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Antarctic lichens have been used as indicators of climate change for decades, but only a few species have been studied. We assessed the photosynthetic performance of the fruticose lichen Cladonia borealis under natural and laboratory conditions using the PAM fluorescence system. Compared to that of sun-adapted Usnea sp., the photosynthetic performance of C. borealis exhibits shade-adapted lichen features, and its chlorophyll fluorescence does not occur during dry days without rain. To understand its desiccation-rehydration responses, we measured changes in the PSII photochemistry in C. borealis under the average light intensity of dawn light and daylight and the desiccating conditions of its natural microclimate. Interestingly, samples under daylight and rapid-desiccation conditions showed a delayed reduction in Fv&rsquo, /Fm&rsquo, and rETRmax, and an increase in Y(II) and Y(NPQ) levels. These results suggest that the photoprotective mechanism of C. borealis depends on sunlight and becomes more efficient with improved desiccation tolerance. Amplicon sequencing revealed that the major photobiont of C. borealis was Asterochloris irregularis, which has not been reported in Antarctica before. Collectively, these results from both field and laboratory could provide a better understanding of specific ecophysiological responses of shade-adapted lichens in the Antarctic region.

Resistant bacterial infections are a major public health problem worldwide, which entails the need to search for new therapeutic agents. In this context, lichens stand out, provided that they are producers of structurally diverse compounds that have attractive biological properties, including antimicrobial activity. Thus, extracts of 12 lichen species were prepared and their potential to inhibit the growth of 5 bacterial strains was evaluated in this work. The chemical compositions of these extracts were examined using TLC and microcrystallization, being the identity of the active compounds in each extract attributed based on the bioautography technique. The most active extracts (and their identified active compounds) were from Cladonia borealis (usnic, barbatic and 4-O-demethylbarbatic acids), Cladina confusa (usnic and perlatolic acids), Stereocaulom ramulosum (atranorin, perlatolic and anziaic acids) and Canoparmelia cryptochlorophaea (cryptochlorophaeic and caperatic acids), with MICs ranging from 7.8 to 31.25 μg/mL, including for resistant clinical strains. MIC values ​​were also obtained for substances isolated from lichens for comparison purposes. A group of four extracts containing usnic acid was analyzed by 1H NMR in order to correlate relative proportion of major metabolites and extracts activity. The less active extracts in this group, in fact, presented low proportion of usnic acid.

espanolComo consecuencia de las recolecciones efectuadas en varios periodos durante los anos 2009-2017, se amplia a 27 especies el numero de Cladoniaceae, ademas se aportan 15 nuevas especies de Cladonia para Albania. Se amplia la distribucion de muchos de los taxones citados con anterioridad y se discute la variabilidad quimica en la mayoria de las especies encontradas. Cladonia borealis, C. caespiticia, C. cervicornis, C. coccifera, C. conista, C. cryptochlorophaea, C. cyathomorpha, C. humilis, C. merochlorophaea, C. parasitica, C. peziziformis, C. polycarpoides, C. ramulosa, C. rei y C. subulata son nuevas para Albania. EnglishAs a result of collections made during the years 2009-2017, the number of Cladoniaceae species is enlarged to 27 species, providing fifteen new records to Albanian Cladonia. The distribution of many of the previously mentioned taxa is extended and the chemical variability for many of the species is discussed. Cladonia borealis, C. caespiticia, C. cervicornis, C. coccifera, C. conista, C. cryptochlorophaea, C. cyathomorpha, C. humilis, C. merochlorophaea,C. parasitica, C. peziziformis, C. polycarpoides, C. ramulosa, C. rei and C. subulata are new for Albania.