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Nyholm SV, McFall-Ngai MJ. A lasting symbiosis: how the Hawaiian bobtail squid finds and keeps its bioluminescent bacterial partner. Nat Rev Microbiol 2021; 19:666-679. [PMID: 34089010 PMCID: PMC8440403 DOI: 10.1038/s41579-021-00567-y] [Citation(s) in RCA: 62] [Impact Index Per Article: 20.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/15/2021] [Indexed: 01/08/2023]
Abstract
For more than 30 years, the association between the Hawaiian bobtail squid, Euprymna scolopes, and the bioluminescent bacterium Vibrio fischeri has been studied as a model system for understanding the colonization of animal epithelia by symbiotic bacteria. The squid-vibrio light-organ system provides the exquisite resolution only possible with the study of a binary partnership. The impact of this relationship on the partners' biology has been broadly characterized, including their ecology and evolutionary biology as well as the underlying molecular mechanisms of symbiotic dynamics. Much has been learned about the factors that foster initial light-organ colonization, and more recently about the maturation and long-term maintenance of the association. This Review synthesizes the results of recent research on the light-organ association and also describes the development of new horizons for E. scolopes as a model organism that promises to inform biology and biomedicine about the basic nature of host-microorganism interactions.
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Affiliation(s)
- Spencer V Nyholm
- Department of Molecular and Cell Biology, University of Connecticut, Storrs, CT, USA.
| | - Margaret J McFall-Ngai
- Pacific Biosciences Research Center, Kewalo Marine Laboratory, University of Hawai'i at Mānoa, Honolulu, HI, USA.
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A lasting symbiosis: how Vibrio fischeri finds a squid partner and persists within its natural host. Nat Rev Microbiol 2021; 19:654-665. [PMID: 34089008 DOI: 10.1038/s41579-021-00557-0] [Citation(s) in RCA: 59] [Impact Index Per Article: 19.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/31/2021] [Indexed: 01/10/2023]
Abstract
As our understanding of the human microbiome progresses, so does the need for natural experimental animal models that promote a mechanistic understanding of beneficial microorganism-host interactions. Years of research into the exclusive symbiosis between the Hawaiian bobtail squid, Euprymna scolopes, and the bioluminescent bacterium Vibrio fischeri have permitted a detailed understanding of those bacterial genes underlying signal exchange and rhythmic activities that result in a persistent, beneficial association, as well as glimpses into the evolution of symbiotic competence. Migrating from the ambient seawater to regions deep inside the light-emitting organ of the squid, V. fischeri experiences, recognizes and adjusts to the changing environmental conditions. Here, we review key advances over the past 15 years that are deepening our understanding of these events.
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Moeini M, Lu X, Avti PK, Damseh R, Bélanger S, Picard F, Boas D, Kakkar A, Lesage F. Compromised microvascular oxygen delivery increases brain tissue vulnerability with age. Sci Rep 2018; 8:8219. [PMID: 29844478 PMCID: PMC5974237 DOI: 10.1038/s41598-018-26543-w] [Citation(s) in RCA: 54] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2018] [Accepted: 05/16/2018] [Indexed: 11/22/2022] Open
Abstract
Despite the possible role of impaired cerebral tissue oxygenation in age-related cognition decline, much is still unknown about the changes in brain tissue pO2 with age. Using a detailed investigation of the age-related changes in cerebral tissue oxygenation in the barrel cortex of healthy, awake aged mice, we demonstrate decreased arteriolar and tissue pO2 with age. These changes are exacerbated after middle-age. We further uncovered evidence of the presence of hypoxic micro-pockets in the cortex of awake old mice. Our data suggests that from young to middle-age, a well-regulated capillary oxygen supply maintains the oxygen availability in cerebral tissue, despite decreased tissue pO2 next to arterioles. After middle-age, due to decreased hematocrit, reduced capillary density and higher capillary transit time heterogeneity, the capillary network fails to compensate for larger decreases in arterial pO2. The substantial decrease in brain tissue pO2, and the presence of hypoxic micro-pockets after middle-age are of significant importance, as these factors may be related to cognitive decline in elderly people.
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Affiliation(s)
- Mohammad Moeini
- Biomedical Engineering Institute, École Polytechnique de Montréal, Montréal, QC, Canada.,Research Center of Montreal Heart Institute, Montréal, QC, Canada.,Department of Chemistry, McGill University, Montréal, QC, Canada
| | - Xuecong Lu
- Biomedical Engineering Institute, École Polytechnique de Montréal, Montréal, QC, Canada.,Research Center of Montreal Heart Institute, Montréal, QC, Canada
| | - Pramod K Avti
- Biomedical Engineering Institute, École Polytechnique de Montréal, Montréal, QC, Canada.,Research Center of Montreal Heart Institute, Montréal, QC, Canada.,Department of Biophysics, Postgraduate Institute of Medical Education and Research, Chandigarh, India
| | - Rafat Damseh
- Biomedical Engineering Institute, École Polytechnique de Montréal, Montréal, QC, Canada
| | - Samuel Bélanger
- Biomedical Engineering Institute, École Polytechnique de Montréal, Montréal, QC, Canada.,Research Center of Montreal Heart Institute, Montréal, QC, Canada
| | - Frédéric Picard
- Centre de Recherche de l'Institut Universitaire de Cardiologie et Pneumologie de Québec (IUCPQ), Québec, QC, Canada
| | - David Boas
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA.,Biomedical Engineering Department, College of Engineering, Boston University, Boston, MA, USA
| | - Ashok Kakkar
- Department of Chemistry, McGill University, Montréal, QC, Canada
| | - Frédéric Lesage
- Biomedical Engineering Institute, École Polytechnique de Montréal, Montréal, QC, Canada. .,Research Center of Montreal Heart Institute, Montréal, QC, Canada.
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Villena A, Vidal L, Díaz F, Pérez De Vargas I. Stereological changes in the capillary network of the aging dorsal lateral geniculate nucleus. THE ANATOMICAL RECORD. PART A, DISCOVERIES IN MOLECULAR, CELLULAR, AND EVOLUTIONARY BIOLOGY 2003; 274:857-61. [PMID: 12923896 DOI: 10.1002/ar.a.10100] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
In this work we studied the effect of aging on the capillaries of the dorsal lateral geniculate nucleus in 3-, 18-, 24-, and 28-month-old rats. The parameters analyzed were the capillary profile density, capillary volume fraction, length and surface area per unit volume, and capillary average diameter. The quantitative analysis showed in all parameters an increase between 3 and 18 months, and a significant decrease in capillary volume fraction (-18.75%) and diameter (-5.5%) between 18 and 24 months. No changes from 24 months onwards were observed. The increase observed in capillary profile density and capillary volume fraction between 3 and 18 months may indicate an increase of the capillary network. Furthermore, we observed an increase in the length and surface area per unit volume, which we interpret as an expansion of the exchange surface between blood and nerve tissue. The reduction in the capillary parameters that takes place between 18 and 24 months is slight, and may indicate the onset of decline characteristic of aging.
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Affiliation(s)
- Alicia Villena
- Department of Histology and Pathology, School of Medicine, Campus de Teatinos, Málaga, Spain.
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Abstract
The hearts of rats were irradiated locally to single doses of X-ray in the range of 20-50 Gy. The mean latency period between treatment and death ranged from 550 +/- 12 days to 260 +/- 13 days for animals irradiated with doses of 20 and 50 Gy. The growth rate and cardiac output was followed for a period of 10 months after treatment. In irradiated animals, there was a delay in growth and the rate of growth plateaued at approximately 6 months after treatment. Cardiac output was measured by an external counting technique. There was a general decline in cardiac output at time intervals from 4 to 10 months after irradiation. This reduction in cardiac output was dose-dependent. A single dose of 30 Gy reduced the cardiac output to approximately 70% of the control value, 6 months after irradiation.
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Wilkinson JH, Hopewell JW, Reinhold HS. A quantitative study of age-related changes in the vascular architecture of the rat cerebral cortex. Neuropathol Appl Neurobiol 1981; 7:451-62. [PMID: 7329517 DOI: 10.1111/j.1365-2990.1981.tb00245.x] [Citation(s) in RCA: 35] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
A quantitative study of age related changes in the vascular architecture of the rat cerebral cortex is described. A special vessel-filling technique, which allowed the simultaneous fixation of the vasculature, aided the identification of the vessels in histological sections. Vascular parameters, which included the total number of vessel fragments, a blood volume and a vessel wall-surface area index were obtained using a Quantimet 720 shape-analysing computer. In animals aged 13-83 weeks, there was an increase in the above vascular parameters which could mainly be attributed to an increase in the number of vessels with a diameter greater than 8 micrometers. In very old rats, aged 124 weeks, the vascularity of the cerebral cortex was severely reduced. These changes, which are very similar to those reported in the ageing human cerebral cortex, may be explained by either direct or indirect effects on the cerebral vasculature. Possible mechanisms are discussed in relation to similar changes observed in the cerebral vasculature after several different insults.
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