Aminopeptidase N And Alkaline Phosphatase Expressed In Midgut Tissue Cells Of Bombyx Mori

Cry toxins, the crystal protein produced from Bacillus thuringiensis (Bt), is an importantbiological pesticide for lepidoteran pest control, it was widely applied in agriculturalproduction. However, silkworm (Bombyx mori) is a lepidoteran insect which was sensitive toBt toxin, the toxicosi acccidents of silkworm occurred frequently in the silkworm cultivationregion, which caused huge loss of sericulture production, also, the appplication of biologicalpesticide in silkworm raising region was restained. Therefore, one of solution is anti-Btbreeding of silkworm, which can coordinate the developmenatal paradox between sericultureproduction and crop pests controll.Aminopeptidase N (APN) is a kind of enzyme family which prefers to hydrolyze proteinor oligopeptide N-terminal neutral amino acid; Alkaline phosphatase (ALP) is a non-specificphosphomonoesterase, it is a very important group of regulatory enzyme. APNs are the wellknown receptor proteins to Bt-Cry in Lepidoptera. Research reports about the APN and ALPin insects were involved in the functional mechanism of Bt-resistant, which were found in theinsects study of Helicoverpa, Plutella xylostella, Heliothis virescens, etc. In addition, the APNin midgut tissue of helicoverpa armigera could combine with Cry toxins, and the mutation ofHaAPN gene was closely related to the formation of the cotton bollworm resistant varieties.However, there were few reports about the anti-Bt in the silkworm, and it was not clear in theBt-resistant mechanism of APN and ALP the combination action of BT-Cry toxins.In this study, bivoltine silkworm varieties (7001,7018,7025,7026,7027) andpolyvoltinism silkworm varieties (p50, qiufeng, rizhao,306,5124) were used, repectively.Then the expressions of APN gene family (APN1, APN2APN3, APN4, APN5) and ALP genein silkworm midgut as well as the distinct expressions in different cultivars of silkworm weredetected and analyzed using Real-Time PCR technology. The results showed:(1) Both theAPN gene family members and ALP gene were expressed in all silkworm strains, it indicatedthat APN and ALP genes were the common components of the silkworm;(2) Expressionlevels of APN gene in diverse silkworm strains were different, there were significantdifference between bivoltine strains and polyvoltinism strains, while the expressions in thesame voltinism had minor differences;(3) In the same silkworm strain, APN2, APN4andAPN5genes had higher expression levels, while APN1and APN3had relatively lowerexpression levels, which indicated that APN2, APN4and APN5were the main components of the Bombyx mori APN gene family;(4) Compared with the APN gene family members, theexpression level of ALP gene was generally higher in the same strain, however, itsexpressions were different between the voltinism strains, strains7001shared the highestexpression and strains306was the lowest one;(5) The expression levels of both APN andALP were lowest in strains306, suggesting that the expression levels of APN and ALP geneshad association with the disease resistance of silkworm strains.This results will contribute to further insight into the action mechanism of APN andALP enzymes, and provide the basis for silkworm breeding resistant to Bt.