ABSTRACT. PI3K-Akt-mTOR signaling pathway is associated with endoplasmic reticulum (ER) stress. However, it is not clear how this signaling pathway affects the ER stress. The present study aimed to determine whether the PI3K-Akt-mTOR signaling pathway regulates tunicamycin (TM)-induced increases in mRNA levels of genes involved in the ER stress, to help elucidate the mechanism by which this pathway affects the ER stress in primary goose hepatocytes. Primary hepatocytes were isolated from geese and cultured in vitro. After 12 h in a serumfree medium, the hepatocytes were incubated for 24 h in a medium with either no addition (control) or with supplementation of TM or TM together with PI3K-Akt-mTOR signaling pathway inhibitors (LY294002, rapamycin, NVP-BEZ235). Thereafter, the expression levels of genes involved in the ER stress (BIP, EIF2a, ATF6, and XBP1) were assessed. The results indicated that the mRNA level of BIP 2 Q. Song et al. Genetics and Molecular Research 15 (3): gmr.15037868 was up-regulated in 0.2, 2, and 20 µM TM treatment group (P < 0.05), whereas the mRNA levels of EIF2a, ATF6, and XBP1 were up-regulated in the 2 µM TM treatment group (P < 0.05). However, the TM mediated induction of mRNA levels of genes involved in the ER stress (BIP, EIF2a, ATF6, and XBP1) was down-regulated after the treatment with PI3K-Akt-mTOR pathway inhibitors (LY294002, NVP-BEZ235, and rapamycin). Therefore, our results strongly suggest that the PI3K-AktmTOR signaling pathway might be involved in the down-regulation of the TM-induced ER stress in primary goose hepatocytes.

Histological and developmental study of prehierarchical follicles in geese. Folia Biologica (Kraków) 62: 171-177.The development of the follicular wall and apoptosis of corresponding cells are dependent upon the stage of follicle growth and levels of endogenous hormones. However,the development and apoptosis of prehierarchical follicles in geese is insufficiently known. In order to obtain an understanding about the microstructure, development and apoptosis of prehierarchical follicles in geese, firstly, a histological method was used to investigate the morphological structure of prehierarchical follicles. Results showed that the thickness of granulosa cell layers of the follicular wall increased first, then decreased to the lowest when follicles grew to 9~10 mm in diameter, and the theca layers also thinned to the lowest thickness at the same stage. Moreover, the expression of follicle-stimulating hormone receptor (FSHR) mRNA and the enzyme activity of caspase-3 were analyzed and the results showed that the expression of FSHR was highest when follicles grew to 8~9 mm in diameter (p<0.05); the enzyme activity of caspae-3 was the highest when follicles grew to 6~8 mm in diameter (p<0.05). These collective findings suggested that follicles 6~10 mm in diameter were especially significant, and perhaps represent a turning point from growing follicles to dominant follicles to be selected into a hierarchical sequence or to other follicles to be degenerated during prehierarchical follicle development

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