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121.
Degradation of Dehydrodivanillin by Anaerobic Bacteria from Cow Rumen Fluid 总被引:7,自引:7,他引:0
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Dehydrodivanillin (DDV; 0.15 g/liter) was biodegradable at 37°C under strictly anaerobic conditions by microflora from cow rumen fluid to the extent of 25% within 2 days in a yeast extract medium. The anaerobes were acclimated on DDV for 2 weeks, leading to DDV-degrading microflora with rates of degradation eight times higher than those initially. Dehydrodivanillic acid and vanillic acid were detected in an ethylacetate extract of a DDV-enriched culture broth by thin-layer, gas, and high-performance liquid chromatographies and by mass spectrometry. 相似文献
122.
The natural products of both eremofortin C (EC) and PR toxin are secondary metabolites of Penicillium roqueforti. Because the chemical structures of EC and PR toxin are closely related to each other and differ only by a hydroxyl functional group in EC and an aldehyde functional group in PR toxin at the C-12 position, the chemical transformation of EC into PR toxin was investigated. Oxidation with a chromic anhydride-pyridine complex was found to be the most satisfactory method. 相似文献
123.
Using recombinant DNA techniques, the covalent structure was determined for three flagellar filament proteins produced by Salmonella serotypes with phase-1 antigens a, c and d. Comparison of the results obtained, together with previous results for antigen i, indicated an overall structure in which conservation of amino acid sequence was absolute at both ends of the molecule and proceeded inwards with progressively greater variation. Very few differences in nucleotide sequence were detected in regions of amino acid conservation, which suggested that these areas of the gene may be involved in regulatory functions. 相似文献
124.
T6 DNA topoisomerase has been purified from bacteriophage T6 infected Escherichia coli. Unlike the T4 DNA topoisomerase which has three subunits, it consists of two subunits of molecular weights 75,000 and 51,000. They are the products of T6 genes 39 and 52, respectively. The purified T6 enzyme can stimulate in vitro T6 DNA replication. It has an ATP-dependent DNA relaxation activity similar to the T4 enzyme. Either ATP or dATP can be used in both reactions. Using a "Western blotting" and radioimmuno-detection methods, we show that T6 39 subunit contains protein sequences specified by both the T4 39 and 60 genes. The 52-proteins of both phages appear to be identical. The T4 and T6 topoisomerase genes represent a naturally occurring example of gene separation or fusion. 相似文献
125.
Abstract The time course of loading and transport of assimilate in sunflower leaves was examined by pulse labelling with 14CO2, followed by freeze drying or freeze substitution, and dry autoradiography at both low and high resolution. The five classes of veins, V1-V5 (V5 being smallest), show a division of function: V5 and V4 are engaged in loading and short distance transport; V3 to V1, in long distance translocation. The first high concentration of 14C is found in two or three phloem parenchyma cells (intermediary cells) of V5 and V4 veins. The sieve elements of V5 and V4 veins do not show comparable concentrations of 14C at any time. Recently assimilated 14C is transported by the intermediary cells for distances of about 0.5 mm to the V3 veins. In V3 to V1 veins translocation is in the sieve tubes. Transport in V5 and V4 veins is in two directions, that in V3 to V1, in one direction towards the petiole. The high concentration of 14C formed in the intermediary cells does not increase further as the assimilate moves to the sieve tubes of the V3 veins, and so is probably the origin of the gradient that drives translocation. 相似文献
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本文记述樟蚕姬蜂属Habronyx Foerster指名亚属Habronyx(s.str.)中的一新种。标本采自北京潭柘寺。模式标本保存在中国科学院动物研究所。本文特征图由陆伯林同志绘制。 拟榨蚕软姬蜂 Habronyx subinsidiator新种 雌蜂:前翅长12毫米。头、胸黑色。触角柄节、梗节前面、脸、唇基、上颚除端齿外、眼眶外侧下端、触角鞭节、前足、中足、后足除基节及胫节端部外、翅基片、腹部除第二节背部纵斑外均黄至红黄色。翅脉褐色,翅痣浅褐,翅浅褐透明。体被致密短毛。头宽与胸宽 相似文献
129.
由开花前1—4天的向日葵子房中取出胚珠,在液体培养基上进行漂浮培养,诱导了未受精的卵细胞发育为单倍体的胚状体.亦诱导了珠被绒毡层产生胚状体。对两种胚状体的发生和发育过程及其形态发生特点作了显微观察与描述。 相似文献
130.
在缺钾培养条件下,高粱苗地上部单位鲜重含钾量由于地上部鲜重的增加而下降。从高梁苗钾缺乏症出现的时间、频率和程度来看,Pro培养似乎有利于缓和或减轻缺钾对植物造成的伤害。在同样含钾量情况下,以Ca(NO_3)_2为氮源的苗受到缺钾伤害要重于以Pro为氮源的苗受到的伤害,其钾缺乏症植株的百分数增加值与含钾量降低值之比为0.26,以Pro为氮源的缺钾营养液培养的苗为0.09,即下降同样量的钾前者苗的钾缺乏症的增加要大大地超过后者。Pro并不减轻在缺钾情况下叶绿素含量的下降。 相似文献