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  • 11
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 200 (1963), S. 364-364 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Post-mitochondrial fractions from rat liver and three transplanted rat hepatomas were prepared and incubated anaerobically with glucose-6-phosphate under the conditions mentioned in the legend of Table 1. a-Glyeeroiphosphate was measured by the conventional enzymatic method2. Table 1 shows the ...
    Type of Medium: Electronic Resource
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  • 12
    ISSN: 1432-0983
    Keywords: Aspergillus niger ; Auxotrophic mutants ; Filtration enrichment ; Novozym enrichment ; Lytic enzymes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary More than 100 auxotrophic mutants of Aspergillus niger were isolated using filtration enrichment. The mutants obtained in this way were predominantly aminoacid requiring. Hardly any vitamin-deficient mutants were found. The limitations of the method turned out to be due to cross feeding in liquid medium and non-specific loss of ungerminated conidiospores. To circumvent these problems an enrichment method has been used in which conidiospores that germinated on solid medium were selectively killed by the lytic enzyme preparation Novozym 234. We found auxotrophic mutants at high frequencies and several new types of mutants. Optimal conditions for the enrichment procedures have been determined. Essential factors appeared to be segregation of the conidia after mutagenic treatment, in order to obtain synchronization of germination, and the incubation time of the conidia on minimal medium prior to enzymic treatment. Under appropriate conditions Novozym enrichment proved to be very efficient. Depending on the type of mutants desired, one or both procedures can provide an effective method for the enrichment of mutants with a metabolic defect. The Novozym method can be adapted to other fungi and some of the observations that are described may also be of importance to improve other enrichment methods that are based on the selective killing of germinating conidiospores.
    Type of Medium: Electronic Resource
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  • 13
    ISSN: 1432-0983
    Keywords: Transformation of Aspergillus ; Conidial protoplasts ; Multicopy/tandem integration ; Gene amplification
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Conidial protoplasts of an A. nidulans amdS deletion strain (MH1277) have been transformed to the AmdS+ phenotype with a plasmid carrying the wild type gene (p3SR2). Optimalisation of transformation and plating conditions now has resulted in frequencies of 300–400 transformants per μg of DNA. Analysis of DNA from AmdS+ transformants of MH1277 showed that transformation had occurred by integration of vector DNA sequences into the genome. In virtually all these transformants multiple copies of the vector were present in a tandemly repeated fashion, not preferentially at the resident, partially deleted amdS gene. It is suggested that the observed integration phenomena are dependent on the genetic background of the A. nidulans strain, used for transformation. A model to explain the tandem type of integration is proposed.
    Type of Medium: Electronic Resource
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  • 14
    Electronic Resource
    Electronic Resource
    Springer
    Journal of cancer research and clinical oncology 64 (1960), S. 52-63 
    ISSN: 1432-1335
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Mitochondrien aus Rattenlebern wurden 20–24 Std nach der Verabreichung einer akut-giftigen Menge DMNA (Dimethylnitrosamin) isoliert. Die Partikel wiesen eine sehr gesteigerte Neigung zur Schwellung und eine große Ähnlichkeit mit dem Verhalten von künstlich gealterten Mitochondrien auf. Die DMNA-Leberzellenmitochondrien sind also viel weniger stabil als normale. Dem entspricht auch eine gewisse funktionelle Labilität hinsichtlich gesteigerter ATP-Spaltung, verringerter P:O-ratio und Mangel an DPN-gekuppelten Oxydationen. Andere Äußerungen des toxischen Effektes des DMNA auf die Rattenleber, wie sie durch biochemische und elektronenmikroskopische Untersuchungen festzustellen sind, werden kurz besprochen und verglichen mit solchen nach wiederholter Fütterung kleinerer Mengen von DMNA während längerer Zeit. Während die Feinstruktur der Hauptmasse der Lebermitochondrien nach toxischen Dosen von DMNA unverändert blieb, war nun ein Verlust von Innenstruktur (sowohl Cristae wie Matrix) zu beobachten. In ausgesprochenem Gegensatz dazu war das Schwellungsverhalten aber vollkommen normal. Das doppelte Paradox (Normalstruktur/abnormale Schwellung; „abnormale” Struktur/normale Schwellung) wird zum Teil aufgehoben durch Experimente, welche auf die Möglichkeit hinweisen, daß die bei toxischen Dosen DMNA vermehrten nicht-strukturell gebundenen Fette in der Leber an Mitochondrien adsorbiert werden während ihre Isolierung, und diese schädigen könnten.
    Notes: Summary Mitochondria were isolated from the livers of rats 20–24 hours after the administration of an acutely toxic dose of DMNA. The particles showed a much increased tendency to swell in the assay systems described in the preceding papers, and closely resembled previously aged normal liver mitochondria. The conclusion was drawn that the DMNA-liver particles were much less stable than their normal counterparts. The latter conclusion was corroborated by the finding of a certain measure of functional lability of the particles: increased ATP-splitting, decreased P:O ratios and some deficiency in DPN-linked oxidations. Other manifestations of the toxic effect of DMNA on rat liver, revealed by biochemical and electron microscopic examinations, are briefly discussed and compared with those observed after repeated administration of low doses of DMNA during prolonged periods. Pertinent to the present study was the finding that the fine structure of the major part of liver mitochondria following the toxic dose of DMNA was not altered, whereas after prolonged administration of DMNA in low amounts some loss of internal structure (both cristae and matrix) was observed. In sharp contrast to this observation stood the finding that the in vitro pattern of swelling of the latter particles was completely normal. The double paradox (normal structure/abnormal swelling; ‘abnormal’ structure/normal swelling) was partly resolved by the results of experiments which pointed to the possibility that the non-structurally-bound fats, accumulated in livers of rats following the toxic dose of DMNA, might become adsorbed onto the mitochondria during their isolation, and afflict damage.
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  • 15
    Electronic Resource
    Electronic Resource
    Springer
    Journal of cancer research and clinical oncology 64 (1960), S. 22-34 
    ISSN: 1432-1335
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Die Schwellung von in 0,30 M Saccharose isolierten und in Saccharose-Tris von pH 7,4 bei 22±1°C inkubierten Mitochondrien aus Mäuse- und Rattenlebern wurde gemessen nach Zusatz von Succinat, Adeninnucleotiden (10−5 M), Malonat, Thyroxin und DNP, allein und in verschiedenen Kombinationen. Sowohl die spontane wie die thyroxininduzierte Schwellung frischer Mitochondrien wird durch Succinat und noch mehr durch Succinat und Adeninnucleotide (ADP≥ATP≫ oder 〉 AMP) gehemmt. Die Hemmung wird aufgehoben durch Malonat oder DPN. Auf die Hemmung der Schwellung von frischen Mitochondrien durch Succinat folgt eine Phase schneller Schwellung. Allmähliche Alterung oder wiederholte Waschungen von den Mitochondrien vor der Inkubation führen zu einer Verringerung oder Aufhebung des hemmenden Effektes des Succinats. Daraus wird gefolgert, daß die mitochondriale Schwellung von dem Grade der Eigenstabilität der isolierten Partikel abhängig ist.
    Notes: Summary The swelling of rat and mouse liver mitochondria, isolated in 0.30 M sucrose and incubated in sucrose-Tris of pH 7.4 at 22±1°C, in response to succinate, adenine nucleotides (10−5 M), malonate, thyroxine, and DNP, separately or in various combinations, was measured. It was found that both the spontaneous and thyroxine-induced swelling of fresh mitochondria were counteracted by succinate and, to a still greater extent, by succinate plus adenine nucleotide (ADP≥ATP≫ or 〉 AMP). The protection was abolished by malonate or DNP. The protection against swelling afforded by succinate to fresh mitochondria was followed by a phase of rapid swelling. Progressive ageing or frequent washing of the particles, prior to their incubation, led to a reduction or abolition of the protective effect. It was concluded that mitochondrial swelling was governed by the degree of intrinsic stability of the isolated particles.
    Type of Medium: Electronic Resource
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  • 16
    Electronic Resource
    Electronic Resource
    Springer
    The journal of membrane biology 9 (1972), S. 83-104 
    ISSN: 1432-1424
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary Plasma membranes were isolated under hypotonic conditions from rat and mouse livers and five hepatomas, i.e. one rather anaplastic rat hepatoma (and its subline) and three well-differentiated mouse hepatomas. All these membranes contained some 25% protein soluble in 0.15m NaCl. Evidence is presented that this protein is mainly, if not exclusively of nonmembranous origin. Protein/phospholipid P (P=phosphorus) ratios did not differ significantly for the various plasma membrane species except the rat-hepatoma subline, which showed a markedly lower ratio and was thus identified. Hepatoma membranes contained more P of a nonphospholipid nature than did liver membranes and to this increase contributed in all instances an increased RNA content and in some cases also an increased DNA content. The presence of DNA in these plasma membranes is artefactual, but that of RNA is more complicated. Artefactually, Ca2+-associated RNA of low mol wt and soluble in 0.15m NaCl, and residual RNA (genuine?, in liver membranes less than 1% in respect of protein) have been demonstrated. The increase in hepatoma-membrane RNA is attributed to the ribosomal RNA of the few microsomal vesicles which are structurally connected with these plasma membranes. The sialic acid content and the percentage of neuraminidase-resistant sialic acid of hepatoma as compared with liver membranes was either similar or changed, depending on the hepatoma strain. Gelfiltration of trypsin-released peptides of liver plasma membranes showed hexosamine and hexose to be confined to the sialic acidcontaining fractions. In spite of quantitative differences among fractions, the relative contents of the three carbohydrates in the combined fractions were (about) similar to those in intact liver membranes. Similar experiments with the rat-hepatoma membranes showed a changed carbohydrate expression.
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  • 17
    Electronic Resource
    Electronic Resource
    Springer
    Genetica 48 (1978), S. 239-240 
    ISSN: 1573-6857
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Type of Medium: Electronic Resource
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  • 18
    Electronic Resource
    Electronic Resource
    Springer
    Genetica 41 (1970), S. 638-641 
    ISSN: 1573-6857
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Type of Medium: Electronic Resource
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  • 19
    Electronic Resource
    Electronic Resource
    Springer
    Genetica 37 (1966), S. 601-606 
    ISSN: 1573-6857
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Type of Medium: Electronic Resource
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  • 20
    Electronic Resource
    Electronic Resource
    Springer
    Antonie van Leeuwenhoek 48 (1982), S. 219-227 
    ISSN: 1572-9699
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Several mutants Aspergillus nidulans defective in carbohydrate metabolism were tested for growth on different carbon sources. d-Galacturonate was found to be a substrate, useful to discriminate between mutants in pyruvate kinase, pyruvate dehydrogenase complex or pyruvate carboxylase. The results of these tests indicate how particular classes of mutants can be obtained and which substrates can be used preferentially for a rapid phenotypical screening of unknown mutants.
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