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Biochemical Genetics (v.38, #9-10)

Genetic Distances Among North American, British, and West African House Fly Populations (Musca domestica L.) by E. S. Krafsur; N. L. Bryant; J. G. Marquez; N. T. Griffiths (pp. 275-284).

Allozyme and mitochondrial gene diversities were estimated in house flies, Musca domestica L. (Diptera: Muscidae), sampled in Iowa, USA; Berkshire, England; and Kudang, The Gambia. Comparison of genomic allele frequencies among the three populations indicated small differences between the English and American samples but very large distances between English or American and the African. The F _ST statistic was 0.65 ± 0.09 for allozymes. Pairwise F _ST was 0.14 between the English and the American samples; F _ST was 0.65 between the African population and the English and American. Mitochondrial variation in the same flies was assessed by SSCP methods which revealed nine haplotypes, none of which were shared in common. F _ST was 0.637 for the mitochondrial haplotypes. The research indicates greatly restricted gene flow between Africa and the temperate regions.

Keywords: Musca domestica ; allozymes; mtDNA; gene flow; population genetics

Allozyme Variation in Busycon Whelks (Gastropoda: Melongenidae) by Stewart H. Berlocher (pp. 285-296).

Large Busycon whelks are used in physiological research and are key predators in shallow water marine communities in eastern North America. Allozyme analysis of 16 loci in Busycon carica (knobbed whelk), B. sinistrum (left-handed or lightning whelk), and the closely related outgroup Busycotypus spiratum (pear whelk) was performed. Striking differences in within-species genetic differentiation were observed. Geographic variation in B. carica is moderate (F _ST = 0.051). In B. sinistrum, however, F _ST is 0.625, suggesting the existence of either highly distinct subspecies or unresolved species. The pattern of genetic variation in B. sinistrum may be congruent with that in other taxa that have experienced Gulf-Atlantic and eastern-western Gulf vicariance events. The data are compatible with an evolutionary rate of 0.046 Nei D million years.

Keywords: Busycon ; molluscan systematics; molecular systematics; allozymes; Gulf–Atlantic vicariance

Phenobarbital Induction of Aldehyde Dehydrogenase Type 2 mRNA in Mouse Liver: A Candidate Region on Chromosome 7 for a Putative Regulatory Gene by Nathalie Marc; Alain Fautrel; Marie Damon; Andr´e Guillouzo; Laurent Corcos (pp. 297-308).

Phenobarbital (PB) strongly induces in the liver the expression of many genes encoding detoxication enzymes, such as the aldehyde dehydrogenase type 2 in the mouse (Aldh2). With the aim of identifying genes involved in this response, we have undertaken an approach based on a genetic analysis in mice. In a previous report, the genetic analysis of both the C57BL/6J (B6) × DBA/2J (D2) F₁ and the (F₁ × F₁) F₂ led us to the hypothesis that Aldh2 responsiveness to PB was under the control of one major locus independent of the structural gene. In the present study, the genetic analysis of the inducibility by PB of Aldh2 in the backcross population B6D2F1 × D2 has allowed us to confirm the involvement of a major regulatory gene in this mechanism. By searching for genetic linkage between this locus and a series of microsatellites DNA markers, we obtained indicative evidence for a region on chromosome 7, which may carry this gene.

Keywords: liver; mouse; phenobarbital; aldehyde dehydrogenase; chromosome 7

Molecular Characterization of a Parasitic Tapeworm (Ligula) Based on DNA Sequences from Formalin-Fixed Specimens by Jingjing Li; Xianghua Liao; Hong Yang (pp. 309-322).

Museum specimens of Ligula (Pseudophyllidea, Ligulidae), a fish parasite tapeworm, that have been preserved in ethanol or fixed permanently in formalin up to 24 years were used for DNA extraction and molecular characterization. DNA was amplified via PCR from samples collected from different fish hosts that lived in both salt and fresh water bodies in the Chinese Qinghai–Tibet Plateau, Russia, and England. Phylogenetic analyses based on partial nucleotide sequences of the 5"-end of nuclear 28S rRNA gene and the mitochondrial cytochrome c oxidase subunit I (COI) gene support the morphologically based taxonomy that groups the Chinese Ligula within the same species as their Europe counterpart: Lingula intestinalis. No nucleotide variation was detected in either the 28S rRNA gene or the COI gene among the seven plerocercoid samples, suggesting a considerable genetic homogeneity among Ligula from different regions. Our results show that geographic isolation, affinity of hosts, and host habitats are not reliable taxonomic criteria for Ligula classification. Our data also indicate a low genetic diversity in the Ligula prevalent in China and in Europe. Our experiments demonstrate that endogenous DNA from specimens that were subjected to permanent formalin fixation can be routinely amplified from parasitic tapeworms, suggesting that fixation time in formalin may not be a critical factor affecting DNA degradation in such museum specimens.

Keywords: ancient DNA; parasitic tapeworm; formalin specimen; Ligula

Sequence Heteroplasmy of D-Loop and rRNA Coding Regions in Mitochondrial DNA from Holstein Cows of Independent Maternal Lineages by Jianming Wu; Renotta K. Smith; A. E. Freeman; Donald C. Beitz; Ben T. McDaniel; Gary L. Lindberg (pp. 323-336).

A mitochondrial DNA (mtDNA) fragment containing the D-loop, phenylalanine tRNA, valine tRNA, and 12S and 16 rRNA genes was cloned and sequenced from 36 cows of 18 maternal lineages to identify the polymorphic sites within those regions and to detect the existence of heteroplasmic mtDNA in cows. Seventeen variable sites were observed within the D-loop and rRNA coding regions of bovine mtDNA within a 2.5-kb span. The hypervariable sites in the D-loop and rRNA coding regions were identified at nucleotide positions 169, 216, and 1594. Heteroplasmic mtDNA (variable mtDNA within a tissue) existed extensively in cows and was detected within the above regions in 11 of 36 cows sequenced. The insertion, deletion, and nucleotide transversion polymorphisms were found only in homopolymer regions. Heteroplasmy was observed frequently and seemingly is persistent in cattle. Though heteroplasmy was demonstrated, most lineages and mtDNA sites showed no heteroplasmy.

Keywords: mitochondrial DNA; mitochondrial inheritance; Holstein cows; heteroplasmy

Mapping of Mouse α1(XIII) Collagen to Chromosome 10 and Its Exclusion as a kd Candidate Gene by Michal Mrug; John Stockwin; Rudolf P. W¨uthrich; David L. Gasser; Lisa M. Guay-Woodford (pp. 337-340).

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Biochemical Genetics (v.38, #9-10)

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Biochemical Genetics (v.38, #9-10)