PubMed · 7569992
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M V Olson. 1995-10-20. A time to sequence.. https://doi.org/10.1126/science.270.5235.394
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Hippophae rhamnoides ssp. turkestanica, a subdioecious plant inhabiting the cold desert of the Indian Himalaya, has gained immense recognition for its nutritional and medicinal values. In recent years, the plant species has proven to be a suitable system to understand the evolution of dioecy. Despite its biological significance, the cytogenetics of this dioecious plant is unclear due to various conflicting accounts of its X-Y chromosome system, particularly the length of Y-chromosome. In this study, we resolved these ambiguities through comprehensive cytogenetic analyses across diverse western Himalayan populations. Using morphometric analysis and fluorescence in situ hybridization (FISH) with a gender-specific marker (HRMSSR), we confirmed homomorphic XX chromosomes in females and heteromorphic sex-chromosomes in males with a notably smaller Y-chromosome. The investigation also revealed a predominant somatic chromosome number of 2n = 24, although minor deviations (2n = 18, 20, 22) appeared at the seed level. These findings highlight an evolutionarily advanced sex-chromosome system. This first detailed cytogenetic investigation of Himalayan Seabuckthorn provides critical insights into the chromosomal architecture, laying a crucial foundation for future evolutionary, genomic, and conservation studies in the species.
Parkinson's disease (PD) is the second most common neurodegenerative disorder after Alzheimer's disease, affecting approximately 1 percent of the population over age 50. Recent studies have confirmed significant familial aggregation of PD and a large number of large multicase families have been documented. Genetic markers on chromosome 4q21-q23 were found to be linked to the PD phenotype in a large kindred with autosomal dominant PD, with a Zmax = 6.00 for marker D4S2380. This finding will facilitate identification of the gene and research on the pathogenesis of PD.
BACKGROUND: Frequent allelic losses on the long arm of chromosome 13 in sporadic breast carcinomas suggest that a tumor suppressor gene(s) on 13q is involved in this type of carcinoma. The presence of a familial breast carcinoma susceptibility gene, BRCA2, and the retinoblastoma susceptibility gene (RB) on the same chromosomal arm implies that one or the other, or both, of these genes may be critically affected by those allelic losses. METHODS: To investigate the possible involvement of BRCA2 and RB in sporadic breast carcinomas, the authors examined allelic losses in 246 breast carcinomas with 14 polymorphic microsatellite markers on 13q12.q14. RESULTS: Allelic loss was observed in 95 of the 246 sporadic breast carcinomas (39%). Detailed deletion mapping identified two commonly deleted regions. The more proximal of these two segments was located in a 6-cM interval flanked by marker loci D13S289 and D13S267 and containing the BRCA2 gene; the more distal region was located in a 9-cM interval flanked by marker loci D13S328 and D13S172 and containing the RB gene. Allelic loss on 13q was found more frequently in tumors of the solid tubular histologic type (36 of 66; 55%) than in other types (52 of 146; 36%) (P = 0.0096). Furthermore, a significant association was observed between allelic loss on 13q and the absence of progesterone receptor (P = 0.0001). CONCLUSIONS: The results indicate that BRCA2 and RB are independent targets of allelic loss and that inactivation of either of these genes may play a role in the development of some sporadic breast carcinomas, particularly those of the solid tubular type.