Ji Hye Shin

Sexually dimorphic gene expression in the chick brain before gonadal differentiation

Biological bases for sexual differences in the brain exist in a wide range of vertebrate species, including chickens. Recently, the dogma of hormonal dependence for the sexual differentiation of the brain has been challenged. We examined whether sexually dimorphic gene expression in the brain precedes gonadal differentiation. Using the Affymetrix GeneChip Chicken Genome Array, we identified 42 female- and 167 male-enhanced genes that were differentially expressed in sex-specific brains from stage 29 chicken embryos. To confirm the efficacy of the microarray, and to investigate the stage-specific expression patterns of the identified genes, we used quantitative real-time PCR analysis. Our real-time PCR results for the differentially expressed genes agreed well with our microarray results. Thus, we postulate that these genes have potential roles in the sexual differentiation of neural function and development in chickens.

Cloning and functional characterization of chicken interleukin-17D

The chicken interleukin-17D was cloned from a testis cDNA library prepared from the Korean native chicken. The full-length chicken IL-17D (chIL-17D) cDNA consisted of a 348 nucleotide sequence encoding an open reading frame of 116 amino acids with a predicted molecular mass of 13.3kDa. Comparison of the deduced amino acid sequence of chIL-17D with homologous proteins from human, mouse and opossum revealed 64%, 53% and 76% identity, respectively, including six conserved cysteine residues present in the mammalian polypeptides. The chIL-17D gene transcript was expressed in a wide range of tissues, and highest levels were in pancreas, thymus and lung. Following Eimeria maxima infection, levels of the chIL-17D mRNA were up-regulated in the intestinal jejunum, bursa, lung, and spleen but decreased in the thymus. Infected chickens also expressed greater levels of chIL-17D mRNA in CD4(+), CD8(+) and TCR1(+) intestinal intraepithelial lymphocytes while decreased expression was seen in TCR2(+) cells. Treatment of CHCC-OU2 fibroblasts with chIL-17D recombinant protein induced the expression of IL-6 and IL-8. Collectively, these results suggest that chL-17D has structural and functional similarities to mammalian IL-17Ds and that it plays an important role in local gut innate immune responses during experimental coccidiosis.

The reversible developmental unipotency of germ cells in chicken.

We recently developed bimodal germline chimera production approaches by transfer of primordial germ cells (PGCs) or embryonic germ cells (EGCs) into embryos and by transplantation of spermatogonial stem cells (SSCs) or germline stem cells (GSCs) into adult testes. This study was undertaken to investigate the reversible developmental unipotency of chicken germ cells using our established germline chimera production systems. First, we transferred freshly isolated SSCs from adult testis or in vitro cultured GSCs into stage X and stage 14-16 embryos, and we found that these transferred SSCs/GSCs could migrate to the recipient embryonic gonads. Of the 527 embryos that received SSCs or GSCs, 135 yielded hatchlings. Of 17 sexually mature males (35.3%), six were confirmed as germline chimeras through testcross analysis resulting in an average germline transmission efficiency of 1.3%. Second, PGCs/EGCs, germ cells isolated from embryonic gonads were transplanted into adult testes. The EGC transplantation induced germline transmission, whereas the PGC transplantation did not. The germline transmission efficiency was 12.5 fold higher (16.3 vs 1.3%) in EGC transplantation into testis (EGCs to adult testis) than that in SSC/GSC transfer into embryos (testicular germ cells to embryo stage). In conclusion, chicken germ cells from different developmental stages can (de)differentiate into gametes even after the germ cell developmental clock is set back or ahead. Use of germ cell reversible unipotency might improve the efficiency of germ cell-mediated germline transmission.