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Primary charge separation in Photosystem II 总被引:3,自引:3,他引:0
In this Minireview, we discuss a number of issues on the primary photosynthetic reactions of the green plant Photosystem II.
We discuss the origin of the 683 and 679 nm absorption bands of the PS II RC complex and suggest that these forms may reflect
the single-site spectrum with dominant contributions from the zero-phonon line and a pronounced ∼80 cm−1 phonon side band, respectively. The couplings between the six central RC chlorins are probably very similar and, therefore,
a `multimer' model arises in which there is no `special pair' and in which for each realization of the disorder the excitation
may be dynamically localized on basically any combination of neighbouring chlorins. The key features of our model for the
primary reactions in PS II include ultrafast (<500 fs) energy transfer processes within the multimer, `slow' (∼20 ps) energy
transfer processes from peripheral RC chlorophylls to the RC multimer, ultrafast charge separation (<500 fs) with a low yield
starting from the singlet-excited `accessory' chlorophyll of the active branch, cation transfer from this `accessory' chlorophyll
to a `special pair' chlorophyll and/or charge separation starting from this `special pair' chlorophyll (∼8 ps), and slow relaxation
(∼50 ps) of the radical pair by conformational changes of the protein. The charge separation in the PS II RC can probably
not be described as a simple trap-limited or diffusion-limited process, while for the PS II core and larger complexes the
transfer of the excitation energy to the PS II RC may be rate limiting.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
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Keszthelyi L 《Biophysical chemistry》1988,29(1-2):127-136
The bacteriorhodopsin protein (bR) in the cell membrane of Halobacterium halobium is a light driven proton pump. Many details are known about its structure and the molecular mechanism of proton translocation. The events may be characterized by: (1) the changes in light absorption after photon excitation (the photocycle); (2) the charge motion cycle inside the protein: the steps taken by the proton during translocation; (3) the retinal cycle. changes in isomerization and protonation; and (4) the opsin cycle: alterations of protonation of different amino acids in the apoprotein. From a review of existing data a more or less concise picture of the parallelism of the above four cycles emerges, which may be valuable as a model for understanding other types of molecular pumps. 相似文献
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为了解黄檗鞘锈菌Coleosporium phellodendri担子发育及担孢子萌发的细胞学变化,采用光学显微镜观察了冬孢子萌发、担子发育及担孢子萌发过程,并利用苏木精染色法对冬孢子萌发过程中细胞核的变化进行了研究。结果表明:未成熟的冬孢子含有两个细胞核,成熟时冬孢子伸长,两个细胞核融合成为1个核;冬孢子萌发时,中间形成一隔膜,将冬孢子分成两部分,上部分含金黄色的原生质体,下部呈透明的柄状结构;上部分发育形成4个细胞的内担子,然后发育形成担孢子。担孢子萌发时,产生1个芽管,顶端形成外观上与担孢子形态大小基本一致的次生孢子。次生孢子萌发产生芽管,形成菌丝。有极个别的次生孢子可再次形成次生孢子。冬孢子和担孢子在5–25℃温度范围内均能萌发,其中以15–25℃为适宜萌发的温度范围。 相似文献
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Reconstructing the evolution of agarics from nuclear gene sequences and basidiospore ultrastructure 总被引:1,自引:0,他引:1
Sigisfredo Garnica Michael Weiss Grit Walther Franz Oberwinkler 《Mycological Research》2007,111(9):1019-1029
Traditional classifications of agaric fungi involve gross morphology of their fruit bodies and meiospore print-colour. However, the phylogeny of these fungi and the evolution of their morphological and ecological traits are poorly understood. Phylogenetic analyses have already demonstrated that characters used in traditional classifications of basidiomycetes may be heavily affected by homoplasy, and that non-gilled taxa evolved within the agarics several times. By integrating molecular phylogenetic analyses including domains D1–D3 and D7–D8 of nucLSU rDNA and domains A–C of the RPB1 gene with morphological and chemical data from representative species of 88 genera, we were able to resolve higher groups of agarics. We found that the species with thick-walled and pigmented basidiospores constitute a derived group, and hypothesize that this specific combination of characters represents an evolutionary advantage by increasing the tolerance of the basidiospores to dehydration and solar radiation and so opened up new ecological niches, e.g. the colonization of dung substrates by enabling basidiospores to survive gut passages through herbivores. Our results confirm the validity of basidiospore morphology as a phylogenetic marker in the agarics. 相似文献
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运用建立的高效液相色谱条件,首次实现在完成灵芝孢子粉中麦角甾醇含量测定的同时,对灵芝孢子粉中脂溶性成分的指纹图谱进行研究。结果表明,该方法测定麦角甾醇准确、稳定、特异性好,脂溶性成分指纹图谱基线平直、色谱峰丰富且具备较好的分离度,该方法适合在分析测定灵芝孢子粉中麦角甾醇(282nm)含量的同时,对其脂溶性成分(245nm)的指纹图谱进行分析,为整体评价灵芝孢子粉及其产品的质量提供依据。运用建立的方法对收集的各孢子粉样品进行分析,表明破壁与否及破壁时间长短对灵芝孢子粉中麦角甾醇及脂溶性成分的溶出有显著的影响,实验认为最佳的破壁时间为20-30min;低温冻藏可以有效地保护样品中的成分;随着产粉时间的延长,孢子粉中麦角甾醇的含量变化不大,脂溶性成分总体上有所增加;不同原料来源孢子粉中麦角甾醇的含量和脂溶性成分指纹图谱的差异都很大,且麦角甾醇的含量与指纹图谱色谱峰的丰富程度没有一定的相关性,因此不能仅以麦角甾醇的含量来表征灵芝孢子粉的质量,二者的综合分析对灵芝孢子粉质量的评价才更有意义。 相似文献
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The plant and microbial peroxidase superfamily encompasses three classes of related protein families. Class I includes intracellular
peroxidases of prokaryotic origin, class II includes secretory fungal peroxidases, including the lignin degrading enzymes
manganese peroxidase (MnP), lignin peroxidase (LiP), and versatile peroxidase (VP), and class III includes the secretory plant
peroxidases. Here, we present phylogenetic analyses using maximum parsimony and Bayesian methods that address the origin and
diversification of class II peroxidases. Higher-level analyses used published full-length sequences from all members of the
plant and microbial peroxidase superfamily, while lower-level analyses used class II sequences only, including 43 new sequences
generated from Agaricomycetes (mushroom-forming fungi and relatives). The distribution of confirmed and proposed catalytic
sites for manganese and aromatic compounds in class II peroxidases, including residues supposedly involved in three different
long range electron transfer pathways, was interpreted in the context of phylogenies from the lower-level analyses. The higher-level
analyses suggest that class II sequences constitute a monophyletic gene family within the plant and microbial peroxidase superfamily,
and that they have diversified extensively in the basidiomycetes. Peroxidases of unknown function from the ascomycete Magnaporthe grisea were found to be the closest relatives of class II sequences and were selected to root class II sequences in the lower-level
analyses. LiPs evidently arose only once in the Polyporales, which harbors many white-rot taxa, whereas MnPs and VPs are more
widespread and may have multiple origins. Our study includes the first reports of partial sequences for MnPs in the Hymenochaetales
and Corticiales. 相似文献
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The production of NADP-dependent glutamate dehydrogenase was initiated at the stage of first meiotic prophase in pileus cells but not in stipe cells of dikaryotic and monokaryotic fruiting bodies in Coprinus macrorhizus. The production of chitinase and glucanases assayed with laminarin and lichenan was observed after the completion of meiosis only in pileus cells. The light conditions that were effective for the delay or inhibition of cellular events in the pileus cells were also effective for the delay or inhibition of enzyme production. But all sporeless mutants tested, which were defective at the various stages of basidiospore formation, produced the normal levels of these enzymes. The results indicate that the sequential production of enzymes and cellular events leading to basidiospore formation in pileus cells are independent from each other.Abbreviation GDHNADP
NADP-dependent glutamate dehydrogenase 相似文献
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Isotopic studies of carbohydrate metabolism during basidiospore germination in Schizophyllum commune
Summary The metabolism and fate of specifically labeled glucose-14C were compared to mannitol-l-14C and arabitol-l-14C during basidiospore germination of Schizophyllum commune on glucose-asparagine minimal broth. Glucose-l-14C metabolism led to more 14CO2 evolution than glucose-6-14C in spores and the former activity increased upon germination. Liberation of 14CO2 from glucose-3,4-14C increased at 8 h to 12 h of germination and exceeded the amount of radioactive 14CO2 released from glucose-1-14C. The 14CO2 released from glucose-2-14C increased continually during germination while only minor changes in 14CO2 evolution occurred with glucose-6-14C. Unlabeled ethanol (0.25 M) inhibited 14CO2 evolution with glucose-3,4-14C and ungerminated spores and this inhibition disappeared upon germination.More 14CO2 was evolved from labeled glucose during germination and less radioactivity became associated with cellular material. Of the latter, alcohol-soluble extracts of spores or germlings contained mainly radioactive trehalose, less mannitol and little or no labeled arabitol, and this decreased upon germination. Germlings also converted more radioactive glucose-14C into KOH-insoluble material and KOH-soluble components. Spores or germlings converted arabitol-1-14C primarily into trehalose and this was not the case for mannitol-1-14C. 相似文献
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Konomi Yanaga Nitaro Maekawa Norihiro Shimomura Yasuhito Ishigaki Yuka Nakamura Tsutomu Takegami Naohisa Tomosugi Shichiro Miyazawa Susumu Kuwabata 《Mycological Progress》2012,11(1):343-347
An ionic liquid (IL) is a kind of salt that stays in a molten state even at room temperature. Since ILs do not vaporize even
under vacuum conditions and show high ionic conductivity, they can be used in scanning electron microscopy (SEM) studies.
The ultrastructural features of basidiospore ornamentation are considered to be important in the delimitation of taxa for
fungi. In the present study, we carried out SEM observations on basidiospores that were subjected to an IL treatment, and
evaluated the usefulness of this method in comparison with a conventional preparation method in which dehydrating, drying
and platinum (Pt) coating were used. Using the conventional method, a considerable number of basidiospores was lost from the
gill tissues; however, using the IL method, the decrease in basidiospores was extremely small. No significant differences
in ultrastructural morphology or basidiospore size were found between Pt-coated basidiospores and IL-treated ones. SEM images
of Pt-coated basidiospores tended to have higher contrast than those of IL-treated ones. Charging effects were observed with
Pt-coated basidiospores, especially at the tips of the ornaments, whereas no such effects occurred for the IL-treated ones.
In addition, small crinkles were observed in the Pt-coated basidiospores, but not in the IL-treated ones. These results suggest
that the IL method is useful for fungal taxonomic studies. 相似文献
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Summary The cytology of teliospore germination and basidiospore formation inUromyces appendiculatus var.appendiculatus was characterized with light and fluoroscence microscopy. Meiosis of the diploid nucleus occurred in the metabasidium. The four haploid daughter nuclei migrated into the basidiospore initials where they underwent a post meiotic mitosis. Each basidiospore was delimited from the meatabasidium by a septum at the apex of the sterigma. Seventy-five percent of mature basidiospores were binucleate, 24.5% uninucleate, and 0.5% trinucleate. Mature, released basidiospores measured 16×9 m, were smooth-surfaced, and reniform to ovate-elliptical in shape.This study represents portion of a dissertation submitted by the senior author to the Faculty of Biology of the University of Constance in March, 1983, in partial fulfillment of the requirements for the degree of Doctor of Natural Sciences (Dr. rer. nat.). 相似文献
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Summary The kinetics, nutritional requirements and inhibitor properties of basidiospore germination in the wood-rotting mushroom Schizophyllum commune were investigated. Measurements of changes in absorbancy and dry weight showed a lag period of approximately 15–20 hrs, followed by an abrupt increase in the rate of both processes. Individual basidiospore elongation also showed a lag phase and population changes were heterogenous in this regard.Carbohydrates active for basidiospore germination were grouped into four categories. Those sugars active between 15 and 20 hrs included glycogen, turanose, cellobiose, maltose, sucrose, glucose, fructose, mannose, galactose and xylose. Several sugar alcohols were only active between 30 and 60 hrs incubation and these included mannitol, sorbitol, ribitol, xylitol, arabitol, erythritol and glycerol. A third category of carbohydrates active for germination required prolonged incubation between 30 hrs and 7 days and included lactose, sorbose, raffinose, melezitose, trehalose, ribose and melibiose. Compounds without activity after 7 days included galactitol, inositol, acetate, succinate, gluconate, citrate, fumarate, rhamnose, fucose and inulin.Nitrogen sources active in basidiospore germination included complex organic nitrogenous substrates, asparagine, glutamine, arginine, urea and various ammonium salts.Germination was inhibited by cycloheximide, l-ethionine, p-fluoro-dl-phenylalanine, sodium azide, 2,4-dinitrophenol, phenylmercuric acetate and 2-deoxy-d-glucose. Alkali as a trapping agent arrested germination in glucose-(NH4)2SO4 medium but was without ill-effect in glucose peptone broth. 相似文献
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Summary Uptake and respiration of radioactive glucose, mannitol and arabitol were studied during basidiospore germination of the woodrotting mushroomSchizophyllum commune. Glucose uptake was rapid and immediate, depressed at 4° C and unaffected by the protein synthesis antagonist cycloheximide. In contrast, uptake of either mannitol or arabitol exhibited a lag phase while the induction of this process was sensitive to cycloheximide. Prior incubation of basidiospores in unlabelled mannitol induced uptake processes for either labelled mannitol or arabitol. Respiratory rates for either arabitol or mannitol increased markedly upon germination in glucose-asparagine minimal culture medium.This research was supported by Public Health Service Grant AI-04603-09 to Donald J. Niederpruem. 相似文献
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D. Leuschner 《Biometrical journal. Biometrische Zeitschrift》1981,23(6):611-620
Thermodynamic taxonomy (ThT) is established from both a theoretical and pragmatical point of view. An application of thermodynamic taxonomy is given. 相似文献
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K. Gull 《Archives of microbiology》1981,128(4):403-406
The meiotic spindles of Phallus impudicus had a similar ultrastructure to those seen in other basidiomycetes. After meiosis the basidal apex differentiated to form a number of broadly based protuberances which subsequently developed into basidiospores (up to 9 per basidium). The nuclei then underwent a post-meiotic mitosis within the cytoplasm of each basidiospore. After this mitosis one nucleus remained in the basidiospore and a complete septum developed at the base. The significance of this arrangement of meiosis, spore production and post-meiotic mitosis is discussed with respect to the taxonomy and life cycle of this unusual basidiomycete. 相似文献
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Malte C. Ebach Antonio G. Valdecasas Quentin D. Wheeler 《Cladistics : the international journal of the Willi Hennig Society》2011,27(5):550-557
There has been much discussion of the “taxonomic impediment”. This phrase confuses two kinds of impediment: an impediment to end users imposed by lack of reliable information; and impediments to taxonomy itself, which vary from insufficient funding to low citation rates of taxonomic monographs. In order to resolve both these types of impediment, taxonomy needs to be revitalized through funding and training taxonomists, as well as investing in taxonomic revisions and monographs rather than technological surrogates such as DNA barcoding.© The Willi Hennig Society 2011. 相似文献