Steroid hormone 20-hydroxyecdysone disturbs fat body lipid metabolism and negatively regulates gluconeogenesis in Hyphantria cunea larvae.

The steroid hormone 20-hydroxyecdysone (20E) has been described to regulate fat body lipid metabolism in insects, but its accurate regulatory mechanism, especially the crosstalk between 20E-induced lipid metabolism and gluconeogenesis remains largely unclear. Here, we specially investigated the effect of 20E on lipid metabolism and gluconeogenesis in the fat body of Hyphantria cunea larvae, a notorious pest in forestry. Lipidomics analysis showed that a total of 1 907 lipid species were identified in the fat body of H. cunea larvae assigned to 6 groups and 48 lipid classes. The differentially abundant lipids analysis showed a significant difference between 20E-treated and control samples, indicating that 20E caused a remarkable alteration of lipidomics profiles in the fat body of H. cunea larvae. Further studies demonstrated that 20E accelerated fatty acid ß-oxidation, inhibited lipid synthesis, and promoted lipolysis. Meanwhile, the activities of pyruvate carboxylase, phosphoenolpyruvate carboxykinase, fructose-1,6-bisphosphatase, and glucose-6-phosphatase were dramatically suppressed by 20E in the fat body of H. cunea larvae. As well, the transcriptions of genes encoding these 4 rate-limiting gluconeogenic enzymes were significantly downregulated in the fat body of H. cunea larvae after treatment with 20E. Taken together, our results revealed that 20E disturbed fat body lipid homeostasis, accelerated fatty acid ß-oxidation and promoted lipolysis, but negatively regulated gluconeogenesis in H. cunea larvae. The findings might provide a new insight into hormonal regulation of glucose and lipid metabolism in insect fat body.

Most dominant roles of insect gut bacteria: digestion, detoxification, or essential nutrient provision?

BACKGROUND: The insect gut microbiota has been shown to contribute to the host's digestion, detoxification, development, pathogen resistance, and physiology. However, there is poor information about the ranking of these roles. Most of these results were obtained with cultivable bacteria, whereas the bacterial physiology may be different between free-living and midgut-colonizing bacteria. In this study, we provided both proteomic and genomic evidence on the ranking of the roles of gut bacteria by investigating the anal droplets from a weevil, Cryptorhynchus lapathi. RESULTS: The gut lumen and the anal droplets showed qualitatively and quantitatively different subsets of bacterial communities. The results of 16S rRNA sequencing showed that the gut lumen is dominated by Proteobacteria and Bacteroidetes, whereas the anal droplets are dominated by Proteobacteria. From the anal droplets, enzymes involved in 31 basic roles that belong to 7 super roles were identified by Q-TOF MS. The cooperation between the weevil and its gut bacteria was determined by reconstructing community pathway maps, which are defined in this study. A score was used to rank the gut bacterial roles. The results from the proteomic data indicate that the most dominant role of gut bacteria is amino acid biosynthesis, followed by protein digestion, energy metabolism, vitamin biosynthesis, lipid digestion, plant secondary metabolite (PSM) degradation, and carbohydrate digestion, while the order from the genomic data is amino acid biosynthesis, vitamin biosynthesis, lipid digestion, energy metabolism, protein digestion, PSM degradation, and carbohydrate digestion. The PCA results showed that the gut bacteria form functional groups from the point of view of either the basic role or super role, and the MFA results showed that there are functional variations among gut bacteria. In addition, the variations between the proteomic and genomic data, analyzed with the HMFA method from the point of view of either the bacterial community or individual bacterial species, are presented. CONCLUSION: The most dominant role of gut bacteria is essential nutrient provisioning, followed by digestion and detoxification. The weevil plays a pioneering role in diet digestion and mainly digests macromolecules into smaller molecules which are then mainly digested by gut bacteria.

Molecular characterization of diapause hormone and pheromone biosynthesis activating neuropeptide from the black-back prominent moth, Clostera anastomosis (L.) (Lepidoptera, Notodontidae).

Using a strategy of rapid amplification of cDNA ends, the cDNA of diapause hormone (DH) and pheromone biosynthesis activating neuropeptide (PBAN) was cloned from the head of Clostera anastomosis (L.). The Cloan-DH-PBAN cDNA contains an open reading frame encoding a 196-amino acid preprohormone, from which five putative FXPRL peptides, DH, PBAN, alpha-SGNP(SGNP, suboesophageal ganglion neuropeptide), beta-SGNP and gamma-SGNP, are released. Comparing the deduced amino acid sequences from cDNAs of these five FXPRL peptides to those known from other insects, Cloan-DH shows highest similarity of 93.1% to that from Agrotis ipsilon, Cloan-PBAN 93.9% to those from Helicoverpa armigera, Helicoverpa zea and Helicoverpa assulta, which show the highest similarity to species of Noctuidae. Phylogenetic analysis revealed that the Cloan-DH-PBAN gene is relatively closely related to those from Noctuoidea, but distant from those from Tortricoidea, Yponomeutoidea and Bombycoidea species. The DNA sequence encoding Cloan-DH-PBAN was cloned by PCR, which is 3698bp in size and comprises six exons interspersed by five introns. Developmental expression of the DH-PBAN transcripts in the head was also showed by a semi-quantitative RT-PCR method, which was relatively low in larvae and remained low in pupae of both sexes, increased sharply in adults of both sexes.

Functional characterization of ASTC (allatostatin C) and ASTCC (allatostatin double C) in Clostera anastomosis (Lepidoptera: Notodontidae).

ASTC (allatostatin C) and ASTCC (allatostatin double C) are two neuropeptide genes that encode allatostatin C-like peptides. Whether these peptides inhibit or have other effects on juvenile hormone (JH) synthesis in the corpora allata remains in question. The juvenile hormone acid O-methyltransferase (JHAMT), a key gene in the JH biosynthesis pathway, was selected to study the effects of ASTC and ASTCC on juvenile hormones. In this study, we first characterized the expression patterns and correlations between ASTC and ASTCC in Clostera anastomosis under natural conditions, and then the functions of these two genes were investigated by RNAi. The results showed the expression of JHAMT was strongly positive correlated with ASTC and ASTCC in the heads of larvae after ASTC and ASTCC were knocked down simultaneously, while negative correlations were found in the heads of female adults. These results suggest that both ASTC and ASTCC may stimulate JH biosynthesis in larvae while inhibit in female adults of C. anastomosis. And after either ASTC or ASTCC was knocked down alone, the correlation between the two genes were positive, indicating ASTC and ASTCC may function dependently in female heads. In addition, simultaneous suppression of ASTC and ASTCC increased the mortalities of larvae and pupae.

[Risk factors of gastric cancer in Wuwei City---an endemic region of gastric cancer].

BACKGROUND & OBJECTIVE: Researches show that epidemiologic factors of gastric cancer include living habit, eating moldy food and pickles, dystrophy, lack of microelements, and inherit, etc. This study was to explore universalities of these factors in Wuwei, a city in northwest China with high incidence of gastric cancer, and provide evidences for the first-prevention of gastric cancer. METHODS: Family histories of the residents in Wuwei City were investigated with case-control method. Separating ratio and heredity degree of gastric cancer were calculated with Li-Mantel-Cart method and Falconer's regression method. Chronic gastritis patients were followed-up by home-visit, gastroscopy, and pathology. Cancerigenic fungi and volatility N-nitrosate compounds in residents' meal, Helicobacter pylori (Hp) in gastric mucosa, and total content of vitamin C in 293 healthy adults' serum were detected by culture, authentication, and laboratory examinations. RESULTS: In Wuwei City, the separating ratio of gastric cancer was 0.077; the heredity degree of first-degree relatives was 22.91%u cancerization rate of year in person of atrophic gastritis crowd was 1.09%. Eight kinds of nitrosamine and 14 kinds of cancerigenic fungi were detected from residents' meal. Total content of vitamin C in serum of the 293 healthy adults in summer was (5.74+2.79) mg/L. Positive rate of Hp in gastric mucosa of the residents was 67%. CONCLUSION: The major extrinsic factors of gastric cancer in Wuwei City include various strong carcinogens existing in residents' meal and lack of vitamin Cu its intrinsic factors include infection of Hp, atrophic gastritis (especially atypical hyperplasia), and heritage susceptibility.