Acetyl coenzyme A carboxylase modulates lipogenesis and sugar homeostasis in Blattella germanica

Lipid and sugar homeostasis is critical for insect development and survival.In this study,we characterized an acetyl coenzyme A carboxylase gene in Blattella germanica(BgACC)that is involved in both lipogenesis and sugar homeostasis.We found that BgACC was dominantly expressed in the fat body and integument,and was significantly upregulated after molting.Knockdown of BgACC in 5th-instar nymphs did not affect their normal molting to the next nymphal stage,but it caused a lethal phenotype during adult emergence.BgACC-RNA interference(RNAi)significantly downregulated total free fatty acid(FFA)and triacylglycerol(TAG)levels,and also caused a significant decrease of cuticular hydrocarbons(CHCs).Repression of BgACC in adult females affected the development of oocytes and resulted in sterile females,but BgACC-RNAi did not affect the reproductive ability of males.Interestingly,knockdown of BgACC also changed the expression of insulin-like peptide genes(BglLPs),which mimicked a physiological state of high sugar uptake.In addition,BgACC was upregulated when B.germanica were fed on a high sucrose diet,and repression of BgACC upregulated the expression of the glycogen synthase gene(BgGlyS).Moreover,BgACC-RNAi increased the circulating sugar levels and glycogen storage,and a longevity assay suggested that BgACC was important for the survival of B.germanica under conditions of high sucrose uptake.Our results confirm that BgACC is involved in multiple lipid biogenesis and sugar homeostasis processes,which further modulates insect reproduction and sugar tolerance.This study benefits our understanding of the crosstalk between lipid and sugar metabolism.

A novel ascosporogenous yeast species,Zygosaccharomyces siamensis,and the sugar tolerant yeasts associated with raw honey collected in Thailand

Diversity of yeasts in association with bees and their food sources has been explored during the last decade.In Thailand,there has been no study of yeast identification in honey and bees.Hence,a total of 186 yeast strains were isolated from 37 honey samples of 12 different bee species.On the basis of morphological and physiological characteristics,55 representative strains were chosen and identified by sequence analysis of the 26S rDNA D1/D2 domain and the ITS region.The data were compared with the published sequences and the results showed the occurrence of 19 ascomycetous and 1 basidiomycetous yeast species.Six strains of the new species were isolated.Phylogenetic analysis of the 26S rDNA D1/D2 sequence revealed that they were conspecific and most closely related to Zygosaccharomyces mellis.Based on the ITS sequence,the new species was clustered with the type"and clearly distinguished from the type!.Sequence analysis of combined ITS-26S rDNA D1/D2 showed similar results.The occurrence of these two types,with a divergence of more than 1%in their sequences,and low DNA relatedness among them suggested that members of the typeβcan be regarded as separate species.An analysis of the morphological and physiological characteristics was performed.Ascospore formation was observed on acetate agar and Gorodkowa agar.The new Zygosaccharomyces species differed physiologically from Z.mellis in 4 assimilation tests.This data supports the hypothesis that the new species,Zygosaccharomyces siamensis,is a novel ascosporogenous yeast.The type strain is JCM 16825T(=CBS 12273T)and a description is given here.