@misc{oai:tsukuba.repo.nii.ac.jp:00011274,
 author = {吉井, 幸恵},
 month = {},
 note = {application/pdf, Photosynthetic Antenna System in Green Plants : the Diversity and Evolution ~ 吉井，幸恵, 1. Composition of photosynthetic pigments in the members of the Prasinophyceae(Chlorophyta), a primitive paraphyletic group in green plants, was surveyed in detail from evolutionary interest. Mesostigma viride Lauterborn, the putatively most primitive green alga, contained two novel carotenoids, siphonaxanthin C12:0 exter and siphonaxanthin C14:0 ester. These siphonaxanthin series were esterified by the saturated fatty acids and have never been known. This alga also contained a unique carotenoid, all-trans neoxanthin. This carotenoid was detected in the chloroplasts of green plants for the first time. 9'-cis Neoxanthin, which is known as precursor of abscisic acid and universally present in the chloroplasts of green plants, was not found. Pterosperma cristatum Schiller(Pyramimonadales) had substantial amount of two novel carotenoids, siphonaxanthin C14:1 ester and 6'-OH siphonaxanthin C14:1 ester. This is the first report of carotenoid  C14:1 esters from photosynthetic organisms. In vivo absorption spectra and excitation spectra revealed that the siphonaxanthin series in these species functioned as blue-green light-absorbing antenna pigments. In the genus Nephroselmis, five carotenoid types were recognized: type I (N.astigmatica Inouye & Pienaar, N.intermedia Nakayama, nom.nud., and N.Pyriformis(N.Carter)Moestrup) had 6'-OH siphonaxanthin C12:1 and C14:1 esters and siphonaxanthin C12:1 and C14:1 esters, type II (Nephroselmis sp. MBIC 11149) had siphonaxanthin C8:1 ester, type III (N.spinosa Suda) had small amount of siphonaxanthin C12:1 ester, type IV (N.Viridis Inouye, nom.nud.) had 19-methoxy siphonaxanthin and siphonaxanthin C12:1 and C14:1 esters, type V (N.olivacea Stein) had no siphonaxanthin series but lutein as a major carotenoid. 19-Methoxy siphonaxanthin was a novel carotenoid and the methoxy group, which is a characteristic group of purple bacterial carotenoids, was found in photosynthetic eukaryotes for the first time. Siphonaxanthin C8:1 ester in Nephroselmis sp. MBIC 11149 was firstly found as a major carotenoid, which was known as a trace carotenoid only in Chlamydomonas parkeae Ettl(Chlorophyceae). From these results, I concluded that, in the early evolution of green plants, blue-green light-absorbing antenna systems using siphonaxanthin series would have evolved and diversified.

2. Photosynthetic pigments were analyzed by HPLC for 27 samples of the Cladophorales(Ulvophyceae, Chlorophyta). The carotenoid compositions of the examined alga were classified into three types with attention to final compound of biosynthesis of α-carotene branch: lutein type charatrerized by containing lutein as a major carotenoid and lacking loroxanthin and siphonaxanthin: loroxanthin type characterized by containing loroxanthin and lacking siphonaxanthin: siphonaxanthin type characterized by containing siphonaxanthin. I constructed molecular phylogenetic trees of the species examined in the present study using 18S rRNA gene sequences and mapped on it the carotenoid types of each species. The molecular phylogenetic analysis revealed two major clades within the Cladophorales, clade 1 and Aegagopila-clade(clade 2), and subclade 1-1 and subclade 1-2 within the clade 1. All the examined species positioned in the Aegagropila-clade and those of the subclade 1-1 belonged to the loroxanthin type, while both lutein type and siphonaxanthin type appeared only in the subclade 1-2. The clades delineated by molecular phylogenetic analysis were supported by distribution of the carotenoid types, and therefore, the carotenoid types seemed to be taxonomically significant. Considering the distribution pattern of these carotenoid types and major evolution of photosynthetic antenna system in green plants, I concluded that the cladophoralean loroxanthin and lutein types showed the advanced state of the antenna system of green plants and that the cladophoralean siphonaxanthin type would have secondarily appeared at the tip of the lineage of the Cladophorales.

3. Sequence of an Lhc cDNA from primitive green alga M.viride(Lhc*mv1) was determined. The amino acid sequence was homologous to the other Lhc family. Molecular phylogenetic analysis using Lhc protein sequence showed Lhc*mv1 diverged early in the Chl a/b-binding LHC lineage. Based on sequence comparison of Lhc proteins between eukaryotes including M.viride, pigment-binding sites were highly conservative. These results implicated that these pigment-binding sites would have obtained in the ancestor of the Lhc family. I performed protein structure prediction analyses on region corresponding to the N1 site of pea LHCII protein, in the Lhc family. From these results, Isuggested evolutionay pathway of Lhc proteins., Thesis (Ph. D. in Science)--University of Tsukuba, (A), no. 3552, 2004.6.30, Includes bibliographical references},
 title = {Photosynthetic antenna system in green plants : the diversity and evolution},
 year = {2004}
}