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941.
Brett Favaro Danielle C. Claar Caroline H. Fox Cameron Freshwater Jessica J. Holden Allan Roberts UVic Research Derby 《PloS one》2014,9(11)
Protecting and promoting recovery of species at risk of extinction is a critical component of biodiversity conservation. In Canada, the Committee on the Status of Endangered Wildlife in Canada (COSEWIC) determines whether species are at risk of extinction or extirpation, and has conducted these assessments since 1977. We examined trends in COSEWIC assessments to identify whether at-risk species that have been assessed more than once tended to improve, remain constant, or deteriorate in status, as a way of assessing the effectiveness of biodiversity conservation in Canada. Of 369 species that met our criteria for examination, 115 deteriorated, 202 remained unchanged, and 52 improved in status. Only 20 species (5.4%) improved to the point where they were ‘not at risk’, and five of those were due to increased sampling efforts rather than an increase in population size. Species outcomes were also dependent on the severity of their initial assessment; for example, 47% of species that were initially listed as special concern deteriorated between assessments. After receiving an at-risk assessment by COSEWIC, a species is considered for listing under the federal Species at Risk Act (SARA), which is the primary national tool that mandates protection for at-risk species. We examined whether SARA-listing was associated with improved COSEWIC assessment outcomes relative to unlisted species. Of 305 species that had multiple assessments and were SARA-listed, 221 were listed at a level that required identification and protection of critical habitat; however, critical habitat was fully identified for only 56 of these species. We suggest that the Canadian government should formally identify and protect critical habitat, as is required by existing legislation. In addition, our finding that at-risk species in Canada rarely recover leads us to recommend that every effort be made to actively prevent species from becoming at-risk in the first place. 相似文献
942.
Allison B Herman Carlos Anerillas Sophia C Harris Rachel Munk Jennifer
L Martindale Xiaoling Yang Krystyna Mazan-Mamczarz Yongqing Zhang Indra
J Heckenbach Morten Scheibye-Knudsen Supriyo De Payel Sen Kotb Abdelmohsen Myriam Gorospe 《Nucleic acids research》2021,49(13):7389
A major stress response influenced by microRNAs (miRNAs) is senescence, a state of indefinite growth arrest triggered by sublethal cell damage. Here, through bioinformatic analysis and experimental validation, we identified miR-340-5p as a novel miRNA that foments cellular senescence. miR-340-5p was highly abundant in diverse senescence models, and miR-340-5p overexpression in proliferating cells rendered them senescent. Among the target mRNAs, miR-340-5p prominently reduced the levels of LBR mRNA, encoding lamin B receptor (LBR). Loss of LBR by ectopic overexpression of miR-340-5p derepressed heterochromatin in lamina-associated domains, promoting the expression of DNA repetitive elements characteristic of senescence. Importantly, overexpressing miR-340-5p enhanced cellular sensitivity to senolytic compounds, while antagonization of miR-340-5p reduced senescent cell markers and engendered resistance to senolytic-induced cell death. We propose that miR-340-5p can be exploited for removing senescent cells to restore tissue homeostasis and mitigate damage by senescent cells in pathologies of human aging. 相似文献
943.
Arielle M. Cooley Suzanne Schmitz Eduardo J. Cabrera Mitchell Cutter Maxwell Sheffield Ian Gingerich Gabriella Thomas Calvin N. M. Lincoln Virginia H. Moore Alexandra E. Moore Sarah A. Davidson Nikhil Lonberg Eli B. Fournier Sophia M. Love Galen Posch Matthew B. Bihrle Spencer D. Mayer Kuenzang Om Lauren Wilson Casey Q. Doe Chantalle E. Vincent Elizabeth R. T. Wong Ilona Wall Jarred Wicks Stephon Roberts 《Ecology and evolution》2021,11(18):12542
Environmental adaptation and species divergence often involve suites of co‐evolving traits. Pigmentation in insects presents a variable, adaptive, and well‐characterized class of phenotypes for which correlations with multiple other traits have been demonstrated. In Drosophila, the pigmentation genes ebony and tan have pleiotropic effects on flies'' response to light, creating the potential for correlated evolution of pigmentation and vision. Here, we investigate differences in light preference within and between two sister species, Drosophila americana and D. novamexicana, which differ in pigmentation in part because of evolution at ebony and tan and occupy environments that differ in many variables including solar radiation. We hypothesized that lighter pigmentation would be correlated with a greater preference for environmental light and tested this hypothesis using a habitat choice experiment. In a first set of experiments, using males of D. novamexicana line N14 and D. americana line A00, the light‐bodied D. novamexicana was found slightly but significantly more often than D. americana in the light habitat. A second experiment, which included additional lines and females as well as males, failed to find any significant difference between D. novamexicana‐N14 and D. americana‐A00. Additionally, the other dark line of D. americana (A04) was found in the light habitat more often than the light‐bodied D. novamexicana‐N14, in contrast to our predictions. However, the lightest line of D. americana, A01, was found substantially and significantly more often in the light habitat than the two darker lines of D. americana, thus providing partial support for our hypothesis. Finally, across all four lines, females were found more often in the light habitat than their more darkly pigmented male counterparts. Additional replication is needed to corroborate these findings and evaluate conflicting results, with the consistent effect of sex within and between species providing an especially intriguing avenue for further research. 相似文献
944.
Sebastian Steibl Robert Sigl Sanja Blaha Sophia Drescher Gerhard Gebauer Elif Gürkal Frederic Hüftlein Anna Satzger Michael Schwarzer Dimitri Seidenath Jana Welfenbach Raphael S. Zinser Christian Laforsch 《Ecology and evolution》2021,11(19):13128
Ecosystems are interconnected by energy fluxes that provide resources for the inhabiting organisms along the transition zone. Especially where in situ resources are scarce, ecosystems can become highly dependent on external resources. The dependency on external input becomes less pronounced in systems with elevated in situ production, where only consumer species close to the site of external input remain subsidized, whereas species distant to the input site rely on the in situ production of the ecosystem. It is largely unclear though if this pattern is consistent over different consumer species and trophic levels in one ecosystem, and whether consumer species that occur both proximate to and at a distance from the input site differ in their dependency on external resource inputs between sites. Using stable isotope analysis, we investigated the dependency on external marine input for common ground‐associated consumer taxa on small tropical islands with high in situ production. We show that marine input is only relevant for strict beach‐dwelling taxa, while the terrestrial vegetation is the main carbon source for inland‐dwelling taxa. Consumer species that occurred both close (beach) and distant (inland) to the site of marine input showed similar proportions of marine input in their diets. This supports earlier findings that the relevance of external resources becomes limited to species close to the input site in systems with sufficient in situ production. However, it also indicates that the relevance of external input is also species‐dependent, as consumers occurring close and distant to the input site depended equally strong or weak on marine input. 相似文献
945.
Tail autotomy is a defense against predators used by many lizard species but is associated with various costs, most of which
have been measured only in the laboratory. We conducted a field experiment in which we induced tail autotomy to approximately
half (58%) of a marked sample (n=326) of Uta stansburiana from western Texas in the fall, and left the other half with intact tails. The following spring we determined survival, measured
growth, and brought females to the laboratory to allow them to oviposit their eggs, which we incubated until hatching. Based
on past studies, we anticipated inferior survival, growth, and reproduction following tail autotomy. We also predicted that
females with tail loss would be energetically compromised and would alter the sex ratio of their offspring toward more daughters
(as predicted by the Trivers-Willard hypothesis). Tailless lizards experienced significantly reduced survivorship, but those
that survived grew the same as their tailed counterparts. Tailed and tailless females produced clutches equivalent in number
of eggs and total mass. Whereas tailed females showed a significant positive relationship between average egg mass and snout-vent
length, tailless females did not. Contrary to our expectations, tailless females produced heavier hatchlings than tailed ones,
and sex ratios of hatchlings were equivalent for tailed and tailless females. In this population, tail loss in subadults leads
to an increased risk of death, but apparently does not impose an energetic handicap such that later growth and reproduction
suffer. We suggest that because tailless females are faced with decreased reproductive value, they respond by growing as much
and laying as many eggs of the same mass as tailed females, despite the fact that they are also regenerating the tail. In
addition, they somehow produce larger hatchlings than tailed females. Nevertheless, tailless females probably end up with
lower overall lifetime fitness than tailed females, and tail loss thus induces the conditional reproductive strategy ”make
the best of a bad situation”. Because tailless females produce larger, not smaller, hatchlings, they do not produce more daughters
as predicted; i.e., we found no evidence for the Trivers-Willard effect following tail autotomy.
Received: 29 November 1998 / Accepted: 17 September 1999 相似文献
946.
Gamma-aminobutyric acid type A (GABAA) receptors in brain adapt to chronic ethanol exposure via changes in receptor function and subunit expression. The present review summarizes currently available data regarding changes in GABAA receptor subunit mRNA and peptide expression. Data are presented from various different brain regions and the variations between specific brain regions used to draw conclusions about mechanisms that may underlie GABAA receptor adaptations during chronic ethanol exposure. In the whole cerebral cortex, chronic ethanol exposure leads to a reduction of GABAA receptor α1 subunit mRNA and peptide levels and a near equivalent increase in α4 subunit mRNA and peptide levels. This observation is the primary support for the hypothesis that altered receptor composition is a mechanism for GABAA receptor adaptation produced by chronic ethanol exposure. However, other brain regions do not display similar patterns of subunit changes. Moreover, subregions within cortex (prefrontal, cingulate, parietal, motor, and piriform) exhibit patterns of changes in subunit expression that differ from whole cortex. Therefore, regional differences in GABAA receptor subunit expression are evident following chronic ethanol administration, thus suggesting that multiple mechanisms contribute to the regulation of GABAA receptor expression. These mechanisms may include the involvement of other neurotransmitter systems, endogenous steroids and second or third messenger cross-talk. 相似文献
947.
Transformation of 2,4,6-Trinitrotoluene by Purified Xenobiotic Reductase B from Pseudomonas fluorescens I-C 总被引:2,自引:0,他引:2 下载免费PDF全文
Jeong W. Pak Kyle L. Knoke Daniel R. Noguera Brian G. Fox Glenn H. Chambliss 《Applied microbiology》2000,66(11):4742-4750
The enzymatic transformation of 2,4,6-trinitrotoluene (TNT) by purified XenB, an NADPH-dependent flavoprotein oxidoreductase from Pseudomonas fluorescens I-C, was evaluated by using natural abundance and [U-14C]TNT preparations. XenB catalyzed the reduction of TNT either by hydride addition to the aromatic ring or by nitro group reduction, with the accumulation of various tautomers of the protonated dihydride-Meisenheimer complex of TNT, 2-hydroxylamino-4,6-dinitrotoluene, and 4-hydroxylamino-2,6-dinitrotoluene. Subsequent reactions of these metabolites were nonenzymatic and resulted in predominant formation of at least three dimers with an anionic m/z of 376 as determined by negative-mode electrospray ionization mass spectrometry and the release of ~0.5 mol of nitrite per mol of TNT consumed. The extents of the initial enzymatic reactions were similar in the presence and in the absence of O2, but the dimerization reaction and the release of nitrite were favored under aerobic conditions or under anaerobic conditions in the presence of NADP+. Reactions of chemically and enzymatically synthesized and high-pressure liquid chromatography-purified TNT metabolites showed that both a hydroxylamino-dinitrotoluene isomer and a tautomer of the protonated dihydride-Meisenheimer complex of TNT were required precursors for the dimerization and nitrite release reactions. The m/z 376 dimers also reacted with either dansyl chloride or N-1-naphthylethylenediamine HCl, providing evidence for an aryl amine functional group. In combination, the experimental results are consistent with assigning the chemical structures of the m/z 376 species to various isomers of amino-dimethyl-tetranitrobiphenyl. A mechanism for the formation of these proposed TNT metabolites is presented, and the potential enzymatic and environmental significance of their formation is discussed. 相似文献
948.
Samantha Swank Ethan Elazegui Sophia Janidlo Thomas J. Sanger Michael A. Bell Yoel E. Stuart 《Ecology and evolution》2022,12(7)
Loss and reduction in paired appendages are common in vertebrate evolution. How often does such convergent evolution depend on similar developmental and genetic pathways? For example, many populations of the threespine stickleback and ninespine stickleback (Gasterosteidae) have independently evolved pelvic reduction, usually based on independent mutations that caused reduced Pitx1 expression. Reduced Pitx1 expression has also been implicated in pelvic reduction in manatees. Thus, hindlimb reduction stemming from reduced Pitx1 expression has arisen independently in groups that diverged tens to hundreds of millions of years ago, suggesting a potential for repeated use of Pitx1 across vertebrates. Notably, hindlimb reduction based on the reduction in Pitx1 expression produces left‐larger directional asymmetry in the vestiges. We used this phenotypic signature as a genetic proxy, testing for hindlimb directional asymmetry in six genera of squamate reptiles that independently evolved hindlimb reduction and for which genetic and developmental tools are not yet developed: Agamodon anguliceps, Bachia intermedia, Chalcides sepsoides, Indotyphlops braminus, Ophisaurus attenuatuas and O. ventralis, and Teius teyou. Significant asymmetry occurred in one taxon, Chalcides sepsoides, whose left‐side pelvis and femur vestiges were 18% and 64% larger than right‐side vestiges, respectively, suggesting modification in Pitx1 expression in that species. However, there was either right‐larger asymmetry or no directional asymmetry in the other five taxa, suggesting multiple developmental genetic pathways to hindlimb reduction in squamates and the vertebrates more generally. 相似文献
949.
Solomon A. Sloat Luke M. Noble Annalise B. Paaby Max Bernstein Audrey Chang Taniya Kaur John Yuen Sophia C. Tintori Jacqueline L. Jackson Arielle Martel Jose A. Salome Correa Lewis Stevens Karin Kiontke Mark Blaxter Matthew V. Rockman 《Ecology and evolution》2022,12(7)
Factors shaping the distribution and abundance of species include life‐history traits, population structure, and stochastic colonization–extinction dynamics. Field studies of model species groups help reveal the roles of these factors. Species of Caenorhabditis nematodes are highly divergent at the sequence level but exhibit highly conserved morphology, and many of these species live in sympatry on microbe‐rich patches of rotten material. Here, we use field experiments and large‐scale opportunistic collections to investigate species composition, abundance, and colonization efficiency of Caenorhabditis species in two of the world''s best‐studied lowland tropical field sites: Barro Colorado Island in Panamá and La Selva in Sarapiquí, Costa Rica. We observed seven species of Caenorhabditis, four of them known only from these collections. We formally describe two species and place them within the Caenorhabditis phylogeny. While these localities contain species from many parts of the phylogeny, both localities were dominated by globally distributed androdiecious species. We found that Caenorhabditis individuals were able to colonize baits accessible only through phoresy and preferentially colonized baits that were in direct contact with the ground. We estimate the number of colonization events per patch to be low. 相似文献
950.
Ramona Moles Sarkis Sarkis Veronica Galli Maria Omsland Maria Artesi Massimiliano Bissa Katherine McKinnon Sophia Brown Vincent Hahaut Robyn Washington-Parks Joshua Welsh David J. Venzon Anna Gutowska Melvin N. Doster Matthew W. Breed Kristin E. Killoran Joshua Kramer Jennifer Jones Marcin Moniuszko Anne Van den Broeke Cynthia A. Pise-Masison Genoveffa Franchini 《PLoS pathogens》2022,18(4)
We investigated the impact of monocytes, NK cells, and CD8+ T-cells in primary HTLV-1 infection by depleting cell subsets and exposing macaques to either HTLV-1 wild type (HTLV-1WT) or to the HTLV-1p12KO mutant unable to infect replete animals due to a single point mutation in orf-I that inhibits its expression. The orf-I encoded p8/p12 proteins counteract cytotoxic NK and CD8+ T-cells and favor viral DNA persistence in monocytes. Double NK and CD8+ T-cells or CD8 depletion alone accelerated seroconversion in all animals exposed to HTLV-1WT. In contrast, HTLV-1p12KO infectivity was fully restored only when NK cells were also depleted, demonstrating a critical role of NK cells in primary infection. Monocyte/macrophage depletion resulted in accelerated seroconversion in all animals exposed to HTLV-1WT, but antibody titers to the virus were low and not sustained. Seroconversion did not occur in most animals exposed to HTLV-1p12KO. In vitro experiments in human primary monocytes or THP-1 cells comparing HTLV-1WT and HTLV-1p12KO demonstrated that orf-I expression is associated with inhibition of inflammasome activation in primary cells, with increased CD47 “don’t-eat-me” signal surface expression in virus infected cells and decreased monocyte engulfment of infected cells. Collectively, our data demonstrate a critical role for innate NK cells in primary infection and suggest a dual role of monocytes in primary infection. On one hand, orf-I expression increases the chances of viral transmission by sparing infected cells from efferocytosis, and on the other may protect the engulfed infected cells by modulating inflammasome activation. These data also suggest that, once infection is established, the stoichiometry of orf-I expression may contribute to the chronic inflammation observed in HTLV-1 infection by modulating monocyte efferocytosis. 相似文献