Molecular mechanism of serine/threonine protein phosphatase 1 (PP1cα-PP1r7) in spermatogenesis of Toxocara canis.

Toxocariasis is one of the most important, but neglected, zoonoses, which is mainly caused by Toxocara canis. To better understand the role of serine/threonine protein phosphatase 1 (PP1) in reproductive processes of male adult T. canis, differential expression analysis was used to reveal the profiles of PP1 catalytic subunit α (PP1cα) gene Tc-stp-1 and PP1 regulatory subunit 7 (PP1r7) gene TcM-1309. Indirect fluorescence immunocytochemistry was carried out to determine the subcellular distribution of PP1cα. Double-stranded RNA interference (RNAi) assays were employed to illustrate the function and mechanism of PP1cα in male adult reproduction. Real-time quantitative PCR (qPCR) showed transcriptional consistency of Tc-stp-1 and TcM-1309 in sperm-producing germline tissues and localization research showed cytoplasmic distribution of PP1cα in sf9 cells, which indicated relevant involvements of PP1cα and PP1r7 in spermatogenesis. Moreover, spatiotemporal transcriptional differences of Tc-stp-1 were determined by gene knockdown analysis, which revealed abnormal morphologies and blocked meiotic divisions of spermatocytes by phenotypic aberration scanning, thereby highlighting the crucial involvement of PP1cα in spermatogenesis. These results revealed a PP1cα-PP1r7 mechanism by which PP1 regulates kinetochore-microtubule interactions in spermatogenesis and provided important clues to identify novel drug or vaccine targets for toxocariasis control.

Phylogenetic analysis of Mycoplasma suis isolates based on 16S rRNA gene sequence in China.

To perform phylogenetic analysis of Mycoplasma suis isolates derived from China to define the nature of this pathogen, nearly complete of 16S rRNA genes from Chongqing, Sichuan, Henan and Guangdong isolates were amplified by PCR and sequenced. The four sequences from the blood samples in this study, with other 17 Hemoplasmas sequences and related 3 mycoplasma sequences available in the GenBank, were aligned using Clustal X (version 1.83) sequences alignment program. Maximum parsimony, neighbor-joining and minimum evolution (MEGA 4.0) algorithms were used to create phylogenetic trees. Phylogenetic analysis of these sequences showed that all hemoplasma species were located within a single clade and were most closely related to M. pneumoniae group. The hemoplasma species were further subdivided into two distinct groups, one containing M.wenyonii, M.suis and Candidatus M. haemominutum and the other containing M. haemofelis and M. haemocanis. Within the former clade, four M.suis isolates from Mainland China and other M.suis species formed a monophyletic group in the tree. A tendency of clear geographical grouping of the isolate was evident.