Estimations for HGT |
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Movement from organelle to nucleus:
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Dinoflagellates (Alveolates) |
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Dinoflagellate algae are unparalleled in their ability to capture photosynthetic organelles through endosymbiosis. Their plastid genome contains single-gene minicircles which encode an incomplete set of plastid proteins (~15). ESTs from Alexandria tamarense identify 48 photosynthetic genes in the nuclear genome. 15 of these genes are always found on the plastid genome of other algae and plants but have been transferred into this dinoflagellate. The plastid-targeted genes have red and green algal origins. The dinoflagellates encode the smallest number of plastid genes of any photosynthetic eukaryote. The single DNA-circle configuration of the plastid genome in apicomplexans, which contrasts with the unique minicircle plastid genes in peridinin dinoflagellates and the nuclear location of tufA in A. tamarense, suggests that extensive plastid gene transfer in dinoflagellates probably occurred independently after their split from apicomplexans. The extreme genome reduction evident in apicoplasts surely results from the evolution of an intracellular lifestyle with the loss of genes no longer needed for photosynthesis (e.g., as in the nonphotosynthetic parasitic plant Epifagus[29]). This type of reduction appears, however, to be quite different from that in dinoflagellates, many of which are photosynthetic and have for unknown reasons transformed the plastid genome required for this function into minicircles and undergone wholesale photosynthetic gene transfer to the nucleus. Hackett et al, 2004 Current Biology 14:213-218 Dinos have been stealing genes through history. 2 separate plastid transpormations in Dino (Bhattacharya) Dino mini circles may be the minimal gene set for a plastid. Alexandria tamaranse has over 200,000 Mg on 122 chromosomes, may use proteobacter LLP-bact-histones to package DNA (Wong et al 2003)
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Plastid genomes are typically AT rich |
Genes typicallay found on minicircles: atpA, atpB, petB, petD, psaA, psaB, psbA-E, ycf16, ycf24, rpl28, rpl23, 16S and 23S rRNA, and non-coding circles Psudogenes have been found on minicircles,16s, 23S, psbA, psbC, Zhang et al, 2001 MBE 19:1558-1565 |
Diatoms (Stramenophytes) |
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Ecology - in oceans 80% are phototrophic picoplankton, 20% are heterotrophs - Massona, Ventner SARS 11 are mostly <0.8, Copy # of rRNA in euks can range forom 1 - 10,000 (prok 1- 13). |