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Glenn Yannic Martin-Hugues St-Laurent Joaquin Ortego Joëlle Taillon Alexandre Beauchemin Louis Bernatchez Christian Dussault Steeve D. Côté 《Conservation Genetics》2016,17(2):437-453
Genetic diversity is a key parameter to delineate management units, but many organisms also display ecological characteristics that may reflect potential local adaptations. Here, we used ecological and genetic information to delineate management units for a complex system involving several ecotypes of caribou (Rangifer tarandus) from Québec and Labrador, eastern Canada. We genotyped 560 caribou at 16 microsatellite loci and used three Bayesian clustering methods to spatially delineate and characterize genetic structure across the landscape. The different approaches employed did not converge on the same solution, and differed in the number of inferred genetic clusters that best fit the dataset but also in the spatial distribution of genetic variation. We reconciled variability among the methods using a synthetic approach that considers the sum of the partitions obtained by each of them and retrieved six genetically distinct groups that differ in their spatial extent across the range of caribou in the study area. These genetic groups are not consistent with the presently defined ecological designations for this species. Combining both genetic and ecological criteria, we distinguished eight independent management units. Overall, the management units we propose should be the focus of conservation and management actions aimed to maximize genetic and ecological diversity and ensure the persistence of caribou populations inhabiting increasingly disturbed landscapes. 相似文献
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Etienne X. Keller Vincent de Coninck Marie Audouin Steeve Doizi Dominique Bazin Michel Daudon Olivier Traxer 《Journal of biophotonics》2019,12(4)
Urinary stones can be readily disintegrated by Holmium:YAG laser (Holmium laser lithotripsy), resulting in a mixture of small stone dust particles, which will spontaneously evacuate with urine and larger residual fragments (RF) requiring mechanical retrieval. Differences between fragments and dust have not been well characterized. Also, it remains unknown how the recently introduced “Moses technology” may alter stone disintegration products. Three complementary analytical techniques have been used in this study to offer an in‐depth characterization of disintegration products after in vitro Holmium laser lithotripsy: stereoscopic microscopy, scanning electron microscopy and Fourier‐transform infrared spectroscopy. Dust was separated from fragments based on its floating ability in saline irrigation. Depending on initial crystalline constituents, stone dust either conserved attributes found in larger RFs or showed changes in crystalline organization. These included conversion of calcium oxalate dihydrate towards calcium oxalate monohydrate, changes in carbapatite spectra towards an amorphous phase, changes of magnesium ammonium phosphate towards a differing amorphous and crystalline phase and the appearance of hydroxyapatite on brushite fragments. Comparatively, “Moses technology” produced more pronounced changes. These findings provide new insights suggesting a photothermal effect occurring in Holmium laser lithotripsy. Figure: Appearance of hydroxyapatite hexagons on stone dust collected after Holmium laser lithotripsy of a brushite stone using “Moses technology.” 相似文献
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Kwan Tat S Padrines M Théoleyre S Heymann D Fortun Y 《Cytokine & growth factor reviews》2004,15(1):49-60
All osteogenic cells (osteoclasts, osteoblasts) contribute individually to bone remodeling. Their cellular interactions control their cellular activities and the bone remodeling intensity. These interactions can be established either through a cell-cell contact, involving molecules of the integrin family, or by the release of many polypeptidic factors and/or their soluble receptor chains. These factors can act directly on osteogenic cells and their precursors to control differentiation, formation and functions (matrix formation, mineralization, resorption...). Here, we present the involvement of three groups of cytokines which seem to be of particular importance in bone physiology: interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-alpha) (TNF-alpha)/IL-1, and the more recently known triad osteoprotegerin (OPG)/receptor activator of NF-kappaB (RANK)/RANK ligand (RANKL). The interactions between these three groups are presented within the framework of bone resorption pathophysiology such as tumor associated osteolysis. The central role of the OPG/RANK/RANKL triad is pointed out. 相似文献
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We enriched in CO2 the canopy of 14 broad-leaved trees in a species-rich, ca. 30-m-tall forest in NW Switzerland to test whether elevated CO2 reduces water use in mature forest trees. Measurements of sap flux density (JS) were made prior to CO2 enrichment (summer 2000) and throughout the first whole growing season of CO2 exposure (2001) using the constant heat-flow technique. The short-term responses of sap flux to brief (1.5–3 h) interruptions of CO2 enrichment were also examined. There were no significant a priori differences in morphological and physiological traits between trees which were later exposed to elevated CO2 (n=14) and trees later used as controls (n=19). Over the entire growing season, CO2 enrichment resulted in an average 10.7% reduction in mean daily JS across all species compared to control trees. Responses were most pronounced in Carpinus, Acer, Prunus and Tilia, smaller in Quercus and close to zero in Fagus trees. The JS of treated trees significantly increased by 7% upon transient exposure to ambient CO2 concentrations at noon. Hence, responses of the different species were, in the short term, similar in magnitude to those observed over the whole season (though opposite because of the reversed treatment). The reductions in mean JS of CO2-enriched trees were high (22%) under conditions of low evaporative demand (vapour pressure deficit, VPD <5 hPa) and small (2%) when mean daily VPD was greater than 10 hPa. During a relatively dry period, the effect of elevated CO2 on JS even appeared to be reversed. These results suggest that daily water savings by CO2-enriched trees may have accumulated to a significantly improved water status by the time when control trees were short of soil moisture. Our data indicate that the magnitude of CO2 effects on stand transpiration will depend on rainfall regimes and the relative abundance of the different species, being more pronounced under humid conditions and in stands dominated by species such as Carpinus and negligible in mono-specific Fagus forests. 相似文献
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Mason T. MacDonald Rajasekaran R. Lada Alex I. Martynenko Martine Dorais Steeve Pepin Yves Desjardins 《Trees - Structure and Function》2010,24(5):879-886
Post-harvest needle abscission is a major challenge for Christmas tree and greenery industries. It was hypothesized that ethylene
triggers abscission in balsam fir. Three experiments were conducted to test this hypothesis. In experiment 1, 70 balsam fir
branches were collected, placed in water, and ethylene evolution was observed over time. In experiment 2, a 2 × 5 factorial
experiment was designed to determine the effect of exogenous ethylene and an ethylene receptor blocker, 1-methylcyclopropene
(1-MCP), on needle abscission. In experiment 3, a 2 × 6 factorial experiment was designed to determine the effect of exogenous
ethylene and an ethylene inhibitor, aminoethoxyvinylglycine (AVG), on needle abscission. It was found that ethylene evolution
was the highest 1–2 days prior to needle abscission, which was consistent in untreated branches and branches exposed to exogenous
ethylene. Exposure to exogenous ethylene significantly decreased needle retention by 63%. When ethylene receptors were blocked
by 1-MCP, needle retention increased by 147% despite the presence of ethylene and increased by 73% in the absence of ethylene
when compared to the respective controls. When endogenous ethylene synthesis was inhibited by AVG, there was no improvement
in needle retention in the presence of ethylene, but there was a 113% increase in needle retention in the absence of exogenous
ethylene. Ethylene is strongly implicated as the signal triggering abscission in root-detached balsam fir. 相似文献
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M. Anouk Simard Tim Coulson André Gingras Steeve D. Co̧té 《The Journal of wildlife management》2010,74(8):1671-1685
ABSTRACT Dynamics of herbivore populations can be influenced both by density-dependent processes and climate. We used age-at-harvest data for adult female white-tailed deer (Odocoileus virginianus) collected over 23 years to estimate survival and reproduction by age class and to identify effects of environmental factors. The study population was located on Anticosti Island (QC, Canada), at the northern limit of the species' range; the population was at high density, and the landscape had scarce forage and abundant snow during winter. Despite severe environmental conditions, population growth apparently increased during the study; adult survival was similar to other populations, although reproduction appeared lower. Winter severity was not related to survival, but density affected adult female survival. Density at estrus was the main factor influencing reproduction of 2- and 3–4-year-olds and also affected reproduction of prime-aged females (5–9-yr-olds), but not of older females. Reproductive rate of younger females was influenced by environmental conditions in autumn, such as high density or snow conditions that limited forage availability. Reproductive success of 5–9- and ≥10-year-old females appeared dependent on spring conditions favoring high-quality forage, probably through effects on neonatal survival. Relative to other studies on northern ungulates, demographic processes in our study appeared to be more affected by autumn and spring climate, in addition to population density, than by winter climate. We thus propose that population density, as well as autumn and spring climate, should be considered in management strategies. Harvest data offered a unique opportunity to study forest ungulates, for which individual monitoring is rarely possible. 相似文献
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The lipid droplet binding domain of hepatitis C virus core protein is a major determinant for efficient virus assembly 总被引:6,自引:0,他引:6
Shavinskaya A Boulant S Penin F McLauchlan J Bartenschlager R 《The Journal of biological chemistry》2007,282(51):37158-37169
Hepatitis C virus core protein forms the viral capsid and is targeted to lipid droplets (LDs) by its domain 2 (D2). By using a comparative analysis of two hepatitis C virus genomes (JFH1 and Jc1) differing in their level of virus production in cultured human hepatoma cells, we demonstrate that the core of the genotype 2a isolate J6 that is present in Jc1 mediates efficient assembly and release of infectious virions. Mapping studies identified a single amino acid residue in D2 as a major determinant for enhanced assembly and release of infectious Jc1 particles. Confocal microscopy analyses demonstrate that core protein in JFH1-replicating cells co-localizes perfectly with LDs and induces their accumulation in the perinuclear area, whereas no such accumulation of LDs and only a partial co-localization of core and LDs were found with the Jc1 genome. By using a fluorescence recovery after photobleaching assay, we found that green fluorescent protein-tagged D2 variants are mobile on LDs and that J6- and JFH1-D2 differ in their mobility. Taken together, our results demonstrate that the binding strength of the D2 domain of core for LDs is crucial for determining the efficiency of virus assembly. 相似文献