Preparation and Characterization of Chloroprene Latexes Modified with Vinyl-POSS.

Water-based chloroprene latex is a solvent-free, environmentally friendly adhesive. Currently, its market demand is growing rapidly. However, there are problems such as a lack of heat resistance and poor mechanical properties, which limit its application. The introduction of vinyl-POSS (OVS) into the resin structure can effectively improve the thermal stability of chloroprene adhesives. In this paper, modified waterborne chloroprene latex was prepared by copolymerization of methyl methacrylate and OVS with chloroprene latex. The results showed that vinyl-POSS was successfully grafted onto the main chain of the waterborne chloroprene latex, and the modified waterborne chloroprene latex had good storage stability. With the increase in vinyl-POSS, the tensile strength of the chloroprene latex firstly increased and then decreased, the tensile property (peel strength of 20.2 kgf) was maintained well at a high temperature (100 °C), and the thermal stability of the chloroprene latex was improved. When the addition amount was 4%, the comprehensive mechanical properties were their best. This study provides a new idea for the construction of a new and efficient waterborne chloroprene latex system and provides more fields for the practical application of waterborne chloroprene latex. This newly developed vinyl-POSS modified chloroprene latex has great application potential for use in home furniture, bags, and seat cushions.

CD4/CD8 Ratio Recovered as a Predictor of Decreased Liver Damage in Adults Infected With HIV: 16-Year Observational Cohort Study.

BACKGROUND: As the life expectancy of individuals infected with HIV continues to increase, vigilant monitoring of non-AIDS-related events becomes imperative, particularly those pertaining to liver diseases. In comparison to the general population, patients infected with HIV experience a higher frequency of liver-related deaths. The CD4/CD8 ratio is emerging as a potential biomarker for non-AIDS-related events. However, few existing studies have been specially designed to explore the relationship between the CD4/CD8 ratio and specific types of non-AIDS-related events, notably liver damage. OBJECTIVE: This study aimed to investigate the potential association between the CD4/CD8 ratio and the development of liver damage in a sizable cohort of patients infected with HIV receiving antiretroviral treatment (ART). Additionally, the study sought to assess the effectiveness of 3 antiretroviral drugs in recovering the CD4/CD8 ratio and reducing the occurrence of liver damage in this population. METHODS: We conducted an observational cohort study among adults infected with HIV receiving ART from 2004 to 2020 in Guangxi, China. Propensity score matching, multivariable Cox proportional hazard, and Fine-Gray competing risk regression models were used to determine the relationship between the CD4/CD8 ratio recovered and liver damage. RESULTS: The incidence of liver damage was 20.12% among 2440 eligible individuals during a median follow-up period of 4 person-years. Patients whose CD4/CD8 ratio did not recover to 1.0 exhibited a higher incidence of liver damage compared to patients with a CD4/CD8 ratio recovered (adjusted hazard ratio 7.90, 95% CI 4.39-14.21; P<.001; subdistribution hazard ratio 6.80, 95% CI 3.83-12.11; P<.001), findings consistent with the propensity score matching analysis (adjusted hazard ratio 6.94, 95% CI 3.41-14.12; P<.001; subdistribution hazard ratio 5.67, 95% CI 2.74-11.73; P<.001). The Efavirenz-based regimen exhibited the shortest time for CD4/CD8 ratio recovery (median 71, IQR 49-88 months) and demonstrated a lower prevalence of liver damage (4.18/100 person-years). CONCLUSIONS: Recovery of the CD4/CD8 ratio was associated with a decreased risk of liver damage in patients infected with HIV receiving ART, adding evidence for considering the CD4/CD8 ratio as a potential marker for identifying individuals at risk of non-AIDS-related diseases. An efavirenz-based regimen emerged as a recommended choice for recovering the CD4/CD8 ratio and mitigating the risk of liver damage.

Trends and associated factors of HIV, HCV and syphilis infection among different drug users in the China-Vietnam border area: an 11-year cross-sectional study (2010-2020).

BACKGROUND: Data on recent human immunodeficiency virus (HIV), hepatitis C virus (HCV) and syphilis prevalence among drug users in the Southwest China are sparse despite the high burden of drug use. This study aims at assessing the prevalence trends and related factors of HIV, HCV and syphilis infection among different drug users in the China-Vietnam border area. METHODS: A continuous cross-sectional survey was conducted among drug users from 2010 to 2020 in the China-Vietnam border area. Chi-square trend tests were used to assess the trend of HIV, HCV and syphilis prevalence and the proportion for drug type used by drug users. Multivariate logistic regression was used to identify associated factors of HIV, HCV and syphilis infection in different drug users. RESULTS: In this study, a total of 28,951 drug users were included, of which 27,893 (96.45%) male, 15,660 (54.09%) aged 13-34 years, 24,543 (84.77%) heroin-only users, 2062 (7.12%) synthetic drug-only (SD-only) users and 2346 (8.10%) poly-drug users. From 2010 to 2020, the proportion of heroin-only users decreased from 87.79% to 75.46%, whereas SD-only users and poly-drug users increased from 5.16% to 16.03%, and from 7.05% to 8.52%, respectively. The prevalence of HIV, HCV, and syphilis during the study period declined from 12.76%, 60.37% and 5.72% to 4.35%, 53.29% and 4.53%, respectively, among heroin-only users and declined from 18.30%, 66.67% and 15.69% to 6.95%, 27.81% and 5.35%, respectively, among poly-drug users; however, the prevalence of HIV and HCV among SD-only users increased from 0.89% and 8.93% to 2.84% and 18.75%, respectively. Having ever injected drugs and needle sharing were common associated factors for both HIV and HCV infection among poly-drug users and heroin-only users. Aged ≥ 35 years old was an associated factor for HIV, HCV and syphilis infection among the SD-only users. Female drug users were at high risk of contracting syphilis among three different drug users. CONCLUSIONS: The prevalence of HIV, HCV and syphilis among heroin-only users and poly-drug users decreased during the study period. However, the prevalence of HIV and HCV among SD-only users increased. Comprehensive intervention strategies, particularly focusing on the SD-only users are needed in order to bring down the disease burden in this population in the China-Vietnam border areas.

Prevalence, Trends and Correlates of HIV, Syphilis and HCV Infection Among Chinese Local and Cross-border Migrant Female Sex Workers in the Sino-Vietnam Border Area of Guangxi, 2016-2021.

Female sex workers (FSWs) are considered a high-risk group for sexually transmitted infections (STIs). However, limited data exist on the prevalence and trends of HIV, syphilis and HCV among FSWs in the Sino-Vietnam border area. To determine the prevalence, trends and correlates of STIs among Chinese local FSWs (CL-FSWs) and cross-border migrant FSWs (CM-FSWs), we conducted consecutive cross-sectional surveys from 2016 to 2021, recruiting 7747 CL-FSWs and 932 CM-FSWs. The overall HIV, syphilis and HCV prevalence declined from 1.0%, 8.8% and 1.7% to 0.1%, 0.9% and 0.3%, respectively. There was no significant downward trend in the overall HIV and syphilis prevalence. However, HCV prevalence showed a decreasing trend among CL-FSWs. CM-FSWs had higher HIV prevalence (2.5% vs. 0.6%). Similarities and differences in STIs-related factors existed between CM-FSWs and CL-FSWs. For instance, receiving HIV-related services in the last year reduced the risk of HIV infection (for CM-FSWs: aOR = 0.234, 95% CI: 0.055-0.993; for CL-FSWs: aOR = 0.182, 95% CI: 0.058-0.567). Serving male clients at least 50 years old increased the risk of syphilis infection (for CM-FSWs: aOR = 4.277, 95% CI: 1.535-11.917; for CL-FSWs: aOR = 1.404, 95% CI: 1.087-1.815). Moreover, CM-FSWs with past-year STIs history had a higher risk of HIV (aOR = 34.976, 95% CI: 5.338-229.176) and HCV infection (aOR = 17.649, 95% CI: 1.846-168.846), both of which were associated with multiple factors in CL-FSWs. It is therefore necessary to develop effective, accessible, high-quality and targeted interventions for CM-FSWs and CL-FSWs.

Postharvest Calcium Chloride Treatment Strengthens Cell Wall Structure to Maintain Litchi Fruit Quality.

Litchi (Litchi chinensis Sonn.) fruit deterioration occurs rapidly after harvest and is characterized by pericarp browning, pulp softening, and decay. In this study, we found that calcium chloride (CaCl2) treatment (5 g L-1 CaCl2 solution vacuum infiltration for 5 min) affected the cell wall component contents and cell wall-degrading enzyme activities of litchi fruit during storage at room temperature. CaCl2 treatment significantly increased the contents of Ca2+ and cellulose, while it decreased the water-soluble pectin content, and the activities of polygalacturonase, ß-galactosidase, and cellulase in the litchi pericarp. Meanwhile, the treatment resulted in significantly increased contents of Ca2+, water-soluble pectin, ionic-soluble pectin, covalent-soluble pectin and hemicellulose, and upregulated activities of pectinesterase and ß-galactosidase, while significantly decreasing the activities of polygalacturonase and cellulase in litchi pulp. The above results indicate that CaCl2 treatment strengthened the cell wall structure of litchi fruit. More importantly, the enzymatic browning of the pericarp, softening of the pulp, and disease incidence were delayed. The treatment had a more pronounced effect on the pericarp than on the pulp. We consider CaCl2 treatment to be a safe and effective treatment for maintaining the postharvest quality of litchi fruit.

GA3 Treatment Delays the Deterioration of 'Shixia' Longan during the On-Tree Preservation and Room-Temperature Storage and Up-Regulates Antioxidants.

Gibberellic acids had been proven to improve the fruit quality and storability by delaying deterioration and maintaining the antioxidant system. In this study, the effect of GA3 spraying at different concentrations (10, 20, and 50 mg L-1) on the quality of on-tree preserved 'Shixia' longan was examined. Only 50 mg L-1 GA3 significantly delayed the decline of soluble solids (22.0% higher than the control) and resulted in higher total phenolics content (TPC), total flavonoid content (TFC), and phenylalanine ammonia-lyase activity in pulp at the later stages. The widely targeted metabolome analysis showed that the treatment reprogrammed secondary metabolites and up-regulated many tannins, phenolic acids, and lignans during the on-tree preservation. More importantly, the preharvest 50 mg L-1 GA3 spraying (at 85 and 95 days after flowering) led to significantly delayed pericarp browning and aril breakdown, as well as lower pericarp relative conductivity and mass loss at the later stages of room-temperature storage. The treatment also resulted in higher antioxidants in pulp (vitamin C, phenolics, and reduced glutathione) and pericarp (vitamin C, flavonoids, and phenolics). Therefore, preharvest 50 mg L-1 GA3 spraying is an effective method for maintaining the quality and up-regulating antioxidants of longan fruit during both on-tree preservation and room-temperature storage.

A Comprehensive Analysis of Physiologic and Hormone Basis for the Difference in Room-Temperature Storability between 'Shixia' and 'Luosanmu' Longan Fruits.

Although the effects of phytohormones (mainly salicylic acid) on the storability of longan fruit have been reported, the relationship between postharvest hormone variation and signal transduction and storability remains unexplored. The basis of physiology, biochemistry, hormone content and signalling for the storability difference at room-temperature between 'Shixia' and 'Luosanmu' longan fruit were examined. 'Luosanmu' longan exhibited faster pericarp browning, aril breakdown and rotting during storage. 'Luosanmu' pericarp exhibited higher malondialdehyde but faster decreased total phenolics, flavonoid, glutathione, vitamin C, catalase activity and gene expression. Higher H2O2 and malondialdehyde but lower glutathione, glutathione-reductase and peroxidase activities, while higher activities and gene expressions of polygalacturonase, ß-galactosidase and cellulose, lower covalent-soluble pectin, cellulose and hemicellulose but higher water-soluble pectin were observed in 'Luosanmu' aril. Lower abscisic acid and methyl jasmonate but higher expressions of LOX2, JAZ and NPR1 in pericarp, while higher abscisic acid, methyl jasmonate and salicylic acid together with higher expressions of ABF, JAZ, NPR1 and PR-1 in 'Luosanmu' aril were observed. In conclusion, the imbalance between the accumulation and scavenging of active oxygen in 'Luosanmu' longan might induce faster lipid peroxidation and senescence-related hormone signalling and further the polymerization of phenolics in pericarp and polysaccharide degradation in aril.

Prevalence trends and risk factors associated with HIV, syphilis, and hepatitis C virus among pregnant women in Southwest China, 2009-2018.

OBJECTIVE: This study investigated prevalence trends and identified the associated factors of HIV, syphilis and hepatitis C virus (HCV) among pregnant women in the Guangxi Zhuang Autonomous Region (Guangxi), Southwest China. METHODS: Serial cross-sectional surveys were performed annually among pregnant women in Guangxi from 2009 to 2018. Blood specimens were collected to test the prevalence of HIV, syphilis and HCV. Cochran-Armitage analysis was used to assess the trends of HIV, syphilis and HCV prevalence, as well as the sociodemographic and behavioural data. In this study, we used zero-inflated negative binomial (ZINB) regression models to identify factors associated with HIV, syphilis and HCV infection. RESULTS: A total of 23,879 pregnant women were included in the study. The prevalence of HIV, syphilis and HCV was 0.24%, 0.85% and 0.19%, respectively. There was a decrease in HIV prevalence from 0.54% to 0.10%, a decrease in HCV prevalence from 0.40% to 0.05% and a decrease in syphilis prevalence from 1.53% to 0.30%. The findings based on the ZINB model revealed that pregnant women who had a history of STI had significantly increased risks of HIV (OR 6.63; 95% CI 1.33-32.90) and syphilis (OR 9.06; 95% CI 3.85-21.30) infection, while pregnant women who were unmarried/widowed/divorced were more likely to have HIV (OR 2.81; 95% CI 1.20-6.54) and HCV (OR 58.12; 95% CI, 3.14-1076.99) infection. Furthermore, pregnant women whose husband had a history of STI (OR 5.62; 95% CI 1.24-25.38) or drug use (OR 7.36; 95% CI 1.25-43.43) showed an increased risk of HIV infection. CONCLUSIONS: There was a relatively low prevalence of HIV, syphilis and HCV among pregnant women. Although decreasing trends in HIV, syphilis and HCV infections were observed, effort is needed to promote STI testing in both premarital medical check-ups and antenatal care, especially targeting couples with a history of STI or drug use.

Trends and associated factors in the uptake of HIV testing among female sex workers in Sino-Vietnam border areas in Guangxi, China: a cross-sectional study.

BACKGROUND: HIV testing is a primary prevention strategy against the HIV epidemic and an entry point for HIV/AIDS-related care, prevention and treatment. This study aimed to estimate the uptake of HIV testing among Sino-Vietnam female sex workers (FSWs) in Guangxi, China, from 2016 to 2018, and to identify the factors influencing HIV testing uptake. METHODS: A cross-sectional survey was conducted among FSWs in two Sino-Vietnam border cities of Guangxi, China. The survey was conducted through face-to-face interview, the data were collected by a structured questionnaire, and HIV-1 infection was detected simultaneously. Logistic regression analysis was used to determine the factors associated with uptake of HIV testing. RESULTS: In total, 4565 Chinese local FSWs (CL-FSWs) and 636 cross-border migrant Vietnamese FSWs (CMV-FSWs) were recruited into this study. HIV-1 prevalence in CL-FSWs and CMV-FSWs was 0.70% and 3.14%, respectively. The rate of self-reported uptake of HIV testing in CL-FSWs and CMV-FSWs was 54.56% and 45.44%, respectively. The rates of self-reported uptake of HIV testing declined in both groups from 2016 to 2018. Logistic regression analysis indicated that a number of factors, including socio-demographic characteristics (age < 35 years, higher education, location in Chongzuo City), behaviour factors (having received free AIDS education, condom distribution services and peer education services, high risk sexual behaviours such as inconsistent condom use, having regular commercial sexual partners, etc.), psychological factors (perception of vulnerability to HIV/STIs, perception of risk for HIV infection) were the factors significantly related to uptake of HIV testing. CONCLUSION: In recent years, the rate of HIV testing uptake among Sino-Vietnam border FSWs in Guangxi, China was low, which may be an important reason for the high HIV-1 prevalence among FSWs in the region. A number of factors were identified to be associated with HIV-1 testing uptake, suggesting that HIV testing prevention strategies in this region could include accelerating AIDS education training, raising personal awareness of HIV testing, and improving accessibility of HIV testing.

Two divergent haplotypes from a highly heterozygous lychee genome suggest independent domestication events for early and late-maturing cultivars.

Lychee is an exotic tropical fruit with a distinct flavor. The genome of cultivar 'Feizixiao' was assembled into 15 pseudochromosomes, totaling ~470 Mb. High heterozygosity (2.27%) resulted in two complete haplotypic assemblies. A total of 13,517 allelic genes (42.4%) were differentially expressed in diverse tissues. Analyses of 72 resequenced lychee accessions revealed two independent domestication events. The extremely early maturing cultivars preferentially aligned to one haplotype were domesticated from a wild population in Yunnan, whereas the late-maturing cultivars that mapped mostly to the second haplotype were domesticated independently from a wild population in Hainan. Early maturing cultivars were probably developed in Guangdong via hybridization between extremely early maturing cultivar and late-maturing cultivar individuals. Variable deletions of a 3.7 kb region encompassed by a pair of CONSTANS-like genes probably regulate fruit maturation differences among lychee cultivars. These genomic resources provide insights into the natural history of lychee domestication and will accelerate the improvement of lychee and related crops.

Biological control agents colonize litchi fruit during storage and stimulate physiological responses to delay pericarp browning.

Introduction: Litchi is an economically important fruit in subtropical countries, but pericarp browning can limit its shelf life outside of controlled storage conditions. Effective and sustainable biological control strategies are needed to protect fruit against postharvest browning. Results and Discussion: In this study, we show that the four bacterial strains Bacillus licheniformis HS10, B. amyloliquefaciens LI24 and PP19, and Exiguobacterium acetylicum SI17 can delay fruit browning in both laboratory trials (LTs) and field plus laboratory trials (FLTs). Strains HS10, LI24, PP19 and SI17 showed 47.74%, 35.39%, 33.58% and 32.53% browning-inhibitory efficacy respectively at 180 h in LT. Litchi sarcocarp interior sourced isolate SI17 showed 74.05% inhibit-brown efficacy at 216 h in FLTs, performing better in FLT than in LT. Furthermore, strains PP19 and SI17 colonized the fruit pericarp and increased total phenolic and anthocyanin contents but decreased peroxidase and polyphenol oxidase activity. This is the first report of E. acetylicum (SI17) and B. licheniformis (HS10) strains acting as biological control agents (BCAs) to delay postharvest browning in litchi fruit. We conclude that PP19 and SI17 are promising BCAs against fruit browning, and their application could be effective for prolonging the shelf life of harvested litchi fruit.

Comparative metabolomics reveals differences in primary and secondary metabolites between "Shixia" and "Chuliang" longan (Dimocarpus longan Lour.) pulp.

Longan was a characteristic fruit for both medicine and food in China, which was rich in primary and secondary metabolites. Comprehensive high-throughput identification and comparison of metabolites in longan pulp among different varieties were still lacked. "Shixia" (SX) and "Chuliang" (CL) were the biggest major cultivars of longan in China. In this study, the content of total soluble solid, total flavonoid, and total phenolics indicated the difference of sweetness and bioactive compound content between the SX and CL pulp. Through a widely targeted metabolome, a total of 514 metabolites were identified and categorized into 23 groups mainly including flavonoids, amino acids & derivatives, lipids, phenolic acids, nucleotides & derivatives, alkaloids, organic acids and sugars & derivatives. A total of 89 metabolites with significantly differential accumulation (variable importance in projection (VIP) value ≧1, p-value <.05) over 1.2 fold were found between SX and CL, which were mainly enriched into pathways including flavone and flavonol biosynthesis, glycolysis/gluconeogenesis, and arginine and proline metabolism. Higher leveled hexose and hexose-phosphate (i.e., ß-D-glucose, D(+)-glucose, glucose-1-phosphate and glucose-6-phosphate), dominant organic acids (i.e., citric acid, succinic acid, D-malic acid, and citramalate), and essential amino acids (L-threonine, L-valine, L-isoleucine, L-leucine, L-phenylalanine and L-lysine) in SX pulp might be contributed to the taste and flavor difference between SX and CL. Moreover, the greatly differential accumulated secondary metabolites especially flavonoids and phenolic acids might result in different medicinal and nutritional characteristic between SX and CL. In conclusion, this study provided a systemic metabolic basis for understanding the nutritional differences between SX and CL and would help deepen the molecular biology and pharmacology research on characteristic metabolites in longan pulp.

Postharvest melatonin treatment inhibited longan (Dimocarpus longan Lour.) pericarp browning by increasing ROS scavenging ability and protecting cytomembrane integrity.

Postharvest melatonin treatments have been reported to improve the quality and storability, especially to inhibit browning in many fruits, but the effect had not been systematically investigated on longan fruit. In this study, the effect of 0.4 mM melatonin (MLT) dipping on the quality and pericarp browning of longan fruits stored at low temperature was investigated. The MLT treatment did not influence the TSS content of longan fruits but lead to increased lightness and h° value while decreased a* value of pericarp. More importantly, the treatment significantly delayed the increase in electrolyte leakage and malonaldehyde accumulation, inhibited the activities of polyphenol oxidase and peroxidase, and thus retarded pericarp browning. In addition, the treatment significantly inhibited the production of O2 •- and H2O2 while promoted the accumulation of glutathione, flavonoids, and phenolics at earlier storage stages in longan pericarp. Interestingly, the activities of ascorbate peroxidase (APX) and superoxide dismutase (SOD) were significantly upregulated but activities of catalase were downregulated in the MLT-treated longan pericarp. MLT treatment effectively enhanced APX and SOD activities, increased flavonoid, phenolics, and glutathione content, protected cytomembrane integrity, inhibited the production of O2 •- and H2O2 and browning-related enzymes, and thus delayed the longan pericarp browning.

Widely targeted metabolic analysis revealed the changed pigmentation and bioactive compounds in the ripening Berchemia floribunda (Wall.) Brongn. fruit.

Berchemia plants were important materials for Chinese traditional medicines due to their special secondary metabolites. Unlike the root, stem and leaf tissues, Berchemia floribunda (Wall.) Brongn. fruit was lacked of systematic metabolic investigation. Biochemical analysis found that the total flavonoid and total phenolic content of Berchemia fruit pulp showed a peak value at red ripe stage, and then decreased, but the total anthocyanin content sharply increased along with the coloration. By widely targeted metabolomic analysis, 644 metabolites were identified and categorized into 23 groups mainly including flavonoid, organic acids, amino acids, lipids, phenylpropanoid, nucleotides, alkaloids, carbohydrates, alcohols, anthocyanins & proanthocyanidins, vitamins, terpenes, polyphenols, phenolamides, quinones, indole derivatives, and sterides. Among them, 111 metabolites and 123 metabolites respectively showed up- and down-regulation from break stage to full mature. KEGG enrichment analysis indicated that active secondary metabolism such as biosynthesis of phenylpropanoids, flavonoid, and alkaloids happened during Berchemia fruit ripening. More importantly, Cyanidin-3-O-galactoside and other 3 cyanidins were found to be the predominant pigments in mature Berchemia fruit and increased cyanidins and pelargonidins but decreased anthocyanins might be contributed to the purple pigmentation of Berchemia fruit. Interestingly, 29 pharmaceutical compounds previously reported in other Berchemia tissues were also detected in ripening Berchemia fruit pulp: 8 flavonoid, 2 quinones & sucrose showed up-regulated accumulation while 6 polyphenols, 5 flavonoid, 3 phenylpropanoid, 2 organic acids, 1 quinones and ß-sitosterol showed down-regulated accumulation In conclusion, our first comprehensive metabolic fingerprint will promote the further study of B. floribunda fruit and its medical and food application.

Optimized precooling combined with SO2-released paper treatment improves the storability of longan (Dimocarpus longan Lour.) fruits stored at room temperature.

Precooling and sulfur dioxide fumigation were proved as effective methods for the preservation of longan (Dimocarpus longan Lour.) fruits. However, inadequate precooling and sulfur dioxide fumigation resulted in unexpected losses and short shelf life. A L9(34) orthogonal test was conducted to screen out ideal dosage of sodium metabisulfite (factor A), precooling method (factor B), and precooling duration (factor C) to improve the storability of longan fruit stored for 48 hr at room temperature (RT) (25℃). The overall qualities of all of the treated longan fruits after a 48-hr storage (OQST) and during the 5-day shelf at 25℃ (OQSF) were better than those of the control fruits. The treated fruits showed brighter fresh color (higher L*, b*, C*, and h° values but lower a* value), higher flavonoid, and chlorophyll contents. Moreover, the SO2 residue was concentrated in pericarp but little in aril for any of the 12 treatments. The multivariate variance analysis showed that factor A was dominant to determine both of the OQST and OQSF, while factor B affected the OQST, and factor C affected the OQSF. In total, "0.22% sodium metabisulfite + 4 hr precooling + uncovered precooling" was considered to be an ideal treatment. These results would contribute to improving longan postharvest preservation technology.

Analysis of metabolomics associated with quality differences between room-temperature- and low-temperature-stored litchi pulps.

Studies on how temperature affects the postharvest quality of litchi have focused mainly on pericarp browning but rarely on the metabolites in postharvest litchi pulp. In this study, the differences in respiration rates, total soluble solid content, and titratable acid content demonstrated that room and low temperatures have different effects on the quality of "Feizixiao" litchi pulp. UHPLC-ESI-QTOF-MS/MS analysis was performed to compare the differentially expressed metabolites (DEMs) in litchi pulp after 8 days of storage at room temperature (RT-8 d) with those in litchi pulp after 28 days of storage at low temperature (LT-28 d). Nineteen carbohydrates (phosphohexoses, sorbitol, and mannose), fifteen acids, seven amino acids, nine energy metabolites and nucleotides, and six aliphatic and secondary metabolites were identified as common DEMs in RT-8 d and LT-28 d pulps. These findings indicated active fructose and mannose metabolism and increased catabolism of nicotinate, nicotinamide, alanine, aspartate, and glutamate. Four carbohydrates (mainly phosphohexoses), five acids, ten amino acids, three aliphatic and secondary metabolites, and one hormone were identified as unique DEMs in RT-8 d pulp, the consumption of key metabolites in glycolysis and the tricarboxylic acid cycle, and accumulation of phenylalanine, tyrosine, and tryptophan. Active consumption of nucleotide metabolites and biosynthesis of aliphatics in LT-28 d pulp were indicated by unique DEMs (eleven carbohydrates, four acids, seven amino acids, seven energy metabolites and nucleotides, and six aliphatic and secondary metabolites). These results provided an unambiguous metabolic fingerprint, thereby revealing how room and low temperatures differentially influenced the quality of litchi pulp.

The effect of desulfurization on the postharvest quality and sulfite metabolism in pulp of sulfitated "Feizixiao" Litchi (Litchi chinensis Sonn.) fruits.

The residual sulfite caused by sulfur fumigation (SF) is a hazard to health and influenced the export trade of litchi. Desulfurization (DS) is a valid chemical method to reduce the residual sulfite. However, the effect of DS on fumigated litchi has not been studied at physiological and molecular level. This study was aimed to evaluate the effect of DS (SF plus 3% desulfurizer) on the postharvest quality, sulfite residue, and the sulfite metabolism in sulfitated "Feizixiao" litchi during the 4°C storage. Results indicated that the DS promoted the color recovery of sulfitated litchi and achieved an effect similar to SF on controlling rot and browning. DS recovered the water content and respiration rate of sulfitated litchi pericarp. Thus, DS improves commodity properties of sulfitated litchi. Moreover, DS greatly reduced sulfite residue especially in pulp and ensured the edible safety of sulfitated litchi. The activities of sulfite oxidase, sulfite reductase, serine acetyltransferase, and O-acetylserine(thiol) lyase in pulp increased after SF but fell down after DS while the expressions of their encoding genes decreased after SF but then rallied after DS. These results indicated the key role of these enzymes in sulfite metabolism after SF and DS changed the sulfite metabolism at both enzymatic and transcriptional level. It could be concluded that DS used in this study was an effective method for improving the color recovery and ensuring the edible safety of sulfitated litchi by not only chemical reaction but also both of enzymatic and transcriptional regulation.

The interaction of CpEBF1 with CpMADSs is involved in cell wall degradation during papaya fruit ripening.

Ethylene plays a pivotal role in climacteric fruit ripening; whereas 1-MCP, a non-toxic antagonist of ethylene, prevents ethylene-dependent responses and fruit ripening. In this study, a short-term treatment (1 h) with 400 nL L-1 1-MCP delayed the ripening of harvested papaya. However, long-term application of 1-MCP (400 nL L-1, 16 h) resulted in abnormal fruit ripening, with the fruits exhibiting normal yellowing without softening, significantly higher cellulose and lignin contents, and intact cell walls (CW). Furthermore, we found that long-term treatment with 1-MCP significantly inhibited the expression of CpEBF1, an EIN3-binding F-box-1 gene. A protein interaction analysis using yeast two-hybrid, BiFC and GST pull-down assays showed that CpEBF1 interacts with the CpMADS1/3 and CpEIL1 proteins. The interaction of CpEBF1 with CpMADS1/3 further activated the activities of CW-degradation gene promoters. Subcellular localization showed that these proteins were localized in the nucleus. Additionally, the expression levels of CpMADS1/3, CpEIL1, and several CW-degradation-related genes were significantly downregulated by long-term 1-MCP treatment. Therefore, we propose that the inhibited expression of CpEBF1 and CpMADS1/3 resulted in the repressed activation of CW-degradation-related genes via their interaction, thereby resulting in fruit softening disorders.

Preharvest zinc sulfate spray improves the storability of longan (Dimocarpus longan Lour.) fruits by protecting the cell wall components and antioxidants of pericarp.

BACKGROUND: Zinc (Zn) fertilization has been reported to improve the quality and storability of many fruits, but the mechanism had not been systematically studied. In this study, the effect of preharvest 0.2% zinc sulfate (ZnSO4 ) spray on the storability of longan fruits was investigated. RESULTS: The preharvest ZnSO4 spray did not significantly influence the quality but increased the Zn content in longan pericarp by 12.5-fold. More importantly, the treatment significantly reduced the rotting rate, pericarp browning, and aril breakdown of longan fruits stored at room temperature and low temperature. Physiological and biochemical results indicated that the treatment resulted in higher water retention capacity and inhibited the degradation of cellulose, pectin, flavonoid, and phenolics of longan pericarp at the late stages of storage. Consistent with these results, the activity of cellulase, polygalacturonase, polyphenol oxidase, and lipoxygenase was significantly inhibited in the ZnSO4 -treated longan pericarp at the late stages of storage. CONCLUSION: Higher Zn content in the ZnSO4 -treated longan pericarp might help to enhance the resistance against microbial infection, inhibit the hydrolysis of cell wall components, and thus effectively protected the cell wall components, maintained the cellular compartmentation, and prevented the phenolics and flavonoid from degradation by browning-related enzymes. © 2018 Society of Chemical Industry.