Identification of isopeptidase activity in the midgut of insects： Purification, properties and nutritional ecology of a Hofmannophila pseudospretella （Lepidoptera： Oecophoridae） larval enzyme

A γ-glutamyl transpeptidase （isopeptidase） has been purified 580-fold to homogeneity from the midgut of keratinophagous larvae of Hofmannophila pseudospretella. The enzyme is a single polypeptide of molecular mass 80 kDa. The enzyme was identified by its hydrolytic activity against the synthetic substrate, γ-glutamyl-AMC, its molecular mass and inhibition profile compared to other γ-glutamyl transpeptidases. The enzyme is low or absent from most other insect digestive systems apart from other keratinophagous lepidopteran larvae and predatory carabids. While isopepfide bonds are present in high levels of the proteins in the diet of keratinophages, their presence in the diet of predatory beetles has not been established.

A Tool for the Treatment of Gastrointestinal Tumors: Micro- Ecological Immunotherapy

It has been proposed that the intestinal microbiota and gastrointestinal tumors are interdependent.Changes in the microbiota can cause dysfunction of the gastrointestinal tract,thereby promoting carcinogenic changes,leading to the occurrence of gastrointestinal tumors.Recent studies on intestinal microbiota have opened up a new area in intestinal micro-ecological immunotherapy.The intestinal microbiota is a double-edged sword.Gut microbes participate in carcinogenesis,but can also be used for immunotherapy.The intestinal microbiota is also regulated by the daily diet.Intestinal micro-ecological immunotherapy combines intestinal immune nutrition and intestinal ecological nutrition to make full use of the intestinal microbiota to strengthen nutritional support.Micro-ecological immunotherapy enhances the body’s immune function by providing energy,improving the functional state of tissues and organs,protecting the intestinal mucosal barrier and maintaining normal intestinal microbiota balance.This involves,to some extent,PD-1 and PD-L1.The microbiota is beneficial to improve the clinical efficacy of conventional anti-cancer therapy and to reduce the incidence of complications.At the same time,micro-ecological immunotherapy is itself active and effective in the perioperative treatment of tumors,which is of great significance for the prognosis of the patient.Gastrointestinal tumors are increasingly linked to intestinal microbiota,and various microbiota-related technologies and drugs have been developed.In the future,the intestinal microbiota may represent a screening marker for gastrointestinal tumors.In addition,clinicians may be able to prevent and treat cancers by changing the gene expression levels of certain microbiota,or by regulating the types of microbes present.

Seasonal diet and microbiome shifts in wild rhesus macaques are better correlated at the level of nutrient components than food items

Food supply is one of the major drivers of animal behavior,and the gut microbiome is an important mediator be-tween food supply and its effects on physiology.However,predicting the outcome of diet change on microbiome and consequences for the animal has proven extremely challenging.We propose this reflects processes occurring at different scales.Inadequate accounting for the multi-level complexity of nutrition(nutrients,foods,diets)obscures the diet influence on microbiome and subsequently animal.Here,we present a detailed year-round,multi-level analysis of diet and microbiome changes in a wild population of a temperate primate,the rhesus macaque(Macaca mulatta).Total daily food and nutrient intake of 6 male and 6 female macaques was monitored in each of the 4 sea-sons(total 120 days observations).For each individual,we found significant variation in the microbiome between all 4 seasons.This response was more strongly correlated with changes in macronutrient intake than with food items and much of the response could be explained at the level of 6 ecological guilds—sets of taxa sharing similar responses to nutrient intake.We conclude that study of diet,microbiome,and animal performance in ecology will more effectively identify patterns if diet is recorded at the level of nutrient intake.Although microbiome response to diet does show variation in species-level taxa in response to food items,there is greater commonality in response at the level of guilds.A goal for microbiome researchers should be to identify genes encoding microbial attributes that can define such guilds.