title: Achiasmate segregation of X and B univalents in males of the grasshopper Eyprepocnemis plorans is independent of previous association.
abstract: B chromosomes proved to be more frequent in males than females of the grasshopper Eyprepocnemis plorans collected from the population in Jete (Granada, Spain) in 1992. The meiotic behaviour of the X and B univalents was analysed in a high number of 1B males collected from this population in 1991 and 1992, and in males from another population (Salobreña, Granada, Spain) for comparison. These two chromosomes showed a significant tendency to migrate to opposite poles in the Jete population, during the 2 years analysed, but separated randomly in the Salobreña population. Thus, sex differences in the B frequency in Jete seemed to be due to the non-random X-B segregation during male meiosis. The analysis of association patterns between the two univalents over several stages of the first meiotic division indicated a heterochromatic affinity rather than association by chiasmata because most X-B associations had resolved by metaphase I. The X and B chromosomes share two different DNA sequences, so that some associations during prophase I undoubtedly involve homologous DNA sequences. The frequency with which X and B migrated to opposite poles at anaphase I in Jete, however, did not show any significant dependence on previous association at zygotene, diplotene or metaphase I.
authors.affiliation: Departamento de Genética, Universidad de Granada, Spain.
authors.forename: M D
authors.initials: MD
authors.lastname: López-León
authors.forename: J
authors.initials: J
authors.lastname: Cabrero
authors.forename: J P
authors.initials: JP
authors.lastname: Camacho
mesh_terms: D000705:Anaphase; D000818:Animals; D002842:Chromatids / Q000737:chemistry; D002843:Chromatin / Q000737:chemistry; D002875:Chromosomes; D005260:Female; D006110:Grasshoppers / Q000235:genetics*; D008297:Male; D008540:Meiosis; D008677:Metaphase; D012689:Sequence Homology, Nucleic Acid; D012730:Sex Chromosomes; D014960:X Chromosome
chemical_list: D002843:Chromatin