Morusin induces apoptosis and suppresses NF-kappaB activity in human colorectal cancer HT-29 cells

Morusin is a pure compound isolated from root bark of Morusaustralis (Moraceae). In this study, we demonstrated that morusin significantly inhibited the growth and clonogenicity of human colorectal cancer HT-29 cells. Apoptosis induced by morusin was characterized by accumulation of cells at the sub-G₁ phase, fragmentation of DNA, and condensation of chromatin. Morusin also inhibited the phosphorylation of IKK-α, IKK-β and IκB-α, increased expression of IκB-α, and suppressed nuclear translocation of NF-κB and its DNA binding activity. Dephosphorylation of NF-κB upstream regulators PI3K, Akt and PDK1 was also displayed. In addition, activation of caspase-8, change of mitochondrial membrane potential, release of cytochrome c and Smac/DIABLO, and activation of caspase-9 and -3 were observed at the early time point. Downregulation in the expression of Ku70 and XIAP was exhibited afterward. Caspase-8 or wide-ranging caspase inhibitor suppressed morusin-induced apoptosis. Therefore, the antitumor mechanism of morusin in HT-29 cells may be via activation of caspases and inhibition of NF-κB.     

Selective modulation of band 4.1 binding to erythrocyte membranes by protein kinase C

We have studied the effects of band 4.1 phosphorylation on its association with red cell inside-out vesicles stripped of all peripheral proteins. Band 4.1 bound to these vesicles in a saturable manner, and binding was characterized by a linear Scatchard plot with an apparent Kd of 1-2 x 10(-7) M. Phosphorylation of band 4.1 by purified protein kinase C reduced its ability to bind to membranes, resulting in a reduction in the apparent binding capacity of the membrane by 60-70% but little or no change in the apparent Kd of binding. By contrast, phosphorylation of band 4.1 by cAMP-dependent kinase had no effect on membrane binding. Digestion of the stripped inside-out vesicles with trypsin cleaved 100% of the cytoplasmic domain of band 3 but had little or no effect on glycophorin. Binding of band 4.1 to these digested vesicles was reduced by 70%. Phosphorylation of band 4.1 by protein kinase C had no effect on its binding to the digested vesicles, suggesting that the cytoplasmic domain of band 3 contained the phosphorylation-sensitive binding sites. This was confirmed by direct measurement of band 4.1 binding to the purified cytoplasmic domain of band 3. Phosphorylation of band 4.1 by protein kinase C reduced its binding to the purified 43-kDa domain by as much as 90%, while phosphorylation by cAMP-dependent kinase was without effect. These results show a selective effect of protein kinase C phosphorylation on the binding of band 4.1 to one of its membrane receptors, band 3, and suggest a mechanism whereby one of the key red cell-skeletal membrane associations may be modulated.     

~（60）Co－γ射线诱变柠檬酸产生菌黑曲霉Co9－6的研究

本试验采用￣（６０）Ｃｏ－γ射线对柠檬酸产生菌黑曲霉Ｃｏ９－６进行辐射,经两次处理后选育出Ｌ１２１７和Ｌ８０１两株优良柠檬酸产生菌。中试结果表明菌株Ｌ１２１７较Ｌ８０１更优：产酸率较菌株Ｃｏ９－６提高１７．６％、发酵周期缩短１３．４％、对糖转化率提高１３．３％。     

Detection and Quantification of Fusarium oxysporum f. sp. niveum Race 1 in Plants and Soil by Real-time PCR

Fusarium wilt caused by Fusarium oxysporum f. sp. niveum (Fon) is the most serious soil-borne disease in the world and has become the main limiting factor of watermelon production. Reliable and quick detection and quantification of Fon are essential in the early stages of infection for control of watermelon Fusarium wilt. Traditional detection and identification tests are laborious and cannot efficiently quantify Fon isolates. In this work, a real-time polymerase chain reaction (PCR) assay has been described to accurately identify and quantify Fon in watermelon plants and soil. The FONRT-18 specific primer set which was designed based on identified specific sequence amplified a specific 172 bp band from Fon and no amplification from the other formae speciales of Fusarium oxysporum tested. The detection limits with primers were 1.26 pg/μl genomic DNA of Fon, 0.2 pg/ng total plant DNA in inoculated plant, and 50 conidia/g soil. The PCR assay could also evaluate the relationships between the disease index and Fon DNA quantity in watermelon plants and soil. The assay was further used to estimate the Fon content in soil after disinfection with CaCN₂. The real-time PCR method is rapid, accurate and reliable for monitoring and quantification analysis of Fon in watermelon plants and soil. It can be applied to the study of disease diagnosis, plant-pathogen interactions, and effective management.     

Transport functions and expression analysis of vacuolar membrane aquaporins in response to various stresses in rice

The vacuole, a multifunctional organelle of most plant cells, has very important roles in space filling, osmotic adjustment, storage and digestion. Previous researches suggested that aquaporins in the tonoplast were involved in vacuolar functions. The rice genome contains 33 aquaporin genes, 10 of which encode tonoplast intrinsic proteins (TIPs). However, the function of each individual TIP isoform and the integrated function of TIPs under various physiological conditions remain elusive. Here, five rice TIP members were characterized with water and/or glycerol transport activities using the Xenopus oocyte expression system. OsTIP1;2, OsTIP2;2, OsTIP4;1 and OsTIP5;1 possessed water transport activity. OsTIP1;2, OsTIP3;2 and OsTIP4;1 were demonstrated with glycerol transport activity. Rice TIP expression patterns under various abiotic stress conditions including dehydration, high salinity, abscisic acid (ABA) and during seed germination were investigated by real-time PCR. OsTIP1s (OsTIP1;1 and OsTIP1;2) were highly expressed during seed germination, whereas OsTIP3s (OsTIP3;1 and OsTIP3;2) were specifically expressed in mature seeds with a decrease in expression levels upon germination. The results of this research provided a functional and expression profiles of rice TIPs.