Studies On Cladistic Systemics And EST Isozymes Of Unionicolid Mites

In this paper, cladistic systematic analysis was realized by neans of morphological character for 15 known species of the genus Unionicola from China, genetic differentiation of unionicolid mites of 3 species, and correlativity between mites and Cristaria plicata was analyzed to utilize esterase isozyme, eggs of unionicolid mite effect on tissues of host bivalve was observed through tissue slice of Cristaria plicata.Thirty-five characters were chosen for the cladistic analysis on unionicolid mites of 15 species. The results indicated that the unionicolid mites were assembled into two groups by the ventral finger-tubercle of P-IV. U. imamurai appeared to be the most ancestral species with short spur of P-IV which is similar to the outgroup. The morphology of anterior acetabular plates of females impacted congregation on those species in the subgenus Pentatax and Polyatax. Thereout, it was supposed that the ventral finger-tubercle of P-IV and anterior acetabular plates of females may also be used as discriminative characters of the subgenus in the Unionicola. The simple structure of acetabula is one of plesiomorphic characters, so it appeared that U. affinis with five pairs of acetabula was much more primitive than U. crassipes with six pairs of acetabula. The female water mites with a pair of acetabular plates of the subgenus Parasitatax and Wolcottatax was sister group together. The results supported Vidrine's revision for the subgenus Parasitatax that Wolcottatax was divorced from the subgenus Parasitatax.Comparative analysis on the isozyme patterns of Esterase for gill tissue of Cristaria plicata and unionicolid mites of 3 species was carried out to prode into their distribution by Polyacrylamide Gel Electrophoresis (PAGE). Esterase existed in samples with a little specificity. Electrophoresis result showed that there is 6 different esterase bands in unionicolid mites, and 3 esterase bands existed in each of unionicolid mites, 2b was special esterase bands of Unionicla arcuata, 4 esterase bands of U. ypsilophora was similar to other unionicolid mites, 2a esterase band was defect in U. agilex. Therefore, 2a and 2b esterase bands might be regarded characteristic zymogram as classification of unionicolid mites, EST isozyme of gill tissue from Cristaria plicata had 5 EST bands of different expression, 3 EST bands of those were resembled to unionicolid mites, So it was inferred that the coevolution might also exist between Cristaria plicata and unionicolid mites.The histopathological effect of Unionicola arcuata eggs on different tissues in Cristaria plicata was studied by comparing five tissues, including mantle, gill, foot, labial palpus and water pipe as well, between healthy (uninfected) and ill (infected) bivalve using the wax section technology. Results showed that in tissues of the healthy bivalve, epithelial cells arrange in normal order and connective tissues distribute homogeneously, while in ill bivalve, a compact cyst was found to form around eggs, making its peripheral tissues be pressed and epithelial or connective cells be out of shape, and hemocytes be aggregated. It's suggested that U. arcuata eggs be harmful to several different tissues of C. plicata, and lead to certain obvious histopathological effect on them.