Identification of Differentially Expressed Genes in the Salivary Gand of Rhipicephalus haemaphysaloides by the Suppression Subtractive Hybridization Approach

For the purpose of screening and analyzing the differentially expressed genes from the salivary gland of Rhipicephalus haemaphysaloides, two salivary gland-subtracted cDNA libraries of partially fed female ticks and fed male ticks were constructed using suppression subtractive hybridization （SSH）. A total of 247 female expression sequence tags （ESTs） and 168 male ESTs were obtained from the two SSH cDNA libraries. It is predicted that 25 female ESTs and 44 female ESTs contain the 5＂ and 3＂ ends, respectively, and that 53 male ESTs and 74 male ESTs contain the 5＂ and 3＂ ends, respectively. To identify the subtraction rate of the two SSH cDNA libraries, the RT-PCR method was used to test 24 female ESTs and 21 male ESTs selected randomly but not repeatedly. The results showed that there were 13 upregulated or differentially expressed genes in the partially fed salivary gland of the female R. haemaphysaloides and that the differentially expressed rate was 54%. In addition, they indicated that there were 9 upregulated or differently expressed genes in the fed salivary gland of the male R. haemaphysaloides and that the differentially expressed rate was 43%. Putative translations of 141 （57%） female ESTs and 125 （74%） male ESTs had similarity to GenBank sequences, and 32 （23%） female ESTs and 29 （23%） male ESTs exhibited similarity to tick proteins, which showed that most of the proteins in the libraries were mainly related to the feeding blood physiology of the ticks.

Proteomic Analysis of Proteins in the Salivary Glands of the Fed and Unfed Female Tick Rhipicephalus haemaphysaloides

Identification of differentially expressed salivary gland proteins between the fed and unfed female Rhipicephalus haemaphysaloides may obtain valuable functional molecules. In this study, comparative two-dimensional gel electrophoresis （2-DE） and mass spectrometry were used to separate and identify differentially expressed salivary gland proteins between the fed and unfed female R. haemaphysaloides. The soluble proteins from the salivary glands of fed and unfed female R. haemaphysaloides were separated by a sequential extraction method followed by 2-DE and 2-DE images. Image analysis of the gels revealed 1 096 ± 87 protein spots from the fed female ticks and 991 ±64 protein spots from the unfed female ticks. Among those protein spots, about 724 ±34 were present both in the fed and unfed female ticks. Fourteen spots from the fed ticks and six spots from the unfed ticks were selected for peptide mass fingerprinting （PMF） and sequencing assay by mass spectrometry （MS）. Bioinformatic analysis showed that a majority of the differentially expressed proteins were involved in signal transduction, metabolism, and transcriptional regulation. These differentially expressed proteins might be antigen candidates for the development of vaccines against the tick.