Browsing by Author "S.C. Lakhotia"

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1 (2)gl gene regulates late expression of segment polarity genes in Drosophila
(1995) Ashim Mukherjee; S.C. Lakhotia; J.K. Roy
To analyse the possible roles of Drosophila tumour suppressor genes, 1 (2)gl and 1 (2)gd, in differentiation programmes of imaginal cells, we investigated their interactions with two segment polarity genes, viz., cubitus interruptus Dominant (ci-D) and engrailed (en), by examining their patterns of expression in tumourous imaginal discs of 1 (2)gl4 or 1 (2)gd1 homozygous larvae. While the 1 (2)gd1 mutation did not have much effect, the areas of expression of ci-D and en in the tumourous discs of 1 (2)gl homozygous larvae were significantly increased and the anterior-posterior compartment boundary was no longer identifiable. To examine if the loss of en expression compartment boundary in 1 (2)gl tumourous discs was due to overproliferation of the posterior compartment cells or due to a deregulated expression of en in the anterior compartment cells, 1 (2)gl4 homozygous cell clones were generated in 1 (2)gl4 enlacZ/++ background. A distinct X-gal staining in 1 (2)gl homozygous clones in the anterior compartment in wing imaginal discs or in adult wings confirmed deregulated ectopic expression of en in 1 (2)gl mutant anterior compartment cells. We suggest that 1 (2)gl is involved in regulating post embryonic expression of segment polarity genes. © 1995.
3H-uridine incorporation in the puff 93D and in chromocentric heterochromatin of heat shocked salivary glands of Drosophila melanogaster
(Springer-Verlag, 1979) Tapas Mukherjee; S.C. Lakhotia
The autoradiographic patterns of 3H-uridine labelling of the major temperature shock puff sites and the chromocentric (β-)heterochromatin in heat shocked (37° C) salivary glands of Drosophila melanogaster have been studied. It is seen that in response to the heat shock treatment, four of the major temperature shock puffs (63BC, 87A, 87C and 95D) show a correlated level of 3H-uridine incorporation in a given nucleus. However, although the mean grain density on 93D puff is maximum in the heat shocked preparations, in individual nuclei this puff is labelled to a widely varying level and this variation in its labelling is statistically not correlated to the labelling of the other four temperature shock puffs in a nucleus. The chromocentric β-heterochromatin, which has been shown in several earlier studies to hybridize with temperature shock RNA fractions, is seen to be totally inactive in transcription after the heat shock. © 1979 Springer-Verlag.
A novel set of heat shock polypeptides in malpighian tubules of Drosophila melanogaster
(1989) S.C. Lakhotia; A.K. Singh
In contrast to the general notion of induction of a common set of heat shock polypeptides (HSP) in all cell types, heat shocked malpighian tubules (MT) of Drosophila melanogaster larvae did not synthesize the common set of HSP induced in salivary glands or brain ganglia of larvae and in gonads (testis or ovary) of adult flies. Instead, heat shocked MT of late 3rd instar larvae and freshly eclosed adults synthesized a novel set of polypeptides (MT-specific HSP) with a major induced band at 58 kd. Surprisingly, the MT of older flies synthesized both the MT-specific as well as the common set of HSP in response to heat shock. Fusion genes with hsp70 or hsp26 promoter linked to the lac-Z (beta galactosidase) or to ADH (alcohol dehydrogenase) reporter gene were also not induced in larval MT but showed good induction in the MT of older flies. This unexpected finding raises intriguing issues regarding the nature of MT-specific HSP, their genes and the cell type dependent induction of the two sets of HSP. © 1989, Indian Academy of Sciences. All rights reserved.
A simple and economical device to save water in water distillation systems in laboratories
(2008) Munnalal; Sitaram Tiwari; Rajesh; Amarnath Singh; Jagat Narayan Singh; Richa Arya; Akanksha; S.C. Lakhotia
[No abstract available]
A simple nail polish imprint technique for examination of external morphology of Drosophila eyes
(2006) Richa Arya; S.C. Lakhotia
[No abstract available]
A study of heterochromatin in Drosophila nasuta by the 5-bromodeoxyuridine-giemsa staining technique
(Springer-Verlag, 1979) S.C. Lakhotia; J.K. Roy; Mahesh Kumar
Larval brain ganglia of Drosophila nasuta were cultured in vitro in the presence of 5-bromodeoxyuridine for 1 or 5 h at 24° C and the air-dried chromosome preparations stained by the Hoechst 33258-Giemsa technique to reveal bromodeoxyuridine induced sister chromatid differentiation. In 1 h as well as 5 h preparations, 10-15% of well spread metaphase plates show a sister chromatid differentiation in only C-band heterochromatin regions of different chromosomes. We infer that this sister chromatid differentiation in all heterochromatic regions is seen after bromodeoxyuridine incorporation for only one replication cycle and is related to the presence of asymmetric A-T rich satellite sequences in all the C-band regions of D. nasuta karyotype. © 1979 Springer-Verlag.
A-T specific DNA ligands and hypotonic induced supercondensation of chromocentre in brain cells of Drosophila nasuta larvae in relation to their synthetic activities
(1984) J.K. Roy; S.C. Lakhotia
[No abstract available]
Absence of novel translation products in relation to induced activity of the 93D puff in Drosophila melanogaster
(Springer-Verlag, 1982) S.C. Lakhotia; T. Mukherjee
Salivary glands of Drosophila larvae were treated in vitro with benzamide or with a homogenate of heat shocked glands to specifically induce high transcriptional activity of the 93D puff. The newly synthesized 14C-amino acids labelled polypeptides in the treated and sister control glands were analysed by polyacrylamide gel electrophoresis, followed by gel autoradiography. The protein synthesis patterns in the treated glands in either case remain the same as in control glands. No novel polypeptide was seen which could be correlated with the high induced transcriptional activity of the 93D puff. This suggests that the 93D transcript/s is/are probably not translated. © 1982 Springer-Verlag.
Altered expression of the noncoding hsrω gene enhances poly-Q-induced neurotoxicity in Drosophila
(Taylor and Francis Inc., 2006) Sonali Sengupta; S.C. Lakhotia
In an earlier report two P-transposon insertion alleles of the noncoding hsrω gene, hsrω05241 and P292 were shown to enhance neurodegeneration caused by expression of ataxin-1 protein with expanded poly-Q in a Drosophila model. In present study, we examined the possible relation between hsrω gene expression and toxicity due to poly-Q pathogenesis. The Drosophila hsrω gene produces several noncoding transcripts in almost all cell types, of which the >10 kb long hsrω-n transcript organizes heterogeneous RNA binding (hnRNPs) and related proteins as nucleoplasmic omega speckles. We show that P insertion alleles of the hsrω gene, which cause its overexpression, dominantly enhance neurodegeneration in fly eyes expressing either expanded poly-Q (127Q) or mutant huntingtin protein. Null allele of Hrb87F gene, encoding hnRNPA1, and a novel gene's mutant allele (l(3)pl10 R), which affects the omega speckles, also dominantly enhance 127Q-induced neurodegeneration. The hsrω-n transcripts or the hnRNPs do not colocalize with the poly-Q nuclear inclusion bodies, neither in hsrω wild type, nor in hsrω mutant background. However, the levels of poly-Q and Hsp70 were significantly higher in hsrω mutant eye discs. Sequestration of hnRNPs and other related RNA-binding proteins by overexpression of hsrω transcripts in hsrω05241 or in l(3)pl10 R background or the reduced levels of Hrb87F protein seem to affect nuclear RNA metabolism, thus enhancing the toxicity due to poly-Q expansion. ©2006 Landes Bioscience.
Are biotechnology degree courses relevant?
(2008) S.C. Lakhotia
[No abstract available]
Ayurvedic biology-An unbiased approach to understand traditional health-care system
(Indian National Science Academy, 2016) S.C. Lakhotia
[No abstract available]
AYUSH advisory presents ominous outlook for research in traditional Indian healthcare systems
(Indian Academy of Sciences, 2019) S.C. Lakhotia; Kishor Patwardhan; Sanjeev Rastogi
[No abstract available]
Cell cycle and DNA content of mitotic cells in brain ganglia of drosophila larvae
(Springer India, 1995) S.C. Lakhotia; J.K. Roy; Sujata kar Chowdhuri
The programmes of replication of hetero- and euchromatin regions, mitotic cell cycle and the DNA content in metaphases in brain ganglia from late third instar larvae of Drosophila melanogaster (wild type and a tumour bearing mutant, 1(2)gl, strain) and of Drosophila nasuta were examined by autoradiography of [3H]thymidine labelled (continuous or pulse) cells and by cytophotometry, respectively. Brain ganglia labelled continuously with [3H]thymidine for 24 h in vitro showed a significantly high proportion of cells with incorporation of radioactivity restricted to heterochromatin only. Pulse labelling of brain ganglia from larvae of Drosophila melanogaster and Drosophila nasuta followed by chase for different time intervals showed that (i) the frequency of labelled metaphases was more than 50% within 15 to 30 min of chase and remained higher than 50% in nearly all the chase samples till 24 h, (ii) euchromatin labelled metaphases appeared with a low frequency within 1 to 4 h chase period but the heterochromatin labelled metaphases continued to be more common in the later chase samples also, (iii) single chromatid labelled second cycle metaphases were seen within 1 to 4 h after the pulse, but their frequency did not increase in the later samples. Cytophotometry of feulgen-DNA and Hoechst 33258 stained metaphases in late third instar larval brain ganglia revealed a greater variation in the DNA content of individual metaphases, although the means were close to the expected 4 C content. It appears that in relation to the known asymmetric cell divisions of neuroblast and other neural cells, the mitotically active cells in brain ganglia comprise a heterogenous population with widely varying lengths of the different phases of cell cycle; some of them may not cycle regularly and may possibly have a discontinuous S-phase. © 1995 Indian Academy of Sciences.
Cellular stress responses: Preface
(Indian Academy of Sciences, 1998) S.C. Lakhotia; A.K. Tripathi
[No abstract available]
Chromosomal organization of Drosophila tumours - I. Polytene chromosome organization and DNA synthesis in ovarian pseudonurse cells in otu mutants of D. melanogaster
(Springer-Verlag, 1987) P. Sinha; Arati Mishra; S.C. Lakhotia
In otu mutants of Drosophila melanogaster ovarian tumours develop because of the high mitotic activity of the mutant cystocytes; the latter are normally endopolyploid. In certain alleles of otu, however, a varying proportion of the mutant ovarian cystocytes undergo polyteny. Mutant cystocytes with polytene chromosomes are termed pseudonurse cells (PNC). Polytene chromosome morphology and banding patterns in PNC of otu1/otu3 flies were cytologically analysed. Extensive variability was noted in the quality of the banding pattern of the PNC chromosomes which ranged from highly condensed (condensed PNC chromosomes) to those with a banding pattern (banded PNC chromosomes) similar to that in larval salivary gland cells (SGC). Both the condensed and banded PNC chromosomes frequently enter into a diffuse state characterised by weakened synapsis of the polytene chromatids and alterations in their banding pattern (diffuse PNC chromosomes). Analysis of DNA synthesis patterns in the various morphological forms of PNC polytene chromosomes by 3H-thymidine autoradiography revealed a basic similarity to the pattern seen in polytene nuclei of larval SGC. Independently replicating sites, however, could be unambiguously identified only in banded PNC chromosomes. Comparison of late replicating sites in such PNC chromosomes with those of larval SGC showed a remarkable similarity in the two cell types. These results suggest a close correlation between the polytene chromosome banding pattern and its replicative organization. © 1987 Springer-Verlag.
Conservation of the 93D puff of Drosophila melanogaster in different species of Drosophila
(Springer-Verlag, 1982) S.C. Lakhotia; Ajit Kumar Singh
Temperature shock (TS) results in activation of a specific set of puffs in polytene nuclei of D. melanogaster. Earlier studies in this species from several laboratories revealed certain unique features of the major TS puff at 93D locus, which is also specifically induced by benzamide (BM) and by incubation of glands in heat shocked glands' homogenate (HSGH). We have now extended studies on TS response to several other species of Drosophila to ascertain whether loci homologous to 93D puff of D. melanogaster are present in other species. In polytene nuclei of two closely related (D. ananassae, D. kikkawai) and in two distantly related species (D. hydei, D. nasuta), six to nine puffs are induced by TS. Interestingly, in each species one of the major TS puffs, viz., 2L-2C in D. ananassae, E-11BC in D. kikkawai, 2R-48A in D. nasuta and 2-48C in D. hydei, is also specifically induced by BM, autologous species' HSGH and vitamine-B6 (vit-B6) treatment. HSGH of a different species fails to induce these puffs. These puffs thus resemble the 93D locus of D. melanogaster, although the 93D puff does not respond to vit-B6. These observations are discussed in relation to the conservation of 93D puff locus in different species of Drosophila. © 1982 Springer-Verlag.
Cytological identity of 93D-like and 87C-like heat shock loci in Drosophila pseudoobscura
(1984) P.K. Burma; S.C. Lakhotia
[No abstract available]
Developmental regulation and complex organization of the promoter of the non-coding hsrω gene of Drosophila melanogaster
(Indian Academy of Sciences, 2001) S.C. Lakhotia; T.K. Rajendra; K.V. Prasanth
The nucleus-limited large non-coding hsrω-n RNA product of the 93D or the hsrω gene of Drosophila melanogaster binds to a variety of RNA-binding proteins involved in nuclear RNA processing. We examined the developmental and heat shock induced expression of this gene by in situ hybridization of nonradioactively labelled riboprobe to cellular transcripts in intact embryos, larval and adult somatic tissues of wild type and an enhancer-trap line carrying the hsrω05241 allele due to insertion of a P-LacZ-rosy+ transposon at - 130 bp position of the hsrω promoter. We also examined LacZ expression in the enhancer-trap line and in two transgenic lines carrying different lengths of the hsrω promoter upstream of the LacZ reporter. The hsrω gene is expressed widely at all developmental stages; in later embryonic stages, its expression in the developing central nervous system was prominent. In spite of insertion of a big transposon in the promoter, expression of the hsrω05241 allele in the enhancer-trap line, as revealed by in situ hybridization to hsrω transcripts in cells, was similar to that of the wild type allele in all the embryonic, larval and adult somatic tissues examined. Expression of the LacZ gene in this enhancer-trap line was similar to that of the hsrω RNA in all diploid cell types in embryos and larvae but in the polytene cells, the LacZ gene did not express at all, neither during normal development nor after heat shock. Comparison of the expression patterns of hsrω gene and those of the LacZ reporter gene under its various promoter regions in the enhancer-trap and transgenic lines revealed a complex pattern of regulation, which seems to be essential for its dynamically varying expression in diverse cell types.
Different effects of 93D on 87C heat shock puff activity in Drosophila melanogaster and D. simulans
(Springer-Verlag, 1986) D. Kar Chowdhuri; S.C. Lakhotia
It is known that treatment of the 93D heat shock locus in Drosophila melanogaster with two inducers, eg. benzamide (BM) or colchicine plus heat shock, causes the 93D puff in polytene nuclei to regress and, at the same time, the 87A and 87C heat shock puffs to be expressed unequally. In view of the close phylogenetic relationship and similar banding pattern of polytene chromosomes of the sibling species D. melanogaster and D. simulans, we examined the expression of the 93D puff and its effects on the transcriptional activity of the 87A and 87C heat shock puffs in salivary glands of D. simulans and D. melanogaster x D. simulans hybrid larvae by autoradiography. As in D. melanogaster, the 93D puff was selectively induced by BM or colchicine and regressed when heat shock treatment was given in addition in D. simulans and in the interspecific hybrid. However, unlike in D. melanogaster, the relative activity of the 87A and 87C heat shock puffs on D. simulans chromosomes remained equal in glands exposed to heat shock in combination with BM or colchicine. In the nuclei of interspecific hybrids, the 87A and 87C loci on the two homologues responded in the same way as those of the respective parents. There was no evidence of a transvection effect. It is known that the 87C locus of D. simulans differs from that of D. melanogaster in not carrying the heat-inducible αβ sequences and therefore, it is proposed that the 93D effect on 87C puff activity in D. melanogaster is mediated via the αβ sequences. However, the role of possible structural differences in the 93D locus of the two species cannot be ruled out. © 1986 Springer-Verlag.
Dosage compensation of X-chromosome activity in interspecific hybrids of Drosophila melanogaster and D. simulans
(Springer-Verlag, 1981) S.C. Lakhotia; Arati Mishra; P. Sinha
We have used the unstable ring X-chromosome of D. melanogaster to generate XX/XO mosaics in the hybrid progeny from crosses between D. melanogaster females and D. simulans males. The functional properties of the polytene X-chromosome(s) in salivary glands of such XO/XX mosaic hybrid larvae have been analysed by autoradiography after 3H-uridine or 3H-thymidine labelling of the glands. The simulans X-chromosome in the hybrid XO nuclei displays typical pale staining, enlarged diameter, higher rate of transcription (nearly two times higher than each of the Xs in the XX nuclei in the same gland) and a faster completion of replication as would be the case in the original parental XO or XY nuclei. In the hybrid XX polytene nuclei, the melanogaster as well as the simulans X functions in the same manner as in female cells of the parents. The nucleolar transcription is also equal in the hybrid XX and XO nuclei. Thus it seems that despite the evolutionary diversification between these two species, the regulatory system which brings about the dosage compensation of X-chromosome activity has been conserved. © 1981 Springer-Verlag.