It is a controversial question whether sperm concentrations in humans are changing. Several researchers have reported on environmental factors affecting sperm quality, but the influence of genetic factors is still not fully understood. In this study, we examined the relationship between Y chromosome haplotypes and sperm concentration in fertile males. In addition, we determined the haplotypes of azoospermic patients. The results show that the mean sperm concentration correlates with Y chromosome type. Moreover, the occurrence of azoospermia is related to one particular Y chromosome lineage. Thus, males with a certain haplotype are at a disadvantage for fathering children. The difference of spermatogenic ability among men is important not only in pursuing male competition as in the past but also as relates to the future of modern human males.

A polymorphism in the coding sequence of the SRY gene was found by single-strand conformation polymorphism (SSCP) and direct sequencing analysis. The new allele of the SRY gene, which is raised by a C-to-T transition in the 155th codon, was found in 24% of Honshu, 35% of Okinawan, and 51% of Korean males respectively, whereas it was not observed among 16 Caucasian and 18 Negroid males. A haplotype analysis of the Y chromosome was carried out in Japanese, Korean, Caucasian and Negroid populations, using a combination of the polymorphisms in SRY, DXYS5Y, DYS287, and DXYS241Y loci. The results indicated that the Y chromosomes can be classified into seven haplotypes (Ia, Ib, Ic, IIa, IIb, III, IV). However, of these seven, only four (Ia, IIa, III, IV) were observed in the Japanese population. Furthermore, the presumed haplotype C, Y1, YAP, (CA) 14 , from which haplotype III was probably derived, was not found in any populations in this study. The regional distribution of each haplotype revealed that type III is more frequently observed in Okinawa (16%) and in Korea (21%) than in Honshu (4.4%). The haplotype analysis of the Y chromosome may contribute to the exploration of the origin of Japanese and the relationship between east Asian populations.

Validation of microchip electrophoresis in DNA analysis has been carried out using an Agilent 2100 Bioanalyzer. With a DNA 500 Assay Kit, the reproducibility and accuracy of fragment sizing of a 10 bp DNA ladder have been shown to be satisfactory with the relative standard deviation and the relative error mostly below 1.0 and 5.0% (n = 12), respectively. Both intraday and interday validations of fragment sizing and quantitation have also been performed with a 7500 Assay Kit (n = 48). Although the results of quantitation are not as good as that of sizing, due to the manual introduction of samples and markers into the chip wells, they are still sufficient to carry out further analyses of practical samples. Based on such reliable results, fast analysis of DNA polymorphisms on the human Y-chromosome has been realized with microchip electrophoresis. The total analysis times of three genomic polymorphisms on the Y-chromosome, Y Alu polymorphism, 47z/StuI, and 12f2, are all within 100 s, and the relative standard deviation and relative error of fragment sizes are below 3.5 and 3.7%, respectively. In addition, a mixture of nine DNA markers on the human Y-chromosome related to examine the cause of spermatogenic failure have been separated successfully with the smallest fragment size difference of 7 bp. Our results demonstrate the potential of microchip electrophoresis in polymorphism analysis with the advantages of high speed, good reproducibility, high precision, and high resolution.

Ras oncogenes activated by point mutations do not have a major role in the process of tumorigenesis of chromate-related lung cancer.

Background: Despite being relatively uncommon, testicular germ cell tumors (TGCT) are the most common malignant disease in young men. Epidemiological studies concerning patients with testicular cancer indicate that the most of them have poor semen quality or testicular dysgenesis. However, many studies have shown that the Y chromosome harbors many candidate genes responsible for spermatogenesis process and development and maintenance of the germ cells. The Y chromosome is thought to have a relationship with the formation and progression of TGCT. Materials and methods: To verify this relationship, we investigated if there is any correlation between the Y chromosome structural variations presented as different haplogroups and the occurrence of TGCT in the Japanese population. Using combined haplogroups based on typing of three Y chromosome polymorphic binary markers, we analyzed 68 TGCT derived from Japanese patients together with randomly selected 104 unrelated healthy Japanese matched male controls who were confirmed as residents of the same geographic area. Results: Our findings showed a lack of association between the incidence of TGCT and the different Y-chromosome haplogroups in Japanese population. Conclusion: We concluded that there are no significant variations in males from different Y chromosome lineages regarding their susceptibility or resistance for developing TGCT. The previously hypothesized role of the Y chromosome in the development of TGCT is still uncertain and needs further verification.