Do photobionts influence the ecology of lichens? A case study of environmental preferences in symbiotic green alga Asterochloris (Trebouxiophyceae)

The distribution patterns of symbiotic algae are thought to be conferred mainly by their hosts, however, they may originate in algal environmental requirements as well. In lichens, predominantly terrestrial associations of fungi with algae or cyanobacteria, the ecological preferences of photobionts have not been directly studied so far. Here, we examine the putative environmental requirements in lichenized alga Asterochloris, and search for the existence of ecological guilds in Asterochloris-associating lichens. Therefore, the presence of phylogenetic signal in several environmental traits was tested. Phylogenetic analysis based on the concatenated set of internal transcribed spacer rDNA and actin type I intron sequences from photobionts associated with lichens of the genera Lepraria and Stereocaulon (Stereocaulaceae, Ascomycota) revealed 13 moderately to well-resolved clades. Photobionts from particular algal clades were found to be associated with taxonomically different, but ecologically similar lichens. The rain and sun exposure were the most significant environmental factor, clearly distinguishing the Asterochloris lineages. The photobionts from ombrophobic and ombrophilic lichens were clustered in completely distinct clades. Moreover, two photobiont taxa were obviously differentiated based on their substrate and climatic preferences. Our study, thus reveals that the photobiont, generally the subsidiary member of the symbiotic lichen association, could exhibit clear preferences for environmental factors. These algal preferences may limit the ecological niches available to lichens and lead to the existence of specific lichen guilds.     

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.     

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。     

异极衣纲一新种和四中国新记录分类单元

异极衣纲Lichinomycetes仅含异极衣目Lichinales,异极衣目内含3科：球蜂窝衣科Gloeoheppiaceae、异极衣科Lichinaceae和盾衣科Peltulaceae。本文基于表型特征对中国异极衣纲地衣分类研究发现新种1个：近叉指盾链衣Digitothyrea subdivergens,中国新记录属1个：指盾链衣属Digitothyrea,中国新记录种3个：白棋盘蜂窝衣Heppia solorinoides、朝氏盾链衣Thyrea asahinae和吉拉氏盾链衣Thyrea girardii,与形态相似种进行了比较和讨论。本研究不仅为中国地衣志的编研积累资料,同时为开展利用地衣结皮实施“沙漠生物地毯工程”储备资源信息。     

康复新液与他克莫司联合沙利度胺治疗口腔扁平苔藓的疗效及安全性分析

目的:探讨康复新液与他克莫司联合沙利度胺治疗口腔扁平苔藓(oral lichen planus,OLP)的临床疗效及安全性。方法:选择2017年12月-2020年1月就诊于我院的80例OLP患者,采用随机数字表法将其分为联合组和对照组,每组40例。两组均进行常规治疗,对照组使用0.1%的他克莫司软膏与康复新液治疗,联合组在对照组的基础上加用沙利度胺片,比较两组的临床疗效、治疗前后糜烂面大小、疼痛程度的变化以及不良反应的发生情况。结果:治疗后,联合组总有效率为90.00%,显著高于对照组(72.5%,P0.05);与治疗前相比,两组口腔糜烂面积和疼痛程度均显著降低(P 0.05),且联合组口腔糜烂面积和疼痛程度显著低于对照组(P 0.05);治疗期间,对照组出现1例不良反应,具体表现为轻微的黏膜烧灼痛,停药后两天后症状消失,不良反应发生率为2.5%,联合组出现2例不良反应,其中1例病变部位出现黏膜萎缩,1例出现色素沉着,不良反应发生率为5.0%,两组不良反应的发生率比较无显著差异(P0.05)。结论:康复新液与他克莫司联合沙利度胺治疗口腔扁平苔藓的临床疗效明显优于康复新液与他克莫司治疗,其能明显降低粘膜糜烂面积和疼痛程度,且安全性高。     

Structure and Chemical Analysis of Major Specialized Metabolites Produced by the Lichen Evernia prunastri

We performed comparative profiling of four specialized metabolites in the lichen Evernia prunastri, collected at three different geographic locations, California and Maine, USA, and Yoshkar Ola, Mari El, Russia. Among the compounds produced at high concentrations that were identified in all three specimens, evernic acid, usnic acid, lecanoric acid and chloroatranorin, evernic acid was the most abundant. Two depsidones, salazinic acid and physodic acid, were detected in the Yoshkar‐Ola collection only. The crystalline structure of evernic acid (2‐hydroxy‐4‐[(2‐hydroxy‐4‐methoxy‐6‐methylbenzoyl)oxy]‐6‐methylbenzoate) (hmb) revealed two crystallographically and conformationally distinct hmb anions, along with two monovalent sodium atoms. One hmb moiety contained an exotetradentate binding mode to sodium, whereas the other exhibited an exohexadentate binding mode to sodium. Embedded edge‐sharing {Na₂O₈}_n sodium‐oxygen chains connected the hmb anions into the full three‐dimensional crystal structure of the title compound. The crystal used for single‐crystal X‐ray diffraction exhibited non‐merohedral twinning. The data suggest the importance of the acetyl‐polymalonyl pathway products to processes of maintaining integrity of the lichen holobiont community.     

The pervasive and multifaceted influence of biocrusts on water in the world's drylands

The capture and use of water are critically important in drylands, which collectively constitute Earth's largest biome. Drylands will likely experience lower and more unreliable rainfall as climatic conditions change over the next century. Dryland soils support a rich community of microphytic organisms (biocrusts), which are critically important because they regulate the delivery and retention of water. Yet despite their hydrological significance, a global synthesis of their effects on hydrology is lacking. We synthesized 2,997 observations from 109 publications to explore how biocrusts affected five hydrological processes (times to ponding and runoff, early [sorptivity] and final [infiltration] stages of water flow into soil, and the rate or volume of runoff) and two hydrological outcomes (moisture storage, sediment production). We found that increasing biocrust cover reduced the time for water to pond on the surface (?40%) and commence runoff (?33%), and reduced infiltration (?34%) and sediment production (?68%). Greater biocrust cover had no significant effect on sorptivity or runoff rate/amount, but increased moisture storage (+14%). Infiltration declined most (?56%) at fine scales, and moisture storage was greatest (+36%) at large scales. Effects of biocrust type (cyanobacteria, lichen, moss, mixed), soil texture (sand, loam, clay), and climatic zone (arid, semiarid, dry subhumid) were nuanced. Our synthesis provides novel insights into the magnitude, processes, and contexts of biocrust effects in drylands. This information is critical to improve our capacity to manage dwindling dryland water supplies as Earth becomes hotter and drier.     

Woodpeckers can act as dispersal vectors for fungi,plants, and microorganisms

Bird‐mediated dispersal is presumed to be important in the dissemination of many different types of organisms, but concrete evidence remains scarce. This is especially true for biota producing microscopic propagules. Tree‐dwelling birds, such as woodpeckers, would seem to represent ideal dispersal vectors for organisms growing on standing tree trunks such as epiphytic lichens and fungi. Here, we utilize bird natural history collections as a novel source of data for studying dispersal ecology of plants, fungi, and microorganisms. We screened freshly preserved specimens of three Finnish woodpecker species for microscopic propagules. Samples were taken from bird feet, and chest and tail feathers. Propagules were extracted using a sonication–centrifugation protocol, and the material obtained was studied using light microscopy. Diverse biological material was recovered from all specimens of all bird species, from all positions sampled. Most abundant categories of discovered biological material included bryophyte fragments, fungal spores, and vegetative propagules of lichens. Also, freshwater diatoms, bryophyte spores, algal cells, testate amebae, rotifers, nematodes, pollen, and insect scales were identified. The method developed here is applicable to living specimens as well, making it a versatile tool for further research. Our findings highlight the potential of bird‐mediated dispersal for diverse organisms and showcase the use of natural history collections in ecological research.     

Detection and identification of non-Candida albicans species in human oral lichen planus

Candida species were detected and identified in samples from the buccal mucosa, dorsal surface of the tongue and supragingival plaque of subjects with oral lichen planus (OLP). The Candida in the samples were cultured on selection agars, and identified by sequence analyses of 18S, 5.8S and 25/28S rRNA. The isolation frequency of Candida was higher in subjects with OLP than in those with healthy oral mucosa. Non-C. albicans were only isolated from people with OLP. These results support the notion that subjects with OLP are more likely to have oral colonization with Candida, and that non-C. albicans are specifically present in subjects with this condition.