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11.
本文报导了用He—Ne激光辐照真菌米曲酶的酯酶同工酶和淀粉同工酶的分析研究结果,实验表明激光对米曲霉同工酶有一定的影响。 相似文献
12.
本研究于2021年3~9月,采用目标观察和全事件记录法,对广西防城港市钦州湾八路水湿地黑翅长脚鹬(Himantopus himantopus)的繁殖习性进行全过程观察记录。黑翅长脚鹬的栖息生境主要在盐田、虾塘和鱼塘,而巢主要分布在盐田生境。共发现39巢,雌雄共同营巢,按照主要巢材将其巢分为干草巢、碎石巢、泥皮巢和牛毛毡草巢4种;巢材包括禾本科(Gramineae)和莎草科(Cyperaceae)植物以及碎石、贝壳等;巢外径为(23.3±10.7)cm,巢内径为(11.2±1.9)cm,巢深为(1.6±0.5)cm,巢高为(6.5±4.3)cm(n=39);筑巢需(3±2)d(n=6)。窝卵数2~4枚,1~2 d产1枚卵,7 d内产完满窝卵(n=6)。雌雄均参与孵卵,雄性孵卵时间比雌性长,但二者差异不显著(P> 0.05),雄性(8 550±245.9)min,雌性(7 530±263.3)min,孵卵期为(25±2)d(n=6)。育雏期(26±3)d(n=6),雌雄轮流育雏,育雏前、中期(雏鸟1~20d日龄),雌性育雏时间比雄性长,是雄性的2倍,育雏后期(雏鸟大于20 d日龄),... 相似文献
13.
14.
Mengyi Ba Ruonan Chen Qiuchen Huang Yanli Song Wen Li Yuanyuan Zhang Haixin Liu Xiang Xu Weidong Zhang Zhiqiang Cai Tao Sun 《化学与生物多样性》2023,20(8):e202300350
This work firstly reported a new polycaprolactone based material functionalized with guanidinium ionic liquid (PCL-GIL) as the stationary phase with high resolution performance for capillary gas chromatography (GC). It is composed of polycaprolactone (PCL) and guanidinium ionic liquid (GIL) with amphiphilic conformation. The PCL-GIL capillary column coated by static method exhibited high column efficiency of 3942 plates/m and moderate polarity. As a result, the PCL-GIL column exhibited high-resolution capability. For a mixture of 27 analytes with a wide ranging polarity and outperformed the PCL-2OH and HP-35 columns, showing its advantageous separation capability for analytes of diverse types. Moreover, the PCL-GIL column showed high resolving capability for various positional isomers and cis-/trans-isomers, including alkylbenzenes, chlorobenzenes, naphthalenes, bromonitrobenzenes, chloronitrobenzenes, benzaldehydes, phenols, alcohols, respectively. In a word, PCL derivatized by GIL units as a new type of stationary phase has a promising future in GC separations. 相似文献
15.
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
16.
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
17.
Relationships between the permeability coefficient (PHA) and partition coefficient (K
m/w) of acetic acid and the surface density of DMPC:cholesterol bilayers have been investigated. Permeability coefficients were measured in large unilamellar vesicles by NMR line broadening. Bilayer surface density, , was varied over a range of 0.5–0.9 by changing cholesterol concentration and temperature. The temperature dependence of PHA for acetic acid exhibits Arrhenius behavior with an average apparent activation energy (E
a
) of 22±3 kcal/mole over a cholesterol mole fraction range of 0.00–0.40. This value is much greater than the enthalpy change for acetic acid partitioning between bulk decane and water (H° = 4.8±0.8 kcal/mole) and the calculated E
a
(= 8.0 kcal/mole) assuming a bulk phase permeability model which includes the enthalpy of transfer from water to decane and the temperature dependence of acetic acid's diffusion coefficient in decane. These results suggest that dehydration, previously considered to be a dominant component, is a minor factor in determining E
a
. Values of 1n PHA decrease linearly with the normalized phospholipid surface density with a slope of = -12.4±1.1 (r = 0.90). Correction of PHA for those temperature effects considered to be independent of lipid chain order (i.e., enthalpy of transfer from water to decane and activation energy for diffusion in bulk hydrocarbon) yielded an improved correlation ( = -11.7±0.5 (r = 0.96)). The temperature dependence of Km/w is substantially smaller than that for PHA and dependent on cholesterol composition. Values of 1n Km/w decrease linearly with the surface density with a slope of = -4.6±0.3 (r = 0.95), which is 2.7-fold smaller than the slope of the plot of 1n PHA
vs. . Thus, chain ordering is a major determinant for molecular partitioning into and transport across lipid bilayers, regardless of whether it is varied by lipid composition or temperature.This work was supported by grants from Glaxo, INTERx/Merck, and University of Utah Research Committee. 相似文献
18.
杨树新品种叶肉原生质体培养和植株再生 总被引:4,自引:1,他引:3
从1 个月龄的NL-80106 杨(Populusdeltoides×P. sim onii)无菌苗叶片分离得到大量原生质体,纯化后其原生质体产量为4×107/g fr.w t. 纯化的原生质体在含2,4-D 2 m g/L、NAA 0.5 m g/L和KT 0.5 m g/L的KM8p 和MS培养基中进行高密度液体浅层培养,渗透势为0.40 m ol/L的KM8p 培养基中原生质体分裂频率最高. 培养第5 天观察到第一次细胞分裂,培养10 d 的分裂频率为4.5% ,12 周内可形成大量的细胞团和小愈伤组织. NL-80106杨叶肉原生质体在富含有机氮并以葡萄糖为碳源的培养基中具有较高的分裂频率和植板率.小愈伤组织在gelrite 固化的NLZ1 培养基上增殖生长,3 周后形成4—6 m m 结构紧密的鲜红色愈伤组织,转至NLF分化培养基,分化成苗率为100% . 待芽伸长到3 cm 时,从基部切下转至1/2 MS培养基上诱导生根,形成完整植株 相似文献
19.
Ola Fjellstrm Torbjrn Olausson Xiang Hu Bruno Kllebring Jan Rydstrm Suhail Ahmad Philip D. Bragg 《Proteins》1995,21(2):91-104
A three-dimensional structure of the NAD site of Escerichia coli transhydrogenase has been predicted. The model is based on analysis of conserved residues among the transhydrogenases from five different sources, homologies with enzymes using NAD as cofactors or substrates, hydrophilicity profiles, and secondary structure predictions. The present model supports the hypothesis that there is one binding site, located relatively close to the N-terminus of the α-subunit. The proposed structure spans residues α145 to α287, and it includes five β-strands and five α-helices oriented in a typical open twisted α/β conformation. The amino acid sequence following the GXGXXG dinucleotide binding consensus sequence (residues α172 to α177) correlates exactly to a typical fingerprint region for ADP binding βαβ folds in dinucleotide binding enzymes. In the model, aspartic acid α195 forms hydrogen bonds to one or both hydroxyl groups on the adenosine ribose sugar moiety. Threonine α196 and alanine α256, located at the end of βB and βD, respectively, create a hydrophobic sandwich with the adenine part of NAD buried inside. The nicotinamide part is located in a hydrophobic cleft between αA and βE. Mutagenesis work has been carried out in order to test the predicted model and to determine whether residues within this domain are important for proton pumping directly. All data support the predicted structure, and no residue crucial for proton pumping Was detected. Since no three-dimensional structure of transhydrogenase has been solved, a well based tertiary structure prediction is of great value for further experimental design in trying to elucidate the mechanism of the energy-linked proton pump. © 1995 Wiley-Liss, Inc. 相似文献
20.
Nuclear migration advances in fungi 总被引:11,自引:0,他引:11
Nuclear migration encompasses three areas: separation of daughter nuclei during mitosis, congress of parental nuclei before they fuse during fertilization, and positioning of nuclei in interphase cells. This review deals primarily with interphase nuclear migration, which is crucial for events as disparate as vertebrate embryonic development and growth of fungal mycelia. Mutants of Aspergillus nidulans, Neurospora crassa and Saccharomyces cerevisiae have been particularly informative, and a detailed molecular analysis of this process is now well under way. 相似文献