Chiasma interference in mosquitoes

Karyological Studies on four Species ofAnophelesSubgenusCellia

“…This agrees with the results of CALLAN and MoNTALENTI (1947) in Culex pipiens and AKSTEIN ( 1962) in Aedes aegypti. The sex-bivalent is the shortest and no staining differentiation has been observed.…”

Crossing over in Culex pipiens fatigans translocation heterozygotes

“…The sex chromosomes are homologous in Culex (Stevens, 1911;Moffett, 1936;Callan and Montalenti, 1947;Gilchrist and Haldane, 1946;Kitzmiller, 1953;Mukherjee et a!., 1970;Laven eta!., 1971) and crossing over is basically possthle in all three chromosome pairs. According to Haldane (1946, 1947) sex determination is monogenic in Culex: males are heterozygous for the male-determining dominant and the female-determining recessive allele (M/rn), while females are rn/rn; the chromosome carrying the gene has been designated I.…”

“…THE frequency of crossing over and chiasmata in European strains of Culex pipiens L. is low (Moffett, 1936;Callan and Montalenti, 1947) when compared with many other species. In translocation lines, crossovers have either not been detected at all (Laven eta!., 1971;Jost and Laven, 1971) or only at low frequencies (Dennhöfer, 1975); when occurring at higher frequencies, as in the subspecies C. p. fatigans, they are limited to the autosomes (Bhalla eta!., 1974).…”

A polymorphic centric fusion enhances chiasma interference in Leptysma argentina (Orthoptera): a chiasma distribution study

“…However, in our opinion, the overwhelming number of species with fixed fusions where chiasma studies were carried out (Callan & Montalenti, 1947;John & Lewis, 1965;Southern, 1967a;John & Freeman, 1975;Hultén, 1974;Shaw & Knowles, 1976;Maudlin & Evans, 1980;Laurie & Jones, 1981;Coates & Shaw, 1982 (see Sybenga, 1975 andJones, 1987 for a review) provides more significant evidence. None of these studies revealed such an extensive repatterning (virtual proximal and interstitial chiasma suppression) as that observed in polymorphic fusions, probably because they do not 'need' a stable trivalent orientation (albeit in some cases a slight restriction in chiasma frequency and/or position was noticed -possibly explainable in terms of across-centromere interference or pairing disturbance).…”

“…Hultén, 1974;Arana, et a!., 1980;Colombo, 1987Colombo, , 1990b accepted uncritically this point of view. However, the operation of interference across the centromere has been demonstrated in several organisms, such as Culex pipiens (Callan & Montalenti, 1947), Dicranomya trinotata, Forficularia auricularia and Asellus aquaticus (John & Lewis, 1965) and thereafter in the grasshopper Chorthippus brunneus (Laurie, 1980), where it was apparent that chiasma position in one arm of the metacentric influenced chiasma position in the other. To clarify this point, Southern (1967a) studied the correlation between chiasma frequency in the long arm vs. chiasnia frequency in the short arm in four species of 'truxaline' grasshopper (whose chromosome pairs 1 to 3 are metacentric).…”