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81.
Complete larval development of Crangon hakodatei Rathbun isdescribed, based on material hatched in the laboratory fromovigerous females. The species has six zoeal stages and onepostlarval stage. The morphological characters of the larvaland postlarval stages are described with illustrative figuresand compared with those of two congeneric species. The zoealstages of C. hakodatei can be distinguished from those of otherCrangon species in the number of segments of the antennule peduncle,the number of setae on the antennal scale and basis of the maxillipeds,and the stages of appearance of pereiopods. The first zoealstage in the seven species of Crangon are compared and an annotatedkey for distinguishing them is also provided. 相似文献
82.
Genetic metabolic polymorphisms and the risk of cancer: a review of the literature 总被引:10,自引:0,他引:10
The purpose of this paper is to systematically analyse the design and results of epidemiological studies on the association between various types of cancer (lung, bladder, breast, colon, stomach) and four genetically-based metabolic polymorphisms, involved in the metabolism of several carcinogens (glutathione-S-transferase M1, debrisoquine hydroxylase, N acetyltransferase, aryl hydrocarbon hydroxylase). These inherited polymorphisms usually cause modifications in the quality or quantity of the relevant enzymes. Such enzymes are involved in the activation/inactivation of known carcinogens and seem to modify the extent to which carcinogens interact with DNA in target tissues. Two enzymes, debrisoquine hydroxylase and aryl hydrocarbon hydroxylase, activate procarcinogens to carcinogens (phase I enzymes). The other two, glutathione-S-transferase M1 and N-acetyltransferase, mainly detoxity carcinogenic substances (phase II enzymes). Because of their role as host factors (modulating the action of carcinogens), it has been hypothesized that subjects presenting a specific phenotype for such polymorphisms could be at a greater risk of developing various types of cancer. A number of epidemiological studies have investigated such associations, often with discordant results. We examine and discuss the design of the studies, and present a meta-analysis of the available data. 相似文献
83.
84.
Mei-Ling Siu-Caldera Jeffrey W. Clark Anabela Santos-Moore Sara Peleg Yan Yun Liu Milan R. Uskokovi Surendra Sharma G. Satyanarayana Reddy 《The Journal of steroid biochemistry and molecular biology》1996,59(5-6)
1α,25(OH)2-16-ene-D3, a synthetic analog of the steroid hormone, 1α,25(OH)2D3, has great potential to become a drug in the treatment of leukemia and other proliferative disorders, because of its minimal in vivo calcemic activity associated with a potent inhibitory effect on cell growth. However, at present, the mechanisms through which 1α,25(OH)2-16-ene-D3 expresses its biological activities are still not completely understood. Our previous in vitro study in a perfused rat kidney indicated for the first time that 1α,25(OH)2-16-ene-D3 and 1α,25(OH)2D3 are metabolized differently. 1α,25(OH)2-24-oxo-16-ene-D3, an intermediary metabolite of 1α,25(OH)2-16-ene-D3 formed through the C-24 oxidation pathway, accumulated significantly in the perfusate when compared to 1α,25(OH)2-24-oxo-D3, the corresponding intermediary metabolite of 1α,25(OH)2D3. In a subsequent in vivo study, we also reported that 1α,25(OH)2-24-oxo-16-ene-D3 exerted immunosuppressive activity equal to its parent, without causing significant hypercalcemia. In order to establish further the critical role of 1α,25(OH)2-24-oxo-16-ene-D3, in generating some of the key biological activities ascribed to its parent, we performed the present in vitro study using a human myeloid leukemic cell line (RWLeu-4) as a model. Comparative target tissue metabolism studies indicated that 1α,25(OH)2-16-ene-D3 and 1α,25(OH)2D3 are metabolized differently in RWLeu-4 cells, and the differences were similar to the ones we previously observed in the rat kidney. The significant finding was the accumulation of 1α,25(OH)2-24-oxo-16-ene-D3 in RWLeu-4 cells because of its resistance to further metabolism. Biological activity studies indicated that both 1α,25(OH)2-16-ene-D3 and its 24-oxo metabolite produced growth inhibition and promoted differentiation of RWLeu-4 cells to the same extent, and these activities were several fold higher than those exerted by 1α,25(OH)2D3. In addition, the genomic action of each vitamin D compound was assessed in a rat osteosarcoma cell line (ROS 17/2.8) by measuring its ability to transactivate a gene construct containing the vitamin D response element of the osteocalcin gene linked to the growth hormone reporter gene. In these studies, both 1α,25(OH)2-16-ene-D3 and its 24-oxo metabolite exerted similar but potent transactivation activity which was several fold greater than that exerted by 1α,25(OH)2D3 itself. In summary, our results indicate that the production and slow clearance of the bioactive intermediary metabolite, 1α,25(OH)2-24-oxo-16-ene-D3, in RWLeu-4 cells contributes significantly to the final expression of the enhanced biological activities ascribed to its parent analog, 1α,25(OH)2-16-ene-D3. 相似文献
85.
Summary
Chlorella vulgaris UTEX259 was cultivated using two different methods of gas supply. In one method the CO2 concentration in bubbled gas was held constant and in the other method it was increased gradually. Algal growth was almost linear after a short period of lag phase in both methods. With the constant CO2 concentration, the CO2 fixation rate in the linear growth phase decreased over 10%(v/v) CO2, while the rate increased up to 6% CO2. However, the rate was enhanced by using the latter incremental increase method, especially under a higher concentration of CO2. The maximum rate of CO2 fixation was 52 mg CO2/l·h at 20% CO2 during the gradual increase of CO2 concentration. 相似文献
86.
87.
萌发花生种子子叶肽链内切酶的纯化和性质 总被引:1,自引:0,他引:1
萌发花生种子子叶的肽链内切酶经硫酸铵沉淀,SephadexG-100凝胶层析,DEAE-纤维素23阴离子交换层析和DEAE-SephadexA50层析,得到纯化的酶,该酶有两条同工酶,分子量分别为58和55KD,Km为9.9μmol/L,是半胱氨型肽链内切酶(EC3.4.22),对未萌发花生种子的贮藏蛋白没有明显降解作用. 相似文献
88.
NAD激酶在光合作用等植物生理过程中起重要作用。NAD激酶的激活依赖于钙离子和钙调素(CalmOdulin,CaM).从植物中分离得到的一种新的CaM结合蛋白CaMBP-10(BP-10)明显抑制NAD激酶的激活活性,抑制作用可被CaM所克服.动力学研究表明,抑制效应是BP-10与CaM之间特异性相互作用的结果。实验证实BP-10对NAD激酶活性起着重要调节作用. 相似文献
89.
海南坡鹿对生境的选择 总被引:5,自引:0,他引:5
1987~1994年,在海南省大田自然保护区及其外围地带对坡鹿的生境选择性进行了调查,发现坡鹿对自然生境有较强的选择性。对不同的生境的选择频率为:落叶季雨林生境47.93%;灌木草地生境39.14%;有刺灌丛生境10.72%;人工林生境2.21%。还对各种生境进行了评价;并提出了保护生境的对策 相似文献
90.
Yuh-Shyong Yang A.David Marshall Peter Mcphie Wei-Xi Athena Guo Xiaofu Xie Xiang Chen William B. Jakoby 《Protein expression and purification》1996,8(4):423-429
A phenol sulfotransferase from rat liver (EC 2.8.2.9), expressed inEscherichia colifrom a single cDNA, was purified as two separable but catalytically active proteins. The proteins appeared to be identical to each other and to the natural liver sulfotransferase by comparison of their amino acid constitution, amino-terminal end group, and interaction with a polyclonal antibody raised against the liver enzyme. Each of the recombinant forms, α and β, catalyzed the sulfuryl group transfer from 4-nitrophenylsulfate to an acceptor phenol, a reaction in which 3′-phospho-adenosine 5′-phosphate (PAP) is a necessary intermediate. Only form β, however, catalyzes the physiological transfer of a sulfuryl group from 3′-phosphoadenosine 5′-phosphosulfate (PAPS) to the free phenol. Evidence is presented that sulfotransferase α, but not β, has 1 mol of PAP tightly bound per enzyme dimer. The ability to utilize PAPS as a sulfate donor could be altered: form α could be treated and purified as form β to acquire the ability to use PAPS, whereas form β was treated by extended incubation with PAP, lost its ability to use PAPS, and was purified as form α. 相似文献