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Biomedical subjects

A Bharathi

Publications and source records attributed to A Bharathi.

At least 19 recordsLinked to original sources
PubMed1997

The human RAE1 gene is a functional homologue of Schizosaccharomyces pombe rae1 gene involved in nuclear export of Poly(A)+ RNA.

A Schizosaccharomyces pombe temperature-sensitive mutant, rae1-1, was previously identified by us as being defective in nuclear export of Poly(A)+ RNA when grown at restrictive temperature. Here, we report the isolation of the human homologue of the S. pombe rae1 gene. The RAE1 genes are highly conserved in evolution in both structure and function. The human RAE1 cDNA, when expressed from the CMV-promoter, can suppress partially the temperature sensitivity of the rae1-1 mutant. This is also reflected by increased Poly(A)+ RNA export at a restrictive temperature. An epitope tagged human Rae1p localizes to both the nucleus and the cytoplasm in transiently transfected HeLa cells. We discuss the potential role of Rae1p in nuclear cytoplasmic trafficking in yeast and higher eukaryotic cells.

Biological Transport↗
PubMed1997

Advancement through mitosis requires rae1 gene function in fission yeast.

Growth of the rae1-1 mutant of Schizosaccharomyces pombe at restrictive temperature results in accumulation of poly(A)+ RNA in the nucleus and a cell cycle arrest at the G2/M boundary. We demonstrate here that rae1 function is required for a process other than mRNA export which is essential for advancement through mitosis. Cells lacking rae1 function arrest with elevated Cdc2p kinase levels at a step before the formation of a mitotic spindle and without separation of the spindle pole bodies. Rae1p was localized to the nuclear periphery, consistent with a role in nucleocytoplasmic trafficking, which could include protein import. We propose a model where rae1 functions in cell cycle progression through trafficking of proteins required for mitosis.

CDC2 Protein Kinase↗
PubMed1997

Npp106p, a Schizosaccharomyces pombe nucleoporin similar to Saccharomyces cerevisiae Nic96p, functionally interacts with Rae1p in mRNA export.

To identify components of the mRNA export machinery in Schizosaccharomyces pombe, a screen was developed to identify mutations that were synthetically lethal with the conditional mRNA export allele rae1-167. Mutations defining three complementation groups were isolated, and here we report the characterization of npp106 (for nuclear pore protein of 106 kDa). This gene encodes a predicted protein that has significant similarity to the Nic96p nucleoporin of Saccharomyces cerevisiae. Consistent with Npp106p being a nucleoporin, a functional green fluorescent protein (GFP)-tagged Npp106p localized to the nuclear periphery. In contrast to NIC96, the npp106 gene is not essential. Moreover, a delta npp106 mutant did not show cytoplasmic mislocalization of a simian virus 40 nuclear localization signal-GFP-LacZ reporter protein, and a fraction of cells had accumulation of poly(A)+ RNA in the nucleus. A consequence of the synthetic lethality between rae1-167 and npp106-1 was the accumulation of poly(A)+ RNA in the nucleus when cells were grown under synthetic lethal conditions. In addition to npp106-1, which is a nonsense mutation that truncates the protein at amino acid 292, the delta npp106 mutation was synthetically lethal with rae1-167, suggesting that the synthetic lethality is a consequence of the loss of a function of npp106. We further demonstrate that a region between amino acids 74 and 348 of Npp106p is required for complementation of the synthetic lethality. These results uncover a potential direct or indirect involvement of Npp106p in mRNA export.

Amino Acid Sequence↗
PubMed1995

A mutation in the Schizosaccharomyces pombe rae1 gene causes defects in poly(A)+ RNA export and in the cytoskeleton.

A collection of fission yeast Schizosaccharomyces pombe conditional mutants was screened for defective nucleocytoplasmic transport of poly(A)+ RNA by fluorescence in situ hybridization. We identified a temperature-sensitive mutant that accumulated poly(A)+ RNA in the nucleus and have named it rae1-1, for ribonucleic acid export. All rae1-1 cells exhibit the defect in poly(A)+ RNA export within 30 min following a shift to the non-permissive temperature. In addition, in the rae1-1 mutant, actin and tubulin become disorganized, and cells undergo an irreversible cycle arrest. Results from experiments in which rae1-1 cells were arrested in various phases of the cell division cycle and then shifted to nonpermissive temperature suggest that cells are particularly vulnerable to loss of rae1 function during G2/M. However, the inability to export RNA from the nucleus to the cytoplasm was not limited to a particular phase of the cell division cycle. The rae1 gene was isolated by complementation and encodes a predicted protein of 352 amino acids with four beta-transducin/WD40 repeats.

Actins↗
PubMed1993

Effect of pesticides on growth of rhizobia and their host plants during symbiosis.

Effect of various pesticides (insecticides, fungicides and herbicides) has been studied on growth and efficiency of symbiotic properties of 3 fast growing Rhizobium sp. under green house conditions. The results revealed adverse effects on plant growth and nitrogen fixing capacity as measured by dry weight and total nitrogen content of plants infected with pesticide treated Rhizobium. Of the pesticides tested, herbicides were found to be more effective on the above parameters than the insecticides and fungicides.

Fabaceae↗
PubMed1991

Elimination of broad-host range plasmid vectors in Escherichia coli by curing agents.

A comparative study was made of the susceptibility of broad-host range vector plasmids belonging to Inc P1 and Q groups in Escherichia coli to various curing agents. Plumbagin and SDS eliminated RP4 (Inc P1 group) plasmid whereas pKT231 (Inc Q) and pRK2013 (having ColE1 replicon) were eliminated by hexamine ruthenium (III) chloride, alpha-santonin, coumermycin A1 and cis-dichloro diamine platinum (II). The curing activity of these agents was specific.

Aminocoumarins↗