Influences of Nitrogen Sources on Usnic Acid Production in a Cultured Mycobiont of the Lichen Usnea hirta (L.) Wigg.

Effects of the nitrogen sources in the medium for the production of secondary metabolites in lichens were examined. The usnic acid production by a mycobiont of the lichen Usnea hirta was higher in the liquid medium containing ammonium and nitrate ions than in those containing amino acids.     

喇叭石蕊共生菌藻液体培养的研究

对喇叭石蕊共生菌、藻液体培养条件进行了研究。结果表明:共生菌生长在以40g/L肌醇为碳源、2g/LL-谷氨酰胺为氮源、起始pH值为7.0的LB液体培养基中,培养温度为20℃时表现最佳。其共生藻的生长在以160g/L葡萄糖为碳源、1.75g/LNaNO3为氮源、起始pH值为5.0的BBM液体培养基中,培养温度为20℃时表现最佳。     

漠黄梅共生菌藻宏基因组文库的构建

为了从耐旱地衣漠黄梅的共生菌藻基因组中筛选功能基因,并为蛋白质类药物的基因筛选提供平台,采用改进的CTAB方法提取其总DNA,用Sau3AⅠ限制性内切酶部分酶切基因组DNA,以质粒pUC19为载体,转入大肠杆菌DH5α中,构建了漠黄梅共生菌藻的宏基因组文库。该文库包含了4.8×105个重组子,插入片段的平均大小为4kb,覆盖漠黄梅菌藻的整个基因组4次。     

Photobiont Selectivity and Interspecific Interactions in Lichen Communities. I. Culture Experiments with the Mycobiont Fulgensia bracteata

Abstract: Lichen communities are characterised by interspecific interactions that not only include interactions between different lichen species but also between the symbionts within a single lichen species. The community “Bunte Erdflechtengesellschaft”, growing on weathered calciferous rocks known as Gravel Alvar on Gotland (Baltic Sea, Sweden), shows a high complexity of inter‐ and intraspecific interactions, including Fulgensia bracteata, F. fulgens, Toninia sedifolia, Squamarina cartilaginea, Psora decipiens and Lecidea lurida. F. bracteata and F. fulgens are the dominant species of this community, showing a tendency to overgrow the other species involved and even parasitic behaviour. Culture experiments have been performed to investigate the selectivity of the mycobiont of F. bracteata towards a variety of potential photobionts. The results provide evidence for the selectivity of the mycobiont and varying compatibility of the respective symbionts that can be interpreted as a cascade of interdependent processes of specific and non‐specific reactions of the symbionts involved.     

Comparative studies on the polysaccharides of Cladonia alpestris (reindeer moss), Cladonia confusa,and Cladonia amaurocraea

The chemical structures of polysaccharide components of three species of the lichen genus Cladonia were compared. C. alpestris and C. confusa are similar in overall growth appearance despite different habitats, and each contains traces of water-insoluble nigeran. The residual lichens gave almost pure d-galacto-d-mannans isolated via insoluble Cu complexes formed with Fehling solution. They were not identical but structurally related having (1→6)-linked α-d-mannopyranosyl main-chains substituted in different patterns by β-d-galacto- and α-d-mannopyranosyl groups. Supernatant solutions of the Fehling-solution precipitation contained high proportions of β-d-galactofuranosyl residues. The polysaccharide of C. alpestris contained consecutive (1→2)-linked α-d-mannopyranosyl units substituted in the 6-position by β-d-galactofuranose, whereas that of C. confusa was a d-galactan with both pyranosyl and furanosyl forms. The d-glucan component of C. amaurocraea was isolated together with d-galacto-d-mannan as insoluble Cu complexes. The former was isolated in good yield and proved to be water-insoluble pustulan. The galactomannan had the same overall structure as those of C. alpestris and C. confusa, but showed differences according to the ¹³C-n.m.r. spectra.     

Homoheveadride,a cyclononadiene bis-anhydride from Cladonia polycarpoides

The isolation of a novel cyclononadiene bis-anhydride, homoheveadride (8-butyl-7-pentylcyclonona-l,5-diene-1,2,5,6-tetracarboxylic dianhydride) from the lichen Cladonia polycarpoides Nyl. in Zwackh is reported.     

Cladonia monomorpha,a neglected cup lichen from Europe

Abstract:Cladonia monomorpha is recognized as a distinct species in the Cladonia pyxidata group. It is characterized by thallus lobes with narrowly recurved margins, by the presence of discoid, bullate plates on the podetial surface and by long and sometimes branched proliferations of the scyphus margins supporting the apothecium discs. It is described from the Netherlands, where it occurs in acid inland sand dune areas with the highest terrestrial lichen diversity. It appears to be widespread in Europe on siliceous rock and acid sand.     

Phylogeny of bipolar Cladonia arbuscula and Cladonia mitis (Lecanorales,Euascomycetes)

Phylogenetic relationships and levels of geographic differentiation of two closely related bipolar taxa, Cladonia arbuscula and Cladonia mitis, were cladistically examined with ITS regions, SSU rDNA introns, partial beta-tubulin, and partial glyceraldehyde 3-phosphate dehydrogenase (GAPDH) genes. In the combined analysis of the four genes, C. arbuscula was paraphyletic, while C. mitis, nested within C. arbuscula, formed a strongly supported monophyletic group. C. arbuscula samples were divided into three separate clades: "arbuscula I," appearing as basal to the other ingroup taxa, "arbuscula II," and "arbuscula III" (the latter represented by only one specimen), which were not correlated with any morphological trait. Only C. mitis specimens formed a morphologically and chemically distinct group. None of the main clades was correlated with geographic origin. The separate analyses were poorly resolved, and in most cases samples from "arbuscula I," "arbuscula II," and "arbuscula III" clades were intermixed. An incongruence test revealed conflict among the four gene regions in almost all cases. Only ITS regions and introns were not significantly incongruent, suggesting lack of recombination within the ribosomal DNA locus. Incomplete lineage sorting and recombination were considered to be the main reasons accounting for the incongruencies. The high proportion of shared polymorphisms between the "arbuscula I" and "arbuscula II" clades, especially found from the beta-tubulin gene and from the ITS regions, and the lack of corroborating morphological characters both indicate a short history of reproductive isolation among the groups. The lack of genetic differentiation among the northern and southern samples within the main clades indicates a relatively recent gene flow, which may have resulted from migrations during the Pleistocene glaciations or from more recent long-distance dispersal.     

Contribution to the Cladonia mycota of Greece, including Cladonia graeca sp. nov.

From mid-elevation pine forest on the Aegean Sea island of Thasos 8 additional Cladonia species for the lichen mycota of Greece are reported.Most have a wide distribution in Europe and reach their southern limit in Greece.From schistose rock in the same area and on Evvia a new species is described,Cladonia graeca,which is probably related to C.macrophylla and C.decorticata but contains fumarprotocetraric acid instead of psoromic or perlatolic acid.     

Cladonia krogiana,a new xanthone-containing species from Norway

Abstract:The new lichen species Cladonia krogiana is described from eight localities in SE Norway. It resembles C. polycarpoides morphologically, but differs in containing barbatic acid and chlorovinetorin.     

Cladonia petrophila,a new species from eastern North America

Cladonia petrophila, an overlooked, usually sterile species, morphologically similar toC. apodocarpa andC. caespiticia, is described as new on the basis of its distinctive chemistry, perlatolic and fumarprotocetraric acids, and habitat preference for moist non-calcareous rock.     

Cladonia azorica in the British Isles

Abstract:Cladonia azorica is widespread in western Great Britain, mainly as the grey colour-form lacking usnic acid. Cladonia azorica is distinguished from the related species C. portentosa and C. mediterranea by the presence of fumarprotocetraric acid, and from C. ciliata by a number of characters including the presence of perlatolic acid. The structure of the pycnidial wall may have some taxonomic significance in Cladonia subgenus Cladina.     

Cladonia singhii and other new reports of Cladonia from the Eastern Himalayan Region of India

Abstract:A new species, Cladonia singhii Ahti & Dixit (type from the state of Arunachal Pradesh), is described. A further seven Cladonia species, C. corniculata, C. kanewskii, C. laii, C. luteoalba, C. mauritiana, C. mongolica and C. rei, are reported as new to the recent checklist of lichens of the Indian subcontinent. The presence of C. cartilaginea in India is confirmed.     

CCS5, a Thioredoxin-like Protein Involved in the Assembly of Plastid c-Type Cytochromes

The c-type cytochromes are metalloproteins with a heme molecule covalently linked to the sulfhydryls of a CXXCH heme-binding site. In plastids, at least six assembly factors are required for heme attachment to the apo-forms of cytochrome f and cytochrome c₆ in the thylakoid lumen. CCS5, controlling plastid cytochrome c assembly, was identified through insertional mutagenesis in the unicellular green alga Chlamydomonas reinhardtii. The complementing gene encodes a protein with similarity to Arabidopsis thaliana HCF164, which is a thylakoid membrane-anchored protein with a lumen-facing thioredoxin-like domain. HCF164 is required for cytochrome b₆f biogenesis, but its activity and site of action in the assembly process has so far remained undeciphered. We show that CCS5 is a component of a trans-thylakoid redox pathway and operates by reducing the CXXCH heme-binding site of apocytochrome c prior to the heme ligation reaction. The proposal is based on the following findings: 1) the ccs5 mutant is rescued by exogenous thiols; 2) CCS5 interacts with apocytochrome f and c₆ in a yeast two-hybrid assay; and 3) recombinant CCS5 is able to reduce a disulfide in the CXXCH heme-binding site of apocytochrome f.     

Cladonia (sect. Cocciferae) norvegica, a new lichen species

Cladonia (sect. Cocciferae , subsect. Ochroleucae) norvegica T0nsb. & Holien sp. nov., is closely related to C. bacilliformis (Nyl.) DT. & Sarnth. but is morphologically, chemically, and ecologically distinct. Superficially it may resemble C. (sect. Cladonia) coniocraea auct., which is often growing with it. C. norvegica is known from Norway only.     

Novel structures in galactoglucomannans of the lichens Cladonia substellata and Cladonia ibitipocae: significance as chemotypes.

The galactoglucomannans of two species of the lichen genus Cladonia, C. substellata and C. ibitipocae, were compared. They were homogeneous on gel-filtration chromatography and structurally related, having (1-->6)-linked alpha-D-mannopyranosyl main-chains, but were substituted in different patterns by alpha- and beta-D-galacto-, beta-D-gluco- and alpha-D-mannopyranosyl groups. The C-1 portions of their 13C-NMR spectra are typical of the lichen species and indicate differences between the two polysaccharides. Partial acetolysis of the galactoglucomannan from C. substellata gave rise to oligosaccharides and three were identified, namely alpha-D-Manp-(1-->3)-alpha beta-D-Galp, alpha-D-Manp-(1-->2)-alpha beta-D-Manp and alpha-D-Manp-(1-->2)-[beta-D-Glcp-(1-->4)]-alpha beta-D-Manp, whereas only the latter two were obtained from that of C ibitipocae. Methylation and Smith degradation data confirmed these results. Whereas the mannobiose represents a common structure in lichen heteropolysaccharides, it is the first time that the other oligosaccharides have been isolated from those of lichens.     

Breeding systems in the lichen-forming fungal genus Cladonia

The breeding systems of three species of the lichen-forming fungal genus Cladonia were investigated. Cladonia floerkeana, Cladonia galindezii, and Cladonia portentosa were selected due to their contrasting ecologies and reproductive strategies, and because they belong to the Lecanorales, the major lichen-forming order. Sibling single-spore progeny were collected from apothecia and used to establish axenic cultures. Two experimental approaches were used to determine breeding systems. First, RAPD-PCR and AFLP fingerprinting revealed that spores from the same apothecium were not genetically uniform, indicating heterothallism in each of these species. Second, segregation of a MAT-2 mating-type gene was assessed using degenerate PCR primers designed to amplify the high-mobility group region. A MAT-2 gene occurred in 40-60% of progeny, consistent with a heterothallic breeding system. The PCR product from C. galindezii was cloned and sequenced, and confirmed to have the characteristic motifs of a MAT-2 HMG gene. This is thought to be the first report of the use of segregation of a mating-type gene among ascospore progeny to determine the breeding system of a fungal species. The ecological significance of the results is discussed.