| The silk gland of silkworm is not only the foundation of silk industry, but also provides us its high effective protein-synthesis function which can be developed to be a new biological industry, so it is honored for its broad applification in research field. A silk gland cell line is essential for us to perform series of reseaches such as the functional investigation of key Fibroin synthesizing genes, the investigation of mechanism about Fibroin synthesizing, and the investigation of silk gland as a biological reactor. However, there is not any cell line whose expression profile is very clear, which has become the bottleneck of those studies. This experiment investigate the genic expression profile of cell line BmSG-SWU1, silk gland specific genes and genes of cell spliting cyclin through whole genome microarray, normal RT-PCR, and fluorescent quantitative PCR (FQ-PCR) analysis, we obtain some results as follows:1. To analysis the expression profile of eighteen genes which are expressed special highly in silk gland, we utilized the whole genome microarray data for silk glands and other tissues of male and female silkworms in day 3 of fifth instar, and the results showed that the expression quantity of 18 genes in silk gland was outclass compared with other tissues. And these eighteen genes contains Hormone-metabolism-related protein, Transporter, Protein-modified degradation phosphorylase, Dehydrogenase and other kinds of proteins, which maybe closely relate to the secretion of Fibroin.2. According to the microarray data for silk glands, we analysed sixteen genes relating to cell cycle controlling, which contained CyclinA, CyclinB, CyclinD, CyclinE, CyclinH, PCNA and Cyclin-dependent kinase cdc2, Cdk2, Cdk5, Cdk6. These genes will be highly expressed mostly in spermary and ovary which have ability to split and multiply in silkworm, but will be lowly expressed in silk gland which has been highly differentiated. The course from female-pupa to moth, is also the exuberant phase of miosis in ovary, meanwhile the expression quantity of these genes gradually largen. So the result shows that these genes correlated with cycle controlling.3. An RT-PCR analyse was performed to analysis eighteen silk-gland-specific genes, and it showed that in the silkgland celline BmSG-SWUl,severeal silk-gland-specific genes were detected, it reveal that BmSG-SWU1 may preserve some characteristics of silk gland cell. Among the eighteen genes, twelve of them were all expressed or none were expressed; six genes showed a different expression profile between tissue and cell, two of them were highly expressed only in silk gland tissue, three of them had higher expression quantity in silk gland and BmSG-SWU1 than those in spermary and ovary, however, they were hardly expressed in BmN-SWU1, and another one was Bmb001492, whose expressions were ubiquitous among the tested tissues.4.The result of FQ-PCR of Fib-L and P25 in different ceils of tissue suggested that, the ceils of BmSG-SWU1 had lost the ability to highly express the Fibroin gene Fib-L and P25. The expression quantity of Fib-L and P25 in silk gland cell line BmSG-SWU1 was only about 0.0013% and 0.0048% respectively compared with that of silk gland; meanwhile that quantity in the ovary cell line BmN-SWU1 was only 0.0016% and 0.0055% respectively. And these suggest that, the expression quantity of these two genes in these two cell lines are nearly consistent, which are far below that of silk gland.5. Then result of RT-PCR about the forecasted silkworm cycle-controlling genes in different tissues and cell lines showed that, the four cyclin genes BmCyclinD2,BmcyclinEI,BmCyclinAl BmCyclinAl had high expression in ovary, silk gland, BmSG-SWU1 and BmN-SWU1, while BmCyclinB and BmCyclinB3 were not expressed in silk gland. Meanwhile, BmPCNA was expressed in these four cDNAs. All the results above suggest that the cell line BmSG-SWU1 has restarted the cycle-controlling genes, and it performs multiplication with mitosis while that of silk gland tissue is endoreduplication.In summary, the cell line of silkworm BmSG-SWU1 passed through long-term cultivated in vitro, they have breakthrough the key point in G2/M from endoreduplication, and returned to a mitostic cycle. Meanwhile, this cell line has lost the ability to highly express the Fibroin gene Fib-L,P25, but has reserved the function of expressing some special genes in former silk gland, and it is a cell line which preserves some characteristics of cells in silk gland.
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