Pigment composition of putatively achlorophyllous angiosperms

Chlorophyll and carotenoid pigment composition was determined for ten species of putatively achlorophyllous angiosperms using high-performance liquid chromatography. Four families were represented:Lennoaceae (Pholisma arenarium);Monotropaceae (Allotropa virgata, Monotropa uniflora, Pterospora andromedea, Sarcodes sanguinea); Orobanchaceae (Epifagus virginiana, Orobanche cooperi, O. uniflora);Orchidaceae (Cephalanthera austinae, Corallorhiza maculata). Chlorophylla was detected in all taxa, but chlorophyllb was only detected inCorallorhiza maculata. The relative amount of chlorophyll and chlorophyll-related pigments in these plants is greatly reduced compared to fully autotrophic angiosperms.     

Multiple pathways of excitation energy flow in the photosynthetic pigment system of a cryptophyte,Cryptomonas sp. (CR-1)*

Energy transfer pathways in a cryptophyte, Cryptomonas sp. (CR-1 strain) were investigated mainly by the steady state fluorescence spectroscopy and the time-resolved spectrum. Cryptomonas sp. (CR-1) contains chlorophyll (Chi) a, Chi c₂, carotenoids and cryptomonad phycoer-ythrin (Cr-PE₅₆₅), the last of which is known to be located in the lumenal side of the thyiakoid membranes. The spectral heterogeneity cf pigments was resolved by fluorescence spectra; there were at least five emission bands of Chi a at -196°C. Chlorophyll C₂ and carotenoids transferred independently to the common Chi a form (Chi a₆₆₃), and Cr-PE₅₆₅, to the different form (Chi a₆₈₂). Chlorophyll c₂ was not an intermediary component of energy transfer from carotenoid to Ch a; this is a common phenomenon to green algae and brown algae. The Chi a₆₆₃ and Chi a₆₈₂ are postulated to be located in the light-harvesting chlorophyll protein (LHC) II; thus, the energy is accumulated on Chi a₆₈₂‘n LHC II. The energy transfer step in Cr-PE_;565, was short, which was shown by a small, time-dependent red-shift of the emission. In the photosystem (PS) II core, two fluorescence components were resolved at 688 and 696 nm. The former was the trap at cryogenic temperatures. A large red-shift induced by the low temperature was explained by an equilibrium between Chi a₆₈₂ in LHC II and Chi a₆₈₈ in PS II core. The presence of Chi a₆₈₂ emission at physiological temperature is a unique feature of this alga. This was also reported in dinophyceae, which contain peridinin-ChI a-protein in the lumenal side of the thyiakoid membrane. Thus, this modification might be common in systems where the antenna complexes bind to the LHC II on the lumenal side. Based on the spectral data, we proposed a model for the molecular organization of PS II and the energy transfer pathways in cryptophyceae.     

CAROTENOID COMPOSITIONS OF CLADOPHORA BALLS (AEGAGROPILA LINNAEI) AND SOME MEMBERS OF THE CLADOPHORALES (ULVOPHYCEAE,CHLOROPHYTA): THEIR TAXONOMIC AND EVOLUTIONARY IMPLICATION1

Photosynthetic pigments were analyzed by HPLC for 27 samples of the Cladophorales (Ulvophyceae, Chlorophyta). The carotenoid compositions of the examined algae were classified into three types based on the final compound of biosynthesis of the α‐carotene branch: lutein type, characterized by containing lutein as a major carotenoid and lacking loroxanthin and siphonaxanthin; loroxanthin type, characterized by containing loroxanthin and lacking siphonaxanthin; and siphonaxanthin type, characterized by containing siphonaxanthin. We constructed molecular phylogenetic tree of the species examined in the present study using 18S rRNA gene sequences and mapped the carotenoid types of the species onto the tree. The molecular phylogenetic analysis divided the Cladophorales into two major clades, clade 1 and Aegagropila‐clade (clade 2), and divided clade 1 into subclade 1‐1 and subclade 1‐2. All the examined species positioned in the Aegagropila‐clade and those of the subclade 1‐1 belonged to the loroxanthin type, whereas both lutein type and siphonaxanthin type appeared only in the subclade 1‐2. The clades delineated by molecular phylogenetic analysis were congruent with distribution of the carotenoid types, indicating that the carotenoid types are of taxonomic significance in the Cladophorales. Considering the distribution pattern of these carotenoid types and minimum state changes in the Cladophorales, we concluded that the loroxanthin type was the primitive (plesiomorphic) state and the siphonaxanthin type and lutein type appeared in the subclade 1‐2 as advanced (apomorphic) state within this order and suggested that the cladophoralean siphonaxanthin type would have been secondarily acquired.     

Genome Analysis inNeurospora crassa;Cloning of Four Lociarginine-1(arg-1),methionine-6(met-6),unknown-7(un-7), andribosome production-1(rip-1) and Associated Chromosome Walking

We have cloned fourNeurospora crassagenes by complementation analysis. Cloned genes include thearginine-1(arg-1),methionine-6(met-6),unknown-7(un-7), andribosome production-1(rip-1) loci. Chromosome walks were initiated in ordered cosmid libraries from the cloned loci. A total of about 700 kb of theNeurosporagenome is covered in these walks.     

Expression of the farnesyldiphosphate synthase gene of Saccharomyces cerevisiae in tobacco

The coding region of the farnesyldiphosphate synthase (FDP synthase) gene from Saccharomyces cerevisiae has been inserted into a pBin19 vector, downstream of the cauliflower mosaic virus (CaMV) 35S promoter, in order to allow its expression in the genome of a higher plant, Nicotiana tabacum. We have produced transgenic tobacco in which the expression of the foreign gene leads to functional FDP synthase activity. In these transgenic plants, total FDP synthase-specific activity is increased 12-fold compared to controls. This increase of FDP synthase activity has been correlated to a clear increase of both sterol and carotenoid biosynthesis. This heterologous expression is also related to an increased resistance of transformed plants to R172117, a specific inhibitor of FDP synthase, and to sterol biosynthesis inhibitors such as flusilazol and fenpropimorph.Abbreviations: AP, Annick Petit; BAP, benzylaminopurine; CaMV, cauliflower mosaic virus; CTAB, cetyltrimethylammonium bromide; DMAEDP, dimethylamino ethyl diphosphate; DMADP, dimethylallyl diphosphate; DTT, dithiothreitol; ERG12, mevalonate kinase yeast gene; ERG20, FDP synthase yeast gene; FDP, farnesyl diphosphate; GGDP, geranylgeranyl diphosphate; GDP, geranyl diphosphate; IDP, isopentenyl diphosphate; LB, Luria Bertani; MS, Murashige and Skoog; NAA, Naphtaleneacetic acid; PVP, polyvinyl pyrrolidone; SBI, sterol biosynthesis inhibitor.     

Effects ofin Planta gamma-irradiation on growth, photosynthesis, and antioxidative capacity of red pepper (Capsicum annuum L.) plants

We investigated the effects of low-dose inplanta irradiation on red pepper plants treated with gamma rays of 2, 4, 8, and 16 Gy. Growth was stimulated at 2 and 4 Gy but inhibited at 8 and 16 Gy. Photochemical quenching (qP) increased slightly in all treatment groups for 1 d after irradiation (DAl), whereas non-photochemical quenching (NPQ) decreased more noticeably. These changes in qP and NPQ were transient and had almost recovered to the control level by 2 DAl. Although carotenoid pigments also fluctuated during the experimental period, chlorophylls were almost entirely insensitive to the gamma rays. Irradiation also partially protected leaves from a decrease in photochemical efficiency (Fv/Fm) under conditions of UV-B (2.2 W m^-2) and high light intensity (800 μmol m^-2 s^-1). This enhanced stress resistance could be partly explained by higher levels of SOD and APX activities, as well as ascorbate content. Our results demonstrate for the first time that the carotenoid pigments are the most radio-sensitive and fastest recovering compounds in plants, and that SOD, APX, and ascorbate are important inducible factors for improving stress resistance through the use ofin planta gamma-irradiation.     

Astaxanthin accumulation in Haematococcus requires a cytochrome P450 hydroxylase and an active synthesis of fatty acids

Astaxanthin accumulation by green microalgae is a natural phenomenon known as red snows and blood rains. The fact that astaxanthin synthesis requires oxygen, NADPH and Fe²⁺ led Cunningham and Gantt [Annu. Rev. Plant Physiol. Plant Mol. Biol. 49 (1998) 557–583] to propose that a cytochrome P450-dependent enzyme might be involved in the transformation of β-carotene to astaxanthin. In Haematococcus only esterified astaxanthin molecules accumulate, but it is not determined whether a fatty acid synthesis should occur simultaneously to allow pigment accumulation. The aim of this contribution was to answer these two questions using specific inhibitors of β-carotene (norflurazon) and fatty acid (cerulenin) synthesis, and of cytochrome P450 enzyme activity (ellipticine).     

VB1、VB12和VH对雨生红球藻生长及类胡萝卜素含量的影响

以淡水经济微藻雨生红球藻(Haematococcus pluvialis CH-1)为试验藻种,分别添加维生素B₁(VB₁)、B₁₂(VB₁₂)和维生素H(VH),每种维生素各分6个浓度梯度,测定了雨生红球藻的细胞密度、生物量、叶绿素a和类胡萝卜素含量等指标。结果表明,分别添加维生素B₁、B₁₂和H均显著促进了雨生红球藻细胞的生长。维生素B₁、B₁₂和H对雨生红球藻的最佳添加浓度分别为10mg·L^-1、50μg·L^-1和500μg·L^-1。在维生素B₁、B₁₂和H各自的最佳浓度处理下,雨生红球藻的细胞密度、生物量、叶绿素a和类胡萝卜素含量等4项指标均比对照有显著提高:维生素B₁处理分别提高了20.1%、14.6%、23.2%和21.3%;维生素B₁₂处理分别提高了29.5%、30.0%、28.0%和24.4%;维生素H处理分别提高了17.1%、29.2%、21.8%和10.1%。在雨生红球藻规模化生产的游动细胞培养阶段,适当地添加维生素B₁、B₁₂和H均能够有效地提高藻细胞密度、生物量、叶绿素a和类胡萝卜素含量。     

法夫酵母生物合成虾青素的研究

本文对法夫酵母是青素的生命合成进行了研究。实验结果表明,法夫酵母在ＹＥＰＤ培养基中生长时表现出二次生出现象,细胞内虾青素的合成是与细胞季开偶联的,在约６６ｈ达一在积累,３．４μｇ／ｍｌ。