AN INVESTIGATION OF THE GENETICS OF "MALE SEX-RATIO" PHENOTYPE IN DROSOPHILA PSEUDOOBSCURA

ABSTRACT A laboratory strain of Drosophila pseudoobscura (L116) is studied that, when crossed to sex-ratio homozygous females, produces sons that exhibit varying levels of the male sex-ratio (msr) phenotype. The msr phenotype occurs only in sex-ratio males and is due to the production of a high frequency of nullo-XY sperm. The level of the msr phenotype is variable, and new variability is generated in one father-son transmission. Pedigree studies indicate the genes for msr reside on the Y chromosome or the autosomes of the L116 stock.

Download Full-text

Modifier Genes of the Sex Ratio Trait in Drosophila pseudoobscura

Genetics ◽

10.1093/genetics/116.2.275 ◽

1987 ◽

Vol 116 (2) ◽

pp. 275-283

Author(s):

Gary Cobbs

Keyword(s):

Sex Ratio ◽

Y Chromosome ◽

X Chromosome ◽

High Frequency ◽

Sex Chromosome ◽

Drosophila Pseudoobscura ◽

Sterile Male ◽

Very High Frequency ◽

Very High ◽

Chromosome Nondisjunction

ABSTRACT The msr trait of Drosophila pseudoobscura occurs when "sex-ratio" males produce a very high frequency of null-X sperm which give rise to sterile male (X/O) progeny. The trait involves dramatically lowered fecundity due to spermiogenic failure. The msr trait is multigenic and the genes are located on autosomes II, III and IV of the L116 laboratory stock. This stock also carries genes on the Y chromosome that lower the level of msr. When the genes on the L116 autosomes are present together or with those on the Y chromosome of other stocks, they interact cooperatively to produce very high levels of msr. The msr genes require the presence of a sex-ratio X chromosome to have any effect and thus may be regarded as modifiers of the "sex-ratio" phenotype. Crosses show that the genes causing msr are primarily recessive but have some expression when heterozygous. Sex chromosome nondisjunction is proposed as the mechanism underlying the msr trait.

Download Full-text

An Effect of the Y-Chromosome on the Sex-Ratio of Interracial Hybrids of Drosophila Pseudoobscura

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.23.7.360 ◽

1937 ◽

Vol 23 (7) ◽

pp. 360-362 ◽

Cited By ~ 4

Author(s):

A. H. Sturtevant

Keyword(s):

Sex Ratio ◽

Y Chromosome ◽

Drosophila Pseudoobscura

Download Full-text

PRELIMINARY CHARACTERIZATION OF "SEX RATIO" AND REDISCOVERY AND REINTERPRETATION OF "MALE SEX RATIO" IN DROSOPHILA AFFINIS

Genetics ◽

10.1093/genetics/71.4.597 ◽

1972 ◽

Vol 71 (4) ◽

pp. 597-606

Author(s):

Robert A Voelker

Keyword(s):

Sex Ratio ◽

Y Chromosome ◽

X Chromosome ◽

Sex Ratios ◽

Meiotic Drive ◽

General Consideration ◽

Female Progeny ◽

Chromosome Sequence ◽

Male Sex

ABSTRACT In D. affinis "sex ratio" (sr), a form of meiotic drive characterized by the production of mostly or only female progeny by certain males, is associated with two different X chromosome sequences, XS-I XL-II and XS-II XL-IV. The behavior of the two sequences differed, depending on the Y chromosome constitution, being either Y L or 0. Males with sequence XS-II XL-IV and Y L produced progenies with nearly normal sex ratios; males with the same X chromosome sequence but in the absence of a Y chromosome in some cases gave progenies with nearly normal sex ratios but in other cases gave progenies which tended toward phenotypic sr. Males with sequence XS-I XL-II and Y L gave progenies which were characteristically sr (0.97–0.98 females); in the absence of a Y chromosome males with this sequence produced progenies which were virtually all-male. This latter finding is presumably identical to Novitski's (1947) "male sex ratio" (msr). The interpretation offered here attributes msr to an interaction between sr sequence XS-I XL-II and the 0 condition. A general consideration of the available data on sr in D. affinis is presented.

Download Full-text

The influence of the male sex gland on the female. An experimental study to determine the sex ratio of the offspring

American Journal of Obstetrics and Gynecology ◽

10.1016/s0002-9378(25)90594-7 ◽

1925 ◽

Vol 10 (4) ◽

pp. 527-544 ◽

Cited By ~ 5

Author(s):

Francis Kovacs

Keyword(s):

Experimental Study ◽

Sex Ratio ◽

Male Sex

Download Full-text

Multiple Mating and the "Sex-Ratio" Trait in Drosophila pseudoobscura

Evolution ◽

10.2307/2407837 ◽

1981 ◽

Vol 35 (2) ◽

pp. 275 ◽

Cited By ~ 12

Author(s):

Andrew Beckenbach

Keyword(s):

Sex Ratio ◽

Multiple Mating ◽

Drosophila Pseudoobscura

Download Full-text

Common Spontaneous Sex-Reversed XX males of the Medaka Oryzias latipes

Genetics ◽

10.1093/genetics/163.1.245 ◽

2003 ◽

Vol 163 (1) ◽

pp. 245-251 ◽

Cited By ~ 1

Author(s):

Indrajit Nanda ◽

Ute Hornung ◽

Mariko Kondo ◽

Michael Schmid ◽

Manfred Schartl

Keyword(s):

Y Chromosome ◽

Oryzias Latipes ◽

Fish Analysis ◽

Normal Phenotype ◽

Dmrt1 Gene ◽

Male Development ◽

Female Bias ◽

Male Sex ◽

Xx Males ◽

Number Of Males

Abstract In the medaka, a duplicated version of the dmrt1 gene, dmrt1bY, has been identified as a candidate for the master male sex-determining gene on the Y chromosome. By screening several strains of Northern and Southern medaka we identified a considerable number of males with normal phenotype and uncompromised fertility, but lacking dmrt1bY. The frequency of such males was >10% in some strains and zero in others. Analysis for the presence of other Y-linked markers by FISH analysis, PCR, and phenotype indicated that their genotype is XX. Crossing such males with XX females led to a strong female bias in the offspring and also to a reappearance of XX males in the following generations. This indicated that the candidate male sex-determining gene dmrt1bY may not be necessary for male development in every case, but that its function can be taken over by so far unidentified autosomal modifiers.

Download Full-text

Analysis of the sex ratio in Bradysia matogrossensis (Diptera, Sciaridae)

Genetics and Molecular Biology ◽

10.1590/s1415-47572000000100018 ◽

2000 ◽

Vol 23 (1) ◽

pp. 97-103 ◽

Cited By ~ 4

Author(s):

Lincoln S. Rocha ◽

André Luiz P. Perondini

Keyword(s):

Sex Ratio ◽

Sex Determination ◽

X Chromosome ◽

Control Mechanism ◽

Sex Ratios ◽

Laboratory Strain ◽

Chromosome Elimination ◽

Common Control ◽

Males And Females ◽

Successive Generations

In sciarid flies, the control of sex determination and of the progeny sex ratio is exercised by the parental females, and is based on differential X-chromosome elimination in the initial stages of embryogenesis. In some species, the females produce unisexual progenies (monogenic females) while in others, the progenies consist of males and females (digenic females). The sex ratio of bisexual progenies is variable, and departs considerably from 1:1. Bradysia matogrossensis shows both monogenic and digenic reproduction. In a recently established laboratory strain of this species, 15% of the females were digenic, 10% produced only females, 13% produced only males, and 62% produced progenies with one predominant sex (33% predominantly of female and 29% predominantly male progenies). These progeny sex ratios were maintained in successive generations. Females from female-skewed progenies yielded female- and male-producing daughters in a 1:1 ratio. In contrast, daughters of females from male-skewed progenies produce bisexual or male-skewed progenies. The X-chromosome of B. matogrossensis shows no inversion or other gross aberration. These results suggest that the control of the progeny sex ratio (or differential X-chromosome elimination) involves more than one locus or, at least, more than one pair of alleles. The data also suggest that, in sciarid flies, monogeny and digeny may share a common control mechanism.

Download Full-text

The detection of female cell activity in male sex chromosome chimeric Rideau Arcott sheep, using the Xist gene product as a marker

SURG Journal ◽

10.21083/surg.v1i2.414 ◽

2008 ◽

Vol 1 (2) ◽

pp. 20-25

Author(s):

Okimi Peters ◽

W. Allan King

Keyword(s):

Y Chromosome ◽

Sex Chromosome ◽

Cell Activity ◽

Xist Gene ◽

Specific Gene ◽

Xist Expression ◽

Female Cell ◽

Male Sex ◽

Polymerase Chain ◽

Xy Female

The detection of the SRY (Sex-determining region on the Y chromosome) gene is a popular method used for the identification of freemartins (XX/XY female chimeras). This method relies on the fact that the SRY gene is a Y chromosome specific gene and is thus normally only present in males therefore detecting its presence in a female indicates the presence of male cells (XY cells) within the female. This concept can be extrapolated to the male counterparts of freemartins with regards to the Xist gene. This gene is normally only widely expressed in females and can be used as a marker for identifying females. Therefore, detecting Xist gene expression in males (in tissues other than the testes, as the Xist gene is expressed exclusively in the testes of males) may indicate that these males contain transcriptionally competent female cells and thus necessarily labels them as sex-chromosome chimeras. In the present study four previously identified male sex chromosome chimeras were screened for the expression of the Xist gene using reverse transcription Polymerase Chain Reaction (PCR), and it was detected in three of the four chimeras. Xist expression was not detected in one of the chimeras because the proportion of female cells in its blood is significantly low and thus it is likely that the blood sample used in the study did not possess female cells. None-the-less it was concluded that the detection of Xist expression in male sex chromosome chimeras can be used as an indication of the presence and transcriptional competence of female cells within them.

Download Full-text