Browsing by Author "Singh, B N"
Now showing 1 - 20 of 40
Results Per Page
Sort Options
Item Alkaptonuria.(1989-11-01) Singh, B N; Mehrotra, S; Bhargava, B; Agarwal, SA case of alkaptonuria with its various sequelae in the form of ochronosis, ochronotic arthropathy, spondylitis and prostatic calculi is reported. The case is of interest as it presented with hepatocellular failure and hepatitis B surface antigenaemia.Item Antigenic difference in free-living & parasitic amoebae as revealed by immobilization reaction.(1966-01-01) Singh, L M; Singh, B NItem Balanced chromosomal polymorphism in experimental populations of Drosophila ananassae Doleschall.(1972-07-01) Singh, B N; Ray-Chaudhuri, S PItem Behaviour genetics of Drosophila: non-sexual behaviour.(2005-08-01) Sisodia, Seema; Singh, B NItem Characterization of glycosyl phosphatidylinositol lipids of parasitic protozoans: Leishmania mexicana mexicana promastigotes, Trypanosoma cruzi Peru epimastigotes and Tritrichomonas foetus.(1990-12-01) Singh, B N; Costello, C E; Beach, D H; Holz, G GGlycosyl phosphatidylinositol lipids of cultured L.mex, mexicana LV732 promastigotes, T. cruzi Peru epimastigotes and Tritrichomonas foetus have been isolated and characterized using metabolic labelling and chromatographic and mass spectrometric (MS) techniques. TLC of the unsaponifiable lipid fractions of L. mex. mexicana and T. cruzi obtained from DEAE Sephadex A-25 followed by Iatrobead column chromatography showed three inositol phosphate-containing lipid components. [3H]myo-inositol, [3H]palmitic acid or H3 32PO4 lipid precursors were incorporated into these three lipid components. Fraction 2 (LM2 and TCP-2) comprises inositol phosphate ceramides. The other two fractions appear to contain mono-O-alkyl and di-O-alkyl glycerol inositol phosphates. Lyso-1-O-alkyl phosphatidylinositols could be cleaved by treatment of PI-specific phosphalipase C. The di-O-alkyl-phospho inositols of these parasites being the first dialkylglycerol lipids reported from eukaryotic membranes raises the possibility of chemotherapy for leishmaniasis and trypanosomiasis based upon functional impairment of alkyl ether lipids. Tritrichomonas foetus contains two major glycophosphosphingolipids, designated TF1 and TF2, which are metabolically labelled with [3H]myo-inositol and H3 32PO4. Both lipids contained ceramides. The major ceramide contains the 18:0 and 18:1 bases and 16:0 N-acyl group. The major glycolipid fraction (TF1) contains fucose linked to inositol diphosphate; one of the phosphates being linked to the ceramide moiety, and the other to ethanolamine. TF1 appears to be a novel class of glycophosphosphingolipid, which may be a part of a membrane anchor.Item Choice of oviposition site between surface of the medium and paper in four Indian species of Drosophila.(2001-04-09) Srivastava, T; Singh, B NChoice of oviposition site between surface of the medium and paper positioned vertically on the medium by females was studied in four species of Drosophila: D. ananassae, D. bipectinata, D. malerkotliana, and D. biarmipes. Several geographic strains of these species were used. Females of all the four species laid greater proportions of eggs on the surface of medium as compared to surface of the paper. Thus all the four species tested show preference for oviposition on surface of medium. When the comparison is made for oviposition on paper among the four species, D. ananassae lays more eggs on the surface of paper as compared to other three species.Item Drosophila bipectinata species complex.(2001-09-08) Singh, S; Singh, B NThe Drosophila bipectinata species complex belongs to the ananassae subgroup of the melanogaster species group (Genus Drosophila, Subgenus Sophophora). The members of the complex are: D. bipectinata, D. parabipectinata, D. malerkotliana, and D. pseudoananassae. Of the four species, D. bipectinata is most widely distributed. Females are indistinguishable, but males are distinguishable by their sex-comb teeth number and pattern and by abdominal colouration. Chromosomal inversions have been detected in these species. In natural populations of D. bipectinata the frequency of inversions and the level of inversion heterozygosity were found to be very low but in laboratory stocks inversions persisted for more than 20 generations due to heterotic buffering. On an average 9.3 fixed interspecific inversions separate each species pair. Non-random association between linked inversions indicated epistatic interaction in natural populations of D. bipectinata. Certain spontaneous mutations were detected and mapped for the first time in D. bipectinata. Low frequency of spontaneous male recombination has also been reported in D. bipectinata. Sexual isolation study in the complex indicated strong preference for homogamic mating. The results also indicated incomplete sexual isolation among different members of this complex. The isolation estimate among six different geographic populations of D. bipectinata ranged from 0.54 - 0.92 representing positive assortative mating which is an evidence for incipient sexual isolation. Incipient sexual isolation was also found within D. malerkotliana and D. parabipectinata . Chromosomal, hybridization and allozyme studies revealed close phylogenetic relationship among the four species of the bipectinata complex. Mitochondrial DNA study revealed net nucleotide difference (delta) between these species to be very small (0.0002 +/- 0.0008) reflecting closeness. Evidence for genetic control of sexual activity and existence of sexual selection in D. bipectinata has been shown on the basis of mating propensity tests carried out on geographic strains, their hybrids and diallel crosses. Significant variation was found among the strains tested with respect to courtship time, duration of copulation and fertility. A positive correlation between duration of copulation and fertility in D. bipectinata was found. Evidence for rare-male mating advantage was also found in D. bipectinata. A positive response to selection for high and low mating activity provided evidence for polygenic control of this phenomenon in D. bipectinata. Bilateral outgrowths on thorax, a unique phenotype, reported for the first time in D. bipectinata has been shown to affect mate recognition ability. Results of the study on pupation site preference (larval behaviour) and oviposition site preference (non-sexual behaviour) have also been included.Item Effect of biotic and abiotic factors on pupation height in four species of Drosophila.(1993-11-01) Pandey, M B; Singh, B NEffect of different biotic and abiotic factors such as sex, density, larval development time, moisture, temperature and light on pupation height were tested in Drosophila ananassae, D. bipectinata, D. malerkotliana and D. biarmipes which are commonly distributed in India. In the four species there are no sex differences in pupation height. Density of larvae and moisture content of food medium strongly influence pupation height. Larval development time, light and temperature also affect pupation height but there are intra- and interspecific variations in response to these factors for pupation site preference. Thus pupation site preference in these Indian species of Drosophila is influenced by various biotic and abiotic factors. The comparison of the present results with those found in other species clearly indicates that different species may vary in their response to different factors.Item Effect of directional selection for body size on fl uctuating asymmetry in certain morphological traits in Drosophila ananassae.(2009-06) Vishalakshi, C; Singh, B NVariation in the subtle differences between the right and left sides of bilateral characters or fl uctuating asymmetry (FA) has been considered as an indicator of an organism’s ability to cope with genetic and environmental stresses during development. However, due to inconsistency in the results of empirical studies, the relationship between FA and stress has been the subject of intense debate. In this study, we investigated whether stress caused by artifi cial bidirectional selection for body size has any effect on the levels of FA of different morphological traits in Drosophila ananassae. The realised heritability (h2) was higher in low-line females and high-line males, which suggests an asymmetrical response to selection for body size. Further, the levels of FA were compared across 10 generations of selection in different selection lines in both sexes for sternopleural bristle number, wing length, wing-to-thorax ratio, sex combtooth number and ovariole number. The levels of FA differed signifi cantly among generations and selection lines but did not change markedly with directional selection. However, the levels of FA were higher in the G10 generation (at the end of selection) than G0 (at the start of selection) but lower than the G5 generation in different selection lines, suggesting that the levels of FA are not affected by the inbreeding generated during the course of selection. Also, the levels of FA in the hybrids of high and low lines were signifi cantly lower than the parental selection lines, suggesting that FA is infl uenced by hybridisation. These results are discussed in the framework of the literature available on FA and its relationship with stress.Item Effect of directional selection on spontaneous male recombination in Drosophila ananassae.(1992-01-01) Mohanty, S; Singh, B NArtificial selection was carried out for high and low spontaneous male recombination values in D. ananassae for nine generations by using cu b se marker (second chromosome) and wild stocks which were free from heterozygous chromosome inversions. The mean crossing-over frequency of nine generations was 2.22, 0.70 and 1.20% in high, low and control lines respectively. The values of regression coefficient and realized heritability also indicated that male recombination was affected by selection. However, response to selection was more pronounced in high line as compared to low line. This provides evidence that spontaneous male crossing-over in D. ananassae is under polygenic control.Item Effect of mutation on mating propensity in Drosophila biarmipes.(1993-11-01) Singh, B N; Pandey, M BBy using multiple-choice technique, mating success between purple eye colour mutant and wild type D. biarmipes was studied in an Elens-Wattiaux mating chamber. Red eyed (wild type) males were more successful in mating than mutant males. However, mutant females were more receptive than wild females. The results suggest that purple eye colour mutation affects mating propensity in D. biarmipes.Item Evidence for random genetic drift in laboratory populations of Drosophila ananassae.(1988-02-01) Singh, B NItem Factors inducing excystation in free-living amoebae.(1971-07-01) Singh, B N; Datta, T; Dutta, G PItem Genetic basis of hybrid male sterility among three closely related species of Drosophila.(2005-05-20) Mishra, Paras Kumar; Singh, B NThe genetic basis of hybrid male sterility among three closely related species, Drosophila bipectinata, D. parabipectinata and D. malerkotliana has been investigated by using backcross analysis methods. The role of Y chromosome, major hybrid sterility (MHS) genes (genetic factors) and cytoplasm (non-genetic factor) have been studied in the hybrids of these three species. In the species pair, bipectinata--parabipectinata, Y chromosome introgression of parabipectinata in the genomic background of bipectinata and the reciprocal Y chromosome introgression were unsuccessful as all males in second backcross generation were sterile. Neither MHS genes nor cytoplasm was found important for sterility. This suggests the involvement of X-Y, X-autosomes or polygenic interactions in hybrid male sterility. In bipectinata--malerkotliana and parabipectinata--malerkotliana species pairs, Y chromosome substitution in reciprocal crosses did not affect male fertility. Backcross analyses also show no involvement of MHS genes or cytoplasm in hybrid male sterility in these two species pairs. Therefore, X- autosome interaction or polygenic interaction is supposed to be involved in hybrid male sterility in these two species pairs. These findings also provide evidence that even in closely related species, genetic interactions underlying hybrid male sterility may vary.Item Genetics of sexual behaviour in Drosophila.(2005-07-02) Sisodia, Seema; Singh, B NThe analysis of genetics of behaviour within and between species provides important clues about the forces shaping the evolution of behavioural genes. In Drosophila, a number of key processes such as emergence from the pupal case, locomotor activity, feeding, olfaction and aspects of mating behaviour are under circadian regulation. Genes controlling sexual behaviour are likely to control species specific differences in courtship that are involved in reproductive isolation of closely related species. Courtship in Drosophila is characterized by a series of stereotyped behaviours that lead to copulation and more than 30 genes have been identified through mutations that affect one or more of these elements. Although curiosity about behavioural differences between the sexes undoubtedly predates recorded history, little efforts have been made to uncover the molecular basis of male and female courtship. The brain and nervous system functions that underlie sex-specific behaviour are of obvious importance to all animals including humans. To understand behaviour related to sex it is important to distinguish those aspects that are controlled genetically. The isolation and analysis of Drosophila mutants with altered sexual orientation lead to the identification of novel branches in the sex-determination cascade, which govern the sexually dimorphic development of the nervous system.Item Geographic distribution of I-R and P-M systems of hybrid dysgenesis in Indian populations of Drosophila melanogaster.(1993-05-01) Singh, B N; Pandey, M BItem Interaction between selection and genetic drift in laboratory populations of Drosophila bipectinata.(1997-02-01) Banerjee, R; Singh, B NTo study the effect of selection and random genetic drift in laboratory populations of D. bipectinata, cut wing mutant and wild type stocks were crossed in several bottles. All the lines were maintained for several generations and in each generation the number of wild type and mutant flies was scored. Based on the number of two types of males, the frequency of cut gene and its normal allele was calculated for different bottles since ct is a sex-linked mutation and males are hemizygous. Interestingly, the cut gene was quickly eliminated in all the populations which is due to selection affecting fitness of two types of flies. However, there was considerable fluctuation in gene frequency among different populations and also there was increase in the cut gene frequency in certain generations as compared to previous generation which is caused due to effect of genetic drift which operates in small populations.Item Intra- and interspecies variations in pupation height in Drosophila.(1991-10-01) Singh, B N; Pandey, MIn order to study the pupation site preference which is an important component of larval behaviour, pupation height was scored in Drosophila ananassae, D. bipectinata and D. malerkotliana by using a large number of strains of these species. The mean pupation height of different strains ranged from 1.1 to 8.7 mm in D. ananassae, from 0.41 to 0.75 mm in D. bipectinata and from 1.0 to 1.3 mm in D. malerkotliana. The analysis of variance and t-test were performed to test intre- and interspecies variations in pupation height. These tests revealed significant variation among three species. Significant variations among different strains of the same species were also found in D. ananassae and D. bipectinata. These observations provide evidence for intra- and interspecies variations in pupation height in Drosophila. Variations among different strains of the same species in pupation height are attributable to genetic heterogeneity among the strains.Item Intra-and interchromosomal effects of heterozygous inversions on recombination in the third chromosome of Drosophila ananassae.(1991-01-01) Singh, B N; Mohanty, SIn order to study intra-and interchromosomal effects of heterozygous inversions on recombination in the third chromosome of D.ananassae, experiments were conducted using Stw-pr marker stock and five wild stocks with known karyotypes. The stocks used were homozygous for standard or inverted gene sequence in 2L, 3L, and 3R. Recombination was investigated in both sexes. There was complete absence of crossing-over in males in all the experiments which appeared to be the characteristic of marker stock as spontaneous male crossing-over was reported earlier with the same wild stocks when the second chromosome markers were used. Based on the data of karyotypically homozygous F1 females, the map distance between stw-pr was 36.55 map units. The heterozygosity due to a lengthy inversion in 2L increased the level of crossing-over between stw-pr genes of the third chromosome indicating interchromosomal effect. There was a considerable reduction in the rate of recombination between the same markers due to inversion heterozygosity in 3R indicating intrachromosomal effect. However, 3L inversion heterozygosity had no effect on crossover rate. These results provide evidence for intra-and interchromosomal effects of inversions on crossing-over in the third chromosome of D. ananassae.Item Intraspecific sexual isolation in Drosophila.(1992-04-01) Singh, B N; Chatterjee, SIntraspecific sexual isolation was examined among wild strains of Drosophila malerkotliana, D. parabipectinata and D. pseudoananassae by multiple-choice method in Elens-Wattiaux mating chamber. In D. pseudoananassae, mating between two strains tested was random and isolation estimate was close to one. In one out of 6 crosses, involving geographic strains of D. malerkotliana, there was significant deviation from randomness and isolation estimate remained low which shows non-random (preferential or positive assortative) mating. In D. parabipectinata, the deviation from randomness was statistically significant due to higher number of homogamic matings in three crosses involving wild strains derived from geographically distant places and isolation estimate remained low in these crosses. The results provide evidence for incipient sexual isolation within D. malerkotliana and D. parabipectinata as a result of genetic divergence.