PubMed · 6400657
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R L White. Mapping human chromosomes.. https://pubmed.ncbi.nlm.nih.gov/6400657/
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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.
In paternity testing using the DNA evidence, analysis of the deficiency case when the DNA profiles of the alleged father are not available is different from that of the case with complete evidence. In this paper, we describe how to evaluate and determine the paternity in the deficiency case, by comparing the paternity indexes of the true father and the falsely non-excluded man.
Meiotic recombination in the yeast Saccharomyces cerevisiae is initiated by programmed double-strand breaks at selected sites throughout the genome (hotspots). alpha-Hotspots are binding sites for transcription factors. Double-strand breaks at alpha-hotspots require binding of transcription factor but not high levels of transcription per se. We show that modulating the production of the transcription factor Gcn4p by deletion or constitutive transcription alters the rate of gene conversion and crossing-over at HIS4. In addition, we show that alterations in the metabolic state of the cell change the frequency of gene conversion at HIS4 in a Gcn4p-dependent manner. We suggest that recombination data obtained from experiments using amino acid and other biosynthetic genes for gene disruptions and/or as genetic markers should be treated cautiously. The demonstration that Gcn4p affects transcription of more than 500 genes and that the recombinationally "hottest" ORFs tend to be Gcn4p-regulated suggest that the metabolic state of a cell, especially with respect to nitrogen metabolism, is a determinant of recombination rates. This observation suggests that the effects of metabolic state may be global and may account for some as yet unexplained features of recombination in higher organisms, such as the differences in map length between the sexes.