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  • risk assessment
  • somaclonal variation
  • tissue culture
  • Springer  (42)
  • American Chemical Society
  • American Meteorological Society
  • Cambridge University Press
  • 1995-1999
  • 1990-1994  (42)
  • 1992  (42)
  • 1966
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  • Springer  (42)
  • American Chemical Society
  • American Meteorological Society
  • Cambridge University Press
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Erscheinungszeitraum
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  • 1
    Digitale Medien
    Digitale Medien
    Springer
    Plant cell reports 11 (1992), S. 66-70 
    ISSN: 1432-203X
    Schlagwort(e): Phytolacca dodecandra ; endod ; ribosomeinactivating protein ; dodecandrin ; tissue culture
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Leaves and stems from endod (Phytolacca dodecandra L'Herit), known to produce the 29 kDa ribosome-inactivating protein (RIP) dodecandrin, were initiated into tissue culture. Callus and suspension cultures were maintained on modified Murashige and Skoog medium plus 1.0 mg/l 2,4-dichlorophenoxyacetic acid. Six callus and two suspension cell lines were screened for dodecandrin production by western blots with affinitypurified antiserum. Antiribosomal activity of culture extracts was tested by in vitro translation assays. One suspension cell line was found to be free of immunoreactive proteins and a ribosome inhibitor. All other cell lines contain a ribosome inhibitor, although only two callus cell lines show detectable amounts of immunoreactive proteins at the same Mr as dodecandrin. Other immuno-reactive proteins were detected in callus (Mr 31000, 33000, 41000 and 43000) and in suspension cells (Mr 23000 and ∼43000), and may be ribosome inhibitors related to dodecandrin—either other RIPs or dodecandrin at various stages of processing.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Springer
    Journal of chemical ecology 18 (1992), S. 1541-1549 
    ISSN: 1573-1561
    Schlagwort(e): Leafy spurge ; Euphorbia esula ; small everlasting ; Antennaria microphylla ; hydroquinone ; arbutin ; sucrose ; tissue culture ; biotransformation ; allelopathy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Abstract Euphorbia esula (leafy spurge) suspension culture cell bioassays were used to determine whether sucrose accumulation enhanced the glucosylation (detoxification) of hydroquinone in this noxious weed. The bioassay results indicate that cold temperatures and exogenous hydroquinone represent a dual stress to spurge cell growth that can be partially ameliorated by hydrolysis of sucrose. The persistent susceptibility of leafy spurge suggests that hydroquinone-producing forage plants (which are not toxic to animals) might be used as natural competitors.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 3
    ISSN: 1573-5028
    Schlagwort(e): hygromycin ; inheritance ; maize ; tissue culture ; transformation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Embryogenic maize (Zea mays L.) callus cultures were transformed by microprojectile bombardment with a chimeric hygromycin phosphotransferase (HPT) gene and three transformed lines were obtained by selecting for hygromycin resistance. All lines contained one or a few copies of the intact HPT coding sequence. Fertile, transgenic plants were regenerated and the transmission of the chimeric gene was demonstrated through two complete generations. One line inherited the gene in the manner expected for a single, dominant locus, whereas two did not.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 4
    Digitale Medien
    Digitale Medien
    Springer
    The journal of membrane biology 130 (1992), S. 105-114 
    ISSN: 1432-1424
    Schlagwort(e): Na+/H+-exchange ; protein kinase A ; protein kinase C ; vasopressin ; distal tubule ; tissue culture
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Summary We have analyzed the mechanism of Na+-dependent pHi; recovery from an acid load in A6 cells (an amphibian distal nephron cell line) by using the intracellular pH indicator 2′7′-bis(2-carboxyethyl)5, 6 carboxyfluorescein (BCECF) and single cell microspectrofluorometry. A6 cells were found to express Na+/H+-exchange activity only on the basolateral membrane: Na+/H+-exchange activity follows simple saturation kinetics with an apparent K mfor Na+ of approximately 11 mm; it is inhibited in a competitive manner by ethylisopropylamiloride (EIPA). This Na+/H+-exchange activity is inhibited by pharmacological activation of protein kinase A (PKA) as well as of protein kinase C (PKC). Addition of arginine vasopressin (AVP) either at low (subnanomolar) or at high (micromolar) concentrations inhibits Na+/H+-exchange activity; AVP stimulates IP3 production at low concentrations, whereas much higher concentrations are required to stimualte cAMP formation. These findings suggest that in A6 cells (i) Na+/H+-exchange is located in the basolateral membrane and (ii) PKC activation (heralded by IP3 turnover) is likely to be the mediator of AVP action at low AVP concentrations.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 5
    ISSN: 1432-2242
    Schlagwort(e): Lolium perenne ; Mitochondrial genome ; atp6 ; coxI ; tissue culture
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Lolium perenne L. male-sterile and fertile cytoplasms contain different mitochondrial genomes, as revealed by Southern hybridization with a number of heterologous mitochondrial probes. In addition, transcriptional patterns of atp6 and coxI genes distinguish both cytoplasmic types. The majority of the L. perenne sequences from male-sterile and fertile cytoplasm showing homology with these two genes has been cloned and mapped by restriction digestion. A complex genomic organization, especially concerning coxI homologous sequences, was found in the male-sterile cytoplasm. Furthermore, during the course of these studies tissue-culture-induced mtDNA mutations in a number of coxI-containing sequences were detected in regenerated plants.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 6
    Digitale Medien
    Digitale Medien
    Springer
    Plant cell, tissue and organ culture 31 (1992), S. 155-159 
    ISSN: 1573-5044
    Schlagwort(e): cactus ; micropropagation ; tissue culture
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Yellow pitaya (Mediocactus coccineus) seeds were sown on Murashige and Skoog (1962) mineral salt medium. After germination, epicotyls were placed on media enriched with a combination of naphthaleneacetic acid (NAA) (0.05, 0.27 or 0.54 μM) and benzyladenine (BA) (2.2 or 4.4 μM). The apical tip was excised from half of the shoots and the other half were kept intact. Different values for proliferation rate, shoot length and thickness were observed on each medium. The cotyledons and roots were placed on MS medium supplemented with NAA (2.7 or 5.4 μM) and embryogenic calluses were formed. Somatic embryos were induced on these media and then they normally developed on a growth regulator-free medium.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 7
    ISSN: 1573-5044
    Schlagwort(e): Agrobacterium transformation ; Cucumis sativus ; gene transfer ; neomycin phosphotransferase ; tissue culture
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Cucumber (Cucumis sativus L.) petiole and leaf segments of two pickling genotypes were transformed with Agrobacterium tumefaciens strain LBA 4404, an octopine Ti-plasmid deletion mutant that is avirulent (disarmed plasmid), but to which were added T-DNA inserts on binary plasmids (pBIN 19, ca. 10 kb, and pCGN 783, ca. 25 kb). Expression of neomycin phosphotransferase (NPT II) encoding resistance to the aminoglycoside kanamycin was used as a selectable marker. Factors which influenced the frequency of callus development on medium containing kanamycin (75 mg l-1) were explant size, bacterial concentration and length of exposure, cocultivation period, and presence of acetosyringone. The optimal procedure involved exposing segments of petiole (4–6 mm) or leaf (0.5 cm2) segments to a bacterial suspension (108 cells ml-1) containing 20 μM acetosyringone for 5 min, followed by a 48 h cocultivation period on a tobacco feeder layer. Explants were placed on MS medium containing 500 mg l-1 carbenicillin, 75 mg l-1 kanamycin, and NAA/BA (5.0/2.5 μM) or 2,4-d/BA (5.0/5.0 μM) and subcultured twice, each after a 2–3 week period, onto fresh media. The overall frequency of transformed callus was 20–50%; the frequency of plantlet regeneration from transformed callus was 8–15%. Twenty-one out of 23 individual plants recovered from two genotypes of pickling cucumber were NPT II positive (transformation frequency of 9%). Copy number of the NPT II gene insert (35S-NPT II-3′ fragment, ca. 2.2 kb) in three transformed plants was estimated at ten per haploid genome, indicative of multiple insertions within the cucumber genome. Multimers of the gene (visible as 4.4 and 6.6 kb fragments in Southern analysis) were detected in one plant, suggestive of tandem duplications or repeats. Progeny from a cross between this transformed plant and a nontransformed control showed segregation for the NPT II gene in dot-blot assays; at least 24 plants out of 32 were kanamycin positive. Copy number in the progeny was variable, and ranged from none to ten.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 8
    ISSN: 1573-5044
    Schlagwort(e): carbohydrate ; germination ; Impatiens L. ; Impatiens platypetala L. ; nitrogen ; tissue culture
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract In vitro germination of 20-day old immature ovules of Impatiens platypetala Lindl. was inhibited at concentrations as low as 50 mM sucrose or mannitol and 100 mM glucose. Younger ovules (12, 14, and 16 days old) were similarly inhibited at 100 mM sucrose. Inorganic nitrogen concentration did not affect germination regardless of ovule age, but seedling fresh weight was significantly less and abnormal development of seedlings was significantly increased by total inorganic nitrogen concentrations higher or lower than 30 mM (at a ratio of 20: 10 mM NO3 -: NH4 +) in the culture medium.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 9
    Digitale Medien
    Digitale Medien
    Springer
    Plant cell, tissue and organ culture 28 (1992), S. 249-254 
    ISSN: 1573-5044
    Schlagwort(e): callus ; Gomphrena officinalis ; medicinal plant ; plant regeneration ; tissue culture
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Leaf and stem segments of Gomphrena officinalis originated from aseptically grown seedlings were used to initiate cultures. Callus production was obtained on gelled Murashige & Skoog medium supplemented with 6-benzylaminopurine alone (1.0, 5.0 or 10.0 mgl-1) or combined with α-naphthalene acetic acid (0.1, 0.5 and 1.0 mgl-1) after 10 to 15 days of culture, and can be transferred to fresh medium every 30 days. The combinations of 5.0 or 10.0 mgl-1 of 6-benzylaminopurine with 0.1 mgl-1 of α-naphthalene acetic acid were found to be the best for shoot regeneration. Adventitious shoot formation occurred after 50 to 60 days of culture in leaf and internode stem explants. Nodal segments developed actively growing lateral buds after 30 days of culture. Gelled Murashige & Skoog medium containing 10 mgl-1 of indole-3-butyric acid was considered optimal for the rooting of shoots. Rooted plants transferred to potting soil could be successfully established.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 10
    Digitale Medien
    Digitale Medien
    Springer
    Plant cell, tissue and organ culture 28 (1992), S. 281-288 
    ISSN: 1573-5044
    Schlagwort(e): axillary shoot ; growth regulators ; plant regeneration ; tissue culture
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract We succeeded in cultivating onion plants in vitro with a high potential for shoot regeneration. The apex must be destroyed or injured to obtain axillary buds. This capacity was restricted to the abaxial base of the youngest sheaths. It was shown necessary to restore plant individuality before further proliferation; this process constituted one cycle. For successive regeneration each cycle was composed of three steps: shoot proliferation in the presence of a cytokinin, shoot individualization and plant development in the absence of growth regulators. Effect of growth regulators on the physiological status of onion plants cultured in vitro is discussed.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 11
    ISSN: 1573-5060
    Schlagwort(e): Brassica oleracea ; bud stage ; embryogenesis ; genetic variation ; haploidy ; microspore culture ; regeneration ; tissue culture
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary Microspore culture was shown to be applicable to a broad range of accessions belonging to six horticulturally important crop types of Brassica oleracea: broccoli, white cabbage, cauliflower, savoy cabbage, Brussels sprouts and curly kale. Of 64 accessions tested 86% were responsive. Large genotypic differences were found in number of embryos produced per flower bud, and in frequency and mode of regeneration of plants from embryos. B. oleracea was characterized by a strong asynchrony of microspore development within single buds. Microspore populations optimal for culture contained a large proportion (10–40%) of binucleate pollen. An initial high temperature treatment was essential for microspore embryogenesis. Growth conditions of the donor plants during inflorescence formation were less critical.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 12
    Digitale Medien
    Digitale Medien
    Springer
    Euphytica 64 (1992), S. 81-89 
    ISSN: 1573-5060
    Schlagwort(e): interspecific hybrid ; somaclonal variation ; Zinnia
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary Adventitious shoots of Zinnia marylandica, an amphidiploid with limited genetic segregation, were regenerated from cotyledonary tissue on Murashige-Skoog (MS) media containing 0.2 or 22.2 μM thidiazuron (TDZ) and grown through flowering. Fisher's Test for Equal Variance indicated tissue culture induced plants had more variation than seed-derived control plants. Twelve of 149 (8%) plants derived from 0.2 μM TDZ and three of 23 (13%) plants from 22.2 μM TDZ had variant characters. Aberrant characteristics in self-pollinated variants included plant height, fertility, flower color and morphology, and were sexually transmitted, indicating genetic change had occurred. Aberrant characteristics not observed in regenerated plants arose in progeny.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 13
    ISSN: 1573-5036
    Schlagwort(e): biomass partitioning ; nutrient uptake ; plant adaptation ; soil acidity ; somaclonal variation ; Stylosanthes guianensis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract Somaclonal variation offers the possibility to obtain changes in one or a few characters of an otherwise outstanding cultivar without altering the remaining, and often unique, part of the genotype. It has been shown to be heritable for some species. A check line of Stylosanthes guianensis (Aubl.) Sw., CIAT 2243 and 14 somaclones in the R4 generation, selected after three generations from the original 114 plants regenerated from callus cultures, were used in a glasshouse trial. The main objective of the study was to evaluate the physiological basis of the differences in agronomic performance of certain somaclones over the check genotype when grown in a sandy loam acid soil at low or high fertility level. Measurements at the time of harvest (170 days of plant age) included dry matter distribution between shoot and roots, leaf area production, nutrient levels in soil and plant parts, and uptake of nutrients from soil. Somaclones differed with the check genotype in terms of (i) partitioning of fixed carbon between the shoot and roots; (ii) root biomass production and (iii) uptake of nitrogen and phosphorus. Positive relationships were found between total nitrogen uptake and total biomass, and total phosphorus uptake and total biomass, and total phosphorus uptake and total nitrogen uptake. The results of this study provide an insight into the potential use of somaclonal variation for the improvement of plant adaptation to acid soil conditions.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 14
    Digitale Medien
    Digitale Medien
    Springer
    Plant cell, tissue and organ culture 28 (1992), S. 45-51 
    ISSN: 1573-5044
    Schlagwort(e): chickpea ; Cicer arietinum L. ; tissue culture ; regeneration
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract For the purpose of developing an in vitro regeneration system for chickpea (Cicer arietinum L.), an important food legume, immature cotyledons approximately 5 mm long were excised from developing embryos and cultured on B5 basal medium supplemented with 1.5% sucrose and various growth regulator combinations. Only non-morphogenic callus was formed in response to concentrations of 2,4-dichlorophenoxyacetic acid (2,4-D), naphthaleneacetic acid (NAA) and 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) previously reported to induce somatic embryogenesis on immature soybean cotyledons. However, 4.6, 13.7, and 45.6 μM zeatin induced formation of white, cotyledon-like structures (CLS) at the proximal end of immature cotyledons placed with adaxial surface facing the agar medium. No morphogenesis, or occasional formation of fused, deformed CLS, was observed when zeatin was replaced with kinetin or 6-benzyladenine, respectively. The highest response frequency, 64% of explants forming CLS, was induced by 13.7 μM zeatin plus 0.2 μM indole-acetic acid (IAA). Within 20–40 days culture on zeatin, shoots formed at the base of CLS on approximately 50% of CLS-bearing explants, and proliferated upon subsequent transfer to basal medium with 4.4 μM BA or 4.6 μM kinetin. This regeneration system may be useful for genetic transformation of chickpea.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 15
    Digitale Medien
    Digitale Medien
    Springer
    Plant cell, tissue and organ culture 29 (1992), S. 135-138 
    ISSN: 1573-5044
    Schlagwort(e): grain legume ; grass pea ; rooting ; tissue culture
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Protocols have been developed for the in vitro production of plants from callus derived from root explants of Lathyrus sativus cv. P-24. Callus and shoot regeneration were achieved only in MS medium supplemented with 10.7 μM naphthaleneacetic acid and an increased concentration of kinetin (0.9 μM for 14 days to 1.4 μM for 18 days) during callusing. The shoots obtained rooted in 1/2 MS supplemented with 0.5 μM indolebutyric acid. During the year plants have been regenerated several times. The requirement for growth regulators is very specific and narrow.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 16
    Digitale Medien
    Digitale Medien
    Springer
    Plant cell, tissue and organ culture 31 (1992), S. 161-167 
    ISSN: 1573-5044
    Schlagwort(e): tissue culture ; Solanum tuberosum
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The regeneration of plants from leaf explants of a number of potato cultivars using a number of published one-, two- and three-step methods was assessed. A method using a pretreatment with high levels of auxin and cytokinin coupled with silver thiosulphate in the regeneration medium proved the most rapid and efficient for the eight cultivars examined.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 17
    Digitale Medien
    Digitale Medien
    Springer
    Plant cell, tissue and organ culture 31 (1992), S. 245-247 
    ISSN: 1573-5044
    Schlagwort(e): micropropagation ; organogenesis ; plant regeneration ; tissue culture
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 18
    Digitale Medien
    Digitale Medien
    Springer
    Methods in cell science 14 (1992), S. 113-117 
    ISSN: 1573-0603
    Schlagwort(e): tissue culture ; monocyte-macrophages ; Plastek-C ; polystyrene ; cell growth
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Many investigators have found that the surface on which cells are cultured can be an important factor in their adherence and subsequent growth. To enhance the development of monocyte-macrophage cultures, we have grown these cells on polystyrene tissue cultureware that has been treated with gas plasma to induce a positively charged culture surface (Plastek-C cultureware from Tekmat). Human monocyte-macrophages grown on Plastek-C tissue cultureware demonstrated a greater cell protein content during culture development as compared to monocyte-macrophages grown on standard polystyrene tissue cultureware. Part of the reason for enhanced development of human monocyte-macrophage cultures on Plastek-C cultureware seemed to be due to a higher density of cells maintained during the initial stages of culture development.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 19
    Digitale Medien
    Digitale Medien
    Springer
    Plant cell, tissue and organ culture 31 (1992), S. 249-252 
    ISSN: 1573-5044
    Schlagwort(e): organogenesis ; tissue culture
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 20
    Digitale Medien
    Digitale Medien
    Springer
    Plant cell, tissue and organ culture 28 (1992), S. 125-128 
    ISSN: 1573-5044
    Schlagwort(e): organogenesis ; Ranunculus asiaticus ; tissue culture
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Different plant explants of Persian buttercup (Ranunculus asiaticus L.) were screened for callus induction and adventitious shoot regeneration on different media to establish totipotent cultures. Murashige & Skoog (MS) medium was used, supplemented with different concentrations of the following growth regulators: kinetin, benzyladenine (BA), naphthaleneacetic acid (NAA) and indoleacetic acid (IAA). Callus was induced and adventitious buds regenerated only from cotyledonary explants after 4–5 weeks. Subculture of the regenerated buds on the same basal medium in presence of gibberellic acid (GA3) and BA produced well-organized shoots. Rooting was obtained by transferring shoots to growth regulator-free MS medium. A high rate of shoot multiplication has been achieved on medium with high concentration of kinetin and long-day photoperiod. Finally the plants were successfully transferred to soil and grown in a greenhouse.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 21
    Digitale Medien
    Digitale Medien
    Springer
    Plant cell, tissue and organ culture 28 (1992), S. 183-186 
    ISSN: 1573-5044
    Schlagwort(e): cytokinin metabolism ; tissue culture ; BA uptake
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Shoots of a range of species were cultured in vitro on a medium containing 2.22 μM benzyladenine (BA). After 25 days in culture the amount of BA taken up differed between species. The conjugates of BA present in the plant tissues were identified by HPLC. The pattern of BA metabolism varied considerably between species as did the actual levels of each conjugate. Benzyladenine accumulated in Hippeastrum, Alstroemeria and Ficus with little conjugation. In Musa, Rhododendron and Fuchsia BA also accumulated along with its ribosyl and glucoside conjugates. In contrast, very low levels of BA were detected in Gerbera and Dendranthema, but various glucosides did accumulate.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 22
    Digitale Medien
    Digitale Medien
    Springer
    Plant cell, tissue and organ culture 28 (1992), S. 245-248 
    ISSN: 1573-5044
    Schlagwort(e): light ; Prunus cerasifera ; sucrose ; tissue culture
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Trials were carried out to test if the higher growth response shown by shoot clusters of Mr. S. 2/5, a clonal selection of Prunus cerasifera, submitted to short and frequent light-dark regimes could be related to the amount of sucrose added to growth medium. The reduction of sucrose from 30 gl-1 (control) to 22.5 gl-1, 15 gl-1 and 7.5 gl-1 caused a progressive and remarkable inhibition of shoot tip growth. With 15 gl-1 the value of some growth parameters was reduced by more than half. Under 16-h daylength, the best sucrose concentration was 30 gl-1, while with 4-h light-2-h dark no statistical differences appeared between 30 gl-1 and 22.5 gl-1 sucrose. Compared to 16-h light-8-h dark, the 4-h light-2-h dark cycle at the three highest sucrose concentrations gave rise to higher values of fresh and dry weight as well as increasing the number of axillary shoots produced. The increment in growth response induced by the shorter light-dark regime decreased with diminishing growth capacity in the cultures when sucrose concentration was lowered, but it was still appreciable even with 7.5 gl-1. Since the 4-h light-2-h dark cycle induced a favourable effect in culture growth with all sucrose concentrations, we conclude that the greater growth response observed with this light regime was not triggered by carbohydrate availability but by some other unknown factors.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 23
    Digitale Medien
    Digitale Medien
    Springer
    Euphytica 60 (1992), S. 221-228 
    ISSN: 1573-5060
    Schlagwort(e): agronomic performance ; somaclonal variation ; tissue culture ; Triticum aestivum ; wheat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary Seed progeny of tissue culture regenerants of a spring wheat (Triticum aestivum L. cv. HY320) was evaluated for key agronomic traits for three years under field conditions. Initially, 27 regenerant families were tested in hill plots. Among-family and within-family variation was generally highly significant (p 〈 0.01) and nonsignificant, respectively. The variation observed among regenerants on the basis of hill plot testing was not duplicated in subsequent four-row plot experiments. On average, regenerant families yielded 28 and 5% less than the control in dryland and irrigated tests, respectively. Low yielding regenerants tended to produce fewer, lighter kernels per spike. Higher grain protein levels among regenerants were associated with low yields (r=0.85). This study demonstrated that putative somaclonal variation arising from tissue culture failed to produce genotypes agronomically superior to the parental cultivar, HY 320.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 24
    Digitale Medien
    Digitale Medien
    Springer
    Euphytica 62 (1992), S. 145-153 
    ISSN: 1573-5060
    Schlagwort(e): Brassicaceae ; embryo rescue ; interspecific hybrids ; pollination ; risk assessment ; transgenic rapeseed
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary The risk for a gene dispersal is reported for reciprocal crosses between a transgenic rapeseed variety resistant to the herbicide phosphinotricin and five related species. The first stages after pollination were cytologically observed and fertilized ovaries were established in in vitro culture for the production of interspecific hybrids. A similar classification was observed for the index of pollination compatibility and embryo yield. From the 243 embryos produced, 109 plantlets were obtained in a greenhouse. All the interspecific combinations tested were able to produce hybrid plants. A higher number of hybrids was obtained when rapeseed was used as the female parent. The hybrids had the expected triploid structure except for two amphidiploid, B. napus × B. oleracea, and one amphidiploid, B. napus × S. arvensis, plants with 56 chromosomes. The triploid hybrids were sterile or partially fertile but two of the amphidiploid plants, B. napus × B. oleracea, were fully fertile. The cytoplasm source did not seem to affect the fertility of the hybrids.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 25
    Digitale Medien
    Digitale Medien
    Springer
    Euphytica 66 (1992), S. 145-149 
    ISSN: 1573-5060
    Schlagwort(e): beet ; maize ; potato ; oilseed rape ; risk assessment ; transgenic plants
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary The proposed introduction of genetically modified organisms into the environment has caused public and scientific concern. In response to this concern governments have set up biosafety regulations. In this paper a step-by-step scheme is described by which the safety of genetically modified organisms can be assessed. The first step is to determine the level of safety concern for the unmodified organism. Important aspects of the safety concern of the unmodified organism are the potential to hybridize with the wild flora and the ability of the crop to run wild. These aspects have been investigated by a desk study for four agricultural crops (potato, beet, oilseed rape and maize). Maize and potato are genetically isolated from the wild flora. Beet and oilseed rape on the contrary can potentially hybridize with wild relatives in the Netherlands. The risk assessment of the latter two species should focus entirely on the effects of the introduced genetic material.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 26
    Digitale Medien
    Digitale Medien
    Springer
    Plant cell, tissue and organ culture 28 (1992), S. 19-25 
    ISSN: 1573-5044
    Schlagwort(e): immature cotyledons ; Lupinus species ; somatic embryogenesis ; tissue culture
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Somatic embryos were obtained from immature cotyledons of Lupinus angustifolius, L. albus and L. mutabilis but not from L. luteus. Different kinds of basal media and plant growth regulators in primary and secondary culture were tested. The best induction media were based on B5 and were supplemented with 5 mg I-1 2,4-D alone or with 0.25 mg I-1 kinetin. Mature stage somatic embryos were obtained on media containing ABA (0.1–0.5 mg I-1) and a high NH4/NO3 ratio. Embryo germination and plantlet development occurred on MS media supplemented with glutamine or GA3.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 27
    Digitale Medien
    Digitale Medien
    Springer
    Plant cell, tissue and organ culture 28 (1992), S. 187-194 
    ISSN: 1573-5044
    Schlagwort(e): coconut milk ; Cyclamen persicum ; ornamental plant ; regeneration ; somatic embryogenesis ; tissue culture
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Somatic embryos of Cyclamen persicum Mill. could be produced through a callus phase from juvenile explant material including anthers, ovaries and zygotic embryos. The auxin 2,4-D (1.0–1.5 mg l-1) and coconut milk (10% v/v) in MS medium were important factors for the induction of somatic embryogenesis. Somatic embryos germinated into plantlets in MS medium without growth regulators. The plants grew well in the greenhouse and flowered normally. The plants were phenotypically identical to the mother plants with a few exceptions.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 28
    Digitale Medien
    Digitale Medien
    Springer
    Plant cell, tissue and organ culture 28 (1992), S. 207-213 
    ISSN: 1573-5044
    Schlagwort(e): anthracnose ; disease resistance ; Medicago sativa ; somaclonal variation ; tissue culture
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Alfalfa plants were regenerated from callus cultures of three source plants that differed in resistance to anthracnose, caused by Colletotrichum trifolii. All regenerant plants were evaluated for variation in resistance to disease caused by races 1 and 2 of the pathogen. Of eighty-two plants that were regenerated and evaluated, no plants responded differently to inoculation with race 1 of C. trifolii, but two plants (2.4%) differed in resistance when inoculated with race 2. The source plant of these regenerants was resistant to races 1 and 2 of the pathogen but the regenerants were resistant to race 1 and susceptible to race 2. No variants to race 1 were detected. The susceptible response of the variant plants to race 2 was confirmed by cytological analysis and was consistent with the response of nonregenerant susceptible plants. These plants represent a near-isogenic plant model for studying the molecular biology of resistance and susceptibility to anthracnose of alfalfa.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 29
    Digitale Medien
    Digitale Medien
    Springer
    Plant cell, tissue and organ culture 28 (1992), S. 229-230 
    ISSN: 1573-5044
    Schlagwort(e): clonal propagation ; multiple shoots ; tissue culture
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 30
    Digitale Medien
    Digitale Medien
    Springer
    Plant cell, tissue and organ culture 31 (1992), S. 195-201 
    ISSN: 1573-5044
    Schlagwort(e): Beta vulgaris ; morphogenesis ; regeneration ; tissue culture
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract In preparation for gene transfer experiments we investigated factors that might affect the production of shoots and somatic embryos from the wound callus of cultured sugarbeet leaf discs. A complex interaction was found between the leaf disc plating density, the disc culture medium, the source-shoot culture medium and the frequency of disc transfer to fresh medium. The most productive protocol utilized: source shoots maintained on MS medium containing 0.25 mg 1-1 BA; multiple leaf discs (ten 4-mm discs/plate) plated onto an enriched modification of MS medium (RV) containing 1.0 mg 1-1 BA and solidified with 0.3% Gelrite (not permitted to dry during hardening); and transfer of the discs to fresh medium every two weeks during the first month. This standard protocol produced more callus per plate and higher rates of morphogenesis per unit dry weight of callus than did the one-step method of Saunders and Doley. Water availability considerations were found to be critical to obtaining high morphogenic rates. Root induction frequency and quality was superior on shoots transplanted to MS medium containing 1 mg 1-1 NAA as the sole growth regulator compared to IAA at the same concentration.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 31
    Digitale Medien
    Digitale Medien
    Springer
    Euphytica 64 (1992), S. 1-10 
    ISSN: 1573-5060
    Schlagwort(e): tissue culture ; somaclonal variation ; plant breeding ; Triticum aestivum ; mutation ; wheat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary Plants were regenerated from immature embryo cultures of 35 winter wheat genotypes. A total of 7142 R2 spike lines from 1593 R1 plants were assessed in the field for somaclonal variants of morphological traits in 1985/86, 1986/87 and 1987/88. Selected variants were studied for their possible genetic basis. Populations of R1 plants were highly variable due mainly to the physiological disturbances resulting from the in vitro processes. Overall somaclonal variation frequencies were 14.2% on the R1 plant basis and 5.3% on the R2 spike basis. Spectra of the variants were similar in the different R2 populations with predominant variants being altered negatively in plant height, maturity, awnedness, and spike and plant types. Over 90% of the variants were observed in some spike progenies of individual regenerants, while the others appeared in all spike progenies of the regenerants and in progenies of different regenerants derived from the same explant embryos. Both uniform R2 variant families and spike lines were found in addition to the segregating variants, which constituted the majority. On average, in a variant family and line, 18 and 14% of their component lines and plants varied, respectively. Inheritability was demonstrated for the variations in both segregated and uniform variant families and spike lines. Of 134 variant selections tested, about 70% was classified inhernable. Both recessive and dominant gene mutations at one, two or three loci were evident in some of the variants as suggested by segregation data.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 32
    Digitale Medien
    Digitale Medien
    Springer
    Plant cell, tissue and organ culture 29 (1992), S. 37-42 
    ISSN: 1573-5044
    Schlagwort(e): mutagenesis ; petal culture ; regeneration ; somaclonal variation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract To obtain carnation variants differing from those produced by organogenesis alone, in vitro petal cultures were subjected to gamma irradiation. Histological analysis revealed the surface origin of buds and the different steps in meristem formation. A dose of 40 Gy administered on the fourth day of culture produced variants of horticultural interest in ‘Niky’. This period corresponded to dedifferentiation of cells that subsequently developed into bubs.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 33
    Digitale Medien
    Digitale Medien
    Springer
    Plant cell, tissue and organ culture 29 (1992), S. 145-151 
    ISSN: 1573-5044
    Schlagwort(e): aggressiveness ; disease resistance ; Saccharum sp. ; tissue culture ; Xanthomonas campestris pv. vasculorum
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Sugarcane plantlets were sectioned halfway between the base and the youngest ligule and then inoculated by soaking the wound in a suspension of Xanthomonas campestris pv. vasculorum. The infection caused rapid necrosis of the inoculated leaves, chlorosis of uninoculated leaves, or death of the inoculated plantlet. New tillers sometimes showed chlorosis or white streaks. The effects of the inoculum concentration, the cultivar, and the bacterial strain on symptom severity were determined. The ranking of cultivars depended on the inoculum concentration, and strains were found to differ with regard to aggressiveness. However, cultivars and strains were more effectively classified in greenhouse trials. The poor expression of leaf resistance appeared to limit the use of the in vitro test.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 34
    Digitale Medien
    Digitale Medien
    Springer
    Plant cell, tissue and organ culture 29 (1992), S. 173-178 
    ISSN: 1573-5044
    Schlagwort(e): leguminosae ; Prosopis tamarugo ; regeneration ; tissue culture
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Callus cultures of Prosopis tamarugo Phil (Leguminosae, Sub family-Mimosoideae) were established from hypocotyls and cotyledons on MS medium supplemented with NAA (2.0 mg l-1) and BAP (0.2 mg l-1). Regeneration through various juvenile explants was obtained on hormone-free and high cytokinin containing Murashige and Skoog's medium. Multiple shoot buds formation was observed from the embryonic axis on MS medium incorporated with BAP (5.0 mg l-1)). Elongation of shoot buds was observed on subsequent transfer to MS medium with BAP (1.0–2.5 mg l-1) or without BAP. Explants containing apical meristem showed higher number of shoot formation at an early period. De novo shoot buds formation through callus morphogenesis was observed at the base of differentiated shoots on high cytokinin containing medium. All the manipulations of salt strength of MS, nitrogen, carbon, ascorbic acid and polyamines failed to induce organogenesis in isolated callus. In vitro produced shoots were rooted on MS medium supplemented with IBA or NAA singly or in combination.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 35
    Digitale Medien
    Digitale Medien
    Springer
    Plant cell, tissue and organ culture 29 (1992), S. 179-186 
    ISSN: 1573-5044
    Schlagwort(e): Douglas-fir ; maturation ; micropropagation ; plagiotropism ; rejuvenation ; tissue culture
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Plagiotropic angle of seedling-derived Douglas-fir plantlets varied with position of adventitious bud origin on the explanted cotyledon rosette, being least at its center (18°) and greatest (45°) along the basal third of the cotyledon. When the tops of plagiotropic plantlets (55°) were grafted to seedling rootstock, they assumed a near-vertical orientation (10°), with pectinate changed to radial leaf arrangement, within 5 months. Conversely, seedling tops grafted to plagiotropic plantlet rootstock grew plagiotropically (56°). These, and other observations lead to a hypothesis that plagiotropism in cotyledon-derived plantlets results in part from an incomplete vascular connection of the root system to the shoot. In contrast, the greater plagiotropic angle in plantlets from a 12 year-old tree, decreased by only half (from 72° to 34°) after grafting to seedling rootstock. First-season height increment of these plantlets was only 60 percent of seedling or juvenile plantlet height increment, and was unaffected by rootstock type. The adult-origin plantlets exhibited mature shoot morphology, and unchanged plagiotropism after 2 years growth in large pots. Thus it appears that the culture-induced juvenile appearance and behaviour noted for this material when maintained in vitro, is dependent on the continued presence of the culture conditions.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 36
    Digitale Medien
    Digitale Medien
    Springer
    Plant cell, tissue and organ culture 30 (1992), S. 221-226 
    ISSN: 1573-5044
    Schlagwort(e): electrophysiology ; embryogenesis ; organogenesis ; polarity (cell) ; surface potentials ; tissue culture
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The surface potentials of tobacco and carrot callus have been measured at various stages of differentiation to form shoots or embryoids using non-polarizable silver/silver chloride electrodes in KCl-filled capillaries. Values on de-differentiating media were seldom in excess of 10mV and never exceeded 15 mV. Transfer of tobacco callus to a medium conducive to shoot-formation resulted in the appearance of sharply defined areas of much higher surface potentials corresponding to the positions of developing vascular nodules (meristemoids). Shoot regeneration always occurred at the boundary of the developing meristemoids, suggesting that a very steep potential gradient within the tissue may be an important feature of organogenesis. Similar measurements made on carrot callus regenerating embryoids did not show any corresponding high surface potentials in the regions of embryogenesis. It is concluded that the natural electrical conditions in callus undergoing organogenesis are quite different to those during the formation of embryoids. A possible explanation is proposed.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 37
    Digitale Medien
    Digitale Medien
    Springer
    Plant cell, tissue and organ culture 30 (1992), S. 237-241 
    ISSN: 1573-5044
    Schlagwort(e): plant growth regulators ; shoot regeneration ; tissue culture
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract A protocol for high frequency adventitious shoot regeneration adventitious shoot regeneration from leaf explants of Rhododendron spp. has been developed. The highest percentage of regeneration and the greatest number of shoots were obtained when leaf explants were cultured on Anderson's medium containing 4.9 μM IBA and 73.8 μM 2iP. Genotypic variation was observed for adventitious shoot regeneration potential among the seven cultivars tested. Regeneration frequencies ranged from 0 to 96%. ‘Lodestar’ had the highest rate of regeneration after 3 months of culture with 96% shoot regeneration and an average of 14 shoots per explant. Regenerated shoots were rooted in soil in about 2 months. This protocol should be useful in applying gene transfer techniques to Rhododendron improvement.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 38
    Digitale Medien
    Digitale Medien
    Springer
    Plant cell, tissue and organ culture 31 (1992), S. 179-184 
    ISSN: 1573-5044
    Schlagwort(e): Belladonna lily ; Cape belladonna ; March lily ; micropropagation ; sucrose ; tissue culture ; twin-scales
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Amaryllis belladonna L. plants were multiplied successfully by means of tissue culture techniques. Different plant parts were tested as explant material, but plantlets could only be generated from the twin-scales and immature scapes. These in vitro-formed plantlets were divided into four parts and used for further multiplication. The twin-scale explants had the highest multiplication rate when a medium with 22.2 μM benzyladenine and 0.54 μM naphthaleneacetic acid was used. The sucrose concentration played an important role in the initiation of new plantlets, and the best results were obtained when a sucrose concentration of 2–3% was used. Anatomical observations were made during the initiation of the new plantlets.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 39
    Digitale Medien
    Digitale Medien
    Springer
    Plant cell, tissue and organ culture 29 (1992), S. 187-198 
    ISSN: 1573-5044
    Schlagwort(e): Douglas-fir ; in vitro grafting ; mature ; maturation ; micrpropagation ; rejuvenation ; tissue culture
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract A method was developed for the establishment of shoot cultures from Douglas-fir trees selected for outstanding growth and form in a 12-year-old genetic test. Vegetative buds from the lower crown were sterilized and grafted in vitro onto juvenile clonal rootstock. The rootstocks were produced from adventitious buds induced on cotyledons, and were maintained through micropropagation. Buds that established grafts slowly elongated into shoots, which were harvested and multiplied through micropropagation. Grafts often grew several new shoots which in turn could be harvested. In 1987, 2830 buds were grafted from 18 superior trees. Twenty nine grafts (1%) produced shoots which established 11 of the 18 trees in culture. Their appearance and behavior in vitro became more juvenile over 1–3 years, as indicated by shoot and needle morphology, disappearance of episodic growth pattern, increase in multiplication rates, and ability of needles to produce adventitious buds. The five most prolific of the 11 clones were given a pre-rooting treatment and planted in soil under fog. The success of rooting and subsequent establishment in soil varied from 5 to 17% depending on clone. In contrast, trees multiplied in vitro for 1–2 years longer showed soil establishment rates from 8–60%. This technique allows establishment, multiplication, and maintenance in vitro of cultures from high value Douglas-fir genotypes. Such cultures may serve as a starting point for further research on rejuvenation and cloning.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 40
    Digitale Medien
    Digitale Medien
    Springer
    Plant cell, tissue and organ culture 30 (1992), S. 41-49 
    ISSN: 1573-5044
    Schlagwort(e): Lamiaceae ; Mentha ; organogenesis ; tissue culture
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Leaf disks from peppermint, spearmint, orange mint, lavender mint and Scotch spearmint were cultured on various Murashige-Skoog-based media in order to regenerate shoots. A significantly larger average number of orange mint leaf disks regenerated shoots on basal medium containing 44.4 μM benzyladenine (BA) and 250 ml l-1 coconut water (CW). Shoots regenerated from peppermint leaf disks cultured on basal medium containing 44.4 μM BA and 250 ml or 450 ml l-1 CW. The most shoots regenerated from orange mint leaf disks cultured on medium containing 10 g l-1 washed Difco Bacto-agar. Disks excised from the bases of the first expanding pair of orange mint leaves cultured under dark conditions regenerated a significantly larger average number of shoots. Histological studies suggested that shoots regenerated from the palisade parenchyma cells associated with vascular tissue.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 41
    Digitale Medien
    Digitale Medien
    Springer
    Plant cell, tissue and organ culture 30 (1992), S. 15-29 
    ISSN: 1573-5044
    Schlagwort(e): cell suspension ; embyrogenesis ; Lolium ; regeneration ; somaclonal variation ; statistical analysis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Cell suspension colonies from four embryogenic Lolium temulentum lines were selected and plated individually in 25 embryoid maturation treatments which varied in various factors reported to stimulate embryogenesis or improve regeneration. Using a numerical scoring system to compare the cultures against a control, treatments were identified which increased growth, suppressed morphogenesis or encouraged premature shoot formation. No treatment significantly improved the proportion of colonies with globular or mature embryoids, but some prevented maturation and increased the proportion with translucent embryogenic proliferation. Other treatments accelerated maturation causing increased de-differentiation of embryogenic tissues. These treatments also tended to discourage the differentiation of discreet embryoids. Colonies were later transferred en masse to a regeneration medium and scored using another numerical system. Embryoid maturation conditions were then identified which increased or suppressed subsequent shoot regeneration. The two scoring systems enabled cultures of the four lines to be characterised in detail and identified somatic variation in embryogenic development, morphogenesis and de-differentiation.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 42
    Digitale Medien
    Digitale Medien
    Springer
    Software quality journal 1 (1992), S. 193-208 
    ISSN: 1573-1367
    Schlagwort(e): cost estimation ; cost models ; software development ; metrics ; risk assessment ; project management
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Informatik
    Notizen: Abstract This paper describes a case study in the use of the COCOMO cost estimation model as a tool to provide an independent prognosis and validation of the schedule of a software project at IBM UK Laboratories Ltd, Hursley. Clearly case studies have the danger of being anecdotal however software engineers often work in situations where sufficient historical data is not available to calibrate models to the local environment. It is often necessary for the software engineer to attempt to use such tools on individual projects to justify their further use. This case study describes how we began to use COCOMO and concentrates on some of the problems and benefits which were encountered when trying to use COCOMO in a ‘live’ development environment. The paper begins by discussing some problems in mapping the COCOMO phases on to the IBM development process. The practical aspects of gathering the development parameters of the model are described and the results of the work are presented in comparison to a schedule assessment using other prognosis techniques and the planned schedule at other milestones in the project's history. Some difficulties experienced in interpreting the data output from the model are discussed. This is followed by a brief comparison with other schedule analysis techniques used in quality assurance. We hope this case study shows that despite the problems in trying to use models such as COCOMO there are significant benefits in helping the user understand what is required to use such tools more effectively to improve software development cost estimates in the future.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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