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

Genetics ◽  
2003 ◽  
Vol 163 (1) ◽  
pp. 245-251 ◽  
Author(s):  
Indrajit Nanda ◽  
Ute Hornung ◽  
Mariko Kondo ◽  
Michael Schmid ◽  
Manfred Schartl

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.

1970 ◽  
Vol 2 (S2) ◽  
pp. 7-30 ◽  
Author(s):  
C. E. Ford

SummarySex in man and probably throughout the class mammalia is normally determined by the presence of a Y chromosome (male) or its absence (female). The presence of genetic loci on both the long and the short arm of the X chromosome in double dose appears to be essential for the development of mature functional ovaries in the human female though a single X suffices in the female mouse.The development of masculine genital anatomy and phenotype is a consequence of prior formation of testes. In the absence of gonads of either kind, female internal and external genitalia are formed but secondary sex development fails. In rare human families a mutant gene suppresses the development of male external genitalia in 46, XY embryos but permits the development of testes and male internal genitalia. The external phenotype is normal female (syndrome of testicular feminization). A sex-linked mutant gene in the mouse has a similar effect.The locus or loci directly concerned with male development might lie wholly on the Y chromosome or might be located on another chromosome or chromosomes. In the latter case it (or they) must be repressed in the female and normally activated by a locus or loci on the Y chromosome in the male. Present evidence does not permit the exclusion of either possibility.


SURG Journal ◽  
2008 ◽  
Vol 1 (2) ◽  
pp. 20-25
Author(s):  
Okimi Peters ◽  
W. Allan King

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.


2005 ◽  
Vol 53 (3) ◽  
pp. 319-322 ◽  
Author(s):  
Susanne Mergenthaler ◽  
Tatiana Babochkina ◽  
Vivian Kiefer ◽  
Olaf Lapaire ◽  
Wolfgang Holzgreve ◽  
...  

Current cytogenetic approaches in noninvasive prenatal diagnosis focus on fetal nucleated red blood cells in maternal blood. This practice may be too restrictive because a vast proportion of other fetal cells is ignored. Recent studies have indicated that fetal cells can be directly detected, without prior enrichment, in maternal blood samples by fluorescence in situ hybridization (FISH) analysis for chromosomes X and Y (XY-FISH). In our blinded analysis of 40 maternal blood samples, we therefore examined all fetal cells without any enrichment. Initial examinations using conventional XY-FISH indicated a low specificity of 69.4%, which could be improved to 89.5% by the use of two different Y-chromosome-specific probes (YY-FISH) with only a slight concomitant decrease in sensitivity (52.4% vs 42.9%). On average, 12–20 male fetal cells/ml of maternal blood were identified by XY- and YY-FISH, respectively.


2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Oki Hayasaka ◽  
Yutaka Takeuchi ◽  
Kazuhiro Shiozaki ◽  
Kazuhiko Anraku ◽  
Tomonari Kotani

Andrologia ◽  
2012 ◽  
Vol 45 (2) ◽  
pp. 140-144 ◽  
Author(s):  
L.-C. Kuan ◽  
M.-T. Su ◽  
P.-L. Kuo ◽  
T.-C. Kuo

2008 ◽  
Vol 68 (5) ◽  
pp. 791-799 ◽  
Author(s):  
Yoshiyuki Kojima ◽  
Yutaro Hayashi ◽  
Kentaro Mizuno ◽  
Shoichi Sasaki ◽  
Yuko Fukui ◽  
...  
Keyword(s):  

2002 ◽  
Vol 99 (18) ◽  
pp. 11778-11783 ◽  
Author(s):  
I. Nanda ◽  
M. Kondo ◽  
U. Hornung ◽  
S. Asakawa ◽  
C. Winkler ◽  
...  
Keyword(s):  

1956 ◽  
Vol 34 (2) ◽  
pp. 261-268 ◽  
Author(s):  
Áskell Löve ◽  
Nina Sarkar

The western North American dioecious species Rumex paucifolius is shown to be a tetraploid with 2n = 28 chromosomes. It is the third tetraploid known within the subgenus Acetosa, and the first polyploid dioecious taxon of that group, the others having either 2n = 14 ♂, 15 ♀ (R. Acetosa and relatives), or 2n = 8 ♂, 9 ♀ (R. hastatulus). The sex chromosomes of R. paucifolius are of the XX:XY type, the male sex being heterogametic. The X is a large chromosome, while the Y is the smallest chromosome of the complement. The mechanism of sex determination of R. paucifolius follows the Melandrium–Acetosella scheme with strongly epistatic male determinants in the Y–chromosome. Other dioecious Acetosae follow the Drosophila–Acetosa scheme of sex determination with a balance between the number of X and autosome complements, the Y being sexually inert. It is concluded from the observed cytogenetical and morphological differences that R. paucifolius should constitute a section of its own, Paucifoliae, which should be placed as far as possible from the section Acetosa, though within the same subgenus. The other American dioecious endemic, R. hastatulus, is placed in a subsection of the section Acetosa.


1999 ◽  
Vol 112 (1) ◽  
pp. 21-25 ◽  
Author(s):  
Willem E de Graaff ◽  
Jannie van Echten ◽  
Anneke Y van der Veen ◽  
Dirk Th Sleijfer ◽  
Albertus Timmer ◽  
...  

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