ALKB-8 is a 2-oxoglutarate-dependent dioxygenase homologous to bacterial AlkB, which oxidatively demethylates DNA substrates. The mammalian AlkB family contains AlkB homologues denominated ALKBH1 to 8 and FTO. The C. elegans genome includes five AlkB-related genes, homologues of ALKBH1, 4, 6, 7, and 8, but lacks homologues of ALKBH2, 3, and 5 and FTO. ALKBH8 orthologues differ from other AlkB family members by possessing an additional methyltransferase module and an RNA binding N-terminal module. The ALKBH8 methyltransferase domain generates the wobble nucleoside 5-methoxycarbonylmethyluridine from its precursor 5-carboxymethyluridine and its (R)- and (S)-5-methoxycarbonylhydroxymethyluridine hydroxylated forms in tRNA Arg/UCG and tRNA Gly/UCC. The ALKBH8/ALKB-8 methyltransferase domain is highly similar to yeast TRM9, which selectively modulates translation of mRNAs enriched with AGA and GAA codons under both normal and stress conditions. In this report, we studied the role of alkb-8 in C. elegans. We show that downregulation of alkb-8 increases detection of lysosome-related organelles visualized by Nile red in vivo. Reversely, forced expression of alkb-8 strongly decreases the detection of this compartment. In addition, overexpression of alkb-8 applied in a pulse during the L1 larval stage increases the C. elegans lifespan.

• MeSH
• Caenorhabditis elegans embryology   enzymology   genetics   MeSH
• Dioxygenases metabolism   MeSH
• Longevity MeSH
• Down-Regulation genetics   MeSH
• Embryo, Nonmammalian metabolism   MeSH
• Animals, Genetically Modified MeSH
• Ketoglutaric Acids metabolism   MeSH
• Larva metabolism   MeSH
• Lysosomes metabolism   MeSH
• Methyltransferases metabolism   MeSH
• Operon MeSH
• Promoter Regions, Genetic MeSH
• Caenorhabditis elegans Proteins genetics   metabolism   MeSH
• RNA Interference MeSH
• S-Adenosylmethionine metabolism   MeSH
• Aging metabolism   MeSH
• Gene Expression Regulation, Developmental MeSH
• Green Fluorescent Proteins metabolism   MeSH
• Animals MeSH
• Check Tag
• Animals MeSH
• Publication type
• Journal Article MeSH

Cytokinins (CKs) as well as the antioxidant enzyme system (AES) play important roles in plant stress responses. The expression and activity of antioxidant enzymes (AE) were determined in drought, heat and combination of both stresses, comparing the response of tobacco plants overexpressing the main cytokinin degrading enzyme, cytokinin oxidase/dehydrogenase, under the control of root-specific WRKY6 promoter (W6:CKX1 plants) or constitutive promoter (35S:CKX1 plants) and the corresponding wild-type (WT). Expression levels as well as activities of cytosolic ascorbate peroxidase, catalase 3, and cytosolic superoxide dismutase were low under optimal conditions and increased after heat and combined stress in all genotypes. Unlike catalase 3, two other peroxisomal enzymes, catalase 1 and catalase 2, were transcribed extensively under control conditions. Heat stress, in contrast to drought or combined stress, increased catalase 1 and reduced catalase 2 expression in WT and W6:CKX1 plants. In 35S:CKX1, catalase 1 expression was enhanced by heat or drought, but not under combined stress conditions. Mitochondrial superoxide dismutase expression was generally higher in 35S:CKX1 plants than in WT. Genes encoding for chloroplastic AEs, stromatal ascorbate peroxidase, thylakoidal ascorbate peroxidase and chloroplastic superoxide dismutase, were strongly transcribed under control conditions. All stresses down-regulated their expression in WT and W6:CKX1, whereas more stress-tolerant 35S:CKX1 plants maintained high expression during drought and heat. The achieved data show that the effect of down-regulation of CK levels on AES may be mediated by altered habit, resulting in improved stress tolerance, which is associated with diminished stress impact on photosynthesis, and changes in source/sink relations.

• MeSH
• Antioxidants metabolism   MeSH
• Arabidopsis enzymology   genetics   MeSH
• Ascorbate Peroxidases metabolism   MeSH
• Models, Biological MeSH
• Cytokinins metabolism   MeSH
• Down-Regulation MeSH
• Photosynthesis MeSH
• Stress, Physiological MeSH
• Plants, Genetically Modified MeSH
• Catalase metabolism   MeSH
• Plant Roots enzymology   genetics   MeSH
• Plant Leaves enzymology   genetics   physiology   MeSH
• Droughts MeSH
• Oxidoreductases genetics   metabolism   MeSH
• Promoter Regions, Genetic genetics   MeSH
• Arabidopsis Proteins genetics   metabolism   MeSH
• Gene Expression Regulation, Plant * MeSH
• Superoxide Dismutase metabolism   MeSH
• Nicotiana enzymology   genetics   physiology   MeSH
• Hot Temperature MeSH
• Publication type
• Journal Article MeSH