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61.
The effects of primary electron-donor and electron-acceptor substrates on the kinetics of TCA biodegradation in sulfate-reducing and methanogenic biofilm reactors are presented. Of the common anaerobic electron-donor substrates that were tested, only formate stimulated the TCA biodegradation rate in both reactors. In the sulfate-reducing reactor, glucose also stimulated the reaction rate. The effects of formate and sulfate on TCA biodegradation kinetics were analyzed using a model for primary substrate effects on reductive dehalogenation. Although some differences between the model and the data are evident, the observed responses of the TCA degradation rate to formate and sulfate were consistent with the model. Formate stimulated the TCA degradation rate in both reactors over the entire range of TCA concentrations that were studied (from 50 g TCA/L to 100 mg TCA/L). The largest effects occurred at high TCA concentrations, where the dehalogenation kinetics were zero order. Sulfate inhibited the first-order TCA degradation rate in the sulfate-reducing reactor, but not in the methanogenic reactor. Molybdate, which is a selective inhibitor of sulfate reduction, stimulated the TCA removal rate in the sulfate-reducing reactor, but had no effect in the methanogenic reactor. 相似文献
62.
对1587名献血员进行了抗-HCV检测,总阳性率5.60%,在不同职业中农民较高,占6.72%,30岁以上为12.76%。我站自改进采浆工艺,严格使用一次性消毒器具后,未发现HCV交叉感染。职业献血者抗-HCV阳性率高达35.48%,易造成输血后HCV感染。对HCV感染OD值阳性30人又进行4-6个月的观察复测,其中16人OD值下降,6人上升,认为OD值的变化与自限性HCV感染有关。 相似文献
63.
The application of molecular markers to the study and conservation of fish populations, with special reference to Salmo 总被引:4,自引:0,他引:4
A. Ferguson J. B. Taggart † P. A. Prodöhl ‡ O. McMeel C. Thompson § C. Stone P. McGinnity R. A. Hynes 《Journal of fish biology》1995,47(SA):103-126
The main molecular techniques which can be used to generate genetic markers, and the applications of these markers to studies of fish populations are outlined. Published and ongoing studies, in the authors' laboratories, on brown trout and Atlantic salmon are used to compare the resolution and applicability of allozyme, mitochondrial DNA and minisatellite (variable number of tandem repeats) markers for studies on population structuring, genetic variation within populations, and the impact of the accidental and deliberate introduction of non-native salmonids on the genetic make-up of natural populations. 相似文献
64.
Martin Burd 《Evolution; international journal of organic evolution》1995,49(1):100-109
The modular morphology of plants has important consequences for reproductive strategies. Ovules are packaged in discrete structures (flowers) that usually vary stochastically in pollen capture and ovule fertilization, because of the vagaries of pollen transfer by external agents. Different ovule packaging schemes may use limited reproductive resources more or less effectively, so that some number of ovules per flower may be optimal, given the prevailing probabilities of ovule fertilization. I derive a phenotypic model for ovule number per flower that maximizes the expected total ovule fertilizations on a plant when pollination and fertilization vary randomly among individual flowers. This model predicts that, except for small or inexpensive flowers, ovules should be “oversupplied” relative to the mean receipt of pollen tubes, so that pollen limitation of seed set should be common. Published data are congruent with this prediction. Additional hypotheses on the relation of ovule packaging to floral cost, plant size, and variance in pollen receipt are suggested by the model, but few data exist to evaluate these hypotheses. 相似文献
65.
宋光江 李桂信 李启清 孙安堂 宋兴军 杜克明 刘京升SONG Guang-Jiang LI Gui-Xin LI Qi-Qing SUN An-Tang SONG Xing-Jun DU Ke-Ming LIU Jiang-Sheng 《遗传》1995,17(4):1-3
CT所见肝脏肿大占据左右上腹,纠正了既往把肝左叶当做脾大的结论;B超发现前所没有报道的二尖瓣赘生物将给患者终生致残;标准品DS行双向电泳,首次发现其分离为DS1与GS2两个斑点;杂合子、患者尿GAG均出现DS1斑点,而正常人则不出现。实验显示,DS1的出现在杂合子检出和患者确诊上有重要意义。 相似文献
66.
Christian Biémont Cristina Vieira Christine Hoogland Géraldine Cizeron Catherine Lœvenbruck Claude Arnault Jean-Pierre Carante 《Genetica》1997,100(1-3):161-166
To investigate the main forces controlling the containment of transposable elements (TE) in natural populations, we analyzed
the copia, mdg1, and 412 elements in various populations of Drosophila melanogaster and D. simulans. A lower proportion of
insertion sites on the X chromosome in comparison with the autosomes suggests that selection against the detrimental effects
of TE insertions is the major force containing TE copies in populations of Drosophila. This selection effect hypothesis is
strengthened by the absence of the negative correlation between recombination rate and TE copy number along the chromosomes,
which was expected under the alternative ectopic exchange model (selection against the deleterious rearrangements promoted
by recombination between TE insertions). A cline in 412 copy number in relation to latitude was observed among the natural
populations of D. simulans, with very high numbers existing in some local populations (around 60 copies in a sample from Canberra,
Australia). An apparent absence of selection effects in this Canberra sample and a value of transposition rate equal to 1–2
× 10-3 whatever the population and its copy number agree with the idea of recent but temporarily drastic TE movements in local populations.
The high values of transposition rate in D. simulans clearly disfavor the hypothesis that the low amount of transposable elements
in this species could result from a low transposition rate.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
67.
68.
蓟属两种植物的染色体研究 总被引:2,自引:0,他引:2
本文对蓟属(Cirsium)的两个形态相似的近缘种大刺儿菜和小刺儿菜进行了染色体研究,其中后者为首次报道。观察结果表明:两个种的染色体数目均为2n=2x=34:它们的核型是:大刺儿菜.2n=2x=34=20m+12sm+2st:小刺儿菜.2n=2x=34=22m+10km(2SAT)+2st。通过核型比较,认为它们是两个独立的种.而且后者比前者进化。 相似文献
69.
70.