灭幼脲对亚洲玉米螟胚胎气管系统形成的影响

初产下的亚洲玉米螟Ostrinia furnacalis(Guenée)卵,经灭幼脲处理,观察发现:具有抑制几丁质合成性能的灭幼脲对该种害虫的胚胎发育阶段不导致中断,而对气管系统的发生和形成产生严重阻碍.卵内幼虫近孵化时不能开始气管呼吸,生命活动停滞,死于卵壳内.这观察结果可阐明灭幼脲的杀卵机制,并指出更好地应用灭幼脲的途径.     

佛波醇酯诱导HL-60细胞巨噬细胞样分化时蛋白激酶C活力及分布的改变

本文对佛波醇酶诱导人早幼粒白血病细胞系HL-60细胞分化为巨噬细胞样细胞对蛋白激酶c活力及其在亚细胞分布的变化进行了研究。蛋白激酶c活力在TPA处理1小时即明显降低,此低水平的酶活力持续整个实验时期。酶的亚细胞分布研究提示TPA处理细胞胞质组分酶活力剧烈降低,而颗粒组分存在一高盐浓度洗脱的酶活力峰。蛋白激酶c抑制剂三氟过(口了)嗪单独处理HL-60细胞导致胞质和颗粒组分酶活力升高,但并不诱导细胞分化;若与TPA合并处理细胞,酶活力又降低,此时细胞又分化为巨噬细胞样细胞。对上述结果的可能机理进行了讨论。     

Current densities induced in swine and rat models by power-frequency electric fields

Measurements have been made of vector current densities induced by vertical, uniform, 60-Hz electric fields in the torsos of homogeneous models of swine and rats. The observed data were a strong function of the five grounding configurations invested: all four feet grounded, only front feet grounded, only rear feet grounded, left front and right rear feet grounded, and right front and left rear feet grounded. In the first configuration and with an exposure field strength of 10 kV/m, average total current densities induced in the torsos of pigs and rats were 34 nA/cm2 and 20 nA/cm2, respectively. The corresponding value for human exposure is about 250 nA/cm2, 7.3 and 12.5 times larger than for swine and rats, respectively. Current densities measured at 60 Hz can be linearly extrapolated to frequencies in a range extending from at least 1 Hz to 1 MHz. Human and animal current-density data can provide an improved rationale for extrapolating biological data across species. In addition, these data can be used to validate the predictions of numerical models.     

Inhibition by 1 alpha,25-dihydroxyvitamin D3 of dimethyl sulfoxide-induced differentiation of Friend erythroleukemia cells

Regulation of erythroid differentiation by vitamin D3 derivatives was examined in Friend erythroleukemia cells. After Friend cells were cultured for 5 days with 1.5% dimethyl sulfoxide (DMSO), as much as 70% of the cells became benzidine-positive and the hemoglobin content increased in parallel with the increase of benzidine-positive cells. The DMSO-induced erythroid differentiation was markedly inhibited by concurrent addition of the active form of vitamin D3, 1 alpha,25-dihydroxyvitamin D3 [1 alpha,25(OH)2D3]. Of the vitamin D3 derivatives tested, 1 alpha,25(OH)2D3 was the most potent in inhibiting DMSO-induced erythroid differentiation. 1 alpha,25(OH)2D3 alone was totally ineffective in both cell growth and erythroid differentiation. These results together with our previous reports indicate that 1 alpha,25(OH)2D3 is somehow involved not only in myeloid differentiation, but also in erythroid differentiation.     

3H]Ouabain binding and 86 rubidium uptake during the dimethyl sulfoxide-induced differentiation of human promyelocytic leukemia HL-60 cells

When HL-60 cells were induced to differentiate into granulocyte-like cells by culture in the presence of 1.3% dimethyl sulfoxide, an increase in the rate of ouabain-sensitive 86Rb transport was observed during the first 6 h followed by a constant decrease which became stable on day 4 at about 40% of control level. By contrast, the number of ouabain binding sites remained constant during the first 24 h then decreased with the same kinetics as that of the 86Rb transport rate. These results suggest that alterations in ionic fluxes, through activation of the sodium pump, are part of the early events resulting in HL-60 cell differentiation.     

Preparations ofN,N′-ethylene-bridged dipeptides(eXX) constructed from (S)-methionine, -tryptophan, -tyrosine and-N(ɛ)-benzyloxycarbonyllysine through acid-catalyzed cyclization

Summary N, N60j7372772285/xxlarge8242.gif" alt="prime" align="BASELINE" BORDER="0">-Ethylene-bridged bis-(S)-methionine[(2S, 7S)-2, 7-bis(2-methyl-thioethyl)-3,6-diazaoctanedioic acid] derived from (S)-methionine and 1,2-dibromoethane was cyclized and esterified simultaneously in boiling ethanol in the presence of an appropriate amount of strong acid such asp-toluenesulfonic acid, affording a cyclic compound,N, N60j7372772285/xxlarge8242.gif" alt="prime" align="BASELINE" BORDER="0">-ethylene-bridged (S)-methionyl-(S)-methionine ethyl ester {ethyl(2S, 360j7372772285/xxlarge8242.gif" alt="prime" align="BASELINE" BORDER="0">S)-4-(methylthio)-2-[260j7372772285/xxlarge8242.gif" alt="prime" align="BASELINE" BORDER="0">-oxo-360j7372772285/xxlarge8242.gif" alt="prime" align="BASELINE" BORDER="0">-(2-methylthioethyl)-160j7372772285/xxlarge8242.gif" alt="prime" align="BASELINE" BORDER="0">-piperazinyl] butanoate}, exclusively in 80–90% yields. It was also found that, by applying this method, 70–80% yields of the otherN, N60j7372772285/xxlarge8242.gif" alt="prime" align="BASELINE" BORDER="0">-ethylenebridged dipeptides containing (S)-tryptophan, -tyrosine and -N(60j7372772285/xxlarge603.gif" alt="epsiv" align="BASELINE" BORDER="0">)-benzyloxycarbonyllysine were obtained.     

^60Co—γ辐射对尼氏钝绥螨抗多虫畏性状的诱导及其它生物学效应

本文首次报道了＾６０Ｃｏ－γ射线辐笛射诱导抗药性产生的方法,以２０００拉德的剂量辐射３次,约１年时间培育出尼氏钝绥螨Ａｍｂｌｙｓｅｉｕｓ ｎｉｃｈｏｌｓｉ Ｅｈａｒａ ｅｔ Ｌｅｅ对拟除虫菊酯农药多虫畏具抗性的两个品系：单抗１（ＦＲ１）与双抗（ＰＦＲ）品系。多虫畏对其致死中浓度ＬＣ５０由敏感品系的８．２２×１０＾－５ｐｐｍ分别提高到１．３３４７×１０＾－３和１．４３０７×１０＾－３,抗性水平提高２     

Expression of one of the members of the Arabidopsis chaperonin 60β gene family is developmentally regulated and wound-repressible

To study the pattern of gene regulation of the plastid chaperonin 606036054656120/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0"> gene family a chimaeric gene was constructed fusing the 56036054656120/xxlarge8242.gif" alt="prime" align="BASELINE" BORDER="0">-flanking region of the chaperonin 606036054656120/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0"> B3 gene to the 6036054656120/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">-glucuronidase reporter gene. Histochemical and fluorometric analysis of the GUS activity present in transgenic plants harbouring this gene construct showed that the B3 promoter is expressed in leaves, stem, petioles and several flower tissues. The pattern of cell type-specific expression in stems and flowers was found to be developmentally regulated. Expression of the B3 promoter was found not to be heat-inducible, but highly repressed by wounding. The rapid decay in GUS activity upon wounding indicates that, at least under some physiological conditions, the gene product of this reporter gene is not as stable as has been previously thought.     

Differential effects of Ca2+ and Mg2+ on endonuclease activation in isolated promyelocytic HL-60 cell nuclei

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60 Hz magnetic field exposure induces DNA crosslinks in rat brain cells

In previous research, we found an increase in DNA strand breaks in brain cells of rats acutely exposed to a 60 Hz magnetic field (for 2 h at an intensity of 0.5 mT). DNA strand breaks were measured with a microgel electrophoresis assay using the length of DNA migration as an index. In the present experiment, we found that most of the magnetic field-induced increase in DNA migration was observed only after proteinase-K treatment, suggesting that the field caused DNA-protein crosslinks. In addition, when brain cells from control rats were exposed to X-rays, an increase in DNA migration was observed, the extent of which was independent of proteinase-K treatment. However, the X-ray-induced increase in DNA migration was retarded in cells from animals exposed to magnetic fields even after proteinase-K treatment, suggesting that DNA-DNA crosslinks were also induced by the magnetic field. The effects of magnetic fields were also compared with those of a known DNA crosslink-inducing agent mitomycin C. The pattern of effects is similar between the two agents. These data suggest that both DNA-protein and DNA-DNA crosslinks are formed in brain cells of rats after acute exposure to a 60 Hz magnetic field.