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961.
Guillermo López Marcos López-Parra Germán Garrote Leonardo Fernández Teresa del Rey-Wamba Rafael Arenas-Rojas Maribel García-Tardío Gema Ruiz Irene Zorrilla Manuel Moral Miguel A. Simón 《European Journal of Wildlife Research》2014,60(2):359-366
The conservation of endangered species requires accurate data, and knowledge of cause-specific mortality rates is one of the most important issues. In recent years, conservation programs for the critically endangered Iberian lynx Lynx pardinus have been developed on the basis of mortality data derived 30 years ago from the small Doñana population. Thus, there is an urgent need for an update of mortality rates and causes in both populations (Sierra Morena and Doñana). Here we use radio-tracking information from the whole range of the Iberian lynx to quantify mortality rates and identify their causes. Between 2006 and 2011, we radio-tagged 78 Iberian lynxes from its two remaining populations (39 from Sierra Morena and 39 from Doñana). Mortality events were evaluated to identify causes, and cause-specific annual mortality rates (AMR) were obtained using the nonparametric cumulative incidence function estimator. Overall, AMR was estimated at 0.16?±?0.05 (0.19?±?0.09 in Sierra Morena and 0.12?±?0.07 in Doñana). Disease was the main cause of mortality both for the whole population and the Doñana population. Poaching was the main cause of mortality in Sierra Morena. Our results suggest that the best strategy for conserving this species is to focus action on decreasing the fatal effect of disease and poaching. Given the possible existence of an underlying inbreeding-mediated immunosuppression, genetic management aimed at increasing the genetic diversity of this population is also recommended. 相似文献
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963.
Andrés Andrade-Domínguez Emmanuel Salazar María del Carmen Vargas-Lagunas Roberto Kolter Sergio Encarnación 《The ISME journal》2014,8(5):1041-1054
In the biosphere, many species live in close proximity and can thus interact in many different ways. Such interactions are dynamic and fall along a continuum between antagonism and cooperation. Because interspecies interactions are the key to understanding biological communities, it is important to know how species interactions arise and evolve. Here, we show that the feedback between ecological and evolutionary processes has a fundamental role in the emergence and dynamics of species interaction. Using a two-species artificial community, we demonstrate that ecological processes and rapid evolution interact to influence the dynamics of the symbiosis between a eukaryote (Saccharomyces cerevisiae) and a bacterium (Rhizobium etli). The simplicity of our experimental design enables an explicit statement of causality. The niche-constructing activities of the fungus were the key ecological process: it allowed the establishment of a commensal relationship that switched to ammensalism and provided the selective conditions necessary for the adaptive evolution of the bacteria. In this latter state, the bacterial population radiates into more than five genotypes that vary with respect to nutrient transport, metabolic strategies and global regulation. Evolutionary diversification of the bacterial populations has strong effects on the community; the nature of interaction subsequently switches from ammensalism to antagonism where bacteria promote yeast extinction. Our results demonstrate the importance of the evolution-to-ecology pathway in the persistence of interactions and the stability of communities. Thus, eco-evolutionary dynamics have the potential to transform the structure and functioning of ecosystems. Our results suggest that these dynamics should be considered to improve our understanding of beneficial and detrimental host–microbe interactions. 相似文献
964.
Michael A. Tabak Sally Poncet Ken Passfield Carlos Martinez del Rio 《Biological invasions》2014,16(2):341-352
Invasive species pose significant threats to biodiversity, especially on islands. They cause extinctions and population declines, yet little is known about their consequences on the emergent, metacommunity-level patterns of native species in island assemblages. We investigated differences in species–area relationships, nestedness, and occupancy of 9 species of native land birds between island assemblages with and without invasive Norway rats (Rattus norvegicus) in the Falkland Archipelago. We found that species–area curves, nestedness, and individual species’ occurrences differed between island assemblages with and without rats. Rat-free islands had, on average, 2.1 more land bird species than rat-infested islands of similar size. Passerine bird communities on islands with and without rats were significantly nested, but nestedness was significantly higher on rat-free islands than on rat-infested islands. The presence of rats was associated with differences in the incidence of many, but not all bird species. On rat free islands the occurrence of all species increased with island area. The occurrence of most, albeit not all, bird species was lower on islands with than on islands without rats. Two species of conservation concern, Troglodytes aedon cobbi and Cinclodes antarcticus, were abundant on rat-free islands, but absent or found at very low frequencies on islands with rats. The occurrence of three species was not associated with the presence of rats. The patterns presented here can be used to evaluate the consequences of ongoing rat eradications for passerine diversity, distribution, and abundance. 相似文献
965.
Terence A. Agbor Zachary Demma Randall J. Mrsny Antonio Castillo Erik J. Boll Beth A. McCormick 《Cellular microbiology》2014,16(9):1339-1353
Neutrophil (polymorphonuclear leucocytes; PMN) transmigration across mucosal surfaces contributes to dysfunction of epithelial barrier properties, a characteristic underlying many mucosal inflammatory diseases. Using Salmonella enterica serovar Typhimurium (S. Typhimurium) as a prototypic proinflammatory insult, we have previously reported that the eicosanoid hepoxilin A3 (HXA3), an endogenous product of 12‐lipoxygenase (12‐LOX) activity, is secreted from the apical surface of the intestinal epithelium to establish a chemotactic gradient that guides PMN across the epithelial surface. Since little is known regarding the molecular mechanisms that regulate 12‐LOX during S. Typhimurium infection, we investigated this pathway. We found that expression of phospholipid glutathione peroxidase (GPX4), which is known to have an inhibitory effect on 12‐LOX activity, is significantly decreased at both the mRNA and protein level during infection with S. Typhimurium. Moreover, employing intestinal epithelial cell monolayers expressing siRNA against GPX4 mRNA, S. Typhimurium‐induced PMN migration was significantly increased compared with the non‐specific siRNA control cells. Conversely, in cells engineered to overexpress GPX4, S. Typhimurium‐induced PMN migration was significantly decreased, which is consistent with the finding that partial depletion of GPX4 by RNAi resulted in a significant increase in HXA3 secretion during S. Typhimurium infection. Mechanistically, although we found Salmonella entry not to be required for the induced decrease in GPX4, the secreted effector, SipA, which is known to induce epithelial responses leading to stimulation of HXA3, governed the decrease in GPX4 in a process that does not lead to an overall increase in the levels of ROS. Taken together, these results suggest that S. Typhimurium induces apical secretion of HXA3 by decreasing the expression of phospholipid GPX, which in turn leads to an increase in 12‐LOX activity, and hence HXA3 synthesis. 相似文献
966.
Elective abortion has become an issue of ethical and political debate in many countries including Mexico. As gynecologists are directly involved in the practice of abortion, it is important to know the psychological meaning that the term ‘elective abortion’ has for them. This study explores the psychological meaning and attitudes toward elective abortion of one hundred and twenty‐three Mexican gynecologists. We used the semantic networks technique, which analyzed the words the participants associated with the term ‘elective abortion’. The defining words most frequently used by participants implied a negative sanction. There were important differences by gender and religiosity: male gynecologists, as well as those with strong religious beliefs (mainly Catholics), revealed a more negative psychological meaning and more negative attitudes than females or physicians with weak religious beliefs. A contribution of the present study is that it highlights the importance of psychology to enhancing understanding of the issue of elective abortion. 相似文献
967.
C. D. Kenkel C. Sheridan M. C. Leal R. Bhagooli K. D. Castillo N. Kurata E. McGinty T. L. Goulet M. V. Matz 《Molecular ecology resources》2014,14(4):667-678
Gene expression biomarkers can enable rapid assessment of physiological conditions in situ, providing a valuable tool for reef managers interested in linking organism physiology with large‐scale climatic conditions. Here, we assessed the ability of quantitative PCR (qPCR)‐based gene expression biomarkers to evaluate (i) the immediate cellular stress response (CSR) of Porites astreoides to incremental thermal stress and (ii) the magnitude of CSR and cellular homeostasis response (CHR) during a natural bleaching event. Expression levels largely scaled with treatment temperature, with the strongest responses occurring in heat‐shock proteins. This is the first demonstration of a ‘tiered’ CSR in a coral, where the magnitude of expression change is proportional to stress intensity. Analysis of a natural bleaching event revealed no signature of an acute CSR in normal or bleached corals, indicating that the bleaching stressor(s) had abated by the day of sampling. Another long‐term stress CHR‐based indicator assay was significantly elevated in bleached corals, although assay values overall were low, suggesting good prospects for recovery. This study represents the first step in linking variation in gene expression biomarkers to stress tolerance and bleaching thresholds in situ by quantifying the severity of ongoing thermal stress and its accumulated long‐term impacts. 相似文献
968.
969.
970.
Jesús García-López Juan de Dios Hourcade Lola Alonso David B. Cárdenas Jesús del Mazo 《Biochimica et Biophysica Acta (BBA) - Gene Regulatory Mechanisms》2014,1839(6):463-475
A set of small RNAs known as rasRNAs (repeat-associated small RNAs) have been related to the down-regulation of Transposable Elements (TEs) to safeguard genome integrity. Two key members of the rasRNAs group are piRNAs and endo-siRNAs. We have performed a comparative analysis of piRNAs and endo-siRNAs present in mouse oocytes, spermatozoa and zygotes, identified by deep sequencing and bioinformatic analysis. The detection of piRNAs and endo-siRNAs in the spermatozoa and revealed also in zygotes, hints to their potential delivery to oocytes during fertilization. However, a comparative assessment of the three cell types indicates that both piRNAs and endo-siRNAs are mainly maternally inherited. Finally, we have assessed the role of the different rasRNA molecules in connection with amplification processes by way of the “ping-pong cycle”. Our results suggest that the ping-pong cycle can act on other rasRNAs, such as tRNA- and rRNA-derived fragments, thus not only being restricted to TEs during gametogenesis. 相似文献