• Volume 26, Issue 1

      March 2001,   pages  1-120

    • Triclosan and fatty acid synthesis inPlasmodium falciparum: New weapon for an old enemy

      Gurpur Praveen Bhat Namita Surolia

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    • Retinitis pigmentosa: mutations in a receptor tyrosine kinase gene,MERTK

      Arun Kumar

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    • Getting the beat

      Mohinish Shukla

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    • Non-redundant tumour suppressor functions of transforming growth factor beta in breast cancer

      Mohamad Azhar

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    • Glutamate synthase: An archaeal horizontal gene transfer?

      H Benan Dincturk

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    • Information theory: A guide in the investigation of disease

      J A Morris

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      The development of disease and the preservation of health can be analysed in terms of both software and hardware. The software approach, based on information theory, allows biologists to narrow down the range of possibilities and frame hypotheses to direct epidemiological and laboratory based research. These ideas follow from the basic principles which apply to all systems that process information: (i) finite capacity, (ii) finite probability of error, (iii) the error rate rises with age and (iv) complex systems need a high level of redundancy.

    • Developmental regulation and complex organization of the promoter of the non-codinghsrω gene ofDrosophila melanogaster

      S C Lakhotia T K Rajendra K V Prasanth

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      The nucleus-limited large non-coding hsrω-n RNA product of the93D or thehsrω gene ofDrosophila 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 byin 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 thehsrω05241 allele due to insertion of aP-LacZ-rosy+ transposon at — 130 bp position of thehsrω promoter. We also examinedLacZ expression in the enhancer-trap line and in two transgenic lines carrying different lengths of thehsrω promoter upstream of theLacZ reporter. ThehsrΩ 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 thehsrω05241 allele in the enhancer-trap line, as revealed byin 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 theLacZ gene in this enhancer-trap line was similar to that of thehsrω RNA in all diploid cell types in embryos and larvae but in the polytene cells, theLacZ gene did not express at all, neither during normal development nor after heat shock. Comparison of the expression patterns ofhsrω gene and those of theLacZ 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.

    • Characterization of chicken riboflavin carrier protein gene structure and promoter regulation by estrogen

      Nandini Vasudevan Urvashi Bahadur Paturu Kondaiah

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      The chicken riboflavin carrier protein (RCP) is an estrogen induced egg yolk and white protein. Eggs from hens which have a splice mutation in RCP gene fail to hatch, indicating an absolute requirement of RCP for the transport of riboflavin to the oocyte. In order to understand the mechanism of regulation of this gene by estrogen, the chicken RCP gene including 1 kb of the 5′ flanking region has been isolated. Characterization of the gene structure shows that it contains six exons and five introns, including an intron in the 5′ untranslated region. Sequence analysis of the 5′ flanking region does not show the presence of any classical, palindromic estrogen response element (ERE). However, there are six half site ERE consensus elements. Four deletion constructs of the 5′ flanking region with varying number of ERE half sites were made in pGL3 basic vector upstream of the luciferase-coding region. Transient transfection of these RCP promoter deletion constructs into a chicken hepatoma cell line (LMH2A) showed 6–12-fold transcriptional induction by a stable estrogen analogue, moxesterol. This suggests that the RCP gene is induced by estrogen even in the absence of a classical ERE and the half sites of ERE in this promoter may be important for estrogen induction.

    • Early localization of NPA58, a rat nuclear pore-associated protein, to the reforming nuclear envelope during mitosis

      Radhika Ganeshan Nandini Rangaraj Veena K Parnaik

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      We have studied the mitotic reassembly of the nuclear envelope, using antibodies to nuclear marker proteins and NPA58 in F-111 rat fibroblast cells. In earlier studies we have proposed that NPA58, a 58 kDa rat nuclear protein, is involved in nuclear protein import. In this report, NPA58 is shown to be localized on the cytoplasmic face of the envelope in interphase cells, in close association with nuclear pores. In mitotic cells NPA58 is dispersed in the cytoplasm till anaphase. The targeting of NPA58 to the reforming nuclear envelope in early telophase coincides with the recruitment of a well-characterized class of nuclear pore proteins recognized by the antibody mAb 414, and occurs prior to the incorporation of lamin B1 into the envelope. Significant protein import activity is detectable only after localization of NPA58 in the newly-formed envelope. The early targeting of NPA58 is consistent with its proposed role in nuclear transport.

    • Pleiotropic morphological and abiotic stress resistance phenotypes of the hyper-abscisic acid producing Abo mutant in the periwinkleCatharanthus roseus

      Shashi Pandey Rai Rajesh Luthra Madan Mohan Gupta Sushil Kumar

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      The pleiotropic properties of aabo abo (Abo) γ-ray induced mutant ofCatharanthus roseuscv. Nirmal, selected among the M2 generation seeds for ability to germinate at 45°C, are described. The mutant produced seeds possessing tricotyledonous embryos, unlike the typically dicotyledonous embryos present in the wild type Abo+ seeds. In comparison to Abo+ adults, the mutant plants had short stature and lanceolate leaves. The vascular bundles in the leaves and stem were poorly developed. Leaf surfaces were highly trichomatous, epidermal, cortex and mesophyll cells were small sized and a large majority of stomata were closed. Besides high temperature, the mutant was salinity and water-stress tolerant. The abscisic acid (ABA) content in the leaves was about 500-fold higher. The genetic lesionabo responsible for the above pleiotropy was recessive and inherited in Mendelian fashion. The seedlings and adult plants of the mutant accumulated higher proline than Abo+ plants. The phenotypes ofabo abo mutants permitted the conclusions that (i) the mutant synthesizes ABA constitutively, (ii) both ABA-dependent and ABA independent pathways for proline and betaine accumulation are functional in the mutant, and (iii) cell division, elongation and differentiation processes in embryo and adult plant stages are affected in the mutant.

    • Incipient sexual isolation in thenasuta-albomicans complex ofDrosophila: No-choice experiments

      M T Tanuja N B Ramachandra H A Ranganath

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      Drosophila nasuta nasuta andDrosophila nasuta albomicans are cross-fertile races ofDrosophila. Hybridization between these races in the laboratory has given rise to new races (Cytoraces), among which karyotypic composition differs from one another and also from those of the parental races. In this study, we search for the evidence of incipient reproductive isolation among the parental races and four Cytoraces by assessing the fraction of no-matings, mating latency and copulation duration in all possible types of homo- and heterogamic crosses (N = 4184). In no-choice conditions, the latency time (time to initiation of copulation) is lower in homogamic crosses than in heterogamic crosses for both parental races and Cytoraces. Latency time and copulation duration are negatively correlated, whereas fraction of no matings is positively correlated with latency time. Thus these six closely related races of thenasuta-albomicans complex show the initiation of the earliest stages of pre-zygotic isolation, manifested as a tendency for matings to be initiated earlier and more often, and for a longer duration, among homogamic rather than heterogamic individuals.

    • Biological factors underlying regularity and chaos in aquatic ecosystems: Simple models of complex dynamics

      A B Medvinsky S V Petrovskii D A Tikhonov I A Tikhonova G R Ivanitsky E Venturino H Malchow

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      This work is focused on the processes underlying the dynamics of spatially inhomogeneous plankton communities. We demonstrate that reaction-diffusion mathematical models are an appropriate tool for searching and understanding basic mechanisms of complex spatio-temporal plankton dynamics and fractal properties of planktivorous fish school walks.

    • Chaos and regular dynamics in model multi-habitat plankton-fish communities

      A B Medvinsky S V Petrovsk I A Tikhonova E Venturino H Malchow

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      This is work is focused on the role of diffusive interaction between separate habitats in a patchy environment in plankton pattern formation. We demonstrate that conceptual reaction-diffusion mathematical models constitute an appropriate tool for searching and understanding basic mechanisms of plankton pattern formation and complex spatio-temporal plankton dynamics.

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