Poly(ADP-ribose) polymerase (PARP-1) is not involved in DNA double-strand break recovery

Background  

The cytotoxicity and the rejoining of DNA double-strand breaks induced by γ-rays, H₂O₂ and neocarzinostatin, were investigated in normal and PARP-1 knockout mouse 3T3 fibroblasts to determine the role of poly(ADP-ribose) polymerase (PARP-1) in DNA double-strand break repair.     

Thyroid oxidase (THOX2) gene expression in the rat thyroid cell line FRTL-5

A cDNA encoding an NADPH oxidase flavoprotein was isolated from the rat thyroid gland. The predicted 1517-residue polypeptide was 82.5% identical to the human THOX2/DUOX2 and 74% similar to THOX1/DUOX1. Rat THOX2 lacks a stretch of 30 residues, corresponding to one exon in the human gene sequence. THOX2 mRNA was found to be expressed in cultured FRTL-5 cells. The level of THOX2 mRNA was increased by cAMP in these cells and it was decreased in the thyroids of rats treated with the antithyroid drug methimazole, unlike the TPO and NIS mRNAs. Since it was found in the intestine, duodenum, and colon, in addition to thyroid, we suggest that it be called LNOX, the new family of long homologs of NOX flavoproteins rather than THOX and/or DUOX.     

Protected polymorphism in the two-locus haploid model with unpredictable fitnesses

 In an unpredictable environment, the distributions of alleles from which polymorphism can be maintained forever belong to a certain set, the C-viability kernel. Such a set is calculated in the two-locus haploid model, as well as the corresponding fitnesses at any time which make this maintenance possible. The dependence of the C-viability kernel on the set U of admissible fitnesses and on the recombination rate r is studied. Notably, the C-viability kernel varies rapidly in the neighborhood of equal fitness of AB and ab; it becomes empty when ab has a fitness below a certain function, which is delineated, of the recombination rate. The properties of the two-locus model under constraints, out of equilibrium and with unpredictable selection are thus presented. Received: 20 May 1999     

Neutral calcium-activated proteases from European sea bass (Dicentrarchus labrax L.) muscle: polymorphism and biochemical studies

Calcium-dependent proteinases or calpains were studied in fish muscle. Hydrophobic chromatography, followed by anion-exchange chromatography of the soluble fraction of sea bass white muscle proteins, resulted in three peaks of calcium-dependent protease activity at neutral pH (A, B and C). They are all neutral cysteine calcium-activated proteinases and can, therefore, be classified as calpain-like enzymes. From the Ca2+ concentration required for activity, A is a mu-calpain, and B and C are m-calpains. They share many properties with calpains from other vertebrate cells but differ in native mass, subunit composition, and the unusual numbers in which they are present. Their specific pattern of expression throughout the year could be of great importance to the resulting rate and extent of degradation of fish flesh after death.     

Large-scale preparation of (9Z,12E)-[1-(13)C]-octadeca-9,12-dienoic acid, (9Z,12Z,15E)-[1-(13)C]-octadeca-9,12,15-trienoic acid and their [1-(13)C] all-cis isomers

Several grams of labelled trans linoleic and linolenic acids with high chemical and isomeric purities (>97%) have been prepared for human metabolism studies. A total of 12.5 g of (9Z, 12E)-[1-(13)C]-octadeca-9,12-dienoic acid and 6.3 g of (9Z,12Z, 15E)-[1-(13)C]-octadeca-9,12,15-trienoic acid were obtained in, respectively, seven steps (7.8% overall yield) and 11 steps (7% overall yield) from 7-bromo-heptan-1-ol. The trans bromo precursors used for the labelling were synthesised by using copper-catalysed couplings. The trans fatty acids were then obtained via the nitrile derivatives. A total of 23.5 g of (9Z,12Z)-[1-(13)C]-octadeca-9, 12-dienoic acid and 10.4 g of (9Z,12Z,15Z)-[1-(13)C]-octadeca-9,12, 15-trienoic acid were prepared in five steps in, respectively, 32 and 18% overall yield. Large quantities of bromo and chloro precursors were synthesised from the commercially available acid according to Barton's procedure. In all cases, the main impurities (>0.5%) of each labelled fatty acid have been characterised.     

Purification and cloning of an arabinogalactan-protein from xylem of loblolly pine

 An arabinogalactan-protein (AGP) was purified from differentiating xylem of loblolly pine (Pinus taeda L.) and the N-terminal sequence used to identify a cDNA clone. The protein, PtaAGP3, was not coded for by any previously identified AGP-like genes. Moreover, PtaAGP3 was abundantly and preferentially expressed in differentiating xylem. The encoded protein contains four domains, a signal peptide, a cleaved hydrophilic region, a region rich in serine, alanine, and proline/hydroxyproline, and a hydrophobic C-terminus. It is postulated to contain a GPI (glycosylphosphatidylinositol) anchor site. If the protein is cleaved at the putative GPI anchor site, as has been observed in other classical AGPs, all but the Ser-Ala-Pro/Hyp-rich domain may be missing from the mature protein. Xylem-specific AGPs are hypothesized to be involved in xylem development. Received: 29 July 1999 / Accepted: 19 August 1999     

Out of Africa and back again: nested cladistic analysis of human Y chromosome variation

We surveyed nine diallelic polymorphic sites on the Y chromosomes of 1,544 individuals from Africa, Asia, Europe, Oceania, and the New World. Phylogenetic analyses of these nine sites resulted in a tree for 10 distinct Y haplotypes with a coalescence time of approximately 150,000 years. The 10 haplotypes were unevenly distributed among human populations: 5 were restricted to a particular continent, 2 were shared between Africa and Europe, 1 was present only in the Old World, and 2 were found in all geographic regions surveyed. The ancestral haplotype was limited to African populations. Random permutation procedures revealed statistically significant patterns of geographical structuring of this paternal genetic variation. The results of a nested cladistic analysis indicated that these geographical associations arose through a combination of processes, including restricted, recurrent gene flow (isolation by distance) and range expansions. We inferred that one of the oldest events in the nested cladistic analysis was a range expansion out of Africa which resulted in the complete replacement of Y chromosomes throughout the Old World, a finding consistent with many versions of the Out of Africa Replacement Model. A second and more recent range expansion brought Asian Y chromosomes back to Africa without replacing the indigenous African male gene pool. Thus, the previously observed high levels of Y chromosomal genetic diversity in Africa may be due in part to bidirectional population movements. Finally, a comparison of our results with those from nested cladistic analyses of human mtDNA and beta-globin data revealed different patterns of inferences for males and females concerning the relative roles of population history (range expansions) and population structure (recurrent gene flow), thereby adding a new sex-specific component to models of human evolution.