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991.
Bellwood DR Baird AH Depczynski M González-Cabello A Hoey AS Lefèvre CD Tanner JK 《Oecologia》2012,170(2):567-573
The dynamic nature of coral reefs offers a rare opportunity to examine the response of ecosystems to disruption due to climate change. In 1998, the Great Barrier Reef experienced widespread coral bleaching and mortality. As a result, cryptobenthic fish assemblages underwent a dramatic phase-shift. Thirteen years, and up to 96 fish generations later, the cryptobenthic fish assemblage has not returned to its pre-bleach configuration. This is despite coral abundances returning to, or exceeding, pre-bleach values. The post-bleach fish assemblage exhibits no evidence of recovery. If these short-lived fish species are a model for their longer-lived counterparts, they suggest that (1) the full effects of the 1998 bleaching event on long-lived fish populations have yet to be seen, (2) it may take decades, or more, before recovery or regeneration of these long-lived species will begin, and (3) fish assemblages may not recover to their previous composition despite the return of corals. 相似文献
992.
Ogrzewalska M Saraiva DG Moraes-Filho J Martins TF Costa FB Pinter A Labruna MB 《Parasitology》2012,139(10):1283-1300
SUMMARY The tick-borne bacterium Rickettsia rickettsii is the aetiological agent of Brazilian spotted fever (BSF). The present study evaluated tick infestations on wild and domestic animals, and the rickettsial infection in these animals and their ticks in 7 forest areas adjacent to human communities in the S?o Paulo Metropolitan Area (SPMA). The results were compared to ecological traits of each sampled area. Two main tick species, Amblyomma aureolatum and Rhipicephalus sanguineus, were collected from dogs. The major ticks found on small mammals and birds were Ixodes loricatus and Amblyomma longirostre, respectively. Both anti-R. rickettsii antibodies and R. rickettsii-infected ticks were detected on dogs from only 2 areas in the southern part of the SPMA, which were considered to be endemic for BSF; the remaining 5 areas were considered to be non-endemic. Ecologically, the BSF-endemic areas clearly differed from the non-endemic areas by the presence of significantly more degraded forest patches in the former. The present results corroborate historical observations that have indicated that all human cases of BSF in the SPMA were contracted in the southern part of this metropolitan area. However, not all forest patches in the southern part of the SPMA were shown to be associated with BSF endemism. 相似文献
993.
Satellite sequences are an important part of the pericentromeric regions in mammalian genomes; they play a relevant role in chromosome stability and DNA hypomethylation of these sequences has been reported in ICF syndrome and in some cancers that are closely associated with chromosomal abnormalities. Epigenetic modifications of satellite sequences and their consequences have not been extensively studied in human cells. In the present work, we evaluated satellite 2 methylation patterns in human lymphocytes exposed to 5-azacytidine (5-azaC) and assessed the relationship between these patterns and chromosome missegregation. Human lymphocytes were exposed to 10μM 5-azaC for 24, 48, and 72h. Segregation errors were evaluated in binucleate cells using FISH against pericentromeric regions of chromosomes 1, 9, and 16. DNA methylation patterns were evaluated by immunodetection, and by bisulfite plus urea conversion and sequencing. We have identified that 5-azaC induced missegregation of chromosomes 1 and 16, which have highly methylated satellite 2, after 72h of exposure. Chromosome methylation patterns showed a notable decrease in pericentromeric methylation. Bisulfite conversion and sequencing analysis demonstrated demethylation of satellite 2 associated to 5-azaC exposure, principally after 72h of treatment. This change occurred in a non-specific pattern. Our study demonstrates an association between loss of satellite 2 DNA methylation and chromosome loss in human lymphocytes. 相似文献
994.
González F 《Steroids》2012,77(4):300-305
Chronic low-grade inflammation has emerged as a key contributor to the pathogenesis of Polycystic Ovary Syndrome (PCOS). A dietary trigger such as glucose is capable of inciting oxidative stress and an inflammatory response from mononuclear cells (MNC) of women with PCOS, and this phenomenon is independent of obesity. This is important because MNC-derived macrophages are the primary source of cytokine production in excess adipose tissue, and also promote adipocyte cytokine production in a paracrine fashion. The proinflammatory cytokine tumor necrosis factor-α (TNFα) is a known mediator of insulin resistance. Glucose-stimulated TNFα release from MNC along with molecular markers of inflammation are associated with insulin resistance in PCOS. Hyperandrogenism is capable of activating MNC in the fasting state, thereby increasing MNC sensitivity to glucose; and this may be a potential mechanism for promoting diet-induced inflammation in PCOS. Increased abdominal adiposity is prevalent across all weight classes in PCOS, and this inflamed adipose tissue contributes to the inflammatory load in the disorder. Nevertheless, glucose ingestion incites oxidative stress in normal weight women with PCOS even in the absence of increased abdominal adiposity. In PCOS, markers of oxidative stress and inflammation are highly correlated with circulating androgens. Chronic suppression of ovarian androgen production does not ameliorate inflammation in normal weight women with the disorder. Furthermore, in vitro studies have demonstrated the ability of pro-inflammatory stimuli to upregulate the ovarian theca cell steroidogenic enzyme responsible for androgen production. These findings support the contention that inflammation directly stimulates the polycystic ovary to produce androgens. 相似文献
995.
González-Camacho JM de Los Campos G Pérez P Gianola D Cairns JE Mahuku G Babu R Crossa J 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2012,125(4):759-771
The availability of high density panels of molecular markers has prompted the adoption of genomic selection (GS) methods in animal and plant breeding. In GS, parametric, semi-parametric and non-parametric regressions models are used for predicting quantitative traits. This article shows how to use neural networks with radial basis functions (RBFs) for prediction with dense molecular markers. We illustrate the use of the linear Bayesian LASSO regression model and of two non-linear regression models, reproducing kernel Hilbert spaces (RKHS) regression and radial basis function neural networks (RBFNN) on simulated data and real maize lines genotyped with 55,000 markers and evaluated for several trait-environment combinations. The empirical results of this study indicated that the three models showed similar overall prediction accuracy, with a slight and consistent superiority of RKHS and RBFNN over the additive Bayesian LASSO model. Results from the simulated data indicate that RKHS and RBFNN models captured epistatic effects; however, adding non-signal (redundant) predictors (interaction between markers) can adversely affect the predictive accuracy of the non-linear regression models. 相似文献
996.
Arsuaga JL Fernández Peris J Gracia-Téllez A Quam R Carretero JM Barciela González V Blasco R Cuartero F Sañudo P 《Journal of human evolution》2012,62(5):629-639
Systematic excavations carried out since 1989 at Bolomor Cave have led to the recovery of four Pleistocene human fossil remains, consisting of a fibular fragment, two isolated teeth, and a nearly complete adult parietal bone. All of these specimens date to the late Middle and early Late Pleistocene (MIS 7-5e). The fibular fragment shows thick cortical bone, an archaic feature found in non-modern (i.e. non-Homo sapiens) members of the genus Homo. Among the dental remains, the lack of a midtrigonid crest in the M1 represents a departure from the morphology reported for the majority of Neandertal specimens, while the large dimensions and pronounced shoveling of the marginal ridges in the C1 are similar to other European Middle and late Pleistocene fossils. The parietal bone is very thick, with dimensions that generally fall above Neandertal fossils and resemble more closely the Middle Pleistocene Atapuerca (SH) adult specimens. Based on the presence of archaic features, all the fossils from Bolomor are attributed to the Neandertal evolutionary lineage. 相似文献
997.
Rebelo H Froufe E Brito JC Russo D Cistrone L Ferrand N Jones G 《Molecular ecology》2012,21(11):2761-2774
The barbastelle (Barbastella barbastellus) is a rare forest bat with a wide distribution in Europe. Here, we combine results from the analysis of two mtDNA fragments with species distribution modelling to determine glacial refugia and postglacial colonization routes. We also investigated whether niche conservatism occurs in this species. Glacial refugia were identified in the three southern European peninsulas: Iberia, Italy and the Balkans. These latter two refugia played a major role in the postglacial colonization process, with their populations expanding to England and central Europe, respectively. Palaeo‐distribution models predicted that suitable climatic conditions existed in the inferred refugia during the last glacial maximum (LGM). Nevertheless, the overlap between the current and the LGM distributions was almost inexistent in Italy and in the Balkans, meaning that B. barbastellus populations were forced to shift range between glacial and interglacial periods, a process that probably caused some local extinctions. In contrast, Iberian populations showed a ‘refugia within refugium’ pattern, with two unconnected areas containing stable populations (populations that subsisted during both glacial and interglacial phases). Moreover, the match between LGM models and the refugial areas determined by molecular analysis supported the hypothesis of niche conservatism in B. barbastellus. We argue that geographic patterns of genetic structuring, altogether with the modelling results, indicate the existence of four management units for conservation: Morocco, Iberia, Italy and UK, and Balkans and central Europe. In addition, all countries sampled possessed unique gene pools, thus stressing the need for the conservation of local populations. 相似文献
998.
Burgarella C Navascués M Zabal-Aguirre M Berganzo E Riba M Mayol M Vendramin GG González-Martínez SC 《Molecular ecology》2012,21(12):3006-3021
Taxanes are defensive metabolites produced by Taxus species (yews) and used in anticancer therapies. Despite their medical interest, patterns of natural diversity in taxane-related genes are unknown. We examined variation at five main genes of Taxus baccata in the Iberian Peninsula, a region where unique yew genetic resources are endangered. We looked at several gene features and applied complementary neutrality tests, including diversity/divergence tests, tests solely based on site frequency spectrum (SFS) and Zeng's compound tests. To account for specific demography, microsatellite data were used to infer historical changes in population size based on an Approximate Bayesian Computation (ABC) approach. Polymorphism-divergence tests pointed to positive selection for genes TBT and TAT and balancing selection for DBAT. In addition, neutrality tests based on SFS found that while a recent reduction in population size may explain most statistics' values, selection may still be in action in genes TBT and DBAT, at least in some populations. Molecular signatures on taxol genes suggest the action of frequent selective waves with different direction or intensity, possibly related to varying adaptive pressures produced by the host-enemy co-evolution on defence-related genes. Such natural selection processes may have produced taxane variants still undiscovered. 相似文献
999.
Adela González-Megías Rosa Menéndez 《Philosophical transactions of the Royal Society of London. Series B, Biological sciences》2012,367(1606):3115-3124
Individual species respond to climate change by altering their abundance, distribution and phenology. Less is known, however, about how climate change affects multitrophic interactions, and its consequences for food-web dynamics. Here, we investigate the effect of future changes in rainfall patterns on detritivore–plant–herbivore interactions in a semiarid region in southern Spain by experimentally manipulating rainfall intensity and frequency during late spring–early summer. Our results show that rain intensity changes the effect of below-ground detritivores on both plant traits and above-ground herbivore abundance. Enhanced rain altered the interaction between detritivores and plants affecting flower and fruit production, and also had a direct effect on fruit and seed set. Despite this finding, there was no net effect on plant reproductive output. This finding supports the idea that plants will be less affected by climatic changes than by other trophic levels. Enhanced rain also affected the interaction between detritivores and free-living herbivores. The effect, however, was apparent only for generalist and not for specialist herbivores, demonstrating a differential response to climate change within the same trophic level. The complex responses found in this study suggest that future climate change will affect trophic levels and their interactions differentially, making extrapolation from individual species'' responses and from one ecosystem to another very difficult. 相似文献
1000.
López-Cortés LF Ruiz-Valderas R Jimenez-Jimenez L González-Escribano MF Torres-Cornejo A Mata R Rivero A Pineda JA Marquez-Solero M Viciana P;Grupo para el Estudio de las Hepatitis Víricas 《PloS one》2012,7(1):e28115