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Abstract: Body size is a common focus of macroevolutionary, macroecological and palaeontological investigations. Here, we document body‐size evolution in 19 species‐level ostracod lineages from the deep Indian Ocean (Deep Sea Drilling Program Site 253) over the past 40 myr. Body‐size trajectories vary across taxa and time intervals, but most lineages (16/19) show net gains in body size. Because many modern ostracod taxa are larger in colder parts of their geographical range, we compared the timing and magnitude of these size changes to established Cenozoic deep‐water cooling patterns confirmed through δ18O measurements of benthic foraminifera in the samples studied. These data show a significant negative correlation between size changes and temperature changes (ostracods get larger as temperatures get colder), and that systematic size increases only occur during intervals of sustained cooling. In addition, statistical support for an explicit temperature‐tracking model exceeds that of purely directional evolution. We argue that this Cope’s Rule pattern is driven by secular changes in the environment, rather than any universal or intrinsic advantages to larger body sizes, and we note some difficulties in the attempts to link Cope’s Rule to observations made within a single generation.  相似文献   

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The physiologic importance of afferent sensory pathways in the esophageal motor functions has been recently recognised. Capsaicin-sensitive sensory afferents were shown to play a role in the maintenance of mucosal integrity of the GI tract, and regulation of human esophageal motility. The aim of this study was to investigate the effect of topical application of capsaicin-containing red pepper sauce (Tabasco, 25%v/v, pH:7.0) suspension on the phasic activity of the human esophagus of healthy volunteers and patients with Barrett’s esophagus. Methods: The diagnosis of Barrett’s esophagus was based on the findings of esophagoscopy and histology taken from the squamocolumnar junction of the esophagus. Esophageal motility was measured by perfusion manometry before and after application of red pepper sauce. Results: Capsaicin containing red pepper sauce increases the motility response (LES tone, contraction amplitude, propagation velocity) of the human esophagus in healthy volunteers. This response failed in patients with Barrett’s esophagus. Conclusion: Impaired esophageal sensorymotor function may serve as one etiologic role in the development of Barrett’s esophagus.  相似文献   

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In this work we present the results of a one‐year study on the macroinvertebrate community in an intermittent stream in southern Spain. We have studied the taxonomic composition, diversity and food web monthly in order to consider temporal variability in these parameters. More than 60 macroinvertebrate taxa have been recorded in the stream, but they do not cohabit at the same time. Many of them join the community at the beginning of the wet period. Afterwards, some new taxa incorporate but some others disappear. This leads to huge fluctuations in the diversity of the community and in the food web of different sampling dates. These variations are linked to environmental disturbances, mainly to flow peaks and minimums. From a relatively well structured, but simple, food web at the beginning of the wet period, it can be seen how several trophic levels disappear with time, and how several organisms change or extend their trophic function within it. We relate these variations to the intermediate disturbance hypothesis and discuss the resilience of the community of this intermittent stream (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

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In concert with improving standards of living since the mid-19th century, chronic and non-infectious diseases replaced infectious diseases as the major causes of mortality in more developed countries. Thus, economic development has been seen as one strategy to improve women's reproductive health. However, rates of two of the major contributors to women's illness, maternal mortality and breast cancer, do not correspond well with the level of economic development. Drawing upon our longitudinal study of reproductive functioning among rural Bolivians (Project Reproduction and Ecology in Provincia Aroma (REPA)), we propose an evolutionary model to explain variation in certain aspects of women's reproductive health. Our findings suggest new avenues of inquiry into the determinants of reproductive health and have implications for improving the well-being of women worldwide.  相似文献   

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The Nahan’s Francolin Francolinus nahani is a globally threatened species associated with remnant forests of the eastern equatorial lowlands of the Democratic Republic of the Congo and Uganda. We studied the species in the Budongo Forest Reserve during March 1998 to January 2000 in an attempt to document some aspects of breeding requirements. We located nests by physically searching the forest and through following radio‐tagged adults. We measured demographical and habitat parameters associated with each nest. Our data suggest that trees of large diameter at breast height with appropriate buttress formation are important for long‐time survival of Nahan’s Francolins.  相似文献   

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Entropy-related biodiversity indices deriving their conceptual basis from Shannon’s information theory have a long history of use in ecology for quantifying community structure and diversity. In addition, in the last two decades, numerous information–theoretical indices, such as the landscape dominance index, have been extensively applied to characterize landscape diversity in space and time. In this contribution, we offer a simple analytical relation between Pielou’s evenness J and landscape dominance D within the broader context of Hill’s parametric diversity family. Within this context, we recommend the use of Hill’s diversity number evenness E1,0 to overcome the shortcomings both of Pielou’s evenness J and the landscape dominance index D.  相似文献   

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Alzheimer's (AD) and Parkinson's diseases (PD) are late-onset neurodegenerative diseases that have tremendous impact on the lives of affected individuals, their families, and society as a whole. Remarkable efforts are being made to elucidate the dominant factors that result in the pathogenesis of these disorders. Extensive postmortem studies suggest that oxidative/nitrative stresses are prominent features of these diseases, and several animal models support this notion. Furthermore, it is likely that protein modifications resulting from oxidative/nitrative damage contribute to the formation of intracytoplasmic inclusions characteristic of each disease. The frequent presentation of both AD and PD in individuals and the co-occurrence of inclusions characteristic of AD and PD in several other neurodegenerative diseases suggests the involvement of a common underlying aberrant process. It can be surmised that oxidative/nitrative stress, which is cooperatively influenced by environmental factors, genetic predisposition, and senescence, may be a link between these disorders.  相似文献   

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The contribution of iron dysregulation to the etiology of a variety of neuronal diseases comes as no surprise given its necessity in numerous general cellular and neuron‐specific functions, its abundance, and its highly reactive nature. Homeostatic mechanisms such as the iron regulatory protein and hypoxia‐inducible factor pathways are firmly evolutionarily set in place to prevent ‘free’ iron from participating in chemical Fenton and Haber‐Weiss reactions which can result in subsequent generation of toxic hydroxyl radicals. However, given the multiple layers of complexity in cellular iron regulation, disruption of any number of genetic and environmental components can disturb the delicate balance between the various molecular players involved in maintaining an appropriate metabolic iron homeostasis. In this review, we will primarily focus on: (i) the impact of aging and gender on iron dysfunction as these are important criteria in the determination of iron‐related disorders such as Parkinson’s disease (PD), (ii) how iron mismanagement via disruption of cellular entry and exit pathways may contribute to these disorders, and (iii) how the availability of non‐invasive measurement of brain iron may aid in PD diagnosis.  相似文献   

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We studied home ranges, habitat use and survival of radio‐tagged Nahan’s Francolin in Budongo Forest Reserve, Uganda during July 1998–December 1999. We studied Nahan’s Francolin in an unlogged nature reserve, in a compartment logged in 1947–1952 and in a compartment logged twice, in 1963–1964 and 1996–1997. Mean home range was 14.22 ± 1.35 ha (n = 17). The home range was significantly larger in the nature reserve than in the recently logged compartment. Birds spent more time during the day in areas with high understorey vegetation density but preferred to roost and nest between buttresses of large trees. Understorey vegetation density and canopy openness were significantly greater in the logged forest than in the nature reserve. Annual survival of adult Nahan’s Francolins was 20.09 ± 7.33% (n = 23). Our results suggest that the maintenance of large trees and areas with high understorey vegetation density are both important for Nahan’s Francolin.  相似文献   

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Antagonists of the human A2A receptor have been reported to have potential therapeutic benefit in the alleviation of the symptoms associated with neurodegenerative movement disorders such as Parkinson’s disease. As part of our efforts to discover potent and selective antagonists of this receptor, we herein describe the detailed optimization and structure–activity relationships of a series of pyrimidine-4-carboxamides. These optimized derivatives display desirable physiochemical and pharmacokinetic profiles, which have led to promising oral activity in clinically relevant models of Parkinson’s disease.  相似文献   

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Autophagy is an evolutionarily conserved homeostatic process for the turnover of cellular contents, organelles and misfolded proteins through the lysosomal machinery. Recently, the involvement of autophagy in the pathophysiology of neurodegenerative diseases has attracted considerable interest because autophagy deregulation has been linked to some of these neurodegenerative disorders. This interest is further heightened by the demonstration that various autophagic pathways, including macroautophagy and chaperone-mediated autophagy, are implicated in the turnover of proteins that are prone to aggregation in cellular or animal disease models. These observations have stimulated new awareness in the pivotal role of the autophagic pathways in neurodegenerative disease pathophysiology, and have sparked extensive research aimed at deciphering the mechanisms by which autophagy is altered in these disorders. Here, we summarize the latest advances in our understanding of the role of autophagy deregulation in Parkinson's, Alzheimer's and Huntington's disease.  相似文献   

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doi: 10.1111/j.1741‐2358.2012.00660.x Periodontitis and Alzheimer’s disease: Oral systemic link still on the rise? Over the past few years, there has been a rapid rise in the older segments of the world population, which has brought along with it a major health concern: dementia. Alzheimer’s disease, considered to be the most common cause of dementia, has become a prospect feared by the elderly. Inflammation of the brain is strongly implicated in Alzheimer’s disease which could be enhanced by systemic inflammation. Periodontitis being a chronic inflammatory condition, which can cause systemic inflammation, the question is whether chronic periodontitis can initiate or hasten the rate of progression of Alzheimer’s disease in susceptible individuals. In this article, the authors outline the proposed oral systemic link between periodontitis and Alzheimer’s disease.  相似文献   

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