In vitro culture of sugarcane infected with maize streak virus (MSV)

Young buds and leaf tissues of sugarcane cv. R 574 (a Saccharum hybrid), healthy or infected with Maize Streak Virus (MSV) were cultured in vitro. The success rate of the cultures from infected material is lower than that from healthy material. The symptoms of the disease were displayed on most of the plantlets produced from buds but only on 6% of the plantlets regenerated from calli. The indirect double-antibody sandwich ELISA technique using a monoclonal antibody makes it possible to identify virus-infected plantlets. In vitro, the infection results in the reduced growth of shoots.     

In vitro degradation of a polymeric dye (Poly R-478) by manganese peroxidase

The aim of this study is the evaluation of the enzymatic action of the ligninolytic enzyme manganese peroxidase (MnP), through a suitable addition of H(2)O(2), as a feasible system for the in vitro degradation of complex structures. For this purpose, a highly recalcitrant polymeric dye (Poly R-478) was selected as a model compound. An amperometric technique was used to determine the H(2)O(2) requirement in the decolorization by nonpurified MnP. Two H(2)O(2) supply strategies-fed-batch (every hour) or semicontinuous (every 5 min)-were applied. The addition of H(2)O(2) in pulses led to a limited decolorization after the pulses and the instantaneous consumption or decomposition of H(2)O(2). Therefore, this way of addition may limit the actual H(2)O(2) concentration in the reaction mixture. In contrast, the semicontinuous strategy maintained lower and prolonged concentrations of H(2)O(2), which allowed a clearly greater decolorization (48% after 2 h). In addition, the effect of Mn(+2) concentration on the decolorization efficiency was investigated to establish the optimal application of the MnP-oxidative system. The enzymatic treatment provoked not only the destruction of the chromophoric groups but also a noticeable breakdown of the chemical structure of the dye. In experiments with pure enzyme, MnP proved to be the main factor responsible for the dye decolorization.     

In vitro regeneration of Minthostachys andina (brett) Epling - a Bolivian native species with aromatic and medicinal properties

Various explants of Minthostachys andina (Brett.) were evaluated for their morphogenic potential under in vitro culture conditions. Axillary buds derived from 2 year-old plants grown in MS-medium supplemented with 4.4 or 8.8 μM BA and 0.054 μM NAA, initiated shoot growth and new shoot formation. Under subculture in NN medium, shoots were rooted in the presence of NAA (1.6, 2.7 or 5.3 μM) alone or in combination with IBA (9.8 μM), and the regenerated plantlets were later acclimatised in the greenhouse. Also, polynodal segments from seedlings initiated multiple shoots and plantlets when initially cultured in presence of NN-liquid salt medium supplemented with 2.2-17.7 μM BA or 4.5-13.6 M TDZ in combination with different auxin-like growth regulators and after a final transfer for root initiation. The same types of responses were found in hypocotyl and leaf explants, which produced adventitious shoots in the presence of TDZ. The use of antioxidants helped to prevent browning and favoured organogenesis. This revised version was published online in June 2006 with corrections to the Cover Date.     

In vitro bulb development in shallot (Allium cepa L. Aggregatum Group): effects of anti-gibberellins,sucrose and light

Bulbing was studied in shallot plants cultured in vitro. Bulbing occurred under a 16 h photoperiod with fluorescent + incandescent light and 30-50 g 1(-1) sucrose in the culture medium. Exogenous gibberellin (10 microM GA3) inhibited leaf and root growth and bulbing. When added to the medium at a concentration of 10 microM, three inhibitors of gibberellin biosynthesis (ancymidol, flurprimidol and paclobutrazol) promoted bulb formation and the percentage of bulbing. When ancymidol was used in combination with GA3, it did not reverse the effect of GA3 applied alone. Under treatments with 30-70 g l(-1) sucrose, bulbing ratios greater than those found in control plants were achieved by addition of ancymidol, and bulb fresh weight was increased in the same way. Ancymidol caused a 66% decrease in sucrose content in leaf bases but greatly increased the glucose, fructose and fructan contents. The increase in fructan content by ancymidol could result from the three-fold rise in total [14C]sucrose uptake per plant from the culture medium associated with a marked increase in leaf base labelling at the expense of root labelling. The possible role of ancymidol is discussed and evidence supports a major regulatory role for gibberellins in bulbing.     

In vitro evaluation of six fungicides on radial mycelial growth and regrowth of Fusarium pallidoroseum isolated from castor (Ricinus communis) in Samaru,Nigeria

Six fungicides at three rates (1.5x, 1.0x and 0.5x mg a.i/ml) were evaluated on radial growth and and regrowth of mycelia of Fusarium pallidoroseum isolated from castor (Ricinus communis) in vitro. It was observed that the fungicides (Benomyl, Benomyl + Thiram, Mancozeb, Metalaxyl-m + Thiomethoxan + Difenconazol, Tricyclazole and Carbendazim + Mancozeb) at all the concentrations tested inhibited mycelial growth and regrowth of the fungus. Benomyl, Benomyl + Thiram and Tricyclazole completely inhibited mycelia growth of fungus at 1.5x, 1.0x and 0.5x mg a.i/ml. Metalaxyl-m + Thiomethoxan + Difenconazole, Carbendazim + Mancozeb partially inhibited radial growth and re-growth of mycelia only at 1.5x mg a.i/ml, not at 1.0x and 0.5x mg a.i/ml. The inhibitory effect of all the fungicides on mycelia growth and re-growth was greatest at 1.x5 mg a.i/ml.     

高压脉冲电场法提取干松针总黄酮及其体外抗氧化性检测

主要研究了高压脉冲电场法提取干松针总黄酮的工艺条件,并对松针总黄酮体外抗氧化性能进行初步分析.结果表明,最优的高压脉冲电场提取条件为:电场强度20 kV/cm,脉冲数8个,料液比1:50.松针总黄酮提取率的影响因素:料液比＞电场强度＞脉冲数.松针落叶中总黄酮物质对自由基清除能力随浓度的增加而升高,松针总黄酮对Fe~(3+)的还原能力比抗坏血酸强.     

Synthesis, characterization, interaction with DNA and cytotoxicity in vitro of dinuclear Pd(II) and Pt(II) complexes dibridged by 2,2'-azanediyldibenzoic acid

The dinuclear complexes [Pd₂(L)₂(bipy)₂] (1), [Pd₂(L)₂(phen)₂] (2), [Pt₂(L)₂(bipy)₂] (3) and [Pt₂(L)₂(phen)₂] (4), where bipy = 2,2′-bipyridine, phen = 1,10-phenanthroline and L = 2,2′-azanediyldibenzoic dianion) dibridged by H₂L ligands have been synthesized and characterized. The binding of the complexes with fish sperm DNA (FS-DNA) were investigated by fluorescence spectroscopy. The results indicate that the four complexes bound to DNA with different binding affinity, in the order complex 4 > complex 3 > complex 2 > complex 1, and the complex 3 binds to DNA in both coordination and intercalative mode. Gel electrophoresis assay demonstrates the ability of the complexes to cleave the pBR 322 plasmid DNA. The cytotoxic activity of the complexes was tested against four different cancer cell lines. The four complexes exhibited cytotoxic specificity and significant cancer cell inhibitory rate.