Indications of limited altered gene expression in Pinus sylvestris trees from the Chernobyl region L. Zelena a , B. Sorochinsky a , S. von Arnold b , L. van Zyl c , D.H. Clapham b, * a Department of Biophysics and Radiobiology, Institute of Cell Biology and Genetic Engineering, 148 Zabolotnogo Street, Kyiv 03143, Ukraine b Department of Plant Biology and Forest Genetics, Swedish University of Agricultural Sciences, Box 7080, S-750 07 Uppsala, Sweden c Forest Biotechnology Group, 2500 Partners II, 840 Main Campus Drive, Centennial Campus, Box 7247, North Carolina State University, Raleigh, NC 27695, USA Received 5 November 2004; received in revised form 7 March 2005; accepted 17 March 2005 Available online 14 June 2005 Abstract To evaluate the consequences of irradiation on the vegetation of the Chernobyl region, gene expression was compared in morphologically normal and dwarf needles from the same Pinus sylvestris trees in a region where the absorbed dose was 3e5 Gy. To compare the levels of gene expression, arrays consisting of 373 Pinus taeda cDNAs were hybridized with labeled cDNA derived from normal and dwarf needles of P. sylvestris. Twelve genes were significantly (P ! 0.01) up- or down-regulated between normal and dwarf needles for all five trees taken together. Five of these, related to stress or development, were up- or down-regulated 1.25e1.7- fold in the dwarf needles. There were no significant differences in 137 Cs content in the normal and dwarf needles, or in elongation growth rate of seedlings raised under controlled Abbreviations: cDNA, complementary deoxyribonucleic acid; EST, expressed sequence tag; Gy, gray; PCR, polymerase chain reaction; R, Roentgen. * Corresponding author. Tel.: C46 18 67 32 35; fax: C46 18 67 32 79. E-mail address: david.clapham@vbsg.slu.se (D.H. Clapham). 0265-931X/$ - see front matter Ó 2005 Elsevier Ltd. All rights reserved. doi:10.1016/j.jenvrad.2005.03.008 Journal of Environmental Radioactivity 84 (2005) 363e373 www.elsevier.com/locate/jenvrad