RNA-binding protein complex AMG-1/SLRP-1 mediates germline development and spermatogenesis by maintaining mitochondrial homeostasis in Caenorhabditis elegans.

The mechanisms of RNA-binding proteins (RBPs)-mediated post-transcriptional regulation of pre-existing mRNAs, which is essential for spermatogenesis, remain poorly understood. In this study, we identify that a germline-specific mitochondrial RBP AMG-1(abnormal mitochondria in germline 1), a homolog of mammalian leucine-rich PPR motif-containing protein (LRPPRC), is required for spermatogenesis in Caenorhabditis elegans. The amg-1 mutation hinders germline development without affecting somatic development and leads to the aberrant mitochondrial morphology and structure associated with mitochondrial dysfunctions specifically in the germline. We demonstrate that AMG-1 is most frequently bound to mtDNA-encoded 12S and 16S ribosomal RNA, the essential components of mitochondrial ribosomes, and that 12S rRNA expression mediated by AMG-1 is crucial for germline mitochondrial protein homeostasis. Furthermore, steroid receptor RNA activator (SRA) stem loop interacting RNA binding protein (SLRP-1), a homolog of mammalian SRA stem loop interacting RNA binding protein (SLIRP) in C. elegans, interacts with AMG-1 genetically to regulate germline development and reproductive success in C. elegans. Overall, these findings reveal the novel function of mtRBP, specifically in regulating germline development.

Effects of cold storage time on the quality and active probiotics of yogurt fermented by Bifidobacterium lactis and commercial bacteria Danisco.

In this study, the commercial bacteria Danisco and Bifidobacterium lactis were used to ferment soy yogurt, and then the quality of yogurt and the number of active probiotics in yogurt during storage were investigated. The results showed that the total number of viable bacteria in soy yogurt increased first and then decreased, but all of them met the standard for the number of viable bacteria in probiotic foods. The content of protein, lipid, and total sugar in soy yogurt decreased gradually with the extension of storage time. The texture, water holding capacity, and rheological properties of soy yogurt were improved within 0-10 days, and there was no significant change after 15 days. However, brightness and whiteness of yogurt were significantly reduced. Based on realizing the reuse of soy whey, this study provided a theoretical basis for the research of the shelf life of soy yogurt. PRACTICAL APPLICATION: This study developed a soy yogurt with good quality and provided a theoretical basis for the study of the shelf life of soy yogurt. In addition, some technical support was provided for the reuse of soy whey.

Defatted hempseed meal altered the metabolic profile of fermented yogurt and enhanced the ability to alleviate constipation in rats.

BACKGROUND: Hempseeds (Cannabis sativa L.) are rich in easily digestible proteins, fats, polyunsaturated fatty acids, and insoluble fiber and are of high nutritional value. Probiotics have been found to relieve constipation, which solves a health problem that constantly troubles a lot of people. Therefore, the changes in the metabolites of fermented yogurt with or without 10% defatted hempseed meal (10% SHY or 0% SHY respectively) were studied and their laxative effects were examined through animal experiments. RESULTS: Amino acids and peptides, terpene glycosides, carbohydrates, lineolic acids, and fatty acids were found to be the major contributors to the discrimination of the metabolic profile between 0% SHY and 10% SHY. The differentially accumulated metabolites may lead to the discrepancy in the yogurt's functionality. Animal experiments showed that the 10% SHY treatment prevented constipation by increasing feces number, fecal water content, and small intestinal transit rate and reducing inflammatory injury in loperamide-induced constipated rats. Further analysis of the gut microbiota revealed that 10% SHY gavage increased the relative abundances of the Lactobacillus, Allobaculum, Turicibacter, Oscillibacter, Ruminococcus, and Phascolarctobacterium genera in the constipated rats, whereas Akkermansia, Clostridium_XIVa, Bacteroides, Staphylococcus, and Clostridium_IV were decreased. The combination of defatted hempseed meal and probiotics was found to be effective in relieving constipation, probably due to the enriched amino acids and peptides, such as Thr-Leu and lysinoalanine through correlation analysis. CONCLUSION: Our findings indicated that defatted hempseed meal in yogurt altered the metabolic profile and effectively alleviated constipation in rats, which is a promising therapeutic candidate for constipation. © 2023 Society of Chemical Industry.

Homogenized soybean hull suspension as an emulsifier for oil/water emulsions: Synergistic effect of the insoluble fiber and soluble polysaccharide.

In this study, the functional properties of the soybean hull soluble fractions and insoluble fiber in stabilizing oil-in-water emulsions were investigated by changing the soluble fraction (SF) content in the soybean hull suspensions. High-pressure homogenization (HPH) caused the release of soluble materials (Polysaccharides and proteins) and the deagglomeration of insoluble fibers (IF) from soybean hulls. The apparent viscosity of the soybean hull fiber suspension increased as the SF content of the suspension increased; The absolute value of ζ-potential increased from 18 to 28 mV. In addition, the IF individually stabilized emulsion had the largest emulsion particle size (32.10 µm), but decreased as the SF content in the suspension increased to 10.53 µm. The microstructure of the emulsions showed that surface-active SF adsorbed at the oil-water interface formed an interfacial film, and microfibrils in IF formed a three-dimensional network in the aqueous phase, which synergistically stabilized the oil-in-water emulsion. The findings of this study are important for understanding emulsion systems stabilized by agricultural by-products.

Structure/function relationships of bean polysaccharides: A review.

Beans are a rich source of high quality protein and oil, and have attracted increasing interest from both nutrition researchers and health-conscious consumers. This review aims to provide a foundation for the future research and development of bean polysaccharides, by summarizing the sources, structure, and functions of bioactive bean polysaccharides. Structure/function relationships are described, for biological activities, such as immunological, antioxidant and anti-diabetes. This will provide useful guidance for further optimization of polysaccharide structure and the development of bean polysaccharides as a novel functional material.

Effects of different combinations of probiotics on rheology, microstructure, and moisture distribution of soy materials-based yogurt.

The effects of different probiotics on the texture, rheological properties, microstructure, and water distribution of yogurt fermented with soy powder, soy isolate protein powder, soy umbilical powder, and soy whey as the main raw materials were studied. The soy materials-based yogurt fermented by Danisco mixed probiotic reached the end of fermentation after 4 h, which significantly shortened the fermentation time compared with other probiotic combinations. The fermentation with Danisco mixed probiotic and Kefir mixed probiotic respectively resulted in good texture and a denser and more homogeneous microstructure, which was consistent with the sensory evaluation results. Both fermentations had a high water holding capacity of 90.92% and 78.30%, respectively, in agreement with the results of moisture distribution tests. However, the elastic and viscous behaviors were weaker at certain shear frequency. This study achieved a high value-added utilization of soy whey and the development of a new soy materials-based yogurt that met the consumption needs of people with lactose intolerance and high cholesterol. PRACTICAL APPLICATION: In this study, high value-added utilization of soy whey was realized, which solved the problems of resource waste and environmental pollution. Meanwhile, the research and development of soy materials-based yogurt provided another nutritional and healthy consumption demand for lactose intolerant people.

Membrane contact site-dependent cholesterol transport regulates Na+/K+-ATPase polarization and spermiogenesis in Caenorhabditis elegans.

Spermiogenesis in nematodes is a process whereby round and quiescent spermatids differentiate into asymmetric and crawling spermatozoa. The molecular mechanism underlying this symmetry breaking remains uncharacterized. In this study, we revealed that sperm-specific Na+/K+-ATPase (NKA) is evenly distributed on the plasma membrane (PM) of Caenorhabditis elegans spermatids but is translocated to and subsequently enters the invaginated membrane of the spermatozoa cell body during sperm activation. The polarization of NKA depends on the transport of cholesterol from the PM to membranous organelles (MOs) via membrane contact sites (MCSs). The inositol 5-phosphatase CIL-1 and the MO-localized PI4P phosphatase SAC-1 may mediate PI4P metabolism to drive cholesterol countertransport via sterol/lipid transport proteins through MCSs. Furthermore, the NKA function is required for C. elegans sperm motility and reproductive success. Our data imply that the lipid dynamics mediated by MCSs might play crucial roles in the establishment of cell polarity. eGraphical abstract.

The zinc transporter ZIPT-7.1 regulates sperm activation in nematodes.

Sperm activation is a fascinating example of cell differentiation, in which immotile spermatids undergo a rapid and dramatic transition to become mature, motile sperm. Because the sperm nucleus is transcriptionally silent, this transition does not involve transcriptional changes. Although Caenorhabditis elegans is a leading model for studies of sperm activation, the mechanisms by which signaling pathways induce this transformation remain poorly characterized. Here we show that a conserved transmembrane zinc transporter, ZIPT-7.1, regulates the induction of sperm activation in Caenorhabditis nematodes. The zipt-7.1 mutant hermaphrodites cannot self-fertilize, and males reproduce poorly, because mutant spermatids are defective in responding to activating signals. The zipt-7.1 gene is expressed in the germ line and functions in germ cells to promote sperm activation. When expressed in mammalian cells, ZIPT-7.1 mediates zinc transport with high specificity and is predominantly located on internal membranes. Finally, genetic epistasis places zipt-7.1 at the end of the spe-8 sperm activation pathway, and ZIPT-7.1 binds SPE-4, a presenilin that regulates sperm activation. Based on these results, we propose a new model for sperm activation. In spermatids, inactive ZIPT-7.1 is localized to the membranous organelles, which contain higher levels of zinc than the cytoplasm. When sperm activation is triggered, ZIPT-7.1 activity increases, releasing zinc from internal stores. The resulting increase in cytoplasmic zinc promotes the phenotypic changes characteristic of activation. Thus, zinc signaling is a key step in the signal transduction process that mediates sperm activation, and we have identified a zinc transporter that is central to this activation process.

The regulatory functions of piRNA/PIWI in spermatogenesis.

A class of 24-32 nt PIWI-binding small noncoding RNAs (sncRNAs) termed as PIWI-interacting RNAs (piRNAs) have been identified in animal germline. Recent studies suggest that piRNA/PIWI pathway plays a critical role in both silencing of transposons and posttranscriptional regulation of mRNAs in animal germline. A study from Dr. Mofang Liu's lab in Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, reveals the physiological and pathological importance of PIWI metabolism (mouse PIWI as known as MIWI; human PIWI as HIWI) in mammalian spermatogenesis. Here, we summarize our current understanding of the piRNA/PIWI pathway in mammals (focusing on mouse and human), which is emerging as a fundamental component of spermatogenesis that ensures male fertility and genome integrity.