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101.
Maud Laurent Melanie Dickie Marcus Becker Robert Serrouya Stan Boutin 《The Journal of wildlife management》2021,85(2):340-353
Understanding how landscape change influences the distribution and densities of species, and the consequences of these changes, is a central question in modern ecology. The distribution of white-tailed deer (Odocoileus virginianus) is expanding across North America, and in some areas, this pattern has led to an increase in predators and consequently higher predation rates on woodland caribou (Rangifer tarandus caribou)—an alternate prey species that is declining across western Canada. Understanding the factors influencing deer distribution has therefore become important for effective conservation of caribou in Canada. Changing climate and anthropogenic landscape alteration are hypothesized to facilitate white-tailed deer expansion. Yet, climate and habitat alteration are spatiotemporally correlated, making these factors difficult to isolate. Our study evaluates the relative effects of snow conditions and human-modified habitat (habitat alteration) across space on white-tailed deer presence and relative density. We modeled deer response to snow depth and anthropogenic habitat alteration across a large latitudinal gradient (49° to 60°) in Alberta, Canada, using motion-sensitive camera data collected in winter and spring from 2015 to 2019. Deer distribution in winter and spring were best explained by models including both snow depth and habitat alteration. Sites with shallower snow had higher deer presence regardless of latitude. Increased habitat alteration increased deer presence in the northern portion of the study area only. Winter deer density was best explained by snow depth only, whereas spring density was best explained by both habitat alteration and the previous winter's snow depth. Our results suggest that limiting future habitat alteration or restoring habitat can alter deer distribution, thereby potentially slowing or reversing expansion, but that climate plays a significant role beyond what managers can influence. © 2020 The Wildlife Society. 相似文献
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Stéphane Guyot Laurence Pottier Lucie Bertheau Jennifer Dumont Eminence Dorelle Hondjuila Miokono Sébastien Dupont Mélanie Ragon Emmanuel Denimal Ambroise Marin John E. Hallsworth Laurent Beney Patrick Gervais 《Microbial biotechnology》2021,14(4):1445-1461
Although mechanisms involved in response of Saccharomyces cerevisiae to osmotic challenge are well described for low and sudden stresses, little is known about how cells respond to a gradual increase of the osmotic pressure (reduced water activity; aw) over several generations as it could encounter during drying in nature or in food processes. Using glycerol as a stressor, we propagated S. cerevisiae through a ramp of the osmotic pressure (up to high molar concentrations to achieve testing-to-destruction) at the rate of 1.5 MPa day-1 from 1.38 to 58.5 MPa (0.990–0.635 aw). Cultivability (measured at 1.38 MPa and at the harvest osmotic pressure) and glucose consumption compared with the corresponding sudden stress showed that yeasts were able to grow until about 10.5 MPa (0.926 aw) and to survive until about 58.5 MPa, whereas glucose consumption occurred until 13.5 MPa (about 0.915 aw). Nevertheless, the ramp conferred an advantage since yeasts harvested at 10.5 and 34.5 MPa (0.778 aw) showed a greater cultivability than glycerol-shocked cells after a subsequent shock at 200 MPa (0.234 aw) for 2 days. FTIR analysis revealed structural changes in wall and proteins in the range 1.38–10.5 MPa, which would be likely to be involved in the resistance at extreme osmotic pressure. 相似文献
104.
Hlne Bouvrais Laurent Chesneau Yann Le Cunff Danielle Fairbrass Nina Soler Sylvain Pastezeur Thierry Pcot Charles Kervrann Jacques Pcraux 《EMBO reports》2021,22(5)
In Caenorhabditis elegans zygote, astral microtubules generate forces essential to position the mitotic spindle, by pushing against and pulling from the cortex. Measuring microtubule dynamics there, we revealed the presence of two populations, corresponding to pulling and pushing events. It offers a unique opportunity to study, under physiological conditions, the variations of both spindle‐positioning forces along space and time. We propose a threefold control of pulling force, by polarity, spindle position and mitotic progression. We showed that the sole anteroposterior asymmetry in dynein on‐rate, encoding pulling force imbalance, is sufficient to cause posterior spindle displacement. The positional regulation, reflecting the number of microtubule contacts in the posterior‐most region, reinforces this imbalance only in late anaphase. Furthermore, we exhibited the first direct proof that dynein processivity increases along mitosis. It reflects the temporal control of pulling forces, which strengthens at anaphase onset following mitotic progression and independently from chromatid separation. In contrast, the pushing force remains constant and symmetric and contributes to maintaining the spindle at the cell centre during metaphase. 相似文献
105.
Keymanthri Moodley Stuart Rennie Frieda Behets Adetayo Emmanuel Obasa Robert Yemesi Laurent Ravez Patrick Kayembe Darius Makindu Alwyn Mwinga Walter Jaoko 《Developing world bioethics》2021,21(1):36-43
The COVID‐19 pandemic has raised important universal public health challenges. Conceiving ethical responses to these challenges is a public health imperative but must take context into account. This is particularly important in sub‐Saharan Africa (SSA). In this paper, we examine how some of the ethical recommendations offered so far in high‐income countries might appear from a SSA perspective. We also reflect on some of the key ethical challenges raised by the COVID‐19 pandemic in low‐income countries suffering from chronic shortages in health care resources, and chronic high morbidity and mortality from non‐COVID‐19 causes. A parallel is drawn between the distribution of severity of COVID‐19 disease and the classic “Fortune at the bottom of the pyramid” model that is relevant in SSA. Focusing allocation of resources during COVID‐19 on the ‘thick’ part of the pyramid in Low‐to‐Middle Income Countries (LMICs) could be ethically justified on utilitarian and social justice grounds, since it prioritizes a large number of persons who have been economically and socially marginalized. During the pandemic, importing allocation frameworks focused on the apex of the pyramid from the global north may therefore not always be appropriate. In a post‐COVID‐19 world, we need to think strategically about how health care systems can be financed and structured to ensure broad access to adequate health care for all who need it. The root problems underlying health inequity, exposed by COVID‐19, must be addressed, not just to prepare for the next pandemic, but to care for people in resource poor settings in non‐pandemic times. 相似文献
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107.
Laurent Pothuaud Bert Van Rietbergen Cindy Charlot Eugene Ozhinsky 《Computer methods in biomechanics and biomedical engineering》2013,16(4):205-213
Micro-finite element (FE) analysis is a well established technique for the evaluation of the elastic properties of trabecular bone, but is limited in its application due to the large number of elements that it requires to represent the complex internal structure of the bone. In this paper, we present an alternative FE approach that makes use of a recently developed 3D-Line Skeleton Graph Analysis (LSGA) technique to represent the complex internal structure of trabecular bone as a network of simple straight beam elements in which the beams are assigned geometrical properties of the trabeculae that they represent. Since an enormous reduction of cputime can be obtained with this beam modeling approach, ranging from approximately 1,200 to 3,600 for the problems investigated here, we think that the FE modeling technique that we introduced could potentially constitute an interesting alternative for the evaluation of the elastic mechanical properties of trabecular bone. 相似文献
108.
Antioxidant properties of human serum albumin (HSA) may explain part of its beneficial role in various diseases related to free radical attack. In the present study, the antioxidant role of Cys and Met was studied by copper-mediated oxidation of human low density lipoproteins and by free radical-induced blood hemolysis which essentially assessed metal-chelating and free radical scavenging activities, respectively. Mild conditions were set up to specifically modify Cys and Met residues by N-ethylmaleimide (NEM) and chloramine T treatments, respectively. We found that Met and Cys accounted for 40–80% of total antioxidant activity of HSA. Copper binding to HSA was decreased by about 50% with chloramine T treatment of Met whereas no change was observed after NEM treatment of Cys. Although other amino acid residues are likely to be involved in anti-/prooxidant properties of HSA, from our data, we propose that Cys chiefly works as a free radical scavenger whereas Met mainly acts as a metal chelator. 相似文献
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110.
Alexandra Testard Laurent Picot Ingrid Fruitier-Arnaudin Jean-Marie Piot Hadjila Chabane Lisianne Domon 《Journal of enzyme inhibition and medicinal chemistry》2013,28(6):467-473
Novel 6-substituted thiazolocarbazole derivatives have been synthesized under microwave irradiation via the corresponding imino-1,2,3-dithiazoles. In vitro antitumor potential of these polyheterocyclic compounds was evaluated. Among all the tested thiazolocarbazoles, compound 10 is the most effective in inhibiting cell growth. 相似文献