Can Antarctic lichens acclimatize to changes in temperature?

The Antarctic Peninsula, a tundra biome dominated by lichens and bryophytes, is an ecozone undergoing rapid temperature shifts. Such changes may demand a high physiological plasticity of the local lichen species to maintain their role as key drivers in this pristine habitat. This study examines the response of net photosynthesis and respiration to increasing temperatures for three Antarctic lichen species with different ecological response amplitudes. We hypothesize that negative effects caused by increased temperatures can be mitigated by thermal acclimation of respiration and/or photosynthesis. The fully controlled growth chamber experiment simulated intermediate and extreme temperature increases over the time course of 6 weeks. Results showed that, in contrast to our hypothesis, none of the species was able to down‐regulate temperature‐driven respiratory losses through thermal acclimation of respiration. Instead, severe effects on photobiont vitality demonstrated that temperatures around 15°C mark the upper limit for the two species restricted to the Antarctic, and when mycobiont demands exceeded the photobiont capacity they could not survive within the lichen thallus. In contrast, the widespread lichen species was able to recover its homoeostasis by rapidly increasing net photosynthesis. We conclude that to understand the complete lichen response, acclimation processes of both symbionts, the photo‐ and the mycobiont, have to be evaluated separately. As a result, we postulate that any acclimation processes in lichen are species‐specific. This, together with the high degree of response variability and sensitivity to temperature in different species that co‐occur spatially close, complicates any predictions regarding future community composition in the Antarctic. Nevertheless, our results suggest that species with a broad ecological amplitude may be favoured with on‐going changes in temperature.     

Alteration of salivary glycopatterns in oral lichen planus

Background: Oral lichen planus (OLP) is one of the most common oral mucosal lesions affecting 0.5–2% of the adult population. It is difficult to distinguish between OLP and other oral mucosal diseases. Structural changes in the glycans of saliva proteins might be reliable indicators of OLP. However, little is known about the alteration of salivary glycopatterns during OLP.

Objective: We aimed to investigate the alterations of salivary protein glycosylation related to OLP.

Material and methods: Twenty-eight patients with OLP and 30 age- and sex-matched healthy volunteers (HVs) were enrolled in the test group to probe the difference of salivary glycopatterns using lectin microarrays. The lectin blotting were further utilized to validate the expression of certain glycans.

Results: The glycoproteins recognized by three lectins [Aleuria aurantia lectin (AAL); Phytolacca americana (PWM); Phaseolus vulgaris agglutinin (E?+?L), (PHA-E?+?L)] were mainly increasing in the saliva of OLP. Meanwhile, these glycoproteins also exhibited significant age-associated alterations.

Conclusions: This study provided a new basic insight into salivary glycopatterns in OLP and helped to develop new potential biomarkers for diagnosis of OLP.     

DIATOMS LIVING INSIDE THE THALLUS OF THE GREEN ALGAL LICHEN COENOGONIUM LINKII IN NEOTROPICAL LOWLAND RAIN FORESTS1

Coenogonium linkii Ehrenb. is a very common filamentous lichen, growing on stems, hanging roots, and lianas in the understory of neotropical lowland rain forests. We investigated several thalli of this species from locations in Panama and French Guiana. All thalli were inhabited by various species of terrestrial diatoms, which were found between the thallus filaments on extracellular material of the mycobiont. We identified 18 species of diatoms belonging to nine genera: Diadesmis, Eunotia, Hantzschia, Luticola, Melosira, Nitzschia, Orthoseira, Pinnularia, and Stauroneis. The potential benefits both diatoms and lichens could derive from symbiosis in relation to water, irradiance, and nitrogen availability are discussed.     

Potential and pitfalls of eukaryotic metagenome skimming: a test case for lichens

Whole‐genome shotgun sequencing of multispecies communities using only a single library layout is commonly used to assess taxonomic and functional diversity of microbial assemblages. Here, we investigate to what extent such metagenome skimming approaches are applicable for in‐depth genomic characterizations of eukaryotic communities, for example lichens. We address how to best assemble a particular eukaryotic metagenome skimming data, what pitfalls can occur, and what genome quality can be expected from these data. To facilitate a project‐specific benchmarking, we introduce the concept of twin sets, simulated data resembling the outcome of a particular metagenome sequencing study. We show that the quality of genome reconstructions depends essentially on assembler choice. Individual tools, including the metagenome assemblers Omega and MetaVelvet, are surprisingly sensitive to low and uneven coverages. In combination with the routine of assembly parameter choice to optimize the assembly N50 size, these tools can preclude an entire genome from the assembly. In contrast, MIRA, an all‐purpose overlap assembler, and SPAdes, a multisized de Bruijn graph assembler, facilitate a comprehensive view on the individual genomes across a wide range of coverage ratios. Testing assemblers on a real‐world metagenome skimming data from the lichen Lasallia pustulata demonstrates the applicability of twin sets for guiding method selection. Furthermore, it reveals that the assembly outcome for the photobiont Trebouxia sp. falls behind the a priori expectation given the simulations. Although the underlying reasons remain still unclear, this highlights that further studies on this organism require special attention during sequence data generation and downstream analysis.     

新疆托木尔峰国家级自然保护区岩面生地衣群落数量分类及其与环境相关性

采用样地法对新疆托木尔峰国家级自然保护区岩面生地衣群落的种类组成进行调查和统计,并以各种类的盖度为指标、应用双向指示种分析( TWINSPAN)和除趋势对应分析( DCA)对岩面生地衣群落进行数量分类;采用S?rensen相似性系数分析各群丛的物种相似性;此外,应用典范对应分析( CCA)探讨了岩面生地衣种类分布与环境因子间的关系。结果表明：该保护区岩面生地衣群落共包含58种地衣,隶属于6目18科35属;优势科有5个,包含的属、种数量分别占该保护区岩面生地衣属、种总数的42.86%和62.07%。依据TWINSPAN和DCA分析结果并结合生境特征,可将该保护区岩面生地衣群落划分为5个群丛：群丛 A,包氏微孢衣+双缘衣群丛( Assoc. Acarospora bohlinii+Diploschistes scruposus);群丛 B,油黄茶渍+亚白平茶渍+柔扁枝衣群丛( Assoc. Candelariella oleifera+Aspicilia subalbicans+Evernia divaricata);群丛C ,斑纹网衣+旱梅衣+淡肤根石耳群丛( Assoc. Lecidea tessellata+Parmelia vegans+Umbilicaria verginis);群丛D,丽石黄衣+白泡鳞衣群丛( Assoc. Xanthoria elegans+Toninia candida);群丛E,皮果衣+硬袋衣群丛( Assoc. Dermatocarpon miniatum+Hypogymnia austerodes)。相似性分析结果表明：群丛A与群丛B、群丛C与群丛D间的物种相似性较高,相似性系数分别为0.615和0.733;群丛B与群丛C间的物种相似性次之,相似性系数为0.363;其他群丛间的物种相似性均较低。 CCA分析结果显示：该保护区岩面生地衣群落的物种分布受到海拔、光照强度、岩面pH值和相对湿度的影响。     

新疆微孢衣属(Acarospora)地衣的中国新记录种(英文)

结合相关的研究资料,对新疆西部部分山区实地采集的地衣标本进行初步整理、分类和鉴定,结果发现了微孢衣属(Acarospora)的3个中国新记录种: Acarospora glaucocarpa,Acarospora peliscypha,Acarospora veronensis。     

Two new guaiane-sesquiterpenes from the cultured lichen mycobiont of Diorygma pruinosum

Lichens and the mycobionts derived from lichen-source are believed to be a valuable source of bioactive compounds. Diorygma pruinosum is a native lichen in Vietnam. A mycobiont of Diorygma pruinosum was separated, then cultivated. Phytochemical data on this lichen and its cultured mycobionts are scarce. The present study described the isolation and structural elucidation of two new guaiane-type sesquiterpenes, namely pruinosone (1) and hydroxypruinosone (2). Their absolute chemical structures were elucidated by extensive 1D and 2D NMR analysis, high-resolution mass spectroscopy, electronic circular dichroism (ECD), and comparisons in the literatures. Compounds 1 and 2 were evaluated for alpha-glucosidase inhibition and antimicrobial activity.