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McMillan HM. In the face of climate change, will trees be…shorter? Plant Physiol 2024; 194:1279-1281. [PMID: 37962932 PMCID: PMC10904339 DOI: 10.1093/plphys/kiad610] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2023] [Revised: 11/07/2023] [Accepted: 11/08/2023] [Indexed: 11/15/2023]
Affiliation(s)
- Hannah M McMillan
- Assistant Features Editor, Plant Physiology, American Society of Plant Biologists
- Department of Biology, Duke University, Durham, NC 27708, USA
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McMillan HM. New receptors for common MAMPs: Can wild relatives save citrus from disease? Plant Physiol 2023; 193:162-165. [PMID: 37221322 PMCID: PMC10469516 DOI: 10.1093/plphys/kiad306] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/08/2023] [Revised: 05/15/2023] [Accepted: 05/15/2023] [Indexed: 05/25/2023]
Affiliation(s)
- Hannah M McMillan
- Assistant Features Editor, Plant Physiology, American Society of Plant Biologists, USA
- Department of Biology, Duke University, Durham, NC 27708, USA
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McMillan HM. Plants target gut microbes to reduce insect herbivore damage. Proc Natl Acad Sci U S A 2023; 120:e2308568120. [PMID: 37379352 DOI: 10.1073/pnas.2308568120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/30/2023] Open
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McMillan HM. Sec14-like proteins to the rescue: Improving plant performance in low phosphate conditions. Plant Physiol 2023:7152938. [PMID: 37144824 PMCID: PMC10400019 DOI: 10.1093/plphys/kiad265] [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] [Subscribe] [Scholar Register] [Received: 04/18/2023] [Revised: 04/25/2023] [Accepted: 04/25/2023] [Indexed: 05/06/2023]
Affiliation(s)
- Hannah M McMillan
- Assistant Features Editor, Plant Physiology, American Society of Plant Biologists, USA
- Department of Biology, Duke University, Durham, NC 27708, USA
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Rogers NMK, McCumber AW, McMillan HM, McNamara RP, Dittmer DP, Kuehn MJ, Hendren CO, Wiesner MR. Comparative electrokinetic properties of extracellular vesicles produced by yeast and bacteria. Colloids Surf B Biointerfaces 2023; 225:113249. [PMID: 36905832 PMCID: PMC10085849 DOI: 10.1016/j.colsurfb.2023.113249] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2022] [Revised: 02/13/2023] [Accepted: 03/04/2023] [Indexed: 03/08/2023]
Abstract
Extracellular vesicles (EVs) are nano-sized, biocolloidal proteoliposomes that have been shown to be produced by all cell types studied to date and are ubiquitous in the environment. Extensive literature on colloidal particles has demonstrated the implications of surface chemistry on transport behavior. Hence, one may anticipate that physicochemical properties of EVs, particularly surface charge-associated properties, may influence EV transport and specificity of interactions with surfaces. Here we compare the surface chemistry of EVs as expressed by zeta potential (calculated from electrophoretic mobility measurements). The zeta potentials of EVs produced by Pseudomonas fluorescens, Staphylococcus aureus, and Saccharomyces cerevisiae were largely unaffected by changes in ionic strength and electrolyte type, but were affected by changes in pH. The addition of humic acid altered the calculated zeta potential of the EVs, especially for those from S. cerevisiae. Differences in zeta potential were compared between EVs and their respective parent cell with no consistent trend emerging; however, significant differences were discovered between the different cell types and their EVs. These findings imply that, while EV surface charge (as estimated from zeta potential) is relatively insensitive to the evaluated environmental conditions, EVs from different organisms can differ regarding which conditions will cause colloidal instability.
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Affiliation(s)
- Nicholas M K Rogers
- Department of Mechanical Engineering, Tel Aviv University, Tel Aviv 69978, Israel; Porter School of Earth and Environmental Studies, Tel Aviv University, Tel Aviv 69978, Israel.
| | - Alexander W McCumber
- Department of Environmental Sciences and Engineering, University of North Carolina Chapel Hill, Chapel Hill, NC, USA
| | - Hannah M McMillan
- Department of Molecular Genetics and Microbiology, Duke University, Durham, NC, USA
| | - Ryan P McNamara
- Department of Microbiology and Immunology, University of North Carolina Chapel Hill, Chapel Hill, NC, USA
| | - Dirk P Dittmer
- Department of Microbiology and Immunology, University of North Carolina Chapel Hill, Chapel Hill, NC, USA
| | - Meta J Kuehn
- Department of Biochemistry, Duke University, Durham, NC, USA; Department of Molecular Genetics and Microbiology, Duke University, Durham, NC, USA
| | - Christine Ogilvie Hendren
- Center for the Environmental Implications of Nanotechnology, Duke University, Durham, NC, USA; Department of Geological and Environmental Sciences, Appalachian State University, Boone, NC, USA; Research Institute for Environment, Energy and Economics, Appalachian State University, Boone, NC, USA
| | - Mark R Wiesner
- Department of Civil & Environmental Engineering, Duke University, Durham, NC, USA; Center for the Environmental Implications of Nanotechnology, Duke University, Durham, NC, USA
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McMillan HM, Kuehn MJ. The extracellular vesicle generation paradox: a bacterial point of view. EMBO J 2021; 40:e108174. [PMID: 34636061 PMCID: PMC8561641 DOI: 10.15252/embj.2021108174] [Citation(s) in RCA: 44] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2021] [Revised: 06/29/2021] [Accepted: 07/28/2021] [Indexed: 12/23/2022] Open
Abstract
All bacteria produce secreted vesicles that carry out a variety of important biological functions. These extracellular vesicles can improve adaptation and survival by relieving bacterial stress and eliminating toxic compounds, as well as by facilitating membrane remodeling and ameliorating inhospitable environments. However, vesicle production comes with a price. It is energetically costly and, in the case of colonizing pathogens, it elicits host immune responses, which reduce bacterial viability. This raises an interesting paradox regarding why bacteria produce vesicles and begs the question as to whether the benefits of producing vesicles outweigh their costs. In this review, we discuss the various advantages and disadvantages associated with Gram-negative and Gram-positive bacterial vesicle production and offer perspective on the ultimate score. We also highlight questions needed to advance the field in determining the role for vesicles in bacterial survival, interkingdom communication, and virulence.
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Affiliation(s)
- Hannah M McMillan
- Department of Molecular Genetics and MicrobiologyDuke UniversityDurhamNCUSA
| | - Meta J Kuehn
- Department of BiochemistryDuke UniversityDurhamNCUSA
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McMillan HM, Rogers N, Wadle A, Hsu-Kim H, Wiesner MR, Kuehn MJ, Hendren CO. Microbial vesicle-mediated communication: convergence to understand interactions within and between domains of life. Environ Sci Process Impacts 2021; 23:664-677. [PMID: 33899070 DOI: 10.1039/d1em00022e] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
All cells produce extracellular vesicles (EVs). These biological packages contain complex mixtures of molecular cargo and have a variety of functions, including interkingdom communication. Recent discoveries highlight the roles microbial EVs may play in the environment with respect to interactions with plants as well as nutrient cycling. These studies have also identified molecules present within EVs and associated with EV surfaces that contribute to these functions. In parallel, studies of engineered nanomaterials have developed methods to track and model small particle behavior in complex systems and measure the relative importance of various surface features on transport and function. While studies of EV behavior in complex environmental conditions have not yet employed transdisciplinary approaches, it is increasingly clear that expertise from disparate fields will be critical to understand the role of EVs in these systems. Here, we outline how the convergence of biology, soil geochemistry, and colloid science can both develop and address questions surrounding the basic principles governing EV-mediated interkingdom interactions.
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Affiliation(s)
- Hannah M McMillan
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, NC 27710, USA
| | - Nicholas Rogers
- Department of Civil and Environmental Engineering, Duke University, Durham, NC 27708, USA
| | - Austin Wadle
- Department of Civil and Environmental Engineering, Duke University, Durham, NC 27708, USA
| | - Heileen Hsu-Kim
- Department of Civil and Environmental Engineering, Duke University, Durham, NC 27708, USA
| | - Mark R Wiesner
- Department of Civil and Environmental Engineering, Duke University, Durham, NC 27708, USA
| | - Meta J Kuehn
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, NC 27710, USA and Department of Biochemistry, Duke University Medical Center, Durham, NC 27710, USA
| | - Christine Ogilvie Hendren
- Department of Civil and Environmental Engineering, Duke University, Durham, NC 27708, USA and Department of Geological and Environmental Sciences, Appalachian State University, Boone, NC 28608, USA.
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McMillan HM, Zebell SG, Ristaino JB, Dong X, Kuehn MJ. Protective plant immune responses are elicited by bacterial outer membrane vesicles. Cell Rep 2021; 34:108645. [PMID: 33472073 PMCID: PMC8158063 DOI: 10.1016/j.celrep.2020.108645] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Revised: 10/26/2020] [Accepted: 12/21/2020] [Indexed: 12/22/2022] Open
Abstract
Bacterial outer membrane vesicles (OMVs) perform a variety of functions in bacterial survival and virulence. In mammalian systems, OMVs activate immune responses and are exploited as vaccines. However, little work has focused on the interactions of OMVs with plant hosts. Here, we report that OMVs from Pseudomonas syringae and P. fluorescens activate plant immune responses that protect against bacterial and oomycete pathogens. OMV-mediated immunomodulatory activity from these species displayed different sensitivity to biochemical stressors, reflecting differences in OMV content. Importantly, OMV-mediated plant responses are distinct from those triggered by conserved bacterial epitopes or effector molecules alone. Our study shows that OMV-induced protective immune responses are independent of the T3SS and protein, but that OMV-mediated seedling growth inhibition largely depends on proteinaceous components. OMVs provide a unique opportunity to understand the interplay between virulence and host response strategies and add a new dimension to consider in host-microbe interactions. The role that bacterial outer membrane vesicles (OMVs) play in plant-microbe interactions is poorly characterized. McMillan et al. show that OMVs elicit plant immune responses that protect against pathogens. This study also reveals a use for OMVs as tools to probe the plant immune system.
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Affiliation(s)
- Hannah M McMillan
- Department of Molecular Genetics and Microbiology, Duke University, Durham, NC 27710, USA
| | - Sophia G Zebell
- Howard Hughes Medical Institute, Department of Biology, Duke University, Durham, NC 27708, USA
| | - Jean B Ristaino
- Department of Entomology and Plant Pathology, North Carolina State University, Raleigh, NC 27695, USA
| | - Xinnian Dong
- Howard Hughes Medical Institute, Department of Biology, Duke University, Durham, NC 27708, USA
| | - Meta J Kuehn
- Department of Molecular Genetics and Microbiology, Duke University, Durham, NC 27710, USA; Department of Biochemistry, Duke University, Durham, NC 27710, USA.
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McMillan HM, O'Carroll H, Lambert JS, Grundy KB, O'Reilly M, Lennon B, Collins C, Walsh TA, Geary MP, Cafferkey MT. Screening for Chlamydia trachomatis in asymptomatic women attending outpatient clinics in a large maternity hospital in Dublin, Ireland. Sex Transm Infect 2006; 82:503-5. [PMID: 16854994 PMCID: PMC2563860 DOI: 10.1136/sti.2006.020990] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [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: 11/04/2022] Open
Abstract
BACKGROUND Chlamydia trachomatis can cause a sexually transmitted infection, which, untreated, may result in considerable morbidity. METHODS A prevalence study was conducted for C trachomatis using nucleic acid amplification technology in asymptomatic women, and certain risk factors that may be used to direct future screening strategies were assessed. RESULTS The study population comprised 945 asymptomatic women, of whom 783 were attending antenatal clinics, 91 were attending infertility clinics and 71 were attending family planning clinics. An overall C trachomatis prevalence of 3.7% (35/945) was found, with the highest prevalence of 11.2% (22/196) in Irish single women aged <25 years. Logistic regression analysis showed that single status and age <25 years were independent, statistically significant predictors of C trachomatis infection. CONCLUSION These results support routine screening of asymptomatic women who are sexually active and aged <25 years. An opportunist active screening of all sexually active women independent of age should be additionally considered if resources permit.
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Affiliation(s)
- H M McMillan
- Department of Obstetrics and Gynaecology, Rotunda Hospital, Dublin, Ireland
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McMillan HM, Salman R, Khan MF, McAnena O, O'Connor RD. An ominous inguinal hernia. Ir J Med Sci 2004; 173:57. [PMID: 15732240 DOI: 10.1007/bf02914528] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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