• Pritha Ray

      Articles written in Journal of Biosciences

    • hsp 83 mutation is a dominant enhancer of lethality associated with absence of the non-protein codinghsrω locus inDrosophila melanogaster

      S C Lakhotia Pritha Ray

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      Thehrsω or the 93D heat shock locus ofDrosophila melanogaster, which does not code for any protein, has an important role in development since nullosomy of this locus in transheterozygotes for two overlapping deficiencies, viz.,Df(3R)eGp4 (eGp4) andDf(3R)GC14 (GC14), is known to cause a high (∼ 80%) mortality with the small number of escapee nullosomic flies being sterile, weak and surviving for only a few days. We now show that a majority of thehsrω-nulosomics die as embryo and that the 20% escapee embryos develop slower compared to their sibs carrying either one or two copies of thehsrω locus but after hatching survive to pupal/imago stage. Most interestingly, we further show that when onehsp83 mutant allele (hsp83e4A) is introduced ineGp4/GC14 trans-heterozygotes, practically none of thehsrω-nullosomic embryos develop beyond the 1st instar larval stage. The specificity of this interaction betweenhsp83 andhsrω genes was further confirmed by examining the effect of thehsp83 mutant allele on other mutations in the 93D cytogenetic region. Therefore, we conclude that thehsp83 mutation acts as a dominant enhancer of the lethality associated with nullosomy for thehsrω gene. The observed genetic interaction between these two members of the heat shock gene family during normal embryonic development ofDrosophila reveals novel aspects of their biological functions.

    • Interaction of the non-protein-coding developmental and stress-induciblehsrω gene withRas genes ofDrosophila melanogaster

      Pritha Ray S C Lakhotia

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      The93D orhsrω (hsr-omega) is an unusual non-protein-coding gene which shows a dynamic developmental expression in most cell types ofDrosophila melanogaster and which, besides being a member of the heat shock gene family, is uniquely induced in polytene cells by a variety of amides. We briefly review the various aspects of this gene's organization, regulation and inducible properties and present our recent data to show that, similar to our earlier report of interaction between thehsrω andhsp83 genes, mutations at theRas1 or theRas3 gene ofD. melanogaster also dominatly enhance the pre-pupal and pupal lethality of embryos that are nullosomic for this gene. In the absence of any protein product, thehsrw transcripts are suggested to interact with the Ras 1 signaling cascade. The interaction of a non-translatable, developmentally produced as well as heat and other stress inducible RNA with the Ras signaling proteins and with the Hsp83 chaperone protein opens new possibilities for understanding of functions of this intriguing gene.

    • A bubaline-derived satellite DNA probe uncovers generic affinities of gaur with other bovids

      Pritha Ray Supriya Gangadharan Munmun Chattopadhyay Anu Bashamboo Sunita Bhatnagar Pradeep Kumar Malik Sher Ali

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      DNA typing using genome derived cloned probes may be conducted for ascertaining genetic affinities of closely related species. We analysed gaurBos gaurus, cattleBos indicus, buffaloBubalus bubalis, sheepOvis aries and goatCapra hircus DNA using buffalo derived cloned probe pDS5 carrying an array ofBamHI satellite fraction of 1378 base residues to uncover its genomic organization. Zoo-blot analysis showed that pDS5 does not cross hybridize with non-bovid animals and surprisingly with female gaur genomic DNA. The presence of pDS5 sequences in the gaur males suggests their possible location on the Y chromosome. Genotyping of pDS5 withBamHI enzyme detected mostly monomorphic bands in the bubaline samples and polymorphic ones in cattle and gaur giving rise to clad specific pattern. Similar typing withRsaI enzyme also revealed clad specific band pattern detecting more number of bands in buffalo and fewer in sheep, goat and gaur samples. Copy number variation was found to be prominent in cattle and gaur withRsaI typing. Our data based on matched band profiles (MBP) suggest that gaur is genetically closer to cattle than buffalo contradicting the age-old notion held by some that gaur is a wild buffalo. The pDS5 clone has a potential for estimating the generic and genetic relationship amongst closely related bovid species.

    • Multimodality molecular imaging of disease progression in living subjects

      Pritha Ray

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      The enormous advances in our understanding of the progression of diseases at the molecular level have been supplemented by the new field of ‘molecular imaging’, which provides for in vivo visualization of molecular events at the cellular level in living organisms. Molecular imaging is a noninvasive assessment of gene and protein function, protein–protein interaction and/or signal transduction pathways in animal models of human disease and in patients to provide insights into molecular pathogenesis. Five major imaging techniques are currently available to assess the structural and functional alterations in vivo in small animals. These are

      optical bioluminescence and fluorescence imaging techniques,

      radionuclide-based positron emission tomography (PET) and single photon emitted computed tomography (SPECT),

      X-ray-based computed tomography (CT),

      magnetic resonance imaging (MRI) and

      ultrasound imaging (US).

      Functional molecular imaging requires an imaging probe that is specific for a given molecular event. In preclinical imaging, involving small animal models, the imaging probe could be an element of a direct (`direct imaging’) or an indirect (`indirect imaging’) event. Reporter genes are essential for indirect imaging and provide a general integrated platform for many different applications. Applications of multimodality imaging using combinations of bioluminescent, fluorescent and PET reporter genes in unified fusion vectors developed by us for recording events from single live cells to whole animals with high sensitivity and accurate quantification are discussed. Such approaches have immense potential to track progression of metastasis, immune cell trafficking, stem cell therapy, transgenic animals and even molecular interactions in living subjects.

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