A highly reliable, quantitative and sensitive analytical method for determining the residues of the fungicide, hexaconazole in black tea is described. The proposed method is based on liquid-liquid extraction followed ...A highly reliable, quantitative and sensitive analytical method for determining the residues of the fungicide, hexaconazole in black tea is described. The proposed method is based on liquid-liquid extraction followed by gas chromatographic determination, using nitrogen phosphorus detector (GC-NPD) for the identification and quantitation of hexaconazole. The most appropriate solvent mixture for extracting hexaconazole residues from black tea was n-hexane:acetone at 1:1 (v/v). The extract was cleaned up by adsorption column chromatography using activated florisil. Performance of the method was assessed by evaluating quality parameters such as recovery value, repeatability, reproducibility, linearity and limits of detection and quantitation. When the method was assessed for repeatability, the percentage of recovery ranged between 86% and 96% while the relative standard deviation was between 0.30% and 2.35%. In studies on reproducibility the recovery ranged from 81% to 85% and relative standard deviation from 1.68% to 5.13%, implying that the method was reliable. A field trial was conducted to verify the application of this method with real samples. Results prove that the validated method was suitable for extracting hexaconazole residues.展开更多
The effect of bavistin and the ethylene inhibitor (silver thiosulphate) on shoot regeneration using nodal explants of Asclepias curassavica (L). has been investigated. Among the different concentrations studied, highe...The effect of bavistin and the ethylene inhibitor (silver thiosulphate) on shoot regeneration using nodal explants of Asclepias curassavica (L). has been investigated. Among the different concentrations studied, highest number of shoots was obtained on MS media with 200 mg/L bavistin. Among the varying concentrations (10-100 μM/L) of silver thio-sulphate tested, highest number of shoots was obtained on MS medium amended with 60 μM/L silver thiosulphate without growth regulators. This study also establishes the stronger cytokinin like activity of bavistin. Effect of different growth additives like coconut milk, ascorbic acid and casein hydrolysate were tested on direct shoot regeneration. Among the different growth additives tested casein hydrolysate showed better and reproducible result at 0.025% in combination with 3 mg/l KN + 0.5 mg/l NAA. Antioxidants, activated charcoals and polyvinyl pyrrolidone were used to remove phenolics. Activated charcoal removed the phenolic exudates completely at 0.025% and prevented the browning of media and thus enhanced the frequency of regeneration (85%). The microshoots developed through in vitro regeneration were transferred to rooting media containing IBA alone and in combination with KN and the highest number of roots was observed on MS medium with IBA 1 mg/L + 0.2 mg/L KN.展开更多
MicroRNAs （miRNAs） are a newly identified class of small non-protein-coding post-transcriptional regulatory RNA in both plants and animals. The use of computational homology based search for expressed sequence tags ...MicroRNAs （miRNAs） are a newly identified class of small non-protein-coding post-transcriptional regulatory RNA in both plants and animals. The use of computational homology based search for expressed sequence tags （ESTs） with the Ambros empirical formula and other structural feature criteria filter is a suitable combination towards the discovery and isolation of conserved miRNAs from tea and other plant species whose genomes are not yet sequenced. In the present study, we blasted the database of tea （Camellia sinensis） ESTs to search for potential miRNAs, using previously known plant miRNAs. For the first time, four candidate miRNAs from four families were identified in tea. Using the newly identified miRNA sequences, a total of 30 potential target genes were identified for 11 miRNA families; 6 of these predicted target genes encode transcription factors （20%）, 16 target genes appear to play roles in diverse physiological processes （53%） and 8 target genes have hypothetical or unknown functions （27%）. These findings considerably broaden the scope of understanding the functions of miRNA in tea.展开更多
基金Project supported by the National Tea Research Foundation, Kolkata,India
文摘A highly reliable, quantitative and sensitive analytical method for determining the residues of the fungicide, hexaconazole in black tea is described. The proposed method is based on liquid-liquid extraction followed by gas chromatographic determination, using nitrogen phosphorus detector (GC-NPD) for the identification and quantitation of hexaconazole. The most appropriate solvent mixture for extracting hexaconazole residues from black tea was n-hexane:acetone at 1:1 (v/v). The extract was cleaned up by adsorption column chromatography using activated florisil. Performance of the method was assessed by evaluating quality parameters such as recovery value, repeatability, reproducibility, linearity and limits of detection and quantitation. When the method was assessed for repeatability, the percentage of recovery ranged between 86% and 96% while the relative standard deviation was between 0.30% and 2.35%. In studies on reproducibility the recovery ranged from 81% to 85% and relative standard deviation from 1.68% to 5.13%, implying that the method was reliable. A field trial was conducted to verify the application of this method with real samples. Results prove that the validated method was suitable for extracting hexaconazole residues.
文摘The effect of bavistin and the ethylene inhibitor (silver thiosulphate) on shoot regeneration using nodal explants of Asclepias curassavica (L). has been investigated. Among the different concentrations studied, highest number of shoots was obtained on MS media with 200 mg/L bavistin. Among the varying concentrations (10-100 μM/L) of silver thio-sulphate tested, highest number of shoots was obtained on MS medium amended with 60 μM/L silver thiosulphate without growth regulators. This study also establishes the stronger cytokinin like activity of bavistin. Effect of different growth additives like coconut milk, ascorbic acid and casein hydrolysate were tested on direct shoot regeneration. Among the different growth additives tested casein hydrolysate showed better and reproducible result at 0.025% in combination with 3 mg/l KN + 0.5 mg/l NAA. Antioxidants, activated charcoals and polyvinyl pyrrolidone were used to remove phenolics. Activated charcoal removed the phenolic exudates completely at 0.025% and prevented the browning of media and thus enhanced the frequency of regeneration (85%). The microshoots developed through in vitro regeneration were transferred to rooting media containing IBA alone and in combination with KN and the highest number of roots was observed on MS medium with IBA 1 mg/L + 0.2 mg/L KN.
文摘MicroRNAs （miRNAs） are a newly identified class of small non-protein-coding post-transcriptional regulatory RNA in both plants and animals. The use of computational homology based search for expressed sequence tags （ESTs） with the Ambros empirical formula and other structural feature criteria filter is a suitable combination towards the discovery and isolation of conserved miRNAs from tea and other plant species whose genomes are not yet sequenced. In the present study, we blasted the database of tea （Camellia sinensis） ESTs to search for potential miRNAs, using previously known plant miRNAs. For the first time, four candidate miRNAs from four families were identified in tea. Using the newly identified miRNA sequences, a total of 30 potential target genes were identified for 11 miRNA families; 6 of these predicted target genes encode transcription factors （20%）, 16 target genes appear to play roles in diverse physiological processes （53%） and 8 target genes have hypothetical or unknown functions （27%）. These findings considerably broaden the scope of understanding the functions of miRNA in tea.
