Complete gene map of the plastid genome of the nonphotosynthetic euglenoidflagellate Astasia longa

Astasia longa is a colourless heterotrophic flagellate closely related to t he photoautotrophic Euglena gracilis. A circular 73 kb plastid DNA (ptDNA) has been isolated from A. longa that is about half the size of the chloropl ast DNA of E. gracilis (143 kb). We have determined the complete sequence o f the ptDNA of A. longa and established a complete gene map. All chloroplas t genes for photosynthesis-related proteins are completely absent from the A. longa plastid DNA except for rbcL, the gene for the ribulose-l,5-bisphos phate carboxylase large subunit, Identified genes encode components of the plastid transcriptional and translational machinery: genes for three subuni ts of a chloroplast RNA polymerase, 20 chloroplast ribosomal protein genes, a gene for a plastid elongation factor Tu, 27 plastidic tRNA genes and thr ee tandemly arranged repeats of 16S, 23S and 5S rDNA, Transcripts of a numb er of genes were detected by Northern hybridisation, The ribulose-l,5-bisph osphate carboxylase large subunit protein has been identified by immunoblot ting.