SOMATIC CROSSING OVER AND ITS GENETIC CONTROL IN DROSOPHILA

Papilio memnon is a swallowtail butterfly widely distributed in south-east Asia. The females are highly polymorphic and many of them are mimetic. The mode of inheritance of seventeen of the female forms is reported. In contradistinction to earlier work it has been shown that they are controlled by what appears to be a series of at least eleven autosomal alleles at one locus, sexcontrolled to the female in effect. There is evidence, however, that the locus is complex, comprising at least three closely linked loci with occasional occurrence of crossing over between them. Two characters which are not polymorphic and one which may be polymorphic are controlled by genes unlinked to the complex locus (the super-gene). In general, dominance is complete between sympatric forms but absent when they are allopatric. The resemblance between the mimetic forms of P. memnon and their models is greater in the genecomplex of a race in which the allelomorph occurs than in hybrids with a race in which it does not. Thus in no case is the resemblance better in the race cross, in ten cases there is no change and in thirty-five the mimicry is less good. The genetic control of the polymorphism in P. memnon shows remarkable parallels with that in P. dardanus and provides further supporting evidence for Fisher’s and Ford’s view that mimicry evolved gradually by adjustment of the gene-complex as a result of natural selection favouring those wing patterns which most closely resembled the models. Furthermore, as in P. dardanus, the mimicry is controlled by what appears to be a super-gene, adding weight to the conclusion that the genetic control of the polymorphic Batesian mimicry has evolved gradually by the accumulation of closely linked allelomorphs in advantageous combinations. This contrasts with the genetic control of Mullerian mimicry as evidenced in the Heliconids. In P. memnon the dominance relationships of the monomorphic tailed and tailless condition (excluding the form achates ) indicate that dominance can be evolved even when the characters concerned are not polymorphic. In addition, the lower frequency of dominance between allopatric forms than between sympatric ones is strongly in favour of the view that dominance has evolved. Similar evidence has been found from breeding work in the Heliconids and in P. dardanus ; however, the phenomenon is not confined to mimetic situations since there is also evidence for the evolution of dominance in other polymorphisms including industrial melanism.

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INCIPIENT GENOME DIFFERENTIATION IN GOSSYPIUM. I. CHROMOSOMES 14, 15, 16, 19 AND 20 ASSESSED IN G. HIRSUTUM, G. RAIMONDII AND G. LOBATUM BY MEANS OF SEVEN A-D TRANSLOCATIONS

Genetics ◽

10.1093/genetics/90.1.133 ◽

1978 ◽

Vol 90 (1) ◽

pp. 133-149

Author(s):

Margaret Y Menzel ◽

Meta S Brown ◽

Safia Naqi

Keyword(s):

Genetic Control ◽

Crossing Over ◽

Early Stages ◽

Genome Differentiation ◽

Reciprocal Exchange ◽

Whole Genomes ◽

Genome Divergence ◽

Chromosome Regions

ABSTRACT The genus Gossypium is favorable for study of genome divergence at several levels. Early stages of divergence have been studied among four D genomes by comparing chiasma frequencies (reciprocal exchanges) between pairs of genomes and between individual counterpart chromosomes marked by heterozygous translocations. D5 (G. raimondii) shows barely detectable differentiation from from Dh (G. hirsutum), whereas D7 (G. lobatum) is considerably less closely related to Dh than is D5. Fragmentary data suggest that D2-2 (G. harknessii) falls between D5 and D7 in its relationship to Dh. Since chiasma frequencies in individual chromosomes and marked regions exhibit the same order of relationships as their corresponding whole genomes, it is concluded that the genome differentiation is generalized (i.e., nucleus-wide) rather than localized in specific chromosomes or chromosome regions. Estimates of relationships based on reciprocal exchange frequencies agree with those based upon preferential synapsis in allohexaploids reported previously. Since preferential synapsis and reciprocal exchange frequencies reveal the same order of relationships, it is concluded that to some extent they reflect common underlying changes in chromosome properties, despite recent evidence that synapsis and crossing over are under independent genetic control.

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PARACENTRIC INVERSIONS AND DETECTION OF SEX LINKED RECESSIVE LETHALS IN AEDES AEGYPTI

Canadian Journal of Genetics and Cytology ◽

10.1139/g70-084 ◽

1970 ◽

Vol 12 (3) ◽

pp. 635-650 ◽

Cited By ~ 15

Author(s):

Satish C. Bhalla

Keyword(s):

Aedes Aegypti ◽

Genetic Control ◽

Chromosomal Aberrations ◽

The Other ◽

Crossing Over ◽

Partial Sterility ◽

X Irradiation ◽

Paracentric Inversions

Two sex linked paracentric inversions one on m chromosome, marked with bz (bronze body) and the other on M chromosome, marked with w (white eye), were artificially induced with X-irradiation and isolated. The inversions are designated as In. (1)1 and In. (1)2 respectively. The former is more than 23 units long and the later more than 16 units. Both suppress crossing over markedly and are associated with partial sterility. The two inversions are utilized as crossover suppressors in a technique designed for detecting sex linked recessive lethals. The technique works satisfactorily with certain limitations. The possibility of combining inversions with other chromosomal aberrations for genetic control of Aedes aegypti populations is suggested.

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Recombinationless meiosis in Saccharomyces cerevisiae

Molecular and Cellular Biology ◽

10.1128/mcb.1.10.891-901.1981 ◽

1981 ◽

Vol 1 (10) ◽

pp. 891-901

Author(s):

R E Malone ◽

R E Esposito

Keyword(s):

Saccharomyces Cerevisiae ◽

Gene Conversion ◽

Genetic Control ◽

Meiotic Recombination ◽

Meiotic Division ◽

Crossing Over ◽

Background Levels ◽

Recombination System ◽

Rad50 Gene ◽

Meiosis I

We have utilized the single equational meiotic division conferred by the spo13-1 mutation of Saccharomyces cerevisiae (S. Klapholtz and R. E. Esposito, Genetics 96:589-611, 1980) as a technique to study the genetic control of meiotic recombination and to analyze the meiotic effects of several radiation-sensitive mutations (rad6-1, rad50-1, and rad52-1) which have been reported to reduce meiotic recombination (Game et al., Genetics 94:51-68, 1980); Prakash et al., Genetics 94:31-50, 1980). The spo13-1 mutation eliminates the meiosis I reductional segregation, but does not significantly affect other meiotic events (including recombination). Because of the unique meiosis it confers, the spo13-1 mutation provides an opportunity to recover viable meiotic products in a Rec- background. In contrast to the single rad50-1 mutant, we found that the double rad50-1 spo13-1 mutant produced viable ascospores after meiosis and sporulation. These spores were nonrecombinant: meiotic crossing-over was reduced at least 150-fold, and no increase in meiotic gene conversion was observed over mitotic background levels. The rad50-1 mutation did not, however, confer a Rec- phenotype in mitosis; rather, it increased both spontaneous crossing-over and gene conversion. The spore inviability conferred by the single rad6-1 and rad52-1 mutations was not eliminated by the presence of the spo13-1 mutation. Thus, only the rad50 gene has been unambiguously identified by analysis of viable meiotic ascospores as a component of the meiotic recombination system.

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ON THE CONTROL OF THE DISTRIBUTION OF MEIOTIC EXCHANGE IN DROSOPHILA MELANOGASTER

Genetics ◽

10.1093/genetics/101.1.81 ◽

1982 ◽

Vol 101 (1) ◽

pp. 81-89

Author(s):

Adelaide T C Carpenter ◽

Bruce S Baker

Keyword(s):

Drosophila Melanogaster ◽

Genetic Control ◽

Low Frequency ◽

Minor Component ◽

Crossing Over ◽

Meiotic Mutants ◽

A Minor

ABSTRACT The effects of eight recombination-defective meiotic mutants on crossing over within the X heterochromatin were examined. Since none permit substantial frequencies of exchange within heterochromatin although six lessen or abolish constraints on the location of exchanges within euchromatin, the systems that prohibit exchange within heterochromatin and that govern where exchanges will occur in euchromatin are under separate genetic control.—A minor component of the effects of mei-218 is the production of nonhomologous exchanges; of mei-9 is the recovery of deleted chromatids; and of mei-41 is the recovery of deleted chromatids and/or a low frequency of heterochromatic exchanges.

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Recombinationless meiosis in Saccharomyces cerevisiae.

Molecular and Cellular Biology ◽

10.1128/mcb.1.10.891 ◽

1981 ◽

Vol 1 (10) ◽

pp. 891-901 ◽

Cited By ~ 66

Author(s):

R E Malone ◽

R E Esposito

Keyword(s):

Saccharomyces Cerevisiae ◽

Gene Conversion ◽

Genetic Control ◽

Meiotic Recombination ◽

Meiotic Division ◽

Crossing Over ◽

Background Levels ◽

Recombination System ◽

Rad50 Gene ◽

Meiosis I

We have utilized the single equational meiotic division conferred by the spo13-1 mutation of Saccharomyces cerevisiae (S. Klapholtz and R. E. Esposito, Genetics 96:589-611, 1980) as a technique to study the genetic control of meiotic recombination and to analyze the meiotic effects of several radiation-sensitive mutations (rad6-1, rad50-1, and rad52-1) which have been reported to reduce meiotic recombination (Game et al., Genetics 94:51-68, 1980); Prakash et al., Genetics 94:31-50, 1980). The spo13-1 mutation eliminates the meiosis I reductional segregation, but does not significantly affect other meiotic events (including recombination). Because of the unique meiosis it confers, the spo13-1 mutation provides an opportunity to recover viable meiotic products in a Rec- background. In contrast to the single rad50-1 mutant, we found that the double rad50-1 spo13-1 mutant produced viable ascospores after meiosis and sporulation. These spores were nonrecombinant: meiotic crossing-over was reduced at least 150-fold, and no increase in meiotic gene conversion was observed over mitotic background levels. The rad50-1 mutation did not, however, confer a Rec- phenotype in mitosis; rather, it increased both spontaneous crossing-over and gene conversion. The spore inviability conferred by the single rad6-1 and rad52-1 mutations was not eliminated by the presence of the spo13-1 mutation. Thus, only the rad50 gene has been unambiguously identified by analysis of viable meiotic ascospores as a component of the meiotic recombination system.

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Male recombination in Brazilian populations of Drosophila ananassae

Genome ◽

10.1139/gen-2015-0169 ◽

2016 ◽

Vol 59 (7) ◽

pp. 493-500 ◽

Cited By ~ 1

Author(s):

Beatriz Goñi ◽

Muneo Matsuda ◽

Yoshiko N. Tobari

Keyword(s):

Genetic Control ◽

Genetic Factors ◽

Regional Distribution ◽

High Variability ◽

Drosophila Ananassae ◽

Crossing Over ◽

Male Recombination ◽

Spontaneous Recombination ◽

Recombination Value ◽

Brazilian Populations

With few exceptions, spontaneous crossing over does not normally occur in male Drosophila. Drosophila ananassae males show considerable amounts of crossing over. In wild males of D. ananassae from Asian (2008) and Brazilian populations (1986 and 2007) variable frequencies of meiotic crossing over, estimated from chiasmata counts, suggested the existence of factors controlling male crossing over in these populations. To corroborate for such prediction, we present data on spontaneous recombination in F1 males of D. ananassae heterozygous for chromosomes of the same Brazilian populations (1986) and marker chromosomes using three testers stocks. Mean recombination value was low, although high variability existed between individual frequencies. Recombination frequencies between lines in each tester stock were not significantly different, excepting when the 3ple-px and 3ple-cy testers were compared (p < 0.05). These two testers differ in respect to the regional distribution of crossovers. The occurrence of recombination in chromosomes 2 and 3 in F1 males tested with e65 se; bri ru was not related, suggesting they are under independent genetic control. Our data are consistent with proposed genetic factors controlling male crossing over in the tester stocks and to the presence of enhancers and suppressors of male crossing over segregating in the Brazilian populations (1986).

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