Intermittent shedding of thermophilic campylobacters by sheep at pasture

The rates at which sheep on different types of pasture shed campylobacters in their faeces were measured over 12 months. Overall, shedding of campylobacters at pasture was between a third and a half of the carriage rate (92%) of the intestines of sheep at slaughter. Shedding was highest during saltmarsh grazing, followed by upland fell and farm grazing. The rate of shedding varied at different times of the year, with the highest rates (100%) coinciding with lambing, weaning, and movement onto new pasture. The lowest rates (0%) occurred when sheep were fed on hay and silage. On the farm, low rates occurred during the whole of gestation, both when the sheep were indoors and outdoors. Campylobacter jejuni was the main species isolated and survived for up to 4 d in sheep faeces. Lambs became colonized by Campylobacter within 1-5 d of being born. Ewes, which were not shedding campylobacters prior to lambing, started to shed after lambing, and ewes which were shedding low numbers of Campylobacter before lambing, increased the numbers of bacteria being shed after lambing.     

Developmental distribution of the polyadenylation protein CstF-64 and the variant tauCstF-64 in mouse and rat testis

Messenger RNA polyadenylation is one of the processes that control gene expression in all eukaryotic cells and tissues. In mice, two forms of the regulatory polyadenylation protein CstF-64 are found. The gene Cstf2 on the X chromosome encodes this form, and it is expressed in all somatic tissues. The second form, tauCstF-64 (encoded by the autosomal gene Cstf2t), is expressed in a more limited set of tissues and cell types, largely in meiotic and postmeiotic male germ cells and, to a smaller extent, in brain. We report here that whereas CstF-64 and tauCstF-64 expression in rat tissues resembles their expression in mouse tissues, significant differences also are found. First, unlike in mice, in which CstF-64 was expressed in postmeiotic round and elongating spermatids, rat CstF-64 was absent in those cell types. Second, unlike in mice, tauCstF-64 was expressed at significant levels in rat liver. These differences in expression suggest interesting differences in X-chromosomal gene expression between these two rodent species.     

The O-specific chain structure of the major component from the lipopolysaccharide fraction of Halomonas magadii strain 21 MI (NCIMB 13595)

An O-specific polysaccharide containing D-galactose and D-glucose, was isolated from the water-soluble lipopolysaccharide fraction of the alkaliphilic bacterium Halomonas magadii. The structure, determined by means of chemical analysis and 1D and 2D NMR spectroscopy, showed a trisaccharide repeating unit, as shown below: [structure: see text]     

Field-induced reorganization of the neural membrane lipid bilayer: a proposed role in the regulation of ion-channel dynamics

We present a computational model demonstrating that an electric field propagating in the plane of the neural membrane during transmembrane ion movement creates lateral concentration gradients of the lipids. Due to this field-induced reorganization, ethenes of the lipid chains become aligned and polarized. This finding is interpreted within the context of molecular studies of protein folding in biological membranes. We propose that electrostatic interactions between membrane dipoles and charged amino acid residues of the unfolded ion-channel protein regulate protein-folding kinetics (channel closing). These electrostatic interactions thus regulate electrical signaling in neurons.     

Identifying epidemiological factors affecting sea lice Lepeophtheirus salmonis abundance on Scottish salmon farms using general linear models

The variation in Lepeophtheirus salmonis sea lice numbers across 40 Scottish salmon farm sites during 1996 to 2000 was analysed using mean mobile abundance for 3 important 6 mo periods within the production cycle. Using statistical regression techniques, over 20 management and environmental variables suspected to have an effect on controlling lice populations were investigated as potential risk factors. The findings and models developed provide a picture of mobile L. salmonis infestation patterns on Scottish farm sites collectively. The results identified level of treatment, type of treatment, cage volume, current speed, loch flushing time and sea lice levels in the preceding 6 mo period to be key explanatory factors. Factors such as stocking density, site biomass, water temperature and the presence of neighbours, previously cited to be important correlates of sea lice risk from analysis of individual sites over time, were not found to be important. Variation in mobile abundance in the first half of the second year of production could be adequately explained (adjusted R2 between 55 and 72%) by the recorded data, suggesting that there is scope for management to control L. salmonis abundance, though much of the variation remains unexplained.     

Circadian dynamics of cytosolic and nuclear Ca2+ in single suprachiasmatic nucleus neurons

Intracellular free Ca(2+) regulates diverse cellular processes, including membrane potential, neurotransmitter release, and gene expression. To examine the cellular mechanisms underlying the generation of circadian rhythms, nucleus-targeted and untargeted cDNAs encoding a Ca(2+)-sensitive fluorescent protein (cameleon) were transfected into organotypic cultures of mouse suprachiasmatic nucleus (SCN), the primary circadian pacemaker. Circadian rhythms in cytosolic but not nuclear Ca(2+) concentration were observed in SCN neurons. The cytosolic Ca(2+) rhythm period matched the circadian multiple-unit-activity (MUA)-rhythm period monitored using a multiple-electrode array, with a mean advance in phase of 4 hr. Tetrodotoxin blocked MUA, but not Ca(2+) rhythms, while ryanodine damped both Ca(2+) and MUA rhythms. These results demonstrate cytosolic Ca(2+) rhythms regulated by the release of Ca(2+) from ryanodine-sensitive stores in SCN neurons.     

Author Index for Neurochemical Research,Volume 29, 2004

Author Index

Author Index for Neurochemical Research, Volume 29, 2004