Biomedical subjects

A Dutta-Gupta

Publications and source records attributed to A Dutta-Gupta.

12 recordsLinked to original sources

PubMed2006

Thiourea-induced thyroid hormone depletion impairs testicular recrudescence in the air-breathing catfish, Clarias gariepinus.

We used thiourea-induced thyroid hormone depletion as a strategy to understand the influence of thyroid hormones on testicular recrudescence of the air-breathing catfish, Clarias gariepinus. Treatment with 0.03% thiourea via immersion for 21 days induced hypothyroidism (thyroid hormone depletion) as evidenced by significantly reduced serum T(3) levels. Thiourea-treated males had narrowed seminiferous lobules with fewer spermatozoa in testis, very little or no secretory fluid, reduced protein and sialic acid levels in seminal vesicles when compared to controls. The histological changes were accompanied by reduction in serum and tissue levels of testosterone (T) and 11-ketotestosterone (11-KT), a potent male specific androgen in fish. Qualitative changes in the localization of catfish gonadotropin-releasing hormone (cfGnRH) and luteinizing hormone (LH, heterologous system) revealed a reduction in the distribution of immunoreactive neuronal cells and fibers in thyroid depleted fish. Interestingly, thiourea-withdrawal group showed physiological and histological signs of recovery after 21 days such as reappearance of spermatozoa and partial restoration of 11-KT and T levels. These data demonstrate that thyroid hormones play a significant role in testicular function of catfish. The mechanism of action includes modulating sex steroids either directly or through the hypothalamo (GnRH)-hypophyseal (LH) axis.

Animals↗

PubMed2006

Changes in cerebral membrane lipid composition and fluidity during thioacetamide-induced hepatic encephalopathy.

Lipids are an essential structural and functional component of cellular membranes. Changes in membrane lipid composition are known to affect the activities of many membrane-associated enzymes, endocytosis, exocytosis, membrane fusion and neurotransmitter uptake, and have been implicated in the pathophysiology of many neurodegenerative disorders. In the present study, we investigated changes in the lipid composition of membranes isolated from the cerebral cortex of rats treated with thioacetamide (TAA), a hepatotoxin that induces fulminant hepatic failure (FHF) and thereon hepatic encephalopathy (HE). HE refers to acute neuropsychiatric changes accompanying FHF. The estimation of membrane phospholipids, cholesterol and fatty acid content in cerebral cortex membranes from TAA-treated rats revealed a decrease in cholesterol, phosphatidylserine, sphingomyelin, a monounsaturated fatty acid, namely oleic acid, and the polyunsaturated fatty acids gamma-linolenic acid, decosa hexanoic acid and arachidonic acid compared with controls. Assessment of membrane fluidity with pyrene, 1,6-diphenyl-1,3,5-hexatriene and 1-[4-(trimethylammonio)phenyl]-6-phenyl-1,3,5-hexatriene revealed a decrease in the annular membrane fluidity, whereas the global fluidity was unaffected. The level of the thiobarbituric acid reactive species marker for lipid peroxidation also increased in membranes from TAA-treated rats, thereby indicating the prevalence of oxidative stress. Results from the present study demonstrate gross alterations in cerebral cortical membrane lipid composition and fluidity during TAA-induced HE, and their possible implications in the pathogenesis of this condition are also discussed.

Animals↗

PubMed2003

Complete sequence, expression and evolution of two members of the hexamerin protein family during the larval development of the rice moth, Corcyra cephalonica.

Three distinct types of storage hexamerins are expressed in the "last-instar" larvae of the rice moth, Corcyra cephalonica. A cDNA expression library was constructed from fat body-RNA and screened with a polyclonal antibody raised against purified hexamerin (SP2) of Corcyra cephalonica. Two slightly different "full-length" hexamerin cDNA clones (Hex2a and Hex2b) were isolated and sequenced. Both include open reading frames of 2109 bp which are translated into polypeptides of 703 amino acids with 92.5% identity. Signal peptides of 19 amino acids are present at the N-termini. The 684 amino acids native proteins have a high content of aryl groups (17.6%). According to both the criteria for amino acid composition and the phylogenetic analysis, Hex2a and Hex2b belong to the lepidopteran arylphorins. Northern blot studies revealed that the Hex2 genes are species- and tissue-specifically expressed in fat body cells of "last-instar" (= 5th) larvae.

Amino Acid Sequence↗

PubMed1998

Identification, characterization, immunocytochemical localization, and developmental changes in the activity of calcium/calmodulin-dependent protein kinase II in the CNS of Bombyx mori during postembryonic development.

In the present investigation, in vitro phosphorylation of CNS proteins of the silkworm Bombyx mori during the postembryonic development have been studied. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis and autoradiography of phosphorylated proteins revealed the presence of major phosphoproteins of 59/60 kDa. Based on molecular mass, calcium/calmodulin-dependent autophosphorylation, substrate specificity, KN-62 inhibition, apparent Km for ATP and syntide-2, these proteins were identified as calcium/calmodulin-dependent protein kinase II (CaM kinase II). Anti-rat CaM kinase II monoclonal antibody showed immunoreactivity with Bombyx CaM kinase II isoforms. This kinase showed a high degree of autophosphorylation in neural tissue. During postembryonic development of Bombyx, two distinct peaks of enzyme activity could be noticed, one at the late-larval and another at the late-pupal stage, which were associated with an increase in amount of the enzyme. These results suggested that the expression of CaM kinase II in the CNS of Bombyx was developmentally regulated.

Aging↗

PubMed1996

Ecdysteroid mediated muscle actin synthesis during the larval development of rice moth, Corcyra cephalonica.

Protein fractions from the whole body homogenates were separated on SDS-PAGE and the muscle actin band was identified by western blotting, using commercial antibody raised against chick back muscle actin (Sigma Chemical Co., USA). The antibody was found to be specific for muscle actin, as it did not cross react with cytoplasmic actin of the nervous system. The molecular weight of the muscle actin in Corcyra was found to be around 46 kDa. The concentration of actin was found to be more or less the same in penultimate and early-last instar larvae and it increased during mid and late-last instar development. Thereafter, it has dropped to its minimum during the pupal stage. But, once again it increased to its maximum in adults. Thorax-ligation in early and late-last instar larvae resulted in decreased synthesis of muscle actin and this was more pronounced after 48 h of ligation. Injection of 20-hydroxyecdysone to insects which were thorax-ligated for 24 and 48 h was found to significantly increase the concentration of actin, suggesting that the ecdysteroids mediate the muscle actin synthesis during the larval development of Corcyra.

Actins↗

PubMed1991

In vitro effect of nonsteroidal ecdysone agonist RH 5849 on fat body acid phosphatase activity in rice moth, Corcyra cephalonica (Insecta).

Nonsteroidal ecdysone agonist stimulates acid phosphatase activity in the fat body in vitro cultures obtained from ligated late-last instar larvae of Corcyra cephalonica. The agonist also stimulates general protein synthesis. This stimulation is both time as well as dose dependent (up to a dose of 1000 ng of the agonist). However, still higher concentrations (1500-4000 ng) tend to depress the degree of stimulation.

Acid Phosphatase↗

PubMed1991

Differential hormone regulation of acid DNase activity in the testes and fat body of Spodoptera litura (Lepidoptera-Insecta).

Acid DNase activity in the testes and fat body is high during the early larval instars which may be correlated with the extensive cell division seen in both the tissues during these stages. The increased enzyme activity, observed in the testes of the pupal stage, might be involved in the in vivo degradation of DNA in a large number of degenerating spermatocysts which occur during this stage. Total activity of acid DNase in the fat body is highest in pupal stage. Like acid phosphatase, this enzyme may also be involved in the process of remodelling of the fat body during metamorphosis. 20-Hydroxyecdysone (20-HE) does not have any effect on acid DNase activity in the testes but it alters the enzyme activity in the fat body. Juvenile hormone-I (JH-I) has no effect on the enzyme activity in the fat body.

Animals↗

PubMed1990

Juvenile hormone mediated DNA synthesis during larval development of Corcyra cephalonica (Insecta).

Large amount of DNA is synthesized during larval development of Corcyra and this is conspicuously seen in the early-last instar. Ligation in early-last instar causes a decline in both DNA content and DNA concentration. Radiolabelling studies show a low rate of DNA synthesis in isolated abdomens, suggesting that hormonal factors from the anterior half of the larvae play a regulatory role in the DNA metabolism. Juvenile hormone I (JH-I) treatment of ligated early-last instar stimulates DNA synthesis with consequent increase in DNA content and DNA concentration.

Abdomen↗

PubMed1989

Hormonal regulation of macromolecular synthesis in testes and accessory reproductive glands of Spodoptera litura during post-embryonic and adult development.

In S. litura testicular growth during the last larval instar and early pupal stage is associated with significant increase in DNA, RNA and protein contents. DNA synthesis is stimulated by 20-hydroxyecdysone (20-HE) in the penultimate instar testes. 20-HE injection in ligated late last instars increases the testicular weight and protein content. Accessory reproductive gland (ARG) development takes place during the mid and late pupal stages. Protein synthesis in the pharate adult ARG is stimulated by 20-HE. Juvenile hormone has no effect on ARG protein synthesis.

Animals↗

PubMed1989

Different pathways of DNA synthesis are operative in the fat body of Spodoptera litura (insecta) during larval and pupal development.

In Spodoptera litura, the DNA content of the fat body increases during the last larval instar. Radiolabelling studies reveal high degree of H3-thymidine incorporation in the fat cell DNA, during last larval stage of development. At prepupal stage the DNA synthesised during larval development is degraded, at least partially and the resultant nucleotides are most likely used as building blocks for the fat cell DNA synthesis during pupal development and pupal-adult metamorphosis, because very little H3 -thymidine injected into pupae is incorporated in DNA, though in fact, significant amount of DNA is synthesised during this period.

Animals↗

PubMed1988

Ecdysteroid mediated fat body acid phosphatase activity during larval development of rice moth, Corcyra cephalonica (Lepidoptera).

20-hydroxyecdysone (20-HE) stimulates acid phosphatase activity in the fat body of ligated late-last instar larvae. This effect is time dependent and the specific activity of enzyme increases significantly in hormone treated insects. 20-HE also stimulates general protein synthesis. Cycloheximide treatment either in conjunction with 20-HE or after hormone treatment blocks the increase in enzyme activity as well as increase in protein content. However, actinomycin D treatment does not alter the enzyme activity while it blocks the increase in total RNA as well as increase in protein content.

Acid Phosphatase↗

PubMed1988

Juvenile hormone inhibits the synthesis of major larval haemolymph proteins in rice moth, Corcyra cephalonica.

Larval haemolymph proteins (LHP), LHP49 and LHP46 are produced in the penultimate and last larval instars. Starvation during the early and mid stage of last instar development prevents the production of both LHPs. Decapitation in early and mid last instar stimulates LHP synthesis and their concentration in haemolymph increases, while ligation in last instar larvae blocks the production of LHPs. Application of exogenous JH lowers the synthesis of LHP49 and LHP46 in Corcyra. These observations suggests that LHP49 and LHP46 synthesis is activated during the periods when JH titres are either low or undetectable.

Animals↗