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Biochemical Genetics (v.35, #1-2)

Genetic Variation at Structural Loci in the Glossina morsitans Species Group by E. S. Krafsur; N. Griffiths (pp. 1-11).

Gene diversity was investigated in four taxa of tsetse flies (Diptera: Glossinidae) including Glossina morsitans morsitans, G. m. centralis, G. swynnertoni, and G. pallidipes. Histochemical tests were performed for 35–46 isozymes. Polymorphic loci were 20% in G. morsitans morsitans, 32% in G. m. centralis, 17.6% in G. swynnertoni, and 26% in G. pallidipes. Mean heterozygosities among all loci were 6.6% in G. morsitans morsitans, 6.0% in G. m. centralis, 7.1% in G. swynnertoni, and 6.8% in G. pallidipes. Allozyme gene diversities were considerably less than those reported for many Diptera. The low gene diversities are probably related to small effective population sizes.

Keywords: Glossina morsitans species group; tsetse flies; isozymes; gene diversity

Genetic Diversity and Divergence in Chinese Yak (Bos grunniens) Populations Inferred from Blood Protein Electrophoresis by Zheng-Chao Tu; Ya-Ping Zhang; Huai Qiu (pp. 13-16).

In 6 Chinese yak (Bos. Grunniens) populations including 177 yaks, 34 blood protein loci were studied by horizontal starch gel electrophoresis, four of these loci (AKP, ALB, LDH-1, TF) were found to be polymorphic. The percentage of polymorphic loci(P) is 0.118, the mean individual heterozygosity(H) is 0.015, which means a low level of genetic diversity in the whole Chinese yak population. The coefficient of gene differentiation (G _ST ) is 0.0625, which indicated an almost-indistinguishable divergence among different populations at the level of blood protein electrophoresis.

Keywords: Chinese yak; blood protein electrophoresis; Bos grunniens ; genetic diversity; genetic divergence

Biochemistry of Esterases Associated with Organophosphate Resistance in Lucilia cuprina with Comparisons to Putative Orthologues in Other Diptera by Peter M. Campbell; Josephine F. Trott; Charles Claudianos; Kerrie-Ann Smyth; Robyn J. Russell; John G. Oakeshott (pp. 17-40).

Esterase activities associated with organophosphate insecticide resistance in the Australian sheep blowfly, Lucilia cuprina, are compared with similar activities in other Diptera. The enzymes making the major contribution to methyl butyrate hydrolysis (“ali-esterase”) in L. cuprina, M. domestica, and D. melanogaster comigrate during electrophoresis. The enzymes in L. cuprina and D. melanogaster correspond to the naphthyl acetate hydrolyzing E3 and EST23 isozymes of those species. These and previously published data suggest that the ali-esterases of all three species are orthologous. Strains of L. cuprina fall into four groups on the basis of quantitative determinations of their ali-estesterase, OP hydrolase, and malathion carboxylesterase activities and these groups correspond to their status with respect to two types of OP resistance. Strains susceptible to OPs have high ali-esterase, low OP hydrolase, and intermediate MCE activities; those resistant to malathion but not diazinon have low ali-esterase, intermediate OP hydrolase, and high MCE activities; those resistant to diazinon but not malathion have low ali-esterase, high OP hydrolase, and low MCE activities; those resistant to both OPs have low ali-esterase, high OP hydrolase, and high MCE activities. The correlated changes among the three biochemical and two resistance phenotypes suggest that they are all properties of one gene/enzyme system; three major allelic variants of that system explain OP susceptibility and the two types of OP resistance. Models are proposed to explain the joint contribution of OP hydrolase and MCE activities to malathion resistance and the invariant association of low ali-esterase and elevated OP hydrolase activities in either type of resistance.

Keywords: organophosphorus insecticide resistance; esterase; Lucilia cuprina ; Musca domestica

Genetic Variants Affecting Phenoloxidase Activity in Drosophila melanogaster by Nobuhiko Asada (pp. 41-49).

In Drosophila melanogaster, two new variants affecting the activity of phenoloxidase were found in natural populations at Gomel in Belorussia and at Krasnodar in Russia. Prophenoloxidases, A ₁ and A ₃ , in these variants had the same mobilities on native electrophoresis as the wild type. However, enzymatic activities in their activated states were much lower than in the wild type, whereas the existence of prophenoloxidase proteins was demonstrated. Egg-to-adult and relative viabilities in the variants did not decrease at temperatures between 18 and 29°C. Genetic analyses indicated that the genes showing the phenotype of variants are new alleles of Mox and Dox-3 on the second chromosome.

Keywords: Drosophila melanogaster ; null activity; phenoloxidase

Comparison of the Subcellular Distribution of the Messages Encoding PLP and DM-20 by Neil R. McEwan (pp. 51-58).

Oligonucleotides provide a means to differentiate between closely related mRNAs. Here in situ hybridization is performed using oligonucleotide probes to determine the subcellular distribution of two differential splicing products of a single gene. It is demonstrated here that the subcellular distributions of PLP and DM-20 messages in Oligodendrocytes are quite different, despite being transcripts of a single gene.

Keywords: proteolipid protein; DM-20; mRNA; in situ hybridization; oligonucleotides

The Glycophorin A Gene Family in Gorillas: Structure, Expression, and Comparison with the Human and Chimpanzee Homologues by Shen-Si Xie; Cheng-Han Huang; Marion E. Reid; Antoine Blancher; Olga O. Blumenfeld (pp. 59-76).

Homologues of MN blood group antigens, encoded by members of the glycophorin A (GPA) gene family, are expressed in man, anthropoid apes, and some species of Old World monkeys. Previous studies had shown that a three-gene framework, most closely related to that in man, is present in the chimpanzee. Here we report the genomic structure, transcript map, and protein expression of the GYPA locus in gorillas. Compared to the corresponding human and chimpanzee homologues, gorilla GPA, GPB, and GPB/E genes each showed a high degree of sequence identity, with the same exon-intron organization. However, the expression of exons III, IV, or V encoding the extracellular or membrane domains of homologous glycophorins varied among the three species. Gorilla GPA and GPB/E genes were unique in that the former occurred in two allelic forms with or without the expression of exon III, whereas the latter contained one (ψ exon III) instead of two silenced exons (ψ exons III and IV). Differences from human but not chimpanzee GPA also included the presence of a hybrid M/N epitope and the absence of the sequon for N-glycosylation. Owing to the retention of a functional exon III, gorilla GPB was more similar to chimpanzee GPB than human GPB. A transspecies allele was identified in the gorilla that gave rise to the Henshaw (He)-like antigen similar to that found in man. These results provide further insight into the model for evolution of the GPA gene family, indicating that the mechanisms underlying inter- and intraspecific polymorphism of glycophorins could predate the divergence of gorillas as the consequence of gene duplication and diversification.

Keywords: glycophorins; gorilla; evolution; gene family; gene expression

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Biochemical Genetics (v.35, #1-2)

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Biochemical Genetics (v.35, #1-2)