Clerodane diterpenoids from the roots of Portulaca pilosa

Three trans-clerodane diterpenoids, pilosanol A, B and C, the last compound being a glucoside, have been isolated from the roots of Portulaca pilosa. They show a marked contrast in skeletal type with the constituents of aerial part. Evolutionary changes in the biosynthetic abilities of Portulaca species is discussed.     

Transfer of Hessian fly resistance from rye to wheat via radiation-induced terminal and intercalary chromosomal translocations

Summary A new Hessian fly (Mayetiola destructor) resistance gene derived from Balbo rye and its transfer to hexaploid wheat via radiation-induced terminal and intercalary chromosomal translocations are described. Crosses between resistant Balbo rye and susceptible Suwon 92 wheat and between the F₁ amphidiploids and susceptible TAM 106 and Amigo wheats produced resistant BC₂F₃ lines that were identified by C-banding analysis as being 6RL telocentric addition lines. Comparative chromosomal analyses and resistance tests revealed that the resistance gene is located on the 6RL telocentric chromosome. X-irradiated pollen of 6RL addition plants was used to fertilize plants of susceptible wheats TAM 106, TAM 101, and Vona. After several generations of selection for resistance, new sublines were obtained that were homogeneous for resistance. Thirteen of these lines were analyzed by C-banding, and three different wheat-6RL chromosomal translocations (T) were identified. Wheat chromosomes involved in the translocations were 6B, 4B, and 4A. Almost the complete 6RL arm is present in T6BS · 6BL-6RL. Only the distal half of 6RL is present in T4BS · 4BL-6RL, which locates the resistance gene in the distal half of 6RL. Only a very small segment (ca 1.0 m) of the distal region of 6RL is present in an intercalary translocation (Ti) Ti4AS · 4AL-6RL-4AL. The 6RL segment is inserted in the intercalary region between the centromere of chromosome 4A and the large proximal C-band of 4AL. The break-points of the translocations are outside the region of the centromere, indicating that they were induced by the X-ray treatment. All three translocations are cytologically stable and can be used directly in wheat breeding programs.Cooperative investigations of the Kansas Agricultural Experiment Station, Departments of Entomology and Plant Pathology, the Wheat Genetics Resource Center, Kansas State University, and the US Department of Agriculture, Agricultural Research Service. Contribution No. 91-117-JDeceased     

Protein kinase C activating phorbolesters enhance the cyclic AMP response to parathyroid hormone,forskolin and choleratoxin in mouse calvarial bones and rat osteosarcoma cells

The protein kinase C-(PKC) activating phorbol esters 12-O-tetradecanoylphorbol-13-acetate (TPA; 100 nmol/l) and phorbol 12, 13-dibutyrate (PDBU; 100 nmol/l) enhanced basal cyclin AMP accumulation in cultured neonatal mouse calvaria. The cyclic AMP response to parathyroid hormone (PTH; 10 nmol/l) and the adenylate cyclase activators forskolin (1–3 mol/l) and choleratoxin (0.1 mg/ml) was potentiated in a more than additive manner by TPA and PDBU. In contrast, phorbol 13-monoacetate (phorb-13; 100 nmol/l), a related compound but inactive on PKC, had no effect on basal or stimulated cyclic AMP accumulation. In the presence of indomethacin (1mol/l), TPA and PDBU had no effect on cyclic AMP accumulation in calvarial bones per se, but were still able to cause a significant enhancement of the response to PTH, forskolin and choleratoxin. PTH-, forskolin- and choleratoxin-stimulated cyclic AMP accumulation in rat osteosarcoma cells UMR 106-01 was synergistically potentiated by TPA and PDBU, but not by phorb.-13. These data indicate that PKC enhances cyclic AMP formation and that the level of interaction may be at, or distal to, adenylate cyclase.     

Measurement of two-bond JCOHα coupling constants in proteins uniformly enriched with13C

Summary A simple E.COSY type technique is described for measurement of two-bond J_COH coupling constants in proteins that are uniformly enriched with¹³C. The method has been used to measure²J_COH for 132 residues in the proteins calmodulin and staphylococcal nuclease having non-overlapping H–C correlations. Measured²J_COH coupling constants fall in the 0 to –9.5 Hz range. A separate experiment, measuring the accuracy of these values, indicates a root-mean-square error of 1 Hz. Comparison of the J couplings with the dihedral back bone angles from crystallographic studies confirms a weak but statistically significant correlation between the dihedral angle and the magnitude of²J_COH, but also indicates that parameters other than have a significant effect on the value of the coupling.     

Lithium treatment of affective disorders: effects of lithium on the inositol phospholipid and cyclic AMP signalling pathways

The effects of lithium (Li⁺) on the adenylyl cyclase and inositol phospholipid receptor signalling pathways were compared directly in noradrenergic and carbachol stimulated rat brain cortical tissue slices. Li⁺ was a comparatively weak inhibitor of noradrenaline-stimulated cyclic AMP accumulation with an IC₅₀ of approx. 20 mM. By contrast, half-maximal effects of Li⁺ on inositol monophosphate (InsP) accumulation in [³H]inositol labelled tissue slices occurred at about 1 mM. A similar IC₅₀ for Li⁺ of about 1 mM was also obtained for noradrenaline-stimulated accumulation of CMP-phosphatidate (CMPPA), a sensitive indicator of intracellular inositol depletion, in tissue slices that had been prelabelled with [³H]cytidine. The effect of myo-inositol (inositol) depletion on the prolonged activity of phosphoinositidase C (PIC) was examined in carbachol-stimulated corticol slices using a novel mass assay fro InsP. Exposure to a maximal dose of carbachol for 30 min in the presence of 5 mM Li⁺ caused a 10-fold increase in the level of radioactivity associated with the InsP fraction, but only a 2-fold increase in InsP mass. During prolonged incubations in the presence of both carbachol and Li⁺ the accumulation of InsP mass was enhanced if 30 mM inositol was included in the medium. The results are comptable with the inositol depletion hypothesis of Li⁺ action but do not support the concept that adenylyl cyclase or guanine nucleotide dependent proteins represent therapeutically relevant targets of this drug.     

湖泊和地下水中异养细菌群落结构和生理特征的比较研究

对武汉东湖三个定点观测站和潜江市一深水机井中异养细菌群落的种群组成、对不同基质的反应、菌株和群落的生理特征和活力水平等方面比较研究结果表明:环境差异较小的东湖Ⅰ、Ⅱ、Ⅲ站异养细菌群落间的差异亦较小,具有类似的结构特征和生理活力水平,对特定基质表现了相似的作用模式;地下水中的异养细菌群落在上述几方面均显示了明显的差别。此外,在异养细菌群落结构和功能研究方法上亦是有益的探讨。     

Cu~(2+),Cu~(2+)/Vit C对亚油酸过氧化起动机理的ESR研究

本文直接用亚油酸为材料,利用ESR自旋捕集技术和紫外分光技术,分别检测了脂质过氧化反应过程中产生的中间自由基产物L·和共轭二烯结构,对Cu~(2+),Cu~(2+)/Vit C起动脂质过氧化反应的机理进行了研究。结果表明:Vit C自由基,Cu~(2+),Cu~+都不能起动纯的亚油酸的过氧化;Cu~(2+),Cu~+可以使含有部分过氧化成份的亚油酸继续氧化。     

中华眼镜蛇蛇毒因子(CVF)对补体系统的作用及与人补作C_3和其他蛇毒抗原性关系

中华眼镜蛇蛇毒经DEAE-Sepharose CL-6B。HPLC等多次柱层析分离出有抗补体及溶血活性的眼镜蛇蛇毒因子(Cobra venom factor,CVF),纯化后的CVF在聚丙烯酰胺凝胶电泳图谱上呈单一区带,分子量为225000—230000,等电点为6.20。用二硫苏糖醇还原经SDS-聚丙烯酰胺凝胶电泳得三类亚基,其分子量总和为237,000。 体外抗补体及溶血试验表明,CVF的作用是通过补体旁路途经使总补体活力下降。双向免疫电泳鉴定,发现CVF与人血清作用后,其中补体成分C_3分子的抗原性发生改变,则表明CVF的作用是通过激活补体成分C_3而发挥的。给豚鼠腹腔注射CVF(0.15ug/g体重)后,其血清总补体水平下降到正常值的3％以下,7天后回升,13天后恢复到正常水平。 单相免疫电泳表明,CVF与人补体C_3抗血清间无任何交叉免疫反应,但人血清与CVF抗血清间有微弱的免疫沉淀反应。另外,CVF的氨基酸组成与人补体C_3也较为相似。鉴定还表明眼镜蛇科中四种蛇毒与CVF抗血清有强烈的免疫沉淀反应,蝰蛇毒及海蛇毒也有免疫沉淀反应,但只有眼镜蛇毒具有抗补体活性。