Cloning and expression analysis of beta-tubulin gene in Tetrahymena pyriformis following infection of the guppy

Abstract

Tetrahymenosis is caused by the ciliated protozoan Tetrahymena and is responsible for serious economic losses to the aquaculture industry worldwide. However, information regarding the molecular mechanism leading to tetrahymenosis is limited. In previous transcriptome sequencing work, it was found that β-tubulin gene was significantly expressed in T. pyriformis during its infected fish, we speculated that β-tubulin involved in Tetrahymena piriformis infecting fish. Herein, the potential biological function of the β-tubulin gene in Tetrahymena species when establishing infection in guppies was investigated by cloning the full-length cDNA of T. pyriformis β-tubulin gene (TUBB). The full-length cDNA of TUBB was 1873 bp, and the ORF occupied 1134 bp, whereas 5' UTR 434 bp, and 3' UTR 305 bp whose poly (A) tail contained 12 bases. The predicted protein encoded by TUBB had a calculated molecular weight of 42.26 kDa and pI of 4.48. Moreover, secondary structure analysis and tertiary structure prediction of TUBB protein were also conducted. In addition, morphology, infraciliature, phylogeny, and histopathology of T. pyriformis isolated from guppies from a fish market in Harbin were also investigated. Furthermore, qRT-PCR analysis and experimental infection assays indicated that the expression of TUBB resulted in efficient cell proliferation during infection. Collectively, our data revealed that TUBB is a key gene involved in T. pyriformis infection in guppies, and the findings discussed herein provide valuable insights for future studies on tetrahymenosis.