ABSTRACT
DNA sequencing of randomly chosen clones from a cDNA library allows thousands of different transcripts to be identified. However, since the likelihood of observing a given transcript is proportional to the expression level of that transcript in the tissue from which the library is derived, often transcripts are represented by several EST sequences. An expressed sequence tags (EST) analysis was undertaken to identify the genes present in the leaves of Phyllanthus amarus, which is a small tropical, glabrous herb with several health benefits. Phyllanthin and hypophyllanthin, major bioactive components, present in highest amounts in the leaves, are of significant therapeutic importance like hepatoprotective, antioxidant, antiviral, hypoglycemic, etc. Taken together, sequencing of cDNA clones generated high-quality ESTs (Accession number: JK492908 to JK492964) with high similarities with genes from Ricinus communis, Onchocerca volvulus, Eucalyptus globules, Gossypium hirsutum, Nicotiana tabacum, Solanum spp. and many more. A BLASTN analysis along with BLASTX analysis of all the unique sequences was performed and was grouped according to the reported activities. Results represented here is the first reference collection of ESTs from this commercially important medicinal herb. This study indicated that the leaf transcriptome contains series of interesting sequences like ALBINO3, ribulose-1, 5 bisphosphate carboxylase/ oxygenase (RUBISCO), chloroplast photosystem II chlorophyll A/B-binding protein, stress-responsive proteins like methionine sulfoxide reductase type, etc.
ABSTRACT
Salicylic acid (SA) has been implicated in determining the outcome of interactions between many plants and their pathogens. Global changes in response to this phytohormone have been observed at the transcript level, but little is known of how it induces changes in protein abundance. To this end we have investigated the effect of 1 mM SA on soluble proteins of Arabidopsis thaliana leaves by proteomic analysis. An initial study at transcript level has been performed on temporal landscape, which revealed that induction of most of the SA-responsive genes occurs within 3 to 6 h post treatment (HPT) and the expression peaked within 24 HPT. Two-dimensional gel electrophoresis (2-DE) coupled with MALDI-TOF MS/MS analysis has been used to identify differentially expressed proteins and 63 spots have been identified successfully. This comparative proteomic profiling of SA treated leaves versus control leaves demonstrated the changes of many defence related proteins like pathogenesis related protein 10a (PR10a), diseaseresistance- like protein, putative late blight-resistance protein, WRKY4, MYB4, etc. along with gross increase in the rate of energy production, while other general metabolism rate is slightly toned down, presumably signifying a transition from ‘normal mode’ to ‘defence mode’.
ABSTRACT
A comparative analysis of earthworm communities was carried out in the rubber plantations (Hevea brasiliensis) of different age groups in West Tripura to understand the impact of such exotic and monoculture plantation in biodiversity conservation. Earthworm communities were studied on monthly basis over a period of one year (2006-2007) in the 3, 10, 14, 20 and 25 year-old plantations. Among twelve earthworm species collected from the studied sites, six species belonged to Octochaetidae [Eutyphoeus assamensis Stephenson, Eutyphoeus comillahnus Michaelsen, Lennogaster chittagongensis (Stephensen), Octochaetona beatrix Gates, Dichogaster affinis Michaelsen, Lennogaster yeicus (Stephensen)], two species each to Megascolecidae [Metaphire houlleti (Perrier), Kanchuria sp. 1] and Moniligastridae [Drawida nepalensis Michaelsen, Drawida papillifer papillifer Stephenson], one species each to Glossoscolecidae [Pontoscolex corethrurus (Muller)] and Ocnerodrilidae [Gordiodrilus elegans Beddard]. Exotic species P. corethrurus, M. houlleti and native peregrine species like D. nepalensis and D. papillifer papillifer were distributed in all the age groups of plantation, while other species showed restricted distribution. P. corethrurus contributed more than 60% biomass and 70% density of earthworm communities in rubber plantation. With aging of rubber plantations both the densities and biomasses of earthworms increased. High contents of polyphenol, flavonoid and lignin in the litters of 3 and 10 year-old-rubber plantations through their effects on food intake, probably resulted to low biomass values of earthworms in those age groups of plantation. With further increase in the age of plantations beyond 10 years, polyphenol, flavonoid and lignin contents decreased. Accordingly the biomass of earthworms increased with increase in the age of plantation. Soil moisture increased with increase in the age of plantation and there was a good positive correlation between soil moisture and earthworm biomass (p<0.01). Density, biomass and dominance of earthworms increased while species diversity, species richness and species evenness of earthworm community were decreased with increase in the age of rubber plantation.