四川王朗自然保护区大熊猫主食竹——缺苞箭竹(Fargesia denudat)不同发育时期酯酶和α-淀粉酶同工酶的研究

通过聚丙烯酰胺凝胶电泳,对生长在亚高山地带的大熊猫主食竹的实生苗、成竹和开花竹中不同发生年龄鞭系,以及同一鞭系内一系列生长年龄竹株作了酯酶、α-淀粉酶同工酶的比较研究。结果表明,同一竹种的不同发生年龄鞭系之间叶酯酶电泳类型存在明显差异,而同一鞭系内α-淀粉酶同工酶的变化表现与竹株生长年龄有关。由此认为,上述同工酶系统可以用作竹类无性系发育分析的生理指标。     

小麦芽依赖于DNA的RNA聚合酶Ⅱ不能转录绒毛烟斑驳病毒及其拟病毒

小麦芽经过匀浆、沉淀、高速及超速离心、透析以及DE_(52)离子交换层析等步骤,纯化小麦芽依赖于DNA的RNA聚合酶。用α-鹅膏蕈碱抑制试验,证明得到RNA聚合酶Ⅱ。用此聚合酶Ⅱ组建的体外转录体系的研究结果表明,绒毛烟斑驳病毒的拟病毒和卫星RNA(黄瓜花叶病毒相关RNA_3)都不能利用该体系进行转录,类病毒PSTV可进行转录,但转录效率明显低于小牛胸腺DNA;α-鹅膏簟碱可抑制类病毒的转录。绒毛烟斑驳病毒拟病毒和卫星RNA都不能被转录,表明他们的复制方法与类病毒不同。     

Enhanced cadmium cytotoxicity in A549 cells with reduced glutathione levels is due to neither enhanced cadmium accumulation nor reduced metallothionein synthesis

Glutathione (GSH) depletion sensitizes human lung carcinoma (A549-727) cells to the cytotoxic effects of Cd⁺⁺. The effects of GSH depletion on Cd⁺⁺ accumulation and Cd⁺-induced metallothionein (MT) content were investigated to determine the possible role of these Cd⁺⁺ responses in the sensitization process. Cellular GSH was depleted to 20% to 25% of control levels with buthionine sulfoximine (BSO), or diethyl maleate (DEM), respectively. Neither treatment significantly affected Cd⁺⁺-induced accumulation of exogenous³⁵s-cysteine into intracellular MT in a dose-dependent fashion. The results indicate that neither enhanced Cd⁺⁺ accumulation nor reduced MT synthesis plays a primary role in affecting enhanced Cd⁺⁺ cytotoxicity in A549 cells with reduced GSH levels. Although BSO inhibition of GSH synthesis enhanced MT synthesis, it sensitized the cells to Cd⁺⁺, which suggests an additive effect of GSH and MT in cadmium cytoprotection. This observation also raises the possibility that intracellular cysteine levels limit Cd⁺⁺-induced MT accumulation rates.Abbreviations GSH glutathione - MT metallothionein - BSO DL-buthionine-[S,R]-sulfoximine - DMSO dimethyl sulfoximine - DEM diethyl maleate - NP-40 nonidet-P40 - PBS phosphate buffered saline - HBSS Hank's balanced salt solution - DTT dithiothreitol 3. This work was presented in part at the 72nd Annual Meeting of the Federation of American Societies for Experimental Biology, Las Vegas, Nevada, May 1–5, 1988.     

Perinatal transmission of HIV-I in Zambia.

OBJECTIVE--To determine the occurrence of vertical transmission of HIV-I from women positive for the virus and the prognosis for their babies. DESIGN--Women presenting in labour were tested for HIV-I. Their newborn babies were also tested. Women positive for the virus were followed up with their babies for two years. SETTING--Teaching hospital in Lusaka, Zambia. SUBJECTS--1954 Women, of whom 227 were seropositive. Of 205 babies, 192 were positive for HIV-I. After birth 109 seropositive mothers and their babies and 40 seronegative mothers and their babies were available for follow up. MAIN OUTCOME MEASURES--Serological examination of mothers and their babies by western blotting. Birth weight and subsequent survival of babies. Women and babies were tested over two years for signs of seroconversion and symptoms of infection with HIV, AIDS related complex, and AIDS. RESULTS--Of the 109 babies born to seropositive mothers and available for follow up, 18 died before 8 months, 14 with clinical AIDS. Of the 91 remaining, 23 were seropositive at 8 months. By 24 months 23 of 86 surviving babies were seropositive, and a further five infected babies had died, four were terminally ill, 17 had AIDS related complex, and two had no symptoms. The overall rate of perinatal transmission was 42 out of 109 (39%). The overall mortality of infected children at 2 years was 19 out of 42 (44%). Before the age of 1 year infected children had pneumonia and recurrent coughs, thereafter symptoms included failure to thrive, recurrent diarrhoea and fever, pneumonia, candidiasis, and lymphodenopathy. All babies had received live attenuated vaccines before 8 months with no adverse affects. CONCLUSIONS--Vertical transmission from infected mothers to their babies is high in Zambia and prognosis is poor for the babies. Perinatal transmission and paediatric AIDS must be reduced, possibly by screening young women and counselling those positive for HIV-I against future pregnancy.     

Self-binding antibodies (autobodies) form specific complexes in solution

In this report we have shown that members of the murine self-binding antibody family, S107, form soluble complexes and precipitate under conditions in which non-self-binding antibodies remain in solution. Two approaches were used to demonstrate the self-association of autobodies: size-exclusion column chromatography and polyethylene glycol (PEG)-mediated precipitation assay. The anti-phosphorylcholine antibody T15 and two somatic variants, U4, which binds DNA, and U10, which has no identified specificity, produced larger precipitates in 10% PEG than other non-self-binding antibodies. The selectivity of PEG-mediated precipitation of self-binding antibodies is demonstrated by reduction of precipitation with specific haptens known to inhibit self-binding in solid-phase assays. Phosphorylcholine and nucleotides reduced precipitation of T15 and U4, respectively, but not U10. To rule out Fc-Fc mediated self-association in solution, we have also demonstrated self-complexing of F(ab')2 fragments of T15 using PEG. The self-binding locus was further dissected using peptides derived from V regions. A 24-residue peptide derived from the second hypervariable region of the VH of S107 specifically enhanced precipitation of T15, U4, and U10, but not other antibodies. These results provide evidence of a dormant potential of self-binding antibodies to precipitate under conditions that reduce the solubility of proteins. The implication of this potential is discussed with respect to pathological complex formation.     

Tumor idiotype vaccines. VII. Analysis and correlation of structural, idiotypic, and biologic properties of protective and nonprotective Ab2

We have previously generated and used anti-Id mAb (Ab2) to induce protective immunity against the L1210 DBA/2 tumor and for immunotherapy of established tumors. Among various anti-Id that were typed serologically as internal image Ab2 of the mouse mammary tumor virus tumor-associated Ag gp52, only one induced protective immunity and was effective in immunotherapy. In this study we compared the structural, idiotypic, and network properties of the protective and nonprotective antiidiotypic antibodies. The DNA sequence of the variable regions of six anti-Id was determined. The VH sequence of four Ab2, including the protective Ab2, are highly homologous, whereas the VL sequences differ and were assigned to different Vk families. In addition, the DH sequence region of the same four Ab2 are identical, whereas one is highly homologous and another one without homology. Search for amino acid sequence homologies between the Ab2 and gp52 showed the strongest similarities in the CDR2 of the L chain from the protective Ab2. In addition, the CDR2 region also had homology with a T cell epitope on gp52. The biologic basis of effective idiotypic mimicry was studied at the level of Ab3 induced by the Ab2. Id inhibition analysis using Ab3 induced by either protective or nonprotective Ab2, revealed differences. Thus, there is evidence for differences among the Ab1-Ab2-Ab3 cascade induced by protective and nonprotective anti-Id.