Isolation of ripening-related genes from ethylene/1-MCP treated papaya through RNA-seq.

BACKGROUND: Since papaya is a typical climacteric fruit, exogenous ethylene (ETH) applications can induce premature and quicker ripening, while 1-methylcyclopropene (1-MCP) slows down the ripening processes. Differential gene expression in ETH or 1-MCP-treated papaya fruits accounts for the ripening processes. To isolate the key ripening-related genes and better understand fruit ripening mechanisms, transcriptomes of ETH or 1-MCP-treated, and non-treated (Control Group, CG) papaya fruits were sequenced using Illumina Hiseq2500. RESULTS: A total of 18,648 (1-MCP), 19,093 (CG), and 15,321 (ETH) genes were detected, with the genes detected in the ETH-treatment being the least. This suggests that ETH may inhibit the expression of some genes. Based on the differential gene expression (DGE) and the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment, 53 fruit ripening-related genes were selected: 20 cell wall-related genes, 18 chlorophyll and carotenoid metabolism-related genes, four proteinases and their inhibitors, six plant hormone signal transduction pathway genes, four transcription factors, and one senescence-associated gene. Reverse transcription quantitative PCR (RT-qPCR) analyses confirmed the results of RNA-seq and verified that the expression pattern of six genes is consistent with the fruit senescence process. Based on the expression profiling of genes in carbohydrate metabolic process, chlorophyll metabolism pathway, and carotenoid metabolism pathway, the mechanism of pulp softening and coloration of papaya was deduced and discussed. We illustrate that papaya fruit softening is a complex process with significant cell wall hydrolases, such as pectinases, cellulases, and hemicellulases involved in the process. Exogenous ethylene accelerates the coloration of papaya changing from green to yellow. This is likely due to the inhibition of chlorophyll biosynthesis and the α-branch of carotenoid metabolism. Chy-b may play an important role in the yellow color of papaya fruit. CONCLUSIONS: Comparing the differential gene expression in ETH/1-MCP-treated papaya using RNA-seq is a sound approach to isolate ripening-related genes. The results of this study can improve our understanding of papaya fruit ripening molecular mechanism and reveal candidate fruit ripening-related genes for further research.

Effects of exercise therapy on knee joint function and synovial fluid cytokine levels in patients with knee osteoarthritis.

The aims of this study were to observe the effect of exercise therapy on the function of the knee joint and the levels of cytokines and cytokine-related genes, specifically tumor necrosis factor-α (TNF-α), high sensitivity C-reactive protein (hs-CRP) and matrix metalloproteinase-3 (MMP-3), in the synovial joints of patients with knee osteoarthritis (KOA) and to explore its mechanism of action. A total of 100 KOA patients were divided into a treatment group (n=50) and a control group (n=50) according to the order of admission. The patients in the treatment group were treated with diclofenac sodium combined with exercise therapy and the patients in the control group were treated with diclofenac sodium only. The function of the knee joint and the therapeutic efficacy was evaluated and the TNF-α, hs-CRP and MMP-3 levels in the synovial fluid were measured following 4 weeks of treatment. The results revealed that the knee joint index score and the TNF-α, hs-CRP and MMP-3 levels in the synovial fluid decreased significantly in the KOA patients of the two groups following treatment (P<0.05). Compared with the control group, the knee joint index score and the TNF-α, hs-CRP and MMP-3 levels in the synovial joints were lower and the therapeutic efficacy was increased in the patients of the treatment group (P<0.05). In brief, exercise therapy may decrease cytokine and cytokine-related gene levels in the synovial fluid and inhibit inflammatory factor-mediated cartilage degradation in KOA patients, thus, effectively improving the clinical symptoms of KOA.