RESUMO
Wood-feeding insects depend heavily on the secretion of a combination of cellulases, mainly endoglucanases and other glucanases such as exoglucanases and xylanases, to achieve efficient digestion of the cellulose of cellulosic materials. In this paper, we report a novel cellulose Bh-EGaseI belonging to the glycoside hydrolase family 45(gh45-1) obtained from the beetle Batocera horsfieldi. The Bh-EGaseI gene spans 714 bp and consists of three exons coding 237 amino acid residues. The cDNA encoding Bh-EGaseI was expressed as 25 KDa in baculovirus-infected Bombyx mori larvae. The expression products of Bh-EGaseI from larval hemolymph showed a specific enzymatic activity of approximately 1030.87 IU per mg. The enzyme was active over a wide range of pH and temperatures; optimal activity was observed at 40 °C and pH 4.0. The effects of ions on Bh-EGaseI activity were also studied, and results indicated that activity decreased to different extents upon addition of ions. Investigations on Bh-EGaseI facilitate their potential application in the production of bioenergy and biomaterials from cellulosic biomass in the future.
Assuntos
Celulase , Besouros , Proteínas de Insetos , Animais , Celulase/biossíntese , Celulase/química , Celulase/genética , Celulase/isolamento & purificação , Clonagem Molecular , Besouros/enzimologia , Besouros/genética , Expressão Gênica , Proteínas de Insetos/biossíntese , Proteínas de Insetos/química , Proteínas de Insetos/genética , Proteínas de Insetos/isolamento & purificação , Proteínas Recombinantes/biossíntese , Proteínas Recombinantes/química , Proteínas Recombinantes/genética , Proteínas Recombinantes/isolamento & purificaçãoRESUMO
The "Ming" lethal egg mutant (l-em) is a vitelline membrane mutant in silkworm, Bombyx mori. The eggs laid by the l-em mutant lose water, ultimately causing death within an hour. Previous studies have shown that the deletion of BmEP80 is responsible for the l-em mutation in silkworm, B. mori. In the current study, digital gene expression (DGE) was performed to investigate the difference of gene expression in ovaries between wild type and l-em mutant on the sixth day of the pupal stage to obtain a global view of gene expression profiles using the ovaries of three l-em mutants and three wild types. The results showed a total of 3,463,495 and 3,607,936 clean tags in the wild type and the l-em mutant libraries, respectively. Compared with those of wild type, 239 differentially expressed genes were detected in the l-em mutant, wherein 181 genes are up-regulated and 58 genes are down-regulated in the mutant strain. The Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis results showed that no pathway was significantly enriched and three pathways are tightly related to protein synthesis among the five leading pathways. Moreover, the expression profiles of eight important differentially expressed genes related to oogenesis changed. These results provide a comprehensive gene expression analysis of oogenesis and vitellogenesis in B. mori which facilitates understanding of both the specific molecular mechanism of the 1-em mutant and Lepidopteran oogenesis in general.
