Differential gene expression profiling in the developed ovaries between the parthenogenetic and bisexual female rice water weevils, Lissorhoptrus oryzophilus Kuschel (Coleoptera: Curculionidae)

RNA interference of tubulin genes has lethal effects in Mythimna separate

RNAi (RNA interference) is a technology for silencing expression of target genes via sequence-specific double-stranded RNA (dsRNA). Recently, dietary introduction of bacterially expressed dsRNA has shown great potential in the field of pest management. Identification of potential candidate genes for RNAi is the first step in this application. The oriental armyworm, Mythimna separata Walker (Lepidoptera: Noctuidae) is a polyphagous, migratory pest, and outbreaks have led to severe crop damage in China. In the present study, two tubulin genes were chosen as target genes because of their crucial role in insect development. Both Msα-tubulin and Msβ-tubulin genes are expressed across all life stages and are highly expressed in the head and epidermis. Feeding of bacterially expressed dsRNA of Msα-tubulin and Msβ-tubulin to third-instar larvae knocked down target mRNAs. A lethal phenotype was observed with knockdown of Msα-tubulin and Msβ-tubulin concurrent with reduction in body weight. Bacterially expressed dsRNA can be used to control M. separata, and tubulin genes could be effective candidate genes for an RNAi-based control strategy of this pest.

Full-length cloning, sequence analysis and expression detection of the β-tubulin gene from the Chinese gall aphid (Schlechtendalia chinensis)

Some insect galls are formed on sumac plants by certain aphid species and have been used for medicinal and chemical purposes as they are rich in tannins. The most prominent species among gall aphids in China is Schlechtendalia chinensis, which formed horn-shaped galls on the winged rachis of Rhus chinensis. S. chinensis has a complex life cycle, with a switch of hosts between R. chinensis and certain mosses, and a switch of sexual and asexual reproduction (cyclical parthenogenesis). We have cloned a full-length cDNA of the β-tubulin gene from S. chinensis, using qPCR and RACE. This cDNA has 1606 base pairs with a 251 bp 5'-untranslated region (5'-UTR) and a 15 bp 3'-untranslated region (3'-UTR). The gene encodes a protein with 376 amino acids residues. The expression levels of the β-tubulin gene in S. chinensis were investigated among fundatrigeniae and overwintering larvae rearing under either natural conditions, or at 7.5 °C and 18 °C. No significant differences (P > 0.01) in gene expression levels were found in insects under these conditions. It is indicates that the β-tubulin gene is highly conserved and then it may be used as a reference for further research in gene expression and reproduction determination in this important aphid.

Characterisation and expression analysis of UBC9 and UBS27 genes in developing gonads of cicindelids (Coleoptera: Cicindelidae)

Ubiquitin and small ubiquitin-like modifiers (SUMO) are post-translational modifiers essential in a variety of cellular processes, including gametogenesis. SUMO-conjugating enzyme (UBC9) and the ubiquitin ribosomal fusion protein UBS27 have been characterised in several model species. However, their expression in coleopteran remains unstudied. In this study, UBC9 and UBS27 genes have been characterised in the tiger beetle Cicindela campestris for the first time. Bioinformatic analysis showed that the Cc-UBC9 gene encoded a 159 amino acid protein with a predicted molecular weight of 18.18kDa, and the Cc-UBS27 gene encoded a 156 amino acid protein with a predicted molecular weight of 17.71kDa. Selection analyses carried out in several cicindelid species revealed that both genes were affected by purifying selection. Real time quantitative PCR analysis demonstrated that Cc-UBC9 and Cc-UBS27 were expressed in different tissues. The highest expression on both genes was found in the ovary and testis, and there were differential expression levels between immature and mature stages of testis development. The expression patterns of Cc-UBC9 and Cc-UBS27 suggest that these genes play important roles in gametogenesis in C. campestris. This information is relevant to better understand the reproductive process in cicindelids and the function of ubiquitin and small ubiquitin-related modifier genes in the Coleoptera.

Cloning and expression analysis of a G-protein α subunit--Gαo in the rice water weevil Lissorhoptrus oryzophilus Kuschel

The open reading frame (ORF) encoding a novel G protein α subunit, Lo Gα(o), was cloned from the parthenogenetic rice water weevil, Lissorhoptrus oryzophilus Kuschel (Coleoptera: Curculionidae). The Lo Gα(o) ORF encodes a protein of 354 amino acid residues. The deduced protein sequence shares high homology with Gα(o) from other species. The expression patterns of Lo Gα(o) in various adult tissues were indicated by real-time quantitative PCR and Western blot. The results showed that Lo Gα(o) mRNA was expressed at similar levels in tissues except relative high levels in the antennae of adult, and Lo Gα(o) protein of an apparent molecular mass of about 40 kDa was expressed in various tissues of the adult. Immunocytochemical localization showed that Lo Gα(o) was mainly expressed in the dendrites of the trichoid sensilla in the antenna of the weevil. The tissue and cellular localization of Lo Gα(o) suggests that Lo Gα(o) may take a part in signal transduction of olfactory/gustatory.