Library

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • 2025-2025
  • 2010-2014
  • 1995-1999
  • 1980-1984  (60)
  • 1975-1979  (148)
  • 1965-1969
  • 1945-1949
  • 1940-1944
  • 1850-1859
  • 1840-1849
  • 1830-1839
  • 1986
  • 1982  (60)
  • 1979  (148)
  • 1945
  • 1943
  • 1852
  • 1839
  • 1816
  • Life Sciences  (208)
Material
Years
  • 2025-2025
  • 2010-2014
  • 1995-1999
  • 1980-1984  (60)
  • 1975-1979  (148)
  • +
Year
  • 1
    Electronic Resource
    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 2 (1982), S. 42-42 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 2
    Electronic Resource
    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 2 (1982), S. 51-58 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: This paper considers techniques of measurement of the curves of oxygen consumption by microorganisms. The widely applied method of obtaining the value of the critical oxygen concentration (COC) using these curves has been analysed. The experimental conditions necessary for the adequate measurement of the culture respiration rate in a fermenter have been found. It has been shown that in the case when the respiration rate within the considered range of pO2 is determined by one and the same enzyme, the COC value is not an apropriate characteristic of the mode of the respiration rate dependence on oxygen concentration.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 3
    Electronic Resource
    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 2 (1982), S. 192-192 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 4
    Electronic Resource
    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 2 (1982), S. 187-191 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Rabbit liver microsomal cytochrome P-450 was immobilized by entrapment in calcium alginate gel. Aminopyrine demethylation experiments showed that the immobilized enzyme system is highly active and exhibits an unimpaired functional stability as compared with crude microsomes. The alginate entrapped microsomes were employed in a fixed bed recirculation reactor, where aminopyrine was continuously demethylated. Such model enzyme reactor can be a useful tool for studying extracorporeal drug detoxification or preparative substrate conversion with microsomal enzyme systems.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 5
    Electronic Resource
    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 2 (1982) 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 6
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: The zone reader of the Autoselect-system enables to measure the 64 inhibition zones of a quadratic bioassay plate with an accuracy of 0,1 mm within 3 minutes. A carriage moves each zone in the light beam. With a special photometrical device 3 defined areas of the inhibition zone can be measured quantitatively by 2 receivers. The indicated values of the diameters result from the analog treatment of the signals. By coupling to a computer the datas of the measuring and other desired informations are printed out.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 7
    Electronic Resource
    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 2 (1982), S. 199-204 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: The advantages of the Autoselect-system are explained. They are offered by a higher speed of all manipulations, by a significantly better accuracy, by getting more informations and by easier physical labour. In the most cases the automated work can be done in a fourth till a tenth of the time needed for manual handlings. The capacity of the machines amounts 5 000 to 30 000 colonies/samples per day. Special problems as well as possibilities for a further increase of the efficiency are discussed.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 8
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: The Supreme Court of the US in 1980 granted a patent for a strain of Pseudomonas containing two plasmides after genetic manipulation. This is the first case of patenting a living organism. Whereas the patent law of US and of many other countries further more on supports the principle that natural products are not patentable man-made microorganisms on the other hand fullfil very important crucials of patentability as far as they are new, unobvious, reproducible and useful. The situation arising as the result of this decision is described and the implications and consequenses for the patent law, the taxonomy and the general biological thought are discussed.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 9
    Electronic Resource
    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 2 (1982), S. 226-226 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 10
    Electronic Resource
    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 2 (1982), S. 213-225 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: The kinetics of assimilation of hydrocarbons having a different structure by Candida yeasts was studied.The rates of oxidation of various carbon atoms in the molecules of isoalkanes, alkylaromatic hydrocarbons and n-alkanes were evaluated in the range of C11 to C28.Metabolic inhomogeneity of carbon atoms in the molecules of isolakanes and alkylaromatic hydrocarbons was observed. A competition in the assimilation of the called hydrocarbons and n-alkanes and also a competition in the assimilation of n-alkanes of a different molecular weight, i.e. metabolic inhomogeneity of carbon atoms of n-dodecane and n-tetracosane was found out for yeasts.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 11
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Understanding both the qualitative and quantitative transient responses to inlet flow and substrate step functions has been a relatively unsolved problem for continuous fermentation processes. This study of transient responses and simple descriptive models suggests that the saturation constant of the MONOD equation is a variable. Thatf variable depends on the rate constants of parallel biochemical pathways leading to cell growth, the concentration of cells themselves, and the concentration of all products in the culture. Mechanisms for describing the hysteresis behavior of the growth rate funcion are postulated in terms of the underlying molecular biology of the microbial system.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 12
    Electronic Resource
    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 2 (1982), S. 239-249 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: For several years now, we can notice efforts in increasing the efficiency of microbial processes by means of more intensive scientific investigation of such processes. Essential prerequisites to it are improved possibilities for process monitoring (available sensors) as well as facilities for realtime processing of process information. In this paper a microcomputer system is represented, which has been constructed on the base of computing needs for fermentation. The computing needs for fermentation experiments are outlined and the structure of the microcomputer is described. As an example it is illustrated what tasks can be solved by this microcomputer in coupled operation with a laboratory fermentor.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 13
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 14
    Electronic Resource
    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 2 (1982), S. 251-262 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: The industrial continuous fermentation for the production of microbial protein is like any real process subject to disturbances. The considerable social expenditures involved in production make it necessary to restrict the negative consequences of these disturbances to a minimum by means of suitable measures. One such measure is the computer-aided adaptation of the static optimum. For the reaction on nonmeasurable disturbing inputs an algorithm is given containing the steps data filtering, adaption of process model and optimization, and the solution of the data-filtering problem in the widest sense by spline functions is discussed. The application of this algorithm to a specific problem of process control is demonstrated in [1].
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 15
    Electronic Resource
    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 2 (1982), S. 263-274 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: The influence of technological variables on the cell disintegration of yeast suspensions by means of a ball mill and a high pressure homogenizer has been studied by measuring the electrical conductivity. The rate constants and half-life periods are calculated. Regarding the production of protein isolates, the stipulation of optimal disintegration conditions requires a compromise between a degree of disruption as high as possible and a low destruction of the cell walls.By homogenizing, fragments of cell walls arise which are more uniform and better separable in comparison with the milling process. Therefore the mechanical breakage of yeast cells on a large scale should be carried out by the use of high pressure homogenizers.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 16
    Electronic Resource
    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 2 (1982), S. 297-298 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 17
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Starting from cotton linters cellulose modified in physical structure type of lattice, degree of order, state of swelling by different pretreatments, and from culture filtrates of Gliocladium spec., the initial stage of enzymatic hydrolysis of cellulose has been investigated. Especially with substrates of high degradability a considerable effect of stirring on rate of formation of soluble products was found. For linerization of yield-vs-time-curves (% residue resp. 7percnt; solubles as a criterion for yield), a 2-parameatric first order rate law was found to be suitable within a limited time interval, values of k1 were higher and for the accessible part of the substrate were lower in the initial stage of hydrolysis than in the later one. The MICHAELIS-MENTEN-constant kM has been determined for substrates of different physical structure after different times of reaction. Data found for kM indicated a stronger dependence of kM on reaction time than on physical structure of the substrate under conditions applied.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 18
    Electronic Resource
    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 2 (1982), S. 299-302 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: The empirical determined constant of 3.14 gram biomass per available electron is a good base for the calculation of minimum substrate consumption coefficients in the aerobic fermentation of paraffins by yeasts.The analysis of experimental determined specific substrate consumption coefficients and their comparison with the corresponding theoretical values show that the theoretical ones can be reached only if the substrate composition referring to carbon and hydrogen is of optimal composition for all syntheses.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 19
    Electronic Resource
    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 2 (1982) 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 20
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 21
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 22
    Electronic Resource
    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 2 (1982), S. 369-375 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: The biotin activity of beet and lactose molasses against the test strain Saccharomyces cerevisiae 225 by auxanographic method was evaluated. The level of lactose molasses biotin activity is almost twice as high as that obtained in the case of beet molasses. The results of bioautography with test strains Saccharomyces cerevisiae 225 and Lactobacillus arabinosus 17-5 indicate the qualitative composition of biotin derivatives (vitamers) in both molasses. Depending on the various technological steps e.g. sterilization or clarification one may find differences in the content and qualitative composition of biotin vitamers.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 23
    Electronic Resource
    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 2 (1982) 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 24
    Electronic Resource
    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 2 (1982), S. 3-41 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: In this review the state of the art in animal cell technology, using suspension culture techniques is updated as far as the end of 1980. We have tried to discuss, on a broad basis, the current status and potential developments of both, the purely biological and the biochemical engineering aspects which may be important to improve the performance and design of animal cell technologies. The process economics could be considerably improved by the use of transformed animal cell substrates, the use of cheaper cultivation media and by methodological and engineering means. Most of these aspects are in the state of realization. Nevertheless, for a great variety of biological active substances which do not require so - or posttranslational processing, recombinant DNA-techniques (e.g. genetic engineering) are a promising alternative for the production of animal cell derived substances.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 25
    Electronic Resource
    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 2 (1982), S. 72-72 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 26
    Electronic Resource
    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 2 (1982), S. 78-78 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 27
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 28
    Electronic Resource
    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 2 (1982), S. 87-94 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: An enzyme being able to hydrolize the imido linkage at the N-terminal end of proline is isolated from E. coli B. This fact corresponds to the specifity of hydrolization of the animal prolidase. Enzyme synthesis within the cells of E. coli B is carried out independently from growth. Changed environmental factors may influence the formation rate of enzyme in a restricted way. A relatively high enzyme biosynthesis can be reached by cultivating the strain E. coli B at a temperature of 37°C as well as an initial pH-value of the medium of 7.0 in submerged culture (400-500 rpm) By variation of the medium composition enzyme synthesis does not change considerably, however, biomass yield can be increased about 100% If mechanical cell desintegration is optimized by means of ultrasonic or vibration homogenisator the cell components may be easily released with a higher proline specific activity as animal prolidase.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 29
    Electronic Resource
    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 2 (1982), S. 114-114 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 30
    Electronic Resource
    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 2 (1982), S. 115-115 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 31
    Electronic Resource
    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 2 (1982), S. 116-116 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 32
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Catabolic pathways of long-chain n-alkanes in the range of C8 to C18 are demonstrated and results of investigation about the regulation of monoterminal oxidation are given: - Enzymes of monoterminal alkane oxidation usually are inducible- Several intermediates of alkane oxidation can inhibit the primary oxidation of concerned alkane-Substances, e.g. glucose and glycerol, which ordinary don't be developed in catabolic alkane reactions, in many cases have an inhibitory effect on alkane oxidationThe regulation of catabolic pathways has a great influence on the formation of specific products This influence is demonstrated examplarily at the production of biotin, fatty acids and citric acid.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 33
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Most mathematical models for describing the physiological state in fermentations lead to solutions of the so-called “stiff differential systems” during simulation on a digital computerThere is no suitable conventional software for solving these systemsAs a result of a relatively extensive screening of suitable methods for the solution of “stiff” differential systems (about 200 methods) it may be concluded that the semiimplicit RUNGE-KUTTA-formulas of the ROSENBROCK type, which constitute a part of the collection of programmes STIFFSOLVER-80, are optimal for the simulation of fermentation processesFor determining kinetic parameters from integral data the authors use the system of programmes BIOKINTheir practical application is discussed for 3 examples: 1Growth of the yeast Saccharomyces cerevisiae and changes in the content of specific compounds (proteins and ergosterol)2Quantitative evaluation of “;direct oxygen transfer” in the submerged culture.3Biosynthesis of a new antibiotic substance mucidin.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 34
    Electronic Resource
    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 2 (1982), S. 178-178 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 35
    Electronic Resource
    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 2 (1982), S. 179-185 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: The enzymatic hydrolysis of cellobiose, an important intermediate of the decomposition of cellulose containing materials, with immobilized β-glucosidase preparations from Geotrichium candidum, Trichoderma lignorum and Aspergillus foetidus was examinedAt first it was the aim to prepare from differently purified samples with different specific cellobiase activities high active preparations on the basis of the inorganic carrier Silochrom S-80. Characteristics e.g. thermal stability and temperature and pH optimum of immobilized preparations were compared with those of soluble preparationsKinetics of cellobiose hydrolysis by immobilized enzyme preparations were studied.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 36
    Electronic Resource
    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 2 (1982), S. 43-50 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Floc formation, especially the influence of floe diameter variations on the total velocity of the process, was investigated in aerobic growth processes of yeast on the hydrocarbons of crude oil.The experimental results show that the diameter of the flocs is a function of the rheological properties of the fluids and the flow conditions.The floc diameter varies between 0,1 mm and a few millimeters. About 90% of the total yeast cells are situated in the interior of the flocs.Since oxygen must be transferred to all yeast cells their oxygen supply was studied.Thus, the yeast cells in the floc interior were not sufficiently supplied with oxygen, if the floc diameter reached a critical value.In such cases a decrease of the biomass formation rate was observed, although the dissolved oxygen concentration of the aquaeous fermentation medium was greater than zero. Therefore, aerobic microbial growth processes in multicomponent systems must be carried out without floc formation or under such conditions as cause very small floc diameters.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 37
    Electronic Resource
    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 2 (1982), S. 59-71 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: There are described possibilities of scale up in stirred tank fermenters being based on known relations of mass-, energy-and heat transfer. The represented mathematical description shows the problems of the necessary scale up in the practice with the theory of similarity in the stirred tank fermenter. Relating on the method of RUSHTON for calculation of the energy capacity in different stirred fermenters the influence of the aeration is examined and confirmed with experimental results of the author. By the sysem of equations the known parameters of the aerobic fermenters can be calculated.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 38
    Electronic Resource
    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 2 (1982), S. 73-77 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: The aim of the technological treatment of microbial processes is the optimal working of the production plant. The treatment itself is to be seen as a process whose realization requires a certain amount of expenditure. The problem of optimization of this process can with certain restictions be approximately solved in a series of steps. After a general formulation of the problem explanations are given for two important and typical steps - the determination of the extend of modelling and the choice of production cultures.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 39
    Electronic Resource
    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 2 (1982), S. 79-85 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: L-lysine synthesis pathway enzyme activities: β-aspartate kinase (EC.2.7.2.4), diaminopimelate decarboxylase (EC.4.1.1.20) for two L-lysine producing strains Brevibacterium flavum 22LD and RC-115 were studied. It has been found that β-aspartate kinase and diaminopimelate decarboxylase in the Br. flavum RC-115 are less sensitive to feed-back inhibition by lysine and threonine. It is supposed that desensitized β-aspartate kinase in the Br. flavum RC-115 can be determined by genetical changes of the regulatory properties of the β-aspartate kinase.Auxotrophity in the locus of homoserine dehydrogenase was tested and no homoserine dehydrogenase (EC.1.1.1.3) activity was found in either strain.The combination of these both types of mutation supplemented by the lack of catabolic repression in the RC-115 strain makes it an active lysine producer in the medium with high carbohydrates content.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 40
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Growing conditions have been found out for the bacterium Arthrobacter GJM-I to produce a lytic enzyme system, which converts cells of the yeast Candida spec. H to protoplasts quickly and in a good yield. Estimating the activities of α-mannanase and β-glucanase we found out the optimal culture time to gain the lytic enzyme system from the culture filtrate. It was shown that radioactive labeling of the yeast cells makes it possible to estimate quantitatively the conversion to protoplasts and the simultaneous lysis. The obtained lytic enzyme system can substitute the snail cnzyme system which was used for cell conversion of Candida spec. H to protoplasts till now.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 41
    Electronic Resource
    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 2 (1982), S. 103-106 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: The reaction between glucose and methylene blue, catalyzed by glucose oxidase (GOD)was analysed calorimetrically.The amount of heat produced under saturating methylene blue concentrations ( 〉 10-2 mol/1)was measured with glucose concentration and time as parameters (kinetic procedure) Kinetic constants (pseudo one substrate kinetics) were derived from the experimental data: KM(glucose)= 1.18 × 10-3 mol/l and Vmax = 0.085 J/mg GOD min (3.89 · 10-6 mol/mg GOD min)Comparison of caloric with optical measurements gave an enthalpy of reaction of 22.52 kJ/mol. Considering the observed substrate inhibition, glucose determinations are possible up to glucose concentrations of 0.1 mol/l.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 42
    Electronic Resource
    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 2 (1982), S. 307-315 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Thirteen isolates ofZymomonas were analyzed for their ability to tolerate increasing concentrations of glucose and ethanol. In medium containing 5.0% (v/v) ethanol, four isolates grew well in 15.0% (w/v) glucose. Six cultures tolerated at least 6,0% ethanol. Of all the isolates, 7 preferred glucose and 4 preferred sucrose as a sugar substrate. In a nutrient medium containing mineral salts and high concentrations of pantothenate and biotin ethanol production for 2 isolates was approximately 7.0%. Continuous stirring and growth factors were responsible for this increased ethanol production.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 43
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: The growth limitation of aerobic yeast cultures in the majority of cases involves a deep conversion of the metabolism and high changes in the functional state of the cellsThe excretion of metabolits as one of this changes of great importance and the other variations in the state of the cells are the consequence of functional alternations of several anabolic and catabolic processes.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 44
    Electronic Resource
    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 2 (1982), S. 325-330 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: It has been developed a model for a continuous working enzyme-reactor to determine the deviation of temperature and concentration in axial and radial direction. It's based on Partial Differential Equations for mass and enthalpy transfer. The model regards the specialities of kinetics of enzyme-catalytic processes with respect to the reaction rate. A difference method had been choosen which provided applicable results with respect to characteristic quantities of the substance under corresponding initial and boundary conditions. Some pictures show the deviation of temperature and concentration.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 45
    Electronic Resource
    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 2 (1982), S. 331-336 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: The configuration and hardware components of a desk-top computer coupled system for bench-top bioreactors are described. Examples of on-line acquisition of several directly accessible environmental process parameters and computations of directly inaccessible state variables are presented. The system described offers great advantages in experiments for establishing sophisticated control algorithms and for studying the physiological behaviour of microbial populations.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 46
    Electronic Resource
    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 2 (1982), S. 337-342 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Cell-free growth liquor of Acinetobacter calcoaceticus 69-V contains an extracellular lipase. Its activity depends on growth phase and carbon source. During growth on acetate or succinate the activity ist low or zero, respectively. Growth on alkanes causes an increase in the extracellular lipase activity. Activity reaches maximum values during the exponential phase of growth which significantly decrease in the stationary phaseDuring the growth on alkanes some surfactants (Tauroglycocholate, Triton X-405) stimulate the excretion of the enzyme and some other (Tween, Brij, Triton X-100) inhibit the lipase and growth of cells, respectivelyAir-water and alkane-water interfaces inhibit the lipase activity. During starvation of the bacteria grown on alkanes lipase is excreted in the starvation medium.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 47
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: In the laboratory scale fermentation the substitution of peanutmeal by a hydrolysate of Penicillium mycelium in the culture medium for production of L-Lysine with Brevibacterium flavum CB has been testet. The mycelium hydrolysate contains Penicillin and degradation products of Penicillin; therfor the influence of these substances to production of L-Lysine has been investigated.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 48
    Electronic Resource
    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 2 (1982) 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 49
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: The knowledge of surface area of microbial biomasses is necessary in connection to mass-transfer processes for instance extraction process. The method of BRUNAUER, EMMETT and TELLER (BET) based on adsorption processes was adapted to determination of surface area of samples of dry yeast. Comparative investigations and error estimations show the possibility of application and the evidence of this method.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 50
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 51
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Prolidase, a specific exopeptidase, is isolated from Escherichia coli B. The enzyme being present in the raw extract is purified and enriched by fractionated ammonium sulfate precipitation, ion exchange chromatography on DEAE-Sephadex A 50 as well as by gel filtration on Sepharose 4 B. Total yield of prolidase amounts to 19% with a 67fold enrichmentSubstrate specifity of the enzyme mainly corresponds to that of the animal prolidase. It is able to hydrolize the imido linkage at the N-terminal end of prolin in the case of di- and tripeptides. The temperature optimum of prolidase from E. coli B is 37 °C, the pH-optimum from pH 7.6 to 9.0. Storage stability at pH 8.6 and a temperature of 4 °C is optimal. The enzyme is only active in presence of Mn2+-ions. This metal cannot be replaced by Mg2-- or Zn2+-ionsA high enzyme activity and storage stability in presence of Mn2+-ions can be reached by immobilization of the prolidase, by covalent binding on Sepharose 6 B, adsorption on DEAE-Sephadex as well as by combination with glutar dialdehyde on DEAE-Sephadex.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 52
    Electronic Resource
    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 2 (1982), S. 171-177 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: After exhaustion of the N-sources the yeast S.l. excretes citric and isocitric acid with high rates without interferring in the postlogarithmic phase the intracellular production of reserve materials like polysaccharides and especially lipids. The synthesis of citric acids and of reserve materials are therefore autonomically proceeding processes inside of the cellsWith increasing lipid content the ergosterol content increasesThe utilization of the ergosterol rich yeasts as valuable byproduct of the citric acid production is discussed.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 53
    Electronic Resource
    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 2 (1982), S. 186-186 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 54
    Electronic Resource
    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 2 (1982), S. 145-153 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: The removal of the content of nucleic acids of fodder yeast (Candida utilis) by treatment with HCl or heat shock was investigatedAcid concentrations between 5 and 15% (on dried matter basis) were used. A maximal removal of the content of nucleic acids of 88% was realized wheńn was worked with 15% HCl, 90 °C during 30 minutes. But under this conditions were observed high demanges of protein and also of some essential amino acidsGood results for diminishing the content of nucleic acids were reached with the highest concentration of acid and a treatment during 20 minutesThe experiments with heat shock were carried out at 68 °C, different times for heating and different contents of yeastIn this way better results than for treatment with acid according to diminishing the content of nucleic acids and yield of protein and essential amino acids were reachedA removal of over 80% of the content of nucleic acids was achieved in all cases.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 55
    Electronic Resource
    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 2 (1982), S. 155-160 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Lipids were extracted from the cells of Acinetobacter calcoaceticus EB 10 C IMET B 395 grown on gas oil (Bp. 240-360 °C) with benzine/alcohol (80 : 20). The lipid-hydrocarbon-extract obtained by this extraction method was 18.4%. The extract was composed of hydrocarbons, waxes, phospholipids, fatty acids, glycerides, and ubiquinones. The main components among the lipids were waxes. The compositions of phospholipid, fatty acid, wax, and ubiquinone fractions were analysed.
    Additional Material: 7 Tab.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 56
    Electronic Resource
    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 2 (1982), S. 287-296 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: A bacterium isolated from Assam (India) soil was found to accumulate L-lysine in the mineral salt-hydrocarbon medium and identified to be a strain of Micrococcus luteus. The strain is able to grow and accumulate l-lysine in a purely synthetic medium, but supplementation of the synthetic medium with casamino acid or yeast extract or both, improves the yield. The entire fermentation period can be divided into a growth phase and a production phase, which can be prolonged by adjustment of the pH to the neutral range. Among the different hydrocarbon and nitrogen sources tested straight run gas oil (47percnt;) and ammonium sulphate (0.4%), respectively, were found most suitable.Erythromycin at 1 μg/ml level inhibited growth bu¸t stimulated lysine excretion. An inoculum level of 10% (v/v) of the medium was optimal for lysine production. The yield of lysine under optimal conditions was found to be 3.25 g per litre of the medium. Lysine has been isolated in crystalline form from the fermented broth by ion exchange resin chromatography and found to be pure sample of L-isomer.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 57
    Electronic Resource
    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 2 (1982), S. 343-358 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: The first supplement of a review on recent literature is given concerning the immobilization of whole microbial cells and their testing for application in product synthesis. It includes the same topics as the first review, essentially, together with the table of the immobilized microbes and the tested reactions of product synthesis or analytical purpose, respectively, with 177 references.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 58
    Electronic Resource
    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 2 (1982), S. 359-368 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: The biochemical functions of Polyribonucleotide phosphorylase (PNP-ase; EC 2.7.7.8) has been studiedThe present work was aimed at studying the interrelation between PNP-ase biosynthesis and RNA content of E. coli cells under various conditions of bacterial growth, obtaining the biomass of E. coli with high PNP-ase activity as well as to study the possibility of secondary cultivation of E. coli cells for obtaining polyribonucleotides from nucleoside-5′-diphosphatesThe spcific PNP-ase activity increases at secondary cultivation, when the medium contains ribonucleoside-5′-diphosphates. Besides one may observe an extracellular polycondensation of nucleoside-5′-diphosphatesIt may be presumed that the PNP-ase is a multifunctional enzyme whose biological role may be confined to regulating the energetic processes connected with the metabolism of glucose, nucleosidephosphates and orthophosphate in the cells of E. coli.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 59
    Electronic Resource
    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 2 (1982), S. 387-387 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 60
    Electronic Resource
    Electronic Resource
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 2 (1982), S. 377-385 
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: The kinetics of the prehydrolysis of rice hulls where investigated with different concentrations of H2SO4 and temperatures by modified ARRHENIUS-equation in relation to the degradation of pentosans and the formation of reducing sugars. The determination of the activation energy, the frequency-factor and the orden of reaction in relation to the concentration of the acid results for the formation of the reducing sugars in 60.3 kJ/mol, 5.28 ×. 107 and 1.76, for the degradation of the pentosans in 59- and 69.9 kJ/mol, 3.08 × 107 and 6.03 times; 107 as well as 0.76 and 0.85The discontinuous growth of the yeast Candida tropicalis QML 7601, isolated from a biotop in Cuba, on the products of the prehydrolysis of the rice hulls with H2SO4 (0.1- and 0.2 N) and different mixtures of H2SO4 and HNO3 yield values of μmax = 0.3 - 0.6 h-1 in relation to the conditiones.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 61
    Electronic Resource
    Electronic Resource
    New York, N.Y. : Wiley-Blackwell
    Journal of Supramolecular Structure 10 (1979), S. 307-327 
    ISSN: 0091-7419
    Keywords: fibroblasts ; plasma membranes ; contact inhibition ; growth control ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Addition of a suspension of a surface membrane enriched fraction prepared from confluent 3T3 cells to sparse 3T3 cells in culture results in a concentration dependent and saturable decrease in the rate of DNA synthesis. The inhibition of cell growth by membranes resembles the inhibition of cell growth observed at confluent cell densities by a number of criteria: (1) In both cases the cells are arrested in the G1 protion of the cell cycle; (2) the inhibition by membranes or by high local cell density can to a large extent be compensated for by raising the serum concentration or by addition of fibroblast growth factor plus dexamethasone. Membranes prepared from sparse cultures inhibit less well than membranes from confluent cultures in a manner which suggests that binding of membranes to cells is not by itself sufficient to cause inhibition of cell growth. The inhibitory activity has a subcellular distribution similar to phosphodiesterase (a plasma membrane marker) and appears to reside in one or more intrinsic membrane components. Maximally, membranes can arrest about 40% of the cell population in each cell cycle. Plasma membranes obtained from sparse 3T3 cells are less inhibitory than membranes obtained from confluent cells. This suggests either that the inhibitory component(s) in the plasma membrane responsible for growth inhibition may be in part induced by high cell density, or that this component(s) may be lost from these membranes during purification.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 62
    Electronic Resource
    Electronic Resource
    New York, N.Y. : Wiley-Blackwell
    Journal of Supramolecular Structure 11 (1979), S. 327-338 
    ISSN: 0091-7419
    Keywords: AcChR-enriched membranes ; pyrenesulfonyl azide ; fluorescent probes ; photolabeling ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Acetylcholine receptor (AcChR) enriched membrane fragments from Torpedo californica electroplax were labeled by in situ photogenerated nitrenes from a hydrophobic fluorescent probe, pyrene-1-sulfonyl azide. Preferential photolabeling of membrane proteins, mainly AcChR, has been achieved and there is a pronounced exposure of the 48,000 and 55,000 molecular weight subunits of AcChR to the lipid environment of the membrane core.Covalent attachment of the photogenerated fluorescence probe does not perturb the α-neurotoxins' binding properties of membrane-bound AcChR or the desensitization kinetics induced by prolonged exposures to cholinergic agonists. Non-covalent photoproducts can be conveniently removed from labeled membrane preparations by exchange into lipid vesicles prepared from electroplax membrane lipids. Fluorescence features of model pyrene sulfonyl amide derivatives, such as fine vibrational structure of emission spectra or fluorescence lifetimes, are highly sensitive to the solvent milieu. The covalently bound probe shows similar fluorescence properties in situ. PySA photoproducts have great potential to spectroscopically monitor neurotransmitter induced events on selected AcChR subunits exposed to the hydrophobic environment of membranes.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 63
    Electronic Resource
    Electronic Resource
    New York, N.Y. : Wiley-Blackwell
    Journal of Supramolecular Structure 12 (1979), S. 1-14 
    ISSN: 0091-7419
    Keywords: myosin ; Dictyostelium ; RNA ; motility ; nonmuscle cells ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Myosin purified from Dictyostelium amoebae has approximately 10% by weight of RNA associated with it, unless specific steps (DEAE cellulose chromatography or R Nase digestion) are taken to remove it. This RNA has significant effects on the structural states formed by the myosin at low ionic strength in the presence of Mg2+.Rapid precipitation of Rna-free myosin by dilution generates bipolar thick filaments (540 nm long, 33 nm thick), often with a bare zone and a 15-nm transverse repeat. Rapid precipitation of myosin with copurified RNA yields linear aggregates of bipolar filaments, showing some lateral association.Slow precipitation of RNA-free myosin by dialysis yields very long filaments or ribbons (〉5 μm, 30-60 nm wide) in which the myosin may be packed diagonally across the filament, similar to the “side-polar” aggregates formed by other nonmuscle myosins and by smooth muscle myosin (Craig R, Megerman J: J Cell Biol 75:990, 1977; Hinssen H, D'Haese J, Small JV, Sobieszek A: J Ultrastruct Res 64:282, 1978). Slow precipitation of myosin with copurified RNA generates linear filaments with repeat intervals of 290 and 650 nm.Other polyanions were tested for their effects on myosin aggregation. Total RNA and ribosomal RNA from Dictyostelium, when added to RNA-free myosin, also induced the extensive linear aggregation seen with the copurified RNA/myosin complex, although higher concentrations of RNA were required to obtain quantitatively the same effect. DNA and heparin were also effective inducers of linear aggregation, whereas homopolymers of nucleotides and of acidic or basic amino acids were poorly effective.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 64
    Electronic Resource
    Electronic Resource
    New York, N.Y. : Wiley-Blackwell
    Journal of Supramolecular Structure 12 (1979), S. 293-298 
    ISSN: 0091-7419
    Keywords: SEM ; chemical carcinogenesis in vitro ; epithelial liver cell cultures ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: A scanning electron microscopy study was carried out on differentiated liver cells transformed in vitro by three chemical carcinogens into cells that give rise to carcinomas. The results indicate that the transformed cells grow as a rule in tightly adherent monolayers but differ in topography. There is a tendency toward heterogeneity in cell shape compared to the normal and on the whole toward a larger number of surface microvilli in the malignant cell population. However, both in sparse and confluent cultures the topographic differences are often not striking enough to unequivocally distinguish single neoplastic cells from the normal.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 65
    Electronic Resource
    Electronic Resource
    New York, N.Y. : Wiley-Blackwell
    Journal of Supramolecular Structure 12 (1979), S. 321-334 
    ISSN: 0091-7419
    Keywords: denervated sarcolemma ; nonsynaptic acetylcholine receptors ; 125I-α-bungarotoxin ; ferritin-α-bungarotoxin ; electron microscopy ; freeze-fracture ; freeze-etching ; autoradiography ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: The nonsynaptic sarcolemma of denervated skeletal muscle of rat shows an abundance of ∼15 nm intramembranous particles on the P face. These particles are either singly distributed or are in clusters, and they are essentially lacking from the comparable freeze-fractures of the innervated sarcolemma. Autoradiographic studies using 125I-α-bungarotoxin (BGT) on 1 μ-thick sections, and freeze-etch studies using ferritin-α-BGT conjugates on membrane fractions, show that the distribution of the label corresponds to the distribution of the 15-nm particles in the nonsynaptic sarcolemma. On the basis of these results and existing physiologic and biochemical data, it is suggested that the 15-nm intramembranous particles are components of the α-BGT binding sites, ie, acetylcholine (Ach) receptors, in the nonsynaptic sarcolemma of denervated muscle and that the two types of distributions represent two spatial manifestations of Ach receptor molecules. The significance of these findings in relation to synapse formation in denervated muscle is discussed.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 66
    Electronic Resource
    Electronic Resource
    New York, N.Y. : Wiley-Blackwell
    Journal of Supramolecular Structure 12 (1979) 
    ISSN: 0091-7419
    Keywords: Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 67
    Electronic Resource
    Electronic Resource
    New York, N.Y. : Wiley-Blackwell
    Journal of Supramolecular Structure 12 (1979), S. 425-433 
    ISSN: 0091-7419
    Keywords: rat liver ribosomal proteins ; amino-terminus ; yeast ribosomes ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: The sequence of the amino-terminal region of eleven rat liver ribosomal proteins-S4, S6, S8, L7a, L18, L27, L30, L37a, and L39 - was determined. The analysis confirmed the homogeneity of the proteins and suggests that they are unique, since no extensive common sequences were found. The N-terminal regions of the rat liver proteins were compared with amino acid sequences in Saccharomyces cerevisiae and in Escherichia coli ribosomal proteins. It seems likely that the proteins L37 from rat liver and Y55 from yeast ribosomes are homologous. It is possible that rat liver L7a or L37a or both are related to S cerevisiae Y44, although the similar sequences are at the amino-terminus of the rat liver proteins and in an internal region of Y44. A number of similarities in the sequences of rat liver and E coli ribosomal proteins have been found; however, it is not yet possible to say whether they connote a common ancestry.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 68
    ISSN: 0091-7419
    Keywords: nuclear matrix ; estrogen ; RNA ; uridine ; Xenopus laevis ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: At various times following estorgen administration, the nuclear matrix was isolated from the liver of male Xenopus laevis by sucrose gradient centrifugation of nuclei treated with a high-salt buffer and DNase I in the presence of a proteolytic inhibitor (PMSC - phenylmethyl sulfonyl chloride). Electron micrographs of the nuclear matrix demonstrate a sponge-like network attached to a well-defined inner envelope with a ribosome-free outer envelope. Chemical analyses show that the HSB-DNase-treated nuclei consist of 16% DNA, 2% RNA, and 82% protein, a composition that is consistent with that of nuclear matrices isolated from other species. The specific activity of the matrix-associated RNA following estrogen treatment appears to be maximally enhanced after 5 h and decreases until approximately 12 h, when the activity begins to increase again.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 69
    Electronic Resource
    Electronic Resource
    New York, N.Y. : Wiley-Blackwell
    Journal of Supramolecular Structure 12 (1979) 
    ISSN: 0091-7419
    Keywords: Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 70
    Electronic Resource
    Electronic Resource
    New York, N.Y. : Wiley-Blackwell
    Journal of Supramolecular Structure 12 (1979), S. 79-120 
    ISSN: 0091-7419
    Keywords: Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 71
    ISSN: 0091-7419
    Keywords: vertebrate photoreceptor ; cyclic GMP ; cyclic nucleotide regulation ; phosphodiesterase ; light activated GTPase ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: We report experiments which involve a light sensitive GTPase in the light dependent activation of retinal rod 3′5′-cyclic guanosine monophosphate (cGMP) phosphodiesterase (PDE). The data suggest that the light activated GTPase is intermediate between rhodopsin and PDE in the light-dependent activation sequence. We list the many striking similarities between hormone sensitive adenylate cyclase and light activated PDE in order to emphasize that the findings presented herein may have predictive value for ongoing studies of the hormone sensitive adenylate cyclase specifically regarding the role of the hormone activated GTPase in the activation sequence.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 72
    Electronic Resource
    Electronic Resource
    New York, N.Y. : Wiley-Blackwell
    Journal of Supramolecular Structure 10 (1979), S. 359-364 
    ISSN: 0091-7419
    Keywords: ribosomes ; crystallization ; hypothermia ; chick embryos ; degeneration ; cell suffering ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: The relationship between ribosome crystallization and cell degeneration has been studied in chick embryos at various temperatures, and new methods of inducing ribosome microcrystals are described. A model is discussed that reinterprets the role of low temperatures in these phenomena and provides a unitary explanation of the various cases in which the occurrence of ribosome crystallization in chick embryos has been reported.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 73
    Electronic Resource
    Electronic Resource
    New York, N.Y. : Wiley-Blackwell
    Journal of Supramolecular Structure 10 (1979), S. 397-404 
    ISSN: 0091-7419
    Keywords: electron microscopy ; hybrid ribosome ; ribosome structure ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Small 40S Artemia salina and large 50S Escherichia coli ribosomal subunits can be assembled into 73S hybrid monosomes active in model assays for protein synthesis. The reciprocal combination-small 30S E coli and large 60S A salina-fails to form hybrids. The 73S hybrid particles strongly resemble homologous 70S E coli and 80S A salina monosomes. The morphologic differences between the corresponding eukaryotic and prokaryotic ribosomal particles, established by electron microscopy, do not significantly affect the assembly and mutual orientation of 40S A salina and 50S E coli subunits in the heterologous monosome. The fact that the structure of the interface, the supposed site of protein synthesis, is preserved in the active hybrid implies that retention or loss of biologic activity of hybrid ribosomes is determined by the extent of conformational changes in the interface.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 74
    Electronic Resource
    Electronic Resource
    New York, N.Y. : Wiley-Blackwell
    Journal of Supramolecular Structure 10 (1979), S. 433-441 
    ISSN: 0091-7419
    Keywords: macrophage (alveolar) ; plasma membrane ; Ca2+-ATPase reaction ; membrane phosphorylation ; Ca2+ buffering ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: ATPase activity and phosphorylation by [γ-32P] ATP of isolated plasma membrane of alveolar macorphages are stimulated in a parallel fashion by physiologic concentrations of Ca2+, with half-maximal activating effect of this ion at (3-7) × 10-7 M. For various membrane preparations, a direct proportionality exists between Ca2+-dependent ATPase activity and amount of 32P incorporated. Labeling of membrane attains the steady-state level by 10 sec at 0°C, and is rapidly reversed by adenosine diphosphate (ADP). K+ decreases the amount of membrane-bound 32P, mainly by enhancing the rate of dephosphorylation of the 32P-intermediate. Hydroxylamine causes a release of about 90% of 32P bound to the membrane, thus indicating that the 32P-intermediate contains an acyl-phosphate bond. When the labeled plasma membrane is solubilized and electrophoresed on acrylamide gels in the presence of sodium dodecyl sulphate, the radioactivity appears to be largely associated with a single protein fraction of 132,500 ± 2,000 apparent molecular weight. These features of the macrophage Ca2+-ATPase suggest that the enzyme activity might be part of a surface-localized Ca2+-extrusion system, participating in the regulation of Ca2+-dependent activities of the macrophage.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 75
    ISSN: 0091-7419
    Keywords: cell adhesion ; adhesion proteins ; fibronectin ; chondronectin ; collagen substrates ; gangliosides ; cell surface ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Fibronectin mediates the adhesion of fibroblasts to collagen substrates, binding first to the collagen and then to the cells. We report here that the interaction of the cells with the fibronectin-collagen complex is blocked by specific gangliosides, GD1 a and GT1, and that the sugar moieties of these gangliosides contain the inhibitory activity. The gangliosides act by binding to fibronectin, suggesting that they may be the cell surface receptor for fibronectin. Evidence is presented that other adhesion proteins or mechanisms of attachment exist for chondrocytes, epidermal cells, and transformed tumorigenic cells, since adhesion of these cells is not stimulated by fibronectin. Chondrocytes adhere via a serum factor that is more temperature-sensitive and less basic than fibronectin. Unlike that of fibroblasts chondrocyte adhesion is stimulated by low levels of gangliosides. Epidermal cells adhere preferentially to type IV (basement membrane) collagen but at a much slower rate than fibroblasts or chondrocytes. This suggests that these epidermal cells synthesize their own specific adhesion factor. Metastatic cells cultured from the T241 fibrosarcoma adhere rapidly to type IV collagen in the absence of fibronectin and do not synthesize significant amounts of collagen or fibronectin. Their growth, in contrast to that of normal fibroblasts, is unaffected by a specific inhibitor of collagen synthesis. These data indicate the importance of specific collagens and adhesion proteins in the adhesion of certain cells and suggest that a reduction in the synthesis of collagen and of fibronectin is related to some of the abnormalities observed in transformed cells.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 76
    Electronic Resource
    Electronic Resource
    New York, N.Y. : Wiley-Blackwell
    Journal of Supramolecular Structure 11 (1979), S. 117-122 
    ISSN: 0091-7419
    Keywords: dynein ATPase ; latency ; high-affinity binding site ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: The enhancing effect of low concentrations (eg, 8 μM) of bis(4-fluoro-3-nitrophenyl)sulfone (FNS) on 30S dynein ATPase activity is increased when 1 mM dithiothreitol (DTT) is present. The effect of FNS + DTT is optimal at pH 7.5. Activation of the latent ATPase activity of 30S dynein by FNS + DTT is partially prevented by 1-3 μM ATP. Adenylylimidodiphosphate (AMP-PNP) is less effective than ATP, while β,γ-methylene-adenosine triphosphate (AMP-PCP), though a much stronger inhibitor of ATPase activity than AMP-PNP, does not protect against enhancement. These results demonstrate the presence of a high-affinity ATP-binding site on 30S dynein.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 77
    Electronic Resource
    Electronic Resource
    New York, N.Y. : Wiley-Blackwell
    Journal of Supramolecular Structure 11 (1979) 
    ISSN: 0091-7419
    Keywords: Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 78
    Electronic Resource
    Electronic Resource
    New York, N.Y. : Wiley-Blackwell
    Journal of Supramolecular Structure 11 (1979), S. 467-476 
    ISSN: 0091-7419
    Keywords: metastatic potential ; growth rates ; chromosome number and range ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: We investigated whether the metastatic potential of various tumor cell lines was related to chromosome counts or to rate of growth in vitro or in vivo. Clones of known metastatic potential derived from a C3H- fibrosarcoma induced by UV radiation (UV-2237) and from C57BL/6 B16 melanoma were tested for these characteristics. No correlation was found between the growth rate of these clones in monolayer culture or at a subcutaneous site and their ability to produce metastases. The cells from clones of UV-2237 were mainly in the diploid range with only one exception, and the B16 clones were all hyperploid. Thus, there was also no correlation between malignant behavior of the clones and gross changes in chromosome number.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 79
    Electronic Resource
    Electronic Resource
    New York, N.Y. : Wiley-Blackwell
    Journal of Supramolecular Structure 11 (1979), S. 493-502 
    ISSN: 0091-7419
    Keywords: cell surface ; plasma membrane ; glycoproteins ; affinity chromatography ; lectins ; Novikoff hepatocellular carcinoma ; neuraminidase ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Novikoff hepatocellular carcinoma cells were radioiodinated by a cell surface-specific method using lactoperoxid ase/125I. The iodinated proteins were solubilized in 0.5% Nonidet P-40 and subjected to affinity chromatography on Sepharose-conjugated lectins (Ricinus communis agglutinins I or II, soybean agglutinin, concanavalin A, or wheat germ agglutinin) and analyzed by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate. Almost all the iodinated proteins bound to one or more of the Sepharose-conjugated lectins, presumptive evidence that these peptides are glycosylated. Lectin affinity chromatography resolved defined subsets of iodinated glycoproteins and suggested that certain glycoproteins could be fractionated on the basis of heterogeneity of their heterosaccharide moieties. Incubation of the iodinated cells with neuraminidase resulted in increased binding of iodinated proteins to Sepharose-conjugated Ricinus communis agglutinins I and II and soybean agglutinin and decreased binding to Sepharose-conjugated wheat germ agglutinin. Binding of iodinated proteins to concanavalin A was unaffected by neuraminidase treatment of the cells. These studies demonstrate the utility of lectins for the multicomponent analysis of plasma membrane proteins.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 80
    Electronic Resource
    Electronic Resource
    New York, N.Y. : Wiley-Blackwell
    Journal of Supramolecular Structure 11 (1979), S. 539-546 
    ISSN: 0091-7419
    Keywords: SV40 transformation ; tumorigenicity ; anchorage independence ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: A syndrome of in vitro properties correlates with the tumorigenicity of SV40-transformed rodent cells. These properties are plasminogen activator production, loss of large actin cables, and anchorage-independent growth. An established rat fibroblast line, its SV40 transformant, several T-antigen negative revertants, and a spontaneous retransformant isolated form one of the revertants were analyzed in vivo for their tumorigenicity and in vitro for the syndrome. The two transformed lines were highly tumorigenic, and had clearly abnormal in vitro properties. The parental rat line was weakly tumorigenic in nude mice and demonstrated a slightly transformed response in the in vitro assays. The revertants were completely nontumorigenic. Expression of the in vitro syndrome was not uniform for all revertants; however, most cell lines maintained the correlation of the syndrome and tumorigenicity.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 81
    Electronic Resource
    Electronic Resource
    New York, N.Y. : Wiley-Blackwell
    Journal of Supramolecular Structure 11 (1979), S. 563-577 
    ISSN: 0091-7419
    Keywords: plasma membrane ; lectin receptors ; affinity chromatography ; membrane proteins ; hybridoma ; monoclonal antibody ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Concanavalin A-binding (Con A)-binding cell surface glycoproteins were isolated, via Con A-affinity chromatography, from Triton X-100-solubilized Chinese hamster ovary (CHO) cell plasma membranes. The Con A binding glycoproteins isolated in this manner displayed a significantly different profile on sodium dodecyl sulfate-polyacrylamide gels than did the Tritonsoluble surface components, which were not retarded by the Con A-Sepharose column. [125I]-Con A overlays of the pooled column fractions displayed on sodium dodecyl sulfate-polyacrylamide gel electro-phoresis (SDS-PAGE) demonstrated that there were virtually no Con A receptors associated with the unretarded peak released by the Con A-Sepharose column, whereas the material which was bound and specifically eluted from the Con A-Sepharose column with the sugar hapten α-methyl-D-mannopyranoside contained at least 15 prominent bands which bound [125I]-Con A.In order to produce monoclonal antibodies against various cell surface Con A receptors, Balb/c mice were immunized with the pooled Con A receptor fraction. Following immunization spleens were excised from the animals and single spleen cell suspensions were fused with mouse myeloma P3/X63-Ag8 cells. Numerous hybridoma clones were subsequently picked on the basis of their ability to secrete antibody which could bind to both live and glutaraldehyde-fixed CHO cells as well as to the Triton-soluble fraction isolated from the CHO plasma membrane fraction. Antibody from two of these clones was able to precipitate a single [125I]-labeled CHO surface component of ∼265,000 daltons.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 82
    Electronic Resource
    Electronic Resource
    New York, N.Y. : Wiley-Blackwell
    Journal of Supramolecular Structure 11 (1979), S. 9-24 
    ISSN: 0091-7419
    Keywords: nascent chains ; co-translational modification ; glycosylation ; polypeptide folding ; covalent assembly ; heavy and light chains ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: We have investigated the in vivo co-translational covalent modification of nascent immunoglobulin heavy and light chains. Nascent polypeptides were separated from completed polypeptides by ion-exchange chromatography of solubilized ribosomes on QAE-Sephadex. First, we have demonstrated that MPC 11 nascent heavy chains are quantitatively glycosylated very soon after the asparaginyl acceptor site passes through the membrane into the cisterna of the rough endoplasmic reticulum. Nonglycosylated completed heavy chains of various classes cannot be glycosylated after release from the ribosome, due either to rapid intramolecular folding and/or intermolecular assembly, which cause the acceptor site to become unavailable for the glycosylation enzyme. Second, we have shown that the formation of the correct intrachain disulfide loop within the first light chain domain occurs rapidly and quantitatively as soon as the appropriate cysteine residues of the nascent light chain pass through the membrane into the cisterna of the endoplasmic reticulum. The intrachain disulfide loop in the second or constant region domain of the light chain is not formed on nascent chains, because one of the cysteine residues involved in this disulfide bond does not pass through the endoplasmic reticulum membrane prior to chain completion and release from the ribosome. Third, we have demonstrated that some of the initial covalent assembly (formation of interchain disulfide bonds) occurs on nascent heavy chains prior to their release from the ribosome. The results are consistent with the pathway of covalent assembly of the cell line, in that completed light chains are assembled onto nascent heavy chains in MPC 11 cells (IgG2b), where a heavy-light half molecule is the major initial covalent intermediate; and completed heavy chains are assembled onto nascent heavy chains in MOPC 21 cells (IgG1), where a heavy chain dimer is the major initial disulfide linked intermediate.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 83
    Electronic Resource
    Electronic Resource
    New York, N.Y. : Wiley-Blackwell
    Journal of Supramolecular Structure 11 (1979), S. 33-49 
    ISSN: 0091-7419
    Keywords: cell enucleation ; cell reconstruction ; nuclear control of tumorigenicity ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: The techniques of somatic cell hybridization have provided a valuable means of studying mechanisms of regulation of mammalian cell differentiation and transformation. Most previous studies have indicated that fusions between tumorigenic and nontumorigenic cells result in hybrid cells that are usually tumorigenic. In recent years it has been demonstrated that the phenotypic expression of tumorigenicity is at least partially due to the extensive chromosome loss that occurs in most interspecific and some intraspecific hybrid cells. In the present study we have utilized enucleation techniques that permit cells to be divided into nuclear (karyoplast) and cytoplasmic (cytoplast) cell fragments. Even though these nuclear and cytoplasmic fragments are metabolically stable for short periods of time, in our hands they ultimately degenerate. Viable cells can be reconstructed by PEG-induced fusion of karyoplasts to cytoplasts. Since reconstructed cells apparently do not segregate chromosomes, they may provide a clearer understanding of the interactions between the nucleus and the cytoplasm in the control of the expression of tumorigenicity. We have reconstructed cells using karyoplasts from the tumorigenic Y-1 cell line and cytoplasts from a nontumorigenic cell line, A-MT-BU-A1. In addition we have reconstructed cells containing Y-1 cytoplasts and A-MT-BU-A1 karyoplasts. The reconstructed cells porduced were assayed for tumorigenicity by their ability to grow in soft agar and in nude mice. The results of these experiments indicate that the reconstructed cells containing a tumorigenic nucleus and a nontumorigenic cytoplasm ultimately are tumorigenic and conversely the reconstructed cells containing a nontumorigenic nucleus and a tumorigenic cytoplasm are nontumorigenic. These experiments support the concept that with these cell lines the nucleus (karyoplast) is sufficient to control the phenotypic expression of tumorigenicity.
    Additional Material: 18 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 84
    Electronic Resource
    Electronic Resource
    New York, N.Y. : Wiley-Blackwell
    Journal of Supramolecular Structure 11 (1979) 
    ISSN: 0091-7419
    Keywords: Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 85
    Electronic Resource
    Electronic Resource
    New York, N.Y. : Wiley-Blackwell
    Journal of Supramolecular Structure 11 (1979), S. 123-138 
    ISSN: 0091-7419
    Keywords: pea stem membranes ; L-cell membranes ; polyisoprenyl oligosaccharides ; glycoprotein synthesis ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Membrane preparations from growing regions of pea stems and activelydividing mouse L-cells form lipid-linked saccharides from GDP-mannose and UDP-N-acetylglucosamine. These lipids have properties which are consistent with those of mono-and di-phosphoryl polyisoprenyl derivatives.In experiments using plant membranes, the monophosphoryl derivative labeled with GDP-(14C) mannose contains mannose only, while the diphosphoryl derivative labeled with the same nucleotide sugar is heterogeneous, containing oligosaccharides corresponding to mannosaccharides of 5, 7, and 9-12 residues. Only the diphosphoryl polyisoprenyl derivatives are labeled with UDP-(14C)glucosamine and these contain predominantly chitobiose and N-acetylglucosamine itself. Unlabeled GDP-mannose added after UDP-N-acetyl (14C)glucosamine results in the formation of higher lipid-linked oligosaccharides which are apparently the same as those which are labeled with GDP-(14C)mannose alone. Incubation of the membranes with GDP-(14C)mannose in the presence of Mn2+, unlabeled UDP-glucose or unlabeled UDP-N-acetylglucosamine results in marked changes in the accumulation of both the polyisoprenyl monophosphoryl mannose and polyisoprenyl diphosphoryl oligosaccharides.Animal cell membranes synthesise lipid-linked oligosaccharides when incubated with UDP-N-acetylglucosamine and GDP-mannose. These oligosaccharides are similar in size to those synthesised by the plant membranes but their formation is more efficient. The potential roles of these compounds in glycoprotein biosynthesis in both plant and animal tissues is discussed.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 86
    ISSN: 0091-7419
    Keywords: cellular adhesion ; platelets ; fibronectin ; hemostasis ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Platelets are cells which develop adhesive properties following stimulation. Since fibronectin (fn) mediates adhesive properties of several cells, we sought evidence for platelet associated fn. Lysates of suspensions of washed human platelets containing ≤50 ng soluble fn/109 cells contained 2.85 μg fn antigen per 109 cells. The platelet fn antigen competition curve showed a similar slope to the curve for purified plasma fn suggesting antigenic identity. Immunofluorescent staining for fn was minimal in intact cells suggesting that the majority of fn antigen is intracellular. In permeable platelets, fluorescent staining for fn was seen in a punctate distribution suggesting a granule localization. Stimulation of platelet secretion by thrombin released platelet fn antigen. Suramin, a drug which inhibits platelet secretion, inhibited fn release. The apparent secretion of platelet fn, taken with the immunofluorescent data, support the localization of a portion of platelet fn antigen in a storage granule.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 87
    Electronic Resource
    Electronic Resource
    New York, N.Y. : Wiley-Blackwell
    Journal of Supramolecular Structure 11 (1979), S. 175-187 
    ISSN: 0091-7419
    Keywords: growth control ; 3T3 cells ; Schwann cells ; neurites ; plasma membranes ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Control of cell growth by cell to cell contact is reviewed with particular emphasis on two systems - contact inhibition of growth observed with Swiss 3T3 cells and the mitogenic stimulation of Schwann cells by dorsal root ganglia neurites. In both cases the biological effect can be reproduced by the addition of surface membranes to the corresponding cells. In the case of contact inhibition of 3T3 cells, biological activity appears to correlate with membrane binding to the cells. An octylglucoside extract of 3T3 plasma membranes retains the biological activity (growth inhibition) of the original membranes.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 88
    Electronic Resource
    Electronic Resource
    New York, N.Y. : Wiley-Blackwell
    Journal of Supramolecular Structure 11 (1979), S. 207-216 
    ISSN: 0091-7419
    Keywords: renal epithelium ; primary cultures ; prostaglandins ; mammalian cell growth ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Madin Darby canine kidney cells can grow in synthetic medium supplemented with 5 factors - insulin, transferrin, prostaglandin E1, hydrocortisone and triiodothyronine - as a serum substitute. These 5 factors permit growth for one month in the absence of serum, and a growth rate equivalent to that observed in serum-supplemented medium. Dibutyryl cAMP substitutes for prostaglandin E1 in the medium, suggesting that increased growth of Maden Darby canine kidney cells results from increased intracellular cAMP. Potential applications of the serum-free medium are discussed. The medium permits the selective growth of primary epithelial cell cultures in the absence of fibroblast over-growth, and a defined analysis of the mechanisms by which hormones regulate hemicyst formation.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 89
    Electronic Resource
    Electronic Resource
    New York, N.Y. : Wiley-Blackwell
    Journal of Supramolecular Structure 11 (1979), S. 217-225 
    ISSN: 0091-7419
    Keywords: fibrosarcoma culture media ; gel permeation chromatography ; fibronectin-radioimmunoassay ; fibronectin-releasing peptides ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: A sensitive radioimmunoassay, specific for human fibronectin, was used to measure the ability of certain biologically active polypeptides to release fibronectin from cultured human lung fibroblasts into their culture media. Concentrated, serum-free culture supernatant from a human fibrosarcoma cell line was fractionated by gel filtration chromatography in the presence of acetic acid. Various polypeptides with molecular weights between 46,000 and 6,000 were tested for their ability to release fibronectin from cells. The column fraction, containing polypeptides with an apparent molecular weight of 10,000, exhibited the ability to rapidly release fibronectin from target cells. The activity could be inhibited by phenylmethyl sulphonylfluoride. Several other hormonal factors, tested in parallel with the column fractions, failed to show this effect. The 10,000 dalton molecular weight polypeptides may represent a family of cellular gene products responsible for maintenance of low levels of surface associated fibronectin in fibrosarcoma cells and thus be related to their infiltrating properties by preventing the formation of the extracellular matrix.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 90
    Electronic Resource
    Electronic Resource
    New York, N.Y. : Wiley-Blackwell
    Journal of Supramolecular Structure 11 (1979), S. 227-235 
    ISSN: 0091-7419
    Keywords: fibronectin ; factor XIII ; transglutaminase ; collagen ; polyamine ; ∊(γ-glutamyl)-lysin ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Soluble fibronectin is found in body fluids and media of cultured adherent cells. Insoluble fibronectin is found in tissue stroma and in extracellular matrices of cultured cells. Fibronectin is a substrate for factor XIIIa (plasma transglutaminase) and can be cross-linked to collagen and to the α chain of fibrin. We have used sodium dodecyl sulfate-polyacrylamide gel electrophoresis to investigate the possibility that factor XIIIa -mediated cross-linking is influenced by polyamines. Spermidine inhibited cross-linking between fibronectin and type I collagen, isolated α1 (I) collagen chains, or iodinated cyanogen bromide fragment 7 of α1 (I) chains (125I-α1 (I)-CB7). Half-maximal inhibition of crosslinking between 125I-α1 (I)-CB7 and fibronectin was observed when 0.1 mM spermine or spermidine was present. Spermidine, 0.7 mM, partially inhibited cross-linking between fibronectin and the α chain of fibrin but failed to inhibit cross-linking between the fibrin monomers of a fibrin clot. Spermidine also failed to inhibit cross-linking between fibronectin molecules when aggregation of fibronectin was induced with dithiothreitol. In contrast, 0.7 mM monodansylcadaverine inhibited fibronectin-collagen, fibronectin-fibrin, fibronectin-fibronectin, and fibrin-fibrin cross-linking. Spermidine or spermine, 0.7 mM, enhanced the cross-linking between molecules of partially amidinated fibronectin, suggesting that N1,8-(di-γ-glutamyl)-polyamine cross-linkages were formed. Spermidine and spermine failed to enhance cross-linking between monomers of amidinated fibrin. These results indicate that physiologic concentrations of polyamines specifically disturb transglutaminase-catalyzed cross-linking between fibronectin and collagen.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 91
    Electronic Resource
    Electronic Resource
    New York, N.Y. : Wiley-Blackwell
    Journal of Supramolecular Structure 11 (1979), S. 237-250 
    ISSN: 0091-7419
    Keywords: coated vesicles ; coat dissembly ; coat reassembly ; coat dissociation ; clathrin ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Disruption of the coat of coated vesicles is accompanied by the release of clathrin and other proteins in soluble form. The ability of solubilized coated vesicle proteins to reassemble into empty coats is influenced by Mg2+, Tris ion concentration, pH, and ionic strength. The proteins solubilized by 2 M urea spontaneously reassemble into empty coats following dialysis into isolation buffer (0.1 M MES-1 mM EGTA-1 mM MgCl2-0.02% NaN3, pH 6.8). Such reassembled coats have sedimentation properties similar to untreated coated vesicles. Clathrin is the predominant protein of reassembled coats; most of the other proteins present in native coated vesicles are absent. We have found that Mg2+ is important in the coat assembly reaction. At pH 8 in 0.01 M or 0.1 M Tris, coats dissociate; however, 10 mM MgCl2 prevents dissociation. If the coats are first dissociated at pH 8 and then the MgCl2 raised to 10 mM, reassembly occurs. These results suggest that Mg2+ stabilizes the coat lattice and promotes reassembly. This hypothesis is supported by our observations that increasing Mg2+ (10 μM-10 mM) increases reassembly whereas chelation of Mg2+ by (EGTA) inhibits reassembly. Coats reassembled in low-Tris (0.01 M, pH 8) supernatants containing 10 mM MgCl2 do not sediment, but upon dialysis into isolation buffer (pH 6.8), these coats become sedimentable. Nonsedimentable coats are noted also either when partially purified clathrin (peak I from Sepharose CL4B columns) is dialyzed into low-ionic-strength buffer or when peaks I and II are dialyzed into isolation buffer. Such nonsedimentable coats may represent intermediates in the assembly reaction which have normal morphology but lack some of the physical properties of native coats. We present a model suggesting that tightly intertwined antiparallel clathrin dimers form the edges of the coat lattice.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 92
    Electronic Resource
    Electronic Resource
    New York, N.Y. : Wiley-Blackwell
    Journal of Supramolecular Structure 11 (1979), S. 259-267 
    ISSN: 0091-7419
    Keywords: cell surface receptors ; proteolysis of receptors ; positive or negative regulation ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Addition of highly purified thrombin t o cultures of several kinds of nondividing fibroblasts brings about cell division. This stimulation occurs in serum-free medium, permitting studies on its mechanism under chemically defined conditions. Previous studies have shown that action of thrombin a t the cell surface is sufficient to cause cell division and that the proteolytic activity of thrombin is required for its mitogenic effect. These results prompted experiments which showed that there is a cell surface receptor for thrombin and that thrombin must hind to its receptor and cleave it to stimulate cell division. Some of the thrombin that hinds to its receptors becomes attached to them by a linkage that appears to be covalent. However, it is presently unknown whether this direct thrombin receptor complex plays a role in the stimulation.These results raise a number of question that should be explored in future studies. They also provide a foundation on which to build hypotheses about tentative molecular mechanisms that might be involved in the stimulation. Knowledge that thrombin must cleave its receptor to bring about cell division suggests two alternative mechanisms for stimulation by proteolysis. In one the receptor is a negative effector which prevents cell division when it is intact, but not after it has been cleaved. Alternatively, a fragment of the receptor could be a positive effector. In this mechanism, proteolysis by thrombin would produce a specific receptor fragment which brings about cell proliferation. If every protease which cleaves the receptor also stimulates cell division, the receptor is probably a negative effector. In contrast, if certain proteases cleave the receptor but do not stimulate the cells, a fragment of the receptor is likely a positive effector. With negative regulation by the receptor, the controlling events would occur before proteolysis of it, and it might be possible to find putative regulatory molecules by identification of nearest neighbors of the receptor. This should be possible by using bifunctional crosslinking reagents. If a fragment of the thrombin receptor turns out to be a positive effector, it should be possible to identify and study fragments by analyzing the metabolic fate of the receptor. Techniques are now available for this kind of analysis and it should also be possible to determine whether receptor fragments remain in the membrane or whether they are translocated to specific sites within the cell. A critical question to be asked is which of these events and interactions involving the thrombin receptor are necessary for stimulation of cell division. It now appears that the best way to answer this question is to examine these events in a large number of cloned cell populations that are responsive or unresponsive to the mitogenic action of thrombin. If a thrombin-mediated event occurs in all responsive clones but is altered or absent in sonie unresponsive clones, it is probably necessary for stimulation of cell division.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 93
    Electronic Resource
    Electronic Resource
    New York, N.Y. : Wiley-Blackwell
    Journal of Supramolecular Structure 11 (1979), S. 295-309 
    ISSN: 0091-7419
    Keywords: threshold effects ; liposomes ; aggregation ; ricin ; concanavalin A ; synthetic glycolipids ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Cholesterol analogs containing sugar residues linked by spacer groups to the cholesterol O can be incorporated into egg yolk lecithin small unilamellar liposomes. The synthetic glycolipid analogs distribute evenly on both sides of the bilayer. These liposomes are aggregated by the appropriate lectin. For example, when the sugar residue is a β-galactoside the liposomes are aggregated by ricin and when it is an α-mannoside they are aggregated by Con A. The lectin-mediated aggregation of these liposomes is reversed by the addition of the appropriate sugar. The rates but not the extents of aggregation of these liposomes are highly sensitive to the amount of glycolipid incorporated. Below approximately 5% glycolipid incorporation the rate of the lectin-mediated aggregation of these liposomes is exceedingly slow, whereas above this level rapid aggregation proceeds. At all concentrations studied the synthetic glycolipids are incorporated in a unimodal fashion so that the observed threshold effects cannot be based on possible differences in the manner in which the glycolipids are incorporated at different concentrations. This conclusion is based on (1) studies with galactose oxidase that show that the percentage of galactose oxidation in a liposome prepared from a galactosyl-containing glycolipid is independent of glycolipid concentration, and (2) studies on the aggregation of liposomes containing mixed glycolipids in which the glycolipids are shown to behave independently. The importance of a critical density of membrane-bound receptors in order for aggregation to occur is discussed.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 94
    Electronic Resource
    Electronic Resource
    New York, N.Y. : Wiley-Blackwell
    Journal of Supramolecular Structure 11 (1979), S. 311-317 
    ISSN: 0091-7419
    Keywords: dynein ; flagella ; ATPase ; sperm motility ; sea urchin ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: A high-resolution sodium dodecyl sulfate polyacrylamide gel electrophoresis system has been used to show the presence, in both whole sperm and isolated flagellar axonemes, of eight polypeptides migrating in the 300,000-350,000 molecular weight range characteristic of the heavy chains of dynein ATPase. Previously, only five such chains have been discernible. Extraction of isolated axonemes for 10 min at 4°C with a solution containing 0.6 M NaCl, pH 7, releases a mixture of particles that separate, in sucrose density gradient centrifugation, into a major peak, dynein 1 ATPase, sedimenting at 21 S and a minor peak at 12-14S. The polypeptide compositions of these two peaks are different. The dynein 1 peak, which contains most of the protein on the gradient, contains approximately equal quantities of two closely migrating heavy chains, with a small amount of a third, more slowly migrating chain; no other heavy chains appear in this peak. Two groups of smaller polypeptides (three intermediate chains, within the apparent molecular weight range 76,000-122,000 and four newly discovered light chains, within the apparent molecular weight range 14,000-24,000) cosediment with the 21 S peak. The heavy chain composition of the 12-14S peak is more complex, all eight heavy chains occurring in approximately the same ratios as occur in intact axonemes.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 95
    Electronic Resource
    Electronic Resource
    New York, N.Y. : Wiley-Blackwell
    Journal of Supramolecular Structure 11 (1979), S. 339-347 
    ISSN: 0091-7419
    Keywords: switch hypothesis ; cilia ; motility ; vanadate ; calcium ; dynein ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Lateral (L) cilia of freshwater mussel (Margaritana margaritifera and Elliptio complanatus) gills can be arrested in one of two unique positions. When treated with 12.5 mM CaCl2 and 10-5 M A23187 they arrest in a “hands up” position, ie, pointing frontally. When treated with approximately 10 mM vanadate (V) they arrest in a “hands down” position, ie, pointing abfrontally. L-cilia treated with 12.5 mM CaCl2 and 1 mM NaN3 also arrest in a “hands down” position; substitution of 20 mM KC1 and 1 mM NaN3 causes cilia to move rapidly and simultaneously to a “hands up” position.The observations suggest that there are two switching mechanisms for activation of active sliding in ciliary beat one at the end of the recovery stroke and the other at the end of the effective stroke; the first is inhibited by calcium and the second by vanadate or azide. This is consistent with a model of ciliary beating where microtubule doublet numbers 1, 2, 3, and 4 are active during the effective stroke while microtubule doublets numbers 6, 7, 8, and 9 are passive, and the converse occurs during the recovery stroke.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 96
    Electronic Resource
    Electronic Resource
    New York, N.Y. : Wiley-Blackwell
    Journal of Supramolecular Structure 11 (1979), S. 429-444 
    ISSN: 0091-7419
    Keywords: (H++K+)-ATPase ; transport ATPase ; proton transport ; phospholipids ; phospholipase A2 ; CD spectrum ; gastric ATPase ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: The phospholipid and fatty acid composition and role of phospholipids in enzyme and transport function of gastric (H++K+)-ATPase vesicles was studied using phospholipase A2 (bee venom). The composition (%) was phosphatidylcholine (PC) 33%; sphingomyelin (sph) 25%; phosphatidylethanolamine (PE) 22%; phosphatidylserine (PS) 11%; and phosphatidylinositol (PI) 8%. The fatty acid composition showed a high degree of unsaturation. In both fresh and lyophilized preparations, even with prolonged incubation, only 50% of phospholipids were hydrolyzed, but the amount of PE and PS disappearing was increased following lyophilization. There was a marked decrease in K+-ATPase activity (75%) but essentially no loss of the associated K+ p-nitrophenyl phosphatase was found. ATPase activity could be largely restored by various phospholipids (PE 〉 PC 〉 PS). There was also an increase in Mg2+-ATPase activity, partially reversed in fresh preparations by the addition of phospholipids (PE 〉 PS 〉 PC). Proton transport activity of the preparation was rapidly inhibited, initially due to a large increase in the HC1 permeability of the preparation. Associated with these enzymatic and functional changes, the ATP-induced conformational changes, as indicated by circular dichroism spectra were inhibited.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 97
    Electronic Resource
    Electronic Resource
    New York, N.Y. : Wiley-Blackwell
    Journal of Supramolecular Structure 10 (1979), S. 365-375 
    ISSN: 0091-7419
    Keywords: ribosomes ; crystallization ; hypothermia ; chick embryos ; degeneration ; nuclei ; nucleolar extrusions ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Ribosome crystallization within nuclei has been studied in chick embryos with procedures which increase its frequency by various orders of magnitude as compared to previous findings. The extrusion of ribosome microcrystals from nuclei is reported for the first time, and a model for the transfer of ribosomes from nucleus to cytoplasm is proposed.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 98
    Electronic Resource
    Electronic Resource
    New York, N.Y. : Wiley-Blackwell
    Journal of Supramolecular Structure 10 (1979), S. 377-395 
    ISSN: 0091-7419
    Keywords: wet replicas ; microsurface spreading ; DNA ; subunits ; superbeads ; supercoils ; fibers ; chromosome bridges ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Superpacking of chromatin and the surface features of metaphase chromosomes have been studied by SiO replication of wet, unstained, and unfixed specimens in an exceedingly thin (≤ 1 nm) aqueous layer, keeping them wet. Hydrophilic Formvar substrates allow controlled thinning of the aqueous layer covering the wet specimens. Whole mounts of chromatin and chromosomes were prepared by applying a microsurface spreading method to swollen nuclei and mitotic cells at metaphase.The highest level of nucleosome folding of the inactive chromatin in chicken erythrocytes and rat liver nuclei is basically a second-order superhelical organization (width 150-200 nm, pitch distance 50-150 nm) of the elementary nucleosome filament. In unfavorable environments (as determined by ionic agents, fixative, and dehydrating agents) this superstructure collapses into chains of superbeads and beads. Formalin (10%) apparently attacks at discrete sites of chromatin, which are then separated into superbeads. The latter consist of 4-6 nucleosomes and seemingly correspond to successive turns of an original solenoidal coil (width 30-35 nm), which forms the superhelical organization. When this organization is unfolded, eg, in 1-2 mM EDTA, DNAse-sensitive filaments (diameter 1.7 nm) are seen to be wrapped around the nucleosomes.The wet chromosomes in each metaphase spread are held to each other by smooth microtubular fibers, 20-30 nm in diameter. Before they enter into a chromsome, these fibers branch into 9-13 protofilaments, each 5 nm wide. The chromosome surface contains a dense distribution of subunits about 10-25 nm in diameter. This size distribution corresponds to that of nucleosomes and their superbeads. Distinct from this beaded chromosome surface are several smooth, 23-30-nm-diameter fibers, which are longitudinal at the centromere and seem to continue into the chromatid structure. The surface replicas of dried chromosomes do not show these features, which are revealed only in wet chromosomes.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 99
    Electronic Resource
    Electronic Resource
    New York, N.Y. : Wiley-Blackwell
    Journal of Supramolecular Structure 10 (1979), S. 419-431 
    ISSN: 0091-7419
    Keywords: microtubules ; assembly ; protein-protein interactions ; electron microscopy ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Tubulin rings have been previously identified as composed of linear polymers of tubulin subunits, equivalent to a protofilament in the microtubule wall but in a curved rather than a straight conformation. We have examined and measured a number of different ring structures obtained under different conditions. The preferred curvature is indicated by a single ring of 380 Å outside diameter. Radially double rings consist of two coplanar rings of 460 Å and 350 Å outside diameter, held together by a pattern of eight identical contacts between the 40 Å subunits in the inner and outer rings. In some circumstances a larger ring, 570 Å diameter, can be added to the outside, or a smaller ring, 240 Å diameter, may be added to the inside of the radially double ring, in both cases repeating the pattern of eight radial contacts. The distortion of the filament from its relaxed 380 Å diameter curvature apparently can be made without disrupting the longitudinal bond between subunits in the filament, but must be stabilized by the energy of the radial contacts. All of these rings (single and radially double and triple) are observed to associate axially to form pairs or in some cases larger stacks. The radially double rings or an axially associated pair of these (quadruple ring) may also associate to form crystals. These are thin plates, up to 100 μm in extent and several μm thick which have been of limited use so far in diffraction studies because of irregularities in the packing of adjacent rings.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 100
    Electronic Resource
    Electronic Resource
    New York, N.Y. : Wiley-Blackwell
    Journal of Supramolecular Structure 11 (1979), S. 95-104 
    ISSN: 0091-7419
    Keywords: fibronectin structure and properties ; cytoskeleton ; cell surface proteins ; fibronectin distribution ; fibronectin interactions ; transformation ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Fibronectin is a large glycoprotein at the cell surface of many different cell types; a related protein is present in plasma. Fibronectin is a dimer of 230,000-dalton subunits and also occurs in larger aggregates; it forms fibrillar networks at the cell surface, between cells and substrata and between adjacent cells, and it is not a typical membrane protein. Cell surface fibronectin is reduced in amount or absent on transformed cells and in many cases its loss correlates with acquisition of tumorigenicity and, in particular, metastatic ability. Exceptions to the correlations with transformation and tumorigenicity exist. Loss of fibronectin and the resulting reduced adhesion appear to be involved in pleiotrpoic alterations in cell behavior and may be responsible for several aspects of the transformed phenotype in vitro. Fibronectin interacts with other macromolecules (collagen/gelatin, fibrin/fibrinogen, proteoglycans) and is apparently connected to microfilaments inside the cell.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...