The luxS deletion reduces the spoilage ability of Shewanella putrefaciens: An analysis focusing on quorum sensing and activated methyl cycle.

The luxS mutant strains of Shewanella putrefaciens (SHP) were constructed to investigate the regulations of gene luxS in spoilage ability. The potential regulations of AI-2 quorum sensing (QS) system and activated methyl cycle (AMC) were studied by analyzing the supplementation roles of key circulating substances mediated via luxS, including S-adenosylmethionine (SAM), S-adenosylhomocysteine (SAH), methionine (Met), homocysteine (Hcy) and 4,5-dihydroxy-2,3-pentanedione (DPD). Growth experiments revealed that the luxS deletion led to certain growth limitations of SHP, which were associated with culture medium and exogenous additives. Meanwhile, the decreased biofilm formation and diminished hydrogen sulfide (H2S) production capacity of SHP were observed after luxS deletion. The relatively lower total volatile base nitrogen (TVB-N) contents and higher sensory scores of fish homogenate with luxS mutant strain inoculation also indicated the weaker spoilage-inducing effects after luxS deletion. However, these deficiencies could be offset with the exogenous supply of circulating substances mentioned above. Our findings suggested that the luxS deletion would reduce the spoilage ability of SHP, which was potentially attributed to the disorder of AMC and AI-2 QS system.

Rapid Visual Detection of Elite Erect Panicle Dense and Erect Panicle 1 Allele for Marker-Assisted Improvement in Rice (Oryza sativa L.) Using the Loop-Mediated Isothermal Amplification Method.

Molecular-assisted breeding is an effective way to improve targeted agronomic traits. dep1 (dense and erect panicle 1) is a pleiotropic gene that regulates yield, quality, disease resistance, and stress tolerance, traits that are of great value in rice (Oryza sativa L.) breeding. In this study, a colorimetric LAMP (loop-mediated isothermal amplification) assay was developed for the detection of the dep1 allele and tested for the screening and selection of the heavy-panicle hybrid rice elite restorer line SHUHUI498, modified with the allele. InDel (Insertion and Deletion) primers (DEP1_F and DEP1_R) and LAMP primers (F3, B3, FIP, and BIP) for genotyping were designed using the Primer3 Plus (version 3.3.0) and PrimerExplore (version 5) software. Our results showed that both InDel and LAMP markers could be used for accurate genotyping. After incubation at a constant temperature of 65 °C for 60 min with hydroxynaphthol blue (HNB) as a color indicator, the color of the LAMP assay containing the dep1 allele changed to sky blue. The SHUHUI498 rice line that was detected in our LAMP assay displayed phenotypes consistent with the dep1 allele such as having a more compact plant architecture, straight stems and leaves, and a significant increase in the number of effective panicles and spikelets, demonstrating the effectiveness of our method in screening for the dep1 allele in rice breeding.

The highly stable indicator film incorporating roselle anthocyanin co-pigmented with oxalic acid: Preparation, characterization and freshness monitoring application.

A novel stable PVA/HPMC/roselle anthocyanin (RAE) indicator film co-pigmented with oxalic acid (OA) was prepared, its properties, application effects and stability enhancement mechanism were investigated correspondingly. The structural characterization revealed that more stable network was formed due to the co-pigmentation facilitated generation of molecular interactions. Meanwhile, the co-pigmentation improved film mechanical and hydrophobic properties compared to both PVA/HPMC/RAE newly prepared (PHRN) or stored (PHRS) film, expressing as higher tensile strength values (12.25% and 14.44% higher than PHRN and PHRS), lower water solubility (7.22% and 10.09% lower than PHRN and PHRS) and water vapor permeability values (33.20% and 21.05% lower than PHRN and PHRS) of PVA/HPMC/RAE/OA newly prepared (PHON) or stored (PHOS) film. Compared with the PHRS film, the PHOS film still presented more distinguishable color variations when being applied to monitor shrimp freshness, owing to the stabilization behaviors of co-pigmentation in anthocyanin conformation. Hence, the co-pigmentation was an effective strategy to enhance film stability, physical and pH-responsive properties after long term storage, leading to better film monitoring effects when applied in real-time freshness monitoring.

Rapid Visual Detection of High Nitrogen-Use Efficiency Gene OsGRF4 in Rice (Oryza sativa L.) Using Loop-Mediated Isothermal Amplification Method.

The GROWTH-REGULATING FACTOR4 (OsGRF4) allele is an important target for the development of new high nitrogen-use efficiency (NUE) rice lines that would require less fertilizers. Detection of OsGRF4 through PCR (polymerase chain reaction)-based assay is cumbersome and needs advanced laboratory skills and facilities. Hence, a method for conveniently and rapidly detecting OsGRF4 on-field is a key requirement for further research and applications. In this study, we employed cleaved amplified polymorphic sequences (CAPs) and loop-mediated isothermal amplification (LAMP) techniques to develop a convenient visual detection method for high NUE gene OsGRF4NM73 (OsGRF4 from the rice line NM73). The TC→AA mutation at 1187-1188 bp loci was selected as the target sequence for the OsGRF4NM73 allele. We further employed this method of identification in 10 rice varieties that carried the OsGRF4 gene and results revealed that one variety (NM73) carries the target OsGRF4NM73 allele, while other varieties did not possess the osgrf4 genotype. The optimal LAMP reaction using hydroxynaphthol blue (HNB), a chromogenic indicator, was carried out at 65 °C for 60 min, and the presence of OsGRF4NM73 allele was confirmed by color changes from violet to sky blue. The results of this study showed that the LAMP method can be conveniently and accurately used to detect the OsGRF4NM73 gene in rice.

Effects of pH and NaCl on the Spatial Structure and Conformation of Myofibrillar Proteins and the Emulsion Gel System-Insights from Computational Molecular Dynamics on Myosin of Golden Pompano.

In this study, the effects of pH and NaCl concentrations on the structure of golden pompano myosin and emulsion gel were analyzed using SEM in combination with molecular dynamics simulations (MDS). The microscopic morphology and spatial structure of myosin were investigated at different pH (3.0, 7.0, and 11.0) and NaCl concentrations (0.0, 0.2, 0.6, and 1.0 M), and their effects on the stability of emulsion gels were discussed. Our results show that pH had a greater effect on the microscopic morphology of myosin than NaCl. The MDS results show that under the condition of pH 7.0 and 0.6 M NaCl, the myosin expanded and experienced significant fluctuations in its amino acid residues. However, NaCl showed a greater effect on the number of hydrogen bonds than pH. Although changes in pH and NaCl concentrations only slightly altered the secondary structures in myosin, they, nevertheless, significantly influenced the protein spatial conformation. The stability of the emulsion gel was affected by pH changes but not NaCl concentrations, which only affect the rheology. The best elastic modulus G″ of the emulsion gel was obtained at pH 7.0 and 0.6 M NaCl. Based on the results, we conclude that pH changes have a greater influence than NaCl concentrations on the spatial structure and conformation of myosin, contributing to the instability of its emulsion gel state. The data from this study would serve as a valuable reference for emulsion gel rheology modification in future research.

Improved thermal stability of roselle anthocyanin by co-pigmented with oxalic acid: Preparation, characterization and enhancement mechanism.

The enhancement effects of co-pigmentation on thermal stability of roselle anthocyanin extract (RAE) were investigated. The introduction of organic acids maintained color stability of RAE, and RAE co-pigmented with oxalic acid (OA) presented less color fading rates (19.46 ± 0.33 %) and higher redness (41.33 ± 3.51). Subsequently, suitable co-pigmentation concentration (OA:RAE = 1:2) was obtained regarding with lower ΔE (48.70 ± 2.36). Then, improvement behaviors of co-pigmentation on OA-RAE were evaluated. Results demonstrated that OA-RAE exhibited better thermal stability, as manifested by larger retention rates and more favorable thermal degradation kinetic parameters. Furthermore, both molecular docking simulation and experimental structural characterization revealed that hydrogen bonds and other non-covalent bonds made up the main parts of molecular interactions, leading to formation of stable binary complex. As a result, the aromatic ring of RAE was protected. In conclusion, the co-pigmentation of RAE via introduction of OA was effective in stability enhancement due to the generation of molecular bindings.

Differentiation of three commercial tuna species through Q-Exactive Orbitrap mass spectrometry based lipidomics and chemometrics.

Mislabeling and adulteration of tuna are common due to the diminishing of morphological characteristics during processing. The tuna authenticity is now being focused in the seafood supply chain. In this study, the lipid profiles of 3 commercial tuna species (skipjack tuna, bigeye tuna and yellowfin tuna) were investigated via ultra-high performance liquid chromatography coupled with Q-Exactive Orbitrap mass spectrometry (UPLC-Q-Exactive Orbitrap MS). A total of 439 lipid species were identified and semi-quantitated by MS-DIAL. Further biomarkers discovery was carried out by chemometrics, leading to 27 lipids being identified as potential lipid biomarkers. Comparisons to reference standards revealed that lipid biomarkers were effective for discrimination of different tuna species. Interestingly, the proposed lipid biomarkers were all glycerophospholipids, implying that they might be the focus of future study.

Identification of curcumin as a potential α-glucosidase and dipeptidyl-peptidase 4 inhibitor: Molecular docking study, in vitro and in vivo biological evaluation.

Natural compounds have tremendous potential to regulate glucose metabolism, but conventional methods for studying their bioactivities are usually labor intensive. Here, hypoglycemic properties in 22 selected food-derived compounds were examined using molecular docking. The results indicated that curcumin is an inhibitor of both α-glucosidase and dipeptidyl-peptidase 4 (DPP-4), which are important for glycemic control. These effects of curcumin were also confirmed by enzymatic determination in vitro. Furthermore, curcumin significantly improved diet-induced hyperglycemia (e.g., fasting plasma glucose levels and glycogen storage in muscle or liver) in mice. This might be attributed to its inhibitory effects on the activities of α-glucosidase and DPP-4 in vivo. Curcumin also upregulated the expression of genes (e.g., glucagon-like peptide 1) related to DPP-4 activity in the small intestine. In conclusion, curcumin is a potential ingredient of functional foods used for diet-induced hyperglycemia management. PRACTICAL APPLICATIONS: Curcumin has been widely used as a colorant in the food industry. Moreover, a growing number of studies have described its diverse biological functions, such as anti-inflammatory, anti-oxidant, and anti-angiogenic activities. Thus, curcumin is regarded as a potential ingredient in functional foods. Our results highlighted the hyperglycemic effect of curcumin, suggesting that curcumin may be included in food products for hyperglycemic patients.

Sun-Dried and Air-Dried Kappaphycus alvarezii Attenuates 5-Fluorouracil-Induced Intestinal Mucositis in Mice.

5-fluorouracil (5-FU)-induced intestinal mucositis (IM) often makes chemotherapy patients suffer from physical and psychological suffering. Kappaphycus alvarezii (KA) is known for its potent multiple biological activities from decades. In the current study, we explored the effect of sun-dried and air-dried Kappaphycus alvarezii as a whole food supplement on 5-FU-induced IM. Diets supplemented with sun-dried Kappaphycus alvarezii (SKA, 3%), air-dried Kappaphycus alvarezii (AKA, 3%), and 5-aminosalicylic acid (0.005%) for consecutive14 days. While intraperitoneal injection of 5-FU (50 mg/kg) induced IM for last three consecutive days, and IM was assessed by the disease activity index (DAI) and inflammatory cytokine levels. Pretreatment of KA could alleviate phenotypic index, inhibit the increase of DAI, and reverse villus/crypt ratio. On the 14th day, AKA significantly increased the weight growth rate of the mice. The intervention of SKA significantly reduced the level of TNF-α and IL-1ß (P < 0.01, P < 0.01), while the intervention of AKA significantly inhibited the level of TNF-α, IL-1ß, and LT (P < 0.01, P < 0.01, P < 0.001). Therefore, these results showed that KA as a whole food supplement might be prevent the 5-FU-induced IM. For the first time suggest that the use of AKA might be more effective than SKA despite exact mechanism still needs further study.

Transcriptome analysis reveals the protective role of fructo-oligosaccharide in colonic mucosal barriers in exercise-induced stressed mice.

Most athletes continually endure mental and physical stress from intense exercise. Fructo-oligosaccharide (FOS) can reduce physical exhaustion, but the concrete mechanism behind it still needs further research. In this study, the effect of FOS on colonic mucosal barriers was investigated using an exercise-induced stress mouse model. Except for control individuals, mice were subject to cycles of 2-day exercise (at 20 rpm) interleaved by 5-day rest. The mice experienced a total of 6 days of exercise during the feeding period. FOS improved common indicators of exhaustion, such as glycogen storage in muscle. 16S rRNA data supported that changes in the gut microbiome were also closely related to stress status. Notably, Anaerotruncus was increased in mice under stress, while FOS facilitated the growth of Dorea, which is negatively associated with exhaustion. The RNA-seq analysis revealed that FOS could maintain the integrity of colonic epithelial barriers. For example, FOS significantly restored the expression of tight junctions (Occludin and Zonula occludens-1) in the colon, which was impaired under a stress state. Besides, the NOD-like receptor family pyrin domain containing 6 (NLRP6) inflammasome might contribute to the protection of the colonic mucosa by promoting the secretion of IL-18, Mucin2 (Muc2) and intestine lectin 1 (Itln1) in FOS-treated individuals. In short, FOS administration attenuated the damage of colonic mucosal barriers in exercise-induced stressed mice.

Astaxanthin n-Octanoic Acid Diester Ameliorates Insulin Resistance and Modulates Gut Microbiota in High-Fat and High-Sucrose Diet-Fed Mice.

Astaxanthin n-octanoic acid diester (AOD) is a type of astaxanthin connecting medium-chain fatty acids with a more stable structure. In this study, we examined the role of AOD in ameliorating insulin resistance (IR) induced by a high-fat and high-sucrose diet (HFD) as well as its effect on modulating gut microbiota in mice, with free astaxanthin (AST) as a comparison. Four groups of male C57BL/6J mice (6 weeks old; n = 10 per group) were fed with a normal control diet (NC), HFD orally administered with AOD, AST (50 mg/kg body weight), or vehicle for 8 weeks. AOD improved glucose tolerance, IR, systematic and intestinal inflammation, and intestinal integrity better than AST. Further, both AOD and AST modulated gut microbiota. A significantly higher abundance of Bacteroides and Coprococcus was found in AOD than in AST, and the predicted pathway of carbohydrate metabolism was significantly impacted by AOD. Overall, AOD may play a role in alleviating IR and inflammation with the modulating effect on microbiota in HFD-fed mice. Our findings could facilitate the development of AOD as a bioactive nutraceutical and more stable alternative to AST.

The role of gut microbiota in the resistance to obesity in mice fed a high fat diet.

The prevalence of diet induced obesity (DIO) is a huge threat to global health. Differences in gut microbiota may be concerned with DIO. Sixty male C57BL/6J mice were fed with high fat diet (HFD, 45% kcal from fat) for 16 weeks. Among them, body weight, body fat rate and the lipid content in plasma or liver of six mice (Lean (L) group) were obviously lower than average levels (Fatty (F) group). These results supported that some individuals were resistant to HFD induced obesity. Using 16S rRNA analysis to investigate the role of gut microbiota in this resistance, we found several alterations associated with the resistance, such as an increase of Muribaculaceae in L group. Moreover, analysis of predicted microbial function suggested that bacteria in F group could better utilise HFD compared to L group. In conclusion, gut microbiota might play a bigger role than diet in resisting obesity, and it could be a potential target for obesity treatment.

DHA-phospholipids (DHA-PL) and EPA-phospholipids (EPA-PL) prevent intestinal dysfunction induced by chronic stress.

Stress exposure can increase the appearance of intestinal dysfunction. DHA and EPA have been shown to possess significant anti-inflammatory and immuno-enhancement bioactivities. The aim of the study was to investigate whether different forms of DHA or EPA would affect intestinal barriers (including intestinal epithelium integrity and immunity responses, gut microbiota and its metabolites) in mice under chronic stress, and might therefore prevent stress induced intestinal dysfunction. Chronic stress caused a series of anomalies in the intestine, including decreased faecal water content, increased pro-inflammatory cytokines (IFN-γ, TNF-α, IL-1ß and IL-6), reduced expression levels of ZO-1, occludin and E-cadherin, and aberrant microbiota composition (especially Roseburia spp., Prevotella spp., bifidobacteria and lactobacilli) and its metabolites, mainly LPS, acetic acid, propionic acid and butyric acid. Our data indicated that both DHA-PL and EPA-PL counteracted these adverse effects effectively. In conclusion, DHA-PL and EPA-PL may effectively protect mice against intestinal dysfunction under chronic stress exposure as potential ingredients for functional food.

Potential Bioactive Compounds from Seaweed for Diabetes Management.

Diabetes mellitus is a group of metabolic disorders of the endocrine system characterised by hyperglycaemia. Type II diabetes mellitus (T2DM) constitutes the majority of diabetes cases around the world and are due to unhealthy diet, sedentary lifestyle, as well as rise of obesity in the population, which warrants the search for new preventive and treatment strategies. Improved comprehension of T2DM pathophysiology provided various new agents and approaches against T2DM including via nutritional and lifestyle interventions. Seaweeds are rich in dietary fibres, unsaturated fatty acids, and polyphenolic compounds. Many of these seaweed compositions have been reported to be beneficial to human health including in managing diabetes. In this review, we discussed the diversity of seaweed composition and bioactive compounds which are potentially useful in preventing or managing T2DM by targeting various pharmacologically relevant routes including inhibition of enzymes such as α-glucosidase, α-amylase, lipase, aldose reductase, protein tyrosine phosphatase 1B (PTP1B) and dipeptidyl-peptidase-4 (DPP-4). Other mechanisms of action identified, such as anti-inflammatory, induction of hepatic antioxidant enzymes' activities, stimulation of glucose transport and incretin hormones release, as well as ß-cell cytoprotection, were also discussed by taking into consideration numerous in vitro, in vivo, and human studies involving seaweed and seaweed-derived agents.