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981.
C Di Bello A Scatturin G D'Auria M Gargiulo L Paolillo E Trivellone R De Castiglione 《Biopolymers》1991,31(6):643-652
The conformational properties of spantide [(D-Arg, D-Trp, Leu) substance P] have been studied by fluorescence, CD, and nmr techniques. The fluorescence, CD, and nmr parameters in different solvents and in a micellar environment (SDS) are compared with the data collected for bombesin. A preliminary investigation on [D-Pro] spantide is also reported. 相似文献
982.
Modeling growth and succinoglucan production by Agrobacterium radiobacter NCIB 9042 in batch cultures 总被引:1,自引:0,他引:1
Wild-type Agrobacterium radiobacter NCIB 9042 has been cultivated in batch cultures on a synthetic medium which was adapted for growth and succinoglucan production. Experiments were carried out in a 4-L stirred-tank aerated reactor. Glucose, biomass, polysaccharide, protein, and inorganic- and organic-nitrogen concentrations were measured, and oxygen consumption and CO(2) production rates were obtained by a gas-balance technique. Nitrogen balance shows that inorganic nitrogen is entirely recovered into proteins. The carbon balance is satisfied with in +/-5%. Stoichiometric equations for biomass growth and succinoglucan synthesis were established. The biosyntheticpolymer pathways including ATP and cofactor consumption were investigated. From previous studies, a (P/O) value of 1.66 is selected for oxygen sufficient cultures. The actual ATP requirements of 25.4 mmol ATP/g succinoglucan (38.5 mol ATP/mol succinoglucan), determined by a metabolic analysis, is 2.39 times the stoichiometric value. Experimental results were modeled by a system of differential equations. The exponential growth phase was described by a nitrogen-limited Monod equation. Subsequent succinoglucan synthesis followed a slightly modified Luedeking-Piret relation partitioning internal and external polysaccharide. Experimentally determined coefficients are compared with published results for continuous culture of A. radiobacter NCIB 11883. 相似文献
983.
Henrika G. M. Tiedink Laura H. J. De Haan Wim M. F. Jongen Jan H. Koeman 《Cell biology and toxicology》1991,7(4):371-386
4-chloro-methoxyindole is a naturally occurring compound in Vicia faba which can easily react with nitrite to form a N-nitroso compound. In this in vitro study, the potential genotoxic effects of nitrosated 4-chloro-6-methoxyindole and its structural analogue 4-chloroindole were evaluated for the first time by using both Salmonella and Chinese hamster V79 cells. Additionally, the inhibition of gap junctional intercellular communication in V79 cells by these compounds was determined; this is a validated parameter for tumor-promoting activity. Most assays were also performed with nitrosated indole-3-acetonitrile, a naturally occurring compound in brassicas. Both nitrosated chloroindoles were highly mutagenic to Salmonella typhimurium TA100 without the need of exogenous metabolic activation and were potent inducers of Sister Chromatid Exchanges. Nitrosated indole-3-acetonitrile generated the same effects, although at much higher concentrations. Equivocal results were obtained for the nitrosated chloroindoles in a forward mutation assay using the hypoxanthine guaninephosphoribosyltransferase locus. All nitrosated indole compounds significantly inhibited gap junctional intercellular communication. These results indicate that nitrosated chloroindoles and nitrosated indole-3-acetonitrile should be considered as mutagens and agents with potential tumor-promoting capacity.Abbreviations BrdU
5-bromo-2-deoxyuridine
- 4Cl
4-chloroindole
- 4C6MI
4-chloro-6-methoxy-indole
- DMSO
dimethyl sulfoxide
- EBSS
Earle's balanced salt solution
- EMS
ethyl methanesulfonate
- GJIC
gap junctional intercellular communication
- HBSS
Hanks balanced salt solution
- HGPRT
hypoxanthine guaninephosphoribosyl transferase
- I3A
indole-3-acetonitrile
- MNNG
1-methyl-1-nitroso-3-nitroguanidine
- NOC
N-nitroso compounds
- NQO
4-nitroquinolone-N-oxide
- SCE
sister chromatid exchange
- 6TG
6-thioguanine
- TPA
12-O-tetradecanoylphorbol-13-acetate 相似文献
984.
Extension of the range of recognition sequences for triple helix formation by oligonucleotides containing guanines and thymines. 总被引:11,自引:0,他引:11
J S Sun T De Bizemont G Duval-Valentin T Montenay-Garestier C Hélène 《Comptes rendus de l'Académie des sciences. Série III, Sciences de la vie》1991,313(13):585-590
Oligodeoxynucleotides containing G and T can bind to homopurine.homopyrimidine sequences on double-stranded DNA by forming C.G x G and T.A x T base triplets. The orientation of the third strand in such triple helices depends on the number of GpT and TpG steps. Therefore a single oligonucleotide can be designed to bind to two consecutive homopurine.homopyrimidine sequences where the two homopurine stretches alternate on the two strands of DNA. The oligonucleotide switches from one homopurine strand to the other at the junction between the two sequences. This result shows that it is possible to extend the range of DNA sequences that can be recognized by a single oligonucleotide. 相似文献
985.
986.
Developmental expression of rat cardiac troponin I mRNA 总被引:4,自引:0,他引:4
S Ausoni C De Nardi P Moretti L Gorza S Schiaffino 《Development (Cambridge, England)》1991,112(4):1041-1051
987.
The North Sea, one of the most productive of the earth's seas and oceans, is also surrounded by some of earth's most densely
populated and heavily industrialized regions. A growing number of signals are being received which indicate that this valuable
ecosystem is increasingly under stress. This has generated a corresponding increase in concern over the steps to be taken
to protect the North Sea. While there are divergent views on what constitutes an ‘ideal’ North Sea, there is a general recognition
that any decisions that are made should be based on a good understanding of this ecosystem. The intention of this paper is
to give an overview of what is presently known, and to identify areas where more studies are needed. A brief summary of the
hydrography and the biota of the North Sea is given. Biotic and abiotic structure justify partitioning the North Sea into
three ecologically different regions: southern, central, and northern. For the most part, neither the top predators,e.g. marine birds and mammals, nor the macroalgae and sea grasses are included in this overview. 相似文献
988.
989.
990.