人干扰素α2b和IgGFc片段融合蛋白显著延长体内半衰期

重组人干扰素a(rHuIFNa)已被广泛用于临床治疗多种人类病毒性疾病和肿瘤。但IFNa在体内半衰期较短从而导致IFNa在用药后数小时即从血浆中被清除。目前常用化学修饰和构建融合蛋白的方法来延长IFNa的半衰期。在本研究中,构建了IFNa2b与人IgG免疫球蛋白Fc片段的融合基因(IFNa2b-Fcγ)并在毕赤酵母中以二聚体形式分泌表达,并有部分糖基化。不同亚型Fcγ片段的融合蛋白对IFNa2b抗病毒活性均有一定影响。其中IFNa2b-Fcγ2所受影响最小,较单纯的IFNa2b降低了2.3倍,抗病毒活性可达4.29x10^7 IU/mg,大鼠皮下注射后循环血液中半衰期达65 h,血液中存留时间120 h以上,比商品重组干扰素的体内半衰期延长约8倍,血液存留时间延长10倍,显示了其良好的临床应用前景。

实时荧光定量分析SK-N-SH细胞中β-actin mRNA的半衰期

目的:探讨和分析SK-N-SH细胞中β-actinmRNA的半衰期。方法:建立包含β-actin基因片断的pMD-T载体的梯度稀释曲线,应用VIC标记的Taqman-MGB探针进行检测,用Opticon2.02软件分析结果。以不同浓度和不同时间的放线菌素D阻断SK-N-SH细胞转录,提取总RNA并予荧光定量RT-PCR检测β-actinmRNA。结果:SK-N-SH细胞中β-actinmRNA的半衰期为4h。与未处理组相比,4h组β-actin的拷贝数差异有显著性(P<0.05),12h和24h组β-actin拷贝数差异有极显著性(P<0.01)。不同浓度之间放线菌素D对β-actin拷贝数的影响差异不大(P>0.05)。结论:应用实时荧光定量RT-PCR,通过比较mRNA与总RNA的拷贝数,建立了一种准确方便地检测mRNA衰减的方法。同时β-actin不适合做放线菌素D处理实验中的内参照。

A Simulation Study on Effect of Surface Film-Forming Material on Water Evaporation

A greenhouse experiment was conducted to investigate the effect of surface film-forming material (SFFM), a mixture of 16-18-octadecanols by emulsification, on water evaporation. Air-dried soil with distilled water was incubated firstly for 7 days to reestablish soil biological activity and then for another 7 days after treated with SFFM at rates of 0, 1, 2, 4, 6 and 8 g m-2, respectively. Everyday during the 7-day incubation after addition of SFFM, water losses due to evaporation were ~measured by an electronic balance. The rate of water evaporation with the addition of SFFM was reduced significantly compared with the control treatment and the effectiveness of SFFM on water evaporation reduced with time. According to the equation expressions of the effect of SFFM on water evaporation, the half-life of electiveness of SFFM on water evaporation was introduced and calculated to analyze quantitative relationship between the effectiveness of SFFM on water evaporation and the addition rate of SFFM. The calculated half-life increased with the addition rate of SFFM and the confidence of the calculated values of the half-life was high, suggesting that the half-life of effectiveness of SFFM on water evaporation could be described quantitatively and may be helpful for ameliorating application method of SFFM and screening surface-film forming materials in order to improve nitrogen fertilizer use efficiency in flooded rice fields.

Cloning and expression of follistatin gene in half-smooth tongue sole Cynoglossus semilaevis during the reproduction cycle

Follistatin(FST) is a monomeric glycoprotein highly enriched in cysteines and belongs to TGF-β superfamily. FST can suppress the secretion of follicle-stimulating hormone and plays a vital role in the reproduction of vertebrates. We used rapid amplification of cDNA ends technology to clone the FST gene of half-smooth tongue sole,Cynoglossus semilaevis. We characterized its phylogenetic context and expression patterns to elucidate its function in the breeding season. The full-length sequence of FST is 1 455 bp and encodes a protein of 321 amino acids. We investigated the expression pattern of FST in C. semilaevis at different stages of reproduction using reverse transcription-polymerase chain reaction(RTPCR). FST m RNA was expressed in all 13 tissues analyzed,and was expressed at high levels in gonad and at slightly lower levels in gill and brain. During the reproductive cycle of C. semilaevis,the transcript level of FST was the highest in the perinucleolus stage,decreased in the primary yolk stage,slightly increased in the tertiary yolk stage,and then reduced to a minimal level in the atretic follicles stage of the ovary. We concluded that FST suppressed follicle-stimulating hormone,which stimulated oocyte development. However,no significant variation was observed across all stages of testis development,although the expression level in the spermatogenesis stage was relatively low,which may result from the regulation of FST by aromatase.

Dynamic change of xylanase activity and gene expression during wheat germination on As（III） stress

Through water cultivating method, the dynamic changes of xylanase activity in seed, root and plumule of wheat with different As （III） concentration treatment were studied. The results indicated that the order of average xylanase activity was seed〉plumule〉root. With the increasing concentration of As （III）, the xylanase activity elevated first then dropped in seed, but it descended first then ascended in root and plumule. As the sampling time prolonged, the xylanase activity of seeds climbed first then dropped on the four as （III） concentration, the same trend also appeared in pulume, as the as （Ill） concentration went up, the xylanase activity moved up simultaneity. Semi-quantity Reverse Transcription Polymerase Chain Reaction was used in the study, the results indicated that, the xylanase gene began to express at 132 h on 0 mg/L As （III） concentration and at 120h on other concentration in the leaves of wheat.