2004 HONOR B. FELL AWARD, 2004 CELLULAR TOXICOLOGY AWARD and 2004 JOSEPH F. MORGAN AWARD
Capacity of Fish Cell Lines to Undergo Apoptosis in Response to Two Toxicants: Gliotoxin and Copper

Although fish cell lines are widely used in toxicology and ecotoxicology, the mechanisms behind the death of the cells in response to toxicants is largely unexplored. Therefore, we compared the effects of two model toxicants, gliotoxin, a fungal metabolite and potent inducer of the intrinsic apoptotic pathway in mammals, and copper, a common ecotoxicant. Cell viability was assessed by monitoring energy metabolism with alamar Blue and plasma membrane integrity with 5-carboxyfluorescein diacetate acetoxymethyl ester (CFDA-AM). Apoptosis was identified by nuclear fragmentation using H33258 fluorescent staining, and internucleosomal fragmentation into 180bp oligomers using gel electrophoresis. For the rainbow trout (RT) macrophage cell line, RTS11, gliotoxin exposures as short as 6 h caused a loss of viability and apoptosis. Gliotoxin-induced RTS11 apoptosis was blocked by a pan caspase inhibitor but not by a translational inhibitor, cycloheximide, or by heat shock. Although less sensitive than RTS11, several RT cell lines underwent apoptosis in response to gliotoxin, including epithelial cell lines from gill (RTgilll-W1) and liver (RTL-W1). In contrast to gliotoxin, copper caused cell death in all cell lines tested, but without the hallmarks of apoptosis. In summary, all fish cell lines surveyed had the capacity to die by mitochondria-mediated apoptosis, but this pathway was not triggered by toxic concentrations of copper.

Stephanie DeWitte-Orr, University of Waterloo, Department of Biology, 200 University Ave., W.Waterloo, Ontario N2L 3G1, CANADA. In Vitro Cellular and Developmental Biology, 40: 78-A, 2004.

2004 SIVB STUDENT TRAVEL AWARD
Effect of Silver Nitrate on Organogenesis of Peanut (Arachis hypogaea L.).

Silver nitrate is known to be the inhibitor of the physiological action of ethylene and has been reported to improve morphogenetic efficiency in several species. Previous use of silver nitrate (AgNO3) in organogenesis of peanut was designed to assess the effect of culture temperature on regeneration protocols from cotyledon and leaf explants. In our experiments nodal explants were tested to determine the effect of different concentrations of AgNO3 on plant regeneration and multiple shoot formation at culture temperature of 25°C. Explants were cultivated on MS medium supplemented with BAP (0; 33; 66 M), NAA (0; 5,3; 15,9 M) and AgNO3(0; 23,54; 47,08; 70,62 M). The elongated shoots transfered to the rooting media supplemented with IBA (12,3 M) after 3 subcultures of 30 days each for the development and elongation of adventitious shoot buds. Rooted shoots were successfully transferred to soil and acclimatized.

Elif Aylin Ozudogru, Gebze Institute of Technology, Faculty of Science, Department of Biology, Plant Tissue Culture Laboratory, Cayirove Fabrikalar Yolu, No: 101, 41400, Gebze-Kocaeli, TURKEY. In Vitro Cellular and Developmental Biology, 40:46 -A, 2004.

2004 SIVB STUDENT TRAVEL AWARD
The Development of an Efficient Somatic Embryogenesis System in Potato

The process of somatic embryogenesis (SE), envisaging dedifferentiation and then redetermination of somatic plant cells towards the embryogenic pathway, is yet another way of exhibiting totipotency by plant cells and holds potential applications in both fundamental and applied aspects of plant development. Whilst the progress in the former aspect has progressed well using model plant species, the adoption of later aspect of SE in valuable crop species is less well developed, yet highly desirable. The present study is focused on developing and utilizing an efficient somatic embryogenesis system in potato (Solanum tuberosumL.) using internodal segments as principal explants for experimentation following a three-stage culturing regime viz. shoot multiplication, induction and expression of somatic embryogenesis on modified Murashige and Skoog (1962) medium with stage specific fortifications. The results were analysed as a function of genotypic differences, the effect of plant growth regulators (PGR), cultural conditions, and omission of either of the later stages. The key developmental stages during potato SE were analysed and confirmed using a histological approach. The SE response was visible within 3 weeks of explant transfer to auxin free medium, after an initial incubation for 2-3 weeks on auxin (alone or in combination with a cytokinin) containing medium. The transfer of potato somatic embryos to PGR free medium exhibited growth patterns similar to potato seedlings, in contrast to those observed in in vitro propagated shoots. Transplantation of emblings to glasshouse conditions resulted in potato plants and tubers with normal morphology. This somatic embryogenesis protocol offers a platform, not only for commercial production, but also as a novel biological system for studies on gene expression and regulation. Currently, the project involves the development of methods for characterization of potato SE as a function of differentially expressed SE specific marker gene and results from this aspect will also be presented.

Sanjeev Kumar Sharma, Scottish Crop Research Institute, Dept. of Gene Expression, Invergowrie, Dundee, Scotland DD2 5DA, UNITED KINGDOM. In Vitro Cellular and Developmental Biology, 40: 56-A, 2004.