Molecular cloning of the cDNA for the catalytic subunit of human DNA polymerase delta.

The cDNA of human DNA polymerase delta was cloned. The cDNA had a length of 3.5 kb and encoded a protein of 1107 amino acid residues with a calculated molecular mass of 124 kDa. Northern blot analysis showed that the cDNA hybridized to a mRNA of 3.4 kb. Monoclonal and polyclonal antibodies to the C-terminal 20 residues specifically immunoblotted the human pol delta catalytic polypeptide. A multiple sequence alignment was constructed. This showed that human pol delta is closely related to yeast pol delta and the herpes virus DNA polymerases. The levels of pol delta message were found to be induced concomitantly with DNA pol delta activity and DNA synthesis in serum restimulated proliferating IMR90 cultured cells. The human pol delta gene was localized to chromosome 19 by Southern blotting of EcoRI digested DNA from a panel of rodent/human cell hybrids.     

降香黄檀着叶期和无叶期次生韧皮部筛分子的超微结构

利用透射电镜技术研究了生长在海南岛的热带落叶树降香黄檀(Dalbegia odorifera T.Chen)1—2年生枝条着叶期和无叶期次生韧皮部筛分子的超微结构,并就这两个时期的筛分子进行了比较。着叶期每个成熟筛分子内有一个带尾的纺锤形P-蛋白质体,主体由稠密而散乱的P-蛋白质细纤维组成,尾部呈结晶状;筛分子具有横向端壁和单筛板,在邻近筛板处,细胞壁向筛分子腔内形成明显的突起。无叶期仍然保持着与着叶期大致相同厚度的有功能韧皮部,筛分子具有正常的原生质体,P-蛋白质和筛板孔的结构也与着叶期的相同,但筛分子内有较多的淀粉粒和囊泡。     

The 32-kilodalton envelope protein of vaccinia virus synthesized in Escherichia coli binds with specificity to cell surfaces.

The nature of interaction between vaccinia virus and the surface of host cells as the first step in virus infection is undefined. A 32-kDa virus envelope protein has been identified as a cell surface binding protein (J.-S. Maa, J. F. Rodriguez, and M. Esteban, J. Biol. Chem. 265:1569-1577, 1990). To carry out studies on the structure-function relationship of this protein, the 32-kDa protein was obtained from Escherichia coli cells harboring the expression plasmid pT7Ek32. The recombinant polypeptide was found to have structural properties similar to those of the native virus envelope protein. Binding studies of 125I-labeled 32-kDa protein to cultured cells of various origins revealed that the E. coli-produced 32-kDa protein exhibited selectivity, specificity, and saturability. Scatchard analysis indicated about 4.5 x 10(4) sites per cell with a high affinity (Kd = 1.8 x 10(-9) M), suggesting interaction of the 32-kDa protein with a specific receptor. The availability of large quantities of the 32-kDa virus protein in bacteria will permit further structural and functional studies of this virus envelope protein and facilitate identification of the specific cell surface receptor.     

Changes in pulmonary Cu−Zn contents in superior mesenteric artery occlusion shock of rabbit

Contents of Cu and Zn of into-pulmonary blood (IPB), out-pulmonary blood (OPB), Lung tissue, and supernatant and macrophages of Lung Lavage were determined in superior mesenteric artery occlusion (SMAO) shock of rabbits. Zn of pulmonary tissue was 11.42 +/- 0.60 and 14.52 +/- 1.78 (micrograms/g wet wt) in SMAO shock and control groups, respectively. Content of Zn was found to be lower, Cu was not changed, and Cu/Zn ratio increased in lung tissue in SMAO shock. Contents of Cu and Zn in other samples were not changed. The results suggest that lower Zn in lung tissue related to acute lung injury.     

用2DNMR鉴定倍半萜多元酯的结构

利用2DNMR结合其他波谱方法从苦皮藤种子油中鉴定了2个新倍半萜多元酯,它们分别是1α-苯甲酰氧-8β-烟酰氧-9α、11β-2乙酰氧-β-二氢沉香呋喃,1β-苯甲酰氧-2α、8β、9α、11β-4乙酰氧-β-二氢沉香呋喃,命名为苦皮藤酯2和3。     

Thyroid hormone down-regulates p55, a thyroid hormone-binding protein that is homologous to protein disulfide isomerase and the beta-subunit of prolyl-4-hydroxylase

We have previously characterized a cellular thyroid hormone-binding protein (p55) that is found concentrated on the lumenal face of the endoplasmic reticulum and nuclear envelope (Cheng, S.-y., Hasumura, S., Willingham, M.C., and Pastan, I. (1986) Proc. Natl. Acad. Sci. U.S.A. 83, 947-951). To understand the role p55 plays in thyroid hormone action, we examined the regulation of p55 by 3,3',5-triiodo-L-thyronine (T3). Rat pituitary tumor GH3 cells cultured in regular medium, thyroid hormone-depleted medium (Td medium), or Td medium supplemented with 50 nM T3 (Td + T3 medium) were metabolically labeled with [35S]methionine and immunoprecipitated with antibodies against p55. Treatment with T3 caused a fall in p55 levels. Poly(A+) RNA from cells cultured in regular, Td, or Td + T3 medium was hybridized to a cDNA from p55. T3 withdrawal or addition had no effect on p55 mRNA levels. Furthermore, the initial rates of synthesis of p55 from cells cultured in regular, Td, and Td + T3 were found to be similar. However, analysis of the decay curves from cells in which p55 was pulse-labeled with [35S]methionine indicated that p55 is 2-fold less stable in T3 containing medium. These results indicated that down-regulation of p55 by T3 occurs at the post-translational level. Since DNA sequence analysis indicates that p55 is identical to protein disulfide isomerase and the beta-subunit of prolyl-4-hydroxylase, T3 may mediate its effects on the synthesis, secretion, and/or transport of proteins via p55.     

Treatment of leachate from a solid waste landfill site using a two-stage anaerobic filter

Raw leachate was treated using a two-stage upflow anaerobic filter process. Leachate from a solid waste landfill site, which received both municipal and industrial wastes, contained high organic matter (17-21 g/L COD, 13-14 g/L BOD, and 3.5-4.6 g/L volatile acids), and low metal (Zn and Fe) concentrations. Depending on sampling time, leachate composition and characteristics varied considerably. At an organic loading up to 4 g COD/day(2) media area, the BOD and COD removal percentages were 98 and 91%, respectively. The biofilters were also effective for metal removal. However, the filter effluent contained a high concentration of ammonia. System overloading was characterized by the accumulation of large quantities of volatile acids and by a now ratio of alkalinity/volatile acids, resulting in low COD removal and reduced gas production. Once the first filter was upset, the second stage could only partially respond to the volatile acids accumulated in the effluent of first filter.     

甜菜坏死黄脉病毒的分离提纯及其生物化学特性的研究

本研究工作中,建立了一个有效的甜菜坏死黄脉病毒的分离提纯程序,解决了该病毒粒体易于聚集难以提纯的问题,其操作要点是,(1)通过Sepharose 2B柱层析代替超离心,有效地除去一些小分子量核酸杂质;(2)经PEG再次沉淀浓缩后,调整pH至酸牲(pH3.0),使病毒充分悬浮以减少凝聚;(3)在病毒等电点(pH4.8～4.9)条件下,进一步沉淀以纯化病毒。根据病毒提取物的OD260/OD280比值,算出核酸含量约4.5％。核酸电泳出现4条带,分子量分别为:2.25×10~(?),1.8×10~(?),1.05×10~(?),0.75×10~(?)道尔顿。病毒提取物经超速离心出现4个界面,沉淀系数分别为,200.8S,165S,125.8S,100S。说明甜菜坏死黄脉病毒可能是4组分病毒粒体。病毒粒体含一蛋白亚基,分子量约为2.05±0.05×10~4道尔顿,由16种共199个氨基酸组成。