Ultrastructure of Weddellomyces epicallopisma (Dothideales, Dacampiaceae, Ascomycota), especially of its ascospores]

An ultrastructural study of Weddellomyces epicallopisma (ascomata wall, asci, ascospores and vegetative hyphae), the first done on the family Dacampiaceae, confirms most of the observations made in light microscopy. Moreover it shows that ascospores are provided with an endospore (not visible in light microscope) and that the structure of the ascospore septum is more complex. The similarity of the wall structure between the ascospore and the hyphoid appendages, developed on the upper part of the ascoma, is emphasized.     

Evidence for negative regulation of T cell growth by low affinity interleukin 2 receptors

Two experimental situations have been studied, and the results provide evidence for a negative regulatory role for the low affinity interleukin 2 receptor (LA-IL 2R). The IL 2-dependent T helper cell line L-14, deprived of IL 2, becomes quiescent and expresses comparable numbers of high affinity IL 2R (HA-IL 2R) and LA-IL 2R. After activation by recombinant IL 2, this cell line preferentially expresses LA-IL 2R. The IL 2 responsiveness of the L-14 cell line was found to vary according to the ratio of LA-IL 2R to HA-IL 2R: the relative predominance of the LA-IL 2R coincides with a hyporeactivity of cells to IL 2. In contrast, a predominance of HA-IL 2R is accompanied by an increase in cellular IL 2 reactivity. Treatment of three IL 2-dependent T cell lines (L-14, HT-2, and C30.1) with limited amounts of recombinant IL 2 and moderate concentrations of anti-IL 2R monoclonal antibodies stimulates T cell growth. This treatment was shown to selectively diminish the expression of membrane LA-IL 2R. The stimulation was attributed to the decrease of expression of LA-IL 2R.     

Pain, paradox, and value

The author argues that "as soon as one begins to study the understanding and management of pain in science, human medicine, and veterinary medicine, one begins to encounter a variety of apparent paradoxes." He contends that these paradoxes, ten of which he identifies and discusses in this essay, are based on flawed philosophical and valuational assumptions underlying science and medicine. Rollins concludes that, as social morality increasingly has an impact on science, a new ideology will evolve that is more receptive to the moral universe and more capable of a "coherent vision of pain, one which acknowledges that the medical notion of adequacy of anaesthesia is as much a moral as a scientific one."     

Copy number and distribution of P and I mobile elements in Drosophila melanogaster populations

The distribution of the number of copies of P and I transposable elements per genome was investigated by in situ hybridization for a large set of Drosophila melanogaster strains. These included the P, Q and M types of the P-M system of hybrid dysgenesis. P element copy number varied widely (range 5–59). P and Q strains had around 40 copies whereas M strains generally had lower numbers (between 5 and 35) with one extreme value (52). The copy number of I elements appeared to be precisely regulated, as no strains were found outside the 15±5 range. The number of copies of the two families were independent. An excess of P copies on the X chromosome compared with the autosomes was found for the P and Q strains, but not for M strains. Among X-inserted P sites, a very high frequency of occupation was found at the tip of the X chromosome (cytological site 1A), especially for P and Q strains. The possible regulatory role in the P-M system of X-inserted P sites is discussed.     

Cystic fibrosis typing with DNA probes and screening for ΔF508 deletion in families from Southern France

Summary A sample of 235 individuals from 49 French cystic fibrosis (CF) families with at least one living affected child was typed with probes for restriction fragment length polymorphisms (RFLPs) known to be linked to the CF gene, and was screened for the ΔF508 mutation. Using a combination of six probes, 44 out of the 49 families were sufficiently informative to enable prenatal diagnosis or carrier determination. As in many other populations, linkage disequilibrium was found between the CF locus and the haplotype B (XV2c: allele 1; KM19: allele 2), which accounts for about 78% of CF chromosomes in our families. The ΔF508 deletion was present in 64.3% of CF chromosomes.