Studies On The Roles Of Gonadal Peptide Hormones As Local Regulators Of Follicular Development In Poultry

This research is focused on: 1) cDNA cloning and sequence analysis of the mature inhibin/activin α. βA,β B subunit from Xianju chicken; 2) mRNA expression of Inhibin/Activin and related hormones, factor and receptor (follistatin, FSH receptor, Wilms" tumor suppressor) using a sensitive quantitative competitive reverse transcription-polymerase chain reaction (QC RT-PCR). The main results and conclusions are as following:The mature a -subunit of Xiaoshan chicken / Shao duck is a fragment of 113/113 amino acids containing one glycosylation site and seven cysteine residues. It is approximately 97-99% / 91.25-9231% and 58.46-61.73% / 60.86-63.41% identical in nucleotide sequence, 96.46-99.12% / 93.97-95.23% and 57 78-61.94% / 55.81-60.93% similar in deduced amino acid sequence, respectively, in the mature region to the chicken and mammalian inhibin α -subunit cDNA clone.The mature βA-subunit of Xiaoshan chicken / Shao Duck is a fragment of 116 /116 amino acids containing nine cysteine residues. It is 99.72-100% / 95.44-95.73% and 83.48-86.04% / 84.62-87.75% similar in nucleotide sequence, 99.14-100% / 99.14-100% and 94 83-97.41% / 95.69-98.28% identical in deduced amino acid sequence, respectively, in the mature region to the reported chicken and mammalian inhibin/activin βA-subunit cDNA sequences.The mature βB-subunit of Xiaoshan chicken / Shao duck is a fragment of 115 /115 aminc acids containing nine cysteine residues. It is 100% / 99.43% and 80.75-83.62% / 8075-83.91% identical in nucleotide sequence, 100% / 100% and 95.69-98.28% 95.69-98.28% similar in deduced amino acid sequence, respectively, in the mature region to the reported chicken and mammalian inhibin/activin βB-subunit cDNA clone.As for the mature chicken inhibin a -subunit, the number of potential glycosylation site (one) and cysteine residues (seven) was same, and their corresponding positions in the amino acid sequences were almost identical as compared to chicken and mammalian inhibin a -subunit, And for βA and βB-subunit, the number of cysteine residues (nine) is same, and their positions in the amino acid sequences are almost identical as compared to thecorresponding sequences of A and B subunit reported in GenBank; which indicates that the inhibin/activin subunits are highly conserved among different species, implying important roles of inhibin/activin subunits in various animalsThe mRNA expression pattern of inhibin a subunit in the developing ovarian follicles of Xianju chicken was investigated. The result revealed that the expression of inhibin a subunit is highest in small yellow follicles (SYF), and the expression of a -subunit decreased with further follicle maturity from SYF to F1 follicle. The higher level of inhibin a -subunit mRNA was found in the large and SYF follicles, and the lowest level was found in LWF, which indicated that inhibin subunit played an important role during the course of follicular recruitment, selection and dominance.The expression of mRNA for the inhibin a and inhibin/activin A subunit in the developing ovarian follicles of the duck was also detected. The results indicated all follicles showed the expression of mRNA for the inhibin a and inhibin/activin A. The inhibin a subunit mRNA was expressed more abundantly than the A subunit in the large preovulatory follicles Competitive RT-PCR revealed that the expression of inhibin a subunit was highest in small yellow follicles (SYF). The highest level of inhibin/activin mRNA was found in the F1. follicle The expression of the a subunit was reduced with follicular development whereas A subunit expression was dramatically enhanced, which indicated the expression of inhibin a and inhibin/activin A subunit was differentially regulated during follicular development. In addition, the highest level of A mRNA in F1 follicle indicated the production of dimeric inhibin and/or activin primarily occurred in the largest F1 follicle.Folllistatin and inhibin/activin were closely related glycoprotein hormones. The expression of...