Biomedical subjects

D K Chowdhuri

Publications and source records attributed to D K Chowdhuri.

7 recordsLinked to original sources

PubMed2002

Toxicity of argemone oil: effect on hsp70 expression and tissue damage in transgenic Drosophila melanogaster (hsp70-lacZ) Bg9.

The effect of argemone oil on hsp70 expression and tissue damage was investigated by studying beta-galactosidase activity, Western blotting and hybridization, and trypan blue staining in the larval tissues of transgenic Drosophila melanogaster (hsp70-lacZ)Bg9. Different concentrations of argemone oil were mixed with food and third-instar larvae were allowed to feed on them for different time intervals (2, 4, 24, and 48 h). Argemone oil was found to induce hsp70 even in the lowest concentration of the adulterant while maximum tissue damage was observed in the higher two treatment groups. Malpighian tubules and midgut tissue reflected maximum damage as evidenced by both high beta-galactosidase activity and trypan blue staining in these tissues. A prior temperature shock treatment to the larvae was enough to protect the larvae from argemone oil-induced tissue damage as evidenced by little or no trypan blue staining. The present study suggests the cytotoxic potential of argemone oil and further strengthens the evidence for the use of hsp70 as a biomarker in risk assessment.

Animals↗

PubMed2001

Effect of three chlorinated pesticides on hsromega stress gene in transgenic Drosophila melanogaster.

Expression of hsromega stress gene in the third-instar larvae of 951-lacZ2 (hsromega-lacZ having-844pb sequence) and 498-lacZ1 (hrsomega-lacZ having -498bp sequence) strains of Drosophila melanogaster at LC(50) and lower dietary concentrations of hexachlorocyclohexane (HCH) pentachlorophenol (PCP), and endosulfan was examined in relation to larval mortality by beta galactosidase activity, vital dye staining, and salivary gland polytene chromosome puffing. Our results showed that both HCH and PCP at lower concentrations evoked strong hsromega stress gene expression in the larval tissues while endosulfan did not. On the other hand, puffing data revealed that endosulfan at lower doses, induced well-developed puff at the resident site (93D) of the hsromega gene but the transgenic sites (30B in 951-lacZ2 and 44B in 498-lacZ1 strain) did not show any well-developed puff. Regression in hsromega stress gene expression in 951-lacZ2 strain at LC(50) concentrations of HCH and PCP after 48 h was concurrent with extensive tissue damage as evident by trypan blue staining. Similarly, strong hsromega expression was accompanied by insignificant trypan blue staining in the larval tissues of this strain after shorter duration of exposure (2-12 h) to these toxicants. Although endosulfan under similar experimental condition did not induce hsromega, strong trypan blue staining indicated extensive tissue damage after 48 h of exposure. The present study suggests that all the three toxicants pose cytotoxic potential to Drosophila. While protective role of this stress gene was evident at the initial stages of exposure, extensive tissue damage in the later stages of intoxication accompanied by autorepression of hsromega led to larval mortality. The study further suggests that -844bp upstream sequence of the gene is adequate for hsromega inducibility against HCH and PCP but not for endosulfan for which responsive elements may be searched further upstream.

Animals↗

PubMed2001

Effect of lead and chromium on nucleic acid and protein synthesis during sperm-zona binding in mice.

Lead and chromium are ubiquitous environmental pollutants and their effects on reproductive physiology as shown by animal experiments and human studies is well documented. The present study was conducted to ascertain the role of these metals on gamete physiology during the sperm-zona binding process, Superovulated ova and capacitated sperm from BALB/c mice were exposed to lead (0.0, 0.2, 0. 5, 1.0 and 2.0 microg/ml) or chromium (0.0, 5.0, 10.0 and 20.0 microg/ml) for 2 h in the culture medium. The sperm that became attached to the ova in the presence of these metals were scored. Synthesis of DNA, RNA and protein was assessed during this process by labelling the cells with [3H]thymidine (20 microCi/ml), [3H]uridine (50 microCi/ml) and [35S]methionine (10 microCi/ml) in the culture medium after exposure to the metals for 2 h. Our studies show a significant dose-dependent decrease in the number of sperm attaching to the ova in both exposed groups along with a decrease in the incorporation of radiolabelled thymidine, uridine and methionine. The results indicate that DNA, RNA and protein synthesis under sperm-zona binding conditions are affected by the presence of these two metals. The physiology of the gametes is altered resulting in a low frequency of sperm attachment to the ova, which in turn leads to a risk of reproductive failure.

Animals↗

PubMed2001

Internet: a major resource for toxicologists.

Use of the Internet in developing countries is now growing faster. Internet has created a new conduit not only for communication but also in the access, sharing and exchange of information among scientists. The Internet is now viewed as the world's biggest library where retrieval of scientific literature and other information resources are possible within seconds. Large volumes of toxicological information resources are available on the Internet. This review outlines some sites that may be of great importance and useful to the toxicologist.

Internet↗

PubMed1998

Effect of hexachlorocyclohexane on hsp26 expression in transgenic Drosophila melanogaster.

Hexachlorocyclohexane (HCH) at different concentrations (0.5 to 5.0 ng/ml) mixed with food was fed to third instar larvae of hsp26-lacZ transgenic Drosophila for 2 hr and hsp26 gene expression was examined by beta-galactosidase staining. Puffing in salivary gland polytene chromosomes was also studied. Brain and midgut of larvae showed dark blue staining at 2.0 and 5.0 ng/ml of HCH. Absence of induced puffing at 67B and 84D in the salivary gland polytene chromosomes indicated that these glands are not affected. The study suggests presence of the vulnerable sites in larvae to the higher concentrations of HCH.

Animals↗

PubMed1997

Lead-induced changes in ovarian follicular development and maturation in mice.

Lead, a potent reproductive toxicant in humans and experimental animals, was used to detect the morphological basis of ovarian toxicity in mice by counting the various stages of follicular development using different doses of lead acetate (0, 2, 4 or 8 mg/kg/d) for 60 d (5 d/wk) by oral gavage. Our results revealed that while small and medium follicles were significantly affected even at the lowest dose (2 mg), the large follicles were affected mostly at the highest dose. Atresia even in the medium follicles reflected the extent of damage caused by lead. These findings correlated well with increased blood lead levels. Therefore, lead seems to affect the follicular development and maturation, if mice are, exposed to sufficiently high concentrations of metal through the oral route.

Animals↗

PubMed1990

Mutations affecting beta-alanine metabolism influence inducibility of the 93D puff by heat shock in Drosophila melanogaster.

Effect of mutations at the ebony or black locus on induction of heat shock puffs in polytene nuclei of salivary glands of Drosophila melanogaster larvae were examined by [3H]uridine autoradiography. The levels of beta-alanine in the body are known to be increased by mutation at the ebony locus but decreased by mutation at the black locus. The presence of mutant allele/s at either locus in the homo- or heterozygous condition prevented induction of the 93D puff by heat shock. Elimination of the mutant allele at the ebony or black locus by recombination or by reversion of a P element insertion mutant allele of ebony restored the heat shock inducibility of the 93D puff. In vivo or in vitro administration of excess beta-alanine to salivary glands of wild-type larvae also resulted in the 93D site being refractory to heat shock induction. In agreement with earlier results, non-induction of the 93D puff during heat shock due to the beta-alanine effect was accompanied by unequal puffing of the 87A and 87C loci. The selective inducibility of the 93D puff by benzamide was not affected by ebony or black mutations or by excess beta-alanine in wild-type larvae.

Alleles↗