PubMed · 4613607
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R D Hotchkiss. 1974. Molecular basis for genetic recombination.. https://doi.org/10.1093/genetics%2F78.1.247
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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.
A genome-wide linkage scan for endurance training-induced changes in submaximal exercise stroke volume (DeltaSV50) in the HERITAGE Family Study revealed two chromosomal regions (2q31-q32 and 10p11.2) with at least suggestive evidence of linkage among white families. Here we report a further characterization of the quantitative trait locus (QTL) in chromosome 2q31 and provide evidence that titin (TTN) is likely a candidate gene involved. The original linkage was detected with two markers (D2S335 and D2S1391), and the QTL covered approximately 25 million base pairs (Mb). We added 12 microsatellite markers resulting in an average marker density of one marker per 2.3 Mb. The evidence of linkage increased from P = 0.006 to P = 0.0002 and 0.00002 in the multi- and single-point analyses, respectively. The strongest evidence of linkage was seen with two markers in and near the TTN gene. Transmission/disequilibrium test (TDT) with the same marker set provided evidence for association with one of the TTN markers (D2S385; P = 0.004). TTN is a major contributor to the elasticity of cardiomyocytes and a key regulator of the Frank-Starling mechanism. Since TTN is the largest gene in the human genome, the challenge is to identify the DNA sequence variants contributing to the interindividual differences in cardiac adaptation to endurance training.
Parietal foramina [PFM], inherited usually in an autosomal dominant mode, is an extremely rare developmental defect characterized by a symmetrical, oval hole in the parietal bone. It can be present as either an isolated or a syndromic feature. PFM types 1 and 2 (PFM1 and PFM2) have been found to be caused by mutations in the MSX2 and ALX4 genes, located to chromosomes 5 and 11, respectively. After exclusion of both the above loci in a large Chinese pedigree with autosomal dominant PFM, a genome-wide search revealed a linkage of the PFM to markers at the 4q21-q23 region. The maximum LOD score from two-point linkage analysis is 3.87 for marker D4S2961. Analysis of co-segregated haplotype localized the region to a 20-cM interval that flanks D4S392 and D4S2945. Therefore, we concluded that the PFM in the family is a new PFM locus. Although three genes, BMPR1B, PP1 and IBSP, are located to 4q21-q25 and their functions are related to bone morphogenesis, no mutations were identified by sequencing analysis of their exons.