| BEVS is one of the most popular expressive systems in the gene engineeringfield, and BmNPV-Bm system which belongs to BEVS has a far future especially inChina. When put it into the reality, there are some obstacles to be solved: firstly,aseptic technique based on artificial diet is absolutely necessary while BmNPVsystem is used to produce bacterin or other proteinic medications; secondly, theinoculability way at present couldn't meet the need of large scale production for itslow efficiency because the recombination NPV has a poor ability of peroral infection;thirdly, there's much work to do in increasing the expressive amount of foreign genein BmNPV system. There are many tricks to solve problems above, among of which, maybe abetter one, is focusing on the host of parasite of BmNPV——the silkworm.Accordingly, aiming at the practicability of silkworm bioreactor, this paper screenedout several silkworm varieties for BmNPV-Bm system, particularly in the threeaspects of artificial diet adaptability, peroral incidence rate of recombination NPVand, expressive amount of foreign gene. The main results are as follows: 1. Integrated adaptability for artificial diet was investigated among 53 silkwormvarieties, and the result showed that there were remarkable differences betweendifferent silkworm varieties. It was revealed that the varieties chun╳yue(973╳974)and zaA╳mingzhu had the best performance in integrated adaptability. Chun╳yuewas a new variety reproduced by our research branch, and displayed its excellentfeeding habit for artificial diet, high cocoon production and many other goodcharacteristics. ZaA, as a polyphagous variety, was a perfect fundamental materialfor artificial diet. In addition, jingsong╳haoyue and 9405╳9406 used in practicewere both outstanding varieties for artificial diet rearing. 2. There were notable differences between different silkworm varieties forartificial diet with fluorescer VBL, a kind of synergia stuff used to enhance the rateof incidence. The varieties zaA, jingsong╳haoyue, 9405╳9406, yue╳chun, allshowed active ingestion of the diet with VBL. 3. Different silkworm varieties had marked distinctions in the rate of peroralincidence. ZaA, jingsong╳haoyue, 9405╳9406 and yue╳chun did well in the VIIIexperiment. 4. There were prominent differences between different silkworm varieties onexpressive activity for foreign genes bearing recombination NPV. Five varieties,named zaA, 9405╳9406, jingsong╳haoyue, yue╳chun and 161.162╳136.137,obtained highest expressive amount among the varieties in the test. 5. It was made sure that zaA, chun╳yue(yue╳chun), zaA╳mingzhu, 9405╳9406and jingsong╳haoyue were all destination varieties for BmNPV-Bm system afterrepetitious filtration, which based upon 5 indexes such as the adaptability forartificial diet for 1-2 instars, the adaptability for artificial diet for all instars, theingestion of the diet with fluorescer VBL, the peroral incidence rate ofrecombination NPV and the expressive amount of foreign gene in silkworm body. 6. Farther discussion was carried out about the effect of fluorescer VBL onexpressive activity for foreign gene and about the synergia mechanism of VBL inperoral infection. The result showed there were no obvious effects of differentdosage of VBL on the expression of foreign gene in a certain degree (below 2%level) when VBL was fed together with artificial diet. On the other hand, distinctchanges were found in ultrastructure of midgut epithelia in silkworm larva. Thechanges mainly fastened on the reduced secretory function of microvillus, theexpanded endoplasmic reticulum, the decreasing number of ribosome attached toendoplasmic reticulum, and the disorganization of cell organs. The structure ofmidgut epithelia between the control plot and the treatment plot tended to samenessafter 48h when silkworms stopped ingesting diet with VBL. Therefore, conc...
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