Worms taste bitter: ASH neurons, QUI-1, GPA-3 and ODR-3 mediate quinine avoidance in Caenorhabditis elegans

An animal's ability to detect and avoid toxic compounds in the environment is crucial for survival. We show that the nematode Caenorhabditis elegans avoids many water-soluble substances that are toxic and that taste bitter to humans. We have used laser ablation and a genetic cell rescue strategy to identify sensory neurons involved in the avoidance of the bitter substance quinine, and found that ASH, a polymodal nociceptive neuron that senses many aversive stimuli, is the principal player in this response. Two G protein alpha subunits GPA-3 and ODR-3, expressed in ASH and in different, nonoverlapping sets of sensory neurons, are necessary for the response to quinine, although the effect of odr-3 can only be appreciated in the absence of gpa-3. We identified and cloned a new gene, qui-1, necessary for quinine and SDS avoidance. qui-1 codes for a novel protein with WD-40 domains and which is expressed in the avoidance sensory neurons ASH and ADL.     

The spatial organization of apolipoprotein A-I on the edge of discoidal high density lipoprotein particles: a mass specrometry study

The three-dimensional structure of human apoA-I on nascent, discoidal HDL particles has been debated extensively over the past 25 years. Recent evidence has demonstrated that the alpha-helical domains of apoA-I are arranged in a belt-like orientation with the long axis of the helices perpendicular to the phospholipid acyl chains on the disc edge. However, experimental information on the spatial relationships between apoA-I molecules on the disc is lacking. To address this issue, we have taken advantage of recent advances in mass spectrometry technology combined with cleavable cross-linking chemistry to derive a set of distance constraints suitable for testing apoA-I structural models. We generated highly homogeneous, reconstituted HDL particles containing two molecules of apoA-I. These were treated with a thiol-cleavable cross-linking agent, which covalently joined Lys residues in close proximity within or between molecules of apoA-I in the disc. The cross-linked discs were then exhaustively trypsinized to generate a discrete population of peptides. The resulting peptides were analyzed by liquid chromatography/mass spectrometry before and after cleavage of the cross-links, and resulting peaks were identified based on the theoretical tryptic cleavage of apoA-I. We identified at least 8 intramolecular and 7 intermolecular cross-links in the particle. The distance constraints are used to analyze three current models of apoA-I structure. The results strongly support the presence of the salt-bridge interactions that were predicted to occur in the "double belt" model of apoA-I, but a helical hairpin model containing the same salt-bridge docking interface is also consistent with the data.     

中国的炭疽杆菌DNA分型及其地理分布

炭疽广泛分布于中国各地,特别是西部地区,并经常造成人畜疾病,在一项合作研究中,用多位点VNTR分析（MLVA）对从1952-1998年自中国主要地理流行区域分离的病人,病畜和土壤等来源的炭疽杆菌进行了基因分型,MLVA分析结果揭示了21种新的基因型,其等位基因组合在以前世界范围分离物的研究中未曾发现,此外,分离物的分群显示,A3b组是地理上最广泛分布的基因组,说明该组可能是中国的“地方流行株”。而来自古丝绸之路重要贸易中心新疆的大量分离株其基因型特别分散。     

Retrospective analysis of an outbreak of B virus infection in a colony of DeBrazza's monkeys (Cercopithecus neglectus)

In 1981, an outbreak of herpetic disease developed in a colony of DeBrazza's monkeys (Cercopithecus neglectus). In seven of eight infected animals, clinical signs of infection included vesicular and ulcerative lesions on the lips, tongue, and/or palate. Histologic examination of lesions revealed intranuclear inclusion bodies, and electron microscopy revealed nucleocapsids and virions with typical herpesvirus morphology. Although a virus was isolated that appeared similar to monkey B virus, techniques available at the time did not allow precise identification of the virus. Analysis of serum from one surviving monkey collected 12 years after the outbreak revealed a pattern of reactivity characteristic of B virus-positive serum on the basis of results of ELISA and western immunoblot analysis. Polymerase chain reaction analysis of archived paraffin-embedded tissue specimens and molecular analysis of the one viral isolate obtained from a DeBrazza's monkey indicated that the virus responsible for the outbreak was a new genotype of B virus. Testing of sera from lion-tailed macaques (Macaca silenus) housed in an adjacent cage at the same zoo indicated that these animals harbored this virus and, thus, were the likely source of the virus that infected the DeBrazza's monkeys. This study documents usefulness of archiving samples from disease outbreaks for later analysis. In addition, this incident underscores the importance of considering herpes B virus infection when outbreaks of disease having characteristics of herpetic infections develop in nonhuman primates kept at institutions that also house macaques.     

B-virus specific-pathogen-free breeding colonies of macaques (Macaca mulatta): retrospective study of seven years of testing.

BACKGROUND AND PURPOSE: National Institutes of Health's Division of Comparative Medicine has sponsored a multi-institutional program for the establishment of specific-pathogen-free (SPF) macaque colonies. B virus (Herpesvirus simiae, Cercopithecine herpesvirus type 1) has been targeted in this surveillance. Participating institutions have established individual timetables for frequency of testing and types of monitoring and husbandry techniques, all with the common goal of producing pathogen-free monkeys for research. The greatest biosecurity threat to the program comes from failure to detect seronegative latent infections, either in first-year macaques or macaques introduced in subsequent years, although these are supposed to operate as closed colonies. METHODS: From January 1990 through December 1996, we screened macaques for B virus, using enzyme-linked immunoabsorbant assay (ELISA) and Western blot analysis. RESULTS: During the first year, 1,097 macaques from six colonies were tested, and 88.4% tested negative for B virus. During the seventh year, 1,843 were tested, of which 99.7% tested negative. Seropositive macaques were detected as late as the seventh year. CONCLUSIONS: An aggressive program to establish an SPF colony of captive breeding macaques can be effective in reducing the risk of B-virus exposure.