Production of several isoforms of β-1,4-glucanase by the cyanolichen Peltigera canina

Lichen cellulase may participate in the degradation of the external substrata and/or modification of the photobiont cell wall. To promote a better understanding of the roles of cellulases in lichens, a cyanolichen was chosen because of the absence of cellulose in its symbionts. Freshly-collected thalli of Peltigera canina (L.) Wild, produce β-1,4-glucanase (EC 3.2.1.4, β-1,4-D-glucanohydrolase). This enzyme's activity was detected in the soluble and cell wall fractions and it was found to be secreted to the incubation medium when thalli were floated on water or on cellobiose. Several forms of the enzyme were detected by isoelectrofocusing. In preparative isoelectrofocusing, a single peak was obtained in each fraction, characterized by pls of 5.05, 5.25 and 4.75 in the soluble, cell wall and medium fractions, respectively. These differences were in agreement with the different pattern of bands obtained in slab-isoelectrofocusing, where the most acidic band (pl of 4.45) was present only in the soluble fraction and the band with higher pl (6.17) was more intense in the cell wall fraction. Since both symbionts in a cyanolichen lack cellulose, cellulases cannot participate in the modification of their cell wall; the presence of cellulase in Peltigera canina must therefore be related to the degradation of the tissues of the moss substratum.     

Field Measurements of Photosynthesis of Umbilicarious Lichens in Winter

The photosynthetic performance of Lasallia pustulata and Umbilicaria spodochroa was measured both in the field on granitic rock in southern Norway and in the laboratory under controlled conditions of light and temperature. In the field thallus temperatures varied between ? 2 and + 5 °C during the daylight period in January 1994. In situ water contents were between 50 and 400% d.wt. in L. pustulata and between 100 and 500% d.wt. in U. spodochroa. The lichens were active during the whole period of investigation. Photosynthetic rates reached 13.03 μmol CO₂ g Chl^?1 s^?1 in L. pustulata and 5.56 μmol CO₂ g Chl^?1 s^?1 in U. spodochroa. Ice formation on the thallus surface did not impede CO₂ exchange. Light was mainly the limiting factor, as could be confirmed by the laboratory experiments. In general, habitat conditions never provided optimum photosynthetic rates but photosynthetic carbon balance was positive during 4 of the 5 days investigated. The coldest day was photosynthetically almost as efficient as the warmest day during this period.     

Chemical variation within and between individuals of the lichenized ascomycete Tephromela atra

HPLC-analysis was used to determine the concentrations of the lichen compounds alectoronic acid (depsidon), -collatolic acid (depsidon) and atranorin (depsid) in the lichenized ascomycete Tephromela atra (syn. Lecanon atra) (Hudson) Hafeliner from limestone walls on the Baltic island of Öland, Sweden. In 24 individuals of T. atra sampled on a stone wall, the pre-reproductive and reproductive tissue did not differ in the concentrations of alectoronic acid, collatolic acid and atranorin. The concentrations of the three lichen compounds were inter-correlated in the reproductive tissue, but not in the pre-reproductive tissue. Single individuals of T. atra ranged in area covered from 10.1 to 147.4 cm² (mean: 38.5 cm²; N=24); 38.6% of this area was pre-reproductive tissue. However, the concentrations of the three lichen compounds were correlated neither with the total area covered by the lichen nor with the percentage of pre-reproductive tissue. This suggests that the concentrations of the lichen compounds do not change with increasing size (age) of the lichen. Analysis of specimens of T. atra from eight localities revealed a significant variation in lichen compounds (range between localities: alectoronic acid 0.60–3.26 μg/mg lichen dry weight (DW); collatolic acid 2.14–11.59 μg/mg lichen DW; atranorin 0.58–4.16 μg/mg lichen DW). The level of grazing observed in the lichens differed significantly among localities. However, no correlations between the concentrations of the three lichen compounds and the grazing damage to the lichens were found.     

Phenotypic variability and therapeutic implications of Candida species in patients with oral lichen planus

We investigated the prevalence and phenotypic variation of Candida species in oral lichen planus (OLP) and the therapeutic implications of our findings. Eighty patients with clinically and histopathologically confirmed cases of OLP (64 non-erosive, 16 erosive) and a control group of 80 healthy individuals with no predisposing factors for oral candidiasis were examined for evidence of Candida infection. Oral swabs and smears were obtained for cytology and culture. Identification, speciation and antifungal susceptibility tests of Candida isolates were performed using an automated microbial identification system. Fifty percent of erosive OLP cases, 28% of non-erosive cases and none of the controls showed evidence of Candida. Candida albicans was found predominantly in non-erosive OLP, while other Candida species were predominate in erosive OLP. Non-Candida albicans isolates (C. glabrata, C. krusei) were resistant to the commonly used antifungals, clotrimazole and fluconazole. Candida infection is common in cases of OLP. We recommend antifungal sensitivity testing prior to antifungal therapy for the erosive form of OLP.     

Graciliformin and its acetates in Cladonia graciliformis

From the lichen Cladonia graciliformis, three new pigments A, B and C were isolated along with bellidiflorin. Pigment A was an epimer of (+)-rugulosin diacetate and pigment B and C its corresponding deacetylated derivatives. Bellidiflorin is probably an iron complex compound of A. The chemical constituents of the mycobionts of Cl. graciliformis and Cl. bellidiflora were also studied.     

Caractérisation de la sticticine chez le lichen Lobaria laetevirens

Sticticin has been isolated from the thallus of Lobaria laetevirens. Its structure was determined by spectroscopic methods (NMR, MS) and comparison with a synthetic sample. It has been found in several species of the Stictaceae.     

Structure des acides isomuronique et neuropogolique,nouveaux acides aliphatiques du lichen Neuropogon trachycarpus

The structures of two new aliphatic acids, isomuronic and neuropogolic acid, from the lichen Neuropogon trachycarpus, were established by spectroscopic (MS, ¹H and ¹³C NMR) and chemical evidence. Circular dichroism data allowed the configuration of isomuronic acid to be assigned as 2R.     

Characterization of dopa betaine,tyrosine betaine and N-dimethyltyrosine from Lobaria laetevirens

DOPA betaine, tyrosine betaine and N-dimethyltyrosine were isolated from the lichen Lobaria laetevirens. Their structures were determined by ra     

Sterols of the mycobiont and phycobiont isolated from the litchen Xanthoria parietina

The mycobiont, Xanthoria parietina, and the phycobiont, Trebouxia decolorans, of the lichen X. parietina have been cultured separately and their sterols analysed. X. parietina contained ergosterol and lichesterol as the major constituents together with lower levels of three other C₂₈ sterols. Culture of the mycobiont in the presence of [CD₃]-methionine resulted in the incorporation of two deuterium atoms into the C-24 methyl group of these sterols demonstrating that a 24-methylene intermediate was produced as occurs in other fungi. The phycobiont, T. decolorans contained predominantly poriferasterol with lower levels of clionasterol, ergost-5-en-3β-ol, brassicasterol and cholesterol. Two other Trebouxia spp. (213/3 and 219/2) contained similar sterol mixtures.     

东北大小兴安岭地区梅衣科岛衣类和袋衣类地衣物种多样性

东北大小兴安岭地区是中国地衣的重要分布地之一, 蕴藏着丰富的地衣生物多样性。本研究基于259份标本馆馆藏及采集自东北大小兴安岭31个保护区的新鲜地衣标本, 结合形态学、解剖学、化学和DNA片段的综合分析, 鉴定并报道了该地区梅衣科岛衣类和袋衣类地衣11属31种, 包括环北极成分13种, 东亚成分11种, 世界广布成分3种, 中国特有成分3种, 欧亚成分1种。与之前记录和报道的该地区同类地衣物种组成进行对比, 结果显示隶属于2属的6种地衣在该地区未被重新发现, 表明这些地衣在该地区的分布可能大大萎缩乃至消失, 尤其是属于东亚成分的袋衣属2种: 粉袋衣(Hypogymnia farinacea)和日光山袋衣(H. nikkoensis), 自最初以东北大小兴安岭标本为凭证在中国报道分布后, 30余年未再新增任何标本信息, 日光山袋衣在近期中国大型真菌红色名录评估中被推测处于易危状态。