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Journal of Ichthyology - Gonadal structure, cytological condition of oocytes, ultrastructure of egg envelope, and spermatozoa morphology are studied in the individuals of Inimicus sinensis... 相似文献
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D. A. Gordenin M. V. Trofimova O. N. Shaburova Y. I. Pavlov Y. O. Chernoff Y. V. Chekuolene Y. Y. Proscyavichus K. V. Sasnauskas A. A. Janulaitis 《Molecular & general genetics : MGG》1988,213(2-3):388-393
Summary We have demonstrated that precise excision of bacterial transposon Tn5 can occur in the yeast, Saccharomyces cerevisiae. Tn5 insertions in the yeast gene LYS2 were generated by transposon mutagenesis made in Escherichia coli by means of a ::Tn5 vector. Nine insertions of Tn5 into the structural part of the yeast LYS2 gene situated in a shuttle epsiomal plasmid were selected. All the plasmids with a Tn5 insertion were used to transform yeast strains carrying a deletion of the entire LYS2 gene or a deletion of the part of LYS2 overlapping the point of insertion.All insertions inactivated the LYS2 gene and were able to revert with low (about 10-8) frequencies to lysine prototrophy. Restriction analysis of revertant plasmids revealed them to be indistinguishable from the original plasmid without Tn5 insertion. DNA sequencing of the regions containing the points of insertions, made for two revertants, proved that Tn5 excision was completely precise. 相似文献
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Victor N. Mikheev Dmitry S. Pavlov Daria Pakulska 《Environmental Biology of Fishes》1992,35(4):351-360
Synopsis Swimming speed and swimming path of goldfish and tetra larvae were studied in aquaria containing food patches composed of decapsulated cysts and immobilized nauplii of Artemia salina or sparsely distributed prey. The mean swimming speed of starved larvae in the medium without food was about four times higher than the speed of larvae feeding in a patch. Satiated larvae swam about 1.5 times slower than hungry fish. Consumption of single prey items by starved larvae caused the following sequence of swimming responses: handling pause (cessation of swimming), slow swimming in a restricted area, and fast swimming (approximately twice as fast as hungry larvae before encountering food) accompanied by a widening of the area searched (area increased searching). Mean swimming speed was constant over a broad range (101–103 ind·1–1 of food density, although at extreme (high or low) values of food density it depended on swimming responses of the predator. Frequency of visits to the different parts of the aquarium strongly depended on encounters of hungry fish with food particles or patches. 相似文献
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正常小鼠高频心电图时域值和功率谱的研究 总被引:5,自引:1,他引:4
本文用南京新博公司生产的NHE-1000型心电高频信息检测分析仪研究了正常小鼠(昆明种)高频心电图(HF-ECG)的时域值和QRS波群的功率谱。主要结果如下(以正导为例,-X±SD):心率603±88次/min(n=74);P-R间期相对较长。为34.9±4.7ms(n=58),占心动周期的34.9±4.9%,这与人类有很大的不同;QRS波宽9.2±1.2ms,占心动周期的9.2±1.4%(n=74),这一结果与以前的文献报道相差较大。T波宽10.3±3.2ms,占心动周期的10.3±3.2%;Q-T间期19.4±3.2ms,占心动周期的19.5±3.6%;QRS波群峰-峰值(Vp-p)为1.456±0.480mV;T波高0.336±0.115mV;73只动物Ⅱ导联高频切迹总数只有3个,扭挫26个。Ⅱ导联QRS波群的功率谱特点:0—80Hz的相对能量为45.48±15.32%;80—200Hz为43.97±9.95%;200—300Hz为8.89±7.38%;300—1000Hz为1.66±2.74%。 相似文献
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Production of phosphomonoesterases by Nicotiana tabacum 1507 in an aqueous two-phase system 总被引:1,自引:0,他引:1
Ilieva MP Bakalova A Mihneva M Pavlov A Dolapchiev L 《Biotechnology and bioengineering》1996,51(4):488-493
Studies were conducted on Nicotiana tabacum 1507 cultivation in an aqueous two-phase system (PD(5)) formed by adding 4% PEG (MW 20,000) and 7.5% dextran (MW 70,000) to the medium. The time course of growth and changes in the phase volumes of the PD(5) system, as well as the biosynthesis, secretion, and partitioning of phosphomonoesterases during 11 days of cultivation, were followed. In comparison with N. tabacum 1507 cultivation as a free suspension, on day 8 of cultivation in the PD(5) system the yields of acid and alkaline extracellular phosphomonoesterases were 18 and 10 times higher, respectively. Partitioning took place mainly in the bottom phase with specific activity being 4.5 and 3.5 times higher, respectively. (c) 1996 John Wiley & Sons, Inc. 相似文献
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The fidelity of the human leading and lagging strand DNA replication apparatus with 8-oxodeoxyguanosine triphosphate. 下载免费PDF全文
A product of oxidative metabolism, 8-oxodeoxyguanosine triphosphate (8-O-dGTP), readily pairs with adenine during DNA replication, ultimately causing A.T-->C.G transversions. This study utilized 8-O-dGTP as a probe to examine the fidelity of the leading and lagging strand replication apparatus in extracts of HeLa cells. Simian virus (SV) 40 T antigen-dependent DNA replication reactions were performed with two M13mp2 vectors with the SV40 origin located on opposite sides of the lacZ alpha sequence used to score replication errors. The presence of 8-O-dGTP at equimolar concentration with each of the 4 normal dNTPs resulted in a > 46-fold increase in error rate for A.T-->C.G transversion over that observed in the absence of 8-O-dGTP. A similar average error rate was observed on the (+) and (-) strands in both vectors, suggesting that the fidelity of replication by leading and lagging strand replication proteins is similar for the dA.8-O-dGMP mispair. Replication fidelity in the presence of 8-O-dGTP was reduced on both strands when an inhibitor of exonucleolytic proofreading (dGMP) was added to the reaction. These data suggest that the majority of dA.8-O-dGMP mispairs are proofread by both leading and lagging strand replication proteins. 相似文献
9.
Georges M. Pavlov Evguenija V. Korneeva Natalia P. Yevlampieva 《International journal of biological macromolecules》1994,16(6):318-323
The hydrodynamic characteristics of the polysaccharide pullulan (polymaltotriose) in water have been investigated and its molecular characteristics have been determined. Experimental values varied over the following ranges: velocity sedimentation coefficient (S): 0.9 < S < 11.2, translational diffusion coefficient (107 cm2 s−1): 1.1 < D < 14.7 and intrinsic viscosity (cm3 g−1): 6.7 < [η] < 164, which corresponds to a change in molecular weight (× 103) in the range 3.9 < MSD < 644. On the basis of analysis of the literature and our experimental data, excluded volume effects have been shown to have a prevailing influence on the chain length of these polysaccharides. The equilibrium rigidity and hydrodynamic chain diameter of pullulan were evaluated on the basis of the theory of hydrodynamic properties of a wormlike necklace, taking into account excluded volume effects. At low M (< 30 × 103) the translation friction data (in contrast to viscometric data) cannot be described in the framework of the theory of linear molecules. 相似文献