文摘
Sp?tzle gene codes for a NGF-like protein, it involves in the embryonic development and innate immune response of insects and other invertebrate. In dorsal ventral axis differentiation, proSp?tzle is activated by serine endoproteases Easter and then binds to the Toll receptor in ventral axis of oocyte which initiates the ventral axis development. Besides, it could also be activated by another protease named Sp?tzle-processing enzyme (SPZ) to mediate Toll pathway which involves in innate immune response in fungal and Gram-positive bacterial infection of invertebrate. In this paper, a full-length cDNA of Sp?tzle was firstly isolated from Artemia sinica which belonged to Sp?tzle-4 family. The expression of Sp?tzle was investigated at various stages during the embryonic development of A. sinica using real-time PCR and immunohistochemistry assays. The result showed that the high expression level of Sp?tzle appeared at 7 and 10 days of the embryo. A gradual increased level of Sp?tzle transcript occurred after being challenged with Gram-positive bacteria. Immunohistochemistry assay showed that Sp?tzle was mainly expressed in the cephalothorax and on the alimentary canal surface during embryonic development. This new Sp?tzle member showed a constitutive and regional expression during the embryonic development of A. sinica. It may play an important role in dorsal–ventral differentiation at the early development stages and in immune response pathway at the pseudoadult and adult stage, as well as during infection.