The role of human demographic history in determining the distribution and frequency of transferase-deficient galactosaemia mutations

Classical or transferase-deficient galactosaemia is an inherited metabolic disorder caused by mutation in the human Galactose-1-phosphate uridyl transferase (GALT) gene. Of some 170 causative mutations reported, fewer than 10% are observed in more than one geographic region or ethnic group. To better understand the population history of the common GALT mutations, we have established a haplotyping system for the GALT locus incorporating eight single nucleotide polymorphisms and three short tandem repeat markers. We analysed haplotypes associated with the three most frequent GALT gene mutations, Q188R, K285N and Duarte-2 (D2), and estimated their age. Haplotype diversity, in conjunction with measures of genetic diversity and of linkage disequilibrium, indicated that Q188R and K285N are European mutations. The Q188R mutation arose in central Europe within the last 20 000 years, with its observed east-west cline of increasing relative allele frequency possibly being due to population expansion during the re-colonization of Europe by Homo sapiens in the Mesolithic age. K285N was found to be a younger mutation that originated in Eastern Europe and is probably more geographically restricted as it arose after all major European population expansions. The D2 variant was found to be an ancient mutation that originated before the expansion of Homo sapiens out of Africa. Heredity (2010) 104, 148-154; doi:10.1038/hdy.2009.84; published online 29 July 2009

Fasciola hepatica: Histological changes in the reproductive structures of triclabendazole (TCBZ)-sensitive and TCBZ-resistant flukes after treatment in vivo with TCBZ and the related benzimidazole derivative, Compound Alpha

Twenty-four shed-reared lambs were each infected orally with 250 metacercariae of Fasciola hepatica, using either the triclabendazole (TCBZ)-sensitive Cullompton isolate or the TCBZ-resistant Sligo isolate. Twelve weeks after infection the lambs were treated with TCBZ (10 mg/kg) or with the experimental fasciolicide, Compound Alpha (Cpd alpha), a benzimidazole derivative of TCBZ (15 mg/kg). The lambs were euthanised 48,72 and 96 h after TCBZ treatment, or 24, 48 and 72 h after Cpd a treatment, and flukes were collected from the liver and/or gall bladder of each animal. Untreated animals harbouring 12-week infections were euthanised 24 h after administration of anthelmintic to the treatment groups, and the untreated flukes provided control material. A semi-quantitative assessment of the degree of histological change induced by the two drugs after different times of exposure was achieved by scoring the intensity of three well-defined lesions that developed in the testes and uteri of a representative sample of flukes from each lamb. In general, it was found that in those tissues where active meiosis and/or mitosis occurred (testis, ovary, and vitelline follicles), there was progressive loss of cell content due to apparent failure of cell division to keep pace with expulsion of the mature or effete products. Further, actively dividing cell types tended to become individualised, rounded and condensed, characteristic of apoptotic cell death. Protein synthetic activity was apparently inhibited in the Mehlis' secretory cells. In the uterus, where successful formation of shelled eggs represents the culmination of a complex sequence of cytokinetic, cytological and synthetic activity involving the vitelline follicles, the ovary and the Mehlis' gland, histological evidence indicating failure of ovigenesis was evident from 24 h post-treatment onwards. The development of these lesions may be related to the known antitubulin activity of the benzimidazole class of anthelmintics, to the induction of apoptosis in cells where mitosis or meiosis has aborted due to failure of spindle formation, and to drug-induced inhibition of protein synthesis. The semi-quantitative findings indicated that Cpd a is slightly less efficacious than TCBZ itself in causing histological damage to the reproductive structures of TCBZ-sensitive flukes, and that, like TCBZ, it caused no histological damage in flukes of the TCBZ-resistant isolate. This study illustrates the potential utility of histological techniques for conveniently screening representative samples of flukes in field trials designed to validate instances of drug resistance or to test the efficacy of new products against known drug-resistant and drug-susceptible fluke isolates. It also provides reference criteria for drug-induced histopathological changes in fluke reproductive structures which may aid interpretation of TEM findings. (C) 2009 Elsevier B.V. All rights reserved.

Analysis of transduction in wastewater bacterial populations by targeting the phage-derived 16S rRNA gene sequences

Bacterial 16S rRNA genes transduced by bacteriophages were identified and analyzed in order to estimate the extent of the bacteriophage-mediated horizontal gene transfer in the wastewater environment. For this purpose, phage and bacterial DNA was isolated from the oxidation tank of a municipal wastewater treatment plant. Phylogenetic analysis of the 16S rRNA gene sequences cloned from a phage metagenome revealed that bacteriophages transduce genetic material in several major groups of bacteria. The groups identified were as follows: Betaproteobacteria, Gammaproteobacteria, Alphaproteobacteria, Actinomycetales and Firmicutes. Analysis of the 16S rRNA gene sequences in the total bacterial DNA from the same sample revealed that several bacterial groups found in the oxidation tank were not present in the phage metagenome (e.g. Deltaproteobacteria, Nitrospira, Planctomycetes and many Actinobacteria genera). These results suggest that transduction in a wastewater environment occurs in several bacterial groups; however, not all species are equally involved into this process. The data also showed that a number of distinctive bacterial strains participate in transduction-mediated gene transfer within identified bacterial groupings. Denaturing gradient gel electrophoresis analysis confirmed that profiles of the transduced 16S rRNA gene sequences and those present in the whole microbial community show significant differences.