Comparison of MFGM N-glycoproteomes among human and bovine colostrum and mature milk reveals diverse compositions and biological functions among them.

Milk fat globule membrane (MFGM) proteins have recently gained increasing attention, due to their significant biological function. However, the glycosylation of proteins in human MFGM during lactation has not been studied in detail. In this study, through mass spectroscopy-based N-glycoproteomics, we analyzed protein glycosylation of human MFGM. A total of 912 N-glycosylation sites on 506 N-glycoproteins were identified in human colostrum and mature milk MFGM. Among them, 220 N-glycoproteins with 304 N-glycosylation sites were differentially expressed in colostrum and mature milk MFGM. Gene Ontology (GO) analysis revealed various biological processes, cellular components, and molecular functions of the differentially expressed N-glycoproteins. Specifically, these glycoproteins were involved in biological processes such as single-organism processes, biological regulation, regulation of biological processes, response to stimulus and localization; were cellular components in organelles, membranes, and the extracellular region; and had different molecular functions such as protein binding, receptor activity, and hydrolase activity. KEGG pathway analysis suggested that the majority of the differentially expressed N-glycoproteins were associated with phagosome, cell adhesion molecule and some disease-related pathways. Our results provide an in-depth understanding of the quantitative changes in N-glycosylation of proteins in human colostrum and mature MFGM, and extend our knowledge of the N-glycoproteome and of the distribution of N-glycosylation sites in human MFGM during lactation, providing insight into the biological functions of the highlighted glycoproteins.

Three new species, Calocybe aurantiaca, C. convexa, and C. decolorata, are described based on collections made in Shenyang City, Liaoning Province, China. The main characters of C. aurantiaca are its orange-yellow sporocarps and small and smooth basidiospores. Calocybe convexa is characterized by its orange-buff pileus, very small basidiospores, and tortuous stipe, whereas C. decolorata is mainly characterized by its gills that turn blue when bruised. The sequences of nuc rDNA ITS1-5.8S-ITS2 (ITS) and the 28S D1-D5 region of the Calocybe species were analyzed, and the results indicated that the three new species belonged to the genus Calocybe and differed from other species of Calocybe. The morphological similarities of the new species to other Calocybe species and the classification system within the genus Calocybe based on molecular data are also discussed. A key is provided for the Calocybe species as reported from China in order to facilitate future studies of the genus.

The marine horseshoe crab (Tachypleus tridentatus) has been considered as food and traditional medicine for many years. Kynurenic acid (KA) was isolated from horseshoe crab in this study for the first time in the world. A previous study in 2018 reported that intraperitoneal administration of KA prevented high-fat diet- (HFD-) induced body weight gain. Now, we investigated the effects of intragastric gavage of KA on HFD mice and found that KA (5 mg/kg/day) inhibited both the body weight gain and the increase of average daily energy intake. KA reduced serum triglyceride and increased serum high-density lipoprotein cholesterol. KA inhibited HFD-induced the increases of serum low-density lipoprotein cholesterol, coronary artery risk index, and atherosclerosis index. KA also suppressed HFD-induced the increase of the ratio of Firmicutes to Bacteroidetes (two dominant gut microbial phyla). KA partially reversed HFD-induced the changes in the composition of gut microbial genera. These overall effects of KA on HFD mice were similar to that of simvastatin (positive control). But the effects of 1.25 mg/kg/day KA on HFD-caused hyperlipidemia were similar to the effects of 5 mg/kg/day simvastatin. The pattern of relative abundance in 40 key genera of gut microbiota from KA group was closer to that from the normal group than that from the simvastatin group. In addition, our in vitro results showed the potential antioxidant activity of KA, which suggests that the improvement effects of KA on HFD mice may be partially associated with antioxidant activity of KA. Our findings demonstrate the potential role of KA as a functional food ingredient for the treatment of obesity and hyperlipidemia as well as the modulation of gut microbiota.

Foodborne pathogenic bacteria have become a worldwide threat to human health, and rapid and sensitive bacterial detection methods are urgently needed. In this study, a facile microfluidic chip was developed and combined with recombinase-aided amplification (RAA) for rapid and sensitive detection of Salmonella typhimurium using a non-contact eddy heater for dynamic lysis of bacterial cells and a 3D-printed fan-shaped active mixer for continuous-flow mixing. First, the bacterial sample was injected into the chip to flow through the spiral channel coiling around an iron rod under an alternating electromagnetic field, resulting in the dynamic lysis of bacterial cells by this non-contact eddy heater to release their nucleic acids. After cooling to ~75 °C, these nucleic acids were continuous-flow mixed with magnetic silica beads using the fan-shaped mixer and captured in the separation chamber using a magnet. Finally, the captured nucleic acids were eluted by the eluent from the beads to flow into the detection chamber, followed by RAA detection of nucleic acids to determine the bacterial amount. Under the optimal conditions, this microfluidic chip was able to quantitatively detect Salmonella typhimurium from 1.1 × 102 to 1.1 × 105 CFU/mL in 40 min with a detection limit of 89 CFU/mL and might be prospective to offer a simple, low-cost, fast and specific bacterial detection technique for ensuring food safety.