Boring Forminifera in French Polynesian coral reefs

The discovery of epipsammitic Foraminifera in sediments of Moorea and Scilly (French Polynesia) and the study of close relationships between embedded specimens and host-grains indicate that some species participate in the weakening and subsequent breakdown of skeletal grains and consequently contribute to the production of silt-sized particles. The study of 36 stations around the islands shows the factors that control the distribution and abundance of this incrusted microfauna. Specimens are more abundant on sand particles larger than 1,000 microns and in the high energy areas; this abundance decreases with depth. The physiological mechanism of penetrations is presumably chemical, but each species apparently has its own process: complete dissolution with removal of ions for the cytoplasm of calcareous species; partial dissolution with transport of silt-size aggregates on the test of agglutinated species. The purpose of such penetration may be to protect themselves against water turbulence and to provide material for test construction.     

Evolution of the immunodominant domain of the circumsporozoite protein gene from Plasmodium vivax. Implications for vaccines

Recent work directed toward the development of a malarial vaccine has focused on the identification and production of the immunodominant repeating peptide of the circumsporozoite protein of the human malaria parasites as an antigen. An important factor which relates to the usefulness of this antigen in a vaccine is the rate at which the molecule changes in sequence. We have determined the sequence and arrangement of the repeating epitope of the circumsporozoite protein gene from a Plasmodium vivax isolate from La Paz, El Salvador (Sal-I). This is compared with a portion of the previously published sequence of the circumsporozoite protein gene from a P. vivax isolate from Belém, Brazil. The genes appear to be very similar in the repeat region. There are 20 similar repeating units in the El Salvador strain and only 19 units are conserved in the Brazilian strain. Following this there are degenerate repeats in both strains. Even the pattern of silent mutations in the repeat area are similar; however, they are not necessarily in the identical location and appear to have shifted. The data suggest that the repeat region of these genes may be evolving by an accelerated mechanism(s). Such a phenomenon could severely decrease the long-term efficacy of a repeat-based anti-sporozoite vaccine.     

Frequency of Escherichia coli O157:H7 isolation from stool specimens

During a 6-month period, 7252 faeces specimens were examined for Escherichia coli serotype O157:H7. Forty-nine specimens (0.7%) from 19 patients yielded this organism. Escherichia coli O157:H7 was the third most frequently isolated bacterial pathogen, following Campylobacter jejuni and (or) Salmonella sp. Although regional variation between laboratories determined whether Campylobacter jejuni or Salmonella was the primary bacterial pathogen isolated, E. coli O157:H7 was consistently isolated more frequently than either Shigella or Yersinia enterocolitica.     

Effect of butaclamol enantiomers on hypothalamic tyrosine hydroxylase in the rat brain

The authors demonstrate stereospecificity of the action of butaclamol enantiomers on substrate inhibition of hypothalamic tyrosine hydroxylase (TH) and regulation of the tyrosine hydroxylase response by the presynaptic membrane (presynaptic receptors) of rat hypothalamus synaptosomes under membrane activation with dopamine. The effect of (+)-butaclamol on the substrate inhibition of TH was noticeable at a concentration of 10(-8)M, reaching a maximum at 10(-5)M. (-)-Butaclamol administered at the same concentrations did not influence the substrate inhibition of the enzyme. (+)-Butaclamol added to the incubation medium containing hypothalamic synaptosomes concurrently with dopamine (10(-5)M) completely blocked the regulatory action of the latter on TH, with this action mediated via presynaptic receptors. (-)-Butaclamol (10(-5)M) antagonized the action of dopamine under the same conditions. The data obtained indicate high stereo-specificity of butaclamol enantiomers as regards their effect on presynaptic regulation of TH, suggesting that elimination of the substrate inhibition of hypothalamic TH is a stereoselective effect of neuroleptics and can be a prognostically important criterion in the appraisal of compounds with potential neuroleptic activity.     

Carry-over of deoxynivalenol into eggs of laying hens — Preliminary results

Carry-over of deoxynivalenol (DON) into eggs was investigated within the scope of a 16-week experiment with laying hens, in which the birds were fed a maize-based diet containing DON at 11.9 mg/kg dry matter. Eggs were collected during weeks 2, 4, 8, and 16. DON and its metabolite deepoxy-DON were analysed separately in freeze-dried yolk and albumen. Yolk was extracted with water and the extract was purified using an immunoaffinity column (IAC). Albumen was extracted with acetonitrile-water and the extract was pre-cleaned before applying an IAC. All albumen and some yolk samples were incubated with β-glucuronidase prior to extraction. DON and de-epoxy-DON were determined by high performance liquid chromatography (HPLC) with diode array detection (DAD). The detection limits of both toxins were 20 ng/g and 15 ng/g in freezedried yolk and albumen, respectively, corresponding to approximately 10 ng/g and 2 ng/g in fresh samples. The recovery of DON/de-epoxy-DON in spiked samples (50–200 ng/g) was 87/83% (yolk) and 87/77% (albumen) with coefficients of variation of 4–15%. Neither DON nor de-epoxy-DON were detected in any of the samples. In order to achieve lower detection limits, the methods are currently optimized. However, these preliminary results indicate that eggs do not contribute significantly to the dietary DON intake of the consumer. Presented at the 26^th Mykotoxin-Workshop in Herrsching, Germany, May 17–19, 2004