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Cytotoxic potential of melamine was evaluated with the use of two in vitro models i.e. cell cultures of rat hepatoma (line FaO) and rat skeletal muscle (line L6). The cultures were exposed for 24, 48, and 72 h to melamine at eight concentrations, ranged from 0.01 to 10 mM. Four different assays were applied in which various biochemical endpoints were assessed: mitochondrial activity - MTT reduction assay, proliferation - Commassie Brilliant Blue (CBB) dye binding assay, lysosomal activity - neutral red uptake (NRU) assay, and membrane integrity - LDH release assay. Effective concentrations (EC₂₀, EC₅₀, EC₈₀) were calculated from concentration-response curves, and then they were averaged over three independently conducted experiments. It was found that MTT assay was the most sensitive to this compound. After 48 h exposure EC₅₀ values (mM, mean ± SD) for FaO and L6 cells were 6.4 ± 0.62, and 8.2 ± 1.51, respectively. The inhibition of lysosomal activity measured by NRU assay, and damage of plasma membrane measured by LDH assay were detected in L6 (but not in FaO) cells; however, the effects took place after longer (72 h) exposure. At that time EC₅₀ values were 5.2 mM and 9.2 mM for NRU and LDH, respectively. In spite of the low cytotoxicity of melamine, more studies are needed for hazard identification and characterization of the compound.
Isatis concstricta Davis (an endemic plant of Turkey) suffers from low propagation rates under natural conditions and is threatened due to fast unplanned urbanisation. The study compared the effects of variants of BA + NAA on shoot regeneration on leaf and petiole explants excised from one week old in vitro regenerated seedlings. MS medium containing 1 mg L–1 BA + 1 mg L–1 NAA induced maximum proliferation on petiole and leaf explants with 13.33 and 12.75 shoots per explant repectively. However, leaf explant induced shoots were sturdy and healthier compared to petiole explant induced shoots. These shoots were rooted on MS medium containing 0.5 mg L–1 IBA and the plants were acclimatized in peat moss and sand (v/v). They grew to flowering under ex vitro conditions. This system of regeneration is advantageous for conventional propagation and the results will help in establishment of a powerful and meaningful micropropagation system for I. constricta.
For breeding purposes, the number of neo-tetraploids of apple cultivars have been derived by in vitro technique. The first attempts at rooting and acclimatization of tetraploid shoots failed. The aim of the study was to develop an effective method for rooting microcuttings of apple neo-tetraploids. In the first stage of the study, in vitro rooting method was optimized for the shoots of diploid donor cultivars. Shoots were rooted on Murashige and Skoog [1962] (MS) medium with a reduced content of nitrogen, in the presence of auxins alone or in combination (indole-3-butyric acid – IBA, 1-naphthaleneacetic acid – NAA and indole- -3-acetic acid – IAA) with addition of putrescine, arginine or ornithine. The compounds were applied continuously for 25 days (one-step rooting system) or for seven days with subsequent transplanting shoots onto a medium without these compounds (two-step rooting method). Tetraploid microcuttings of the cultivars ‘Free Redstar’, ‘Gala Must’, ‘Pinova’ and ‘Redchief’ were evaluated for rooting on the selected medium considered optimal for their diploid counterparts. The shoots of all diploid apple scion cultivars had low rooting capacity. IBA alone poorly stimulated root formation. Significant improvement of rooting to 60–80% was achieved through the application of auxins, 2.5 µM IBA or 1.3 µM NAA combined with 5 µM IAA and 50 µM putrescine in the two-step rooting system with darkness and increased temperature of 26°C during seven-day induction phase. The replacement of benzyladenine (BA) by meta-Topolin (m-T) in the last multiplication subculture influenced positively shoot acclimatization. Tetraploids had comparable or slightly lower rooting and acclimatization ability compared to their diploid counterparts.
Zbadano aktywność mutagenną wybranych formulacji herbicydów i regulatorów wzrostu oraz ich substancji biologicznie czynnych. Do oceny zastosowano model mutacji mitochondrialnych u Saccharomyces cerevisiae, mutacji barwnikowych u Chlorella vulgaris oraz test mikrojądrowy w komórkach szpiku kostnego myszy.
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