中国西北沙漠夜间活动的东鳖甲属昆虫二新种(鞘翅目:拟步甲科:漠甲亚科)

记述中国西北地区东鳖甲属2新种:巴丹东鳖甲A.badainica Ba,Ren&Liu sp.nov.和古尔班东鳖甲A.gurbantunggutica Ba&Ren sp.nov.,提供了主要鉴别特征和形态图,并简要讨论了其昼夜活动规律.     

Haemosporidian Parasites of Antelopes and Other Vertebrates from Gabon,Central Africa

Re-examination, using molecular tools, of the diversity of haemosporidian parasites (among which the agents of human malaria are the best known) has generally led to rearrangements of traditional classifications. In this study, we explored the diversity of haemosporidian parasites infecting vertebrate species (particularly mammals, birds and reptiles) living in the forests of Gabon (Central Africa), by analyzing a collection of 492 bushmeat samples. We found that samples from five mammalian species (four duiker and one pangolin species), one bird and one turtle species were infected by haemosporidian parasites. In duikers (from which most of the infected specimens were obtained), we demonstrated the existence of at least two distinct parasite lineages related to Polychromophilus species (i.e., bat haemosporidian parasites) and to sauropsid Plasmodium (from birds and lizards). Molecular screening of sylvatic mosquitoes captured during a longitudinal survey revealed the presence of these haemosporidian parasite lineages also in several Anopheles species, suggesting a potential role in their transmission. Our results show that, differently from what was previously thought, several independent clades of haemosporidian parasites (family Plasmodiidae) infect mammals and are transmitted by anopheline mosquitoes.     

Molecular basis of ion permeability in a voltage‐gated sodium channel

Voltage‐gated sodium channels are essential for electrical signalling across cell membranes. They exhibit strong selectivities for sodium ions over other cations, enabling the finely tuned cascade of events associated with action potentials. This paper describes the ion permeability characteristics and the crystal structure of a prokaryotic sodium channel, showing for the first time the detailed locations of sodium ions in the selectivity filter of a sodium channel. Electrostatic calculations based on the structure are consistent with the relative cation permeability ratios (Na⁺ ≈ Li⁺ ≫ K⁺, Ca²⁺, Mg²⁺) measured for these channels. In an E178D selectivity filter mutant constructed to have altered ion selectivities, the sodium ion binding site nearest the extracellular side is missing. Unlike potassium ions in potassium channels, the sodium ions in these channels appear to be hydrated and are associated with side chains of the selectivity filter residues, rather than polypeptide backbones.     

Efficacy of hyaluronic acid binding assay in selecting motile spermatozoa with normal morphology at high magnification

Background  

The present study aimed to evaluate the efficacy of the hyaluronic acid (HA) binding assay in the selection of motile spermatozoa with normal morphology at high magnification (8400x).     

Characterization of mesophilic bacilli in faeces of feedlot cattle

AIMS: To determine the identity and composition of mesophilic Bacillus spp. in faeces sampled from feedlot cattle. METHODS AND RESULTS: Faecal samples from 10 feedlot cattle were analysed. The total aerobic spore count increased from 4.6 x 10(4) CFU g(-1) (before feedlotting, day 0) to 1.6 x 10(6) CFU g(-1) (feedlot for day 76). A total of 150 randomly selected spore isolates (60 each from days 0 and 76 cattle, 30 from feed) were speciated using a Bacillus group-specific PCR-amplified ribosomal DNA restriction analysis technique (Wu et al. 2006). At day 0, Bacillus subtilis and Bacillus cereus predominated with a prevalence of 58.3% and 26.7%, respectively, whereas three species, B. subtilis (50.0%), Bacillus licheniformis (27.6%) and Bacillus clausii (20.0%) predominated in day 76 faecal samples. Of these, only the first two species were present in feed samples at a frequency of 70% and 30% respectively. All B. cereus isolates on day 0, possessed at least one of three enterotoxin genes (nheA, nheB and nheC) but these were completely eliminated after a period of feedlotting. All isolates of B. licheniformis were genotypically heterogeneous according to pulsed-field gel electrophoresis analysis. CONCLUSIONS: Cattle faeces contain large numbers of Bacillus spores representing different mesophilic species. Stable faecal populations of particular Bacillus spp. mimicking those found in feed, were subsequently established by feedlotting. SIGNIFICANCE AND IMPACT OF THE STUDY: The results obtained and methods used in this study will help to investigate the indigenous Bacillus composition in the gastrointestinal tract of cattle and will further guide the administration of Bacillus probiotics.