October 7, 2011
Chromosome Inheritance? Not The Same For All The Chromosomes
New findings of researchers from the University of Modena and Reggio Emilia (Mauro Mandrioli, Valentina Monti and Gian Carlo Manicardi) show that in aphids the two X chromosomes have a different inheritance. The study was published in Comparative Cytogenetics.
Aphids are insects with a sex determination model based on the presence of two X chromosomes (XX) in females and a single X chromosome (XO) in males. Previous studies suggested that X chromosome loss during male determination was random and that both X chromosomes have the same probability to be inherited in males. On the contrary, some authors suggested the presence of strong biases in the transmission of sex chromosomes, so that X chromosomes may have a non-mendelian inheritance in aphids.
X chromosomes with few rDNA genes seem to be less sticky that X chromosomes with larger rDNA regions, so that their inheritance is not random and X chromosomes with few rDNA genes may be lost and not inherited in males. Mutations in the chromosome structure could therefore affect chromosomal inheritance even if these changes do not affect regions involved in centromere functioning.
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