Identification and Expression of a β-actin Gene from Liposcelis bostrychophila Badonnel (Psocoptera: Liposcelididae)

A beta-actin gene, Lib beta-actin1, from the psocid, Liposcelis bostrychophila, was isolated, sequenced, and expressed in Escherichia coli. The cDNA sequence was 1 281 bp in length and contained an open reading frame of 1 131 bp encoding 376 amino acids with a predicted molecular weight of 41.82 kDa. According to a BlastN search, the coding region shared the highest identity (97%) with Pediculus humanus actin 5C, while the deduced amino acid sequence was completely identical to a mutant of Drosophila melanogaster actin 5C. Comparison of the nucleotide and deduced amino acid sequences confirmed the high similarity between Lib beta-actin1 and homologs in other insect species. The 3' untranslated region (3' UTR) of the Lib beta-actin1 mRNA had a high A+U content (approximately 75%) and contained three repeats of the AUUUUUA and AUUUA motifs, which may play a role in regulating mRNA decay. The expression of Lib beta-actin1 was further analyzed in insecticide induced and control psocids. The results indicated that there was no significant difference in expression of Lib beta-actin1 between the induced and control groups, suggesting that Lib beta-actin1 may be an appropriate internal control for the gene expression profiling in this insect. Furthermore, Lib beta-actin1 was also heterologously expressed in Escherichia coli, which provided a basis to investigate the physiological functions of actin genes in the psocid.