The Dominant white, Dun and Smoky color variants in chicken are associated with insertion/deletion polymorphisms in the PMEL17 gene

Dominant white, Dun, and Smoky are alleles at the Dominant white locus, which is one of the major loci affecting plumage color in the domestic chicken. Both Dominant white and Dun inhibit the expression of black eumelanin. Smoky arose in a White Leghorn homozygous for Dominant white and partially restores pigmentation. PMEL17 encodes a melanocyte-specific protein and was identified as a positional candidate gene due to its role in the development of eumelanosomes. Linkage analysis of PMEL17 and Dominant white using a red jungle fowl/White Leghorn intercross revealed no recombination between these loci. Sequence analysis showed that the Dominant white allele was exclusively associated with a 9-bp insertion in exon 10, leading to an insertion of three amino acids in the PMEL17 transmembrane region. Similarly, a deletion of five amino acids in the transmembrane region occurs in the protein encoded by Dun. The Smoky allele shared the 9-bp insertion in exon 10 with Dominant white, as expected from its origin, but also had a deletion of 12 nucleotides in exon 6, eliminating four amino acids from the mature protein. These mutations are, together with the recessive silver mutation in the mouse, the only PMEL17 mutations with phenotypic effects that have been described so far in any species.     

Sequence polymorphism in a novel noncoding region of Pacific oyster mitochondrial DNA

Nucleotide sequence polymorphism in a 641-bp novel major noncoding region of mitochondrial DNA (mtDNA-NC) of the Pacific oyster Crassostrea gigas was analysed for 29 cultured individuals within the Goseong population. A total of 30 variable sites were detected, and the relative frequency of nucleotide alteration was determined to be 4.68. Alterations were mostly single nucleotide substitutions. Transition, transversion, both transition and transversion, and both transversion and nucleotide deletion were observed at 18, 9, 2 and 1 sites, respectively. Among 29 specimens, 22 haplotypes were identified, and pairwise genetic diversity of haplotypes was calculated to be 0.988 from multiple sequence substitutions using the two-parameter model. A phylogenetic tree, obtained for haplotypes by the neighbor-joining method, showed a single cluster of linkages. The cluster comprised 11 haplotypes associating with 14 specimens, while the other 11 haplotypes associating with 15 specimens were scattered. This mtDNA-NC presenting a high nucleotide sequence polymorphism is a potential mtDNA control region. It therefore can serve as a genetic marker for intraspecies phylogenetic analysis of the Pacific oyster and is more useful than the less polymorphic mtDNA coding genes.     

VEGF and bFGF mRNA Are Expressed in Ethylnitrosourea-Induced Experimental Rat Gliomas

1. Which angiogenic growth factors actually mediate tumor growth in ethylnitrosourea (ENU)-induced gliomas in rats was examined.2. In situ hybridization histochemistry with digoxigenin-labeled oligonucleotide probes was used to investigate the cellular expression and distribution of vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF) mRNAs in ENU-induced gliomas.3. Both VEGF and bFGF mRNAs were not detected in normal gial cells but in ENU-induced glioma cells.4. Our results suggest that the growth of ENU-induced glioma may be regulated by multiple angiogenic growth factors and that these gliomas may proliferate by synthesizing such growth factors.     

Inhibition of Epstein-Barr virus infection in vitro and in vivo by soluble CR2 (CD21) containing two short consensus repeats.

The extracellular domain of CR2, the Epstein-Barr virus (EBV)/C3d receptor of B lymphocytes, contains 15 or 16 tandemly arranged short consensus repeat elements (SCR). Recombinant CR2 proteins containing SCR 1 and 2 fused to Staphylococcus aureus protein A (PA-CR2) and to murine complement factor H SCR 20 (CR2FH) were expressed in Escherichia coli and in insect cells, respectively. These recombinant CR2 molecules retained functional activity as indicated by their ability to bind to C3dg in an enzyme-linked immunosorbent assay and to inhibit EBV gp350/220 binding to B cells. PA-CR2 and CR2FH were as efficient in blocking EBV gp350/220 binding as the full-length CR2 extracellular domain, indicating that the first two SCR of CR2 contain the majority of the ligand binding activity of the receptor. PA-CR2 and CR2FH inhibited EBV-induced B-cell proliferation in vitro and blocked the development of EBV-induced lymphoproliferative disease in severe combined immunodeficient mice reconstituted with human lymphocytes. These studies indicate that soluble forms of truncated CR2 proteins may have potential therapeutic value in the treatment of EBV-induced lymphoproliferative disorders in humans that involve viral replication.     

Chromosome analysis of bone marrow in mammals after treatment with isoniazid

Summary Cytogenetic investigations in bone marrow from animals treated with isoniazid (INH) were performed in seven different laboratories according to a standard protocol. The experiments were carried out in the Chinese hamster, the mouse, and the rat. In short-term studies INH was administered twice at an interval of 24 h in doses of 5, 25, and 125 mg/kg, and the animals were sacrificed 6, 12, 24, and 48 h after the second dose. In long-term studies doses of 25 and 125 mg/kg were administered thrice weekly for 12 weeks. As a rule, each group consisted of at least four animals, and 100 metaphases per animal were counted. Statistical analysis of the data showed that the incidence of chromosomal aberrations including gaps lay in the critical range for two groups in one laboratory and was significantly higher than in the control in three groups in another of the seven laboratories. From the results of both the short-term and the long-term studies in all laboratories, however, it may be concluded, that isoniazid does not induce gross chromosomal aberrations.     

Carbon Dioxide and Methane Emissions from Peat Soil in an Undrained Tropical Peat Swamp Forest

Ecosystems - This study investigates the factors controlling the soil CO2 and CH4 fluxes and quantifies annual cumulative soil respiration (RS), heterotrophic respiration (RH), and soil CH4...