title: Possible autosomal origin of macro B chromosomes in two grasshopper species.
abstract: The acrocentric macro B chromosomes of Rhammatocerus brasiliensis (Acrididae, Gomphocerinae) and Xyleus discoideus angulatus (Romaleidae, Romaleinae) are highly similar to the X chromosome in each species in terms of morphology, size, and pycnosis. However, the results of FISH experiments using 45S and 5S rDNA probes suggest that in both species the B chromosomes are most likely of autosomal origin. In R. brasiliensis, the B chromosome presented 5S rDNA but not 45S rDNA, in resemblance to the L(2), L(3), M(5) and S(11) autosomes, but the X chromosome lacks both rDNA families. In X. d. angulatus, 45S rDNAs is absent from the B chromosome, whereas the X chromosome contains one of the two 45S rDNA clusters in the genome. The occurrence of B chromosomes in all nine R. brasiliensis populations analyzed indicates that they are widely distributed in Northeastern Brazil, and the small amount of interpopulation variation found for B chromosome prevalence suggests the existence of high gene flow, presumably due to the abundance of this grasshopper species on several types of vegetation and its relatively high flight capability.
authors: Unidade Acadêmica de Garanhuns, Universidade Federal Rural de Pernambuco, Recife, PE, Brazil. vloreto@bol.com.br
authors: Vilma
authors: V
authors: Loreto
authors: Josefa
authors: J
authors: Cabrero
authors: Maria Dolores
authors: MD
authors: López-León
authors: Juan Pedro M
authors: JP
authors: Camacho
authors: Maria José
authors: MJ
authors: Souza
mesh_terms: D000818:Animals; D002875:Chromosomes / Q000737:chemistry / Q000502:physiology*; D005260:Female; D049810:Genetic Speciation; D006110:Grasshoppers / Q000235:genetics*; D007621:Karyotyping; D008297:Male