Metaphase I orientation of Robertsonian trivalents in the water-hyacinth grasshopper, Cornops aquaticum (Acrididae, Orthoptera)

• Autores: Colombo, P.C.
• Año de publicación: 2009
• Idioma: inglés
• Tipo de recurso: artículo
• Fuente: Genet. Mol. Biol. 2009;32(1):91-95
• Materia: Cornops aquaticum; Metaphase I orientation; Robertsonian rearrangements; Trivalents; anaphase; animal tissue; article; chromosome rearrangement; Cornops aquaticum; correlation analysis; cytogenetics; enzyme polymorphism; heterozygosity; male; metaphase; molecular evolution; nonhuman; Orthoptera; Robertsonian rearrangement; spermatid; Acrididae; Cornops; Cornops aquaticum; Eichhornia crassipes; Orthoptera; Robertsonia; Schistocerca americana
• Institución: Universidad Nacional de Buenos Aires. Facultad de Ciencias Exactas y Naturales

Trivalents resulting from polymorphic Robertsonian rearrangements must have a regular orientation in metaphase I if the polymorphisms are to be maintained. It has been argued that redistribution of proximal and interstitial chiasmata to more distal positions is necessary for a convergent orientation, the only one that produces viable gametes. Cornops aquaticumis a South-American grasshopper that lives and feeds on water-hyacinths, and has three polymorphic Robertsonian rearrangements in its southernmost distribution area in Central Argentina and Uruguay. The orientation of trivalents in metaphase I, the formation of abnormal spermatids and the frequency and position of chiasmata in the trivalents, was analysed in a polymorphic population of C. aquaticus. In this study we observed a correlation between the number of trivalents with the frequency of abnormal spermatids; additionally, the number of chiasmata, especially proximal and interstitial ones, was strongly correlated with the frequency of the linear orientation. Therefore we confirmed our previous assumption, based on other evidence, that the chiasmata redistribution in fusion carriers is essential to the maintenance of the polymorphisms. Copyright © 2009, Sociedade Brasileira de Genética.
Fil:Colombo, P.C. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.