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41.
Summary With the aim of comparing the primary structures of gene products coded for by T-even bacteriophages we constructed clone libraries of the DNAs of bacteriophages T2 and T6. Using hybrid M13 phages carrying the gene for the T4-coded -glucosyl transferase (gt) we isolated corresponding T2 and T6 clones. The nucleotide sequences of the three gt genes and the amino acid sequences derived were compared. The differences between the genes and their products are discussed in terms of structure, function and evolutionary aspects.Abbreviations bp
base pair
- gt
glucosyl transferase
- HMC
5-hydroxymethyl cytosine
- orf
open reading frame
- Xgal
5-bromo-4-chloro-3-indolyl--d-galactoside 相似文献
42.
Mona J. Law Gladys E. Deibler Russell E. Martenson Henry C. Krutzsch 《Journal of neurochemistry》1985,45(4):1232-1243
Rabbit myelin basic protein (BP) was subjected to partial cleavage with plasmin, and 15 cleavage products were isolated by a combination of gel filtration and ion-exchange chromatography. Their identification was achieved by amino acid analysis and tryptic peptide mapping, supplemented in some instances by carboxy-terminal analyses with carboxypeptidases A, B, and Y and amino-terminal analyses with dipeptidyl aminopeptidase I. The results showed that major plasmic cleavage sites included the Lys89-Asn90, Lys133-Ser134, and Lys153-Leu154 bonds. Cleavages also occurred at the Arg31-His32, Lys53-Arg54, and Arg25-His26 bonds, but these appeared to be less extensive. A large number of additional peptides were produced in relatively low yield. The smaller of these were isolated from heterogeneous fractions by high-voltage electrophoresis-TLC. Amino acid analysis of these peptides showed that minor cleavage sites included the Arg9-His10, Lys13-Tyr14, Lys103-Gly104, Lys137-Gly138, Lys140-Gly141, and Arg160-Ser161 bonds. In spite of a lower selectivity toward peptide bonds in BP as compared with pepsin, cathepsin D, and thrombin, plasmin has the advantage over the former proteinases in that it does not cleave at or near the Phe44-Phe45 bond. Instead it cleaves at the Arg31-His32 and Lys53-Arg54 bonds, thus preserving the entire hydrophobic sequence Ile-Leu-Asp-Ser-Ile-Gly-Arg-Phe-Phe as well as short sequences to either side. 相似文献
43.
Efficient selection intensity in early generation index selection in groundnut (Arachis hypogaea L.)
A. Bandyopadhyay V. Arunachalam K. Venkaiah 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1985,71(2):300-304
Summary The F2 potential of single and three-way crosses was evaluated using a set of physiological and yield components. Results were based on an index of selection using (a) only yield components and (b) both physiological and yield components. The indices were constructed using the percentage improvement of F2 over the better parent of the corresponding F1 cross for every character. The performance of F2 plants assessed by the expected value of the regression index was ranked in descending order to provide a ranked F2 distribution (FRD). The FRD was divided into four equal parts, T25 (top 25%), T50 (26–50%), T75 (51–75%) and T100 (76–100%). F3 families derived from F2 plants in T25 were found to provide a higher frequency of selections for pod number than T50, T75 and T100. The frequency of selections was higher in three-way than single crosses. Selection index based on physiological and yield components was more efficient in trapping F2 plants providing selections in F3 than the index based on yield components only. The results brought out the importance of bunch x bunch crosses as a complement to the usually advocated bunch x runner ones. 相似文献
44.
Restriction endonuclease EcoO109 from Escherichia coli H709c with heptanucleotide recognition site 5'-PuG/GNCCPy 总被引:1,自引:0,他引:1
A new restriction endonuclease, EcoO109, has been isolated from Escherichia coli H709c by polyethyleneimine (PEI) precipitation, DEAE-cellulose chromatography and heparin agarose chromatography. The yield was high, more than 3000 units/g of wet cells. The EcoO109 endonuclease recognizes and cleaves a nucleotide sequence of (formula: see text), in the presence of 10 mM Mg2+. The enzyme will be useful for structural analysis and molecular cloning of DNA because of the stability, high yield and easy handling of the producer strain. 相似文献
45.
Probabilistic models of the cell cycle maintain that cell generation time is a random variable given by some distribution function, and that the probability of cell division per unit time is a function only of cell age (and not, for instance, of cell size). Given the probability density, f(t), for time spent in the random compartment of the cell cycle, we derive a recursion relation for
n(x), the probability density for cell size at birth in a sample of cells in generation n. For the case of exponential growth of cells, the recursion relation has no steady-state solution. For the case of linear cell growth, we show that there exists a unique, globally asymptotically stable, steady-state birth size distribution,
*(x). For the special case of the transition probability model, we display
*(x) explicitly.This work was supported by the National Science Foundation under grants MCS8301104 (to J.J.T.) and MCS8300559 (to K.B.H.), and by the National Institutes of Health under grant GM27629 (to J.J.T.). 相似文献
46.
Characterization of Cholecystokinin from the Human Brain 总被引:1,自引:0,他引:1
Laurence J. Miller Ian Jardine† Edward Weissman Vay Liang W. Go David Speicher‡ 《Journal of neurochemistry》1984,43(3):835-840
Human forms of cholecystokinin have not previously been characterized chemically. In this study, we have extracted and purified the predominant molecular form of cholecystokinin present in human cerebral cortex. The peptide was characterized by amino acid analysis, automated peptide sequencing, and fast atom bombardment mass spectrometry. It appears to be identical to porcine cholecystokinin-octapeptide, with the sequence of Asp-Tyr(SO3)-Met-Gly-Trp-Met-Asp-Phe(NH2). This structural identity is consistent with the observations that the peptide in human brain and porcine cholecystokinin-octapeptide are recognized similarly by a battery of antisera to porcine cholecystokinin; that they coelute from several chromatographic systems, including gel filtration, ion exchange, and reversed-phase; and that they possess similar biological activities. 相似文献
47.
48.
Nonspiking interneurons were investigated in a tethered, walking insect, Carausius morosus, that was able to freely perform walking movements. Experiments were carried out with animals walking on a lightweight, double-wheel treadmill. Although the animal was opened dorsally, the walking system was left intact. Intracellular recordings were obtained from the dorsal posterior neuropil of the mesothoracic ganglion. Nonspiking inter-neurons, in which modulations of the membrane potential were correlated with the walking rhythm, were described physiologically and stained with Lucifer Yellow. Interneurons are demonstrated in which membrane potential oscillations mirror the leg position or show correlation with the motoneuronal activity of the protractor and retractor coxae muscles during walking. Other interneurons showed distinct hyperpolarizations at certain important trigger points in the step cycle, for example, at the extreme posterior position. Through electrical stimulation of single, nonspiking interneurons during walking, the motoneuronal activity in two antagonistic muscles—protractor and retractor coxae—could be reversed and even the movement of the ipsilateral leg could be influenced. The nonspiking interneurons described appear to be important premotor elements involved in walking. They receive, integrate, and process information from different leg proprioceptors and drive groups of leg motoneurons during walking. 相似文献
49.
Ariyuki Kagaya Yosuke Uchitomi Akira Kugaya Minoru Takebayashi Ikuo Nagaoka Mitsutaro Muraoka Norio Yokota Shigeto Yamawaki 《Journal of neurochemistry》1996,66(4):1483-1488
Abstract: We investigated the rapid and slow effects of NaF on intracellular signaling systems such as Ca2+ homeostasis and cyclic GMP (cGMP) generation in rat glioma C6 cells, using the Ca2+ -sensitive dye fura-2 and cGMP enzyme immunoassay. We found that the following: (a) NaF enhanced cGMP generation in a concentration-dependent manner. This enhancement was abolished by pretreatment with 100 µ M BAPTA tetraacetoxymethyl ester or in the presence of W-7 in a concentration-dependent manner. N G -Monomethyl- l -arginine (NMMA), a competitive inhibitor of nitric oxide synthase (NOS), also inhibited the NaF-induced generation of cGMP. These results suggest that NaF-induced cGMP generation occurs via a calcium/calmodulin- and NOS-dependent pathway. (b) The basal intracellular Ca2+ concentration ([Ca2+ ]i ) was transiently greater at 1 and 3 h after pretreatment with NaF. W-7 and W-13 antagonized the increase in [Ca2+ ]i , whereas NMMA had little effect. This suggests that the NaF-induced change in basal [Ca2+ ]i was mediated by a calmodulin-dependent pathway but was independent of a NOS-sensitive pathway. (c) The serotonin (5-HT)-induced intracellular mobilization of Ca2+ was reduced by pretreating the cells with NaF. The reduction in Ca2+ mobilization was antagonized by genistein, a tyrosine kinase inhibitor. W-7, W-5, and H-8 had no effect. Results suggest that NaF differentially regulates the cGMP generation, basal [Ca2+ ]i , and 5-HT2A receptor function in C6 glioma cells. 相似文献
50.
A note on optimality in lattice square designs 总被引:1,自引:0,他引:1