Primary Research On Innate Immune Related Genes In Malpighian Tubule From The Silkworm Larvae, Bombyx Mori

The silkworm, Bombyx mori, is a typical model system for Lepidoptera and is also an important economic insect, which should be reared by mankind. Research on the silkworm immune-related genes will help us understand not only the molecular mechanisms of silkworm immune respose, but also the diversity of insect immunity.Recently, Drosophila has revealed the Malpighian tubule (MT) plays a signification role in immunity; the MT are capable of sensing bacterial challenge, and mounting an effective killing response by secretion of antimicriobial peptides, entirely independent of the fat body, the canonical immune tissue. Based on the achievements from Drosophila MT, we start to investigate the immunity function of the MT in silkworm.In order to investigate the proteomics and immune function of the MT in silkworm, the proteins of MT, which infected with BmNPV-EGFP, were separated by using the method of the Two-dimensional polyacrylamide gel electrophoresis (2-D). Fourteen protein spots that increased dramatically in the infected ones were excised and supplied to identify furtherly by means of matrix assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOFMS). And 10 spots had been identified successfully,which included NADPH-specific isocitrate Dehydrogenase, Panthenol-cytochrome C reductase core proteinⅡ, protein disulfide isomerase, pyruvate dehydrogenase E1βsubunit complexes, aspartate aminotransferase, acetyl coenzyme A acetyl sulfur lyase, 3-hydroxy-isobutyrate dehydrogenase, hydroxy-pyruvate isomerase / nitric oxide synthase, ATP synthaseβsubunit of proton transfer, and ATP synthase. The ATP synthaseβsubunit of proton transfer which in these spots had already been reported and this paper will have a further research on another protein named as Nitric oxide synthase (BmNOS).Inducible nitric oxide is the key synthase for NO, and NO is an important effector Molecule of macrophages that involved in immune regulation and host defense.In this paper, the expression level of BmNOS gene in MT was investigated by quantitative real-time PCR method at different development stages of silkworm treated with BmNPV or LPS, respectively.The results showed that the expression level of BmNOS gene was dramatically increased by 7 times at 3 hr post infection of BmNPV, and by 25 times at both 3 hr and 6 hr post treatment of LPS, compared with that of the respective control. Hence the expression level of the control and treatment was similar. The above results suggested that BmNOS may play an important role in innate immune response of malpighian tubule of the silkworm.