Gamma radiation induced changes in expression of heat shock proteins (Hsc70 and Hsp83) in the dengue vector Aedes aegypti (L.)

We aimed to assess the effect of gamma radiation on the expression of heat shock proteins Hsc70 and Hsp83 in Aedes aegypti. Adult males were irradiated with 50Gy of gamma radiation, and changes in the expression of proteins in SDS-PAGE gel bands corresponding to molecular weights ~60–75kDa and ~80–95kDa were analyzed at two different time points 6 and 12-hour post-irradiation, using a temporal mass spectrometry based semi-quantitative analysis. A 2-3-fold increase was observed in both proteins Hsc70 and Hsp83, at both time points. In addition, the experiment also revealed the overexpression of several other molecules such as Arginine Kinase - known to be upregulated in certain insects during stress, Esterase B1- implicated in insecticide resistance, and also down-regulation of the 26S proteasome non-ATPase regulatory subunit 1 and ubiquitin-activating enzyme E1 - both known to be involved in ubiquitin-mediated protein degradation. The results taken together with existing data on Hsp83 and Hsc70, indicate that these proteins may enhance the survival of Ae. aegypti following gamma radiation and could serve as molecular markers for the detection of radiation-induced stress.

The genetics of green thorax, a new larval colour mutant, non-linked with ruby-eye locus in the malaria mosquito, Anopheles stephensi Liston.

Background & objectives: Anopheles stephensi, an important vector of malaria continues to be distributed widely in the Indian subcontinent. The natural vigour of the species combined with its new tolerance, indeed resistance to insecticides has made it obligatory that we look for control methods involving genetic manipulation. Hence, there is an immediate need for greater understanding of the genetics of this vector species. One of the requirements for such genetic studies is the establishment of naturally occurring mutants, establishment of the genetic basis for the same and use of such mutants in the genetic transformation studies and other genetic control programme(s). This paper describes the isolation and genetic studies of a larval colour mutant, green thorax (gt), and linkage studies involving another autosomal recessive mutant ruby-eye (ru) in An. stephensi. Methods: After the initial discovery, the mutant green thorax was crossed inter se and pure homozygous stock of the mutant was established. The stock of the mutant ruby-eye, which has been maintained as a pure stock in the laboratory. Crosses were made between the wild type and mutant, green thorax to determine the mode of inheritance of green thorax. For linkage studies, crosses were made between the mutant green thorax and another autosomal recessive mutant ruby-eye. The percentage cross-over was calculated for the genes linkage relationship for gt and gt ru. Results: Results of crosses between mutant and wild type showed that the inheritance of green thorax (gt) in An. stephensi is monofactorial in nature. The gt allele is recessive to wild type and is autosomal. The linkage studies showed no linkage between ru and gt. Interpretation & conclusion: The mutant gt represents an excellent marker for An. stephensi as it is expressed in late III instar stage of larvae and is prominent in IV instar and pupal stages with complete penetrance and high viability. The said mutant could be easily identified without the aid of a microscope. This mutant can be used extensively to conduct basic and applied research. The mutant has been maintained in two large cages in our laboratory.

Dark larva a new autosomal larval colour mutant in the malaria mosquito, Anopheles stephensi Liston.

Anopheles stephensi is an important urban malaria vector, which is widely distributed throughout the Indian subcontinent. The said vector species has developed resistance to various insecticides and therefore, it is desirable to develop alternative strategies including genetic methods for its control. One of the requirements for such strategy is to establish morphological mutants and to establish the genetic basis of the same. Such mutant markers could be used in the construction of genetically modified strain/s in the genetic control programme of An. stephensi. The dark colour expresses in all larval stages and pupae with full penetarence and uniform expression in both the sexes. The viability of the mutant is as good as the wild type. The genetic studies of the dark larva revealed that the gene da is mono-factorial, autosomal and recessive to the wild type. The gene da is an excellent marker for An. stephensi.

Giant lesions in histoid leprosy--an unusual presentation.

A forty-year-old man presented with multiple, asymptomatic, raised lesions of one-year duration. Well-defined, non-tender papules and nodules were seen on the normal looking skin. Few giant lesions were seen over the lower legs and feet. Diffuse infiltration of the face and ears was present. Bilateral ulnar, radial cutaneous, sural and right superficial peroneal nerves were thickened. Slit-skin smear from a nodule had a BI of 6+. Biopsy showed features of histoid leprosy. The lesions had developed de novo, without previous dapsone monotherapy.

An evaluation of clinical and histopathological status in paucibacillary leprosy patients after completion of fixed duration therapy.

The present study was carried out involving 25 patients with paucibacillary leprosy who attended the outpatient department of dermatology of Father Muller's Medical College Hospital during the period January 2001 to March 2002. All the patients were examined clinically and histopathologically at the beginning and at the end of six months of MDT and relevant data recorded. Clinicopathological correlation with histopathological classification before MDT was 72% and 68% at the end of MDT in our study. At the end of treatment 4 (16%) cases were clinically active and 8 (32%) were histopathologlcally active. The study showed that active cases were significantly reduced as a result of MDT, both clinically and histopathologically. The histopathological activity that outlasts MDT may be due to the bacillary fragments that persist; but clinical activity coupled with histopathological activity seen in 2 patients at the end of 6 months of MDT was possibly an indicator of relapse and these patients and similar others need to be followed up for a longer duration. In this study, resolution of granuloma and clinical activity after completion of MDT were assessed.

Ruby-eye, a new autosomal mutant in the malaria mosquito, Anopheles stephensi Liston.

BACKGROUND & OBJECTIVES: Anopheles stephensi, an important vector of malaria continues to be distributed widely in the Indian subcontinent. This vector species has developed resistance for various insecticides. Therefore, it is desirable to develop alternate strategy, which does not involve resistance. In order to develop such strategy, it is mandatory that genetic studies of concerned vector species should be established. This paper describes the isolation and genetic studies of an eye colour mutant, ruby-eye (ru), and linkage studies involving another autosomal recessive mutant greyish brown larva (grb ru) in A. stephensi. METHODS: The stocks of mutants ruby-eye (ru), greyish brown (grb ru) and wild type mosquitoes were maintained in the laboratory. Crosses were made between the wild type and mutant to determine the mode of inheritance of ruby-eye. For linkage studies crosses were made between the mutant ruby-eye and another autosomal recessive mutant greyish brown larva. The percentage cross over was calculated for the genes linkage relationship for ru and grb ru. RESULTS: Results of crosses between mutant and wild type show that the inheritance of ruby-eye in A. stephensi is monofactorial in nature. The ru allele is recessive to wild type and is autosomal. The linkage studies showed no linkage between grb and ru. INTERPRETATION & CONCLUSION: The mutant ru represents an excellent marker for A. stephensi as it expresses in all the life stages with complete penetrance and high viability. This mutant can be used extensively to conduct basic and applied research.

Chromosomal translocations and inherited semisterility in the malaria vector Anopheles stephensi Liston.

Anopheles stephensi males were irradiated with 3500 rads of gamma rays at the rate of 140 rads/min to induce chromosomal aberrations. Seven reciprocal translocations were isolated, including four sex-linked and three autosomal. The presence of translocations were confirmed by cytological analysis.