Molecular Characterization of Two Mitogen-Activated Protein Kinases: p38 MAP Kinase and Ribosomal S6 Kinase From Bombyx mori (Lepidoptera: Bombycidae), and Insight Into Their Roles in Response to BmNPV Infection

Muhammad, Azharuddin; Toufeeq, Shahzad; Yu, Hai-Zhong; Wang, Jie; Zhang, Shang-Zhi; Li, Bing; Li, Zhen; Yang, Li-Ang; Hu, Pei; Ma, Yan; Xu, Jia-Ping

To analysis tissue distribution of Bmp38 and BmS6K, different tissues including hemolymph, fat body, integument, head, midgut, and silk gland were collected for P50 and BC9 at 72 h after BmNPV challenge. After this, the RT-qPCR and western blot were performed. The Bmp38 was consecutively expressed in every tissue examined, with higher expression in the midgut, followed by the hemolymph. Furthermore, the Bmp38 expression levels in P50 (susceptible strain) and BC9 (resistant strain) were upregulated in the midgut, silk gland, integument, and hemolymph after BmNPV infection, whereas its expression level was downregulated in the fat body and head for P50 and was upregulated for BC9 after BmNPV infection (Fig. 6A) . Western blot results also showed that Bmp38 expression was relatively higher in the midgut, hemolymph, and fat body, which also validated our RT-qPCR results. However, no obvious hybrid band for Bmp38 was detected in the integument according to western blotting (Fig. 6B) . The RT-qPCR results indicated that BmS6K showed a different expression pattern with Bmp38. The BmS6K expression was also observed in every tissue examined, with the highest expression level in the hemolymph and midgut. The lowest expression was observed in the silk gland. Interestingly, unlike Bmp38, the expression between P50 (susceptible strain) and BC9 (resistant strain) of BmS6K was similar in the hemolymph and midgut, which was upregulated in P50 and BC9 after BmNPV infection. BmS6K expression level was downregulated in the head after BmNPV infection (Fig. 6C) . The translation level of BmS6K exposed that BmS6K had comparatively higher expression levels in the head, followed by the fat body. The translation data confirmed that BC9 had higher expression than P50 in the fat body after BmNPV infection (Fig. 6D ).