888 research outputs found
Evolution of sperm morphology in anurans : Insights into the roles of mating system and spawning location
Background: The degree of postcopulatory sexual selection, comprising variable degrees of sperm competition and cryptic female choice, is an important evolutionary
force to influence sperm form and function. Here we investigated the effects of
mating system and spawning location on the evolution of sperm morphology in 67
species of Chinese anurans. We also examined how relative testes mass as an
indicator of the level of sperm competition affected variation in sperm morphology
across a subset of 29 species.
Results: We found a significant association of mating system and spawning location
with sperm morphology. However, when removing the effects of body mass or
absolute testes mass for species for which such data were available, this effect became
non-significant. Consistent with predictions from sperm competition theory, we found
a positive correlation between sperm morphology and relative testes mass after taking
phylogeny into account.
Conclusions: Our findings suggest that sexual selection in Chinese anurans favors
longer sperm when the level of sperm competition is high. Pre-copulatory male-male
competition and spawning location, on the other hand, do not affect the evolution of
sperm morphology after taking body mass and absolute testes mass into account
Geographic variation in life-history traits : growth season affects age structure, egg size and clutch size in Andrew’s toad (Bufo andrewsi)
Background: Environmental variation associated with season length is likely to promote differentiation in lifehistory
traits, but has been little studied in natural populations of ectotherms. We investigated patterns of variation
in egg size, clutch size, age at sexual maturity, maximum age, mean age, growth rate and adult body size in
relation to growth season length among 17 populations of Andrew’s toad (Bufo andrewsi) at different latitudes and
altitudes in the Hengduan Mountains, western China.
Results: We found that egg size, age at sexual maturity, and mean age increased with decreasing length of the
growth season, whereas clutch size showed a converse cline. Body size did not increase with decreasing length of
the growth season, but was tightly linked to lifetime activity (i.e. the estimated number of active days during
lifetime). Males and females differed in their patterns of geographic variation in growth rates, which may be the
result of forces shaping the trade-off between growth and reproduction in different environments.
Conclusions: Our findings suggest that growth season plays an important role in shaping variation in life-history
traits in B. andrewsi across geographical gradients
Sexual size dimorphism in anurans fails to obey Rensch’s rule
Background: Sexual size dimorphism (SSD) is related to ecology, behaviour and life history of organisms. Rensch’s
rule states that SSD increases with overall body size in species where males are the larger sex, while decreasing
with body size when females are larger. To test this rule, we analysed literature as well as own data on male and
female body size in anurans (39 species and 17 genera). We also tested the hypothesis that SSD is largely a
function of age difference between the sexes.
Results: Our data set encompassed 36 species with female-biased SSD, and three species with male-biased SSD. All
considered species failed to support Rensch’s rule, also when the analyses were phylogenetically corrected.
However, SSD was significantly correlated with Sexual Age Difference (SAD) across species. We also found a
significant correlation between SSD contrasts and SAD contrasts.
Conclusions: Our study suggests that Rensch’s rule does not accurately describe macroevolutionary patterns of
SSD in anurans. That SAD can explain most of the variation in SSD among species when controlling for
phylogenetic effects suggests that phylogeny is not responsible for the broad relationship between age and size
across the sexes
Hazard Analysis of Critical Control Points Assessment as a Tool to Respond to Emerging Infectious Disease Outbreaks
Highly pathogenic avian influenza virus (HPAI) strain H5N1 has had direct and indirect economic impacts arising from direct mortality and control programmes in over 50 countries reporting poultry outbreaks. HPAI H5N1 is now reported as the most widespread and expensive zoonotic disease recorded and continues to pose a global health threat. The aim of this research was to assess the potential of utilising Hazard Analysis of Critical Control Points (HACCP) assessments in providing a framework for a rapid response to emerging infectious disease outbreaks. This novel approach applies a scientific process, widely used in food production systems, to assess risks related to a specific emerging health threat within a known zoonotic disease hotspot. We conducted a HACCP assessment for HPAI viruses within Vietnam’s domestic poultry trade and relate our findings to the existing literature. Our HACCP assessment identified poultry flock isolation, transportation, slaughter, preparation and consumption as critical control points for Vietnam’s domestic poultry trade. Introduction of the preventative measures highlighted through this HACCP evaluation would reduce the risks posed by HPAI viruses and pressure on the national economy. We conclude that this HACCP assessment provides compelling evidence for the future potential that HACCP analyses could play in initiating a rapid response to emerging infectious diseases
Behavior and Impact of Zirconium in the Soil–Plant System: Plant Uptake and Phytotoxicity
Because of the large number of sites they pollute, toxic metals that contaminate terrestrial ecosystems are increasingly of environmental and sanitary concern (Uzu et al. 2010, 2011; Shahid et al. 2011a, b, 2012a). Among such metals is zirconium (Zr), which has the atomic number 40 and is a transition metal that resembles titanium in physical and chemical properties (Zaccone et al. 2008). Zr is widely used in many chemical industry processes and in nuclear reactors (Sandoval et al. 2011; Kamal et al. 2011), owing to its useful properties like hardness, corrosion-resistance and permeable to neutrons (Mushtaq 2012). Hence, the recent increased use of Zr by industry, and the occurrence of the Chernobyl and Fukashima catastrophe have enhanced environmental levels in soil and waters (Yirchenko and Agapkina 1993; Mosulishvili et al. 1994 ; Kruglov et al. 1996)
MicroRNAs in pulmonary arterial remodeling
Pulmonary arterial remodeling is a presently irreversible pathologic hallmark of pulmonary arterial hypertension (PAH). This complex disease involves pathogenic dysregulation of all cell types within the small pulmonary arteries contributing to vascular remodeling leading to intimal lesions, resulting in elevated pulmonary vascular resistance and right heart dysfunction. Mutations within the bone morphogenetic protein receptor 2 gene, leading to dysregulated proliferation of pulmonary artery smooth muscle cells, have been identified as being responsible for heritable PAH. Indeed, the disease is characterized by excessive cellular proliferation and resistance to apoptosis of smooth muscle and endothelial cells. Significant gene dysregulation at the transcriptional and signaling level has been identified. MicroRNAs are small non-coding RNA molecules that negatively regulate gene expression and have the ability to target numerous genes, therefore potentially controlling a host of gene regulatory and signaling pathways. The major role of miRNAs in pulmonary arterial remodeling is still relatively unknown although research data is emerging apace. Modulation of miRNAs represents a possible therapeutic target for altering the remodeling phenotype in the pulmonary vasculature. This review will focus on the role of miRNAs in regulating smooth muscle and endothelial cell phenotypes and their influence on pulmonary remodeling in the setting of PAH
Observation of a ppb mass threshoud enhancement in \psi^\prime\to\pi^+\pi^-J/\psi(J/\psi\to\gamma p\bar{p}) decay
The decay channel
is studied using a sample of events collected
by the BESIII experiment at BEPCII. A strong enhancement at threshold is
observed in the invariant mass spectrum. The enhancement can be fit
with an -wave Breit-Wigner resonance function with a resulting peak mass of
and a
narrow width that is at the 90% confidence level.
These results are consistent with published BESII results. These mass and width
values do not match with those of any known meson resonance.Comment: 5 pages, 3 figures, submitted to Chinese Physics
Identification of SNPs in RNA-seq data of two cultivars of Glycine max (soybean) differing in drought resistance
Prevalence and risk factors of abnormal left ventricular geometrical patterns in untreated hypertensive patients
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