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1.
Background
A number of recent papers have cast doubt on the applicability of the quasispecies concept to virus evolution, and have argued that population genetics is a more appropriate framework to describe virus evolution than quasispecies theory. 相似文献2.
Erin Henry Luca Santini Mark A. J. Huijbregts Ana Benítez-López 《Global Ecology and Biogeography》2023,32(2):267-280
Aim
Whether intraspecific spatial patterns in body size are generalizable across species remains contentious, as well as the mechanisms underlying these patterns. Here we test several hypotheses explaining within-species body size variation in terrestrial vertebrates including the heat balance, seasonality, resource availability and water conservation hypotheses for ectotherms, and the heat conservation, heat dissipation, starvation resistance and resource availability hypotheses for endotherms.Location
Global.Time period
1970–2016.Major taxa studied
Amphibians, reptiles, birds and mammals.Methods
We collected 235,905 body size records for 2,229 species (amphibians = 36; reptiles = 81; birds = 1,545; mammals = 567) and performed a phylogenetic meta-analysis of intraspecific correlations between body size and environmental variables. We further tested whether correlations differ between migratory and non-migratory bird and mammal species, and between thermoregulating and thermoconforming ectotherms.Results
For bird species, smaller intraspecific body size was associated with higher mean and maximum temperatures and lower resource seasonality. Size–environment relationships followed a similar pattern in resident and migratory birds, but the effect of resource availability on body size was slightly positive only for non-migratory birds. For mammals, we found that intraspecific body size was smaller with lower resource availability and seasonality, with this pattern being more evident in sedentary than migratory species. No clear size–environment relationships were found for reptiles and amphibians.Main conclusions
Within-species body size variation across endotherms is explained by disparate underlying mechanisms for birds and mammals. Heat conservation (Bergmann's rule) and heat dissipation are the dominant processes explaining biogeographic intraspecific body size variation in birds, whereas in mammals, body size clines are mostly explained by the starvation resistance and resource availability hypotheses. Our findings contribute to a better understanding of the mechanisms behind species adaptations to the environment across their geographic distributions. 相似文献3.
Heather T. Battles 《American journal of physical anthropology》2023,180(3):561-572
Objectives
The traditional polio model depicts a positive relationship between the disease and socioeconomic status (SES), with higher SES associated with exposure to the poliovirus beyond infancy/early childhood and a higher mortality rate. This study uses occupation data from non-Māori New Zealand death registrations and the Census to assess evidence for differential mortality by SES during the polio epidemics of 1916, 1924–25, and 1936–37.Materials and Methods
Polio deaths were classified by father's occupation using the Caversham Project scheme, which includes nine collapsible urban occupational strata and codes rural occupations separately. Evidence for differential mortality and differences in age at death between rural and urban areas and among urban occupational strata was assessed using nonparametric Mann–Whitney U, Kruskal–Wallis, Jonckheere-Terpstra, and chi-square tests.Results
There was limited evidence of either differential mortality or differences in age at death among collapsed urban strata, mainly in 1924/25, only partially meeting the expectations of the traditional polio model. For 1916 only, the rural group had a higher proportion of deaths (χ2 (1, n = 95) = 8.341, p = 0.0039, φ = 0.30)) and higher age at death (U = 828.00, p = 0.026, r = −0.23).Discussion
These results suggest that rural New Zealand was more isolated from poliovirus infection prior to 1916, but thereafter rural and urban groups faced more similar exposure patterns and mortality—at least among non-Māori. The degree to which occupational categories reflect conditions of exposure requires further research.4.
Past vegetation dynamics in the Yellowstone region highlight the vulnerability of mountain systems to climate change
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Virginia Iglesias Cathy Whitlock Teresa R. Krause Richard G. Baker 《Journal of Biogeography》2018,45(8):1768-1780
Aim
Reconstruct the long‐term ecosystem dynamics of the region across an elevational gradient as they relate to climate and local controls. In particular, we (1) describe the dominant conifers' history; (2) assess changes in vegetation composition and distribution; and (3) note periods of abrupt change versus stability as means of better understanding vegetation responses to environmental variability.Location
Greater Yellowstone Ecosystem (GYE; USA).Time period
16.5 ka bp ‐present.Major taxa studied
Juniperus, Picea, Abies, Pinus, Pseudotsuga.Methods
The vegetation reconstruction was developed from 15 pollen records. Results were interpreted based on modern pollen–vegetation relationships estimated from a suite of regression‐based approaches.Results
Calibrated pollen data suggest that late‐glacial vegetation, dominated by shrubs and Juniperus, lacks a modern counterpart in the area. Picea, Abies and Pinus expanded at 16 ka bp in association with postglacial warming and co‐occurred in mixed‐conifer parkland/forest after 12 ka bp . This association along with Pinus contorta forest, which was present after 9 ka bp , has persisted with little change at middle and high elevations to the present day. This stability contrasts with the dynamic history of plant communities at low elevations, where shifts between parkland, steppe and forest over the last 8,000 years were likely driven by variations in effective moisture and fire.Main conclusions
The postglacial vegetation history of the GYE highlights the dynamic nature of mountain ecosystems and informs on their vulnerability to future climate change: (1) most of the conifers have been present in the area for >12,000 years and survived climate change by adjusting their elevational ranges; (2) some plant associations have exhibited stability over millennia as a result of nonclimatic controls; and (3) present‐day forest cover is elevationally more compressed than at any time in history, probably due to the legacy of the Medieval Climate Anomaly and the Little Ice Age. 相似文献5.
Background
Due to recent progress in genome sequencing, more and more data for phylogenetic reconstruction based on rearrangement distances between genomes become available. However, this phylogenetic reconstruction is a very challenging task. For the most simple distance measures (the breakpoint distance and the reversal distance), the problem is NP-hard even if one considers only three genomes. 相似文献6.
Brief report: Lactobacillus bulgaricus GLB44 (Proviotic™) plus esomeprazole for Helicobacter pylori eradication: A pilot study
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Background
Recent studies of Lactobacillus delbrueckii subsp. bulgaricus GLB44 plus a proton‐pump inhibitor (PPI) reported cures of more than 90% of patients with active Helicobacter pylori infections.Aim
To confirm the high H. pylori cure rates reported previously.Method
A pilot study was done in healthy H. pylori‐infected volunteers using 3‐gram sachet (3 billion cells) of L. delbrueckii GLB44 plus 22.3 mg of esomeprazole b.i.d., for 14 days. The result was determined by urea breath testing 4 weeks after therapy. Stopping rules required for ending enrollment if less than 3 of the first 10 subjects were cured.Results
Nine subjects were entered and because all failed to achieve negative urea breath test, the stopping rule required the study to end.Conclusion
We were unable to confirm reports of achieving a high H. pylori cure rate with L. delbrueckii GLB44 plus a PPI. 相似文献7.
Liv Brolund Andrea Küster Sabrina Korr Michael Vogt Gerhard Müller-Newen 《BMC biotechnology》2011,11(1):3
Background
Most cytokines signal through heteromeric receptor complexes consisting of two or more different receptor subunits. Fusion proteins of the extracellular parts of receptor subunits turned out to be promising cytokine inhibitors useful in anti-cytokine therapy and cytokine research. 相似文献8.
Manuela Sironi Giorgia Menozzi Giacomo P Comi Matteo Cereda Rachele Cagliani Nereo Bresolin Uberto Pozzoli 《Genome biology》2007,7(12):R120
Background
Transposable elements (TEs) represent more than 45% of the human and mouse genomes. Both parasitic and mutualistic features have been shown to apply to the host-TE relationship but a comprehensive scenario of the forces driving TE fixation within mammalian genes is still missing. 相似文献9.
Paulo HG Mansur Lacordaire KP Cury José OB Leite Adriano A Pereira Nilson Penha-Silva Adriano O Andrade 《Biomedical engineering online》2010,9(1):29
Background
The main problem of tremor is the damage caused to the quality of the life of patients, especially those at more advanced ages. There is not a consensus yet about the origins of this disorder, but it can be examined in the correlations between the biological signs of aging and the tremor characteristics. 相似文献10.
Background
The objectives of this study were to develop an easy and rapid method for measuring gene expression in a small number of cells by real-time PCR without RNA extraction and purification, and to use this method to determine more precisely IGF-I gene expression in the cumulus cells surrounding oocytes. 相似文献11.
Richard L Summers Steven Platts Jerry G Myers Thomas G Coleman 《Theoretical biology & medical modelling》2010,7(1):8
Background
A tendency to develop reentry orthostasis after a prolonged exposure to microgravity is a common problem among astronauts. The problem is 5 times more prevalent in female astronauts as compared to their male counterparts. The mechanisms responsible for this gender differentiation are poorly understood despite many detailed and complex investigations directed toward an analysis of the physiologic control systems involved. 相似文献12.
Background
Iron deficiency (ID) results in ventricular hypertrophy, believed to involve sympathetic stimulation. We hypothesized that with ID 1) intravenous norepinephrine would alter heart rate (HR) and contractility, 2) abdominal aorta would be larger and more distensible, and 3) the beta-blocker propanolol would reduce hypertrophy. 相似文献13.
A survey of dystocia in the Boxer breed 总被引:1,自引:0,他引:1
Background
Dystocia occurs more commonly in some breeds of dogs than others. The Boxer breed is one of the highrisk breeds for whelping problems. The aim of this study was to document some reproductive parameters and the frequency of dystocia in Boxers. 相似文献14.
Christopher Besemann Anne Denton Nathan J Carr Birgit M Prüβ 《Source code for biology and medicine》2006,1(1):1-13
Background
The large amount of genomics data that have accumulated over the past decade require extensive data mining. However, the global nature of data mining, which includes pattern mining, poses difficulties for users who want to study specific questions in a more local environment. This creates a need for techniques that allow a localized analysis of globally determined patterns. 相似文献15.
Andrea Passerini Claudia Andreini Sauro Menchetti Antonio Rosato Paolo Frasconi 《BMC bioinformatics》2007,8(1):39
Background
Metalloproteins are proteins capable of binding one or more metal ions, which may be required for their biological function, for regulation of their activities or for structural purposes. Metal-binding properties remain difficult to predict as well as to investigate experimentally at the whole-proteome level. Consequently, the current knowledge about metalloproteins is only partial. 相似文献16.
Juan Martinez Warren K. Laskey Cheri Wells Armin Foghi Sarah Rohde Mark Ricciardi Charlotte Mobarak 《Clinical proteomics》2010,6(3):65-73
Introduction
Radiographic contrast media (RCM) have numerous effects on the hemostatic system, inflammatory pathways, and vascular endothelium. Given the increasing number of high-risk patients undergoing radiographic procedures, more information regarding the systemic effects of RCM is needed. 相似文献17.
Background
The primary aim of this study was to obtain more knowledge about the occurrence of Cryptosporidium and Giardia in young dogs in Norway. 相似文献18.
Biotic interactions influence the projected distribution of a specialist mammal under climate change
Brooke L. Bateman Jeremy VanDerWal Stephen E. Williams Christopher N. Johnson 《Diversity & distributions》2012,18(9):861-872
Aim
To measure the effects of including biotic interactions on climate‐based species distribution models (SDMs) used to predict distribution shifts under climate change. We evaluated the performance of distribution models for an endangered marsupial, the northern bettong (Bettongia tropica), comparing models that used only climate variables with models that also took into account biotic interactions.Location
North‐east Queensland, Australia.Methods
We developed separate climate‐based distribution models for the northern bettong, its two main resources and a competitor species. We then constructed models for the northern bettong by including climate suitability estimates for the resources and competitor as additional predictor variables to make climate + resource and climate + resource + competition models. We projected these models onto seven future climate scenarios and compared predictions of northern bettong distribution made by these differently structured models, using a ‘global’ metric, the I similarity statistic, to measure overlap in distribution and a ‘local’ metric to identify where predictions differed significantly.Results
Inclusion of food resource biotic interactions improved model performance. Over moderate climate changes, up to 3.0 °C of warming, the climate‐only model for the northern bettong gave similar predictions of distribution to the more complex models including interactions, with differences only at the margins of predicted distributions. For climate changes beyond 3.0 °C, model predictions diverged significantly. The interactive model predicted less contraction of distribution than the simpler climate‐only model.Main conclusions
Distribution models that account for interactions with other species, in particular direct resources, improve model predictions in the present‐day climate. For larger climate changes, shifts in distribution of interacting species cause predictions of interactive models to diverge from climate‐only models. Incorporating interactions with other species in SDMs may be needed for long‐term prediction of changes in distribution of species under climate change, particularly for specialized species strongly dependent on a small number of biotic interactions. 相似文献19.
Tom Lenaerts Jesper Ferkinghoff-Borg Francois Stricher Luis Serrano Joost WH Schymkowitz Frederic Rousseau 《BMC structural biology》2008,8(1):43
Background
Efficient communication between distant sites within a protein is essential for cooperative biological response. Although often associated with large allosteric movements, more subtle changes in protein dynamics can also induce long-range correlations. However, an appropriate formalism that directly relates protein structural dynamics to information exchange between functional sites is still lacking. 相似文献20.
Yang Li Morris A Swertz Gonzalo Vera Jingyuan Fu Rainer Breitling Ritsert C Jansen 《BMC bioinformatics》2009,10(1):188-7