ABSTRACT

1. Although there is evidence that Cathepsin B (CTSB) regulates the degradation and absorption of yolk precursors during avian ovarian follicle development, nothing is known about its molecular characteristics, tissue distribution or expression profiles in goose ovarian follicular compartments.

2. The intact 1023 bp coding sequence of the goose CTSB gene was obtained for the first time. It encoded a polypeptide of 340 amino acids (AA) containing two conserved functional domains (i.e., Propeptide_C1 and Peptidase_C1A_Cathpsin B) and three active amino acid residues (+108, +279, and +299). Both the nucleotide and AA sequences of goose CTSB gene showed more than 90% similarity with its respective homologs from other avian species.

3. The qRT-PCR results showed that CTSB mRNA was ubiquitously expressed in all examined goose tissues, with moderate to high levels in the reproductive organs including the ovarian stroma and oviduct.

4. Expression of goose CTSB mRNA in the granulosa layers increased gradually from the 2–4 mm F5 follicles but declined to relatively low levels in the F4-F1 follicles while remaining statistically unchanged in the theca layers throughout follicle development.

5. High sequence similarity of goose CTSB gene to other avian species suggested functional conservation of avian CTSB genes, and its fluctuating levels in the granulosa layers may be associated with the orderly progression of goose follicle development. These data laid a foundation for further elucidating the role of CTSB in the avian ovary.

摘要

1.尽管有证据表明组织蛋白酶B（CTSB）调节禽卵子卵泡发育过程中蛋黄前体的降解和吸收，但有关其分子特征，组织分布或在鹅卵泡卵室中的表达分布情况一无所知。

2.首次获得了鹅CTSB基因的完整1023 bp编码序列。它编码了一个包含三个保守功能域（即Propeptide_C1和Peptidase_C1A_Cathpsin B）和三个活性氨基酸残基（+ 108，+ 279和+299）的340个氨基酸（AA）的多肽。鹅CTSB基因的核苷酸序列和AA序列与其其他禽类同系物都显示出超过90％的相似性。

3. qRT-PCR结果显示，CTSB mRNA在所有检查的鹅组织中普遍表达，在包括卵巢基质和输卵管在内的生殖器官中呈中等至高水平表达。

4.鹅CTSB mRNA在颗粒层中从2–4 mm F5卵泡逐渐增加，但在F4-F1卵泡中下降至相对较低的水平，而在整个卵泡发育期间在卵泡膜层中统计上保持不变。

5.鹅CTSB基因与其他禽类的序列高度相似，表明禽CTSB基因具有功能保守性，其颗粒层中的波动水平可能与鹅卵泡发育的有序发展有关。这些数据为进一步阐明CTSB在禽卵巢中的作用奠定了基础。