A comparative cytogenetic analysis between the grasshopper species Chromacris nuptialis and C. speciosa (Romaleidae): constitutive heterochromatin variability and rDNA sites.
The chromosomes of Chromacris nuptialis and C. speciosa were comparatively analyzed using different cytogenetic techniques, in order to determine the level of karyotypic similarities and differences between the species. The results show similarities in chromosome number (2n=23,X0) and acrocentric morphology. In some C. nuptialis individuals meiotic irregularities were detected involving the L(2) bivalent. This bivalent was delayed and presented anaphasic bridges and other aberrations. Differences in constitutive heterochromatin (CH) patterns and composition were observed through C-banding and fluorochromes staining. Silver nitrate staining revealed a single medium nucleolar organizer regions (NORs) pair, per species. Differences were also observed in NORs location, which was pericentromeric in C. nuptialis and proximal in C. speciosa. FISH using an rDNA probe confirmed the existence of ribosomal sites coinciding with active regions visualized by silver nitrate. The possible implications of the karyotype differences observed between both species are discussed.
Loreto
Vilma
V
Departamento de Genética, CCB, Universidade Federal de Pernambuco, Brasil. vloreto@zipmail.com.br
Stadtler
Eva
E
de Melo
Natoniel F
NF
de Souza
Maria José
MJ
D000818:Animals; D002871:Chromosome Banding; D002875:Chromosomes / Q000235:genetics; D003582:Cytogenetics; D004275:DNA, Ribosomal / Q000235:genetics; D005260:Female; D014644:Genetic Variation; D006110:Grasshoppers / Q000145:classification / Q000235:genetics*; D006570:Heterochromatin / Q000235:genetics; D017404:In Situ Hybridization, Fluorescence; D007621:Karyotyping; D008297:Male; D013045:Species Specificity
D004275:DNA, Ribosomal; D006570:Heterochromatin