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Polo CC, Fonseca-Alaniz MH, Chen JH, Ekman A, McDermott G, Meneau F, Krieger JE, Miyakawa AA. Three-dimensional imaging of mitochondrial cristae complexity using cryo-soft X-ray tomography. Sci Rep 2020; 10:21045. [PMID: 33273629 PMCID: PMC7713364 DOI: 10.1038/s41598-020-78150-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [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: 06/24/2020] [Accepted: 11/17/2020] [Indexed: 12/12/2022] Open
Abstract
Mitochondria are dynamic organelles that change morphology to adapt to cellular energetic demands under both physiological and stress conditions. Cardiomyopathies and neuronal disorders are associated with structure-related dysfunction in mitochondria, but three-dimensional characterizations of the organelles are still lacking. In this study, we combined high-resolution imaging and 3D electron density information provided by cryo-soft X-ray tomography to characterize mitochondria cristae morphology isolated from murine. Using the linear attenuation coefficient, the mitochondria were identified (0.247 ± 0.04 µm-1) presenting average dimensions of 0.90 ± 0.20 µm in length and 0.63 ± 0.12 µm in width. The internal mitochondria structure was successfully identified by reaching up the limit of spatial resolution of 35 nm. The internal mitochondrial membranes invagination (cristae) complexity was calculated by the mitochondrial complexity index (MCI) providing quantitative and morphological information of mitochondria larger than 0.90 mm in length. The segmentation to visualize the cristae invaginations into the mitochondrial matrix was possible in mitochondria with MCI ≥ 7. Altogether, we demonstrated that the MCI is a valuable quantitative morphological parameter to evaluate cristae modelling and can be applied to compare healthy and disease state associated to mitochondria morphology.
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Affiliation(s)
- Carla C Polo
- Brazilian Synchrotron Light Laboratory (LNLS), Brazilian Centre for Research in Energy and Materials (CNPEM), Campinas, SP, 13083-970, Brazil.
| | - Miriam H Fonseca-Alaniz
- Laboratory of Genetics and Molecular Cardiology, Heart Institute (InCor), University of São Paulo Medical School, São Paulo, SP, Brazil
| | - Jian-Hua Chen
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
- Department of Anatomy, University of California San Francisco, San Francisco, CA, 94158, USA
| | - Axel Ekman
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Gerry McDermott
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Florian Meneau
- Brazilian Synchrotron Light Laboratory (LNLS), Brazilian Centre for Research in Energy and Materials (CNPEM), Campinas, SP, 13083-970, Brazil
| | - José E Krieger
- Laboratory of Genetics and Molecular Cardiology, Heart Institute (InCor), University of São Paulo Medical School, São Paulo, SP, Brazil
| | - Ayumi A Miyakawa
- Laboratory of Genetics and Molecular Cardiology, Heart Institute (InCor), University of São Paulo Medical School, São Paulo, SP, Brazil.
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Polo CC, Pereira L, Mazzafera P, Flores-Borges DNA, Mayer JLS, Guizar-Sicairos M, Holler M, Barsi-Andreeta M, Westfahl H, Meneau F. Correlations between lignin content and structural robustness in plants revealed by X-ray ptychography. Sci Rep 2020; 10:6023. [PMID: 32265529 PMCID: PMC7138792 DOI: 10.1038/s41598-020-63093-6] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [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: 11/19/2019] [Accepted: 03/10/2020] [Indexed: 11/08/2022] Open
Abstract
Lignin is a heterogeneous aromatic polymer responsible for cell wall stiffness and protection from pathogen attack. However, lignin represents a bottleneck to biomass degradation due to its recalcitrance related to the natural cell wall resistance to release sugars for fermentation or further processing. A biological approach involving genetics and molecular biology was used to disrupt lignin pathway synthesis and decrease lignin deposition. Here, we imaged three-dimensional fragments of the petioles of wild type and C4H lignin mutant Arabidopsis thaliana plants by synchrotron cryo-ptychography. The three-dimensional images revealed the heterogeneity of vessels, parenchyma, and fibre cell wall morphologies, highlighting the relation between disturbed lignin deposition and vessel implosion (cell collapsing and obstruction of water flow). We introduce a new parameter to accurately define cell implosion conditions in plants, and we demonstrate how cryo-ptychographic X-ray computed tomography (cryo-PXCT) provides new insights for plant imaging in three dimensions to understand physiological processes.
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Affiliation(s)
- Carla C Polo
- Brazilian Synchrotron Light Laboratory (LNLS), Brazilian Center for Research in Energy and Materials (CNPEM), 13083-970, Campinas, SP, Brazil.
| | - Luciano Pereira
- Laboratory of Plant Physiology "Coaracy M. Franco", Center R&D in Ecophysiology and Biophysics, Agronomic Institute (IAC), Campinas, SP, Brazil
- Department of Plant Biology, Institute of Biology, P.O. Box 6109, University of Campinas (UNICAMP), 13083-970, Campinas, SP, Brazil
| | - Paulo Mazzafera
- Department of Plant Biology, Institute of Biology, P.O. Box 6109, University of Campinas (UNICAMP), 13083-970, Campinas, SP, Brazil
- Departament of Crop Science, College of Agriculture "Luiz de Queiroz", University of São Paulo (ESALQ-USP), CP 09, 13418-900, Piracicaba, SP, Brazil
| | - Denisele N A Flores-Borges
- Departament of Crop Science, College of Agriculture "Luiz de Queiroz", University of São Paulo (ESALQ-USP), CP 09, 13418-900, Piracicaba, SP, Brazil
| | - Juliana L S Mayer
- Departament of Crop Science, College of Agriculture "Luiz de Queiroz", University of São Paulo (ESALQ-USP), CP 09, 13418-900, Piracicaba, SP, Brazil
| | | | - Mirko Holler
- Paul Scherrer Institute, Villigen, PSI, Switzerland
| | - Mariane Barsi-Andreeta
- São Carlos Institute of Physics, University of São Paulo, PO Box 369, 13560-970, São Carlos, SP, Brazil
| | - Harry Westfahl
- Brazilian Synchrotron Light Laboratory (LNLS), Brazilian Center for Research in Energy and Materials (CNPEM), 13083-970, Campinas, SP, Brazil
| | - Florian Meneau
- Brazilian Synchrotron Light Laboratory (LNLS), Brazilian Center for Research in Energy and Materials (CNPEM), 13083-970, Campinas, SP, Brazil.
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d Oliveira RB, Carvalho CPDF, Polo CC, Dorighello GDG, Boschero AC, d Oliveira HCF, Collares-Buzato CB. Impaired compensatory beta-cell function and growth in response to high-fat diet in LDL receptor knockout mice. Int J Exp Pathol 2014; 95:296-308. [PMID: 24853046 PMCID: PMC4170972 DOI: 10.1111/iep.12084] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2013] [Accepted: 04/06/2014] [Indexed: 12/28/2022] Open
Abstract
In this study, we investigated the effect of low density lipoprotein receptor (LDLr) deficiency on gap junctional connexin 36 (Cx36) islet content and on the functional and growth response of pancreatic beta-cells in C57BL/6 mice fed a high-fat (HF) diet. After 60 days on regular or HF diet, the metabolic state and morphometric islet parameters of wild-type (WT) and LDLr-/- mice were assessed. HF diet-fed WT animals became obese and hypercholesterolaemic as well as hyperglycaemic, hyperinsulinaemic, glucose intolerant and insulin resistant, characterizing them as prediabetic. Also they showed a significant decrease in beta-cell secretory response to glucose. Overall, LDLr-/- mice displayed greater susceptibility to HF diet as judged by their marked cholesterolaemia, intolerance to glucose and pronounced decrease in glucose-stimulated insulin secretion. HF diet induced similarly in WT and LDLr-/- mice, a significant decrease in Cx36 beta-cell content as revealed by immunoblotting. Prediabetic WT mice displayed marked increase in beta-cell mass mainly due to beta-cell hypertrophy/replication. Nevertheless, HF diet-fed LDLr-/- mice showed no significant changes in beta-cell mass, but lower islet-duct association (neogenesis) and higher beta-cell apoptosis index were seen as compared to controls. The higher metabolic susceptibility to HF diet of LDLr-/- mice may be explained by a deficiency in insulin secretory response to glucose associated with lack of compensatory beta-cell expansion.
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Affiliation(s)
- Ricardo B d Oliveira
- Department of Histology and Embryology, University of Campinas (UNICAMP), Campinas, SP, Brazil
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Santos CR, Polo CC, Costa MCMF, Nascimento AFZ, Meza AN, Cota J, Hoffmam ZB, Honorato RV, Oliveira PSL, Goldman GH, Gilbert HJ, Prade RA, Ruller R, Squina FM, Wong DWS, Murakami MT. Mechanistic strategies for catalysis adopted by evolutionary distinct family 43 arabinanases. J Biol Chem 2014; 289:7362-73. [PMID: 24469445 DOI: 10.1074/jbc.m113.537167] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Arabinanases (ABNs, EC 3.2.1.99) are promising catalysts for environmentally friendly biomass conversion into energy and chemicals. These enzymes catalyze the hydrolysis of the α-1,5-linked L-arabinofuranoside backbone of plant cell wall arabinans releasing arabino-oligosaccharides and arabinose, the second most abundant pentose in nature. In this work, new findings about the molecular mechanisms governing activation, functional differentiation, and catalysis of GH43 ABNs are presented. Biophysical, mutational, and biochemical studies with the hyperthermostable two-domain endo-acting ABN from Thermotoga petrophila (TpABN) revealed how some GH43 ABNs are activated by calcium ions via hyperpolarization of the catalytically relevant histidine and the importance of the ancillary domain for catalysis and conformational stability. On the other hand, the two GH43 ABNs from rumen metagenome, ARN2 and ARN3, presented a calcium-independent mechanism in which sodium is the most likely substituent for calcium ions. The crystal structure of the two-domain endo-acting ARN2 showed that its ability to efficiently degrade branched substrates is due to a larger catalytic interface with higher accessibility than that observed in other ABNs with preference for linear arabinan. Moreover, crystallographic characterization of the single-domain exo-acting ARN3 indicated that its cleavage pattern producing arabinose is associated with the chemical recognition of the reducing end of the substrate imposed by steric impediments at the aglycone-binding site. By structure-guided rational design, ARN3 was converted into a classical endo enzyme, confirming the role of the extended Arg(203)-Ala(230) loop in determining its action mode. These results reveal novel molecular aspects concerning the functioning of GH43 ABNs and provide new strategies for arabinan degradation.
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