【目的】通过对果实质地差异明显的2个梨品种进行质地差异相关研究,旨在发现导致梨品种果实质地差异的关键因素,为优良梨品种的选育提供理论依据。【方法】以玉露香梨和大果水晶梨为试材,观察发育过程中果肉细胞超显微结构,测定果实的...【目的】通过对果实质地差异明显的2个梨品种进行质地差异相关研究,旨在发现导致梨品种果实质地差异的关键因素,为优良梨品种的选育提供理论依据。【方法】以玉露香梨和大果水晶梨为试材,观察发育过程中果肉细胞超显微结构,测定果实的硬度、脆度值、细胞壁代谢相关酶的活性和相关基因的相对表达量,并进行相关性分析。【结果】①果实生长发育过程中玉露香梨和大果水晶梨果实硬度逐渐下降,且花后60 d 2个梨品种脆度值逐渐下降,玉露香梨果实硬度和脆度值显著低于大果水晶梨。②在400×放大显微倍数下,幼果期玉露香梨果肉细胞比大果水晶梨的大;果实膨大期和成熟期,2个梨品种果肉细胞均明显增大,玉露香梨果肉细胞小于大果水晶梨;玉露香梨细胞断裂边缘整齐平滑,形成脆性断口,大果水晶梨断裂边缘粗糙而不整齐。③果实发育过程中玉露香梨果肉果胶甲酯酶(Pectin methylesterase,PME)活性极显著低于大果水晶梨,而多聚半乳糖醛酸酶(Polygalacturonase,PG)活性和β-半乳糖苷酶(β-Galactosidase,β-Gal)活性极显著高于大果水晶梨。④果实发育过程中玉露香梨果肉PME基因、PG基因和β-Gal基因相对表达量极显著低于大果水晶梨的表达量。相关性分析表明,玉露香梨和大果水晶梨的硬度与β-Gal基因相对表达量呈显著正相关,脆度值与PG基因相对表达量呈显著正相关。【结论】随着果实生长发育,玉露香梨和大果水晶梨果实质地的差异不仅表现在果肉细胞超显微结构上,还与细胞壁代谢相关酶密切相关,PG基因和β-Gal基因可能在玉露香梨和大果水晶梨质地变化中发挥关键作用。展开更多
To identify the metabolite and CYP450 isoforms involved in rat liver microsomal metabolism of TM208. The present study investigated the metabolism of TM208 and the effects of selective CYP450 inhibitors on the metabol...To identify the metabolite and CYP450 isoforms involved in rat liver microsomal metabolism of TM208. The present study investigated the metabolism of TM208 and the effects of selective CYP450 inhibitors on the metabolism of TM208 in rat liver microsomes. Various specific inhibitors of CYP were used to identify the isoforms of CYP involved in the metabolism of TM208. The inhibitor of CYP2D and that of CYP2B had strong inhibitory effects on TM208 metabolism in a concentration-de- pendant manner, the inhibitor of CYP1A had a modest inhibitory effect, and the inhibitor of CYP3A seemed not to have an obvious inhibitory effect on TM208 metabolism. TM208 might mainly be metabolized by CYP2D and CYP2B in rat liver microsomes.展开更多
Hepatitis B virus X protein （HBx） plays a crucial role in the development of hepatocellular carcinoma. Here, we sought to identify the mechanisms by which HBx mediates liver cell proliferation. We found that HBx upr...Hepatitis B virus X protein （HBx） plays a crucial role in the development of hepatocellular carcinoma. Here, we sought to identify the mechanisms by which HBx mediates liver cell proliferation. We found that HBx upregulated the levels of cyclooxygenase-2 （COX-2）, 5-1ipoxygenase （5-LOX） and phosphorylated extracellular signal-regulated protein kinases 1/2 （p-ERK1/2） in liver cells. HBx-induced p-ERK1/2 was abolished by inhibition of Gi/o proteins, COX or LOX. In addition, HBx increased the amounts of prostaglandin E2 （PGE2） and leukotriene B4 （LTB4） released from cell lines derived from hepatocytes. Moreover, these released arachidonic acid metabolites were able to activate ERK1/2. Interestingly, activated ERK1/2 could upregulate the expression of COX-2 and 5-LOX in a positive feedback manner. In conclusion, HBx enhances and maintains liver cell proliferation via a positive feedback loop involving COX-2, 5-LOX, released arachidonic acid metabolites, Gi/o proteins and p-ERK1/2.展开更多
文摘【目的】通过对果实质地差异明显的2个梨品种进行质地差异相关研究,旨在发现导致梨品种果实质地差异的关键因素,为优良梨品种的选育提供理论依据。【方法】以玉露香梨和大果水晶梨为试材,观察发育过程中果肉细胞超显微结构,测定果实的硬度、脆度值、细胞壁代谢相关酶的活性和相关基因的相对表达量,并进行相关性分析。【结果】①果实生长发育过程中玉露香梨和大果水晶梨果实硬度逐渐下降,且花后60 d 2个梨品种脆度值逐渐下降,玉露香梨果实硬度和脆度值显著低于大果水晶梨。②在400×放大显微倍数下,幼果期玉露香梨果肉细胞比大果水晶梨的大;果实膨大期和成熟期,2个梨品种果肉细胞均明显增大,玉露香梨果肉细胞小于大果水晶梨;玉露香梨细胞断裂边缘整齐平滑,形成脆性断口,大果水晶梨断裂边缘粗糙而不整齐。③果实发育过程中玉露香梨果肉果胶甲酯酶(Pectin methylesterase,PME)活性极显著低于大果水晶梨,而多聚半乳糖醛酸酶(Polygalacturonase,PG)活性和β-半乳糖苷酶(β-Galactosidase,β-Gal)活性极显著高于大果水晶梨。④果实发育过程中玉露香梨果肉PME基因、PG基因和β-Gal基因相对表达量极显著低于大果水晶梨的表达量。相关性分析表明,玉露香梨和大果水晶梨的硬度与β-Gal基因相对表达量呈显著正相关,脆度值与PG基因相对表达量呈显著正相关。【结论】随着果实生长发育,玉露香梨和大果水晶梨果实质地的差异不仅表现在果肉细胞超显微结构上,还与细胞壁代谢相关酶密切相关,PG基因和β-Gal基因可能在玉露香梨和大果水晶梨质地变化中发挥关键作用。
基金National Basic Research Program of China (863 Program,Grant No.2004AA2Z3783)National Natural Science Foundation of China (Grant No.20672009)
文摘To identify the metabolite and CYP450 isoforms involved in rat liver microsomal metabolism of TM208. The present study investigated the metabolism of TM208 and the effects of selective CYP450 inhibitors on the metabolism of TM208 in rat liver microsomes. Various specific inhibitors of CYP were used to identify the isoforms of CYP involved in the metabolism of TM208. The inhibitor of CYP2D and that of CYP2B had strong inhibitory effects on TM208 metabolism in a concentration-de- pendant manner, the inhibitor of CYP1A had a modest inhibitory effect, and the inhibitor of CYP3A seemed not to have an obvious inhibitory effect on TM208 metabolism. TM208 might mainly be metabolized by CYP2D and CYP2B in rat liver microsomes.
文摘Hepatitis B virus X protein （HBx） plays a crucial role in the development of hepatocellular carcinoma. Here, we sought to identify the mechanisms by which HBx mediates liver cell proliferation. We found that HBx upregulated the levels of cyclooxygenase-2 （COX-2）, 5-1ipoxygenase （5-LOX） and phosphorylated extracellular signal-regulated protein kinases 1/2 （p-ERK1/2） in liver cells. HBx-induced p-ERK1/2 was abolished by inhibition of Gi/o proteins, COX or LOX. In addition, HBx increased the amounts of prostaglandin E2 （PGE2） and leukotriene B4 （LTB4） released from cell lines derived from hepatocytes. Moreover, these released arachidonic acid metabolites were able to activate ERK1/2. Interestingly, activated ERK1/2 could upregulate the expression of COX-2 and 5-LOX in a positive feedback manner. In conclusion, HBx enhances and maintains liver cell proliferation via a positive feedback loop involving COX-2, 5-LOX, released arachidonic acid metabolites, Gi/o proteins and p-ERK1/2.
