in this study, for the first time in iran, the karyotype of bigmouth lotak, cyprinion macrostomum heckel, 1843, was investigated through examining metaphase chromosomes of seven fish with mean weight 30±5g caught by electrofishing from godarkhosh river in ilam province. to stimulate cell divisions, fish were injected intraperitoneally two times by phytohemagglutinin (pha). the cell divisions we...

eight accessions of thyme medicinal plant, belonging to iranian endemic thymus daënensis, t. eriocalyx, t. migricus and an unknown thymus spp species, were tested for karyotypic analysis, using squash technique and 2% (w/v) aceto-orcein staining method. chromosomal parameters examined were: short arm (s), long arm (l), total length of chromosome (tl), arm ratio (ar), r-value, total chromosome v...

Every eukaryotic chromosome has a centromere, the locus responsible for poleward movement at mitosis and meiosis. Although conventional loci are specified by their DNA sequences, current evidence favors a chromatin-based inheritance mechanism for centromeres. The chromosome segregation machinery is highly conserved across all eukaryotes, but the DNA and protein components specific to centromeri...

During meiosis, the formation of viable haploid gametes from diploid precursors requires that each homologous chromosome pair be properly segregated to produce an exact haploid set of chromosomes. Genetic recombination, which provides a physical connection between homologous chromosomes, is essential in most species for proper homologue segregation. Nevertheless, recombination is repressed spec...

Centromere protein B, which is involved in centromere formation, binds to centromeric repetitive DNA by recognizing a nucleotide motif called the CENP-B box. Humans have large numbers of CENP-B boxes in the centromeric repetitive DNA of their autosomes and X chromosome. The current understanding is that these CENP-B boxes are located at identical positions in the repeat units of centromeric DNA...

Centromeres, because of their repeat structure and lack of sequence conservation, are difficult to assemble and compare across organisms. It was recently discovered that rice centromeres often contain genes. This suggested a method for studying centromere homologies between wheat and rice chromosomes by mapping rice centromeric genes onto wheat aneuploid stocks. Three of the seven cDNA clones o...