scholarly journals Centromere-proximal meiotic crossovers in Drosophila melanogaster are suppressed by both highly-repetitive heterochromatin and the centromere effect

2019 ◽  
Author(s):  
Michaelyn Hartmann ◽  
James Umbanhowar ◽  
Jeff Sekelsky
Keyword(s):  
Drosophila Melanogaster ◽  
Low Frequency ◽  
Heterochromatic Region ◽  
Bloom Syndrome ◽  
Segregation Of Chromosomes

AbstractCrossovers are essential in meiosis of most organisms to ensure the proper segregation of chromosomes. The lack or improper placement of crossovers can result in nondisjunction and aneuploidy in progeny. Crossovers near the centromere can cause nondisjunction; centromere-proximal crossovers are suppressed by what is termed the centromere effect, but the mechanism is unknown. Here, we investigate contributions to centromere-proximal crossover suppression in Drosophila melanogaster. We mapped a large number of centromere-proximal crossovers and find that crossovers are essentially absent from the highly-repetitive (HR)-heterochromatin surrounding the centromere but occur at a low frequency within the less-repetitive (LR)-heterochromatic region and adjacent euchromatin. Previous research suggested that flies that lack the Bloom syndrome helicase (Blm) lose meiotic of crossover patterning, including the centromere effect. Mapping of centromere-proximal crossovers in Blm mutants reveals that the suppression within the HR-heterochromatin is intact, but the centromere effect is lost. We conclude that centromere-proximal crossovers are suppressed by two separable mechanisms: the HR-heterochromatin effect, which completely suppresses crossovers in the HR-heterochromatin, and the centromere effect, which suppresses crossovers with a dissipating effect with distance from the centromere.

scholarly journals GENETIC ANALYSIS OF THE CENTROMERIC HETEROCHROMATIN OF CHROMOSOME 2 OF DROSOPHILA MELANOGASTER: DEFICIENCY MAPPING OF EMS-INDUCED LETHAL COMPLEMENTATION GROUPS

Genetics ◽  
1976 ◽  
Vol 83 (4) ◽  
pp. 765-782
Author(s):  
Arthur J Hilliker
Keyword(s):  
Drosophila Melanogaster ◽  
Present Report ◽  
Heterochromatic Region ◽  
Centromeric Heterochromatin ◽  
Genetic Constitution ◽  
Genetic Dissection ◽  
Chromosome 2 ◽  
Multiple Alleles ◽  
Products Analysis ◽  
Dominance Tests

ABSTRACT Until recently, little was known of the genetic constitution of the heterochromatic segments of the major autosomes of Drosophila melanogaster. Our previous report described the genetic dissection of the proximal, heterochromatic region of chromosome 2 of Drosophila melanogasterby means of a series of overlapping deficiencies generated by the detachment of compound second autosomes (Hilliker and Holm 1975). Analysis of these deficiencies by inter se complementation, pseudo-dominance tests with proximal mutations and allelism tests with known deficiencies provided evidence for the existence of at least two loci between the centromere and the light locus in 2L and one locus in 2R between the rolled locus and the centromere. These data in conjunction with cytological observations demonstrated that light and rolled and three loci lying between them are located within the proximal heterochromatin of the second chromosome.——The present report describes the further analysis of this region through the induction with ethyl methanesulphonate (EMS) of recessive lethals allelic to the 2L and 2R proximal deficiencies associated with the detachment products. Analysis of the 118 EMS-induced recessive lethals and visible mutations recovered provided evidence for seven loci in the 2L heterochromatin and six loci in the 2R heterochromatin, with multiple alleles being obtained for most sites. Of these loci, one in 2L and two in 2R fall near the heterochromatic-euchromatic junctions of 2L and 2R respectively. None of the 113 EMS lethals behaved as a deficiency, implying that the heterochromatic loci uncovered in this study represent nonrepetitive cistrons. Thus functional genetic loci are found in heterochromatin, albeit at a very low density relative to euchromatin.

scholarly journals Cuticular Hydrocarbon Content that Affects Male Mate Preference of Drosophila melanogaster from West Africa

2012 ◽  
Vol 2012 ◽  
pp. 1-10 ◽  
Author(s):  
Aya Takahashi ◽  
Nao Fujiwara-Tsujii ◽  
Ryohei Yamaoka ◽  
Masanobu Itoh ◽  
Mamiko Ozaki ◽  
...  
Keyword(s):  
Drosophila Melanogaster ◽  
Low Frequency ◽  
Cuticular Hydrocarbon ◽  
Inhibitory Effect ◽  
Incipient Speciation ◽  
Transfer Experiment ◽  
Premating Isolation ◽  
Potential Factor ◽  
Male Mate ◽  
Different Strains

Intraspecific variation in mating signals and preferences can be a potential source of incipient speciation. Variable crossability between Drosophila melanogaster and D. simulans among different strains suggested the abundance of such variations. A particular focus on one combination of D. melanogaster strains, TW1(G23) and Mel6(G59), that showed different crossabilities to D. simulans, revealed that the mating between females from the former and males from the latter occurs at low frequency. The cuticular hydrocarbon transfer experiment indicated that cuticular hydrocarbons of TW1 females have an inhibitory effect on courtship by Mel6 males. A candidate component, a C25 diene, was inferred from the gas chromatography analyses. The intensity of male refusal of TW1 females was variable among different strains of D. melanogaster, which suggested the presence of variation in sensitivity to different chemicals on the cuticle. Such variation could be a potential factor for the establishment of premating isolation under some conditions.

Genetic Effects of Low Frequency Stress on Drosophila melanogaster

1971 ◽  
Vol 62 (3) ◽  
pp. 157-160 ◽  
Author(s):  
F. P. SAITTA ◽  
J. W. CRENSHAW
Keyword(s):  
Drosophila Melanogaster ◽  
Low Frequency ◽  
Genetic Effects

scholarly journals Abnormal meiotic spindles cause a cascade of defects during spermatogenesis in asp males of Drosophila

Development ◽  
1990 ◽  
Vol 108 (2) ◽  
pp. 251-260
Author(s):  
J. Casal ◽  
C. Gonzalez ◽  
F. Wandosell ◽  
J. Avila ◽  
P. Ripoll
Keyword(s):  
Drosophila Melanogaster ◽  
Variable Size ◽  
Meiotic Spindles ◽  
Spindle Structure ◽  
Size Of Nuclei ◽  
Segregation Of Chromosomes

Since spermatogenesis in Drosophila is a series of interconnected and interdependent steps and most of the spermatogenic events take place in the absence of transcription, failures in a given stage can give rise to a cascade of defects later on. The asp locus of Drosophila melanogaster codes for a non-tubulin component implicated in proper spindle structure and/or function (Ripoll et al. 1985). Homozygous asp males exhibit abnormal meiotic spindles giving rise to altered segregation of chromosomes and mitochondria and failures in cytokinesis. Postmeiotic spermatogenic stages of asp males show a series of alterations that we interpret as due to the previously occurring defective meiosis because meiotic spindles are the only microtubular structure altered in mutant testes. The most conspicuous alterations are: (i) variable size of nuclei and nebenkerns of early spermatids, which are also multinucleate instead of having single and uniformly sized nuclei; (ii) elongating spermatids in which abnormal-sized mitochondrial derivatives elongate alongside more than one axoneme; (iii) failures in the individualization process, where abnormal spermatids remain syncytial, and seem to be eliminated during the coiling stage.

scholarly journals Inferring the evolutionary histories of the Adh and Adh-dup loci in Drosophila melanogaster from patterns of polymorphism and divergence.

Genetics ◽  
1991 ◽  
Vol 127 (3) ◽  
pp. 565-582 ◽  
Author(s):  
M Kreitman ◽  
R R Hudson
Keyword(s):  
Drosophila Melanogaster ◽  
Dna Sequences ◽  
Natural Populations ◽  
Low Frequency ◽  
Amino Acid Replacement ◽  
Graphical Analysis ◽  
Recombination Suppression ◽  
Balanced Polymorphism ◽  
Selective Substitution ◽  
Flanking Region

Abstract The DNA sequences of 11 Drosophila melanogaster lines are compared across three contiguous regions, the Adh and Adh-dup loci and a noncoding 5' flanking region of Adh. Ninety-eight of approximately 4750 sites are segregating in the sample, 36 in the 5' flanking region, 38 in Adh and 24 in Adh-dup. Several methods are presented to test whether the patterns and levels of polymorphism are consistent with neutral molecular evolution. The analysis of within- and between-species polymorphism indicates that the region is evolving in a nonneutral and complex fashion. A graphical analysis of the data provides support for a hypothesized balanced polymorphism at or near position 1490, site of the amino acid replacement difference between Adhf and Adhs. The Adh-dup locus is less polymorphic than Adh and all 24 of its polymorphisms occur at low frequency--suggestive of a recent selective substitution in the Adh-dup region. Adhs alleles form two distinct evolutionary lineages that differ one from another at a total of nineteen sites in the Adh and Adh-dup loci. The polymorphisms are in complete linkage disequilibrium. A recombination experiment failed to find evidence for recombination suppression between the two allelic classes. Two hypotheses are presented to account for the widespread distribution of the two divergent lineages in natural populations. Natural selection appears to have played an important role in governing the overall patterns of nucleotide variation across the two-gene region.

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