No abstract

Isolating and maintaining the appropriate stem cell for large scale cell culture is essential in tissue engineering or food production. For bovine satellite cells an optimized isolation and purification protocol is lacking and there is also no detailed understanding on the factors that maintain stemness of these cells. Here, we set up a fluorescence-activated cell sorting strategy to enrich bovine satellite cells. We found that p38-MAPK signalling is activated and PAX7 expression is gradually lost during satellite cell proliferation. The p38 inhibitor (SB203580) treatment maintained PAX7 expression but inhibited the fusion of satellite cells in a concentration-dependent way in short-term incubation. The mechanism of p38 inhibition was confirmed by inhibiting canonical p38 signalling, i.e. HSP27. Long-term culture with an appropriate concentration of p38i enhanced the proliferation and PAX7 expression, while the differentiation capacity recovered and was enhanced compared to vehicle control. These studies indicate that bovine satellite cells maintenance depends on cell purity and p38 MAPK signalling. Inhibition of p38 MAPK signaling is a promising strategy to facilitate large scale cell expansion of primary cells for tissue engineering and cultured meat purposes.

High-salt diet has been considered to cause health problems, but it is still less known how high-salt diet affects gut microbiota, protein digestion, and passage in the digestive tract. In this study, C57BL/6J mice were fed low- or high-salt diets (0.25 vs. 3.15% NaCl) for 8 weeks, and then gut contents and feces were collected. Fecal microbiota was identified by sequencing the V4 region of 16S ribosomal RNA gene. Proteins and digested products of duodenal, jejunal, cecal, and colonic contents were identified by LC-MS-MS. The results indicated that the high-salt diet increased Firmicutes/Bacteroidetes ratio, the abundances of genera Lachnospiraceae and Ruminococcus (P < 0.05), but decreased the abundance of Lactobacillus (P < 0.05). LC-MS-MS revealed a dynamic change of proteins from the diet, host, and gut microbiota alongside the digestive tract. For dietary proteins, high-salt diet seemed not influence its protein digestion and absorption. For host proteins, 20 proteins of lower abundance were identified in the high-salt diet group in duodenal contents, which were involved in digestive enzymes and pancreatic secretion. However, no significant differentially expressed proteins were detected in jejunal, cecal, and colonic contents. For bacterial proteins, proteins secreted by gut microbiota were involved in energy metabolism, sodium transport, and protein folding. Five proteins (cytidylate kinase, trigger factor, 6-phosphogluconate dehydrogenase, transporter, and undecaprenyl-diphosphatase) had a higher abundance in the high-salt diet group than those in the low-salt group, while two proteins (acetylglutamate kinase and PBSX phage manganese-containing catalase) were over-expressed in the low-salt diet group than in the high-salt group. Consequently, high-salt diet may alter the composition of gut microbiota and has a certain impact on protein digestion.

Reactive oxygen species (ROS) and ROS-dependent (redox regulation) signaling pathways and transcriptional activities are thought to be critical in stem cell self-renewal and differentiation during growth and organogenesis. Aberrant ROS burst and dysregulation of those ROS-dependent cellular processes are strongly associated with human diseases including many cancers. ROS levels are elevated in cancer cells partially due to their higher metabolism rate. In the past 15 years, the concept of cancer stem cells (CSCs) has been gaining ground as the subpopulation of cancer cells with stem cell-like properties and characteristics have been identified in various cancers. CSCs possess low levels of ROS and are responsible for cancer recurrence after chemotherapy or radiotherapy. Unfortunately, how CSCs control ROS production and scavenging and how ROS-dependent signaling pathways contribute to CSCs function remain poorly understood. This review focuses on the role of redox balance, especially in ROS-dependent cellular processes in cancer stem cells (CSCs). We updated recent advances in our understanding of ROS generation and elimination in CSCs and their effects on CSC self-renewal and differentiation through modulating signaling pathways and transcriptional activities. The review concludes that targeting CSCs by manipulating ROS metabolism/dependent pathways may be an effective approach for improving cancer treatment.

No abstract

Low-frequency and high-power ultrasound (40 kHz, 1,500 W) was tested for its effects on the characteristics of intramuscular heat-insoluble collagen and meat quality and textural properties of beef semitendinosus muscle. Meat steaks (2.5×5.0×5.0 cm, 100± 5 g) were sonicated for 10, 20, 30, 40, 50, and 60 min, respectively. Characteristics changes of collagen and meat quality and texture were estimated. The results indicated that ultrasound treatment had no significant (P>0.05) effects on L* (lightness) and a* (redness) values but decreased b* (yellowness) value significantly when sonicated for 30 min (minimum 6.98). Ultrasound treatment significantly (P<0.01) reduced the muscle fiber diameter and filtering residues but had no significant effects on the content of heat-insoluble collagen. Significant differences (P <0.05) in β-galactosidase and β-glucuronidase activity were found between ultrasound treated for 10 min (reached the minimum were 5.2×10 −3 and 1.6×10 −3 umol ml −1 min −1 , respectively) and control samples. Thermal characteristics analysis of collagen suggested that ultrasound treatment weaken the average stability of collagen. After ultrasound treatment, collagenous fibers were disordered and staggered significantly; fiber arrangement became loose; and the denaturing, granulation, and aggregation of collagen fiber appeared in the extracellular space. Those changes on collagen characteristics had significant effects on meat textural properties. The results suggested that low-frequency and high-power sonication had a significant effect on collagen characters and meat textural properties.

No abstract

Diet has been shown to have a critical influence on gut bacteria and host health, and high levels of red meat in diet have been shown to increase colonic DNA damage and thus be harmful to gut health. However, previous studies focused more on the effects of meat than of meat proteins. In order to investigate whether intake of meat proteins affects the composition and metabolic activities of gut microbiota, feces were collected from growing rats that were fed with either meat proteins (from beef, pork or fish) or non-meat proteins (casein or soy) for 14 days. The resulting composition of gut microbiota was profiled by sequencing the V4-V5 region of the 16S ribosomal RNA genes and the short chain fatty acids (SCFAs) were analyzed using gas chromatography. The composition of gut microbiota and SCFA levels were significantly different between the five diet groups. At a recommended dose of 20% protein in the diet, meat protein-fed rats had a higher relative abundance of the beneficial genus Lactobacillus, but lower levels of SCFAs and SCFA-producing bacteria including Fusobacterium, Bacteroides and Prevotella, compared with the soy protein-fed group. Further work is needed on the regulatory pathways linking dietary protein intake to gut microbiota.