Green Lichens Research Articles

Genome Analysis of Two Lichen Bacteriobionts, <i>Lichenibacterium</i> <i>ramalinae</i> and <i>Lichenibacterium minor</i>: Factors of Virulence and Adaptation

Successful invasion and adaptation of bacteria into lichen symbiosis requires the involvement of a number of physiological mechanisms that regulate interactions between bacteriobionts, mycobionts and algobionts and ensure the optimization of thallus growth and development. The genomes of two lichen bacteriobionts Lichenibacterium ramalinae and L. minor were analysed to identify those factors. No nodulation genes traditional for rhizobia were found. TIGR02302 protein has been suggested to have a similar function. Genes encoding proteins associated with the implementation of planktonic and biofilm phenotypes – flagellins and pilins – have been found. These genes have a high level of similarity with the genes of plant symbiont bacteria. Genetic determinants of virulence factors such as locus B invasion proteins, Integration host factor (IHF), sensory histidine kinases, siderophore receptor and transport proteins and monooxygenase of antibiotic synthesis (Abm) were found in the genomes of the studied bacteria. The listed genes have similarities with those in organisms forming associations of different degrees of association with plants. Based on the data obtained, the assumption of a priority association of bacteria of the Lichenibacteriaceae family with green lichen algae was suggested.

‘Come up to a place like this?’ The Problem with Seeking Sanctuary in the Rural in Mary Lavin's Short Stories

Mary Lavin's stories subtly suggest that the rural idyll that De Valera dreamed of cannot materialise. The past plays heavy on the modernity promised, and through Lavin's ecocritical eye, it creeps in to each of her stories like the ‘powdery green lichen’ that covered the walls in the yard of Ella and Robert's home in ‘A Happy Death’. Her characters are not romantic outsiders but people trying to come to terms with, and move away from, the sentimentality and cliché of Irish identity. The negotiation that the characters undergo, and the influence of this pastoral trope on their lives, is manifested in Lavin's use of ecological signposts. Her stories act as a reminder of this failed rural promise and allow Lavin to make a critical statement on the promise of post-independence Ireland, and the reality of life. The environment becomes a dominating presence on the landscape, both urban and rural and on the characters that inhabit this newly independent state. This article will investigate Lavin's engagement with the rural in her short stories.

Escaping from the City Means More than a Cheap House and a 10-Minute Commute

Escaping from the City Means More than a Cheap House and a 10-Minute Commute

Lichens—a new source or yet unknown host of herbaceous plant viruses?

Lichens are symbiotic associations of fungi with green algae or cyanobacteria. They have arisen independently several times within the Ascomycota and Basidiomycota. This symbiosis became with time one of the most successful life forms on Earth. Outside of the symbiotic algae and fungi, there are endophytic fungi, other algae, and lichen-associated bacteria present within lichen thalli. Till now, no lichen-specific pathogens have been reported among bacteria and viruses. Around 15 dsRNA viruses are known from Eurotiomycetes and another dsRNA and reverse transcribed ssRNA viruses from Dothideomycetes containing some lichenized fungal lineages. Algal viruses have been identified from less than 1 % of known eukaryotic algal species but no virus has been found in Trebouxia or in Trentepohlia (Chlorophyta, Pleurastrophyceae, Pleurastrales), the most common green lichen photobionts. On the other hand, dsDNA viruses infecting related Chlorella algae are well known from freshwater phytoplankton. However, high-molecular weight dsRNA isolated from different lichen thalli indicated to us presence of ss or dsRNA viruses. A PCR-based search for viruses with genus-specific and species-specific primers resulted in amplification of genome segments highly identical with those of plant cytorhabdoviruses and with Apple mosaic virus (ApMV). The nucleotide sequence of the putative lichen cytorhabdovirus showed high identity (98 %) with Ivy latent cytorhabdovirus. The nucleotide sequences of six Apple mosaic virus isolates from lichens showed high similarity with ApMV isolates from apple and pear hosts. The lichen ApMV isolates were mechanically transmitted to an herbaceous host and detected positive in ELISA 14 days thereafter, which support its infectivity on plants. We prepared axenic cultures of photobionts identified as Trebouxia sp. from this ApMV-positive lichen samples. All these cultures were positive for ApMV in RT-PCR test. We suggest that lichens as a whole (or their photobionts, more specifically) could serve as reservoirs for viruses, despite the fact that the way of transmission between different organisms is not clear. We showed that lichens could harbour several viruses simultaneously, as the plant cytorhabdovirus and ApMV were detected in the same host, also.

Desiccation-induced non-radiative dissipation in isolated green lichen algae

Lichens are able to tolerate almost complete desiccation and can quickly resume metabolic activity after rehydration. In the desiccated state, photosynthesis is completely blocked and absorbed excitation energy cannot be used for electron transport, leading to a potential strong vulnerability for high light damage. Although desiccation and high insolation often occur simultaneously and many lichens colonize exposed habitats, these organisms show surprisingly little photodamage. In the desiccated state, variable chlorophyll fluorescence is lost, indicating a suspension of charge separation in photosystem II. At the same time, basal fluorescence (F (0)) is strongly quenched, which has been interpreted as an indication for high photoprotective non-radiative dissipation (NRD) of absorbed excitation energy. In an attempt to provide evidence for a photoprotective function of NRD in the desiccated state, isolated green lichen algae of the species Coccomyxa sp. and Trebouxia asymmetrica were used as experimental system. In contrast to experiments with intact lichens this system provided high reproducibility of the data without major optical artifacts on desiccation. The presence of 5mM trehalose during desiccation had no effect but culture of the algae in seawater enhanced F (0) quenching in T. asymmetrica together with a reduced depression of F (V)/F (M) after high light treatment. While this effect could not be induced using artificial seawater medium lacking trace elements, the addition of ZnCl(2) and NaI in small amounts to the normal growth medium led to qualitatively and quantitatively identical results as with pure seawater. It is concluded that NRD indicated by F (0) quenching is photoprotective. The formation of NRD in lichen algae is apparently partially dependent on the presence of specific micronutrients.

Copper localization, elemental content, and thallus colour in the copper hyperaccumulator lichenLecanora sierraefrom California

AbstractAn unusual dark blue-green lichen,Lecanora sierrae, was discovered over 30 years ago by Czehura near copper mines in the Lights Creek District, Plumas County, Northern California. Using atomic absorption spectroscopy, Czehura found that dark green lichen samples from Warren Canyon contained 4% Cu in ash and suggested that its colour was due to copper accumulation in the cortex. The present study addressed the hypothesis that the green colour in similar material we sampled from Warren Canyon in 2008, is caused by copper localization in the thallus. Optical microscopy and electron microprobe analysis of specimens ofL. sierraeconfirmed that copper localization took place in the cortex. Elemental analyses ofL. sierraeand three other species from the same localities showed high enrichments of copper and selenium, suggesting that copper selenates or selenites might occur in these lichens and be responsible for the unusual colour.

Damage evaluation and conservation treatment of the tenth century Korean rock-carved Buddha statues

This study focuses on the lithological characterization, quantitative deterioration assessment and conservation treatment of the tenth century rock-carved Buddha statues in Korea. The Buddha statues were carved on light gray macrocrystalline biotite granite, and features microcline phenocrysts and pegmatite patches. The rock-forming minerals are quartz, plagioclase, microcline and biotite showing micrographic and porphyritic textures. Feldspars and biotite in the host rock have been partly altered into sericite and chlorite by weathering. The surface of the Buddha statues is remarkably irregular due to granular disintegration and the differential weathering of the quartz and microcline. In addition, horizontal and vertical cracks in the host rock have promoted mechanical weathering. Biological colonization of the statues was serious, and featured dark gray and yellowish green lichen, dark green bryophyte and some plants. The Buddha statues were evaluated as the highly weathered rock by ultrasonic survey. The lower parts under the influence of water and areas with severely broken surfaces showed a much more advanced weathering grade. Therefore, scientific conservation treatment was carried out for the long-term maintenance and conservation of the Buddha statues. After pretests, dry, wet and chemical cleanings were applied to the statues. Next, joining of cracked parts and surface consolidating were executed. Finally, the site environment was improved by installation of drain and trimming trees around the statues to ensure more stable long-term conservation.

BOTRYOLEPRARIA, A NEW MONOTYPIC GENUS SEGREGATED FROMLEPRARIA

The monotypic genusBotryoleprariaCanalset al. is described. The type species,B. lesdainii(Hue) Canalset al. is a sterile, cottony, pale green lichen, made of hyphae supporting subterminal bunches of chlorophycean algae.

コロラド・ロッキー山脈，フロントレンジ，ナバホ氷河周辺の“プロテーラスランパート”の再検討，および後期更新世〜完新世のナバホ氷河の復元

The air-photo interpretations and the casual field observations in the Navajo Glacier area, the uppermost reaches of the South St. Vrain Creek, Colorado Front Range, led to the speculation that the Triple Lakes “protalus ramparts” which were identified by Benedict (1968) can be classified into the following three different landforms:(1) a ridge located at the highest altitude (U1) regarded as a protalus rampart, while another in the center can be subdivided and classified into (2) a protalus rampart (U2: upper unit) and (3) a lateral moraine (L: lower unit). Several lines of evidence support the above classification. Firstly, the lower unit (L) has a flat surface with vegetation cover. Secondly, the lower unit (L) continues to an arcshaped ridge downvalley. Thirdly, the upper unit (U2) has the same sinuosity as that of U1 and the talus slope but the lower unit (L) does not. Finally, the lower unit (L) has fine matrix whereas the upper unit (U2) does not.Multiple relative dating methods, such as lichenometry (lichen diameter, percent lichen cover, and ratio of green lichens/{brown and black lichens}), weathering rind thickness, SGW I (surface granite weathering index of Benedict, 1985), and pit depth, provided the estimated age of Triple Lakes (3, 000-5, 200 y. B. P.) for both the moraine and the protalus rampart classified above. However, soil profiles and soil color indices (Buntley-Westin and Hurst color indices) indicate that the moraine is older than the protalus rampart. It is probable that the lichenometric and weathering feature data collected from the lateral moraine surface have been influenced by rockfall activity which modified the moraine surface during the Triple Lakes period. The protalus rampart (U2) is estimated to have been formed in the Triple Lakes Stade, as Benedict (1968) states. However, the moraine seems to be of the Satanta Peak Stade (10, 000-12, 000 y. B. P.), which is recognized elsewhere in the Colorado Front Range (Birkeland et al., 1987).Using this result together with the method for estimating glacier ice thickness of Porter et al.(1983), this study has also attempted to reconstruct the Navajo Glacier in the Late Stade of Pinedale and the Satanta Peak and Triple Lakes stades. The glacier is believed to have terminated at an altitude of 3, 250-3, 300m in this valley in the Late Stade of Pinedale (-14, 000 y. B. P.)(Madole, 1969), at which time the area and thickness of the glacier are estimated to have been 5.6km2 and 250m, respectively. In the Satanta Peak Stade (12, 000-10, 000 y. B. P.), the glacier retreated to 3, 480m, and its area and thickness decreased to 1.0km 2 and 100m, respectively. The Triple Lakes glacier terminated at an altitude of 3, 680m in the cirque, with an area of 0.2km 2 and a thickness of 25-30m.

Water status related photosynthesis and carbon isotope discrimination in species of the lichen genusPseudocyphellaria with green or blue-green photobionts and in photosymbiodemes.

Green lichens have been shown to attain positive net photosynthesis in the presence of water vapour while blue-green lichens require liquid water (Lange et al. 1986). This behaviour is confirmed not only for species with differing photobionts in the genusPseudocyphellaria but for green and blue-green photobionts in a single joined thallus (photosymbiodeme), with a single mycobiont, and also when adjacent as co-primary photobionts. The different response is therefore a property of the photobiont. The results are consistent with published photosynthesis/water content response curves. The minimum thallus water content for positive net photosynthesis appears to be much lower in green lichens (15% to 30%, related to dry weight) compared to blue-greens (85% to 100%). Since both types of lichen rehydrate to about 50% water content by water vapour uptake only green lichens will show positive net photosynthesis. It is proposed that the presence of sugar alcohols in green algae allow them to retain a liquid pool (concentrated solution) in their chloroplasts at low water potentials and even to reform it by water vapour uptake after being dried. The previously shown difference in δ13C values between blue-green and green lichens is also retained in a photosymbiodeme and must be photobiont determined. The wide range of δ13C values in lichens can be explained by a C3 carboxylation system and the various effects of different limiting processes for photosynthetic CO2 fixation. If carboxylation is rate limiting, there will be a strong discrimination of13CO2, at high internal CO2 partial pressure. The resulting very low δ13C values (-31 to-35‰) have been found only in green lichens which are able to photosynthesize at low thallus water content by equilibraiton with water vapour. When the liquid phase diffusion of CO2 becomes more and more rate limiting and the internal CO2 pressure decreases, the13C content of the photosynthates increases and less negative δ13C values results, as are found for blue-green lichens.