Exploring the novel antioxidant peptides in low-salt dry-cured ham: Preparation, purification, identification and molecular docking.

Dry-cured ham is important source of bioactive peptides. In this study, the antioxidant activities of peptides and components from low and fully salted dry-cured hams were compared by peptidomics. And novel antioxidant peptides were identified and characterized. The results showed that the peptides (<3 KDa) extracted from low-salt dry-cured ham had higher antioxidant activity. Therefore, the antioxidant peptides in low-salt dry-cured ham were further characterized and the mechanism of their antioxidant activity was investigated. From the five candidate peptides selected, we found DWPDARGIWHND (DD12) to be highly stable, non-sensitizing, and non-toxic with the highest free radical scavenging activity. Molecular docking predicted that DD12 interacted with Keap1 through hydrogen-bond formation and hydrophobic interactions, suggesting that DD12 had good cellular antioxidant activity. DD12 peptide can bind to DPPH• and ABTS•+, resulting in strong free radical scavenging activity. Our findings support the development and application of natural antioxidant peptides in dry-cured ham.

Correction to: Bioactive compounds and antioxidant activities of Quercus salicina Blume extract.

[This corrects the article DOI: 10.1007/s10068-020-00755-1.].

Plasma TIGIT Level Is a Possible Marker in HIV-Related Liver Damage.

T cell immunoglobulin and ITIM domain (TIGIT), has a key role in immunopathogenesis of HIV. Previous studies on immune checkpoint receptors had mainly focused on the membrane form. To evaluate clinical significance of soluble form of TIGIT (sTIGIT) in people living with HIV. Blood samples of 61 untreated HIV-infected patients and 24 healthy individuals were collected and TIGIT concentrations in plasma were measured by ELISA method. A decreased level of plasma TIGIT in HIV-infected patients was found to be negatively associated with AST/ALT ratio (r = -0.5358, p = 0.0483) that was indicative of liver damage. Moreover, the proportion of TIGIT on CD3+CD4+ cells in HIV-infected individuals increased (47.12 ± 5.051%) compared with in healthy controls (22.13 ± 4.426%, p < 0.01), which indicated change in plasma TIGIT level was at least partially attributed to CD3+CD4+ T cells. Furthermore, there was a strong positive correlation between TIGIT plasma levels and lymphocyte activation gene-3 (LAG-3) plasma levels in HIV-infected patients with a linear correlation coefficient r = 0.904. Therefore, plasma TIGIT level is a possible marker in HIV-related liver damage and LAG-3 closely related to TIGIT possibly plays a co-ordinated role in HIV-related liver damage.

Influence of different temperatures on brining kinetics, salt concentration and texture properties of Chinese cabbage (Brassica rapa L. ssp. pekinensis) during brining with ultrasonic treatment.

The effects of ultrasound treatment at different temperatures (4, 10, and 25 ℃) on the brining process of Chinese cabbage were investigated based on their salt diffusion coefficients and texture profiles. Salt weight increased significantly, but water weight decreased in Chinese cabbage treated with ultrasound at increasing temperatures. According to Fick's second equation, the effective diffusion coefficient of Chinese cabbage showed a notable increase as temperature was increased. High temperature caused unfavorable texture properties, and among these, hardness showed the most significant decrease when brining temperature was set at 25 °C. Consequently, results from the texture profile analysis and brining kinetics modeling suggest that optimal brining conditions could be achieved at 10 °C. At this temperature, the diffusion coefficient of Chinese cabbage is higher, the brining time is reduced, and the preferred qualities of kimchi are preserved. PRACTICAL APPLICATION: Ultrasonication is an effective technology that can be utilized in kimchi manufacturing. It presents the advantage of reducing brining time while maintaining the acceptable textural properties of kimchi. This study investigated the impact of different temperatures on the texture properties and brining times of Chinese cabbage during brining and reveal a practical application worthy of further study in food industries and provide valuable information for improving the quality of kimchi.

Bioactive compounds and antioxidant activities of Quercus salicina Blume extract.

Quercus salicina Blume (QS) is an oak species that is indigenous to Japan and Korea. Historically, extracts of leaves, stems, barks and buds from the QS tree had been extensively utilized as herbal medicines. As rich sources of natural antioxidants, QS extracts could prevent oxidative stress and the occurrence of related neurodegenerative diseases. In pharmaceutical applications, decoction or infusion of comminuted QS powder is prepared as an herbal tea for oral use. Various extraction methods and extracting mediums showed the potential antioxidant activities of QS extracts, as well as the different types and levels of bioactive compounds found in them. Due to their functional properties and possibly low-level of cytotoxicity, the potential application of QS extracts as a novel food ingredient could be considered. In this review paper, a brief overview about QS extracts and their bioactive components, antioxidant activities, toxicity and technological applications is described based on previous works.

Shotgun metagenomics approach reveals the bacterial community and metabolic pathways in commercial hongeo product, a traditional Korean fermented skate product.

The aim of this study was to investigate the microbial diversity and microbial metabolic pathways using a metagenomic approach in commercial hongeo samples collected from five different fish processing plants. Community comparison analysis indicated that hongeo samples from different fish processing plants have a similar microbial structure at genus level, but the relative abundance of these genera showed a significant difference among different hongeo samples. Four bacterial genera including Psychrobacter, Pseudomonas, Clostridium, and Oblitimonas were detected in all hongeo samples with a high relative abundance, which associated with the nitrogen compound accumulation and ammonia flavor formation in hongeo samples. In addition, some alkaliphilic marine lactic acid bacteria (LAB) belonging to the genera Marinilactibacillus and Jeotgalibaca were detected in hongeo samples, indicating that this product might be a useful source for finding novel bacteria and possibly marine LAB. Through functional profiling analysis, it was found that hongeo samples had higher bacterial gene content related to amino acid metabolism, followed by carbohydrate metabolism and inorganic ion metabolism. The results of this study provide an important information for understanding the mechanism of quality characteristics and ammonia flavor formation in hongeo products.

Quantitative proteomic analysis reveals that Luks-PV exerts antitumor activity by regulating the key proteins and metabolic pathways in HepG2 cells.

Hepatocellular carcinoma (HCC) is a complicated and poor prognosis cancer, necessitating the development of a potential treatment strategy. In this study, we initially revealed that LukS-PV belonged to leukocidin family performs an anti-HCC action. Then, we used liquid chromatography-mass spectrometry (LC/MS) to compare protein expression profiles of the LukS-PV-treated human HCC cell lines HepG2 and the control cells. GO annotations and Kyoto Encyclopedia of Genes and Genomes pathway analysis were carried out of differential expression followed by protein-protein interactome, to explore the underlying cancer suppressor mechanisms of LukS-PV for human HCC. A total of 88 upregulated proteins and 46 downregulated proteins were identified. The top 10 proteins identified by the MCC method are FN1, APP, TIMP1, nucleobindin-1, GOLM1, APLP2, CYR61, CD63, ENG, and CD9. Our observation on protein expression indicated that LukS-PV produces a signature affecting central carbon metabolism in cancer, galactose metabolism, and fructose and mannose metabolism pathways. The results give a functional effects and molecular mechanism insight, following LukS-PV treatment.

LukS-PV induces apoptosis in acute myeloid leukemia cells mediated by C5a receptor.

LukS-PV is one of the two components of Panton-Valentine leucocidin (PVL). Our previous study showed that LukS-PV can induce apoptosis in human acute myeloid leukemia (AML) THP-1 and HL-60 cells. C5aR (C5a receptor) is the receptor for PVL, but whether C5aR plays a key role in LukS-PV induced apoptosis is unclear. The aim of this study was to establish whether C5aR plays a physiological role in apoptosis of leukemia cells induced by LukS-PV. We investigated the role of C5aR in leukemia cell apoptosis induced by LukS-PV by pretreatment of THP-1 and HL-60 cells with C5aR antagonist and transfection to knockdown C5aR in THP-1 cells or overexpress C5aR in Jurkat cells before treatment with LukS-PV. Cell apoptosis was analyzed by staining with Annexin V/propidium iodide or Annexin V-PE/7-AAD. Mitochondrial membrane potential (MMP) was determined using JC-1 dye. The expression of apoptosis-associated genes and proteins was identified by qRT-polymerase chain reaction and Western blotting analysis, respectively. As the C5aR antagonist concentration increased, the rate of apoptosis induced by LukS-PV decreased, the MMP increased, and expression of pro-apoptotic Bax and Bak genes and proteins was downregulated while that of anti-apoptotic Bcl-2 and Bcl-x genes and proteins was upregulated. Knockdown of C5aR also decreased LukS-PV-induced THP-1 cell apoptosis. LukS-PV did not induce apoptosis of Jurkat cells, which have no endogenous C5aR expression; however, LukS-PV did induce apoptosis in Jurkat cells after overexpression of C5aR. Correspondingly, the MMP decreased and Bax and Bak were upregulated while Bcl-2 and Bcl-x were downregulated. LukS-PV can induce apoptosis in AML cells by targeting C5aR. C5aR may be a potential therapeutic target for AML and LukS-PV is a candidate targeted drug for the treatment of AML.

Isolation and identification of hyper-ammonia-producing bacteria from commercial fermented skates (Raja kenojei).

Ammonia-producing bacteria were isolated and identified from five commercial fermented skates (A1, A2, A3, A4, and A5). In addition, the pH, ammonia nitrogen, total volatile nitrogen (TVBN), trimethylamine nitrogen (TMAN), and amino nitrogen contents of skate samples were also determined. A total of 88 strains of ammonia-producing bacteria was isolated and seven hyper-ammonia-producing bacteria isolates (A2-2, A2-3, A2-12, A2-18, A2-20, A3-6 and A3-14) were selected based on ammonia nitrogen producing ability. Those isolates were identified as Proteus hauseri (three strains), Providencia rustigianii (three strains), and Kurthia gibsonii. The pH and ammonia nitrogen content in skate samples were ranged from 8.63 to 9.03, and 4.86 to 7.31 g/kg, respectively. No significant difference of pH values was observed in skate samples A2, A3, A4 and A5. While, skate samples A3, A4 and A5 showed similar level of TVBN and TMAN content. Skate sample A2 showed the highest amino nitrogen content among all samples, which indicated the highest degree of protein degradation of skate muscle during fermentation. Bivariate cluster analysis showed that skate samples A3, A4, and A5 clustered together at a relatively high level, implying a similar microbial environment during fermentation. The cluster analysis allowed different commercial fermented skates to be clearly differentiated based on the characteristics determined in this study. This study can provide important information for investigating the mechanisms underlying ammonia flavor formation in skate muscle during fermentation.

Influence of ultrasound application and NaCl concentrations on brining kinetics and textural properties of Chinese cabbage.

The effects of ultrasound application on the brining kinetics of Chinese cabbage leaves was evaluated at different NaCl concentrations (10, 15, and 20%) of the brine, and its influence on textural properties and salt distribution was also investigated. To identify the effects of these two factors on water and NaCl fluxes, the kinetics of transport was analyzed by taking the diffusion theory into account. The results showed that NaCl concentration and ultrasound application significantly affected moisture and NaCl transport. Based on Fick's equation, the NaCl effective diffusivities were enhanced upon ultrasound application during the brining process, increasing from 147.09 to 812.22%. With regard to the textural properties, a higher content of NaCl resulted in lower textural profile values. Moreover, ultrasound application significantly increased the cabbage hardness. Scanning electron microscopy and energy dispersive X-ray mapping images showed the intensification of NaCl transport brought about by ultrasound application and by the increase in NaCl content, which confirms the results of the modeling analysis. Therefore, ultrasound could be a potential technology for accelerating the brining process of cabbage. These results have direct implications for the quality management of kimchi products.

[Morphological Characteristics and Molecular Identification of Trichuris sp. from Giraffe].

Objective: To investigate the morphological characteristics of Trichuris sp. from giraffe in Hefei wild zoo and identify its species using molecular techniques. Methods: Morphological characteristics of Trichuris collected from giraffe were analyzed. The internal transcribed spacer 1（ITS-1） was amplified by PCR and the PCR product was sequenced. The resulting sequence was homology analysis in GenBank and its heredity evolution tree was constructed by MEGA 4.0 software. Results: The male worms had a body length of 35.89-58.56 mm, an esophagus to body length ration of 0.29-0.40, and a spicule length of 1.96-3.89 mm. The thick and thin proportions of body were 7.02-23.45 mm and 28.05-40.05 mm respectively. These data showed different degrees of variation with previous reports. The PCR resulted in a product of 491 bp, comprising part of 18S rRNA and full length ITS-1. Sequence alignment showed that the identified Trichuris was most homologous（98.6%） with T. bos taurus HE608848, T. capreolus JX218218, and T. japanese AB367795, but it was only 46.0% homologous with T. discolor AB367794. In the heredity evolution tree, it was not located on the same branch as T. discolor, T. ovis and T. bos taurus. Conclusions: The Trichuris sp. collected from giraffe is different from previous reports in morphology and ITS-1 sequence. Further research is needed to determine if it is a new species.

[Establishment of LAMP Detection for Toxoplasma gondii Based on the 529 bp Repeat Sequence].

Objective: To establish the loop mediated isothermal amplification（LAMP） technique for determining Toxoplama gondii. Methods: The primers for LAMP of the conserved 529 bp sequence was designed by the Primer Explorer 4.0 software. The LAMP reaction was made on the constructed pMD-19T-529 bp recombinant plasmid as a template, and was optimized in loop primer, concentrations of betaine and MgSO4, and reaction temperature. The optimized LAMP and PCR were performed in ultra-pure water, on pig genome, Cryptosporidium parvum genome, Isospora suis genome, and pMD-19T-529 bp, respectively, to test the sensitivity of LAMP. The pMD-19T-529 bp was serially diluted to 109-100 copies/ml to test the specificity of LAMP. Results: LAMP using the designed primers amplified the 529 bp fragment of T. gondii. The optimized LAMP system had a total reaction volume of 25 µl, with the optimal concentrations of betaine and MgSO4 being 0.4 mol/L and 6 mmol/L, respectively. The amplification efficiency of 30 min reaction in the presence of loop primer was comparable to that of 60 min reaction without loop primer, which indicated that addition of loop primer shortened the reaction time by 30 min. The optimal reaction condition was 63 ℃ 30 min, 80 ℃ 3 min. The established LAMP method specifically amplifed the 529 bp fragment of T. gondii, and its efficiency was 10 times of PCR（detection threshold 103 copies/ml vs. 104 copies/ml）. Conclusion: The established LAMP for detecting Toxoplama gondii 529 bp repeat sequence shows high specificity and sensitivity.

Interleukin-21 up-regulates interleukin-21R expression and interferon gamma production by CD8+ cells in SHIV-infected macaques.

Interleukin-21 (IL-21) is produced primarily by CD4+ T cells and regulates immunity against human/simian immunodeficiency virus (HIV/SIV) infection. Activated CD8+ cells and their secreted interferon-gamma (IFN-γ) are crucial for the control of acute HIV/SIV infection. However, whether IL-21 can regulate IFN-γ production by CD8+ cells remains controversial. Rhesus macaques (RMs, n = 8) were infected with SHIV and the levels of plasma IL-21, IFN-γ and the frequency of peripheral blood activated T cells were measured longitudinally. Following infection with SHIV, the levels of plasma IL-21 and IFN-γ increased, peaked at 17 days postinfection and declined later. Furthermore, IL-21 induced IL-21 receptor (IL-21R) and IFN-γ, perforin, but not granmyze B, expression in CD8+ cells from four selected SHIV-infected RMs. The regulatory effect of IL-21 on CD8+ cell function appeared to be associated with increased levels of STAT3, but not STAT5, phosphorylation in CD8+ cells from SHIV-infected RMs. In parallel, treatment with soluble IL-21R/Fc, an inhibitor of IL-21-induced activation of JAK1/3 and STAT3, abrogated IL-21-induced STAT3 activation and IFN-γ production in CD8+ cells from SHIV-infected RMs in vitro. Our data indicated that IL-21 was a positive regulator of IFN-γ-secreting CD8+ cells and increased the STAT3 phosphorylation, regulating T-cell immunity against acute SHIV infection in RMs. Our findings may provide a new basis for the development of immunotherapies for the control of SHIV/HIV infection.

Circulating IL-21 levels increase during early simian-human immunodeficiency virus infection in macaques.

The cytokine interleukin-21 (IL-21) regulates viral pathogenesis in individuals infected with human and simian immunodeficiency viruses. However, because the time of initial infection with HIV in humans is rarely known, the dynamics of IL-21 production during the first weeks have not been adequately explored. In the present study, we used rhesus macaques to model the first stages of infection. Twenty-two rhesus macaques were infected rectally with simian-human immunodeficiency virus (SHIV)-1157ipd3N4, and for 12 weeks, replication of the virus, the numbers of CD4+ and CD8+ T cells, and the levels of plasma IL-21 were monitored. Our study demonstrated that plasma levels of IL-21 increased during the early phase of SHIV infection when compared with the values observed before inoculation. We conclude that IL-21 has a likely role in the immunopathogenesis of HIV/SIV/SHIV.

[Detection of immunity and antioxidant indexes in dairy cows infected with Cryptosporidium].

OBJECTIVE: To detect the immune status and antioxidant system indexes of cows infected with Cryptosporidium. METHODS: Fecal samples of 325 dairy cows were collected at a farm in Anhui and examined by floating saturated solution. 7 positive cows and 7 negative cows from the farm were selected as infection group and non-infection group, respectively. Blood samples were taken from cow's jugular vein before feeding in the morning. 19 indexes of total protein (TP), albumin (ALB), IgG, IgM, IgA, phagocytic rate of white blood cells, T lymphocyte transformation rate, IL-2, superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), malondialdehyde (MDA), NO, alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), glucose (GLU), triglyceride (TG), Cl-, and Ca2+ were tested, respectively. RESULTS: The infection rate of 325 cows was 31.7% (103/325). The Cryptosporidium was identified as C. andersoni according to the morphology and size of oocysts. Compared with the non-infection group, there was no significant difference in the concentration of TP, ALB, IgM, IgA, GSH-Px, ALT, AST, ALP and Cl- (P > 0.05). The concentration of MDA and NO in the infection group increased by 59.9% and 28.1% (P < 0.05 or 0.01), and that of IgG, SOD, GLU, TG, Ca2+, IL-2 and the activities of T lymphocyte transformation rate, phagocytic rate of white blood cells decreased by 32.9%, 11.1%, 18.6%, 78.9%, 14.5%, 7.0%, 22.0%, and 20.2%, respectively (P < 0.05). CONCLUSION: The change of antioxidant and immune indexes shows that the capability of eliminating free radicals and the immune function have decreased in the Cryptosporidium andersoni-infected cows.

[Isolation and identification of cow-origin Cryptosporidium isolates in Hefei].

OBJECTIVE: To isolate cow-origin Cryptosporidium in Hefei, and identify its species. METHODS: 285 dairy cattle fecal samples collected from a farm in Hefei were examined by using floating saturated solution of sucrose and modified acid-fast staining. Cryptosporidium oocysts were isolated and purified from positive fecal samples. Genetic DNA was extracted to be the template. According to the sequence of 18S rRNA gene and HSP70 gene from Cryptosporidium sp., the primers were designed and synthesized. The PCR products were amplified by PCR and nested-PCR. The nested PCR products were cloned and sequenced. Homology searches and phylogenic tree construction were done by DNAStar software. RESULTS: Five fecal samples were positive by morphological methods with an infection rate of 1.8% (5/285). Oocysts from the 5 positive fecal samples were elliptical or ovoid detected by using floating saturated solution of sucrose and modified acid-fast staining with the size of 7.37 microm x 6.13 microm and 7.58 microm x 6.20 microm, and a shape index of 1.20 and 1.22, respectively. Nested-PCR resulted in a 18S rRNA and HSP70 gene fragments with approximately 250 bp and 325 bp, respectively. The five isolates showed a high level of nucleic acid identity with sequence data of the 18S rRNA gene of Cryptosporidium andersoni (DQ989573), and they were clustered in the same clade. The highest HSP70 gene sequence identity was found among the five isolates and other reported C. andersoni isolates (AY954892 and DQ989576), and they were placed into the same clade. CONCLUSION: The cow-origin Cryptosporidium isolates derived from Hefei is Cryptosporidium andersoni.