Effect of Nosema bombycis on apoptosis of BmN cells and expression level of BmIAPs

Abstract:

[Objective] To study the effect of Nosema bombycis on the apoptosis of BmN cells and the expression level of BmIAPs under the condition without external apoptosis-inducing factor.[Methods] We observed the change of BmN cells at different times by using microscope after inoculation with N. bombycis. The relative expression level of BmCyt c in the N. bombycis infected BmN cells was detected by using real-time PCR. We searched databases of silkworm genome and Pfam finding information of Bombyx mori inhibitor of apoptosis proteins (BmIAPs). Real-time PCR was used to demonstrate the relative expression level of BmIAPs in N. bombycis infected BmN cells.[Results] Compared with the normal BmN cells, BmN cells infected by N. bombycis had no obviously change at 5 d post-inoculation. The growth of BmN cells was influenced by N. bombycis at 7 d post-inoculation. The vacuolization and apoptosis were found in most BmN cells at 12 d. However, the phenomenon was not found in N. bombycis infected BmN cells. Moreover, the relative expression level of BmCyt c was suppressed in N. bombycis infected BmN cells at most of the time, except for 7 d. The expression of BmCyt c was lowest compared with control groups (P<0.01) at 10 d and 12 d post-inoculation. Through searching the databases, we obtained four BmIAPs, including BmIAP-1, BmIAP-2, BmSurvivin-1 and BmSurvivin-2. The results of real-time PCR indicated that the relative expression level of BmIAP-1 and BmSurvivin-1 had up-regulating tendency at 10 d and 12d post-inoculation, especially at 12 d post-inoculation. But, BmIAP-2 and BmSurvivin-2 had down-regulated expression at most times.[Conclusion] Under the condition without external apoptosis-inducing factor, growth and apoptosis of BmN cells can be influenced by N. bombycis. According to the results of real-time PCR, we speculated that BmIAP-1 and BmSurvivin-1 may play a certain role in regulating the apoptosis of BmN cells infected by N. bombycis.