黄瓜子叶扩张与细胞分裂素的关系

BA(benzyl adenine)专一性地促进离体黄瓜子叶的扩张。为了研究 BA 的作用机理,我们采用间接 EIISA 和 HPLC 的方法测定了子叶扩张过程中内源玉米素(Z)和玉米素核苷(ZR)含量的变化。离体黄瓜(Cucumis sativus,津研4号)子叶用10mg/l 的 BA 培养,72小时之后,处理子叶鲜重的增加比对照高70%。Z+ZR 在 BA 处理的子叶中有大量的积累。结果表明 BA 可能诱发了黄瓜子叶中的细胞分裂素生物合成和代谢的某些基因。     

细胞分裂素在离体蒜苔内的运转

离体蒜苔饲喂带~3H 标记的6-苄基腺嘌呤(BA)后在暗中25℃下放置,分别在第3、5、10、15、20天取样,进行放射性物质的分布分析。结果表明:(1)BA 能沿着苔茎大量、长距离地上运,并在顶端的珠蒜中积累;(2)BA 的这种运转具有很强的向顶极性;(3)这种运转是一个平缓而稳定的过程,珠蒜中 BA 的积累与时间成较好的线性关系;(4)顶端的珠蒜对 BA 的上运是必不可少的。根据以上结果,本文对蒜苔内 BA 的运转机理及意义进行了讨论。     

Development of acute thermotolerance in L929 cells: lack of HSP28 synthesis and phosphorylation.

We investigated the correlation between the development of acute thermotolerance and the phosphorylation, synthesis, and expression of the HSP28 family in murine L929 cells. Following heating at 43 degrees C for 30 min, thermotolerance developed rapidly in exponential-phase cells and reached its maximum 4-9 h after heat shock. Maximal thermal resistance was maintained for 24 h and then gradually decayed. However, heat-induced phosphorylation of HSP28 was not detected. Furthermore, HSP28 synthesis during incubation at 37 degrees C for 12 h following heat shock was not detected by [3H]-leucine labeling followed by two-dimensional polyacrylamide gel electrophoresis. In addition, Northern blots failed to demonstrate expression of the HSP28 gene. Unlike HSP28, the expression of constitutive and inducible HSP70 genes, along with the synthesis of their proteins, was observed during incubation at 37 degrees C after heat shock. These results demonstrate that HSP28 synthesis and its phosphorylation are not required to develop acute thermotolerance in L929 cells.     

Dasymaschalon tibetense (Annonaceae): a new species from China

A new species, Dasymaschalon tibetense, has been described from South Tibet, China. The species is related to D. rostratum, but can be easily distinguished by its rounded apex of fruitlets and its 7.7–9.5 cm long petals.     

真菌诱导子对悬浮培养西洋参细胞的生理效应

报道了不同真菌诱导子对悬浮培养的西洋参（Ｐａｎａｘｑｕｉｎｑｕｅｆｏｌｉｕｍ）细胞生长、皂甙和多糖合成,以及细胞内和培养液中过氧化物酶活性的生理效应。悬浮培养的西洋参细胞经刺盘孢菌（Ｃｏｌｌｅｔｏｔｒｉｃｈｕｍｎｉｃｏｌｔｉａｎａｅ）丝体诱导子处理后,总皂甙产率可由对照的２９６ｍｇ／Ｌ增加到６７９ｍｇ／Ｌ（约占细胞干重的（１６．３％）,比对照提高约１．３倍,而且总皂甙的８５％排放在培养液中;经黑曲霉（Ａｓｐｅｒｇｉｌｌｕｓｎｉｇｒａｎ）诱导子处理后,细胞多糖含量可达到１１．７９％（细胞干重）,比对照增加１倍多。初步纯化的刺盘孢菌丝体诱导子和尖孢镰刀菌（Ｆｕｓｕｒｉｕｍｏｘｙｓｐｏｒｕｍ）滤液诱导子在诱导处理前期能明显促进西洋参细胞生长,同时细胞内及培养液中过氧化物酶活性显著增加;随时间延长,细胞生长和酶活性逐步受到抑制。     

The design and pharmacology of novel selective muscarinic agonists and antagonists

The muscarinic pharmacology of C1-methyl-substituted chiral compounds related to McN-A-343 and of (R)- and (S)-dimethindene has been studied. Among the McN-A-343 analogues, the (S)-enantiomers were more potent and had higher affinity than the (R)-isomers. The quaternary compound (S)-BN 228 was found to be the most potent M1-selective agonist known today (pEC50: M1/rabbit vas deferens = 7.83; M2/guinea-pig atria = 6.35; M3/guinea-pig ileum = 6.29). In both the atria and ileum the tertiary carbamate, (S)-4-F-MePyMcN, was a competitive antagonist (pA2 value = 7.39 and 6.82, respectively). In contrast, in rabbit vas deferens (S)-4-F-MePyMcN was a potent partial agonist (pEC50 = 7.22; apparent efficacy = 0.83). These results indicate that (S)-4-F-MePyMcN might be a useful tool to study M1 receptor-mediated effects involved in central cholinergic function. (S)-Dimethindene was a potent M2-selective antagonist (pA2 = 7.86/atria; pKi = 7.8/rat heart) with lower affinities for the M1 (pA2 = 6.36/rat duodenum; pKi = 7.1/NB-OK 1 cells), M3 (pA2 = 6.92/guinea-pig ileum; pKi = 6.7/rat pancreas) and M4 receptors (pKi = 7.0/rat striatum). It was more potent (up to 41-fold) than the (R)-isomer. In contrast, the stereoselectivity was inverse at ileal H1 receptors (pA2: (R)-isomer = 9.42; (S)-isomer = 7.48). Thus, (S)-dimethindene could be a valuable agent to test the hypothesis that M2 antagonists show beneficial effects in the treatment of cognitive disorders. It might also become the starting point for the development of diagnostic tools for quantifying M2 receptors in the CNS with PET imaging.     

柠檬酸发酵过程的动力学

发酵动力学是微生物培养过程研究中的一个重要部分,它让人们从理论和定量的角度了解和分析微生物的培养过程,是过程设计和控制的基础．柠檬酸发酵过程的动力学．Chemiel^[1]、Kristiansen^〔2〕、Khan^〔3〕、Rohr^〔4〕、Vaija^〔5〕等曾作过研究。本文在考察前人工作的基础上．结合实验研究．进行如下探索。     

Propylene oxide production from propylene by immobilized whole cells of Methylosinus sp. CRL 31 in a gas-solid bioreactor

Summary Methanotrophic bacteria have been shown to oxidize gaseous alkenes to the corresponding epoxides utilizing an NADH₂-dependent methane monooxygenase. A cell paste of methane-grown methylotrophs was coated on porous glass beads. The production of propylene oxide from propylene was performed in a gas-solid bioreactor to ensure continuous production and removal of product epoxide from the microenvironment of the biocatalyst. The amount of propylene oxide produced before cofactor regeneration was between 120–145 moles/20 mg cells in about 10 h depending on the microbial strains used. The conversion rate for propylene was 2.7%. Regeneration of cofactor NADH₂ was performed in the bioreactor with the vapor of a cosubstrate, methanol.