Study of inheritance of diabetes mellitus in Western Indian population by pedigree analysis.

OBJECTIVES: To study the inheritance pattern of diabetes mellitus in Western Indian population by analysing the pedigree of diabetes patients. METHODS: 3,921 individuals from 300 families were interviewed for family history in this study, out of which 770 were diabetic individuals. Statistical analysis of the data was carried out using T-test and Chi-square test. RESULTS: 37% cases of Type 1 DM and 58% cases of Type 2 DM showed family history of the disease. Of the cases showing family history for diabetes, 92% in case of Type 1 DM and 59% in case of Type 2 DM showed family history of Type 2 DM with a decrease in age of onset in the successive generations. Both the parents, when diabetic conferred equal risk of inheriting diabetes in offspring. The sex ratio of offspring suffering from diabetes was not influenced when only one of the parents was diabetic. However it was observed that the male offspring were highly susceptible when both parents were diabetic (Chi-square value=4.55 with 1 d.f.). The age of onset of diabetes did not show significant correlation with whether one or both the parents were diabetic. However, it was noteworthy that in case of familial history of diabetes there was a decrease in the age of onset in successive generations. CONCLUSION: This study suggests that family history of diabetes results in predisposition to early onset of the disease in successive generations and a cluster of genes involved in Type 2 DM may show a parental effect for predisposition to Type 1 DM in the offspring in this set of Indian population.

Enhanced esterase activity in salivary gland and midgut of Aedes aegypti mosquito infected with dengue-2 virus.

Mosquitoes were infected by intrathoracic inoculation. About 95% head squashes were positive for dengue virus antigen on the 15th post infection day (PID). Esterase activity was determined in the homogenates prepared from the salivary glands and midguts on different PIDs of dengue virus inoculated and control mosquitoes showed that it was consistently higher in the virus-infected batches.

Highly-substrate active isoenzyme acetylcholinesterase-II, in rosy eye mutant of Aedes aegypti mosquito.

Insecticide bioassays were carried out on larvae and adults of rosy eye mutant and wildtype strains of A. aegypti. Both the strains were equally susceptible to DDT, malathion and deltamethrin. Biochemical assays showed an increase in acetylcholinesterase enzyme (AChE) activity in all the stages of mutant strain with both the substrates i.e. acetylthiocholine iodide and S-butyrylthiocholine iodide. However, there was no difference in the percent inhibition of enzyme activity with propoxur in these two strains. Polyacrylamide gel electrophoresis performed in native conditions on the homogenates of adults of rosy eye mosquitoes showed that AChE-II allele was highly active with the substrate acetylthiocholine iodide as compared to wildtype strain. Frequency of the highly active AChE-II allele in the mutant strain was about 68%, whereas it was about 5% in the wildtype strain.

Characterization of MboI repeat DNA sequence of Anopheles stephensi.

MboI repeat fragment of mosquito Anopheles stephensi has been isolated by molecular cloning. The restriction map and entire nucleotide sequence of the 433bp insert has been determined. Hybridization of this repeat DNA with restriction enzyme digest of mosquito DNA does not show an interspersed pattern but suggests that this repeat may be tandemly repeated at one major site and a few minor sites in the genome of Anopheles stephensi. The hybridization pattern also indicates that this repeat family comprises of many similar but non-identical sequences. An open reading frame encoding 66 amino acids with an initiation and two tandem termination codons has been identified. This putative 66 amino acid polypeptide sequence has significant homology to a small region of RNA tumour viral envelope protein.