H.S. Yong

Protein variation and systematics of three subgenera of Malayan rats (Rodentia: Muridae, Genus Rattus Fischer)

1. Nine erythrocyte proteins coded by a separate locus each were analysed in and among seven Malayan species of Rattus belonging to three subgenera. 2. Electrophoretic data obtained confirm the specific status of the seven taxa and divide the seven species into three groups which correspond with Ellermans (1949) subgenera Stenomys, Maxomys and Leopoldamys. 3. A comparative study together with 11 other species of Malayan Rattus previously analysed show that, with few exceptions, the overall relationships among the 18 species based on electrophoretic data correspond well with conclusions based on morphological evidence. 4. Malayan species of Rattus are relatively very diverse genetically (S = 0.27, range 0.01-0.94).

Allozyme variation in the melon fly Dacus cucurbitae (Insecta: Diptera: Tephritidae) from peninsular Malaysia

Abstract 1. 1. Population samples of Dacus cucurbitae from four localities in Peninsular Malaysia were analyzed for 5–12 gene-enzyme systems comprising 7–14 loci. 2. 2. Six loci, EST-F, HK-2, IDH, aMDH, PGM and PGD, were polymorphic. 3. 3. Hexokinase-2, isocitrate dehydrogenase, anodal malate dehydrogenase and phosphogluconate dehydrogenase were represented by two alleles each, while esterase-F and phosphoglucomutase were represented by three alleles each. 4. 4. Phosphoglucomutase showed greater variability than the other polymorphic loci, while phosphogluconate dehydrogenase was the least variable. 5. 5. The proportion of polymorphic loci ranged from 0.21 to 0.57, while the mean heterozygosity ranged from 0.09 to 0.23.

Low allozyme variability in Bactrocera albistrigata (Insecta: Diptera: Tephritidae) from Peninsular Malaysia

1. Population samples of Bactrocera albistrigata from Peninsular Malaysia were analyzed for 12 to 14 gene-enzyme systems comprising 15-18 loci. 2. Three loci, aMDH, PGD and PGM, were polymorphic. 3. Anodal malate dehydrogenase and phosphogluconate dehydrogenase were represented by two alleles each, while phosphoglucomutase was represented by three alleles. 4. Phosphoglucomutase had a higher heterozygosity than anodal malate dehydrogenase and phosphogluconate dehydrogenase. 5. B. albistrigata was characterized by low genetic variability, as measured by the proportion of polymorphic loci and heterozygosity.

Allozyme variation in the artocarpus fruit fly Dacus umbrosus (Insecta: Tephritidae) from peninsular Malaysia

1. 1. Population samples of Dacus umbrosus from 4 localities in Peninsular Malaysia were analysed for 13 gene-enzyme systems comprising 18 loci. 2. 2. Four loci-HK-1, IDH, EST-D1 and MDH-2-were polymorphic. 3. 3. All four polymorphic loci were represented by two alleles each. 4. 4. D. umbrosus was characterized by low genetic variability, as measured by proportion of polymorphic loci and heterozygosity.

Phosphoglucomutase polymorphism in the oriental fruit fly, Dacus dorsalis (Diptera, Tephritidae) from Peninsular Malaysia

Seven natural populations of Dacus dorsalis were analysed for phosphoglucomutase by means of horizontal starch-gel electrophoresis. The electrophoretic phenotypes were governed by four codominant Pgm alleles. The commonest allele in all the seven population samples was PgmB which encoded an electrophoretic band with intermediate mobility. The distributions of PGM phenotype were in accordance with Hardy-Weinberg expectations. There was geographic variation in the distribution of Pgm alleles.

Isocitrate dehydrogenase and phosphogluconate dehydrogenase polymorphism in the oriental fruit fly, Dacus dorsalis (Insecta, Tephritidae), from Peninsular Malaysia

Abstract 1. Six natural populations of Dacus dorsalis were analysed for isocitrate dehydrogenase and phosphogluconate dehydrogenase by means of horizontal starch-gel electrophoresis. 2. Isocitrate dehydrogenase phenotypes were governed by three codominant alleles, while phosphogluconate dehydrogenase phenotypes were governed by four alleles. 3. The commonest Idh and Pgd alleles encoded an electrophoretic band with intermediate mobility. 4. Isocitrate dehydrogenase had lower heterozygosity than phosphogluconate dehydrogenase. 5. There was geographic variation in the distribution of Pgd alleles.

Biochemical genetic relationship in three taxa of the malaria mosquito Anopheles balabacensis complex

Three taxa of the malaria mosquito Anopheles balabacensis complex representing three geographical regions (Thailand, Peninsular Malaysia and Sabah) in Southeast Asia, were analysed for genetic variation at 15 gene-enzyme systems. The Sabah taxon was monomorphic for all the 15 gene-enzyme systems. Only two gene-enzyme systems (esterase and glucose phosphate isomerase) were variable in the Thailand and Peninsular Malaysia taxa. The average heterozygosity or gene diversity was 0.007 for the Thailand taxon and 0.028 for the Peninsular Malaysia (Perlis) taxon. There were no unique gene-enzyme markers in the three taxa studied. The average values of genetic identities (0.933-0.997) and genetic distances (0.003-0.069) indicate that these three taxa are of subspecific status.

Variability of malate dehydrogenase isozymes in the oriental fruit fly Dacus dorsalis (Insecta: Tephritidae) from Peninsular Malaysia

1. 1. Sixteen population samples of Dacus dorsalis from 10 localities in Peninsular Malaysia were analysed for malate dehydrogenase by means of horizontal starch-gel electrophoresis. 2. 2. Two distinct zones (loci) of MDH activity were present. 3. 3. Both Mdh loci were polymorphic. The MDH-1 electromorphs were governed by three codominant alleles, while the MDH-2 electromorphs were governed by eight alleles. 4. 4. Mdh-1100 and Mdh-2100 were the commonest alleles in all the population samples. They encoded an electrophoretic band with intermediate mobility. 5. 5. Both Mdh loci showed low variability.

Allozyme variation in a dimeric esterase of the oriental fruit fly, Dacus dorsalis (insecta: tephritidae), from peninsular malaysia

Abstract 1. 1. Seven natural populations of Dacus dorsalis were analyzed for a dimeric esterase by means of horizontal starch-gel electrophoresis. 2. 2. The electrophoretic phenotypes were governed by nine codominant Est-D alleles. 3. 3. The commonest allele in all seven population samples was Est-D 100 which encoded an electrophoretic band with intermediate mobility. 4. 4. The distribution of EST-D phenotypes were in accordance with Hardy-Weinberg expectations. 5. 5. There was no geographic variation in the distribution of Est-D alleles.

Glischropus tylopus, the first known old-world bat with an X-autosome translocation

Glischropus tylopus shows an X-autosome translocation in which a small acrocentric chromosome has been transferred to the X. The diploid number is 30 for the females and 31 for the males. RBG banding shows that in the late replicating X of the female only the original X replicates late, the autosomal part replicates early, showing the same pattern as the corresponding autosomal ‘Y2’ of the male. In the X chromosome, a heterochromatic band separates the autosomal from the gonosomal sequences.