1
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Szulik MW, Valdez S, Walsh M, Davis K, Bia R, Horiuchi E, O'Very S, Laxman AK, Sandaklie-Nicolova L, Eberhardt DR, Durrant JR, Sheikh H, Hickenlooper S, Creed M, Brady C, Miller M, Wang L, Garcia-Llana J, Tracy C, Drakos SG, Funai K, Chaudhuri D, Boudina S, Franklin S. SMYD1a protects the heart from ischemic injury by regulating OPA1-mediated cristae remodeling and supercomplex formation. Basic Res Cardiol 2023; 118:20. [PMID: 37212935 PMCID: PMC10203008 DOI: 10.1007/s00395-023-00991-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/26/2022] [Revised: 05/03/2023] [Accepted: 05/10/2023] [Indexed: 05/23/2023]
Abstract
SMYD1, a striated muscle-specific lysine methyltransferase, was originally shown to play a key role in embryonic cardiac development but more recently we demonstrated that loss of Smyd1 in the murine adult heart leads to cardiac hypertrophy and failure. However, the effects of SMYD1 overexpression in the heart and its molecular function in the cardiomyocyte in response to ischemic stress are unknown. In this study, we show that inducible, cardiomyocyte-specific overexpression of SMYD1a in mice protects the heart from ischemic injury as seen by a > 50% reduction in infarct size and decreased myocyte cell death. We also demonstrate that attenuated pathological remodeling is a result of enhanced mitochondrial respiration efficiency, which is driven by increased mitochondrial cristae formation and stabilization of respiratory chain supercomplexes within the cristae. These morphological changes occur concomitant with increased OPA1 expression, a known driver of cristae morphology and supercomplex formation. Together, these analyses identify OPA1 as a novel downstream target of SMYD1a whereby cardiomyocytes upregulate energy efficiency to dynamically adapt to the energy demands of the cell. In addition, these findings highlight a new epigenetic mechanism by which SMYD1a regulates mitochondrial energetics and functions to protect the heart from ischemic injury.
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Affiliation(s)
- Marta W Szulik
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, UT, USA.
| | - Steven Valdez
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, UT, USA
| | - Maureen Walsh
- Diabetes and Metabolism Research Center, University of Utah, Salt Lake City, UT, USA
| | - Kathryn Davis
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, UT, USA
| | - Ryan Bia
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, UT, USA
| | - Emilee Horiuchi
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, UT, USA
| | - Sean O'Very
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, UT, USA
| | - Anil K Laxman
- Metabolic Phenotypic Core Facility, University of Utah, Salt Lake City, UT, USA
| | | | - David R Eberhardt
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, UT, USA
| | | | - Hanin Sheikh
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, UT, USA
| | - Samuel Hickenlooper
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, UT, USA
| | - Magnus Creed
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, UT, USA
| | - Cameron Brady
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, UT, USA
| | - Mickey Miller
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, UT, USA
| | - Li Wang
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, UT, USA
| | - June Garcia-Llana
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, UT, USA
| | - Christopher Tracy
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, UT, USA
| | - Stavros G Drakos
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, UT, USA
- Division of Cardiovascular Medicine, Department of Internal Medicine, School of Medicine, University of Utah, Salt Lake City, UT, USA
| | - Katsuhiko Funai
- Diabetes and Metabolism Research Center, University of Utah, Salt Lake City, UT, USA
| | - Dipayan Chaudhuri
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, UT, USA
- Division of Cardiovascular Medicine, Department of Internal Medicine, School of Medicine, University of Utah, Salt Lake City, UT, USA
- Department of Biochemistry, Department of Biomedical Engineering, University of Utah, Salt Lake City, UT, USA
| | - Sihem Boudina
- Department of Nutrition and Integrative Physiology, Program in Molecular Medicine, University of Utah, Salt Lake City, UT, USA
| | - Sarah Franklin
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, UT, USA.
- Division of Cardiovascular Medicine, Department of Internal Medicine, School of Medicine, University of Utah, Salt Lake City, UT, USA.
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2
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Gogulamudi VR, Islam MT, Durrant JR, Adeyemo AO, Trott DW, Hyuhn MH, Zhu W, Donato AJ, Walker AE, Lesniewski LA. Heterozygosity for ADP-ribosylation factor 6 suppresses the burden and severity of atherosclerosis. PLoS One 2023; 18:e0285253. [PMID: 37163513 PMCID: PMC10171652 DOI: 10.1371/journal.pone.0285253] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2022] [Accepted: 04/18/2023] [Indexed: 05/12/2023] Open
Abstract
Atherosclerosis is the root cause of major cardiovascular diseases (CVD) such as myocardial infarction and stroke. ADP-ribosylation factor 6 (Arf6) is a ubiquitously expressed GTPase known to be involved in inflammation, vascular permeability and is sensitive to changes in shear stress. Here, using atheroprone, ApoE-/- mice, with a single allele deletion of Arf6 (HET) or wildtype Arf6 (WT), we demonstrate that reduction in Arf6 attenuates atherosclerotic plaque burden and severity. We found that plaque burden in the descending aorta was lower in HET compared to WT mice (p˂0.001) after the consumption of an atherogenic Paigen diet for 5 weeks. Likewise, luminal occlusion, necrotic core size, plaque grade, elastic lamina breaks, and matrix deposition were lower in the aortic root atheromas of HET compared to WT mice (all p≤0.05). We also induced advanced human-like complex atherosclerotic plaque in the left carotid artery using partial carotid ligation surgery and found that atheroma area, plaque grade, intimal necrosis, intraplaque hemorrhage, thrombosis, and calcification were lower in HET compared to WT mice (all p≤0.04). Our findings suggest that the atheroprotection afforded by Arf6 heterozygosity may result from reduced immune cell migration (all p≤0.005) as well as endothelial and vascular smooth muscle cell proliferation (both p≤0.001) but independent of changes in circulating lipids (all p≥0.40). These findings demonstrate a critical role for Arf6 in the development and severity of atherosclerosis and suggest that Arf6 inhibition can be explored as a novel therapeutic strategy for the treatment of atherosclerotic CVD.
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Affiliation(s)
- Venkateswara R. Gogulamudi
- Department of Internal Medicine, Division of Geriatrics, The University of Utah, Salt Lake City, Utah, United States of America
| | - Md Torikul Islam
- Department of Nutrition and Integrative Physiology, The University of Utah, Salt Lake City, Utah, United States of America
| | - Jessica R. Durrant
- Dallas Tissue Research, Farmers Branch, Texas, Dallas, United States of America
| | - Adelola O. Adeyemo
- Department of Internal Medicine, Division of Geriatrics, The University of Utah, Salt Lake City, Utah, United States of America
| | - Daniel W. Trott
- Department of Internal Medicine, Division of Geriatrics, The University of Utah, Salt Lake City, Utah, United States of America
- Department of Internal Medicine, Division of Cardiovascular Medicine, The University of Utah, Salt Lake City, Utah, United States of America
| | - Mi Ho Hyuhn
- Department of Internal Medicine, Division of Geriatrics, The University of Utah, Salt Lake City, Utah, United States of America
| | - Weiquan Zhu
- Department of Internal Medicine, Division of Cardiovascular Medicine, The University of Utah, Salt Lake City, Utah, United States of America
- Department of Pathology, The University of Utah, Salt Lake City, Utah, United States of America
- Program of Molecular Medicine, The University of Utah, Salt Lake City, Utah, United States of America
| | - Anthony J. Donato
- Department of Internal Medicine, Division of Geriatrics, The University of Utah, Salt Lake City, Utah, United States of America
- Department of Nutrition and Integrative Physiology, The University of Utah, Salt Lake City, Utah, United States of America
- Geriatric Research Education and Clinical Center, Veteran’s Affairs Medical Center-Salt Lake City, Salt Lake City, Utah, United States of America
- Department of Biochemistry, The University of Utah, Salt Lake City, Utah, United States of America
- Nora Eccles Harrison Cardiovascular Research and Training Institute, The University of Utah, Salt Lake City, Utah, United States of America
| | - Ashley E. Walker
- Department of Internal Medicine, Division of Geriatrics, The University of Utah, Salt Lake City, Utah, United States of America
- Department of Human Physiology, The University of Oregon, Eugene, Oregon, United States of America
| | - Lisa A. Lesniewski
- Department of Internal Medicine, Division of Geriatrics, The University of Utah, Salt Lake City, Utah, United States of America
- Department of Nutrition and Integrative Physiology, The University of Utah, Salt Lake City, Utah, United States of America
- Geriatric Research Education and Clinical Center, Veteran’s Affairs Medical Center-Salt Lake City, Salt Lake City, Utah, United States of America
- Nora Eccles Harrison Cardiovascular Research and Training Institute, The University of Utah, Salt Lake City, Utah, United States of America
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3
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Gogulamudi VR, Durrant JR, Adeyemo AO, Ho HM, Walker AE, Lesniewski LA. Advancing age increases the size and severity of spontaneous atheromas in mouse models of atherosclerosis. GeroScience 2023:10.1007/s11357-023-00776-8. [PMID: 37086367 PMCID: PMC10400524 DOI: 10.1007/s11357-023-00776-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2022] [Accepted: 03/17/2023] [Indexed: 04/23/2023] Open
Abstract
Using multiple mouse models, we explored the impact of aging on the size and severity of atherosclerotic lesions. In young, middle-aged and old apolipoprotein E knockout mice (ApoE-/-) fed an atherogenic diet (AD) for 3-8 weeks, plaque/atheroma formation in the descending aorta and aortic root, and atheroma development in the carotid in response to partial carotid ligation (PCL) were assessed. Total and LDL cholesterol, and triglycerides were higher in old compared to both other age groups, regardless of AD duration. Aortic plaque burden increased with AD duration in all ages. The size and plaque morphology grade of aortic root atheromas was higher with age; however, there was no effect of age on the size or severity of carotid atheromas after PCL. We additionally induced hyperlipidemia in young and old C57BL/6 mice by adeno-associated virus mediated upregulation of LDL receptor regulator, Pcsk9, and 5 weeks of AD. Despite lower cholesterol in old compared to young Pcsk9 mice, there was a greater size and severity of aortic root atheromas in old mice. However, like the ApoE-/- mice, there was no effect of age on size or severity of PCL-induced carotid artery atheromas in Pcsk9 mice. Together, these results suggest that aging increases the size and severity of spontaneous aortic atheromas.
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Affiliation(s)
- Venkateswara R Gogulamudi
- Internal Medicine-Geriatrics, University of Utah, Salt Lake City, UT, USA
- Geriatrics Research Education and Clinical Center, Veteran's Affairs Medical Center-Salt Lake City, Salt Lake City, UT, USA
| | | | - Adelola O Adeyemo
- Internal Medicine-Geriatrics, University of Utah, Salt Lake City, UT, USA
- Geriatrics Research Education and Clinical Center, Veteran's Affairs Medical Center-Salt Lake City, Salt Lake City, UT, USA
| | - Huynh Mi Ho
- Internal Medicine-Geriatrics, University of Utah, Salt Lake City, UT, USA
| | - Ashley E Walker
- Department of Human Physiology, University of Oregon, Eugene, OR, USA
| | - Lisa A Lesniewski
- Internal Medicine-Geriatrics, University of Utah, Salt Lake City, UT, USA.
- Geriatrics Research Education and Clinical Center, Veteran's Affairs Medical Center-Salt Lake City, Salt Lake City, UT, USA.
- Nutrition and Integrative Physiology, University of Utah, Salt Lake City, UT, USA.
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, UT, USA.
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4
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Gogulamudi VR, Machin DR, Henson GD, Lim J, Bramwell RC, Durrant JR, Donato AJ, Lesniewski LA. Sirt1 overexpression attenuates Western-style diet-induced aortic stiffening in mice. Physiol Rep 2022; 10:e15284. [PMID: 35561022 PMCID: PMC9101596 DOI: 10.14814/phy2.15284] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2022] [Accepted: 03/31/2022] [Indexed: 06/15/2023] Open
Abstract
Increased arterial stiffness is a cardiovascular disease risk factor in the setting of advancing age and Western diet (WD) induced obesity. Increases in large artery stiffness, as measured by pulse wave velocity (PWV), occur within 8 weeks of WD feeding in mice. Sirtuin-1 (Sirt1), a NAD-dependent deacetylase, regulates cellular metabolic activity and activation of this protein has been associated with vasoprotection in aged mice. The aim of the study was to elucidate the effect of global Sirt1 overexpression (Sirttg ) on WD-induced arterial stiffening. Sirt1 overexpression did not influence PWV in normal chow (NC) fed mice. However, PWV was higher in wild-type (WT) mice (p < 0.04), but not in Sirttg mice, after 12 weeks of WD and this effect was independent of changes in blood pressure or the passive pressure diameter relation in the carotid artery. Overexpression of Sirt1 was associated with lower collagen and higher elastin mRNA expression in the aorta of WD fed mice (both p < 0.05). Although MMP2 and MMP3 mRNA were both upregulated in WT mice after WD (both p < 0.05), this effect was reversed in Sirttg mice compared to WT mice fed WD (both p < 0.05). Surprisingly, histologically assessed collagen and elastin quality were unchanged in the aortas of WT or Sirttg mice after WD. However, Sirttg mice were protected from WD-induced glucose intolerance, although there was no difference in insulin tolerance between groups. These findings demonstrate a vasoprotective effect of Sirt1 overexpression that limits the increase in arterial stiffness in response to consumption of a WD.
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Affiliation(s)
| | - Daniel R. Machin
- Department of Internal MedicineUniversity of UtahSalt Lake CityUtahUSA
- Department of Nutrition and Integrative PhysiologyFlorida State UniversityTallahasseeFloridaUSA
| | - Grant D. Henson
- Department of Internal MedicineUniversity of UtahSalt Lake CityUtahUSA
| | - Jisok Lim
- Department of Internal MedicineUniversity of UtahSalt Lake CityUtahUSA
| | | | | | - Anthony J. Donato
- Department of Internal MedicineUniversity of UtahSalt Lake CityUtahUSA
- Geriatrics Research Education and Clinical CenterVeteran’s Affairs Medical CenterSalt Lake CityUtahUSA
- Department of Nutrition and Integrative PhysiologyUniversity of UtahSalt Lake CityUtahUSA
| | - Lisa A. Lesniewski
- Department of Internal MedicineUniversity of UtahSalt Lake CityUtahUSA
- Geriatrics Research Education and Clinical CenterVeteran’s Affairs Medical CenterSalt Lake CityUtahUSA
- Department of Nutrition and Integrative PhysiologyUniversity of UtahSalt Lake CityUtahUSA
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5
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Gross SJ, Webb AM, Peterlin AD, Durrant JR, Judson RJ, Raza Q, Kitajewski JK, Kushner EJ. Notch regulates vascular collagen IV basement membrane through modulation of lysyl hydroxylase 3 trafficking. Angiogenesis 2021; 24:789-805. [PMID: 33956260 PMCID: PMC8487879 DOI: 10.1007/s10456-021-09791-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2021] [Accepted: 04/19/2021] [Indexed: 11/26/2022]
Abstract
Collagen type IV (Col IV) is a basement membrane protein associated with early blood vessel morphogenesis and is essential for blood vessel stability. Defects in vascular Col IV deposition are the basis of heritable disorders, such as small vessel disease, marked by cerebral hemorrhage and drastically shorten lifespan. To date, little is known about how endothelial cells regulate the intracellular transport and selective secretion of Col IV in response to angiogenic cues, leaving a void in our understanding of this critical process. Our aim was to identify trafficking pathways that regulate Col IV deposition during angiogenic blood vessel development. We have identified the GTPase Rab10 as a major regulator of Col IV vesicular trafficking during vascular development using both in vitro imaging and biochemistry as well as in vivo models. Knockdown of Rab10 reduced de novo Col IV secretion in vivo and in vitro. Mechanistically, we determined that Rab10 is an indirect mediator of Col IV secretion, partnering with atypical Rab25 to deliver the enzyme lysyl hydroxylase 3 (LH3) to Col IV-containing vesicles staged for secretion. Loss of Rab10 or Rab25 results in depletion of LH3 from Col IV-containing vesicles and rapid lysosomal degradation of Col IV. Furthermore, we demonstrate that Rab10 is Notch responsive, indicating a novel connection between permissive Notch-based vessel maturation programs and vesicle trafficking. Our results illustrate both a new trafficking-based component in the regulated secretion of Col IV and how this vesicle trafficking program interfaces with Notch signaling to fine-tune basement membrane secretion during blood vessel development.
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Affiliation(s)
- Stephen J Gross
- Department of Biological Sciences, University of Denver, Denver, CO, 80210, USA
| | - Amelia M Webb
- Department of Biological Sciences, University of Denver, Denver, CO, 80210, USA
| | - Alek D Peterlin
- Department of Biological Sciences, University of Denver, Denver, CO, 80210, USA
| | | | - Rachel J Judson
- Department of Biological Sciences, University of Denver, Denver, CO, 80210, USA
| | - Qanber Raza
- Department of Physiology and Biophysics, University of Illinois, Chicago, IL, USA
| | - Jan K Kitajewski
- Department of Physiology and Biophysics, University of Illinois, Chicago, IL, USA
| | - Erich J Kushner
- Department of Biological Sciences, University of Denver, Denver, CO, 80210, USA.
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6
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Gross SJ, Webb AM, Peterlin AD, Durrant JR, Judson RJ, Raza Q, Kitajewski JK, Kushner EJ. Correction to: Notch regulates vascular collagen IV basement membrane through modulation of lysyl hydroxylase 3 trafficking. Angiogenesis 2021; 24:807. [PMID: 34101097 PMCID: PMC8487882 DOI: 10.1007/s10456-021-09801-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Stephen J Gross
- Department of Biological Sciences, University of Denver, Denver, CO, 80210, USA
| | - Amelia M Webb
- Department of Biological Sciences, University of Denver, Denver, CO, 80210, USA
| | - Alek D Peterlin
- Department of Biological Sciences, University of Denver, Denver, CO, 80210, USA
| | | | - Rachel J Judson
- Department of Biological Sciences, University of Denver, Denver, CO, 80210, USA
| | - Qanber Raza
- Department of Physiology and Biophysics, University of Illinois, Chicago, IL, USA
| | - Jan K Kitajewski
- Department of Physiology and Biophysics, University of Illinois, Chicago, IL, USA
| | - Erich J Kushner
- Department of Biological Sciences, University of Denver, Denver, CO, 80210, USA.
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7
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Gogulamudi VR, Durrant JR, Donato AJ, Lesniewski LA. Aging exacerbates spontaneous atherosclerosis in apolipoprotein E deficient mice. FASEB J 2020. [DOI: 10.1096/fasebj.2020.34.s1.06010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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8
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Dimitrov SD, Azzouzi M, Wu J, Yao J, Dong Y, Tuladhar PS, Schroeder BC, Bittner ER, McCulloch I, Nelson J, Durrant JR. Spectroscopic Investigation of the Effect of Microstructure and Energetic Offset on the Nature of Interfacial Charge Transfer States in Polymer: Fullerene Blends. J Am Chem Soc 2019; 141:4634-4643. [PMID: 30807130 PMCID: PMC6429453 DOI: 10.1021/jacs.8b11484] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
![]()
Despite
performance improvements of organic photovoltaics, the
mechanism of photoinduced electron–hole separation at organic
donor–acceptor interfaces remains poorly understood. Inconclusive
experimental and theoretical results have produced contradictory models
for electron–hole separation in which the role of interfacial
charge-transfer (CT) states is unclear, with one model identifying
them as limiting separation and another as readily dissociating. Here,
polymer–fullerene blends with contrasting photocurrent properties
and enthalpic offsets driving separation were studied. By modifying
composition, film structures were varied from consisting of molecularly
mixed polymer–fullerene domains to consisting of both molecularly
mixed and fullerene domains. Transient absorption spectroscopy revealed
that CT state dissociation generating separated electron–hole
pairs is only efficient in the high energy offset blend with fullerene
domains. In all other blends (with low offset or predominantly molecularly
mixed domains), nanosecond geminate electron–hole recombination
is observed revealing the importance of spatially localized electron–hole
pairs (bound CT states) in the electron–hole dynamics. A two-dimensional
lattice exciton model was used to simulate the excited state spectrum
of a model system as a function of microstructure and energy offset.
The results could reproduce the main features of experimental electroluminescence
spectra indicating that electron–hole pairs become less bound
and more spatially separated upon increasing energy offset and fullerene
domain density. Differences between electroluminescence and photoluminescence
spectra could be explained by CT photoluminescence being dominated
by more-bound states, reflecting geminate recombination processes,
while CT electroluminescence preferentially probes less-bound CT states
that escape geminate recombination. These results suggest that apparently
contradictory studies on electron–hole separation can be explained
by the presence of both bound and unbound CT states in the same film,
as a result of a range of interface structures.
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Affiliation(s)
- S D Dimitrov
- SPECIFIC, College of Engineering , Swansea University , Bay Campus , Swansea SA1 8EN , United Kingdom
| | | | | | | | | | | | - B C Schroeder
- Department of Chemistry , University College , London WC1H 0AJ , United Kingdom
| | - E R Bittner
- Department of Chemistry , University of Houston , Houston , Texas 77204 , United States
| | - I McCulloch
- Physical Sciences and Engineering Division, KAUST Solar Center (KSC) , King Abdullah University of Science and Technology (KAUST) , Thuwal 23955-6900 , Kingdom of Saudi Arabia
| | | | - J R Durrant
- SPECIFIC, College of Engineering , Swansea University , Bay Campus , Swansea SA1 8EN , United Kingdom
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9
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Walker AE, Breevoort SR, Durrant JR, Liu Y, Machin DR, Dobson PS, Nielson EI, Meza AJ, Islam MT, Donato AJ, Lesniewski LA. The pro-atherogenic response to disturbed blood flow is increased by a western diet, but not by old age. Sci Rep 2019; 9:2925. [PMID: 30814657 PMCID: PMC6393500 DOI: 10.1038/s41598-019-39466-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2018] [Accepted: 01/24/2019] [Indexed: 12/12/2022] Open
Abstract
Atherogenic remodeling often occurs at arterial locations with disturbed blood flow (i.e., low or oscillatory) and both aging and western diet (WD) increase the likelihood for pro-atherogenic remodeling. However, it is unknown if old age and/or a WD modify the pro-atherogenic response to disturbed blood flow. We induced disturbed blood flow by partial carotid ligation (PCL) of the left carotid artery in young and old, normal chow (NC) or WD fed male B6D2F1 mice. Three weeks post-PCL, ligated carotid arteries had greater intima media thickness, neointima formation, and macrophage content compared with un-ligated arteries. WD led to greater remodeling and macrophage content in the ligated artery compared with NC mice, but these outcomes were similar between young and old mice. In contrast, nitrotyrosine content, a marker of oxidative stress, did not differ between WD and NC fed mice, but was greater in old compared with young mice in both ligated and un-ligated carotid arteries. In primary vascular smooth muscle cells, aging reduced proliferation, whereas conditioned media from fatty acid treated endothelial cells increased proliferation. Taken together, these findings suggest that the remodeling and pro-inflammatory response to disturbed blood flow is increased by WD, but is not increased by aging.
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Affiliation(s)
- Ashley E Walker
- Department of Internal Medicine, University of Utah, Salt Lake City, Utah, USA. .,Department of Human Physiology, University of Oregon, Eugene, Oregon, USA.
| | - Sarah R Breevoort
- Department of Internal Medicine, University of Utah, Salt Lake City, Utah, USA
| | | | - Yu Liu
- Department of Internal Medicine, University of Utah, Salt Lake City, Utah, USA
| | - Daniel R Machin
- Department of Internal Medicine, University of Utah, Salt Lake City, Utah, USA.,Geriatrics Research Education and Clinical Center, Veteran's Affairs Medical Center, Salt Lake City, Utah, USA
| | - Parker S Dobson
- Department of Internal Medicine, University of Utah, Salt Lake City, Utah, USA
| | - Elizabeth I Nielson
- Department of Internal Medicine, University of Utah, Salt Lake City, Utah, USA
| | - Antonio J Meza
- Department of Internal Medicine, University of Utah, Salt Lake City, Utah, USA
| | - Md Torikul Islam
- Department of Nutrition and Integrative Physiology, University of Utah, Salt Lake City, Utah, USA
| | - Anthony J Donato
- Department of Internal Medicine, University of Utah, Salt Lake City, Utah, USA.,Geriatrics Research Education and Clinical Center, Veteran's Affairs Medical Center, Salt Lake City, Utah, USA.,Department of Nutrition and Integrative Physiology, University of Utah, Salt Lake City, Utah, USA
| | - Lisa A Lesniewski
- Department of Internal Medicine, University of Utah, Salt Lake City, Utah, USA.,Geriatrics Research Education and Clinical Center, Veteran's Affairs Medical Center, Salt Lake City, Utah, USA.,Department of Nutrition and Integrative Physiology, University of Utah, Salt Lake City, Utah, USA
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10
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Abstract
This paper follows on from the Concluding Remarks presentation of the 3rd Faraday Discussion Meeting on Artificial Photosynthesis, Cambridge, UK, 25-27th March 2019. It aims to discuss the context for the research discussed at this meeting, starting with an overview of the motivation for research on artificial photosynthesis. It then goes onto analysing the composition and trends in the field of artificial photosynthesis, and its scale relative to other related research areas, primarily using the results of searches of publication databases. As such, we hope it provides helpful insights to researchers in the field.
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Affiliation(s)
- C Bozal-Ginesta
- Department of Chemistry, Molecular Sciences Research Hub, Imperial College London, 80 Wood Lane, London W12 0BZ, UK.
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11
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Williams MD, Long CT, Durrant JR, McKeon GP, Shive HR, Griffith EH, Messenger KM, Fish RE. Oral Transmucosal Detomidine Gel in New Zealand White Rabbits ( Oryctolagus cuniculus). J Am Assoc Lab Anim Sci 2017; 56:436-442. [PMID: 28724493 PMCID: PMC5517333] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Received: 01/24/2017] [Revised: 02/27/2017] [Accepted: 05/09/2017] [Indexed: 06/07/2023]
Abstract
Handling and restraining rabbits for routine procedures may be impossible without prior sedation, result in unnecessary stress or injury to the rabbit or handler, and increase experimental variability. Parenteral administration of sedatives can cause stress also, as well as localized pain and tissue damage, especially in fractious animals. Detomidine hydrochloride, an α2-adrenergic receptor agonist, is commercially available in an oral transmucosal (OTM) gel formulation that is FDA-approved for sedation and restraint in horses. This study investigated the efficacy and safety of detomidine gel as an alternative to injectable sedation in rabbits. Eight adult male New Zealand White rabbits each received 0.6, 1.2, or 1.8 mg/kg OTM detomidine gel. Physiologic parameters and sedation scores (SS) were assessed at 10-min intervals from before administration until 100 min afterward. Histopathology of cardiac tissue was scored through 12 d after dosing. Gel administration increased the SS in all rabbits, but none of the animals developed clinically effective sedation (SS of 10 or greater, based on 5 reflex responses on a 3- or 4-point scale). The SS did not differ among dosage groups, and the time-dose interaction was not statistically significant. Heart rate decreased rapidly in all rabbits, with no difference among dosage groups, and there was no effect of time or dosage on peripheral capillary oxygen saturation. Minimal to mild degenerative changes were seen in the myocardium of all treated rabbits, but myocyte necrosis, inflammation, fibrosis, and mural thrombi-reported previously in rabbits that had received parenteral detomidine-did not occur. OTM detomidine gel was safely and easily administered to rabbits, but the duration and level of sedation were unpredictable. The use of OTM detomidine as a sole agent to facilitate handling and restraint of rabbits does not offer advantages over existing parenteral regimens.
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Affiliation(s)
- Morika D Williams
- Departments of Clinical Sciences, North Carolina State University, Raleigh, North Carolina;,
| | - C Tyler Long
- Departments of Clinical Sciences, North Carolina State University, Raleigh, North Carolina
| | - Jessica R Durrant
- Departments of Population Health and Pathobiology, North Carolina State University, Raleigh, North Carolina
| | - Gabriel P McKeon
- Departments of Clinical Sciences, North Carolina State University, Raleigh, North Carolina
| | - Heather R Shive
- Departments of Population Health and Pathobiology, North Carolina State University, Raleigh, North Carolina
| | - Emily H Griffith
- Department of Statistics, College of Sciences, North Carolina State University, Raleigh, North Carolina
| | - Kristen M Messenger
- Departments of Molecular Biomedical Sciences, College of Veterinary Medicine, North Carolina State University, Raleigh, North Carolina
| | - Richard E Fish
- Departments of Clinical Sciences, North Carolina State University, Raleigh, North Carolina
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12
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Meichner K, Kraszeski BH, Durrant JR, Grindem CB, Breuhaus BA, Moore PF, Neel JA, Linder KE, Borst LB, Fogle JE, Tarigo JL. Extreme lymphocytosis with myelomonocytic morphology in a horse with diffuse large B‐cell lymphoma. Vet Clin Pathol 2016; 46:64-71. [DOI: 10.1111/vcp.12435] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Kristina Meichner
- Department of Pathology University of Georgia College of Veterinary Medicine Athens GA USA
| | - Blaire H. Kraszeski
- Department of Clinical Sciences College of Veterinary Medicine North Carolina State University Raleigh NC USA
| | - Jessica R. Durrant
- Department of Population Health and Pathobiology College of Veterinary Medicine North Carolina State University Raleigh NC USA
| | - Carol B. Grindem
- Department of Population Health and Pathobiology College of Veterinary Medicine North Carolina State University Raleigh NC USA
| | - Babetta A. Breuhaus
- Department of Clinical Sciences College of Veterinary Medicine North Carolina State University Raleigh NC USA
| | - Peter F. Moore
- Department of Pathology, Microbiology, and Immunology University of California Davis CA USA
| | - Jennifer A. Neel
- Department of Population Health and Pathobiology College of Veterinary Medicine North Carolina State University Raleigh NC USA
| | - Keith E. Linder
- Department of Population Health and Pathobiology College of Veterinary Medicine North Carolina State University Raleigh NC USA
| | - Luke B. Borst
- Department of Population Health and Pathobiology College of Veterinary Medicine North Carolina State University Raleigh NC USA
| | - Jonathan E. Fogle
- Department of Population Health and Pathobiology College of Veterinary Medicine North Carolina State University Raleigh NC USA
| | - Jaime L. Tarigo
- Department of Pathology University of Georgia College of Veterinary Medicine Athens GA USA
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13
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Baran D, Kirchartz T, Wheeler S, Dimitrov S, Abdelsamie M, Gorman J, Ashraf RS, Holliday S, Wadsworth A, Gasparini N, Kaienburg P, Yan H, Amassian A, Brabec CJ, Durrant JR, McCulloch I. Reduced voltage losses yield 10% efficient fullerene free organic solar cells with >1 V open circuit voltages. Energy Environ Sci 2016; 9:3783-3793. [PMID: 28066506 PMCID: PMC5171224 DOI: 10.1039/c6ee02598f] [Citation(s) in RCA: 152] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/06/2016] [Accepted: 11/08/2016] [Indexed: 05/20/2023]
Abstract
Optimization of the energy levels at the donor-acceptor interface of organic solar cells has driven their efficiencies to above 10%. However, further improvements towards efficiencies comparable with inorganic solar cells remain challenging because of high recombination losses, which empirically limit the open-circuit voltage (Voc) to typically less than 1 V. Here we show that this empirical limit can be overcome using non-fullerene acceptors blended with the low band gap polymer PffBT4T-2DT leading to efficiencies approaching 10% (9.95%). We achieve Voc up to 1.12 V, which corresponds to a loss of only Eg/q - Voc = 0.5 ± 0.01 V between the optical bandgap Eg of the polymer and Voc. This high Voc is shown to be associated with the achievement of remarkably low non-geminate and non-radiative recombination losses in these devices. Suppression of non-radiative recombination implies high external electroluminescence quantum efficiencies which are orders of magnitude higher than those of equivalent devices employing fullerene acceptors. Using the balance between reduced recombination losses and good photocurrent generation efficiencies achieved experimentally as a baseline for simulations of the efficiency potential of organic solar cells, we estimate that efficiencies of up to 20% are achievable if band gaps and fill factors are further optimized.
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Affiliation(s)
- D Baran
- Department of Chemistry and Centre for Plastic Electronics , Imperial College London , London , SW7 2AZ , UK . ; IEK5-Photovoltaics , Forschungszentrum Jülich , 52425 Jülich , Germany .
| | - T Kirchartz
- IEK5-Photovoltaics , Forschungszentrum Jülich , 52425 Jülich , Germany . ; Faculty of Engineering and CENIDE , University of Duisburg-Essen , Carl-Benz-Straße 199 , 47057 Duisburg , Germany
| | - S Wheeler
- Department of Chemistry and Centre for Plastic Electronics , Imperial College London , London , SW7 2AZ , UK .
| | - S Dimitrov
- Department of Chemistry and Centre for Plastic Electronics , Imperial College London , London , SW7 2AZ , UK .
| | - M Abdelsamie
- King Abdullah University of Science and Technology (KAUST) , KSC , Thuwal 23955-6900 , Saudi Arabia
| | - J Gorman
- Department of Chemistry and Centre for Plastic Electronics , Imperial College London , London , SW7 2AZ , UK .
| | - R S Ashraf
- King Abdullah University of Science and Technology (KAUST) , KSC , Thuwal 23955-6900 , Saudi Arabia
| | - S Holliday
- Department of Chemistry and Centre for Plastic Electronics , Imperial College London , London , SW7 2AZ , UK .
| | - A Wadsworth
- Department of Chemistry and Centre for Plastic Electronics , Imperial College London , London , SW7 2AZ , UK .
| | - N Gasparini
- Institute of Materials for Electronics and Energy Technology (I-MEET) , Friedrich-Alexander-University Erlangen-Nuremberg , Erlangen , Germany
| | - P Kaienburg
- IEK5-Photovoltaics , Forschungszentrum Jülich , 52425 Jülich , Germany .
| | - H Yan
- Department of Chemistry and Hong Kong Branch of Chinese National Engineering Research Center for Tissue Restoration & Reconstruction , Hong Kong University of Science and Technology , Clear Water Bay , Kowloon , Hong Kong , China
| | - A Amassian
- King Abdullah University of Science and Technology (KAUST) , KSC , Thuwal 23955-6900 , Saudi Arabia
| | - C J Brabec
- Institute of Materials for Electronics and Energy Technology (I-MEET) , Friedrich-Alexander-University Erlangen-Nuremberg , Erlangen , Germany
| | - J R Durrant
- Department of Chemistry and Centre for Plastic Electronics , Imperial College London , London , SW7 2AZ , UK .
| | - I McCulloch
- Department of Chemistry and Centre for Plastic Electronics , Imperial College London , London , SW7 2AZ , UK . ; King Abdullah University of Science and Technology (KAUST) , KSC , Thuwal 23955-6900 , Saudi Arabia
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14
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Kushner EJ, Ferro LS, Liu JY, Durrant JR, Rogers SL, Dudley AC, Bautch VL. Excess centrosomes disrupt endothelial cell migration via centrosome scattering. ACTA ACUST UNITED AC 2014; 206:257-72. [PMID: 25049273 PMCID: PMC4107782 DOI: 10.1083/jcb.201311013] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Centrosome–microtubule interactions during interphase are important for centrosome clustering and cell polarity. Supernumerary centrosomes contribute to spindle defects and aneuploidy at mitosis, but the effects of excess centrosomes during interphase are poorly understood. In this paper, we show that interphase endothelial cells with even one extra centrosome exhibit a cascade of defects, resulting in disrupted cell migration and abnormal blood vessel sprouting. Endothelial cells with supernumerary centrosomes had increased centrosome scattering and reduced microtubule (MT) nucleation capacity that correlated with decreased Golgi integrity and randomized vesicle trafficking, and ablation of excess centrosomes partially rescued these parameters. Mechanistically, tumor endothelial cells with supernumerary centrosomes had less centrosome-localized γ-tubulin, and Plk1 blockade prevented MT growth, whereas overexpression rescued centrosome γ-tubulin levels and centrosome dynamics. These data support a model whereby centrosome–MT interactions during interphase are important for centrosome clustering and cell polarity and further suggest that disruption of interphase cell behavior by supernumerary centrosomes contributes to pathology independent of mitotic effects.
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Affiliation(s)
- Erich J Kushner
- Department of Biology, McAllister Heart Institute, and Lineberger Comprehensive Cancer Center, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599
| | - Luke S Ferro
- Department of Biology, McAllister Heart Institute, and Lineberger Comprehensive Cancer Center, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599
| | - Jie-Yu Liu
- Department of Biology, McAllister Heart Institute, and Lineberger Comprehensive Cancer Center, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599
| | - Jessica R Durrant
- Department of Biology, McAllister Heart Institute, and Lineberger Comprehensive Cancer Center, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599
| | - Stephen L Rogers
- Department of Biology, McAllister Heart Institute, and Lineberger Comprehensive Cancer Center, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599
| | - Andrew C Dudley
- Department of Biology, McAllister Heart Institute, and Lineberger Comprehensive Cancer Center, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599Department of Biology, McAllister Heart Institute, and Lineberger Comprehensive Cancer Center, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599
| | - Victoria L Bautch
- Department of Biology, McAllister Heart Institute, and Lineberger Comprehensive Cancer Center, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599Department of Biology, McAllister Heart Institute, and Lineberger Comprehensive Cancer Center, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599Department of Biology, McAllister Heart Institute, and Lineberger Comprehensive Cancer Center, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599
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15
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Lesniewski LA, Zigler ML, Durrant JR, Nowlan MJ, Folian BJ, Donato AJ, Seals DR. Aging compounds western diet-associated large artery endothelial dysfunction in mice: prevention by voluntary aerobic exercise. Exp Gerontol 2013; 48:1218-25. [PMID: 23954368 DOI: 10.1016/j.exger.2013.08.001] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2013] [Revised: 07/25/2013] [Accepted: 08/06/2013] [Indexed: 10/26/2022]
Abstract
We tested the hypothesis that aging will exacerbate the negative vascular consequences of exposure to a common physiological stressor, i.e., consumption of a "western" (high fat/high sucrose) diet (WD), by inducing superoxide-associated reductions in nitric oxide (NO) bioavailability, and that this would be prevented by voluntary aerobic exercise. Incremental stiffness and endothelium-dependent dilation (EDD) were measured in the carotid arteries of young (5.4±0.3 mo, N=20) and old (30.4±0.2 mo, N=19) male B6D2F1 mice fed normal chow (NC: 17% fat, 0% sucrose) or a western diet (40% fat, 19% sucrose) and housed in either standard cages or cages equipped with running wheels for 10-14 weeks. Incremental stiffness was higher in old NC (P<0.05) and both young (P<0.01) and old (P<0.01) WD fed mice compared with young NC mice, but WD did not further increase stiffness in the old mice. In cage control mice, maximal EDD was 17% lower in both NC fed old mice and young WD fed mice (P<0.05). Consumption of WD by old mice led to a further 20% reduction in maximal EDD (P<0.05). Incremental stiffness was 28% lower and maximal EDD was 38% greater in old WD fed mice with access to running wheels vs. old WD fed control mice (P<0.05) and not different from young NC fed controls. Wheel running also tended to improve maximal EDD (+9%, P=0.11), but not incremental stiffness in young WD fed mice. Ex vivo treatment with the superoxide scavenger TEMPOL and NO inhibitor l-NAME abolished these respective effects of age, WD and voluntary running on EDD. Ingestion of a WD induces similar degrees of endothelial dysfunction in old and young adult B6D2F1 mice, and these effects are mediated by a superoxide-dependent impairment of NO bioavailability. However, the combination of old age and WD, a common occurrence in our aging society, results in a marked, additive reduction in endothelial function. Importantly, regular voluntary aerobic exercise reduces arterial stiffness and protects against the adverse influence of WD on endothelial function in old animals by preventing superoxide suppression of NO. These findings may have important implications for arterial aging and the prevention of age-associated cardiovascular diseases.
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Affiliation(s)
- Lisa A Lesniewski
- Department of Integrative Physiology, University of Colorado Boulder, 354 UCB, Boulder, CO 80309, United States; School of Medicine, Department of Internal Medicine, Division of Geriatrics, University of Utah, United States; Geriatrics Research Education and Clinical Center, Veterans Administration Medical Center, Salt Lake City Health Care System, 500 Foothill Dr., Salt Lake City, UT 84148, United States.
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16
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Lesniewski LA, Zigler MC, Durrant JR, Donato AJ, Seals DR. Sustained activation of AMPK ameliorates age-associated vascular endothelial dysfunction via a nitric oxide-independent mechanism. Mech Ageing Dev 2012; 133:368-71. [PMID: 22484146 DOI: 10.1016/j.mad.2012.03.011] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2011] [Revised: 02/01/2012] [Accepted: 03/19/2012] [Indexed: 12/21/2022]
Abstract
Exercise restores endothelium-dependent dilation (EDD) in old mice by reducing oxidative stress and increasing nitric oxide (NO) bioavailability. Adenosine monophosphate protein kinase (AMPK) activation mimics some effects of exercise. Old (28-30 months) B6D2F1 mice had reduced arterial AMPK expression and superoxide-mediated suppression of EDD vs. young (3-6 months) controls. Pharmacological activation of AMPK by aminoimidazole carboxamide ribonucleotide (AICAR) for 2 weeks increased arterial AMPK and reversed this superoxide-induced impairment of EDD. The improvement in EDD was independent of NO or prostaglandin signaling, suggesting enhanced endothelium-dependent hyperpolarizing factor-related dilation. AMPK activation may represent a novel therapy for treating age-associated vascular dysfunction.
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Affiliation(s)
- Lisa A Lesniewski
- Department of Integrative Physiology, University of Colorado at Boulder, 354 UCB, Boulder, CO 80309, USA.
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17
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Donato AJ, Magerko KA, Lawson BR, Durrant JR, Lesniewski LA, Seals DR. SIRT-1 and vascular endothelial dysfunction with ageing in mice and humans. J Physiol 2011; 589:4545-54. [PMID: 21746786 DOI: 10.1113/jphysiol.2011.211219] [Citation(s) in RCA: 188] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
We tested the hypothesis that reductions in the cellular deacetylase, sirtuin-1 (SIRT-1), contribute to vascular endothelial dysfunction with ageing via modulation of endothelial nitric oxide synthase (eNOS) acetylation/activation-associated nitric oxide (NO) production. In older (30 months, n = 14) vs. young (5-7 months, n = 16) B6D2F1 mice, aortic protein expression of SIRT-1 and eNOS phosphorylated at serine 1177 were lower (both P < 0.05), and acetylated eNOS was 6-fold higher (P < 0.05), whereas total eNOS did not differ (P = 0.65). Acetylcholine (ACh)-induced peak endothelium-dependent dilatation (EDD) was lower in isolated femoral arteries with ageing (P < 0.001). Incubation with sirtinol, a SIRT-1 inhibitor, reduced EDD in both young and older mice, abolishing age-related differences, whereas co-administration with l-NAME, an eNOS inhibitor, further reduced EDD similarly in both groups. Endothelium-independent dilatation to sodium nitroprusside (EID), was not altered by age or sirtinol treatment. In older (64 ± 1 years, n = 22) vs. young (25 ± 1 years, n = 16) healthy humans, ACh-induced forearm EDD was impaired (P = 0.01) and SIRT-1 protein expression was 37% lower in endothelial cells obtained from the brachial artery (P < 0.05), whereas EID did not differ. In the overall group, EDD was positively related to endothelial cell SIRT-1 protein expression (r = 0.44, P < 0.01). Reductions in SIRT-1 may play an important role in vascular endothelial dysfunction with ageing. SIRT-1 may be a key therapeutic target to treat arterial ageing.
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Affiliation(s)
- Anthony J Donato
- Department of Integrative Physiology, University of Colorado at Boulder, CO, USA.
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18
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Lesniewski LA, Durrant JR, Connell ML, Henson GD, Black AD, Donato AJ, Seals DR. Aerobic exercise reverses arterial inflammation with aging in mice. Am J Physiol Heart Circ Physiol 2011; 301:H1025-32. [PMID: 21622824 DOI: 10.1152/ajpheart.01276.2010] [Citation(s) in RCA: 90] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
We tested the hypothesis that regular aerobic exercise reverses arterial inflammation with aging. When compared with young controls (6.2 ± 0.4 mo; n = 7), old (31.3 ± 0.5 mo; n = 11) male B6D2F1 cage-restricted mice demonstrated increased arterial activation of the proinflammatory transcription factor NF-κB, as indicated by greater aortic phosphorylation of both the inhibitor of NF-κB kinase (IKK) and the p65 subunit of NF-κB (both P < 0.05). Similarly, aortic expression of the proinflammatory cytokines IL-1 and IL-6, IFN-γ, and TNF-α were greater in the old mice (all P < 0.05). Macrophage and T lymphocyte abundance was unchanged with age in the aortic intima and media but was markedly increased in the adventitia and perivascular fat tissue of old mice (all P < 0.05). This proinflammatory arterial phenotype with aging was associated with vascular dysfunction, as reflected by impaired nitric oxide-mediated endothelium-dependent dilation. Voluntary wheel running (10-14 wk) normalized aortic IKK-NF-κB activation, cytokine expression, adventitial and perivascular macrophage infiltration, and vascular function in old mice (32.4 ± 0.3 mo; n = 8) while having no consistent effects in young mice. Short-term voluntary wheel running started late in life reverses arterial inflammation with aging in mice possibly via outside-in actions. These anti-inflammatory effects may play an important role in the amelioration of age-associated vascular dysfunction by regular aerobic exercise.
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Affiliation(s)
- Lisa A Lesniewski
- Department of Integrative Physiology, University of Colorado at Boulder, Boulder, Colorado, USA.
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19
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Lesniewski LA, Durrant JR, Connell ML, Folian BJ, Donato AJ, Seals DR. Salicylate treatment improves age-associated vascular endothelial dysfunction: potential role of nuclear factor kappaB and forkhead Box O phosphorylation. J Gerontol A Biol Sci Med Sci 2011; 66:409-18. [PMID: 21303813 DOI: 10.1093/gerona/glq233] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
We hypothesized that I kappa B kinase (IKK)-mediated nuclear factor kappa B and forkhead BoxO3a phosphorylation will be associated with age-related endothelial dysfunction. Endothelium-dependent dilation and aortic protein expression/phosphorylation were determined in young and old male B6D2F1 mice and old mice treated with the IKK inhibitor, salicylate. IKK activation was greater in old mice and was associated with greater nitrotyrosine and cytokines. Endothelium-dependent dilation, nitric oxide (NO), and endothelial NO synthase phosphorylation were lower in old mice. Endothelium-dependent dilation and NO bioavailability were restored by a superoxide dismutase mimetic. Nuclear factor kappa B and forkhead BoxO3a phosphorylation were greater in old and were associated with increased expression/activity of nicotinamide adenine dinucleotide phosphate oxidase and lower manganese superoxide dismutase expression. Salicylate lowered IKK phosphorylation and reversed age-associated changes in nitrotyrosine, endothelium-dependent dilation, NO bioavailability, endothelial NO synthase, nuclear factor kappa B and forkhead BoxO3a phosphorylation, nicotinamide adenine dinucleotide phosphate oxidase, and manganese superoxide dismutase. Increased activation of IKK with advancing age stimulates nuclear factor kappa B and inactivates forkhead BoxO3a. This altered transcription factor activation contributes to a pro-inflammatory/pro-oxidative arterial phenotype that is characterized by increased cytokines and nicotinamide adenine dinucleotide phosphate oxidase and decreased manganese superoxide dismutase leading to oxidative stress-mediated endothelial dysfunction.
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Affiliation(s)
- Lisa A Lesniewski
- Department of Integrative Physiology, University of Colorado at Boulder, USA.
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20
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Fleenor BS, Marshall KD, Durrant JR, Lesniewski LA, Seals DR. Arterial stiffening with ageing is associated with transforming growth factor-β1-related changes in adventitial collagen: reversal by aerobic exercise. J Physiol 2011; 588:3971-82. [PMID: 20807791 DOI: 10.1113/jphysiol.2010.194753] [Citation(s) in RCA: 151] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
We tested the hypothesis that carotid artery stiffening with ageing is associated with transforming growth factor-β1 (TGF-β1)-related increases in adventitial collagen and reductions in medial elastin, which would be reversed by voluntary aerobic exercise. Ex vivo carotid artery incremental stiffness was greater in old (29–32 months, n = 11) vs. young (4–7 months, n = 8) cage control B6D2F1 mice (8.84 ± 1.80 vs. 4.54 ± 1.18 AU, P < 0.05), and was associated with selective increases in collagen I and III and TGF-β1 protein expression in the adventitia (P < 0.05), related to an increase in smooth muscle α-actin (SMαA) (myofibroblast phenotype) (P < 0.05). In cultured adventitial fibroblasts, TGF-β1 induced increases in superoxide and collagen I protein (P < 0.05), which were inhibited by Tempol, a superoxide dismutase. Medial elastin was reduced with ageing, accompanied by decreases in the pro-synthetic elastin enzyme, lysyl oxidase, and increases in the elastin-degrading enzyme, matrix metalloproteinase 2. Fibronectin was unchanged with ageing, but there was a small increase in calcification (P < 0.05). Increased incremental stiffness in old mice was completely reversed (3.98 ± 0.34 AU, n = 5) by 10–14 weeks of modest voluntary wheel running (1.13 ± 0.29 km day−1), whereas greater voluntary wheel running (10.62 ± 0.49 km day−1) had no effect on young mice. The amelioration of carotid artery stiffness by wheel running in old mice was associated with reductions in collagen I and III and TGF-β1, partial reversal of the myofibroblast phenotype (reduced SMαA) and reduced calcification (all P < 0.05 vs. old controls), whereas elastin and its modulating enzymes were unaffected. Adventitial TGF-β1-related oxidative stress may play a key role in collagen deposition and large elastic artery stiffening with ageing and the efficacious effects of voluntary aerobic exercise.
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Affiliation(s)
- Bradley S Fleenor
- Department of Integrative Physiology, University of Colorado, Boulder, CO 80309, USA.
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21
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Magerko KA, Seals DR, Durrant JR, Lawson BR, Lesniewski LA, Donato AJ. Age‐related impairment in endothelium‐dependent dilation is related to diminished sirT deacetlylase expression and increased eNOS acetylation. FASEB J 2010. [DOI: 10.1096/fasebj.24.1_supplement.1039.2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
| | - Douglas R Seals
- Integrative PhysiologyUniversity of Colorado, BoulderBoulderCO
| | | | - Brooke R Lawson
- Integrative PhysiologyUniversity of Colorado, BoulderBoulderCO
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22
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Lawson BR, Seals DR, Magerko KA, Durrant JR, Zigler ML, Donato AJ, Lesniewski LA. Short‐term AMPK activation improves vascular endothelial function in old mice by a different mechanism than habitual aerobic exercise. FASEB J 2010. [DOI: 10.1096/fasebj.24.1_supplement.619.9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Brooke R Lawson
- Integrative PhysiologyUniversity of Colorado at BoulderBoulderCO
| | - Douglas R Seals
- Integrative PhysiologyUniversity of Colorado at BoulderBoulderCO
| | | | | | - Melanie L Zigler
- Integrative PhysiologyUniversity of Colorado at BoulderBoulderCO
| | - Anthony J Donato
- Integrative PhysiologyUniversity of Colorado at BoulderBoulderCO
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23
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Durrant JR, Seals DR, Connell ML, Russell MJ, Lawson BR, Folian BJ, Donato AJ, Lesniewski LA. Voluntary wheel running restores endothelial function in conduit arteries of old mice: direct evidence for reduced oxidative stress, increased superoxide dismutase activity and down-regulation of NADPH oxidase. J Physiol 2009; 587:3271-85. [PMID: 19417091 DOI: 10.1113/jphysiol.2009.169771] [Citation(s) in RCA: 184] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Habitual aerobic exercise is associated with enhanced endothelium-dependent dilatation (EDD) in older humans, possibly by increasing nitric oxide bioavailability and reducing oxidative stress. However, the mechanisms involved are incompletely understood. EDD was measured in young (6-8 months) and old (29-32 months) cage control and voluntary wheel running (VR) B6D2F1 mice. Age-related reductions in maximal carotid artery EDD to acetylcholine (74 vs. 96%, P < 0.01) and the nitric oxide (NO) component of EDD (maximum dilatation with ACh and l-NAME minus that with ACh alone was -28% vs. -55%, P < 0.01) were restored in old VR (EDD: 96%, NO: -46%). Nitrotyrosine, a marker of oxidative stress, was increased in aorta with age, but was markedly lower in old VR (P < 0.05). Aortic superoxide dismutase (SOD) activity was greater (P < 0.01), whereas NADPH oxidase protein expression (P < 0.01) and activity (P = 0.05) were lower in old VR vs. old cage control. Increasing SOD (with 4-hydroxy-2,2,6,6-tetramethylpiperidine 1-oxyl) and inhibition of NADPH oxidase (with apocynin) improved EDD and its NO component in old cage control, but not old VR mice. VR increased endothelial NO synthase (eNOS) protein expression (P < 0.05) and activation (Ser1177 phosphorylation) (P < 0.05) in old mice. VR did not affect EDD in young mice. Our results show that voluntary aerobic exercise restores the age-associated loss of EDD by suppression of oxidative stress via stimulation of SOD antioxidant activity and inhibition of NADPH oxidase superoxide production. Increased eNOS protein and activation also may contribute to exercise-mediated preservation of NO bioavailability and EDD with ageing.
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Affiliation(s)
- Jessica R Durrant
- Department of Integrative Physiology, University of Colorado at Boulder, 80309, USA
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24
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Connell ML, Durrant JR, Russell MJ, Donato AJ, Seals DR, Lesniewski LA. Voluntary wheel running abolishes vascular inflammation and restores endothelial function in old mice. FASEB J 2009. [DOI: 10.1096/fasebj.23.1_supplement.777.6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
| | | | - Molly J Russell
- Integrative PhysiologyUniversity of Colorado, BoulderBoulderCO
| | | | - Douglas R Seals
- Integrative PhysiologyUniversity of Colorado, BoulderBoulderCO
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Russell MJ, Folian BJ, Durrant JR, Connell ML, Seals DR, Lesniewski LA. Aging increases susceptibility to western diet‐induced glucose intolerance and insulin resistance in mice. FASEB J 2009. [DOI: 10.1096/fasebj.23.1_supplement.990.18] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Molly J Russell
- Integrative PhysiologyUniversity of Colorado‐BoulderBoulderCO
| | - Brian J Folian
- Integrative PhysiologyUniversity of Colorado‐BoulderBoulderCO
| | | | | | - Douglas R Seals
- Integrative PhysiologyUniversity of Colorado‐BoulderBoulderCO
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Fleenor BS, Lesniewski LA, Durrant JR, Connell ML, Donato AJ, Seals DR. Voluntary aerobic exercise abolishes age‐associated arterial stiffening in mice: relation to collagen subtype expression in the medial and adventitial layers. FASEB J 2009. [DOI: 10.1096/fasebj.23.1_supplement.774.13] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Bradley S Fleenor
- Department of Integrative PhysiologyUniversity of Colorado at BoulderBoulderCO
| | - Lisa A Lesniewski
- Department of Integrative PhysiologyUniversity of Colorado at BoulderBoulderCO
| | - Jessica R Durrant
- Department of Integrative PhysiologyUniversity of Colorado at BoulderBoulderCO
| | - Melanie L Connell
- Department of Integrative PhysiologyUniversity of Colorado at BoulderBoulderCO
| | - Anthony J Donato
- Department of Integrative PhysiologyUniversity of Colorado at BoulderBoulderCO
| | - Douglas R Seals
- Department of Integrative PhysiologyUniversity of Colorado at BoulderBoulderCO
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27
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Durrant JR, Folian BJ, Connell ML, Russell MJ, Seals DR, Lesniewski LA. Chronic aerobic exercise opposes age‐ and high fat diet‐associated vascular endothelial dysfunction: relation to IKKβ and AMPK. FASEB J 2009. [DOI: 10.1096/fasebj.23.1_supplement.777.7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
| | - Brian J Folian
- Integrative PhysiologyUniversity of Colorado at BoulderBoulderCO
| | | | - Molly J Russell
- Integrative PhysiologyUniversity of Colorado at BoulderBoulderCO
| | - Douglas R Seals
- Integrative PhysiologyUniversity of Colorado at BoulderBoulderCO
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Lesniewski LA, Connell ML, Durrant JR, Folian BJ, Anderson MC, Donato AJ, Seals DR. B6D2F1 Mice are a suitable model of oxidative stress-mediated impaired endothelium-dependent dilation with aging. J Gerontol A Biol Sci Med Sci 2009; 64:9-20. [PMID: 19211548 DOI: 10.1093/gerona/gln049] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
To determine if B6D2F1 mice represent a suitable model of oxidative stress-mediated impaired endothelium-dependent dilation (EDD) with aging, mice were studied at 6.9 +/- 0.3 and 31.9 +/- 0.6 months. EDD to acetylcholine (ACh) was 26% (p < .001) and 12% (p < .001) lower, respectively, in isolated carotid (n = 10-11) and femoral (n = 10) arteries from older mice, and reductions in arterial pressure to systemic ACh infusion were smaller in older mice (n = 6-10; p < .01). Nitrotyrosine was marked in aorta of older mice (p < .05, n = 4). Superoxide production in carotid arteries was greater (p < .05), and TEMPOL restored dilation in carotid arteries and systemically in older mice. N(G)-nitro-l-arginine methyl ester (l-NAME) reduced carotid artery dilation in young more than older mice, whereas TEMPOL restored the effects of l-NAME in older mice. Carotid artery stiffness was increased in older compared with young mice (p = .04). Our results provide the first comprehensive evidence that B6D2F1 mice are a useful model for investigating mechanisms of reduced nitric oxide-dependent, oxidative stress-associated EDD and increased arterial stiffness with aging.
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Affiliation(s)
- Lisa A Lesniewski
- Department of Integrative Physiology, University of Colorado at Boulder, 80309, USA.
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Folian BJ, Durrant JR, Connell ML, Russell MJ, Seals DR, Lesniewski LA. Aging is Associated with Increased Susceptibility to Western Diet‐Induced Glucose Intolerance and Endothelial Dysfunction in Mice. FASEB J 2008. [DOI: 10.1096/fasebj.22.1_supplement.1226.7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
| | | | | | - Molly J Russell
- Integrative PhysiologyUniversity of Colorado at BoulderBoulderCO
| | - Douglas R Seals
- Integrative PhysiologyUniversity of Colorado at BoulderBoulderCO
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30
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Connell ML, Durrant JR, Folian BJ, Russell MJ, Seals DR, Lesniewski LA. Anti‐inflammatory treatment restores endothelium‐dependent dilation in older mice by increasing nitric oxide bioavailability. FASEB J 2008. [DOI: 10.1096/fasebj.22.1_supplement.967.5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Abstract
The recombination kinetics of photogenerated charge carriers in perylene-3, 4, 9, 10-tetracarboxylic dianhydride (PTCDA) and copper phthalocyanine (CuPc) thin films grown by organic molecular beam deposition have been studied using transient absorption spectroscopy. Optical excitation is observed to generate long-lived polaron states, which exhibit power law recombination dynamics on time scales from microseconds to milliseconds. Studies as a function of excitation density and temperature, and comparison between heterostructures and PTCDA single layers, all indicate that this power law behavior results from trapping of PTCDA- polarons in localized states, with an estimated trap state density of approximately 6 x 10(17) polarons cm(-3). This recombination behavior is found to be remarkably similar to that previously observed for polymer/fullerene blends, suggesting that it may be generic to a range of semiconducting materials.
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Affiliation(s)
- S Heutz
- Centre for Electronic Materials and Devices, Department of Chemistry, Imperial College London, London SW7 2AZ, United Kingdom.
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Klein C, Nazeeruddin MK, Liska P, Di Censo D, Hirata N, Palomares E, Durrant JR, Grätzel M. Engineering of a Novel Ruthenium Sensitizer and Its Application in Dye-Sensitized Solar Cells for Conversion of Sunlight into Electricity. Inorg Chem 2004; 44:178-80. [PMID: 15651860 DOI: 10.1021/ic048810p] [Citation(s) in RCA: 176] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A novel ligand 4,4'-bis(carboxyvinyl)-2,2'-bipyridine (L) and its ruthenium(II) complex [Ru(II)L(2)(NCS)(2)] (K8) were synthesized and characterized by analytical, spectroscopic, and electrochemical techniques. The performance of the K8 complex as a charge transfer photosensitizer in nanocrystalline TiO(2) based solar cells was studied. When the K8 complex anchored onto a nanocrystalline TiO(2) film, we achieved very efficient sensitization yielding 77 +/-5% incident photon-to-current efficiencies (IPCE) in the visible region using an electrolyte consisting of 0.6 M methyl-N-butyl imidiazolium iodide, 0.05 M iodine, 0.05 M LiI, and 0.5 M 4-tert-butylpyridine in a 50/50 (v/v) mixture of valeronitrile and acetonitrile. Under standard AM 1.5 sunlight, the complex K8 gave a short circuit photocurrent density of 18 +/- 0.5 mA/cm(2), and the open circuit voltage was 640 +/- 50 mV with fill factor of 0.75 +/- 0.05, corresponding to an overall conversion efficiency of 8.64 +/- 0.5%.
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Affiliation(s)
- C Klein
- Laboratory for Photonics and Interfaces, Institute of Chemical Sciences and Engineering, School of Basic Sciences, Swiss Federal Institute of Technology, CH-1015 Lausanne, Switzerland
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Barter LM, Bianchietti M, Jeans C, Schilstra MJ, Hankamer B, Diner BA, Barber J, Durrant JR, Klug DR. Relationship between excitation energy transfer, trapping, and antenna size in photosystem II. Biochemistry 2001; 40:4026-34. [PMID: 11300783 DOI: 10.1021/bi001724q] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We present a systematic study of the effect of antenna size on energy transfer and trapping in photosystem II. Time-resolved fluorescence experiments have been used to probe a range of particles isolated from both higher plants and the cyanobacterium Synechocystis 6803. The isolated reaction center dynamics are represented by a quasi-phenomenological model that fits the extensive time-resolved data from photosystem II reaction centers and reaction center mutants. This representation of the photosystem II "trapping engine" is found to correctly predict the extent of, and time scale for, charge separation in a range of photosystem II particles of varying antenna size (8-250 chlorins). This work shows that the presence of the shallow trap and slow charge separation kinetics, observed in isolated D1/D2/cyt b559 reaction centers, are indeed retained in larger particles and that these properties are reflected in the trapping dynamics of all larger photosystem II preparations. A shallow equilibrium between the antennae and reaction center in photosystem II will certainly facilitate regulation via nonphotochemical quenching, and one possible interpretation of these findings is therefore that photosystem II is optimized for regulation rather than for efficiency.
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Affiliation(s)
- L M Barter
- Departments of Biochemistry and Chemistry, Imperial College, London SW7 2AY, UK
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34
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Topoglidis E, Lutz T, Willis RL, Barnett CJ, Cass AE, Durrant JR. Protein adsorption on nanoporous TiO2 films: a novel approach to studying photoinduced protein/electrode transfer reactions. Faraday Discuss 2001:35-46; discussion 67-75. [PMID: 11197489 DOI: 10.1039/b003313h] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We have investigated the use of nanoporous TiO2 films as substrates for protein immobilisation. Such films are of interest due to their high surface area, optical transparency, electrochemical activity and ease of fabrication. These films moreover allow detailed spectroscopic study of protein/electrode electron transfer processes. We find that protein immobilisation on such films may be readily achieved from aqueous solutions at 4 degrees C with a high binding stability and no detectable protein denaturation. The nanoporous structure of the film greatly enhances the active surface area available for protein binding (by a factor of up to 850 for an 8 microns thick film). We demonstrate that the redox state of proteins such as immobilised cytochrome-c (Cyt-c) and haemoglobin (Hb) may be modulated by the application of an electrical bias potential to the TiO2 film, without the addition of electron transfer mediators. The binding of Cyt-c on the TiO2 films is investigated as a function of film thickness, protein concentration, protein surface charge and ionic strength. We demonstrate the potential use of immobilised Hb on such TiO2 films for the detection of dissolved CO in aqueous solutions. We further show that protein/electrode electron transfer may be initiated by UV bandgap excitation of the TiO2 electrode. Both photooxidation and photoreduction of the immobilised proteins can be achieved. By employing pulsed UV laser excitation, the interfacial electron transfer kinetics can be monitored by transient optical spectroscopy, providing a novel probe of protein/electrode electron transfer kinetics. We conclude that nanoporous TiO2 films may be useful both for basic studies of protein/electrode interactions and for the development of novel bioanalytical devices such as biosensors.
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Affiliation(s)
- E Topoglidis
- Departments of Biochemistry and Chemistry, Imperial College of Science, Technology and Medicine, South Kensington, London, UK SW7 2AY
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35
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Merry SA, Nixon PJ, Barter LM, Schilstra M, Porter G, Barber J, Durrant JR, Klug DR. Modulation of quantum yield of primary radical pair formation in photosystem II by site-directed mutagenesis affecting radical cations and anions. Biochemistry 1998; 37:17439-47. [PMID: 9860859 DOI: 10.1021/bi980502d] [Citation(s) in RCA: 72] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Pigment-protein interactions play a significant role in determining the properties of photosynthetic complexes. Site-directed mutants of Synechocystis PCC 6803 have been prepared which modify the redox potential of the primary radical pair anion and cation. In one set of mutants, the environment of P680, the primary electron donor of Photosystem II, has been modified by altering the residue at D1-His198. It has been proposed that this residue is an axial ligand to the magnesium cation. In the other set, the D1-Gln130 residue, which is thought to interact with the C9-keto group of the pheophytin electron acceptor, has been changed. The effect of these mutations is to alter the free energy of the primary radical pair state, which causes a change in the equilibrium between excited singlet states and radical pair states. We show that the free energy of the primary radical pair can be increased or decreased by modifications at either the D1-His198 or the D1-Gln130 sites. This is demonstrated by using three independent measures of quantum yield and equilibrium constant, which exhibit a quantitative correlation. These data also indicate the presence of a fast nonradiative decay pathway that competes with primary charge separation. These results emphasize the sensitivity of the primary processes of PS II to small changes in the free energy of the primary radical pair.
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Affiliation(s)
- S A Merry
- Molecular Dynamics and Photosynthesis Research Groups, Centre for Photomolecular Sciences, Department of Biochemistry, Imperial College, London, U.K
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36
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Durrant JR, Tachibana Y, Moser JE, Grätzel M, Klug DR. Interfacial electron transfer in dye sensitised nanocrystalline TiO2 films. J CHEM SCI 1997. [DOI: 10.1007/bf02869203] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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37
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Giorgi LB, Nixon PJ, Merry SA, Joseph DM, Durrant JR, De Las Rivas J, Barber J, Porter G, Klug DR. Comparison of primary charge separation in the photosystem II reaction center complex isolated from wild-type and D1-130 mutants of the cyanobacterium Synechocystis PCC 6803. J Biol Chem 1996; 271:2093-101. [PMID: 8567665 DOI: 10.1074/jbc.271.4.2093] [Citation(s) in RCA: 66] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
We compare primary charge separation in a photosystem II reaction center preparation isolated from a wild-type (WT) control strain of the cyanobacterium Synechocystis sp. PCC 6803 and from two site-directed mutants of Synechocystis in which residue 130 of the D1 polypeptide has been changed from a glutamine to either a glutamate (mutant D1-Gln130Glu), as in higher plant sequences, or a leucine residue (mutant D1-Gln130Leu). The D1-130 residue is thought to be close to the pheophytin electron acceptor. We show that, when P680 is photoselectively excited, the primary radical pair state P680+Ph- is formed with a time constant of 20-30 ps in the WT and both mutants; this time constant is very similar to that observed in Pisum sativum (a higher plant). We also show that a change in the residue at position D1-130 causes a shift in the peak of the pheophytin Qx-band. Nanosecond and picosecond transient absorption measurements indicate that the quantum yield of radical pair formation (phi RP), associated with the 20-30-ps component, is affected by the identify of the D1-130 residue. We find that, for the isolated photosystem II reaction center particle, phi RP higher plant > phi RP D1-Gln130Glu mutant > phi RP WT > phi RP D1-Gln130Leu mutant. Furthermore, the spectroscopic and quantum yield differences we observe between the WT Synechocystis and higher plant photosystem II, seem to be reversed by mutating the D1-130 ligand so that it is the same as in higher plants. This result is consistent with the previously observed natural regulation of quantum yield in Synechococcus PS II by particular changes in the D1 polypeptide amino acid sequence (Clark, A.K., Hurry, V. M., Gustafsson, P. and Oquist, G. (1993) Proc. Natl. Acad. Sci. U.S.A. 90, 11985-11989).
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Affiliation(s)
- L B Giorgi
- Department of Biochemistry, Imperial College, London, United Kingdom
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38
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Durrant JR, Klug DR, Kwa SL, van Grondelle R, Porter G, Dekker JP. A multimer model for P680, the primary electron donor of photosystem II. Proc Natl Acad Sci U S A 1995; 92:4798-802. [PMID: 11607546 PMCID: PMC41794 DOI: 10.1073/pnas.92.11.4798] [Citation(s) in RCA: 167] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
We consider a model of the photosystem II (PS II) reaction center in which its spectral properties result from weak (approximately 100 cm-1) excitonic interactions between the majority of reaction center chlorins. Such a model is consistent with a structure similar to that of the reaction center of purple bacteria but with a reduced coupling of the chlorophyll special pair. We find that this model is consistent with many experimental studies of PS II. The similarity in magnitude of the exciton coupling and energetic disorder in PS II results in the exciton states being structurally highly heterogeneous. This model suggests that P680, the primary electron donor of PS II, should not be considered a dimer but a multimer of several weakly coupled pigments, including the pheophytin electron acceptor. We thus conclude that even if the reaction center of PS II is structurally similar to that of purple bacteria, its spectroscopy and primary photochemistry may be very different.
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Affiliation(s)
- J R Durrant
- Centre for Photomolecular Sciences, Department of Biochemistry, Imperial College, London, United Kingdom
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Vacha F, Joseph DM, Durrant JR, Telfer A, Klug DR, Barber J. Photochemistry and spectroscopy of a five-chlorophyll reaction center of photosystem II isolated by using a Cu affinity column. Proc Natl Acad Sci U S A 1995; 92:2929-33. [PMID: 11607522 PMCID: PMC42332 DOI: 10.1073/pnas.92.7.2929] [Citation(s) in RCA: 67] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
A reaction center of photosystem II was isolated from Pisum sativum by using immobilized metal affinity chromatography. This reaction center is photochemically active and has a room temperature Qgamma chlorophyll (Chl) absorption band peaking at 677.5 nm. From HPLC analysis, the pigment stoichiometry was suggested to be 5 Chls per 1 beta-carotene per 2 pheophytins. Low-temperature absorption measurements at 77 K were consistent with the removal of one of the Chls associated with the usual form of the reaction center isolated by using ion-exchange chromatography. Transient absorption spectroscopy on the picosecond time scale indicated that the Chl removed belongs to a pool of Chl absorbing at approximately 670 nm (C670II) that transfers energy relatively slowly to the primary donor P680 in support of our recently proposed model. The results also support the previous conclusion that radical pair formation is largely associated with a 21-ps time constant when P680 is directly excited and that the identity of C670II is likely to be peripherally bound Chls possibly ligated to conserved His residues at positions 118 on the D1 and D2 proteins.
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Affiliation(s)
- F Vacha
- Photosynthesis Research and Molecular Dynamics Groups, Centre for Photomolecular Sciences, Wolfson Laboratories, Department of Biochemistry, Imperial College of Science, Technology and Medicine, London, United Kingdom
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40
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Rech T, Durrant JR, Joseph DM, Barber J, Porter G, Klug DR. Does slow energy transfer limit the observed time constant for radical pair formation in photosystem II reaction centers? Biochemistry 1994; 33:14768-74. [PMID: 7993905 DOI: 10.1021/bi00253a015] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
We have used spectrally photoselective femtosecond transient absorption spectroscopy on photosystem II reaction centers to show that there are at least two pools of chlorin molecules/states which can transfer excitation energy to P680, the primary electron donor in photosystem II. It has previously been shown that one chlorin pool equilibrates with P680 in 100 fs [Durrant et al. (1992) Proc. Natl. Acad. Sci. U.S.A. 89, 11632-11636], and we report here the observation of energy transfer from a second more weakly coupled chlorin pool. The effect of the weakly coupled pool is to increase the apparent time constant for radical pair formation from 21 ps when P680 is selectively excited to 27 ps when the accessory chlorins are excited. We conclude that it is possible to observe both radical pair formation somewhat slowed by an energy transfer step and radical pair formation not limited by this slow energy transfer, depending upon which chromophores are initially excited. These observations provide evidence that when using photoselective excitation of P680, the observed 21 ps time constant for radical pair formation is not limited by a slow energy transfer step.
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Affiliation(s)
- T Rech
- Department of Biochemistry, Imperial College, U.K
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41
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Durrant JR, Hastings G, Joseph DM, Barber J, Porter G, Klug DR. Rate of oxidation of P680 in isolated photosystem 2 reaction centers monitored by loss of chlorophyll stimulated emission. Biochemistry 1993; 32:8259-67. [PMID: 8347624 DOI: 10.1021/bi00083a029] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
We have continued our studies of the primary photochemistry of isolated photosystem 2 reaction centers using femtosecond transient absorption spectroscopy. Experiments were performed over a wide range of excitation and probe wavelengths, using several data collection time scales. This has enabled us to resolve five different lifetimes ranging between 100 fs and 200 ps plus a nanosecond component. We demonstrate here and elsewhere [e.g., Durrant, J.R., Hastings, G., Joseph, D. M., Barber, J., Porter, G., & Klug, D. R. (1992) Proc. Natl. Acad. Sci. U.S.A. 89, 11632-11636] that the kinetic spectra associated with all but two of these lifetimes are clearly distinguishable. We have previously reported that a 21-ps lifetime is associated with pheophytin reduction [Hastings, G., Durrant, J. R., Hong, Q., Barber, J., Porter, G., & Klug, D. R. (1992) Biochemistry 31, 7638-7647]. In this paper, we show that it is possible to spectrally and temporally resolve stimulated emission from PS2 reaction centers with great accuracy and that this stimulated emission is largely unaffected by those kinetic components which are faster than 21 ps. The observation of a distinct stimulated emission band allows us to distinguish charge-separated states from chlorin singlet states. In this way, we are able to show that the proportion of charge-separated states prior to the 21-ps component is between 0% and 25%. We also show that the shape of the spectrum which we obtain for the state P680+Ph- is essentially invariant between 100 ps and 9 ns, and is the same as that previously reported for P680+Ph- by other researchers.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- J R Durrant
- Department of Biology, Imperial College, London, U.K
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42
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Durrant JR, Hastings G, Joseph DM, Barber J, Porter G, Klug DR. Subpicosecond equilibration of excitation energy in isolated photosystem II reaction centers. Proc Natl Acad Sci U S A 1992; 89:11632-6. [PMID: 1454856 PMCID: PMC50607 DOI: 10.1073/pnas.89.23.11632] [Citation(s) in RCA: 87] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Photosystem II reaction centers have been studied by femtosecond transient absorption spectroscopy. We demonstrate that it is possible to achieve good photoselectivity between the primary electron donor P680 and the majority of the accessory chlorins. Energy transfer can be observed in both directions between P680 and these accessory chlorins depending on which is initially excited. After excitation of either P680 or the other chlorins, the excitation energy is observed to equilibrate between the majority of these pigments at a rate of 100 +/- 50 fs-1. This energy-transfer equilibration takes place before any electron-transfer reactions and must therefore be taken into account in studies of primary electron-transfer reactions in photosystem II. We also show further evidence that the initially excited P680 excited singlet state is delocalized over at least two chlorins and that this delocalization lasts for at least 200 fs.
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Affiliation(s)
- J R Durrant
- Department of Biology, Imperial College, London, United Kingdom
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De Las Rivas J, Crystall B, Booth PJ, Durrant JR, Ozer S, Porter G, Klug DR, Barber J. Long-lived primary radical pair state detected by time-resolved fluorescence and absorption spectroscopy in an isolated Photosystem two core. Photosynth Res 1992; 34:419-431. [PMID: 24408837 DOI: 10.1007/bf00029816] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/26/1992] [Accepted: 06/08/1992] [Indexed: 06/03/2023]
Abstract
A Photosystem two (PS II) core preparation containing the chlorophyll a binding proteins CP 47, CP 43, D1 and D2, and the non-chlorophyll binding cytochrome-b559 and 33 kDA polypeptides, has been isolated from PS II-enriched membranes of peas using the non-ionic detergent heptylthioglucopyranoside and elevated ionic strengths. The primary radical pair state, P680(+)Pheo(-), was studied by time-resolved absorption and fluorescence spectroscopy, under conditions where quinone reduction and water-splitting activities were inhibited. Charge recombination of the primary radical pair in PS II cores was found to have lifetimes of 17.5 ns measured by fluorescence and 21 ns measured by transient decay kinetics under anaerobic conditions. Transient absorption spectroscopy demonstrated that the activity of the particles, based on primary radical pair formation, was in excess of 70% (depending on the choice of kinetic model), while time-resolved fluorescence spectroscopy indicated that the particles were 91% active. These estimates of activity were further supported by steady-state measurements which quantified the amount of photoreducible pheophytin. It is concluded that the PS II core preparation we have isolated is ideal for studying primary radical pair formation and recombination as demonstrated by the correlation of our absorption and fluorescence transient data, which is the first of its kind to be reported in the literature for isolated PS II core complexes from higher plants.
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Hastings G, Durrant JR, Barber J, Porter G, Klug DR. Observation of pheophytin reduction in photosystem two reaction centers using femtosecond transient absorption spectroscopy. Biochemistry 1992; 31:7638-47. [PMID: 1510949 DOI: 10.1021/bi00148a027] [Citation(s) in RCA: 77] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Photosystem two reaction centers have been studied using a sensitive femtosecond transient absorption spectrometer. Measurements were performed at 295 K using different excitation wavelengths and excitation intensities which are shown to avoid multiphoton absorption by the reaction centers. Analyses of results collected over a range of time scales and probe wavelengths allowed the resolution of two exponential components in addition to those previously reported [Durrant, J. R., Hastings, G., Hong, Q., Barber, J., Porter, G., & Klug, D. R. (1992) Chem. Phys. Lett. 188, 54-60], plus the long-lived radical pair itself. A 21-ps component was observed. The process(es) responsible for this component was (were) found to produce bleaching of a pheophytin ground-state absorption band at 545 nm and the simultaneous appearance of a pheophytin anion absorption band at 460 nm resulting in a transient spectrum which was that of the radical pair P680+Ph-. This component is assigned to the production of reduced pheophytin. A lower limit of 60% of the final pheophytin reduction was found to occur at this rate. Despite subtle differences in transient spectra, the lifetime and yield of this pheophytin reduction are essentially independent of excitation wavelength within the signal to noise limitations of these experiments. A long-lived species was also observed. This species is produced by those processes which result in the 21-ps component, and it has a spectrum which is found to be independent of excitation wavelength. This spectrum is characteristic of the primary radical pair state P680+Ph-. In addition, a 200-ps component was found which is tentatively assigned to a slow energy-transfer/trapping process. This component was absent if P680 was excited directly and is therefore not integral to primary radical pair formation. Overall, it is concluded that the rate of pheophytin reduction is limited to (21 ps)-1, even when P680 is directly excited.
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Affiliation(s)
- G Hastings
- Department of Biology, Imperial College, London, United Kingdom
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