Biomedical subjects

R Kothary

Publications and source records attributed to R Kothary.

41 records · Page 3Linked to original sources

PubMed1988

A transgene containing lacZ inserted into the dystonia locus is expressed in neural tube.

The site of integration of transgenes in the host genome can affect levels of expression and occasionally confer ectopic patterns of expression on otherwise tissue-specific genes. We describe here a line of mice in which an hsp68-lacZ transgene is expressed in unstressed developing neural tissue and where the transgene insertion has caused a mutation of a neural tissue-specific gene, dystonia musculorum (dt). This coincidence suggests that expression of the hsp68-lacZ construct may be controlled directly by cis-acting regulatory sequences that normally control the developmental expression of the dt gene. Such constructs may serve as useful tools for identifying new tissue-specific enhancers and their associated genes.

Animals↗

PubMed1988

Polytene chromosomes in mouse trophoblast giant cells.

Mouse trophoblast giant cells undergo successive rounds of DNA replication resulting in amplification of the genome. It has been difficult to determine whether giant cell chromosomes are polyploid as in liver cells or polytene as in Dipteran salivary glands because the chromosomes do not condense. We have examined the pattern of hybridization of mouse giant cells with a variety of in situ chromosome markers to address this question. Hemizygous markers displayed one hybridization signal per nucleus in both diploid and giant cells, while homozygous markers displayed two signals per nucleus in both cell types. These patterns are consistent with cytological evidence indicating that giant cell chromosomes are polytene rather than polyploid. However, in contrast to the situation in Dipteran salivary glands, the two homologues do not appear to be closely associated. We conclude that the mechanism of giant cell DNA amplification involves multiple rounds of DNA replication in the absence of both karyokinesis and cytokinesis, and that sister chromatids, but not homologous chromosomes, remain closely associated during this process.

Animals↗

PubMed1987

Cell-lineage-specific expression of the mouse hsp68 gene during embryogenesis.

Transcription of the mouse hsp68 and hsc70 genes in embryonal carcinoma cells, various embryonic and extraembryonic tissues, and some adult tissues has been assessed using cloned probes to the mouse hsp68 gene. The results from Northern blots showed that both F9 and P19 cells respond in the expected manner to a heat shock. Hsp68 expression was only detected in heat-induced F9 and P19 cells. Hsc70 transcripts were present in uninduced cells and their levels increased after induction. In adult tissues, the hsp68 gene was expressed constitutively in the kidney. A different hsp68-like transcript was detected at significant levels in adult testes. Constitutive expression of hsp68 was observed in both the placenta (beginning at Day 8.5) and yolk sac (beginning at Day 11.5). No hsp68 expression was detected in embryonic tissues until Day 15.5. Expression of the mouse hsp68 gene during embryogenesis suggests that it may play some role in development.

Animals↗

PubMed1985

Insertion of a bacterial gene into the mouse germ line using an infectious retrovirus vector.

Using a Moloney leukemia virus vector containing the bacterial neo gene, we demonstrate that retrovirus vectors can be used to introduce genes into the mouse germ line. Infection of preimplantation embryos with the vector MLV-NEO.1 resulted in integration of neo sequences in approximately equal to 10% of the progeny mice. One of these animals, mouse F.2, contained approximately six MLV-NEO.1 proviruses at independent integration sites, each present at less than a single copy per cell. This mosaic mouse transmitted one of these proviruses to her offspring, producing a line of transgenic mice carrying a full-length, unrearranged MLV.NEO.1 provirus at a single chromosomal integration site. Mice homozygous at this MLV-NEO.1 locus have also been produced. No expression of the neo gene has been detected in the transgenic mice, either by screening of primary bone marrow or lung cells for resistance to G418 or by RNA transfer blot analysis of RNA from several tissues. In addition, the neo gene was found to be extensively methylated in the transgenic mice; however, treatment of primary cells with 5-azacytidine did not induce G418 resistance. The inactivity of the MLV-NEO.1 provirus in transgenic mice and potential means of eliciting neo expression under these conditions are discussed.

Animals↗

PubMedDate not supplied

Dystonin transcripts are altered and their levels are reduced in the mouse neurological mutant dt24J.

Dystonia musculorum is a hereditary mouse neurodegenerative disorder that primarily affects the sensory arm of the nervous system. We have recently cloned and identified a candidate gene for this disorder and designated it dystonin. The sequence of dystonin predicts a rod-shaped cytoskeletal-associated protein with an actin-binding domain at the N-terminal end and a hemidesmosomal protein sequence (bpag1) at the C-terminal end. Here we show that abnormal dystonin transcripts are present in neural tissues of a spontaneous dystonia musculorum mutant, dt24J. We further show that dystonin transcript levels are reduced 2- to 3-fold in dt24J mice.

Animals↗