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

A β-actin gene, Libβ-actinl, from the psocid, Liposcelis bostrychophila, was isolated, sequenced, and expressed in Escherichia coll. 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 B lastN search, the coding region shared the highest identity （97%） with Pediculus hurnanus 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 Libβ-actinl and homologs in other insect species. The 3＇ untranslated region （3＇ UTR） of the Libβ-actinl 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 Libβ-actinl was further analyzed in insecticide induced and control psocids. The results indicated that there was no significant difference in expression of Libβ-actinl between the induced and control groups, suggesting that Libβ-actinl may be an appropriate internal control for the gene expression profiling in this insect. Furthermore, Libβ-actinl was also heterologously expressed in Escherichia coli, which provided a basis to investigate the physiological functions of actin genes in the psocid.