THE NATURE OF GENETIC RECOMBINATION NEAR THE THIRD CHROMOSOME CENTROMERE OF DROSOPHILA MELANOGASTER

Abstract

Previous studies have indicated that recombination near the third chromosome centromere is associated with negative chromosome interference, a phenomenon for which GREEN (1975) and SINCLAIR (1975) suggested gene conversion as a possible mechanism. In this report, we demonstrate that negative chromosome interference is still observed when deficiencies or translocation breakpoints are scored as the middle markers in recombination experiments and the rate of recombination is increased by interchromosomal effect. We argue that these chromosomal rearrangement breakpoints are not subject to conversion. Since neither successive premeiotic and meiotic exchanges, nor negative chromatid interference, can by themselves account for the negative chromosome interference, we conclude that a greater than expected frequency of multiple exchanges actually occurs. We further suggest that negative chromosome interference may be characteristic of all chromosomal regions normally showing very little exchange in relation to physical length.

Background selection and patterns of genetic diversity inDrosophila melanogaster

“…The mapping function of eqn ( 4) is used to describe recombination within chromosome arms. The coefficient of coincidence across the centromere for autosomal regions close to the centromere is assumed to be 10, in rough accordance with published estimates (Green, 1975;Sinclair, 1975;Denell & Keppy, 1979). The other recombination parameters are as in Table 1-3.…”

“…For the metacentric chromosomes 2 and 3, there is strong negative interference across the centromere between intervals which are very close to the centromere, whereas there is no such effect between more distal regions (Ashburner, 1989, p. 470). Thus, although an exchange near the centromeric heterochromatin is a rare event, the conditional probability of a proximal exchange in one arm of an autosome may be increased by a factor of 10 or more by the occurrence of a proximal exchange in the other arm (Green, 1975;Sinclair, 1975;Denell & Keppy, 1979). The above mapping function thus cannot be used for determining the frequency of recombination between an autosomal marker locus and a selected locus on a different arm of the same chromosome.…”

Statistical analysis and simulation allowing simultaneously positive, negative, and no crossover interference in multilocus recombination data

“…Thus, the resulting "gamma-sprinkled" (GS) model assumes a mixture of gamma distributions with v>1 and v=1 (cases of positive COI and no COI) with proportions 1-p and p, respectively, and appeared to be more consistent with empirical data [32]. Yet, cases of possible negative COI were also reported on different organisms (Neurospora, yeast, Drosophila, Arabidopsis, maize, barley, wheat), and the possible presence of CO clustering effect (negative COI) was reported [1,2,33,35,38,3,4,7,8,11,[14][15][16] When applied to such cases, the GS-model gives biased estimates of both parameters, p, and v, due to the presence of three components (with v>1, v=1, and v<1). Therefore, to take account of possible negative interference, we extend the GS model by fitting a mixture of the corresponding three distributions.…”

Predicting recombination suppression outside chromosomal inversions in Drosophila melanogaster using crossover interference theory

“…Negative crossover interference is the uncommon observation of an increased, rather than decreased, probability of crossing-over in an interval given a crossover event nearby. Negative crossover interference is rarely incorporated into mapping functions; however, its presence at D. melanogaster centromeres and associate pericentric heterochromatin has been reproducibly observed and extensively documented (Morgan et al 1925;Green 1975;Sinclair 1975;Denell and Keppy 1979).…”

“…In D. melanogaster, crossing-over on one euchromatic arm of a metacentric chromosome does not generally alter the probability of observing crossover events for the other euchromatic arm (Muller 1916;Graubard 1934;Stevens 1936;Miller et al 2016a); however, when relatively rare pericentromeric crossover events occur on one arm there is, paradoxically, an increased probability of crossing-over in the opposite arm's pericentromeric region (Morgan et al 1925;Green 1975;Sinclair 1975;Denell and Keppy 1979). This effect can be quite strong, with empirical coefficients of coincidence exceeding unity by several orders of magnitude, causing correspondingly negative values for strength of inference.…”