共查询到20条相似文献,搜索用时 31 毫秒
1.
Mark V. Lomolino Alexandra A. van der Geer George A. Lyras Maria Rita Palombo Dov F. Sax Roberto Rozzi 《Journal of Biogeography》2013,40(8):1427-1439
Aim
We assessed the generality of the island rule in a database comprising 1593 populations of insular mammals (439 species, including 63 species of fossil mammals), and tested whether observed patterns differed among taxonomic and functional groups.Location
Islands world‐wide.Methods
We measured museum specimens (fossil mammals) and reviewed the literature to compile a database of insular animal body size (Si = mean mass of individuals from an insular population divided by that of individuals from an ancestral or mainland population, M). We used linear regressions to investigate the relationship between Si and M, and ANCOVA to compare trends among taxonomic and functional groups.Results
Si was significantly and negatively related to the mass of the ancestral or mainland population across all mammals and within all orders of extant mammals analysed, and across palaeo‐insular (considered separately) mammals as well. Insular body size was significantly smaller for bats and insectivores than for the other orders studied here, but significantly larger for mammals that utilized aquatic prey than for those restricted to terrestrial prey.Main conclusions
The island rule appears to be a pervasive pattern, exhibited by mammals from a broad range of orders, functional groups and time periods. There remains, however, much scatter about the general trend; this residual variation may be highly informative as it appears consistent with differences among species, islands and environmental characteristics hypothesized to influence body size evolution in general. The more pronounced gigantism and dwarfism of palaeo‐insular mammals, in particular, is consistent with a hypothesis that emphasizes the importance of ecological interactions (time in isolation from mammalian predators and competitors was 0.1 to > 1.0 Myr for palaeo‐insular mammals, but < 0.01 Myr for extant populations of insular mammals). While ecological displacement may be a major force driving diversification in body size in high‐diversity biotas, ecological release in species‐poor biotas often results in the convergence of insular mammals on the size of intermediate but absent species. 相似文献2.
Bernhard Egger Robert Gschwentner Michael W Hess Katharina T Nimeth Zbigniew Adamski Maxime Willems Reinhard Rieger Willi Salvenmoser 《BMC developmental biology》2009,9(1):41-15
Background
Macrostomum lignano is a small free-living flatworm capable of regenerating all body parts posterior of the pharynx and anterior to the brain. We quantified the cellular composition of the caudal-most body region, the tail plate, and investigated regeneration of the tail plate in vivo and in semithin sections labeled with bromodeoxyuridine, a marker for stem cells (neoblasts) in S-phase. 相似文献3.
4.
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5.
Background
The maximum metabolic rate (MMR) of mammals is approximately proportional to M 0.9 , where M is the mammal's body weight. Therefore, MMR increases with body weight faster than does the basal metabolic rate (BMR), which is approximately proportional to M 0.7 . MMR is strongly associated with the capacity of the cardiovascular system to deliver blood to capillaries in the systemic circulation, but properties of this vascular system have not produced an explanation for the scaling of MMR. 相似文献6.
Effect of iron on the expression of sirR and sitABC in biofilm-associated Staphylococcus epidermidis
Caroline Massonet Valerie Pintens Rita Merckx Jozef Anné Elke Lammertyn Johan Van Eldere 《BMC microbiology》2006,6(1):103
Background
Different gene expression patterns correlate with the altered phenotype in biofilm-associated bacteria. Iron and iron-linked genes are thought to play a key-role in biofilm formation. The expression of Fe-linked genes (sirR, sitABC operon) in Staphylococcus epidermidis, was compared in planktonic versus sessile bacteria in vitro and in vivo in a subcutaneous foreign body rat model. 相似文献7.
8.
A meta‐analysis of the association between Helicobacter pylori (H. pylori) infection and hyperemesis gravidarum
下载免费PDF全文
![点击此处可从《Helicobacter》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Qin Xiang Ng Nandini Venkatanarayanan Michelle Lee Zhi Qing De Deyn Collin Yih Xian Ho Yin Mo Wee‐Song Yeo 《Helicobacter》2018,23(1)
Background
Hyperemesis gravidarum remains a common, distressing, and significant yet poorly understood disorder during pregnancy. The association between maternal Helicobacter pylori (H. pylori) infection and hyperemesis gravidarum has been increasingly recognized and investigated. This study thus aimed to provide an updated review and meta‐analysis of the topic.Methods
Using the search terms (H. pyloriOR Helicobacter ORHelicobacter pyloriOR infection) AND (pregnancy OR emesis OR hyperemesis gravidarum OR nausea OR vomiting), a preliminary search on the PubMed, Ovid, Web of Science, Google Scholar, and WanFang database yielded 372 papers published in English between January 1st, 1960 and June 1st, 2017.Results
A total of 38 cross‐sectional and case‐control studies, with a total of 10 289 patients were eligible for review. Meta‐analysis revealed a significant association between H. pylori infection and hyperemesis gravidarum during pregnancy, with a pooled odds ratio of 1.348 (95% CI: 1.156‐1.539, P < .001). Subgroup analysis found that serologic and stool antigen tests were comparable methods of detecting H. pylori as they yielded similar odds ratios.Limitations
Although the studies did not have high heterogeneity (I2 = 28%), publication bias was observed, and interstudy discrepancies in the diagnostic criteria adopted for hyperemesis gravidarum limit the reliability of findings. Also, 15 of the included studies were from the same country (Turkey), which could limit the generalizability of current findings. The prevalence of H. pylori infection varies throughout the world, and there may also be pathogenic differences as most strains of H. pylori in East Asia carry the cytotoxin‐associated gene A gene.Conclusion
H. pylori infection was associated with an increased likelihood of hyperemesis gravidarum during pregnancy. Given the high prevalence of H. pylori infections worldwide, detecting H. pylori infection and the eradication of maternal H. pylori infection could be part of maternal hyperemesis gravidarum management. Further confirmation with robust longitudinal studies and mechanistic investigations are needed. 相似文献9.
Soil moisture effect on bacterial and fungal community in Beilu River (Tibetan Plateau) permafrost soils with different vegetation types 总被引:1,自引:0,他引:1
X.F. Zhang L. Zhao S.J. Xu Jr Y.Z. Liu H.Y. Liu G.D. Cheng 《Journal of applied microbiology》2013,114(4):1054-1065
Aim
This study investigated the effects of environmental variables on the bacterial and fungal communities of the Beilu River (on the Tibetan Plateau) permafrost soils with different vegetation types.Methods and Results
Microbial communities were sampled from meadow, steppe and desert steppe permafrost soils during May, June, August and November, and they were analysed by both pyrosequencing and the use of Biolog EcoPlates. The dominant bacterial and fungal phyla in meadow and steppe soils were Proteobacteria and Ascomycota, whereas Actinobacteria and Basidiomycota predominated in desert steppe soils. The bacterial communities in meadow soils degraded amines and amino acids very rapidly, while polymers were degraded rapidly by steppe communities. The RDA patterns showed that the microbial communities differed greatly between meadow, steppe and desert steppe, and they were related to variations in the soil moisture, C/N ratio and pH. A UniFrac analysis detected clear differences between the desert steppe bacterial community and others, and seasonal shifts were observed. The fungal UniFrac patterns differed significantly between meadow and steppe soils. There were significant correlations between the bacterial diversity (H′) and soil moisture (r = 0·506) and C/N (r = 0·527). The fungal diversity (Hf′) was significantly correlated with the soil pH (r = 0·541).Conclusion
The soil moisture, C/N ratio and pH were important determinants of the microbial community structure in Beilu River permafrost soils.Significance and Impact of the Study
These results may provide a useful baseline for predicting the variation in microbial communities in response to climate changes. 相似文献10.
Cortical beta EEG oscillations related to changes in muscle tone activity during sleep in spider monkey (Ateles geoffroyi)
下载免费PDF全文
![点击此处可从《Journal of medical primatology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Manuel Alejandro Cruz‐Aguilar Miguel Angel Guevara Marisela Hernández‐González Ignacio Ramírez‐Salado Enrique Hernández‐Arteaga Fructuoso Ayala‐Guerrero 《Journal of medical primatology》2018,47(1):67-74
Background
The physiological mechanisms that allow for sleeping in a vertical position, which is primordial for arboreal primates, have not been studied yet.Methods
A non‐invasive polysomnographic study of 6 spider monkeys (Ateles geoffroyi) was conducted. The relative beta power of the motor cortex and its linear relation with muscle tone in the facial mentalis muscle and the abductor caudae medialis muscle of the tail during wakefulness and sleep stages were calculated.Results
A strong negative linear relationship (r = ?.8, P = .03) was found between the relative power of the beta2 band in the left motor cortex and abductor caudae medialis muscle tone during delta sleep.Conclusions
The left motor cortex, through beta2 band activity, interacts with abductor caudae medialis muscle tonicity during delta sleep. This interaction takes part in the mechanisms that regulate the sleep postures. 相似文献11.
Aymé Spor Thibault Nidelet Jonattan Simon Aurélie Bourgais Dominique de Vienne Delphine Sicard 《BMC evolutionary biology》2009,9(1):296
Background
Variation of resource supply is one of the key factors that drive the evolution of life-history strategies, and hence the interactions between individuals. In the yeast Saccharomyces cerevisiae, two life-history strategies related to different resource utilization have been previously described in strains from different industrial origins. In this work, we analyzed metabolic traits and life-history strategies in a broader collection of yeast strains sampled in various ecological niches (forest, human body, fruits, laboratory and industrial environments). 相似文献12.
Lukasz Huminiecki Leon Goldovsky Shiri Freilich Aristidis Moustakas Christos Ouzounis Carl-Henrik Heldin 《BMC evolutionary biology》2009,9(1):28
Background
The question of how genomic processes, such as gene duplication, give rise to co-ordinated organismal properties, such as emergence of new body plans, organs and lifestyles, is of importance in developmental and evolutionary biology. Herein, we focus on the diversification of the transforming growth factor- β (TGF- β) pathway – one of the fundamental and versatile metazoan signal transduction engines. 相似文献13.
Background
The complete genomes of three animals have been sequenced by global research efforts: a nematode worm (Caenorhabditis elegans), an insect (Drosophila melanogaster), and a vertebrate (Homo sapiens). Remarkably, their relationships have yet to be clarified. The confusion concerns the enigmatic position of nematodes. Traditionally, nematodes have occupied a basal position, in part because they lack a true body cavity. However, the leading hypothesis now joins nematodes with arthropods in a molting clade, Ecdysozoa, based on data from several genes. 相似文献14.
Determination of vertebral heart score in three species of Spider monkey (Ateles fusciceps,A. hybridus and A. paniscus)
下载免费PDF全文
![点击此处可从《Journal of medical primatology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Background
The vertebral heart score (VHS) is a method of evaluation of cardiac size well documented in domestic mammals and in other primate species, and the aim of this study was to determine the VHS in three species of Spider monkey.Methods
In this retrospective study, right lateral radiographs of thirty clinically well animals were reviewed and VHS determined. The species included were Ateles fusciceps (n=17), Ateles hybridus (n=8) and Ateles paniscus (n=5).Results
The VHS was found to vary between species and was 9.73±0.81 for A. fusciceps, 10.53±0.37 for A. hybridus and 10.45±0.27 for A. paniscus.Conclusions
The observed values appear consistent with values determined for other primate species. There was statistically significant variation noted between species, and so VHS should be considered species‐specific in this genus. The values determined may be of benefit in objectively evaluating cardiac size in the species investigated. 相似文献15.
16.
Background
The permanently impaired protein folding during recombinant protein production resembles the stress encountered at extreme temperatures, under which condition the putative holding chaperones, IbpA/IbpB, play an important role. We evaluated the impact of ibpAB deletion or overexpression on stress responses and the inclusion body metabolism during production of yeast α-glucosidase in Escherichia coli. 相似文献17.
Borbála Tihanyi Tibor Vellai Ágnes Regős Eszter Ari Fritz Müller Krisztina Takács-Vellai 《BMC developmental biology》2010,10(1):78
Background
Hox genes play a central role in axial patterning during animal development. They are clustered in the genome and specify cell fate in sequential domains along the anteroposterior (A-P) body axis in a conserved order that is co-linear with their relative genomic position. In the soil worm Caenorhabditis elegans, this striking rule of co-linearity is broken by the anterior Hox gene ceh-13, which is located between the two middle Hox paralogs, lin-39 and mab-5, within the loosely organized nematode Hox cluster. Despite its evolutionary and developmental significance, the functional consequence of this unusual genomic organization remains unresolved. 相似文献18.
Evaluation of DNA extraction methods for Bacillus anthracis spores isolated from spiked food samples
M.C. Thomas M.J. Shields K.R. Hahn T.W. Janzen N. Goji K.K. Amoako 《Journal of applied microbiology》2013,115(1):156-162
Aims
Nine commercial DNA extraction kits were evaluated for the isolation of DNA from 10‐fold serial dilutions of Bacillus anthracis spores using quantitative real‐time PCR (qPCR). The three kits determined by qPCR to yield the most sensitive and consistent detection (Epicenter MasterPure Gram Positive; MoBio PowerFood; ABI PrepSeq) were subsequently tested for their ability to isolate DNA from trace amounts of B. anthracis spores (approx. 6·5 × 101 and 1·3 × 102 CFU in 25 ml or 50 g of food sample) spiked into complex food samples including apple juice, ham, whole milk and bagged salad and recovered with immunomagnetic separation (IMS).Methods and Results
The MasterPure kit effectively and consistently isolated DNA from low amounts of B. anthracis spores captured from food samples. Detection was achieved from apple juice, ham, whole milk and bagged salad from as few as 65 ± 14, 68 ± 8, 66 ± 4 and 52 ± 16 CFU, respectively, and IMS samples were demonstrated to be free of PCR inhibitors.Conclusions
Detection of B. anthracis spores isolated from food by IMS differs substantially between commercial DNA extraction kits; however, sensitive results can be obtained with the MasterPure Gram Positive kit.Significance and Impact of the Study
The extraction protocol identified herein combined with IMS is novel for B. anthracis and allows detection of low levels of B. anthracis spores from contaminated food samples. 相似文献19.
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.20.