Effect of Tooth Removal on Recaptures of Raccoons

Abstract: Researchers have extensively used mark—recapture techniques to obtain information on demographic parameters of wildlife populations. However, researchers have recognized that a number of factors can influence capture probabilities of wildlife species, which in turn can bias mark—recapture estimates of demographic parameters. Tooth extraction, which is a commonly used technique in studies of mesopredator species to obtain precise age estimates and to monitor the use of vaccine baits, is an aspect of animal handling that clearly might affect the recapture probability of individuals. However, the effect that tooth removal has on the individual recapture probabilities of wildlife species is unknown. During 2005, we trapped and marked 91 raccoons (Procyon lotor) in northern Indiana, USA, as part of a mark—recapture study designed specifically to determine if tooth extractions have an effect on recapture probabilities of individuals. We performed tooth extractions on 50% of the raccoons at the time of capture, and we attempted to balance tooth extractions with respect to sex and age of raccoons. We used logistic regression to model the effects of sex, age, and tooth removal on recapture probabilities, and we used Mann—Whitney U-tests to examine the effect of tooth removal on the number of times we recaptured individuals. The probability of recapture differed between sexes but did not differ as a function of tooth removal or among age classes. In addition, we failed to detect any difference in the mean number of times that we recaptured raccoons between the tooth removed and non—tooth-removed groups. Our results suggest that managers can use tooth extractions as an effective management tool without biasing population estimates or compromising other management objectives.     

The intrinsic flexibility of the aptamer targeting the ribosomal protein S8 is a key factor for the molecular recognition

Background

Aptamers are RNA/DNA biomolecules representing an emerging class of protein interactors and regulators. Despite the growing interest in these molecules, current understanding of chemical-physical basis of their target recognition is limited. Recently, the characterization of the aptamer targeting the protein-S8 has suggested that flexibility plays important functional roles. We investigated the structural versatility of the S8-aptamer by molecular dynamics simulations.

The first world swimming championships of roseobacters—Phylogenomic insights into an exceptional motility phenotype

Many marine Alphaproteobacteria of the Roseobacter group show a characteristic swim-or-stick lifestyle, for which motility is a crucial trait. Three phylogenetically distinct flagellar gene clusters (FGCs) have been identified in Rhodobacteraceae that have been named fla1, fla2 and fla3 according to their relative abundance. In addition to the flagellar-dependent swimming and swarming motility, pilus-dependent twitching mediates bacterial locomotion. Furthermore, filament independent modes of motility, namely gliding and sliding, have been described for various microorganisms. However, no mode of motility other than swimming has so far been described for roseobacters. In the present study, we investigated motility, distribution of flagellar systems and the phylogeny of 120 genome-sequenced Rhodobacteraceae. The phylogenetically broad taxon sampling that included 114 type strains revealed the presence of at least ten distinct clades that were statistically well supported. The investigation of the actual physiological capacity for swimming motility on soft agar plates showed that only about half of the 120 tested strains were motile under the tested conditions. Seven strains developed a conspicuous dendritic motility phenotype that was reminiscent of the swarming motility in Pseudomonas aeruginosa. The observed dendritic motility in two strains (i.e. Sulfitobacter pseudonitzschiae DSM 26842 and Roseovarius pacificus DSM 29589) was particularly surprising because they did not harbor any genes of the FGC. Accordingly, it was concluded that this form of dendritic motility was independent of a flagellum. A comparative genomics approach allowed a remarkable number of pilus-related candidate genes to be identified for this novel type of motility in Rhodobacteraceae.     

一种结合SELEX与二代测序技术筛选RNA结合蛋白特异识别序列新方法的建立

RNA结合蛋白通过特异识别RNA底物发挥重要的生物学作用。指数富集的配体系统进化(Systematic evolution of ligands by exponential enrichment,SELEX)技术是一种体外筛选核酸底物的基本方法,SELEX技术通过重复多轮筛选从随机核酸序列库中筛选出特异性与靶物质高度亲和的核酸底物,本研究将利用该技术与二代高通量测序(NGS)相结合,体外合成含有20个随机碱基的RNA文库,将所要研究的蛋白构建到带有可被链亲和酶素磁珠捕获的SBP标记的载体上去,显著提高筛选效率,仅需1轮筛选即可获得所需RNA底物motif。通过该方法获得了人的hn RNP A1的UP1结构域特异识别AGG和AG二种RNA序列,并通过EMSA实验证实其可以与获得的RNA motif结合。这一方法的建立对于研究RNA结合蛋白识别底物的序列特异性,并进一步了解其在生物体内的调控机制有重要意义。     

Phosphatidylcholine and cholesterol interactions in model membranes

Various phosphatidylcholines differing either in the stereochemistry around their chiral center or in the position of a cis double bond along the acyl chains were synthesized in order to study critical contact regions in the phospholipid molecule with adjacent cholesterol in model membranes. Microviscosities calculated from fluorescence depolarization of diphenylhexatriene and chain order from spin label studies were measured to monitor physical membrane properties. The enhancing effect of cholesterol on the microviscosity of membranes containing phosphatidylcholines with comparable acyl chain length was largest when the two acyl chains were saturated and smallest when both were unsaturated. Membranes prepared from phosphatidylcholines having a single cis double bond at different positions along the sn-2 acyl chain showed roughly the same changes of microviscosity or chain order upon incorporation of cholesterol. No discrimination was evident in the interaction between cholesterol and enantiomeric phosphatidylcholines or between the enantiomeric phosphatidylcholine molecules themselves. We conclude that the rigidifying effect of cholesterol in membranes does not depend on specific sites of interaction and that with respect to physical membrane properties phosphatidylcholine behaves as an achiral molecule.     

Evidence for plasmid-associated crystal toxin production in Bacillus thuringiensis subsp. israelensis

Three crystalliferous (Cry⁺) strains of Bacillus thuringiensis subsp. israelensis (serotype 14) that produce parasporal protein crystals toxic to dipteran larvae and several acrystalliferous (Cry^?) mutants, either induced or spontaneously derived from a single Cry⁺ parent, were examined for the presence of covalently closed circular (CCC) DNA in attempts to correlate toxin production with the presence of a specific plasmid. The plasmid profiles of both Cry⁺ and Cry^? variants were analyzed by both a cleared lysate- and a modified Eckhardt lysateelectrophoresis technique. All of the Cry^? mutants derived from the Cry⁺ parental strain had lost a 4.0- to 4.4-megadalton (Mdal) plasmid. Bioassay data confirmed loss of toxin production by the Cry^? variants. All three Cry⁺ strains, including the parent of the Cry^? strains, contained CCC plasmids DNAs of the following approximate molecular weights: 4.0 to 4.4, 5.2 to 6.0, and 11.4 to 13.0 Mdal. One Cry⁺ strain contained an additional CCC plasmid of 6.7 to 7.2 Mdal. The plasmid patterns for several Cry^? derivatives differed in other respects from the pattern for their parent strain. The various Cry⁺ and Cry^? strains could be distinguished either by phenotypical differences in antibiotic sensitivity, crystal production, and toxicity, or by differences in their plasmid profiles.     

Structural elucidation and partial synthesis of 3-hydroxyheterodendrin,a cyanogenic glucoside from Acacia sieberiana var. woodii

A new cyanogenic glucoside, isolated from pods of Acacia sieberiana var. woodii, was shown to be (2R)-2- (β-d-glucopyranosyloxy)-3-hydroxy-3-methylbutanenitrile by spectroscopic and chemical methods. The absolute configuration of this glucoside was correlated with that of proacacipetalin by oxymercuration of the latter, followed by borohydride reduction of the product.