Biochimie
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The transcriptional activation of heat shock protein (HSP) genes is initiated by the binding of heat shock factors (HSFs) to heat shock elements (HSEs) located at the promotor regions. Multiple HSFs exist in larger eukaryotic organisms in order to sense various types of stress signals. Here we report the cloning of zebrafish (Danio rerio) HSF2 (zHSF2) cDNA (GenBank accession number AF412833 ) that has an open reading frame of 1470 nucleotides, encoding a polypeptide of 489 amino acids. ⋯ Recombinant zHSF2 bound with a very high specificity to HSEs arranged as inverted arrays of 5'-nGAAn-3', as replacing one GAA with GTA almost abolished the formation of HSE-binding complex. Similar patterns of zHSF1a and zHSF2 mRNA expression in the brain regions of developing zebrafish were detected by whole mount in situ hybridization and paraffin sectioning, suggesting that most of the two HSF gene activities were controlled by a common mechanism during the embryonic development of zebrafish. The levels of both zHSF1a and zHSF2 mRNA in zebrafish tissues were moderately increased after heat stress.
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Antigens of the ABH and Lewis histo-blood group family have been known for a long time. Yet their biological meaning is still largely obscure. Based on the available knowledge about the genes involved in their biosynthesis and about their tissue distribution in humans and other mammals, we discuss here the selective forces that may maintain or propagate these oligosaccharide antigens. ⋯ In contrast, the genes of low frequency polymorphism are expected to play roles at the cellular level, although they may be dispensable at the individual level. In addition, some members of these three gene families are expected to be functionally redundant and may either provide a reservoir for additional diversity in the future or become inactivated. We also discuss the role of the ABH and Lewis histo-blood group antigens in pathologies such as cancer and cardiovascular diseases, but argue that it is merely incidental and devoid of evolutionary impact.
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Spider venoms are complex mixtures of neurotoxic peptides, proteins and low molecular mass organic molecules. Their neurotoxic activity is due to the interaction of the venom components with cellular receptors, in particular ion channels. ⋯ Following diverse molecular evolution mechanisms, and in particular selective hypermutation, short spider peptides appear to have functionally diversified while retaining a conserved molecular scaffold. This paper reviews the composition and pharmacology of spider venoms with emphasis on polypeptide toxin structure, mode of action and molecular evolution.
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An alkylating analogue of NADP+ the 3-chloroacetylpyridine adenine dinucleotide phosphate was prepared from 3-diazoacetylpyridine adenine dinucleotide phosphate which was obtained by enzymatic transglucosidation of NADP+. The 3-diazoacetylpyridine adenine dinucleotide phosphate proved to be more unstable when compared to the corresponding NAD+ analogue. The alkylation of several dehydrogenases using this alkylating analogue is mentioned.
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Comparative Study
[Primary structure of the alpha chain of the major component of goose hemoglobins (Anser anser)].
Utilising the homology between goose alpha chain hemoglobin and chicken, the primary arrangement of the amino acid residues of the alpha chain (major component) of goose hemoglobin is presented. Data were obtained from amino acid analysis of the isolated alpha chain and of tryptic peptides of the chain. Their chemical structure was established by Edman degradation, carboxypeptidase A and B and leucineaminopeptidase digestion.