Certain classes of bioactive compounds can be separated using planar chromatography. Some biological effects (e.g. antibacterial) of these compounds can be investigated directly by examining the growth of a test organism on a specially treated sorbent of thin layer chromatography (TLC). A special method of detection, direct bioautography, is suitable for studying the antimicrobial activity of plant extracts of natural origin by using TLC. Zones of inhibition are visualised by use of a dehydrogenase-activity-detecting, tetrazol-type reagent. Zones of inhibition appeared as pale spots separating well from the dark background. The antibacterial effect of the main essential oil components of some Thymus taxa, as well as that of two antibiotics (streptomycin sulphate and gentamycin) known and applied in practice was investigated against plant pathogenic bacteria. Results showed that thyme essential oil and its components inhibited the growth of test bacteria, but not so considerably as the antibiotics applied. Compositions of the essential oils were analysed by gas chromatography (GC). It could be verified that among the essential oil components, thymol and carvacrol had the strongest inhibitory effect.
The authors have developed transgenic wheat lines with broad range of herbicide resistance. The transgenic wheat, containing bacterial derived alien gene (bar) regulated under the maize ubiquitin promoter, is resistant to glyphosinate (phosphinotrichin) agent family. The presence of bar gene expression product (phosphinotrichin acetyl transpherase enzyme, PAT) was confirmed by PAT-specific ELISA (Enzyme Linked Immuno Sorbent Assay). The qualitative and quantitative chemical composition of the transgenic wheat lines in comparison with their non-transgenic counterpart (year 2000-2002) and protein utilization of the wheat wholemeal flours (year 2002) were summarized. Nutritional evaluation of the protein was based on a rat model by using N-balance experiments. Among the protein sources, heat-treated samples were also introduced into the experimental diets. It was found that heat denaturation of the proteins led to results with somewhat increased biological value indices. The introduction of GM technology did not affect food intake or nutritional performance of the rats.
A new necrosis viral disease was observed in blackgram, showed brown necrotic rings along with veinal and stem necrosis. The virus was mechanically inoculated on the local lesion host, cowpea cv. 152 and maintained in the local lesion host throughout the study. Yield studies under pot culture experiment showed 10- to 30-day-old plants were highly susceptible and the yield became almost nil. By using Transmission Electron Microscope (TEM) and indirect Direct Antigen Coated-Enzyme Linked Immuno-Sorbent Assay (DAC-ELISA) studies the virus was identified as Tobacco streak virus (TSV). The ultraviolet absorbance of the purified virus was measured and the ratio of A260/A280 was determined as 1.41. Polyclonal antiserum was raised against blackgram necrosis virus in New Zealand white rabbit and the titre value was determined as 1: 200. Direct antigen coating-ELISA was used to detect the virus concentration in various plant parts and stem portion recorded maximum virus concentration. TSV in blackgram was not transmitted through seeds.
C e: equilibrium concentration of adsorbate q e & Q e: amount of sorbed per gram of adsorbent Q 0: maximum monolayer coverage capacity of sorbent K L: Langmuir isotherm constant related to the energy of adsorption