Study On Biological Function Of Microsporidian Surface Wall Protein

Microsporidian are a group of ubiquitous and unicellular protaza, and obligate intracellular parasites lacking mitochondria.Currently, There are approximately 150 described genera of microsporidia with over 1200 individual species. Microsporidian do a lot of harm to many agricultural fields,even human beings are also threatened. Historically,it had resulted in the thorough destruction of Silkworm industry in Europe; Morever,lately studies show that microsporidia has cause a variety of infections on human being.As shows above,it is urgent for researchers to learn more about this spectacular parasite.Here,we report the biological functions of its surface wall proteins such as protection,identification and infection,and also impose on the variation of surface wall proteins on another host—mulberry looper using the same microsporidium—Nosema.bombycis.The results as follows:First, study on protection of the surface wall protein1. The concentration of the protein extracting from the microsporidia by SDS methods is about 0.218mg/ml.Microsporidia remain morphologically intact by observation under microscope after dealing with the SDS method,and comparing the results of Coomassie Brilliant Blue R-250 dyeing with 1% eosin B dyeing ,it indicats that surface wall protein palys an important part in retaining an relatively stable inner environment of microsporidia2.N. bombycis which have been getten rid of spore surface wall protein by SDS prove to be less infectios than those who are intact.The infection rate reduces from 60% to 38.89%3.After treated with SDS,then exposed to NaCl solution with the concentration of 1%.2% and 4% respectively,the infection rate of microsporidia to silkworm is 37.78%.32.11% and 16.66% correspondingly.While untreated with SDS but with the same concentration of NaCl solution,the infection rate is 60%.51.11% and 67.77% respectively. Virulence control is 60%.4. After treated with SDS,then exposed two hours to three different temperature 35℃, 40℃and 45℃.infection rate is 21.11%, 16.66% and 11.11% respectively.While the same treatment but SDS show the infection rate is 43.33%, 37.78% and 40%. Virulence control is 60%.From the above experiment,we can get the conclusion that the spore wall protein of microsporidian spore is greatly relevant to capability of survival and infection of microsporidia.'Second, identification and infection of the spore wall protein of microsporidia1.Treated with rabbit serum, infection rate of microsporidia to silkworm is 79%, 82%, 87% and 82.3% respectively,showing there is hardly any influence on infection rate. Treated with rabbit serum toward N.bombycis for half an hour and an hour,the infection rate is 75.3% and 64% respectively.The virulence control is 80.7%2.Feeding the silkworm with distilled water and the spore wall protein solution formerly extracting with the SDS method, 12h and 24h, respectively, the infection rate is 51%.48.89% and 52%.47.78% respectively. The virulence control is 70%Above experiments show probably,treated with rabbit serum toward N.bombycis the infection rate is droping cIearly.Therefore,it is of great importance on the infection.But,we have no evidence to conform the identification function of this protein,and it need further study.Third, study on the variation and adaption of infection.1. Continuous cultivation in vivo after changing host may induce N.bombycis to adapt to change its initial features such as appearance.2.As three spore wall protein Nbl, Nb2 and Nb3 carry out electrophoresis.the bands of SDS-PAGE demonstrate Nb2 is much richer than Nbl and Nb3 ,and Nbl seems a little richer than Nb3 in total quantity of protein expression. A wide range of bands appear on the Gel,but it is apparently 5 main bands, 12KD, 17KD, 30KD, 33KD, 37KD, all of them taking on a remarkable difference in quantity.The quantity of 30KD of Nbl is the most abundant among the main protein in Nb3 and Nb2. and as to the other 4 main protein bands ,Nb2 is the much richer that the other two kinds of spore wall protein. The shape difference is the 67 KD and 70 KD protein bands of Nb2 ,which is exceptionally rich and Nbl is very low, especially.the quantity of Nb3 draw near zero; Additionally,34KD bands in Nb2 is hardly to be observed in that of Nbl and Nb3 .The complex results demonstrate that spore wall protein of microsporidia has changed in quantity.as well as in mumber after parasitizing in different kinds of host.