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  • 1
    Electronic Resource
    Electronic Resource
    Ornithine cycle in Nostoc PCC 73102. Arginase, OCT and arginine deiminase, and the effects of addition of external arginine, ornithine, or citrulline (1993)
    Springer
    Archives of microbiology 159 (1993), S. 506-511 
    Details
    ISSN: 1432-072X
    Keywords: Arginase ; Arginine deiminase ; Cyanobacterium ; Nitrogenase activity ; Nostoc ; Ornithine carbamoyl transferase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Arginase, ornithine carbamoyl transferase (OCT) and arginine deiminase activities were found in cell-free extracts of Nostoc PCC 73102, a free-living cyanobacterium originally isolated from the cycad Macrozamia. Addition of either arginine, ornithine or citrulline to the growth medium induced significant changes in their in vitro activities. Moreover, growth in darkness, compared to in light, induced higher in vitro activities. The in vitro activities of arginase and arginine deiminase, two catabolic enzymes primarily involved in the breakdown of arginine, increased substantially by a combination of growth in darkness and addition of either arginine, or ornithine, to the growth medium. The most significant effects on the in vitro OCT activities where observed in cells grown with the addition of ornithine. Cells grown in darkness exhibited about 6% of the in vivo nitrogenase activity observed in cells grown in light. However, addition of external carbon (glucose and fructose) to cells grown in darkness resulted in in vivo nitrogenase activity levels similar to, or even higher than, cells grown in light. Growth with high in vivo nitrogenase activity or in darkness with the addition of external carbon, resulted in repressed levels of in vitro arginase and arginine deiminase activities. It is suggested that nitrogen starvation induces a mobilization of the stored nitrogen, internal release of the amino compound arginine, and an induction of two catabolic enzymes arginase and arginine deiminase. A similar and even more pronunced induction can be observed by addition of external arginine to the growth medium.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00249027
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  • 2
    Electronic Resource
    Electronic Resource
    Ornithine cycle in Nostoc PCC 73102: presence of an in vitro functional argininosuccinate lyase (1997)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 152 (1997), S. 0 
    Details
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The presence of argininosuccinate lyase (ASL), an enzyme catalyzing the final step of arginine biosynthesis, was demonstrated in the heterocystous cyanobacterium Nostoc PCC 73102 by measuring in vitro enzyme activity and by visualization of ASL in native protein gels. Activity staining of a native PAGE gel revealed one ASL-dependent band with a molecular mass of about 240 kDa. A colorimetric assay for ASL based on the measurement of urea produced from arginine in the presence of an excess of arginase was further used to analyze the cyanobacterial ASL. The in vitro ASL activity was highest in cells in exponential growth phase and decreased significantly during the stationary phase of growth, ranging from 4.4 to 0.8 nmol of product formed (mg protein)−1 min−1. Including arginine, citrulline or ornithine in the growth medium resulted in no significant change in the ASL activities, indicating that Nostoc PCC 73102 ASL is not regulated by metabolites of the ornithine cycle.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-6968.1997.tb10411.x
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  • 3
    Electronic Resource
    Electronic Resource
    Duration of protective immunity and antibody titres measured by ELISA after vaccination of rainbow trout, Salmo gairdneri Richardson, against vibriosis (1987)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of fish diseases 10 (1987), S. 0 
    Details
    ISSN: 1365-2761
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Abstract. The level of protective immunity in rainbow trout, Salmo gairdneri Richardson, following vaccination by intraperitoneal (i.p.) injection or by direct immersion with Vibrio anguillarum was studied over a period of 46 weeks. Antibody titres to V. anguillarum O-antigen were determined with ELISA at the time of each experimental infection to study the relation between specific antibody production and protective immunity. Both vaccination by i.p. injection and vaccination by direct immersion induced a high degree of protective immunity against vibriosis which lasted for at least 46 weeks. At each experimental infection, the proportions of seropositive fish were lower than the proportions of fish with protective immunity. However, seropositive individuals were found in both experimental groups throughout the study.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2761.1987.tb01099.x
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  • 4
    Electronic Resource
    Electronic Resource
    Cloning and molecular characterization of a presumptive argF, a structural gene encoding ornithine carbamoyl transferase (OCT), in the cyanobacterium Nostoc sp. PCC 73102 (1998)
    Copenhagen : Munksgaard International Publishers
    Physiologia plantarum 103 (1998), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Ornithine carbamoyl transferase (OCT), encoded by argF, catalyzes the formation of citrulline from ornithine and carbamoyl phosphate. A presumptive argF from the filamentous cyanobacterium Nostoc sp. PCC 73102 has been cloned and sequenced. A transcriptional terminator sequence is suggested downstream of the structural gene. Amino acids known to be involved in binding the substrate carbamoyl phosphate and ornithine were observed within the sequence. The deduced amino acid sequence showed 69% identity to the deduced amino acid sequence from Synechocystis sp. PCC 6803, but less identities (30-46@) to OCTs from other organisms. The subunits of the deduced protein had a calculated molecular mass of 33 368 Da. Northern blot experiments demonstrated a single transcript with an approximate size of 0.95 kb.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1034/j.1399-3054.1998.1030307.x
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  • 5
    Electronic Resource
    Electronic Resource
    Effect of the crown on uptake and transport in embryonic shoots of Picea abies (1983)
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 59 (1983), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Embryonic shoots of Picea abies (L.) Karst, isolated from 10-year-old trees, were excised either with or without the crown. Various short-term uptake experiments (3, 6 and 24 h) and one long-term uptake experiment (4 weeks) were performed with these shoots to obtain information about the physiological role of the crown as translocation barrier for different substances. Transport through the embryonic shoots was followed in both acropetal and basipetal directions using radiolabelled substances supplied in an agarified Schenk and Hildebrandt medium. The medium was labelled with [14C]-IAA and/or [32P]-phosphate, or with [35S]-sulphate and 86Rb (as a tracer for K+). The experiments were conducted in light at 20°C, with the exception of one of the short-term experiments, which was carried out at 5°C to evaluate the connection between transport and metabolism. The main observation is that the crown in its collenchymatous stage of development acts as a selective barrier both acropetally and basipetally for transport of substances such as [14C]-IAA and [32P]-phosphate or their metabolized forms. This could explain why the embryonic shoot when cultured plus or minus its crown shows different growth and developmental patterns in vitro.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1399-3054.1983.tb06274.x
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  • 6
    Electronic Resource
    Electronic Resource
    Morphogenesis in dormant embryonic shoots of Picea abies: Influence of the crown and cold treatment (1983)
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 59 (1983), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Retention of the crown, a plate of homogeneously thickened collenchymatous cells at the base of the embryonic shoot of Picea abies (L.) Karst., has marked effects on the induction of adventitious buds from the needle primordia. These effects were observed on embryonic shoots of three clones which were cold-treated at 4 ± 1°C for nil, two, four and six months; and then excised either with or without the crown, before subculturing either directly on a medium lacking plant growth regulators or after application of 125 μM benzyladenine (BA) as a 3-h pulse. Embryonic shoots retaining the crown and treated with BA responded reproducibly better than those lacking it. This was true both for the number of shoots that produced adventitious buds and for the numbers of adventitious buds per shoot. Differentiation of as many as five adventitious buds in a single needle primordium was observed, with development occurring nearly twice as early (7 as compared with 12 weeks) in the presence as in the absence of the crown. The response decreased progressively with increasing exposure to cold treatment.A number of anatomical changes occurred during culture in vitro. After 3 to 4 weeks a band of sclerenchymatous cells commenced differentiation at the centre of the crown. In embryonic shoots without the crown, a tissue which was identified as a wound periderm formed at the excision surface. Vascular unions were observed between the tissues of the newly — formed shoots induced from the needle primordia and those of the original shoot explants.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1399-3054.1983.tb06562.x
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  • 7
    Electronic Resource
    Electronic Resource
    In vitro phyllomorphic regeneration of shoot buds and shoots in Picea abies (1980)
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 49 (1980), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Needles (10–15 mm) of frost-hardened 20–22-week-old (physiological age equivalent to 1 year) plants of Picea abies L. excised just after flushing, were induced to form adventitious shoot buds and shoots on media supplemented with BAP (6-benzylaminopurine) and NAA (1-napthaleneacetic acid). The addition of nanomolar concentrations (0.5–50) of NAA combined with 1–10 μM BAP considerably stimulated formation of pseudobulbils on the basal to mid-part of the needle axis, as well as their subsequent development into shoot buds and shoots. On a medium containing 10 μM BAP, pseudobulbils that formed at the needle base did not develop further, but became necrotic and died with the omission of NAA. With 5 μM BAP + 50 nM NAA the initial phase of development was slow, but later showed good response and up to 22% of the needles produced shoot buds. Two to three shoots per needle could be excised and subcultured individually onto fresh media. It is concluded that the level of endogenous auxin decreases progressively from the needle's base to its tip, so that that concentration of exogenous auxin (50 nM NAA) which promotes pseudobulbil and shoot-bud formation part-way along the needle axis, simultaneously inhibits their induction at the needle base.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1399-3054.1980.tb08656.x
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  • 8
    Electronic Resource
    Electronic Resource
    Coumarin effects on Glycine max hypocotyl explants (1980)
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 48 (1980), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Coumarin induced root formation and stimulated fresh weight production in hypocotyl explants of Glycine max L. cultured in vitro. All stimulatory effects caused by coumarin were induced within a relatively narrow range of concentrations between 1–500 μM, yielding optimum dose response curves. When coumarin was combined with kinetin fresh weight increased considerably, at optimum concentrations to a level almost as high as that obtained with NAA (10 μM) and kinetin (10 μM). Root formation was almost completely inhibited when kinetin was added in combination with coumarin. NAA + coumarin had small stimulatory effects on fresh weight. but were inhibitory in root formation. The frequency of rooting per explant, texture and pigmentation were also affected by different treatments.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1399-3054.1980.tb03291.x
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  • 9
    Electronic Resource
    Electronic Resource
    In vitro initiation of adventitious structures in relation to the abscission zone in needle explants of Picea abies: anatomical considerations (1981)
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 53 (1981), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: A comparison of the regeneration potential of needles of different ages in Picea abies emphasized the importance of taking into account the manner of explantation as well as the state of differentiation of the abscission zone. Generally, response in terms of initiation of adventitious structures decreased progressively not only with needle age (5 to 10 to 15 mm long) but also with the distance from the abscission zone towards the tip, that is, distally. On a bud-induction medium adventitious shoot but primordia were produced proximally and distally (except for the very tip) of the weakly-developed abscission zone in needles ca. 5 mm and shorter. In needles between 5 and 10 mm long the various cell types of the abscission zone commenced differentiation, and adventitious structures (shoot bud and other primordia) were formed proximal and immediately distal to it. In needles ca. 15 mm long, in which the abscission zone's hyaline, separation and protective layers became well-developed and where senescence of the distal part commenced, response was limited to proximal tissues. Divisions giving rise to adventitious primordia distal to the abscission zone arose from epidermal cells proper and, in a more acropetal position, also from subsidiary cells of the stomata. Cells of the hypodermis contributed only in the near-distal region of the abscission zone in younger needles, and before commencing differentiation into fibres.When excised carefully, the explant consists of a leaf plus a peg-like cushion of axillary, meristematic tissue proximal to the abscission zone and capable of ready regeneration. In view of the apparent relationship between age and the stage of development of the abscission zone, it was concluded that there exists a critical needle length which should not be exceeded when attempting in vitro induction of organ primordia.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1399-3054.1981.tb04132.x
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  • 10
    Electronic Resource
    Electronic Resource
    Nicotiana tabacum callus studies. X. ABA increases resistance to cold damage (1980)
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 48 (1980), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The effects of cis. trans abscisic acid on response to chilling was investigated in callused Nicotiana tabacum L. pith explants. Explants pretreated with 10-4M ABA underwent approximately 50% less cellular leakage when chilled at 2°C under short-day conditions for 10 d than the comparable non-treated tissue. Growth in terms of fresh and dry weights, although poor in comparison to non-chilled (20°C, long days) treatments, was more than twice that of the non-ABA-treated material. On an absolute dry weight basis proline content increased on chilling from 0.7 to 3.4 mg g-1 in non-ABA-treated explants, but rose to nearly 17 mg g-1 in the tissue treated with ABA. Only in the case of cold-hardened. ABA-treated tissue could some cells survive subzero temperatures and regenerate callus again. It is suggested that at least part of the ameliorating effects of ABA result from an increase in the level of proline.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1399-3054.1980.tb03292.x
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