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At least 19 recordsLinked to original sources

What do the X and Y chromosomes tell us about sex and gender in forensic case analysis?

Sex determination can be particularly crucial in forensic casework such as rape cases or cases of missing persons. Biological traces have to be genetically typed and the classification of the sex is of great importance for further investigations. Lately, several papers were published on reliability of sex determination by genetic typing of amelogenin gene-specific fragments. Problems may arise not only from false detection (or non-detection) of amelogenin-specific fragments, but also in cases of chimerism (bone marrow transplants) or micro chimerism (pregnant women carrying male fetuses), and from the possible discrepancies between the biological gender and the (forensic relevant) legal gender in the personal identity documents. The phenotype based classification of the legal gender may contradict the genetic sex under several conditions as there are genetic diversity, intersex conditions and transsexualism. The forensic relevance of the possible misinterpretation (sex is not necessarily legal gender) should not be underestimated.

Amelogenin↗

Molecular analysis of sex determination in sex-reversed and true hermaphroditism.

The SRY (sex region of Y) gene determines testis formation but not all cases of sex reversal in humans can be explained by alterations in this gene. We studied one 46,XY female, four 46,XX males, and nine true hermaphrodites (TH): three with an XY and six with an XX chromosomal constitution. The SRY gene was identified in the XX males and the TH with a Y chromosome but was not demonstrated in the XY female and the six XX TH. The Y-heterochromatin region was also identified in one 46,XX male, indicating a low grade mosaicism undetected by cytogenetics. The amplification of the amelogenin gene showed the presence of a 977-bp band that belongs to the short arm of chromosome X in all patients but the absence of a 780-bp band of the short arm of chromosome Y in three 46,XX males and in all the 46,XX TH. These studies demonstrate that the molecular study of sex-reversed patients and TH will help to understand the complex mechanisms of sex determination. The SRY gene is involved but other genes on the X chromosome and autosomes still remain to be studied.

Adolescent↗

Identification of a sex-determining region in Nile tilapia (Oreochromis niloticus) using bulked segregant analysis.

Sex determination in the Nile tilapia (Oreochromis niloticus) is thought to be an XX-XY (male heterogametic) system controlled by a major gene. We searched for DNA markers linked to this major locus using bulked segregant analysis. Ten microsatellite markers belonging to linkage group 8 were found to be linked to phenotypic sex. The putative Y-chromosome alleles correctly predict the sex of 95% of male and female individuals in two families. Our results suggest a major sex-determining locus within a few centimorgans of markers UNH995 and UNH104. A third family from the same population showed no evidence for linkage of this region with phenotypic sex, indicating that additional genetic and/or environmental factors regulate sex determination in some families. These markers have immediate utility for studying the strength of different Y chromosome alleles, and for identifying broodstock carrying one or more copies of the Y haplotype.

Animals↗

Rapid detection of male-specific DNA sequence in bovine embryos using fluorescence in situ hybridization.

An accurate, reliable, and quick (less than an hour) method for determining the sex of bovine embryos was developed using a fluorescence in situ hybridization (FISH), with a probe designed from a bovine Y chromosome specific DNA (BC1.2). First, to improve a protocol of FISH and evaluate an accuracy of the method, lymphocyte nuclei prepared from three bulls, two cows, and one freemartin were tested. We found that 5 min was enough for hybridization. The washing solution adequate for posthybridization was 0.5x SSC at 72 degrees C for 5 min. The whole procedure for FISH can be accomplished in less than an hour. A male-specific signal was detected, on average, as 97, 0.5, and 83%, respectively, of lymphocytes in males, females, and a freemartin. Using the rapid FISH protocol developed, 28 embryos were divided. According to the presence of the digoxigenin signal, 16 embryos (57.1%) were predicted as male, and 12 embryos (42.9%), predicted as female.

Animals↗

[Discriminant analysis of the mandible for sex determination].

Seventeen measuring parameters were used to characterize 197 mandibles (109 males, 88 females) taken from the corpses of people 20-80 years of age from the Rhine-Main-Neckar area. The representative measuring parameters and discriminating functions of intact lower jaws and lower jaw fragments of most frequent fracture types were determined in this practice group by means of discriminating analysis. In the present research material it was possible to determine sex accurately from an intact lower jaw bone in 82.6% (m) and 79.5% (f) of the cases. Furthermore, our results show clearly that sex may even be determined from lower jaw fragments. The classification was correct, depending on the type of fragment, in 72.5%-81.7% (m) and 71.6%-79.5% (f) of the cases.

Adult↗

[Biotinylated Y chromosome specific probe for human sexing].

Human chromosome DNA from WBC or fetus chorion samples were digested with Hae III and hybridized with biotinylated Y chromosome specific probe by Southern blotting, and hybridization signals were developed by the ABC (Avidin-biotin-alkaline phosphatase complex) system. The hybridization signal for 0.1 microgram of male DNA could be detected clearly, while the signal for even 5 micrograms of female DNA could not. Parallel tests showed that the sexing results using 32P-labeled and biotinylated Y probe were identical. This suggests that the biotinylated Y probe can be applied to the determination of X-linked genetic diseases and sex abnormality, forensic analysis, sex determination of sportsmen and women, heterosexual transplantation of bone marrow, etc. It could become a convenient means for genetic diagnosis.

Affinity Labels↗

Change of the heterogametic sex from male to female in the frog.

Two different types of sex chromosomes, XX/XY and ZZ/ZW, exist in the Japanese frog Rana rugosa. They are separated in two local forms that share a common origin in hybridization between the other two forms (West Japan and Kanto) with male heterogametic sex determination and homomorphic sex chromosomes. In this study, to find out how the different types of sex chromosomes differentiated, particularly the evolutionary reason for the heterogametic sex change from male to female, we performed artificial crossings between the West Japan and Kanto forms and mitochondrial 12S rRNA gene sequence analysis. The crossing results showed male bias using mother frogs with West Japan cytoplasm and female bias using those with Kanto cytoplasm. The mitochondrial genes of ZZ/ZW and XX/XY forms, respectively, were similar in sequence to those of the West Japan and Kanto forms. These results suggest that in the primary ZZ/ZW form, the West Japan strain was maternal and thus male bias was caused by the introgression of the Kanto strain while in the primary XX/XY form and vice versa. We therefore hypothesize that sex ratio bias according to the maternal origin of the hybrid population was a trigger for the sex chromosome differentiation and the change of heterogametic sex.

Animals↗

Non-invasive early prenatal diagnosis using fluorescent in situ hybridization on transcervical cells: comparison of two different methods for retrieval.

OBJECTIVE: We compared the efficiencies of uterine and endocervical lavage to retrieve fetal cells from first trimester pregnancies for further analysis with fluorescent in situ hybridization (FISH). STUDY DESIGN: Transcervical cell (TCC) samples were collected at 7-10 weeks of gestations by uterine lavage (13 women) and by endocervical lavage (12 women) who were scheduled for volunteer termination of pregnancy. A sample of placenta was also obtained for cytogenetic analysis to confirm the sex or genotype in the end of the procedure. FISH was performed using probes for the chromosomes 18, X and Y in a three color hybridization protocol. The statistical analysis included chi(2)-analysis, and t-test. RESULTS: Sufficient cells were obtained in 12 of the 13 (92.3%) in uterine lavage and 10 of the 12 (83.3%) in endocervical lavage group for FISH procedures for fetal sex prediction. The mean success rate of signal detection for FISH procedure was 91.7% (range 83-97%). Fetal sex was correctly predicted in 11 of 12 (91.6%) with uterine lavage and 8 of 10 (80.0%) in endocervical lavage and the difference was statistically insignificant. CONCLUSION: This study demonstrated that there are available cells of fetal origin in the lower part of the uterus and these cells may be collected successfully as early as 7 weeks of the gestation. In addition, our results show that endocervical lavage method is as effective as uterine lavage. FISH has been successfully used to detect status of aneuploidy and sex of the fetus from TCC.

Cervix Uteri↗

Hormonal induction of supermale golden rosy barb and isolation of Y-chromosome specific markers.

Viable supermales of the golden rosy barb Puntius conchonius are generated through hormonal sex reversal and progeny testing. Discrete immersion (3 h/day on the second, fourth, and sixth day after hatching) of the fry in Estradiol-17beta (E2) at doses of 400-600 microg/L ensures greater than 40% survival and production of more than 98% F1 females; of these 50% are heterogametic females, that when crossed with normal males, sire 25% YY supermales. Supermales sire female progenies at the frequencies between 0 and 8%. Reproductive performance of hormonally sex-reversed females and androgenetic females is inferior to the normal ones. Conversely, the performance of androgenetic males is superior but suffers from low fertilizability. The relative performance of supermale produced by breeding sex-reversed parents is superior to those produced by androgenesis. Using the SRY-specific primers, the PCR analysis of the genomic DNA of the male golden rosy barb produces three products of 588, 333, and 200 bp length. However only the 200 bp product is amplified in the female genome. Hence it is possible to use the first two products as molecular markers to rapidly identify fish possessing a Y chromosome. The presence of 333 and 588 bp fragments in normal (X1Y2), hormonally induced (Y1Y2) and androgenetic (Y2Y2) males and the absence of relation between the 200 bp fragment and the X-chromosome indicates that the male specific markers are specific to Y-chromosome. For the first time, a Y-chromosome specific molecular marker for a cyprinid has been identified, isolated, and characterized.

Animals↗

Sonographic biometrical range of external genitalia differentiation in the first trimester of pregnancy: analysis of 2593 cases.

OBJECTIVES: The aim of this study was to establish the accuracy of fetal gender assignment by sonography in the biometrical range of 18 to 29 mm of biparietal diameter (BPD). METHODS: Transvaginal and/or transabdominal sonography was used to detect the sagittal sign as a marker of fetal gender in 2593 fetuses with BPD between 18 and 29 mm. The results of sonographic examination were compared with the gender at birth or with karyotype obtained from amniotic fluid cells or chorionic villus sampling. RESULTS: Fetal gender assignment was feasible in 2374 of 2593 cases (91%). Of the 2188 fetuses with known fetal sex outcome, 1025 were males and 1157 were females, and 6 had genital anomalies. In fetuses without genital anomalies, an accuracy rate of 100% was achieved at a BPD of >/=24 mm. The results of the six cases with genital malformations were considered separately. CONCLUSION: Sonography is a reliable method for the study of the morphological development of the external genitalia in fetuses 'in vivo'; it is possible to assign fetal gender in 95 to 99% starting at a BPD of 20 mm and to achieve an accuracy rate of 99 to 100% from a BPD of 22 mm, but fetal sex assignment should not be undertaken below a BPD of 22 mm, and especially not in cases where fetal sexing affects pregnancy management.

Amniotic Fluid↗

Follicular fluid steroid levels and subsequent sex of bovine embryos.

On the basis of evidence suggesting a maternal involvement in the determination of the sex of the offspring, we took ova at the point of ovulation from crossbred heifers, fertilised them, and established the sex of the embryos. At the same time we took individual-matched samples of follicular fluid from each follicle of origin, and measured the levels of testosterone and oestradiol, blind to the sex of the embryo. We found no effect of oestradiol on sex in either primary or subordinate follicles. But bovine ova from subordinate follicles that had follicular fluid with a high concentration of testosterone (in vivo) were later more likely to be fertilised by a Y-chromosome-bearing spermatozoon (in vitro). These, along with similar results from other researchers, suggest that further study of the relationship between mammalian follicular hormones at the time of conception and subsequent sex of offspring, may help resolve some of the problems associated with theories of adaptive control of the sex ratio in mammals.

Animals↗