Interference relationships in grasshopper reciprocal translocation heterozygotes

Abstract

Chiasma formation in four different reciprocal translocations in the grasshopper Eyprepocnemis plorans (2nd =22 + X) is analysed using C-banding. A given chromosome involved in an interchange is sometimes identifiable in standard homozygotes so that changes in its formation of chiasmata may be estimated. The involvement of M9 chromosome in an interchange slightly reduces its mean chiasma frequency but interference is significatively reduced too. When interference relationships between arms are analysed in the interchanges, independence as well as interference may occur, the interference being positive between adjacent arms and negative between opposite arms. A parallel analysis at pachytene reveals synaptic failure affecting mainly small regions. These results are discussed under Sybenga's (1970) model for interference relationships within quadrivalents.

What makes homologous chromosomes find each other in meiosis? A review and an hypothesis

“…In translocation heterozygotes the translocation break caused an interruption of homology, but quadrivalents were formed, indicating that the end normally not initiating pairing was quite capable of doing so when the normally active end was separated from it by an interruption in homology. This agrees with the observations of Arana et al (1987) and Parker (1987) on translocation heterozygotes in insects as well as in plants. Chiasma interference is generally suspended by interruptions in the SC, for instance in asynaptics, in which short isolated SC segments are formed (Havekes et al 1993;Sybenga 1996).…”

Comparative cytogenetic analysis of two grasshopper species of the tribe Abracrini (Ommatolampinae, Acrididae)

“…In contrast, more recent fusions and polymorphisms in this type of chromosomal rearrangement have been observed in grasshoppers such as Cornops aquaticum (Mesa et al , 1982), Eyprepocnemis plorans (Arana et al , 1987), Leptysma argentina (Colombo, 1993) and Dichroplus pratensis (Bidau and Martí, 2002). …”

Cytogenetics in Plant Breeding

“…It then results in an increase in the probability of chiasma formation in chromosome segments that without the translocation do not have a chiasma (Parker 1987: the plant species Hypochoeris; Arana et al 1987: the grasshopper Eyprepocnemis). Changes in interference relations, due to the special spatial relations between the pairing chromosomes around the point of pairing partner ex-change.…”