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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Algorithmica 1 (1986), S. 409-424 
    ISSN: 1432-0541
    Keywords: Linear programming ; Karmarkar's algorithm ; Duality
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: Abstract We describe an extension of Karmarkar's algorithm for linear programming that handles problems with unknown optimal value and generates primal and dual solutions with objective values converging to the common optimal primal and dual value. We also describe an implementation for the dense case and show how extreme point solutions can be obtained naturally, with little extra computation.
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Archives of environmental contamination and toxicology 14 (1985), S. 167-177 
    ISSN: 1432-0703
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Medicine
    Notes: Abstract A multispecies-multitoxicant defined microcosm was studied by examination of its various components. Determination of population interactions showed thatChlorella vulgaris inhibitedAnkistrodesmus braunii by 32%. The presence ofChromobacterium violaceum resulted in a further inhibition ofA. braunii (17%) but its presence had no effect onC. vulgaris. Sensitivity of the two algae and the bacterium were determined for the toxicants atrazine1 and sodium pentachlorophenate, both singly and in combination. While both algae were sensitive to the toxicants, the combined effect of the toxicants on the individual populations was additive. In mixed cultures with one toxicant present, a synergistic interaction was detected between sodium pentachlorophenate andC. vulgaris with respect to A.braunii. Further, the combination ofA. braunii and atrazine withC. vulgaris resulted in an increased inhibition ofC. vulgaris. These observations indicate that biological-chemical interactions can occur as do population-population and chemical-chemical interactions. When mixed cultures of the algae were treated with both toxicants, chemical antagonism was observed. This antagonism was modified by the presence of the bacterium but it was not eliminated. It was concluded that the techniques allowed determination of the interactions in a complex microcosm.
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Histochemistry and cell biology 85 (1986), S. 505-514 
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary This study examined the detection of cellular poly(A) sequences in mouse liver sections by in situ hybridization using a 3H-labelled poly(dT) probe. Parameters examined included possible losses of target poly(A) sequences from sectioned cells, access of probe to target sequences, section thickness, hybridization conditions, autoradioigraphic efficiency, specific activity of probes and specificity of reaction. An improved protocol was devised that resulted in good preservation of histological detail in sectioned tissue blocks, and a calculated hybridization efficiency of 50%–100%. With the use of probes of defined sequence, the protocol should allow detection of unique mRNA sequences within single cells with an estimated sensitivity of 6–12 unique mRNA molecules per sectioned cell.
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    World journal of microbiology and biotechnology 1 (1985), S. 247-256 
    ISSN: 1573-0972
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Description / Table of Contents: Résumé Les croissances hétérotrophes et photohétérotrophes des algues vertesChlorella vulgaris etAnkistrodesmus braunii ont été étudiées comparativement en mesurant la croissance et en établissant des bilans carbonés. A partir de deux estimations distinctes de l'efficacité globale, consistant dans les rapports CO2 produit sur substrat utilisé et carbone cellulaire sur carbone métabolisé, il a été conclu que les deux micro-organismes sont photo-hétérotrophes, mais queC. vulgaris est plus efficace queA. braunii. La distribution du carbone a été déterminée par les bilans carbonés. Après onze jours de croissance à la lumière, les quantités de substrat carboné retrouvées dans la biomasse cellulaire deC. vulgaris et deA. braunii sont respectivement de 97 et 76%. Les voies fermentatives paraissent être présentes chez les deux microorganismes, et cela surtout à l'obscurité et dans les vieilles cultures, comme l'indique la perte apparente de carbone sous forme de composés organiques volatils. Les résultats obtenus avec les deux micro-organismes étudiés démontrent que les algues vertes sont capables de convertir photo-hétérotrophiquement et hétérotrophiquement une proportion élevée de la matière organique en biomasse. De ce fait, les étangs à taux d'oxydation élevée devraient être considérés du point de vue de l'exploitation de leur potentiel hétérotrophe.
    Abstract: Resumen Se examinó y comparó el crecimiento heterótrofo y fotoheterótrofo midiendo crecimiento y presupuestos para el carbono de las siguientes algas verdes:Chlorella vulgaris y Ankistrodesmus braunii. La eficiencia general se estimó mediante dos parámetros: el cociente entre CO2 suministrado y CO2 fijado por el sustrato, y el cociente entre carbono celular y carbono del sustrato utilizado. Apartir de estas medidas se concluyó que ambos micro-organismos eran capaces de fotoheterotrofia aunqueC. vulgaris era más eficiente queA. braunii. Los presupuestos para la masa carbonada mostraron la distribución del carbono. Después de 11 días de crecimiento en presencia de luz el 97 y el 76% de la glucosa del sustrato se había transformado en biomasa celular enC. vulgaris y enA. braunii respectivamente. En ambos microorganismos parecieron funcionar vías fermentativas, especialmente en la oscuridad y en cultivos viejos, como se vio indicado por la aparente pérdida de carbono en formo de compuestos orgánicos volátiles. Los resultados obtenidos demuestran la habilidad de las algas verdes para convertir tanto fotoheterótrofa como heterótroficamente una elevada proporción de sustratos orgánicos en biomasa. Las balsas con una elevada demanda de oxigeno deberian, pues, de ser consideradas bajo una perspectiva heterótrofa con vistas a la explotación de dicho potencial heterótrofo.
    Notes: Summary Heterotrophic and photoheterotrophic growth of the green algaeChlorella vulgaris andAnkistrodesmus braunii were examined and compared through growth measurements and mass carbon budgets. Using two different estimates of overall efficiency, based upon the ratios of CO2 evolved to substrate taken up and cellular carbon to substrate carbon utilized, it was concluded that both micro-organisms were capable of photoheterotrophy althoughC. vulgaris was more efficient thanA. braunii. Mass carbon budgets showed the distribution of carbon. After 11 days of growth in the light, 97 and 76% of the glucose substrate was accounted for as cell biomass forC. vulgaris andA. braunii respectively. Fermentation pathways appeared to function in both micro-organisms, particularly in the dark and in ageing cultures, as indicated by the apparent loss of carbon as volatile organics. The results obtained with the two micro-organisms studied demonstrate the ability of green algae to photoheterotrophically and heterotrophically convert a high proportion of an organic substrate into biomass. Thus, high-rate oxidation ponds should be considered from a heterotrophic perspective with a view to exploiting this heterotrophic potential.
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Theoretical and applied genetics 70 (1985), S. 440-446 
    ISSN: 1432-2242
    Keywords: Agrobacterium rhizogenes ; Potato ; Somaclonal variation ; Genetic manipulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Forty-two potato plants were regenerated from a hairy-root line obtained after infection of a shoot of Solanum tuberosum cv ‘Desiree’ with Agrobacterium rhizogenes strain LBA 9402 (pRil855). Transformed plants were uniform and had a distinct phenotype and development compared with untransformed controls. Their growth was vigorous, especially early in their development, their roots were abundant and showed reduced geotropism, their leaves were slightly crinkled and glossy and they produced longer tubers with more frequent, prominent eyes. Cytological examination showed that ten of the forty-two transformed plants had either 47 or 49 chromosomes instead of the normal 48. In two of these aneuploids structural changes were observed.
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Theoretical and applied genetics 71 (1985), S. 325-329 
    ISSN: 1432-2242
    Keywords: A. tumefaciens ; A. rhizogenes ; Brassica napus ; Plant development
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The response of oilseed rape cultivars to infection with Agrobacterium tumefaciens and A. rhizogenes and the possibility of regenerating genetically transformed oilseed rape plants were examined. The frequency at which Agrobacterium induced galls or hairy-roots on in vitro cultured plants ranged from 10% to 70%, depending on the cultivar. From galls induced by the tumorigenic strain T37, known to be strongly shoot inducing on tobacco, roots developed frequently. Occasionally, shoots formed and some of these produced tumour cell specific nopaline. Attempts to grow the transformed shoots into plants have so far been unsuccessful. Whole plants transformed with Ri-T-DNA, however, were regenerated. These had crinkled leaves and abundant, frequently branching roots that showed reduced geotropism, similar to previously isolated Ri T-DNA transformed tobacco and potato plants. The transformed oilseed rape plants flowered, but failed to form seeds.
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Theoretical and applied genetics 73 (1987), S. 744-750 
    ISSN: 1432-2242
    Keywords: Genetic manipulation ; Neomycin phosphotransferase ; Mixed infection ; Somaclonal variation ; Solanum tuberosum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Derivatives of potato (Solanum tuberosum cv.'s ‘Maris Bard’ and ‘Desiree’) transformed with disarmed T-DNA from genetically engineered Agrobacterium tumefaciens strains were isolated. The transformed plants were recovered from shoot-forming tumours induced by infection of wounds with mixedcultures of shoot-inducing A. tumefaciens strains T37 and either Agrobacterium strain LBA1834(pRAL1834), (Hille et al. 1983) or LBA4404(pBIN6; pRAL4404), (Bevan 1984). Two small-scale feasibility experiments gave at least four ‘Maris Bard’ plants transformed with pRAL1834 T-DNA and two ‘Desiree’ plants with pBIN6 T-DNA. The transformed ‘Maris Bard’ plants were morphologically abnormal and highly aneuploid. This was probably an unfortunate side-effect of a tissue culture-step introduced to promote the efficiency of shoot regeneration. The transformed ‘Desiree’ plants, in contrast, were isolated without promoting additional shoot-growth. They were morphologically normal, contained 47 and the euploid 48 chromosomes per cell respectively and had improved growth on media containing kanamycin.
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Potato research 29 (1986), S. 367-379 
    ISSN: 1871-4528
    Keywords: hairy-root ; Ri-plasmid ; T-DNA ; potato cultivars ; in vitro culture ; field experiments
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Description / Table of Contents: Zusammenfassung Infektion verwundeter Stengel in vitrogewachsenen Kartoffelsorten hatte lokale, proliferierende Wurzelbildung (haarige Wurzeln; Abb. 2A) zur Folge. Diese Wurzelzellen enthielten neu eingebrachte DNA, die nicht in normalen Kartoffeln entdeckt werden konnte, sondern aufA. rhizogenes zurückzuführen ist (Mechanismen vgl. Abb. 1). Einzelne umgebildete Wurzeln der Sorten Majestic, Record und Maris Bard wurden zu ganzen Pflanzen regeneriert (Abb. 2B, C). Die meisten der transformierten Pflanzen waren euploid (2n=4x=48; Abb. 2D). Der Ausdruck der eingebrachten Gene ergab stabile Veränderungen bei Pflanzenentwicklung und Knollengestalt (Abb. 2E), welche auch unter Feldbedingungen erhalten blieben (Abb. 2F, 3 und Tabelle 1). Daraus wurde geschlossen, dass (1) vermutlich jede kommerzielle Kartoffelsorte unter entsprechenden BedingungenAgrobacterium-vermittelter genetischer Veränderung zugänglich ist; (2) die vonA. rhizogenes abstammenden Gene konventionelle Modellgene zum Studium des Ausdrucks von Struktur, Kontrolle und Stabilität transferierter Gene sind; und (3) vonA. rhizogenes abstammende Gene von potentiellem Nutzen zum Studium des Einflusses spezifischer genetischer Faktoren auf komplexer biologischer Prozesse wie Knollenentwicklung und Knollenbildung sind. Vielleicht können Gene, wie die vonA. rhizogenes abgeleiteten T-DNA-Gene, welche kontrollierenden Einfluss auf die Pflanzenentwicklung und Knollenbildung zeigen, zur Hervorbringung von nützlichen Änderungen, die für bestimmte Kartoffellinien von Nutzen sind, verwendet werden.
    Abstract: Résumé L'infection de tiges blessées de variétés de pommes de terre cultivées in vitro avecAgrobacterium rhizogenes a causé une prolifération localisée de racines (racines chevelues, Fig. 2A). Les cellules de ces racines contenaient du DNA nouvellement introduit, non décelable chez la pomme de terre non infectée, provenant deA. rhizogenes (pour le mécanisme voir Fig. 1). De simples racines modifiées génétiquement, issues des variétés Majestic, Record et Maris Bard, régénéraient des plantes entières (Fig. 2B-C). La plupart des plantes régénérées étaient euploïdes 2n=4x=48 (Fig. 2D): les gênes introduits s'exprimaient par des modifications stables au niveau du développement de la plante et de la forme des tubercules (Fig. 2E), même dans les conditions du champ (Fig. 2F, 3 et tableau 1). On en concluait que (i) probablement n'importe quelle variété commerciale cultivée dans des conditions appropriées peut être soumise à des manipulations avecAgrobacterium comme médiateur; (ii) les gênes provenant deA. rhizogenes sont des modèles génétiques possibles pour étudier les questions concernant la structure, le contrôle et la stabilité de l'expression des gênes transférés. En outre, (iii) les gênes provenant d'A. rhizogenes constituent un matériel potentiel pour étudier l'influence des facteurs génétiques spécifiques sur des processus biologiques complexes tels que la croissance et la tubérisation de la pomme de terre. Peut être que des gênes semblables aux gênes T-DNA deA. rhizogenes ont une influence sur le développement de la plante; peut être aussi que leur introduction occasionnerait des modifications bénéfiques, en particulier pour les lignées de pomme de terre.
    Notes: Summary Infection withAgrobacterium rhizogenes of wounded stems of potato cultivars grown in vitro caused localized prolific root formation (hairy-roots). The cells of these roots contained newly introduced DNA, not detected in normal potato, that was derived fromA. rhizogenes. Single transformed roots from the cultivars Majestic, Record and Maris Bard were regenerated into whole plants. Expression of the introduced genes caused stable alterations in plant development and tuber shape, which were retained under field conditions. The following conclusions were reached. (i) Probably any commercial potato cultivar, cultured under appropriate conditions, is amenable toA. rhizogenes-mediated genetic manipulation. (ii) TheA. rhizogenes-derived genes are convenient model genes for studying questions on structure and expression of transferred genes. (iii) A. rhizogenes-derived genes are of potential use to study the influence of specific genetic factors on complex biological processes such as potato development and tuberization.
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  • 9
    ISSN: 1573-5028
    Keywords: Agrobacterium tumefaciens ; gene expression ; potato ; T-DNA
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary In potato line Mb1501B one or possibly two normal size Ti TL-DNA copies per tetraploid genome were detected by Southern blot analysis, but no TR-DNA. The TL-DNA probably contained the entire transposon Tn1831 inserted at the T-DNA auxin gene for transcript 2. Northern blot analyses of the steady-state RNA in different Mb1501B tissues isolated from (i) shoots cultured in vitro (ii) grafted plants and (iii) tubers, showed that that TL-DNA transcripts 3, 4, 6a and 7 were expressed most abundantly in the cultured shoots. They formed approximately 0.0023 to 0.0007% of the total poly(A) RNA. Transcripts 1, 5 and 6b were not detected in any of the tissues analysed. This indicated even lower levels of expression (below approximately 0.0001% of the total poly(A) RNA or, making certain assumptions, an abundance of less than one T-DNA derived RNA molecule per cell). As expected, transcript 2 was not detected in any of the Mb1501B tissues. The abundance of the transcripts was reduced in grafted plants and tubers compared with cultured shoots with the greatest decrease (5×) for transcripts 4, 6a and 7. Transcript 4, the one most responsible for the changed growth and development of Mb 1501 B, formed approximately 0.0003% of the poly(A) RNA from both grafted plants and tubers.
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  • 10
    ISSN: 1573-5028
    Keywords: Crown gall ; cytokinins ; in vitro translation ; poly(A) RNA ; potato ; T-DNa
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Two dimensional gel electrophoresis was used to examine differences in steady state total poly(A) RNA from untransformed potato (Solanum tuberosum cv. Maris Bard) and potato transformed with shoot-inducing TL-DNA from A. tumefaciens. RNA was compared from phenotypically very distinct in vitro cultured shoots, more similar grafted plants and tubers. In each case between 200–400 translation products were identified representing the more abundant poly(A) mRNA's. In general, poly(A) RNA from the transformed tissues gave more high molecular weight products. This increase was most evident in poly(A) RNA from shoot cultures. Depending on the tissue examined, 1–5% of the translation products with a molecular weight 〈43 KD were observed to increase or decrease in abundance. The influence of T-DNA on cellular gene expression in the different transformed potato tissues is discussed in relation to previously determined changes in T-DNA gene expression (particularly of the T-DNA cytokinin gene) and the corresponding changes in endogenous hormone concentrations. It is concluded that some of the specific changes in low molecular weight products are either directly caused by the increased cytokinin levels or are indirectly involved in maintaining the transformed phenotype. re]19850530 rv]19851206 ac]19851210
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