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61.
Effects of kinetin,paclobutrazol and their interactions on the microtuberization of potato stem segments cultured in vitro in the light 总被引:1,自引:0,他引:1
I. Šimko 《Plant Growth Regulation》1993,12(1-2):23-27
Single-nodal cuttings of Solanum tuberosum (four cultivars) and Solanum chacoense were induced to produce in vitro microtubers on Murashige & Skoog (MS) medium supplemented with 8 g l–1 sucrose and various concentrations of kinetin and paclobutrazol. The cultures were kept 10 days in darkness and then transferred to a 14 h daylength with 100 µE m–2 sec–1 light intensity at 21 °C. Kinetin (2.5 mg l–1) had no significant influence on tuber formation. However, its addition together with paclobutrazol (0.001 mg l–1) significantly enhanced tuberization. Paclobutrazol alone stimulated early tuber initiation and inhibited stem growth. Despite some genotype × treatment interactions, all genotypes (from very early to late and wild type) formed the maximum proportion of explants bearing microtubers on the media containing both plant growth regulators. 相似文献
62.
Plot 82 is one of a hundred permanent plots that have been set up in Croatia for the purpose of long-term and continual investigations of ecosystems and their successions. It is located in the area of Karleuine Plase within the Plitvice Lakes National Park. Vegetation on the plot belongs to association Bromo-Plantaginetum mediae. The association develops in mountainous regions of continental Croatia within a wide altitude range, from 180–1300 m a.s.l. on shallow soil over pervious carbonate rocks. The floristic composition and phytocoenological characteristics of the association have been analyzed using the common methods of the phytocoenological school Zürich-Montpellier, on the basis of 17 phytocoenological records. In addition to floristic composition, some site characteristics have been analysed: soil moisture, calcium carbonate, phosphates, pH value, humus, cation exchange capacity and nitrogen mineralization on the site and in the laboratory. The results obtained are comparable with the data presented in the available phytocoenological and ecological literature. 相似文献
63.
Jan Raška Kateřina Chalušová Jan Krajiček Radomír Čabala Zuzana Bosáková Pavel Štys Alice Exnerová 《Journal of evolutionary biology》2023,36(7):1050-1064
Many prey species change their antipredator defence during ontogeny, which may be connected to different potential predators over the life cycle of the prey. To test this hypothesis, we compared reactions of two predator taxa – spiders and birds – to larvae and adults of two invasive true bug species, Oxycarenus hyalinipennis and Oxycarenus lavaterae (Heteroptera: Oxycarenidae) with life-stage-specific chemical defence mechanisms. The reactions to larvae and adults of both true bug species strikingly differed between the two predator taxa. The spiders were deterred by the defences of adult bugs, but the larval defences were ineffective against them. By contrast, birds attacked the larvae considerably less often than the adult bugs. The results indicate a predator-specific ontogenetic change in defence effectiveness of both Oxycarenus species. The change in defence is likely linked to the life-stage-specific composition of secretions in both species: whereas secretions of larvae are dominated by unsaturated aldehydes, secretions of adults are rich in terpenoids, which probably serve dual function of defensive chemicals and pheromones. Our results highlight the variation in defence between different life stages and the importance of testing responses of different types of predators. 相似文献
64.
65.
A. Soteriou M. D. Carr T. A. Frenkiel J. E. McCormick C. J. Bauer D. Šali B. Birdsall J. Feeney 《Journal of biomolecular NMR》1993,3(5):535-546
Summary
13C-based three-dimensional 1H–1H correlation experiments have been used to determine essentially complete 13C and 1H resonance assignments for the amino acid side chains of uniformly 13C/15N labelled L. casei dihydrofolate reductase in a complex with the drug methotrexate. Excellent agreement is observed between these assignments and an earlier set of partial assignments made on the basis of correlating nuclear Overhauser effect and crystal structure data, indicating that the tertiary structure of the enzyme is similar in solution and in the crystal state.To whom correspondence should be addressed. 相似文献
66.
Jitka Štěpánková 《Folia Geobotanica》1996,31(2):251-262
A total of 6 population samples ofMyosotis stenophylla Knaf, a rare species showing great ecological disjunction in its distribution, were examined to clarify the present status of its karyological variation. In order to elucidate relationships between lowland tetraploid populations ofM. stenophylla and diploid and tetraploid montane populations ofM. alpestris F.W. Schmidt, four population samples ofM. alpestris were also examined. The karyotypes of all populations ofM. alpestris s.l. studied were highly asymmetrical and heterogeneous, being composed of metacentric, submetacentric, subtelocentric and satellited acrocentric chromosomes. The karyotype formula for haploid chromosome set was established: n=x=12=6m+2sm+3st+1tSAT. Multivariate analysis based on chromosome length and shape showed significant differences between diploid and tetraploid forms ofM. alpestris s.l. Four numerical parameters, used to characterize the karyotype ofM. stenophylla, revealed significant differences between populations on serpentine and on non-serpentine substrates. In addition, the noticeable affinity of the karyotype of non-serpentine populations to that ofM. alpestris tetraploids has been shown by means of discriminant analysis. These data suggest that the unique features of serpentine play an important role in the origin of karyotypic differentiation within populations ofM. stenophylla. 相似文献
67.
Six strains ofYarrowia lipolytica tested here were resistant to 10–20 g erythromycin or chloramphenicol per L glycerol-agar medium. Cells tolerating 4 g chloramphenicol per L were very rare and reverted rapidly to the highest resistance. In analogy with EryR mutants ofKluyveromyces lactis, our strains did not grow at 36°C but did not lose their viability at that temperature. Two levels of resistance were found with oligomycin and antimycin A,i.e. 10 and 3 mg/L in the former and 10 and 2 mg/L in the latter. The higher resistance levels segregated mitotically and were, therefore, controlled extrachromosomally. The lower resistance levels showed very frequent changes from sensitivity to resistance that prevented the genetic analysis of this resistance. An almost continuous range of tolerance to <5–400 μg mucidin per L was found in populations of the strains analyzed. Newly formed MucR cells were established only in the presence of the antibiotic. Pure cultures of MucR cells showed an extremely high instability caused by their lower viability and very low growth rate in the absence of mucidin. No loss of resistance to antimycin A was found, although AntR cells revealed similar negative selection. Mutability MucS»MucR and MucR»MucS was higher in AntR cells than in AntS ones. 相似文献
68.
69.
Mouse hybridoma cells cultured on the verge of starvation-induced apoptosis, i.e. in a medium diluted with saline, proved to serve as a sensitive screening system for apoptosis-suppressing activity of nutrient medium components. Conventional amino acid mixtures were found to suppress the starvation-induced apoptosis, whereas a vitamin mixture was ineffective. (Frank F (1995) Biotechnol. Bioeng. 45: 86–90). Recent experiments showed that suppression of apoptosis, and concurrent resumption of growth, could be achieved by addition of single substances at millimolar concentrations. The set of active substances included certain coded L-amino acids (glycine, alanine, serine, threonine, proline, asparagine, glutamine, histidine), non-coded amino acids (-alanine, taurine, 4-aminobutyric acid), and a non-metabolizable analogue (2-aminoisobutyric acid). This finding shows that some amino acids do not act solely as nutrients, but also as specific signal molecules. The specificity of the effect points to the involvement of adaptively regulated amino acid transport systems A and N in maintaining the balance between triggering and suppression of starvation-induced apoptosis. 相似文献
70.
D. Vandák M. Tomáška J. Zigová E. Šturdík 《World journal of microbiology & biotechnology》1995,11(3):363-363
Improved production of butyrate (up to 19 g/l) from whey by Clostridium butyricum was achieved by adding either yeast extract (5 g/l) or biotin (50 g/l). Hydrolysed lactose and proteolysed whey were less effective even with added biotin.The authors are with the Department of Biochemical Technology, Faculty of Chemical Technology, Slovak Technical University, Radlinského 9, Bratislava 812 37, Slovakia 相似文献