Detection of Uranium Contamination in Acacia Cell Sap by Capillary Zone Electrophoresis (CZE) Technique

The  study was carried out to detect uranium level in the cell sap of acacia plant cells, for this purpose callus cultures of Acacia albida was used as well as plants. Cell saps from both callus and plant leaf were taken using Micro capillary syringe and detected using Capillary zone electrophoresis technique. It was shown that using citrate buffer of 3.0pH help in detecting uranium accumulated in the cells. Prospective calculation for the level of uranium uptake showed that 1.64mM is the level of uranium in the leaf cells that had been grown on soil with addition of 500 mg.kg-1 uranyl nitrate for 3 months, while for callus which grown on MS medium with addition of 500 mg/l uranyl nitrate for the same time (3 months), uptake of uranium reached 0.8 mM. The comparison between TXRF analysis of uranium accumulated in plant tissues and CZE efficiency in detecting uranium level in cell sap of both leaves and callus cells, it was shown that both techniques prove that A.albida plants can accumulate uranium with a level double as that taken by callus cells. Keywords : Capillary Zone Electrophoresis, Acacia albida, Uraniu

Correlation Network Analysis reveals a sequential reorganization of metabolic and transcriptional states during germination and gene-metabolite relationships in developing seedlings of Arabidopsis

<p>Abstract</p> <p>Background</p> <p>Holistic profiling and systems biology studies of nutrient availability are providing more and more insight into the mechanisms by which gene expression responds to diverse nutrients and metabolites. Less is known about the mechanisms by which gene expression is affected by endogenous metabolites, which can change dramatically during development. Multivariate statistics and correlation network analysis approaches were applied to non-targeted profiling data to investigate transcriptional and metabolic states and to identify metabolites potentially influencing gene expression during the heterotrophic to autotrophic transition of seedling establishment.</p> <p>Results</p> <p>Microarray-based transcript profiles were obtained from extracts of Arabidopsis seeds or seedlings harvested from imbibition to eight days-old. ¹H-NMR metabolite profiles were obtained for corresponding samples. Analysis of transcript data revealed high differential gene expression through seedling emergence followed by a period of less change. Differential gene expression increased gradually to day 8, and showed two days, 5 and 7, with a very high proportion of up-regulated genes, including transcription factor/signaling genes. Network cartography using spring embedding revealed two primary clusters of highly correlated metabolites, which appear to reflect temporally distinct metabolic states. Principle Component Analyses of both sets of profiling data produced a chronological spread of time points, which would be expected of a developmental series. The network cartography of the transcript data produced two distinct clusters comprising days 0 to 2 and days 3 to 8, whereas the corresponding analysis of metabolite data revealed a shift of day 2 into the day 3 to 8 group. A metabolite and transcript pair-wise correlation analysis encompassing all time points gave a set of 237 highly significant correlations. Of 129 genes correlated to sucrose, 44 of them were known to be sucrose responsive including a number of transcription factors.</p> <p>Conclusions</p> <p>Microarray analysis during germination and establishment revealed major transitions in transcriptional activity at time points potentially associated with developmental transitions. Network cartography using spring-embedding indicate that a shift in the state of nutritionally important metabolites precedes a major shift in the transcriptional state going from germination to seedling emergence. Pair-wise linear correlations of transcript and metabolite levels identified many genes known to be influenced by metabolites, and provided other targets to investigate metabolite regulation of gene expression during seedling establishment.</p

Ozone alters the intercellular distribution of Calcium (Ca2+) in cereal leaf epidermis [abstract]

Ozone is known to damage membranes in leaf tissue. This is likely to have an effect on both the intra- and the inter-cellular compartmentation of solutes found in leaves. Vacuolar Ca'­ was measured in individual epidermal cells of ozone-treated (70 ppb) and control barley leaves, by means of micro-droplet X-ray microanalysis. Significantly higher Ca'; concentrations were found in ozone fumigated plants. Stomatal conductance was reduced in ozone fumigated plants during, and also the day following exposure. Turgor pressure(P) in both transpiring and non-transpiring tissue was reduced in individual cells in 03-treated plants. The osmotic pressure (re) was found to be unaltered. Therefore, 03 makes the water potential (1) more negative. The decrease in 'I' was considerably greater than any change in the wall hydrostatic tension indicating that the 03-induced decrease in 1 is due to an increase in wall re. The ozone-induced increase in cell wall re may be due either to increased solute leakage from the cells or to an impaired solute uptake system. In control plants a hydrostatic pressure gradient appeared to occur in the cell wall away from the stomata. This was abolished by 03. The water relations, and stomatal conductance measurements show, independently, that the increase in Ca'" i n 03-trcated plants is not due to an increase in transpiration. These results support the hypothesis that ozone causes changes to membrane permeability

Intracellular and intercellular compartmentalisation of carbohydrate metabolism in leaves of temperate gramineae

This review considers the importance of compartmentation in the regulation of carbohydrate metabolism in leaves. We draw particular attention to the role of the vacuole as a site for storage of soluble sugars based on sucrose, and discuss briefly their characteristic metabolism. We also point out inconsistencies between the observed properties of vacuoles and the behaviour in vitro of the enzymes of fructan biosynthesis that do not support the hypothesis that the vacuole is the site of synthesis as well as of storage. We also consider compartmentation of carbohydrate metabolism between different cell types, using mainly our studies on leaves of temperate C3 gramineae. Here we present evidence of significant differences in carbon metabolism between epidermis, mesophyll, bundle sheath and vasculature based upon both single-cell sampling and immunolocalisation. The implications of these differences for the control of metabolism in leaves are discussed