C3.11Ecotoxicological analysis using transcriptomic screeningtechnology

A. Cossins (University of Liverpool); A. Sawle (University of Liverpool);G. Whale (Shell Global)

Animals are frequently exposed to anthropogenic pollutants whichcause sub-lethal aswell as themore obvious lethal effects. Understandingthese effects and the potential for protective responses is important foranyappreciation of the ecological effects of exposure.Wehave developedan array-based approach to the analysis of effect using the zebrafishembryomodel, and a large-scale oligomicroarray. Embryoswere exposedcontinuously to each of 4 different compounds over 72 h, and wholeembryo RNAs extracted and applied to a 16 K array printed in-house ontoNexterion Hi-sens slides using a balanced interwoven ANOVA design.This revealed a large number of responding genes which were clusteredinto 12 groups using QT analysis. The roles of genes within each groupwere explored usingGO categorisation andREACTOMEprofiling analysis.This indicated that each compound elicited responses from distinctgroups of genes, and that these genes mapped to coherent metabolicpathways, revealing information onmode-of-action for each compound.Responses were observed at low, sub-lethal doses, indicating that thistechnique gives important information at levelswhich have limited or nomorphological effect on development.

doi:10.1016/j.cbpa.2008.04.409

C3.12The wheat GCN2 signalling pathway: Does this kinase play animportant role in stress signalling?

E. Byrne (Rothamsted Research); A. Wingler (University CollegeLondon), N. Muttucumaru (Rothamsted Research); N. Halford(Rothamsted Research)

Whenyeast andmammalian cells are starved of amino acids, generalprotein synthesis is down-regulatedwhilst genes involved in the aminoacid biosynthetic pathway are up-regulated; this helps the cell tomaintain homeostasis and survive. This paradox is controlled by aprotein kinase that phosphorylates the eukaryotic translation initiationfactor eIF2a; the kinase is General Control Non-derepessible-2 (GCN2).

This activation pathway has been well characterised in alleukaryotic kingdoms except plants. Recently, however, GCN2 wascloned from Arabidopsis, suggesting that plants also have a co-ordinated response to amino acid starvation induced by GCN2. Thepotential link between amino acid signalling and nitrogen-useefficiency makes the study of this regulatory protein kinase ofparticular importance in crops.

The aim of this research is to elucidate the GCN2 signallingpathway in Triticum aestivum (TaGCN2) by identifying, cloning andcharacterising TaGCN2 as well as upstream and downstream effectors.

Latest research frommammalian systems suggests that GCN2 mayplay a wider role in virus defence and UV light stress. Data will bepresented on the characterisation of TaGCN2 and the expression inresponse to nutrient deficiency, UV light and other abiotic stresses.Using RNAi, we have manipulated GCN2 activity in wheat seeds andwhole plants and the effects on the GCN2 signalling pathway in theseplants will be discussed.

doi:10.1016/j.cbpa.2008.04.410

C3.13In vivo and in vitro high accumulation of cadmium in licorice(Glycyrrhiza glabra L.)

F. Bernard, H. Shaker Bazarnov, M. Sarmadi, M. Irani (Shahid BeheshtiUniversity)

Licorice (Glycyrrhiza glabra) is one of the most extensively usedand scientifically investigated herbal medicines. Due to the largeuses of licorice products for food industry and medicinal purposesit is important to control the quality of the products. The licoricetolerance to cadmium (Cd) and the accumulation of this toxicheavy metal were investigated in plantlets and callus tissues. Theseeds of two varieties (glabra and glandulifera) of G. glabra weregerminated in soil added with 200 µM cadmium chloride solutionand 20 days old plantlets were used for analysis. Calluses, obtainedfrom roots culture, were treated by 200 µM cadmium chlorideadded to agar culture medium for 2 weeks. Application of highdose of Cd did not inhibit the germination of licorice seeds andthe growth of plantlets was little affected. No metal-toxicitysymptoms such as burning and redness of the tissues were ob-served although high amounts of Cd were accumulated in shoottissues of varieties glabra and glandulifera (116.9±1.5 and 119.57±7.2 mg kg−1 dw, respectively). Impressive increase of Cd werenoted in callus tissues (1046.6±91 mg kg−1 dw for glabra and1266.66±87 mg kg−1 dw for glandulifera) and tissues growthdecreased by 21% under Cd stress. Cd treatment significantlyincreased peroxidase activity and prolin content but malondialde-hyde (MDA) content, a lipid peroxidation indicator, did not changed.By these results it is shown that plantlets and callus tissues oflicorice were able to accumulate very high amounts of Cd without alot of damage and licorice may be consider as hyperaccumulator ofthis heavy metal.

Keywords: Hyperaccumulator; Prolin; Peroxidase;Malondialdehyde

doi:10.1016/j.cbpa.2008.04.411

C3.14Protection of photosynthesis against solar UV radiation bydifferent screening compounds in the benthic blue–green algaeHydrococcus cesatti

A. Botha-Oberholster (University of Pretoria), P. Oberholster (CSIR:NRE)

The recent interest in phytoplankton as bioindicator species tostudy stress associated with high levels of UVB radiation has grown,due to evidence that levels of ambient UV-B radiation are increasing inresponse to stratospheric ozone depletion. Here we report that theaquatic benthic blue–green Hydrococcus cesatti not only uses passivescreening compounds to copewith high levels of UV radiation, but alsothe induction of other photo-protection mechanisms or physiologicalresponses to survive for a two month-period outside their aquaticenvironment after the drainage of an earth dam in the Kruger NationalPark, South Africa. The ratio of thylakoid carotenoid pigments tochlorophyll a revealed that carotenoids may contribute to coping withstress associated with high radiation. The orange coloured colonies ofHydrococcus had a high OD ratio of 471 to 664 nm. None of the Hy-drococcus cesatti colonies examined during this study possessedsheaths containing the UVA-absorbing pigment, scytonemin. How-ever, Mycosporine-like amino acids (MAA) were present in largequantities in the-material assayed, as evidenced by thehigh absorptionpeak at 311–339 nm,which is characteristic to these compounds. From

S158 Abstracts / Comparative Biochemistry and Physiology, Part A 150 (2008) S155–S161