Effects of 17beta-estradiol on distribution of primordial germ cell migration in male chicks.

AIM: To assess whether exogenous estradiol has any effect on migration of primordial germ cells (PGCs) in the chick. METHODS: Fertilized eggs were treated with 17beta-estradiol (E(2)) (80 microg/egg) at stage X (day 0 of incubation), stages 8-10 (incubation 30 h) and 13-15 (incubation 55 h). Controls received vehicle (emulsion) only. Changes in PGC number were measured on different days according to developmental stages. RESULTS: In male right gonads, but not in female left gonads, at stages 28-30 (incubation 132 h) significant decreases in the mean number of PGCs aggregating were observed compared with the controls (P < 0.05) while the total PGC number in the right and left gonads at each stage did not change (P > 0.05). CONCLUSION: The present study provides evidence that E(2) has significant effects on the localization of PGCs in male right, but not female left, gonads of chicken embryos at stages 28-30, compared with controls.

Cloning and characterization of chicken SPATA4 gene and analysis of its specific expression.

The spermatogenesis associated 4 gene (SPATA4, previously named TSARG2) was first cloned from a mouse testis cDNA library and was reported to be a candidate apoptosis-related gene in male germ cells. In this study, we cloned and characterized the SPATA4 gene from chicken (Gallus gallus). Bioinformatics analysis shows that the chicken SPATA4 gene is located on chromosome 4, is made up of six exons, and contains an 860 bp open reading frame encoding a putative protein of 250 amino acids. Further analysis of the SPATA4 gene sequence indicates that it is highly conserved between avian and mammalian species. Multi-tissue RT-PCR results indicate that the chicken SPATA4 gene is specifically expressed in the testis. Moreover, according to multi-time RT-PCR results, the expression of chicken SPATA4 occurs in a development stage-dependent pattern, and is gradually upregulated during the developmental process in chicken testis. All of these results suggest that SPATA4 may play an important role in the chicken spermatogenesis process.

Blastocysts produced by nuclear transfer between chicken blastodermal cells and rabbit oocytes.

Interspecies nuclear transfer (INT) has been used as an invaluable tool for studying nucleus-cytoplasm interactions; and it may also be a method for rescuing endangered species whose oocytes are difficult to obtain. In the present study, we investigated interaction of the chicken genome with the rabbit oocyte cytoplasm. When chicken blastodermal cells were transferred into the perivitelline space of rabbit oocytes, 79.3% of the couplets were fused and 9.7% of the fused embryos developed to the blastocyst stage. Both M199 and SOF medium were used for culturing chicken-rabbit cloned embryos; embryo development was arrested at the 8-cell stage obtained in SOF medium, while the rates of morulae and blastocysts were 12.1 and 9.7%, respectively, in M199 medium. Polymerase chain reaction (PCR) amplification of nuclear DNA and karyotype analyses confirmed that genetic material of morulae and blastocysts was derived from the chicken donor cells. Analysis mitochondrial constitution of the chicken-rabbit cloned embryos found that mitochondria, from both donor cells and enucleated oocytes, co-existed. Our results suggest that: (1) chicken genome can coordinate with rabbit oocyte cytoplasm in early embryo development; (2) there may be an 8- to 16-cell stage block for the chicken-rabbit cloned embryos when cultured in vitro; (3) mitochondrial DNA from the chicken donor cells was not eliminated until the blastocyst stage in the chicken-rabbit cloned embryos; (4) factors existing in ooplasm for somatic nucleus reprogramming may be highly conservative.