In vitro and in vivo fermentation models to study the function of dietary fiber in pig nutrition.

The importance of dietary fiber (DF) in animal diets is increasing with the advancement of nutritional research. DF is fermented by gut microbiota to produce metabolites, which are important in improving intestinal health. This review is a systematic review of DF in pig nutrition using in vitro and in vivo models. The fermentation characteristics of DF and the metabolic mechanisms of its metabolites were summarized in an in vitro model, and it was pointed out that SCFAs and gases are the important metabolites connecting DF, gut microbiota, and intestinal health, and they play a key role in intestinal health. At the same time, some information about host-microbe interactions could have been improved through traditional animal in vivo models, and the most direct feedback on nutrients was generated, confirming the beneficial effects of DF on sow reproductive performance, piglet intestinal health, and growing pork quality. Finally, the advantages and disadvantages of different fermentation models were compared. In future studies, it is necessary to flexibly combine in vivo and in vitro fermentation models to profoundly investigate the mechanism of DF on the organism in order to promote the development of precision nutrition tools and to provide a scientific basis for the in-depth and rational utilization of DF in animal husbandry. KEY POINTS: • The fermentation characteristics of dietary fiber in vitro models were reviewed. • Metabolic pathways of metabolites and their roles in the intestine were reviewed. • The role of dietary fiber in pigs at different stages was reviewed.

High fat diet-induced hyperlipidemia and tissue steatosis in rabbits through modulating ileal microbiota.

High-fat diet (HFD) and overnutrition are important starting factors that may alter intestinal microbiota, lipid metabolism, and systemic inflammation. However, there were few studies on how intestinal microbiota contributes to tissue steatosis and hyperlipidemia. Here, we investigated the effect of lipid metabolism disorder-induced inflammation via toll-like receptor 2 (TLR-2), toll-like receptor 4 (TLR-4), and nuclear factor-κB (NF-κB) pathways at the intestinal level in response to HFD. Twenty 80-day-old male New Zealand White rabbits were randomly divided into the normal diet group (NDG) and the high-fat diet group (HDG) for 80 days. Growth performance, blood biochemical parameters, lipid metabolism, inflammation, degree of tissue steatosis, and intestinal microbial composition were measured. HFD increased the relative abundance of Christensenellaceae_R_7_group, Marvinbryantia, Akkermansia etc., with a reduced relative abundance of Enterorhabdus and Lactobacillus. Moreover, HFD caused steatosis in the liver and abdominal fat and abnormal expression of some genes related to lipid metabolism and tight junction proteins. The TLR-2, TLR-4, NF-κB, TNF-α, and IL-6 were confirmed by overexpression with downregulation of IL-10. Serum biochemical indices (TG, TCHO, LDL-C, and HDL-C) were also increased, indicating evidence for the development of the hyperlipidemia model. Correlation analysis showed that this microbial dysbiosis was correlated with lipid metabolism and inflammation, which were associated with the intestinal tract's barrier function and hyperlipidemia. These results provide an insight into the relationship between HFD, the intestinal microbiota, intestinal barrier, tissue inflammation, lipid metabolism, and hyperlipidemia. KEY POINTS: • High-fat diet leads to ileal microbiota disorders • Ileal microbiota mediates local and systemic lipid metabolism disorders and inflammation • There is a specific link between ileal microbiota, histopathology, and hyperlipidemia.

Whole-plant corn silage improves rumen fermentation and growth performance of beef cattle by altering rumen microbiota.

In recent years, whole-plant corn silage has been widely used in China. Roughage is an important source of nutrition for ruminants and has an important effect on rumen microbiota, which plays an important role in animal growth performance and feed digestion. To better understand the effects of different silages on rumen microbiota, the effects of whole-plant corn silage or corn straw silage on growth performance, rumen fermentation products, and rumen microbiota of Simmental hybrid cattle were studied. Sixty healthy Simmental hybrid cattle were randomly divided into 2 groups with 6 replicates in each group and 5 cattle in each replicate. They were fed with whole-plant corn silage (WS) diet and corn straw silage (CS) diet respectively. Compared with corn straw silage, whole-plant corn silage significantly increased daily gain and decreased the feed intake-to-weight gain ratio (F/G) of beef cattle. Whole-plant corn silage also decreased the acetic acid in the rumen and the acetate-to-propionate ratio (A/P) compared with corn straw silage. On the genus level, the relative abundance of Prevotella_1 was significantly increased while the relative abundance of Succinivibrionaceae_UCG-002 was decreased in cattle fed whole-plant corn silage compared with those fed corn straw silage. Prevotella_1 was positively correlated with acetic acid and A/P. Succinivibrionaceae_UCG-002 was positively correlated with propionic acid and butyric acid, and negatively correlated with pH. Feeding whole-plant corn silage improved amino acid metabolism, nucleotide metabolism, and carbohydrate metabolism. Correlation analysis between rumen microbiota and metabolic pathways showed that Succinivibrionaceae_UCG-002 was negatively correlated with glycan biosynthesis and metabolism, metabolism of co-factors and vitamins, nucleotide metabolism, and translation while Prevotellaceae_UCG-003 was positively correlated with amino acid metabolism, carbohydrate metabolism, energy metabolism, genetic information processing, lipid metabolism, membrane transport, metabolism of cofactors and vitamins, nucleotide metabolism, replication and repair, and translation. Ruminococcus_2 was positively correlated with amino acid metabolism and carbohydrate metabolism. Feeding whole-plant corn silage can improve the growth performance and rumen fermentation of beef cattle by altering rumen microbiota and regulating the metabolism of amino acids, carbohydrates, and nucleotides. KEY POINTS: • Feeding whole-plant corn silage could decrease the F/G of beef cattle • Feeding whole-plant corn silage improves rumen fermentation in beef cattle • Growth performance of beef cattle is related to rumen microbiota and metabolism.

Ago HITS-CLIP expands microRNA-mRNA interactions in nucleus and cytoplasm of gastric cancer cells.

BACKGROUND: Intensive investigations have identified a collection of microRNAs (miRNAs) and their functional machineries in cytoplasm. However, a comprehensive view of miRNAs and mRNAs in cytoplasm and nucleus has not been explored. This study aims to reveal the mechanisms of miRNA-RNA interactions in nucleus and cytoplasm. METHODS: In this study, the miRNAs and their target mRNAs in the Argonaute2 (Ago2) complex of nucleus and cytoplasm of gastric cancer cells were characterized using high-throughput sequencing of RNAs isolated by crosslinking immunoprecipitation (HITS-CLIP). Then, the selected miRNAs were verified by Northern blot. The target mRNAs in the Argonaute2 (Ago2) complex of nucleus and cytoplasm of gastric cancer cells were analyzed through Gene ontology (GO) and Kyoto encyclopedia of genes and genomes (KEGG) analysis. RESULTS: The results revealed that there were 243 miRNAs and 265 miRNAs in the Ago2 complexes of nucleus and cytoplasm, respectively. The majority of mature miRNAs existed in cytoplasm. The analysis of miRNA targetome from the Ago2 complexes indicated that a lot of mRNAs with high expression level existed in nucleus. The target genes of miRNAs in the Ago2 complexes of nucleus and cytoplasm played important roles in cell proliferation, cell differentiation, innate immune response and tumorigenesis. CONCLUSIONS: microRNA-mRNA interactions occur in nucleus and cytoplasm of gastric cancer cells. Therefore, our study demonstrated that miRNA-mRNA interactions not only took place in cytoplasm but also in nucleus.

Signature microRNAs of nuclear Sm complex associated with breast cancer tumorigenesis.

It is well known that Sm proteins, small nuclear ribonucleoproteins, act as core spliceosomal factors in alternative splicing of mRNA precursors. MicroRNAs (miRNAs) can function in alternative splicing by targeting mRNAs of splicing factors. However, the direct interaction between miRNAs and proteins of splicing complex in nucleus has not been explored. In this study, the mature miRNAs in nuclear Sm complex of breast cancer cells and normal breast epithelial cells were characterized. Small RNA sequencing of immunoprecipitated nuclear Sm complex with the SmD1-specific antibody identified 123 and 170 mature miRNAs in nuclear Sm complex of normal breast cells and breast cancer cells, respectively. The results of Northern blot analysis confirmed the existence of mature miRNAs in Sm complex and electrophoretic mobility shift assay (EMSA) validated the binding of miRNAs with proteins of Sm complex. Among the identified miRNAs bound to the Sm complex in nucleus, 94 miRNAs were significantly upregulated, and 39 miRNAs significantly downregulated in breast cancer cells compared with normal breast cells, suggesting that miRNAs in nuclear Sm complex might be associated to tumorigenesis of breast cancer by regulating Sm complex during alternative splicing of mRNA precursors. Our study provided novel clues to reveal the regulatory mechanism of Sm complex in the assembly of spliceosome and contributed novel aspects of miRNAs to tumorigenesis of breast cancer.

Two White Spot Syndrome Virus MicroRNAs Target the Dorsal Gene To Promote Virus Infection in Marsupenaeus japonicus Shrimp.

In eukaryotes, microRNAs (miRNAs) serve as regulators of many biological processes, including virus infection. An miRNA can generally target diverse genes during virus-host interactions. However, the regulation of gene expression by multiple miRNAs has not yet been extensively explored during virus infection. This study found that the Spaztle (Spz)-Toll-Dorsal-antilipopolysaccharide factor (ALF) signaling pathway plays a very important role in antiviral immunity against invasion of white spot syndrome virus (WSSV) in shrimp (Marsupenaeus japonicus). Dorsal, the central gene in the Toll pathway, was targeted by two viral miRNAs (WSSV-miR-N13 and WSSV-miR-N23) during WSSV infection. The regulation of Dorsal expression by viral miRNAs suppressed the Spz-Toll-Dorsal-ALF signaling pathway in shrimp in vivo, leading to virus infection. Our study contributes novel insights into the viral miRNA-mediated Toll signaling pathway during the virus-host interaction.IMPORTANCE An miRNA can target diverse genes during virus-host interactions. However, the regulation of gene expression by multiple miRNAs during virus infection has not yet been extensively explored. The results of this study indicated that the shrimp Dorsal gene, the central gene in the Toll pathway, was targeted by two viral miRNAs during infection with white spot syndrome virus. Regulation of Dorsal expression by viral miRNAs suppressed the Spz-Toll-Dorsal-ALF signaling pathway in shrimp in vivo, leading to virus infection. Our study provides new insight into the viral miRNA-mediated Toll signaling pathway in virus-host interactions.

Involvement of viral microRNA in the regulation of antiviral apoptosis in shrimp.

Viruses, in particular DNA viruses, generate microRNAs (miRNAs) to control the expression of host and viral genes. Due to their essential roles in virus-host interactions, viral miRNAs have attracted extensive investigations in recent years. To date, however, most studies on viral miRNAs have been conducted in cell lines. In this study, the viral miRNAs from white spot syndrome virus (WSSV) were characterized in shrimp in vivo. On the basis of our previous study and small RNA sequencing in this study, a total of 89 putative WSSV miRNAs were identified. As revealed by miRNA microarray analysis and Northern blotting, the expression of viral miRNAs was tissue specific in vivo. The results indicated that the viral miRNA WSSV-miR-N24 could target the shrimp caspase 8 gene, and this miRNA further repressed the apoptosis of shrimp hemocytes in vivo. As a result, the number of WSSV copies in shrimp in vivo was significantly increased compared with the control level (WSSV only). Therefore, our study presents the first report on the in vivo molecular events of viral miRNA in antiviral apoptosis.

Supplementing Ryegrass Ameliorates Commercial Diet-Induced Gut Microbial Dysbiosis-Associated Spleen Dysfunctions by Gut-Microbiota-Spleen Axis.

The type and composition of food strongly affect the variation and enrichment of the gut microbiota. The gut-microbiota-spleen axis has been developed, incorporating the spleen's function and maturation. However, how short-chain fatty-acid-producing gut microbiota can be considered to recover spleen function, particularly in spleens damaged by changed gut microbiota, is unknown in geese. Therefore, the gut microbial composition of the caecal chyme of geese was assessed by 16S rRNA microbial genes, and a Tax4Fun analysis identified the enrichment of KEGG orthologues involved in lipopolysaccharide production. The concentrations of LPS, reactive oxygen species, antioxidant/oxidant enzymes, and immunoglobulins were measured from serum samples and spleen tissues using ELISA kits. Quantitative reverse transcription PCR was employed to detect the Kelch-like-ECH-associated protein 1-Nuclear factor erythroid 2-related factor 2 (Keap1-Nrf2), B cell and T cell targeting markers, and anti-inflammatory/inflammatory cytokines from the spleen tissues of geese. The SCFAs were determined from the caecal chyme of geese by using gas chromatography. In this study, ryegrass-enriched gut microbiota such as Eggerthellaceae, Oscillospiraceae, Rikenellaceae, and Lachnospiraceae attenuated commercial diet-induced gut microbial alterations and spleen dysfunctions in geese. Ryegrass significantly improved the SCFAs (acetic, butyric, propionic, isovaleric, and valeric acids), AMPK pathway-activated Nrf2 redox signaling cascades, B cells (B220, CD19, and IgD), and T cells (CD3, CD4, CD8, and IL-2, with an exception of IL-17 and TGF-ß) to activate anti-inflammatory cytokines (IL-4 and IL-10) and immunoglobulins (IgA, IgG, and IgM) in geese. In conclusion, ryegrass-improved reprogramming of the gut microbiota restored the spleen functions by attenuating LPS-induced oxidative stress and systemic inflammation through the gut-microbiota-spleen axis in geese.

Fecal microbiota transplantation alleviates intestinal inflammatory diarrhea caused by oxidative stress and pyroptosis via reducing gut microbiota-derived lipopolysaccharides.

Infancy is a critical period in the maturation of the gut microbiota and a phase of susceptibility to gut microbiota dysbiosis. Early disturbances in the gut microbiota can have long-lasting effects on host physiology, including intestinal injury and diarrhea. Fecal microbiota transplantation (FMT) can remodel gut microbiota and may be an effective way to treat infant diarrhea. However, limited research has been conducted on the mechanisms of infant diarrhea and the regulation of gut microbiota balance through FMT, primarily due to ethical challenges in testing on human infants. Our study demonstrated that elevated Lipopolysaccharides (LPS) levels in piglets with diarrhea were associated with colon microbiota dysbiosis induced by early weaning. Additionally, LPS upregulated NLRP3 levels by activating TLR4 and inducing ROS production, resulting in pyroptosis, disruption of the intestinal barrier, bacterial translocation, and subsequent inflammation, ultimately leading to diarrhea in piglets. Through microbiota regulation, FMT modulated ß-PBD-2 secretion in the colon by increasing butyric acid levels. This modulation alleviated gut microbiota dysbiosis, reduced LPS levels, attenuated oxidative stress and pyroptosis, inhibited the inflammatory response, maintained the integrity of the intestinal barrier, and ultimately reduced diarrhea in piglets caused by colitis. These findings present a novel perspective on the pathogenesis, pathophysiology, prevention, and treatment of diarrhea diseases, underscoring the significance of the interaction between FMT and the gut microbiota as a critical strategy for treating diarrhea and intestinal diseases in infants and farm animals.

The Mechanism of the Gut-Brain Axis in Regulating Food Intake.

With the increasing prevalence of energy metabolism disorders such as diabetes, cardiovascular disease, obesity, and anorexia, the regulation of feeding has become the focus of global attention. The gastrointestinal tract is not only the site of food digestion and absorption but also contains a variety of appetite-regulating signals such as gut-brain peptides, short-chain fatty acids (SCFAs), bile acids (BAs), bacterial proteins, and cellular components produced by gut microbes. While the central nervous system (CNS), as the core of appetite regulation, can receive and integrate these appetite signals and send instructions to downstream effector organs to promote or inhibit the body's feeding behaviour. This review will focus on the gut-brain axis mechanism of feeding behaviour, discussing how the peripheral appetite signal is sensed by the CNS via the gut-brain axis and the role of the central "first order neural nuclei" in the process of appetite regulation. Here, elucidation of the gut-brain axis mechanism of feeding regulation may provide new strategies for future production practises and the treatment of diseases such as anorexia and obesity.

Alfalfa hay substitution for wheat straw improves beef quality via rumen microflora alteration.

The use of high-quality roughage to improve beef quality has become an important issue in China, as the country has become the world's largest beef consumer. This study aimed to evaluate the effects of different forage qualities (wheat straw vs alfalfa hay) on Simmental crossbreed cattle's meat quality, rumen fermentation and microbiota. AHG (Alfalfa hay group) improved the ADFI (Average daily feed intake) and ADG (Average daily gain) of the beef cattle, meat-to-bone ratio and EE (Ether extract). The C18:3n3 and C20:3n3 composition of LD in AHG was significantly higher than WSG. An increase in the relative abundance of Firmicutes and a decrease in Bacteroidetes was observed. AHG resulted in higher relative abundance of Saccharomonospora, Streptomyces. A negative correlation between Treponema and muscle PUFA was noticed. Prevotella was negatively correlated with starch and sucrose metabolism. In conclusion, current study demonstrates that feeding alfalfa hay can raise meat quality by altering the rumen microbiota, providing valuable information for the application of alfalfa hay in beef cattle breeding.

Artificial Pasture Grazing System Attenuates Lipopolysaccharide-Induced Gut Barrier Dysfunction, Liver Inflammation, and Metabolic Syndrome by Activating ALP-Dependent Keap1-Nrf2 Pathway.

INTRODUCTION: Geese can naturally obtain dietary fiber from pasture, which has anti-inflammatory and antioxidant properties. This study aimed to investigate the inhibitory impacts of pasture on ameliorating LPS-ROS-induced gut barrier dysfunction and liver inflammation in geese. Materials and methods. The lipopolysaccharides (LPS), alkaline phosphatase (ALP), reactive oxygen species (ROS), tight junction proteins, antioxidant enzymes, immunoglobulins, and metabolic syndrome were determined using ELISA kits. The Kelch-like-ECH-associated protein 1-Nuclear factor erythroid 2-related factor 2 (Keap1-Nrf2) and inflammatory cytokines were determined using the quantitative reverse transcription PCR (RT-qPCR) method. The intestinal morphology was examined using the Hematoxylin and Eosin (H&E) staining method in ileal tissues. Results. Pasture significantly influences nutrient absorption (p < 0.001) by ameliorating LPS and ROS-facilitated ileal permeability (p < 0.05) and systemic inflammation (p < 0.01). Herein, the gut permeability was paralleled by liver inflammation, which was significantly mimicked by ALP-dependent Nrf2 (p < 0.0001) and antioxidant enzyme activation (p < 0.05). Indeed, the correlation analysis of host markers signifies the importance of pasture in augmenting geese's health and production by averting gut and liver inflammation. Conclusions. Our results provide new insight into the mechanism of the pasture-induced ALP-dependent Nrf2 signaling pathway in limiting systemic inflammation in geese.

Polysaccharide from Smilax glabra Roxb Mitigates Intestinal Mucosal Damage by Therapeutically Restoring the Interactions between Gut Microbiota and Innate Immune Functions.

Smilax glabra Roxb (S. glabra) is a conventional Chinese medicine that is mainly used for the reliability of inflammation. However, bioactive polysaccharides from S. glabra (SGPs) have not been thoroughly investigated. Here, we demonstrate for the first time that SGPs preserve the integrity of the gut epithelial layer and protect against intestinal mucosal injury induced by dextran sulfate sodium. Mechanistically, SGPs mitigated colonic mucosal injury by restoring the association between the gut flora and innate immune functions. In particular, SGPs increased the number of goblet cells, reduced the proportion of apoptotic cells, improved the differentiation of gut tight junction proteins, and enhanced mucin production in the gut epithelial layer. Moreover, SGPs endorsed the propagation of probiotic bacteria, including Lachnospiraceae bacterium, which strongly correlated with decreased pro-inflammatory cytokines via the blocking of the TLR-4 NF-κB and MyD88 pathways. Overall, our study establishes a novel use of SGPs for the treatment of inflammatory bowel disease (IBD)-associated mucosal injury and provides a basis for understanding the therapeutic effects of natural polysaccharides from the perspective of symbiotic associations between host innate immune mechanisms and the gut microbiome.

Effects of Silage Diet on Meat Quality through Shaping Gut Microbiota in Finishing Pigs.

With increasing demand for high-quality pork, development of green and healthy feed for finishing pigs is urgently needed. In this study, the effects and mechanisms of mulberry and paper mulberry silages on growth performance, meat quality, and intestinal health of finishing pigs were explored. Intestinal microbiota were profiled, and microbially produced short-chain fatty acids (SCFAs) were measured. The average daily gain (ADG) and feed conversion rate (FCR) with mulberry and paper mulberry silages were not significantly different from those of the control. Meat quality as measured by pork marbling and fatty acids in the longissimus dorsi was better with mulberry silage. The highest concentration of SCFAs was also with mulberry silage. According to 16S rRNA sequencing, Clostridium_sensu_stricto_1, Terrisporobacter, and Lachnospiraceae, which are important in SCFA production, were biomarkers of mulberry silage. PICRUSt functional analysis of intestinal microbes indicated that galactose metabolism, starch and sucrose metabolism, and carbohydrate digestion and absorption decreased significantly in silage treatments but increased in the control. Correlations between intestinal microbes and SCFAs and fatty acids indicated Clostridium_sensu_stricto_1, Terrisporobacter, and Lachnospiraceae were closely associated with SCFA and fatty acid contents. The results indicated that mulberry silage could increase SCFA content through shaping intestinal microbes to affect the deposition of fatty acids, which laid a solid theoretical foundation for improving pork quality. IMPORTANCE To avoid competition between people and animals for food, it is essential to develop nontraditional feeds. In this study, the effects of the silages of the unconventional feed resources mulberry and paper mulberry on meat quality of finishing pigs were examined. With mulberry silage in the diet, meat quality improved as indicated by meat color, marbling score, and beneficial fatty acids in the longissimus dorsi muscle. Pigs fed mulberry silage had the highest concentrations of short-chain fatty acids (SCFAs), and 16S rRNA sequencing identified Clostridium_sensu_stricto_1, Terrisporobacter, and Lachnospiraceae as biomarkers, which are important in SCFA production. Functions of intestinal microbes in the two silage groups primarily involved amino acid metabolism and SCFA production. Correlations between intestinal microbes and SCFAs and fatty acids indicated that Clostridium_sensu_stricto-1, Terrisporobacter, and Lachnospiraceae were closely associated with SCFA contents in the intestine and fatty acids in the longissimus dorsi.

Alfalfa Silage Diet Improves Meat Quality by Remodeling the Intestinal Microbes of Fattening Pigs.

Because the demand for pork is increasing, it is crucial to devise efficient and green methods to improve the quality and quantity of meat. This study investigated the improvement in pork quality after the inclusion of alfalfa meal or alfalfa silage in pig diet. Our results indicated that alfalfa silage improved meat quality more effectively in terms of water-holding capacity, drip loss, and marbling score. Besides, an alfalfa silage diet can affect the level of fatty acids and amino acids in pork. Further, alfalfa silage was found to improve meat quality by remodeling intestinal microbiota and altering the level of SCFAs, providing a viable option for improving meat quality through forage.

Effects of Diets Combining Peanut Vine and Whole-Plant Corn Silage on Growth Performance, Meat Quality and Rumen Microbiota of Simmental Crossbred Cattle.

Peanut vine is a typical peanut by-product and can be used as a quality roughage resource. Whole-plant corn silage is a commonly used roughage. However, few studies have investigated the effects of diets combining peanut vine and whole-plant corn silage on growth performance, antioxidant capacity, meat quality, rumen fermentation and microbiota of beef cattle. To investigate these effects, eighty Simmental crossbred cattle (body weight, 451.27 ± 10.38 kg) approximately 14 months old were randomly divided into four treatments for a 90-day feeding experiment. A one-way design method was used in this experiment. According to the roughage composition, the cattle were divided into a control treatment of 45% wheat straw and 55% whole-plant corn silage (WG), and three treatments of 25% peanut vine and 75% whole-plant corn silage (LPG), 45% peanut vine and 55% whole-plant corn silage (MPG), and 65% peanut vine and 35% whole-plant corn silage (HPG), and the concentrate was the same for all four treatment diets. The results showed that compared to the WG group, the MPG group experienced an increase in their average daily feed intake of 14%, an average daily gain of 32%, and an increase in SOD activity in the spleen of 33%; in the meat, dry matter content increased by 11%, crude protein by 9%, and ether extract content by 40%; in the rumen, the NH3-N content was reduced by 36%, the relative abundance of Firmicutes increased, and the relative abundance of Bacteroidetes decreased (p < 0.05). These results showed the composition of 45% peanut vine and 55% whole-plant corn silage in the roughage improved growth performance, antioxidant capacity, meat quality, rumen fermentation, and microbiota of beef cattle.

Suppression of RNA editing by miR-17 inhibits the stemness of melanoma stem cells.

More and more evidence suggests that microRNA (miRNA) and RNA editing play key roles in the development and progression of tumor. However, the influence of miRNA-mediated RNA editing on tumor stem cells remains unclear. In this study, the results demonstrated that miR-17, which was downregulated in melanoma stem cells, acted as a tumor inhibitor by suppressing the stemness of melanoma stem cells and promoting cell differentiation. MiR-17 targeted ADAR2 (adenosine deaminase acting on RNA 2), a gene encoding an editing enzyme required for the maintenance of melanoma stem cell stemness. In melanoma stem cells, ADAR2 was responsible for DOCK2 mRNA editing, which was able to increase the stability of DOCK2 mRNA. The in vitro and in vivo data demonstrated that DOCK2 mRNA editing upregulated the expressions of stemness and anti-apoptotic genes by activating Rac1 and then phosphorylating Akt and NF-κB, thus leading to oncogenesis of melanoma stem cells. Our findings contribute new perspectives to miRNA-regulated RNA editing in tumor progression.

Effects of Different Roughage Diets on Fattening Performance, Meat Quality, Fatty Acid Composition, and Rumen Microbe in Steers.

This study aimed to evaluate different roughages on fatting performance, muscle fatty acids, rumen fermentation and rumen microbes of steers. Seventy-five Simmental crossbred steers were randomly divided into wheat straw group (WG), peanut vine group (PG) and alfalfa hay group (AG), with 5 replicates of 5 steers each. The results showed a highest average daily gain and lowest feed/gain ratio in AG group (P = 0.001). Steers fed alfalfa hay had the highest muscle marbling score and n-3 polyunsaturated fatty acid (PUFA), and also the rumen NH3-N and microbial protein (MCP) concentration among the three groups (P < 0.05). Correlation analysis showed that ruminal NH3-N and MCP were negatively correlated with muscle saturated fatty acid (SFA), while ruminal MCP was positively correlated with muscle PUFA and n-3 PUFA (P < 0.05). 16S rRNA analysis indicated that fed alfalfa hay decreased the abundance of Ruminococcaceae_UCG-001(P = 0.005). More importantly, muscle SFA deposition were positively correlated to the abundance of Ruminococcaceae_UCG-001 (P < 0.05), while the muscle PUFA and n-3 PUFA deposition were negatively correlated to it (P < 0.01). Therefore, alfalfa hay provides a better fattening effect on steers. Alfalfa rich in n-3 PUFA would reduce the abundance of Ruminococcaceae_UCG-001 involved in hydrogenation, increase the rumen protective effect of C18:3 n-3, which is beneficial to the deposition of muscle n-3 PUFA and PUFA.

Gut Microbiota Modulate Rabbit Meat Quality in Response to Dietary Fiber.

Antibiotics are widely used in gastrointestinal diseases in meat rabbit breeding, which causes safety problems for meat products. Dietary fiber can regulate the gut microbiota of meat rabbits, but the mechanism of improving meat quality is largely unknown. The objective of this study was to evaluate the effects of adding different fiber sources to rabbit diets on the growth performance, gut microbiota composition, and muscle metabolite composition of meat rabbits. A total of 18 New Zealand white rabbits of similar weight (40 ± 1 day old) were randomly assigned to beet pulp treatment (BP), alfalfa meal treatment (AM), and peanut vine treatment (PV). There were 6 repeats in each treatment and all were raised in a single cage. The predictive period was 7 days and the experimental period was 40 days. The results revealed that AM and PV supplementation increased growth performance, slaughter performance, and intestinal development of meat rabbits compared with the BP treatment, and especially the effect of AM treatment was better. The content of butyric acid was increased in PV and AM treatments compared with the BP treatment. The expression of mitochondrial biosynthesis genes of liver, cecum, and muscle showed that AM treatment increased gene expression of CPT1b compared to the BP treatment. In addition, AM and PV treatments significantly increased the microbial diversity and richness compared with BP treatment, and their bacterial community composition was similar, and there were some differences between AM and PV treatments and BP treatment. Metabonomics analysis of muscle showed that AM treatment significantly increased amino acid and fatty acid metabolites compared with BP treatment, which were mainly concentrated in energy metabolism, amino acid metabolism, and fatty acid regulation pathways. Furthermore, through correlation analysis, it was found that there was a significant correlation between rumenococci in the cecum and amino acid metabolites in the muscle. Overall, these findings indicate that AM may affect the body's health by changing its gut microbiota, and then improving meat quality, and the intestinal-muscle axis provides a theoretical basis.