A b-actin gene,Libb-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 Libb-actin1 and homologs in other insect species.The 3' untranslated region(3' UTR) of the Libb-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 Libb-actin1 was further analyzed in insecticide induced and control psocids.The results indicated that there was no significant difference in expression of Libb-actin1 between the induced and control groups,suggesting that Libb-actin1 may be an appropriate internal control for the gene expression profiling in this insect.Furthermore,Libb-actin1 was also heterologously expressed in Escherichia coli,which provided a basis to investigate the physiological functions of actin genes in the psocid.
