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Biochemical Genetics (v.39, #11-12)
Differential Esterase Expression in Developmental Mutants of Aspergillus nidulans by Maria de Fátima P. S. Machado; Marialba A. A. de Castro-Prado (pp. 357-368).
Esterase isozymes were used to detect substrate-preference polymorphism in five strains of Aspergillus nidulans, and to show differential gene expression in developmental mutants in response to 5-azacytidine treatment. The medusa mutants B116, SM23, and M25 were selected in the presence of 5-azacytidine (5AC); also the G839 bristle mutant obtained in the absence of 5AC as well as the UT196 master strain and the normal segregant SM24 were used for the esterase studies. The esterase isozyme patterns of the A. nidulans strains observed with 4-methylumbelliferyl esters and α- and β-naphthyl esters indicated a total of 18 isoesterases. Substrate preference for either 4-methylumbelliferyl esters and α- or β-naphthyl esters was observed. Similarity between the different A. nidulans genotypes was 84.4–100%. The genomic similarity of the B116, SM23, and M25 mutant strains (100%) supports previous observations that specific DNA sequences might be targets for 5AC action in this filamentous fungus, and the differential expression of the Est-4 isozyme in the medusa developmental mutant and the Est-2 isozyme specifically detected in the bristle mutant G839 seems to indicate esterase isozymes as possible markers of biochemical differences among different developmental mutants of A. nidulans.
Keywords: isozymes; filamentous fungus; developmental mutants; 5-azacytidine; isoesterases
Cloning, Tissue Expression Pattern, and Chromosome Location of a Novel Human Gene BRI3BP by Lizhu Lin; Yimin Wu; Changben Li; Shouyuan Zhao (pp. 369-377).
A novel cDNA fragment was identified from a human fetal brain cDNA library by using the coding sequence of human BRI3 gene (Accession No. NM015379) as bait in a yeast two-hybrid screening. Then by 5′-RACE (rapid amplification of cDNA end) and electronic hybridization, we obtained a 1.9 kb contig which consists of a novel gene. It was designated as BRI3BP by the HUGO Nomenclature Committee. It contains an open reading frame encoding 251 amino acids. The calculated molecular weight of the deduced protein is 27.8 kU. The predicted isoelectric point is 9.48. Northern hybridization showed its mRNA was highly expressed in brain, kidney, and liver. By RH mapping, the BRI3BP gene was mapped to human chromosome 12q24.2-qter.
Keywords: BRI3BP; cDNA cloning; tissue expression pattern; RH mapping
Analysis of Genetic Factors Associated with Nitric Oxide Production in Mice by Gene P. Ables; Noriyuki Hamashima; Tomomasa Watanabe (pp. 379-394).
Different mouse strains possessing the Nramp1 r allele, which were theoretically expected to have relatively high nitric oxide (NO) production after cytokine stimulation, were used to analyze the genetic factors associated with NO production. After gamma interferon and lipopolysaccharide stimulation, the strains NZB/N, DBA/2N, AKR/N, and A/J showed significantly low NO production; NJL, 129/J, MOG, SJL/J, CBA/N, and NOD/Shi had moderate amounts; and C3H/He and SPR had the highest levels as compared to the other mice. The F1 progeny of A/J × C3H/He and AKR/N × C3H/He showed significantly higher NO production, whereas the F1 progeny of DBA/2N × C3H/He produced a relatively low amount. Furthermore, the backcross progeny from their F1 showed variations in NO production, and therefore it was speculated that the regulation of NO production is polygenic. Genetic typing experiments related to the NO production in the backcross progeny demonstrated significant deviations to some genetic microsatellite markers. Sequencing of the iNOS promoter regions of the Nramp1 r strains to examine the relationship with NO production revealed that MOG and SPR strains had substitutions within the NF-κB and the γ-IRE transcription binding factor, respectively.
Keywords: nitric oxide; mice; genetic factor; sequencing
Phylogenetics of Freshwater Black Basses (Centrarchidae: Micropterus) Inferred from Restriction Endonuclease Analysis of Mitochondrial DNA by Ronald L. Johnson; James B. Magee; Timothy A. Hodge (pp. 395-406).
Geographic isolation and habitat specialization has aided in the evolution and genetic integrity of the micropterid bass species of North America. Members of the genus Micropterus form a close natural unit with little morphologic and meristic variation. Our goals were to measure the genetic characteristics of and distances between six black bass species by using mitochondrial DNA analysis. Mitochondrial DNA restriction fragment length polymorphisms were examined in Guadalupe bass (M. treculi), largemouth bass (M. salmoides), shoal bass (M. cataractae), smallmouth bass (M. dolomieu), spotted bass (M. punctulatus), and Suwannee bass (M. notius), using 15 restriction endonucleases. The bluegill (Lepomis macrochirus) was used as an outgroup. The phylogeny inferred from Dollo parsimony cladistic analysis concurred with published results from allozyme analyses, yet it was inconsistent with published meristic analyses. Genetic distances between species ranged from 0.0659 to 0.2145, with the largemouth and Suwannee basses showing the greatest divergence from the other black basses. The Guadalupe, smallmouth, and spotted basses were most diverged from the bluegill. The black basses diverged over a broad time frame, with estimated black bass speciation occurring during late Miocene – early Pliocene (3.30–10.73 MYA).
Keywords: mitochondrial DNA; phylogenetics; Micropterus ; black basses
Specific Frequency Distribution of Erythrocytic X-Protein Alleles in Indigenous Sheep Populations in East Asia by Kenji Tsunoda; Keizo Sato (pp. 407-416).
The nonhemoglobin erythrocytic X-protein polymorphism consisting of two phenotypes called X-positive [X(+)] and X-negative [X(−)] was determined in 576 unrelated healthy native sheep of East Asia, using one-dimensional and horizontal starch gel electrophoresis. A striking difference in the frequency of the X allele coding dominantly for the X(+) type between the northern and southern populations of native East Asian sheep divided by the boundary of the Himalaya Mountains was seen (P < 0.0001). The X allele frequency ranged from 0 to 0.0438 with an average of 0.0323 in the northern population examined, consisting of the Bhyanglung, Baruwal, Yunnan, and Khalkhas sheep belonging to the Tibetan and Mongolian sheep groups. In contrast, the frequency of the same allele was in the range of 0.2037–0.4655 and the mean frequency was 0.2998 in the southern population tested, consisting of the Bengal, Kagi, Lampuchhre, Vietnamese, and Myanmar sheep, which belong to the Indian sheep group. This finding suggests that the X allele appears to be an Indian sheep marker and is potentially important in phylogenetic studies on native sheep populations, especially in East Asia.
Keywords: X-protein; genetic polymorphism; Asian domestic sheep; erythrocyte; phylogenetic gene marker
Mitochondrial Cytochrome b Gene Sequence Diversity in the Korean Hare, Lepus coreanus Thomas (Mammalia, Lagomorpha) by Hung Sun Koh; Tae Young Chun; Hye Sook Yoo; Ya-ping Zhang; Jinxing Wang; Minghai Zhang; Chun-hua Wu (pp. 417-429).
Partial sequences of the mitochondrial cytochrome b gene of the Korean hare (Lepus coreanus) were analyzed to determine the degree of genetic diversity. Nine haplotypes were observed, and the maximum Tamura–Nei nucleotide distance among them was 2.8%, indicating that genetic diversity of L. coreanus is moderate. In order to clarify the Korean hare's taxonomic status and relationship with the Manchurian hare (L. mandshuricus) and the Chinese hare (L. sinensis), these nine haplotypes of the Korean hare were compared with 13 haplotypes from five other species of eastern Asian Lepus including L. mandshuricus and L. sinensis. The Korean hare was distinct in its cytochrome b gene, and it is confirmed that L. coreanus is a valid species, as noted by Jones and Johnson (1965, Univ. Kansas Publ. (Mus. Nat. Hist.) 16:357). Further analyses of mtDNA cytochrome b gene with additional specimens of L. coreanus from North Korea and other species of Lepus from eastern Asia are needed to clarify the taxonomic status of the divergent mtDNA clades of L. mandshuricus and L. sinensis.
Keywords: systematics; mtDNA cytochrome b gene; the Korean hare; Lepus coreanus