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.     

Nitrogen and carbon isotope variability in the green‐algal lichen Xanthoria parietina and their implications on mycobiont–photobiont interactions

Stable isotope patterns in lichens are known to vary largely, but effects of substrate on carbon and nitrogen stable isotope signatures of lichens were previously not investigated systematically. N and C contents and stable isotope (δ¹⁵N, δ¹³C) patterns have been measured in 92 lichen specimens of Xanthoria parietina from southern Bavaria growing on different substrates (bark and stone). Photobiont and mycobiont were isolated from selected populations and isotopically analyzed. Molecular investigations of the internal transcribed spacer of the nuclear ribosomal DNA (ITS nrDNA) region have been conducted on a subset of the specimens of X. parietina. Phylogenetic analysis showed no correlation between the symbionts X. parietina and Trebouxia decolorans and the substrate, isotope composition, or geographic origin. Instead specimens grown on organic substrate significantly differ in isotope values from those on minerogenic substrate. This study documents that the lichens growing on bark use additional or different N sources than the lichens growing on stone. δ¹⁵N variation of X. parietina apparently is controlled predominantly by the mass fraction of the mycobiont and its nitrogen isotope composition. In contrast with mycobionts, photobionts of X. parietina are much more ¹⁵N‐depleted and show less isotopic variability than mycobionts, probably indicating a mycobiont‐independent nitrogen acquisition by uptake of atmospheric ammonia.     

A cyanolichen from the Lower Devonian Rhynie chert

The 400 million-year-old Rhynie chert has provided a wealth of information about various types of fungal interactions that existed in this Early Devonian paleoecosystem. In this paper we report the first unequivocal evidence of a lichen symbiosis from the Rhynie chert. Specimens of a new genus, Winfrenatia, consist of a thallus of superimposed layers of aseptate hyphae and, on the upper surface, numerous uniform depressions. Extending into the base of each depression are hyphae that form a three-dimensional netlike structure. Enclosed within each of the net spaces is a coccoid cyanobacterium, each cell of which is surrounded by a thick sheath. These photobiont cells divide in three planes, resulting in cell clusters of up to perhaps 64 individuals. The photobiont is parasitized by the fungus in the base of each net as new cyanobacterial cells are formed distally. Reproduction is by endospores and soredia. Affinities of the mycobiont appear closest to members of the Zygomycetes, while the photobiont is most similar to coccoid cyanobacteria of the Gloeocapsa and Chroococcidiopsis types. We speculate that this cyanobacterial symbiosis was well adapted to exploit and colonize new ecological niches, especially in the periodically desiccated environment postulated for the Rhynie chert paleoecosystem.     

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.     

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.     

喇叭石蕊共生菌藻液体培养的研究(英文)

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。     

三种石黄衣的共生菌化学多样性及其系统生物学意义

本文对丽石黄衣(Xanthoria elegans)、中国石黄衣(X. mandschurica)和刺盘石黄衣(X. alfredi)的共生菌,尤其是刺盘石黄衣共生菌的分离培养物进行了首次研究。对于上述三种地衣体及其共生菌的化学物质进行了比较分析。研究与分析结果表明,三种石黄衣地衣体化学物质,即蒽醌类化合物完全一致。此外, Lindblom从15种北美石黄衣地衣体中检测出了彼此一致的5种蒽醌类化合物。因此,该作者认为石黄衣属的蒽醌类化合物不具有种级分类学意义。本文的实验结果也证实了这一观点。但是,本文对于通过子囊孢子释放法获得的中国三种石黄衣共生菌的化学物质进行了检测和分析,其结果呈现出比较丰富的多样性。其中刺盘石黄衣共生菌化学物质与丽石黄衣和中国石黄衣共生菌所含的化学物质存在明显差异。因而,刺盘石黄衣共生菌化学物质在该种地衣的鉴定中具有重要的参考价值。 此外,文章亦检测和分析了丽石黄衣的10株共生菌化学物质。供试菌株均在相同培养条件和培养时间下获得。其化学物质的TLC图谱,除Nos. 5, 7, 及10稍有差异外,几乎完全一致。由此看来,它们稳定性也是比较明显的。 上述结果提示我们,在地衣系统生物学研究中,除了对于地衣体化学物质进行常规检测与分析之外,对于分离培养的各种地衣共生真菌化学物质的检测与分     

Simple method for fractionation of <Emphasis Type="Italic">Parmelia sulcata</Emphasis> lichen thalli

Three fractions were isolated from Parmelia sulcata lichen thalli: mycobiont-enriched fraction, highly purified preparation of Trebouxia sp. alga, and a photobiont-enriched fraction, in which the fungal component and symbiotic relations between the bionts were retained. The ratio between the fungal and algal components in all fractions was estimated from the photosynthesis/respiration and chlorophyll/dry weight ratios. Simple methods for lichen thallus fractionation are suggested to study symbiotic relationships of bionts.Translated from Fiziologiya Rastenii, Vol. 52, No. 2, 2005, pp. 306–310.Original Russian Text Copyright © 2005 by Maslov, Pavlova.This revised version was published online in April 2005 with a corrected cover date.