Sweet-tasting proteins demonstrate application potential in foods and beverages due to their high sweetness, low calorie, and non-toxicity. So far, eight natural sweet-tasting proteins have been obtained from natural plants. This paper briefs the sweetness properties of the eight proteins and the molecular mechanism of the sweetness, reviews the progress in the genetic engineering, heterologous expression, and molecular modification of three representative sweet-tasting proteins (monellin, brazzein, and thaumatin), and summarizes their expression yields in different hosts and sweetness properties. Lastly, this paper prospects the research, application, and industrial development of sweet-tasting proteins. This review provides a reference for further research and development of new proteinaceous sweeteners.
Plant Proteins/biosynthesis* ; Genetic Engineering/methods* ; Sweetening Agents/chemistry* ; Plants, Genetically Modified/metabolism*

Background::Pancreatic ductal adenocarcinoma (PDAC) is one of the main types of malignant tumor of the digestive system, and patient prognosis is affected by difficulties in early diagnosis, poor treatment response, and a high postoperative recurrence rate. Carbohydrate antigen 19-9 (CA19-9) has been widely used as a biomarker for the diagnosis and postoperative follow-up of PDAC patients. Nevertheless, the production mechanism and potential role of CA19-9 in PDAC progression have not yet been elucidated.Methods::We performed single-cell RNA sequencing on six samples pathologically diagnosed as PDAC (three CA19-9-positive and three CA19-9-negative PDAC samples) and two paracarcinoma samples. We also downloaded and integrated PDAC samples (each from three CA19-9-positive and CA19-9-negative patients) from an online database. The dynamics of the proportion and potential function of each cell type were verified through immunofluorescence. Moreover, we built an in vitro coculture cellular model to confirm the potential function of CA19-9. Results::Three subtypes of cancer cells with a high ability to produce CA19-9 were identified by the markers TOP2A, AQP5, and MUC5AC. CA19-9 production bypass was discovered on antigen-presenting cancer-associated fibroblasts (apCAFs). Importantly, the proportion of immature ficolin-1 positive (FCN1+) macrophages was high in the CA19-9-negative group, and the proportion of mature M2-like macrophages was high in the CA19-9-positive group. High proportions of these two macrophage subtypes were associated with an unfavourable clinical prognosis. Further experiments indicated that CA19-9 could facilitate the transformation of M0 macrophages into M2 macrophages in the tumor microenvironment. Conclusions::Our study described CA19-9 production at single-cell resolution and the dynamics of the immune atlas in CA19-9-positive and CA19-9-negative PDAC. CA19-9 could promote M2 polarization of macrophage in the pancreatic tumor microenvironment.

Oxidative Phosphorylation ; Acetylglucosamine ; Uridine Diphosphate N-Acetylglucosamine/metabolism*

The many-banded krait, Bungarus multicinctus, has been recorded as the animal resource of JinQianBaiHuaShe in the Chinese Pharmacopoeia. Characterization of its venoms classified chief phyla of modern animal neurotoxins. However, the evolutionary origin and diversification of its neurotoxins as well as biosynthesis of its active compounds remain largely unknown due to the lack of its high-quality genome. Here, we present the 1.58 Gbp genome of B. multicinctus assembled into 18 chromosomes with contig/scaffold N50 of 7.53 Mbp/149.8 Mbp. Major bungarotoxin-coding genes were clustered within genome by family and found to be associated with ancient local duplications. The truncation of glycosylphosphatidylinositol anchor in the 3'-terminal of a LY6E paralog released modern three-finger toxins (3FTxs) from membrane tethering before the Colubroidea divergence. Subsequent expansion and mutations diversified and recruited these 3FTxs. After the cobra/krait divergence, the modern unit-B of β-bungarotoxin emerged with an extra cysteine residue. A subsequent point substitution in unit-A enabled the β-bungarotoxin covalent linkage. The B. multicinctus gene expression, chromatin topological organization, and histone modification characteristics were featured by transcriptome, proteome, chromatin conformation capture sequencing, and ChIP-seq. The results highlighted that venom production was under a sophisticated regulation. Our findings provide new insights into snake neurotoxin research, meanwhile will facilitate antivenom development, toxin-driven drug discovery and the quality control of JinQianBaiHuaShe.

In recent years, there has been increasing evidence that nonalcoholic fatty liver disease (NAFLD) is a manifestation of a systemic metabolic disease in liver. However, limitations in the definition and diagnostic criteria of NAFLD could not fully and accurately describe the metabolic disorder. A consensus statement proposed renaming NAFLD to metabolic associated fatty liver disease (MAFLD). Compared with NAFLD, MAFLD links fatty liver disease with metabolic factors such as overweight or obesity and diabetes, and the diagnosis of the disease no longer excludes the presence of metabolic abnormalities in patients with alcohol consumption or other chronic liver diseases. The authors focus on definition changes of fatty liver disease, discuss the epidemiological changes from NAFLD to MAFLD and the relationship of MAFLD with liver fibrosis and extrahepatic diseases, and also the significance of MAFLD for public health.

Objective:To study the effect of insulin intraperitoneal injection on abnormal blood lipid intype 2 diabetic KKAy mice.Methods:Type 2 diabetic mice model was established by feeding high fat and high sugar diet. KKAy model mice were randomly divided into intraperitoneal injection group ( n=6), subcutaneous injection group ( n=6) and no-treatment group ( n=3). At the same time, healthy C57BL/6J mice were selected as normal group ( n=6), and healthy KKAy mice as disease-free group ( n=6). The treatment process was divided into two stages. The first stage consists of 6 weeks, in which the mice in the intraperitoneal and subcutaneous groups were treated with insulin intraperitoneally and subcutaneously respectively. The second stage consists of 4 weeks, in which the mice in intraperitoneal and subcutaneous groups were subcutaneously injected with insulin. The mice in the remaining 3 groups were not treated. The changes of related indicators were detected every two weeks, including body weight, fasting blood sugar, 2 hours after meal blood sugar, triglyceride (TG), total cholesterol (TC), high density lipoprotein cholesterol (HDL-C) and low density lipoprotein cholesterol (LDL-C). Results:Changing the injection solution in the medium term of the treatment had no effect on the body mass and blood sugar of KKAy mice with type 2 diabetes. Under this condition, the effect of intraperitoneal injection of insulin on HDL-C and LDL-C is significantly better than that of subcutaneous injection. Besides, both injection solutions are effective in regulating TG, but the effect of reducing total cholesterol is not obvious.Conclusions:The intraperitoneal injection of insulin has a certain effect on the blood lipid abnormality of type 2 diabetic KKAy mice. It can promote the increase of HDL-C, the decrease of LDL-C, and the decrease of TG.