Impact Of Hyperproteinemia On Remodeling And Function Of Fat Body In Bombyx Mori

Hyperproteinemia is a common metabolic disease in clinics. The research of related pathogenesis remains unknown because there is no reliable animal models about hyperproteinemia. We have successfully constructed two animal models of hyperproteinemia with silkworm, and we found there were remodeling and physiological dysfunctions during larva-pupa metamorphosis in fat body. Therefore, this study focused in the mechanism of the effect of hyperproteinemia on fat body remodeling and the reproductive function of the silkworm, Bombyx mori. The results are as follows:1 Hyperproteinemia induced remodeling abnormalities of silkworm fat body during metamorphosisTransgenic mutant silkworm named TBH constructed by the laboratory is a normal subculture of mild hyperproteinemia genetic strain. The middle and posterior silk gland of TBH larvae developted asymmetrically, leading to abnormal secretion of synthesized silk protein and delay of silk glands degeneration during larvae-pupal metamorphosis, and further dramatic increase in hemolymph protein concentration at about 1 week after pupation. Another way to quickly construct a severe hyperproteinemia silkworm model(abbreviated as animal model, AM) is to plugging orifice of spinneret of silkworm with low-melting wax, preventing the secretion of storage protein in the silkgland. Eventually leading to hemolymph protein concentration maintained at an extremely high level during the whole pupal stage.Morphological investigation results showed that, fat body dissociation of mild TBH silkworm began earlier than wild type, and the period of dissociation and remodeling extended. Fat body of severe AM silkworm dissociated later than the control group and the process significantly prolonged and remodelling difficultly.After investigation of the expression of fat body remodeling-ralated gene Bm Atg6、Bm Atg8 and Bm Dronc by Real-time PCR, we found the expression of these three genes were significantly lower than control in the silkworm fat body of both models during metamorphosis. Further cell lysosomes staining and nuclei stained with DAPI results showed that a certain degree of autophagy and apoptosis obstacles occurred in fat body cells of both the two kinds of hyperproteinemia silkworm.2 Effects of hyperproteinemia on physiological functions of silkworm fat body during metamorphosisThe results of HPLC showed that significant changes occurred in the content of multiple free amino acids of hyperproteinemia silkworm fat body, there also has been abnormality in the enzyme activities of amino acids metabolism-related GPT、GOT. ROS increased in fat body of hyperproteinemia silkworms suggesting cellular oxidative stress level rised, thus activities of SOD and CAT increasing to catalyze the ROS transforming into hydrogen peroxide and decomposing hydrogen peroxide.Investigation of Vg synthesis in fat body during metamorphosis showed that, Vg m RNA level of hyperproteinemia silkworm fat body was significantly lower than control, suggesting that obstacles arised in the protein synthesis of Vg necessary for reproductive development of females; further observation of ovarian development showed that, weight of ovarian and gonadosomatic index of hyperproteinemia silkworm were significantly lower than control. The number of adults spawning of mild AM(plugging orifice of spinneret after spinning for 6h) reduced, and the nonfertilized eggs increased.