The RNA interference pathway affects midgut infection- and escape barriers for Sindbis virus in <Emphasis Type="Italic">Aedes aegypti</Emphasis>

Background  

The RNA interference (RNAi) pathway acts as an innate antiviral immune response in Aedes aegypti, modulating arbovirus infection of mosquitoes. Sindbis virus (SINV; family: Togaviridae, genus: Alphavirus) is an arbovirus that infects Ae. aegypti in the laboratory. SINV strain TR339 encounters a midgut escape barrier (MEB) during infection of Ae. aegypti. The nature of this barrier is not well understood. To investigate the role of the midgut as the central organ determining vector competence for arboviruses, we generated transgenic mosquitoes in which the RNAi pathway was impaired in midgut tissue of bloodfed females. We used these mosquitoes to reveal effects of RNAi impairment in the midgut on SINV replication, midgut infection and dissemination efficiencies, and mosquito longevity.     

Mutational analysis of CDC42Sc, a Saccharomyces cerevisiae gene that encodes a putative GTP-binding protein involved in the control of cell polarity.

The Saccharomyces cerevisiae CDC42 gene product, a member of the ras superfamily of low-molecular-weight GTP-binding proteins, is involved in the control of cell polarity. We have analyzed the effects of three CDC42 mutations (Gly to Val-12, Gln to Leu-61, and Asp to Ala-118) in the putative GTP-binding and hydrolysis domains and one mutation (Cys to Ser-188) in the putative isoprenylation site. The first three mutations resulted in either a dominant-lethal or dose-dependent dominant-lethal phenotype when present on plasmids in haploid cdc42-1ts or wild-type strains. Both wild-type and cdc42-1ts cells carrying plasmids (pGAL) with either the CDC42Val-12 or CDC42Leu-61 alleles under the control of a GAL promoter were arrested with a novel phenotype of large cells with elongated or multiple buds. Cells carrying pGAL-CDC42Ala-118 were arrested as large, round, unbudded cells reminiscent of cdc42-1ts arrested cells. The different phenotype of the CDC42Ala-118 mutant versus the CDC42Val-12 and CDC42Leu-61 mutants was unexpected since the phenotypes of all three analogous ras mutants were similar to each other. This suggests that aspects of the biochemical properties of the Cdc42 protein differ from those of the Ras protein. The cdc42Ser-188 mutant gene was incapable of complementing the cdc42-1ts mutation and was recessive to both wild-type and cdc42-1ts. In double-mutant alleles, the cdc42Ser-188 mutation was capable of suppressing the dominant lethality associated with the three putative GTP-binding and hydrolysis mutations, suggesting that isoprenylation is necessary for the activity of the wild-type and mutant proteins.     

METABOLITES OF [3H]ACETATE BOUND TO SYNAPTIC VESICLES ISOLATED FROM RAT CEREBRAL CORTEX

Abstract— Synaptic vesicles were isolated from rat cerebral cortex after an intraventricular injection of [³H]acetate. The labelled substances bound to the synaptic vesicles were released by exposure to acid, separated from the vesicle membranes by Sephadex column chromatography and identified by thin-layer chromatography and thin-layer electrophoresis. The three major peaks of radioactivity were glutamate, glutamine and gamma-aminobutyric acid. Their presence in synaptic vesicles is consistent with the concept of an integration of energy metabolism, membrane regulation and synaptic transmission.     

A new system for understanding the biodiversity in different nature reserves:capacity,connectivity and quality of biodiversity

In this paper,we propose a new system for understanding the biodiversity in different conservation areas.It includes three aspects:the capacity,the connectivity and the quality.The capacity refers to the numbers of biodiversity,including absolute and relative richness of the vegetation types Nv and Dv = (Nv-1)/lnA,species numbers S and richness of species dGI = (S- 1)/lnA,and germ plasm resources within a nature reserve,and also the potential biological living space offered by the natural resource.It comprises the total biological resources in a nature reserve.The connectivity refers to the flux of biodiversity,including similarity and connected status of the vegetation types SILi = 2z/(x + y) and species numbers SIc = 2z/(x + y) among different nature reserves.The quality refers to the stability of biodiversity,including relative species richness index RSLi = d/dmax,relative vegetation richness index RVLi =Dv/Dmaxv,fastness to invasion species fLi = 1-Si/St,weighted values,representativeness and vulnerability of special vegetations,special species,CITES species and rare species as the protected targets.     

Mutations Affecting Iron Transport in Escherichia coli

A mutant of Escherichia coli K-12 unable to form an essential component of the enterochelin-dependent iron transport system has been isolated. This strain carries a mutation in a gene designated fep, mapping close to two genes, entA and entD, concerned with enterochelin synthesis. Strain AN102, which carries the fep(-) allele, accumulates large quantities of enterochelin and gives a growth response to sodium citrate. The cytochrome b(1) and total iron content, and the measurement of the uptake of (55)Fe(3+), indicate an impairment of the enterochelin-dependent iron transport system. The growth response to sodium citrate is related to the presence, in strain AN102, of an inducible citrate-dependent iron transport system.     

ATP binding and hydrolysis are essential to the function of the Hsp90 molecular chaperone in vivo.

Hsp90 is an abundant molecular chaperone essential to the establishment of many cellular regulation and signal transduction systems, but remains one of the least well described chaperones. The biochemical mechanism of protein folding by Hsp90 is poorly understood, and the direct involvement of ATP has been particularly contentious. Here we demonstrate in vitro an inherent ATPase activity in both yeast Hsp90 and the Escherichia coli homologue HtpG, which is sensitive to inhibition by the Hsp90-specific antibiotic geldanamycin. Mutations of residues implicated in ATP binding and hydrolysis by structural studies abolish this ATPase activity in vitro and disrupt Hsp90 function in vivo. These results show that Hsp90 is directly ATP dependent in vivo, and suggest an ATP-coupled chaperone cycle for Hsp90-mediated protein folding.     

长白山北坡静水水体中水甲虫分布与环境关系的典范对应分析

应用典范对应分析（CCA）对长白山北坡静水水体12个样点中28种水甲虫与环境关系的研究表明,长白山5种环境因子中水底腐殖化程度和海拔对水甲虫的分布起主要作用,与排序轴的相关系灵敏分别高达0.8371和0.7206,而水温和植被密度也有较大的影响,在环境因子的影响下不同生境中水甲虫分布的种群不同,深刻斜凹龙虱,端钩切眼龙虱,布朗沟牙甲,沼梭科水甲虫等主要分布在深水区,与水温没有关系。而异毛龙虱和舟型牙甲等与海拔和水泡子的腐殖化程度呈正相关。