نتایج جستجو برای: b chromosome
تعداد نتایج: 1002957 فیلتر نتایج به سال:
Supernumerary or B chromosomes are selfish entities that maintain themselves in populations by accumulation mechanisms. The accumulation mechanism of the B chromosome of maize (Zea mays) involves nondisjunction at the second pollen mitosis, placing two copies of the B chromosome into one of the two sperm. The B chromosome long arm must be present in the same nucleus for the centromere to underg...
Supernumerary (B) chromosomes have been shown to contain a wide variety of repetitive sequences. For this reason, fluorescent in situ hybridisation (FISH) is a useful tool for ascertaining the origin of these genomic elements, especially when combined with painting from microdissected B chromosomes. In order to investigate the origin of B chromosomes in the fish species Astyanax paranae, these ...
Supernumerary (B) chromosomes are dispensable elements found in many eukaryote genomes in addition to standard (A) chromosomes. In many respects, B chromosomes resemble sex chromosomes, so that a common ancestry for them has frequently been suggested. For instance, B chromosomes in grasshoppers, and other insects, show a pycnotic cycle of condensation-decondensation during meiosis remarkably si...
Maize B-A translocations result from reciprocal interchanges between a supernumerary B chromosome and an arm of an essential A chromosome. Because of the frequent nondisjunction of the B centromere at the second pollen mitosis, B-A translocations have been used to locate genes to chromosome arms and to study the dosage effects of specific A segments. Compound B-A translocations (B-A-A transloca...
eleven populations of five avena species were analysed for meiotic characters including chiasma frequency and distribution as well as chromosomal association and segregation. plants of a single population of a. eriantha showed the presence of 2n = 14 (diploid) and 2n = 4x = 28 chromosome number. populations of a. barbata and a. wiestii possessed n = 14, while populations of a. sterilis ssp. lud...
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