螺旋霉素的生物合成——Ⅰ.用静息细胞系统研究影响因素

本文利用静息细胞系统研究了各种因素对螺旋霉索(SPM)合成的影响。结果发现,当种子菌龄为46h,培养基的pH为6.2,静息培养时间为18h时,对SPM合成最有利;乙酸盐、甲硫氨酸有明显的促进作用,当乙酸加入量为1%时可提高SPM效价一倍;加入0.01%的甲硫氨酸,SPM产量增加50%,SPM的合成对NH_4~+比较敏感,当系统中NH_4Cl的含量达0.4%时,SPM的合成减少42%,如同时加入0.1%KH_2PO_4,可降低NH_4~+浓度1/3,从而解除NH_4~+的阻遏作用。此外,还发现0.1%KH_2PO_4不仅能解除外源SPM对SPM合成的抑制作用,并且能提高菌的生物合成活力近一倍。在静息细胞系统中加入氯霉素,发现SPM的合成是从培养30h后开始的。     

硒化蓖麻酸对肿瘤细胞DNA合成的影响

大量的研究报道表明,克山病、大骨节病与缺硒有关,多种肿瘤的发生率也与周围环境硒含量呈负相关,说明微量元素硒具有多种生物学功能.补硒能预防并抑制肿瘤发生和发展;自60年代起,就有关于不饱和脂肪酸抗肿瘤的报道.笔者将硒与一种不饱和脂肪酸——蓖麻酸共价结合,使之形成硒化蓖麻酸,并对其体内外抗肿瘤活性进行了研究,结果表明:硒化蓖麻酸具有较强的抗肿瘤活性.其作用机理及对肿瘤     

Replication pattern of double minutes derived from an insect cell line

Summary The DNA replication pattern of double minutes derived from an established cell line ofAedes albopictus is described. Although the vast majority of double minutes replicate semiconservatively once during the S phase, some double minutes appear to exhibit different pattern(s). Two theories are suggested as possible explanations of our findings.This work was supported by a grant from the Whitehall Foundation, Inc. awarded to A.B.M.     

突变质体在细胞内传递的纯合速度及其依承关系

研究了纯合率Ｐ＾０ｎ＋Ｐ＾ｍｎ与细胞分裂次数ｎ，起始细胞含突变质体的个数１，细胞内含质体数目ｍ之间的相互依承关系，并通过机穷举计算验证与数学逻辑推理相结合的方法揭示了有关内在规律。     

实际面间距的简捷计算方法

通过分析结晶学晶胞和固体物理原胞之间的异同点和相互联系，导出了一种计算面间距的简捷方法，该方法有效地综合了二者的优点，即可免去插入平面的麻烦，双可方便直接地求出实际面间距。     

U形渠道直壁式量水槽过渡段曲面的设计

针对U形渠道过渡段制作精度难以控制，进而影响量水槽的量水精度这一问题，推导了U形渠道直壁式量水槽过渡段曲面的设计方法，为过渡段曲面的准确计算提供了依据。算例结果表明，该方法在量水槽的设计、制模和制作中能保证精度，可供有关技术人员参考。     

JAVA如何读取EXCEL文件

简要介绍了开放源码项目Java Excel API，结合示例，详细叙述了有关Excel文件的读取方法，最后给出了一个例程及其运行结果。     

Plasma enteroglucagon,peptide YY and gastrin in rats deprived of luminal nutrition,and after urogastrone-EGF administration. A proliferative role for PYY in the intestinal epithelium?

Intestinal tissue mass was significantly reduced throughout the gastrointestinal tract (p<0.001) of=" intravenously=" fed=" (tpn)=" rats.=" urogastrone-epidermal=" growth=" factor,=" (uro-egf),=" reversed=" these=" changes.=" although=" plasma=" enteroglucagon=" and=" gastrin=" levels=" showed=" a=" small=" increase=" with=" uro-egf,=" this=" was=" far=" less=" than=" the=" gut=" tissue=" weight=" change,=" suggesting=" that=" it=" was=" unlikely=" that=" they=" were=" involved=" in=" modulating=" the=" proliferative=" response=" of=" the=" intestine=" to=" uro-egf.=" peptide=" tyrosine=" tyrosine=" (pyy)=" levels=" were=" however=" significantly=" increased=" by=" uro-egf,=" indicating=" that=" pyy=" may=" possibly=" have=" a=" role=" in=" the=" modulation=" of=" intestinal=" cell=">We thank the Cancer Research Campaign for their financial assistance and acknowledge the technical assistance of Mr W. Lenton.     

The use of 5-fluorocytosine and ketoconazole in the culture of the erythrocytic stages ofPlasmodium falciparum and some tumor cell lines

Summary In vitro culture systems are often contaminated by bacteria and fungi. It is therefore often necessary to supplement culture media with agents such as penicillin/streptomycin, gentamycin or amphotericin B. The latter cannot be used in the in vitro culture of erythrocytic stages ofP. falciparum, and thus anti-fungal agents have not been regularly used in this system. We describe the prophylactic use of 5-fluorocytosine (5-FC) and ketoconazole (KTZ) in tissue cultures at concentrations up to 300 and 10 g/ml respectively which have no effect on the growth ofP. falciparum (FCR-3 strain). A melanoma cell line (C32) and a line of uterine carcinoma (C41) were also unaffected by similar concentrations of 5-FC and KTZ. When dissolved in complete culture medium (RPMI 1640) with 10% human plasma, the minimum inhibitory concentration of 5-FC for a susceptible strain ofCandida remained below 2 g/ml. These experiments suggest that 5-FC (at 50 g/ml) alone or in combination with KTZ (at 1 g/ml) is a useful addition to the armamentarium of antimicrobials available to the tissue culture biologist for a variety of cell culture systems.