Browsing by Author "Dhania, Narendra K."

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Fat body remodeling in Spodoptera litura F. (Lepidoptera: Noctuidae) during postembryonic development2017
(Association for Advancement of Entomology, 2017) Chauhan, Vinod K.; Dhania, Narendra K.; Ayinampudi, Pavani; Chaitanya, R. K.; Dutta-Gupta, Aparna
During insect metamorphosis, larval structures including fat body are replaced by the adult ones. This process involves lysosomal enzyme-mediated remodeling of fat body. The objective of this study is to characterize the events leading to fat body remodeling during postembryonic development in an important agricultural pest, Spodoptera litura. Present study showed that the fat body undergoes significant changes in its morphology as well as histology. During the larval stage the tissue is primarily synthetic and secretory in nature and releases large amount of macromolecules including hexamerins in the heamolyph. While at pre-pupal and pupal stages it acts as a storage tissue and accumulates number of protein granules. Radiolabelling and DNA analysis studies revealed higher content of DNA in the larval fat body. The decline seen in pre-pupae corroborated well with disintegration of nuclei which were remodeled during pupal and adult stages. Further, the role of an insect morphogenetic hormone, 20-hydroxyecdysone (20E) in fat body reorganization has also been elucidated. This study enables us to understand the basic mechanism and altered micro-environment of the dynamic fat body tissue during larval-pupal-adult transition and metamorphosis.
Larval mid-gut responses to sub-lethal dose of cry toxin in lepidopteran pest Achaea janata
(Frontiers Media S.A., 2017) Chauhan, Vinod K.; Dhania, Narendra K.; Chaitanya, R. K.; Senthilkumaran, Balasubramanian; Dutta-Gupta, Aparna; Chauhan, V.K.; Dhania, N.K.; Chaitanya, R.K.; Senthilkumaran, B.; Dutta-Gupta, A.
The lack of homogeneity in field application of Bacillus thuringiensis formulation often results in ingestion of sub-lethal doses of the biopesticide by a fraction of pest population and there by promotes the toxin tolerance and resistance in long term. Gut regeneration seems to be one of the possible mechanism by which this is accomplished. However, the existing information is primarily derived from in vitro studies using mid-gut cell cultures. Present study illustrates cellular and molecular changes in mid-gut epithelium of a Bt-susceptible polyphagous insect pest castor semilooper, Achaea janata in response to a Cry toxin formulation. The present report showed that prolonged exposure to sub-lethal doses of Cry toxin formulation has deleterious effect on larval growth and development. Histological analysis of mid-gut tissue exhibits epithelial cell degeneration, which is due to necrotic form of cell death followed by regeneration through enhanced proliferation of mid-gut stem cells. Cell death is demonstrated by confocal microscopy, flow-cytometry, and DNA fragmentation analysis. Cell proliferation in control vs. toxin-exposed larvae is evaluated by bromodeoxyuridine (BrdU) labeling and toluidine blue staining. Intriguingly, in situ mRNA analysis detected the presence of arylphorin transcripts in larval mid-gut epithelial cells. Quantitative PCR analysis further demonstrates altered expression of arylphorin gene in toxin-exposed larvae when compared with the control. The coincidence of enhanced mid-gut cell proliferation coincides with the elevated arylphorin expression upon Cry intoxication suggests that it might play a role in the regeneration of mid-gut epithelial cells. ? 2017 Chauhan, Dhania, Chaitanya, Senthilkumaran and Dutta-Gupta. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY).