Lichen Peltigera Canina Research Articles

Impacts of Mineral Dust on Trace Element Concentrations (As, Cd, Cu, Ni and Pb) in Lichens and Soils at Lhù’ààn Mân’ (Yukon Territory, Canada)

AbstractDust is a mineral aerosol of the atmosphere that often contains trace elements such as As, Cd, and Pb. Lhù’ààn Mân’ (Kluane Lake), located in southwestern Yukon, is a region of frequent dust activity. In 2016, the lake level fell due to a dramatic decrease in inflow from glacier meltwater, and the delta of the lake became an important source of dust to surrounding ecosystems. To determine the impacts of dust deposition on vegetation and soil trace element concentrations and characteristics, we sampled the lichen Peltigera canina and soil layers at 57 sites along a deposition gradient located 1.4–33.6 km downwind from the principal dust source. Arsenic, Cd, Cu, Ni and Pb in lichens were negatively correlated with the distance away from the dust source, with the highest correlations in Ni and Pb (r2 = 0.50 and 0.48, respectively). Lichen and tree abundances were negatively impacted by dust deposition, suggesting that dust can affect ecosystem vegetation composition. Starting 8 km away from the dust source, the concentrations of As, Ni, and Pb decreased by more than 50% per km, while Cd and Cu concentrations decreased by more than 40% per km. Overall, within the sampled ecosystems, soil pH is 1.4 times higher in the first 8 km from the dust source while carbon content and nutrients are lower, which implies changes in nutrient availability and cycling in dust‐affected ecosystems.

Effects of the lichen Peltigera canina on Cucurbita pepo spp. pepo grown in soil contaminated by DDTs.

Lichens consisting of a symbiotic association of green algae or cyanobacteria and fungi are found in a variety of environmental conditions worldwide. Terricolous lichens, located in soils, affect the living and lifeless environment of the soil due to their effective secondary metabolite and enzymatic content. Terricolous lichens can increase the biological, chemical, and physical usefulness of soil. However, their effects in ensuring the bioavailability of contaminated soil are not known, especially on soil pollution caused by DDTs (p,p'-DDE, p,p'-DDD, p,p'-DDT). This research focuses on the effect of terricolous lichens on zucchini (Cucurbita pepo spp. pepo) grown in soil contaminated by DDTs, utilizing their secondary metabolite and enzymatic contents. Firstly, Peltigera canina, a terricolous lichen species, was added to soil contaminated by DDTs as powdered and intact thallus. After lichen addition to soil, zucchini was planted in. The oxidative stress and antioxidative enzyme activities of zucchini were measured. According to the results, P. canina treatments have a positive effect on the growth and development of zucchini, although oxidative stress was observed. Also, it was determined that powdered application had more effective results than intact thallus application.

An actomyosin-like cytoskeleton in the cyanobiont (Nosctoc sp.) of Peltigera canina

Lichenized Nostoc cells isolated from the lichen Peltigera canina develop chemotaxis towards a lectin purified from the lichen thallus. Similar movements in unicellular eukaryotes require actin and myosin to generate contraction and relaxation along the chemotactic axis. We provide evidences for prokaryotic actin-like and myosin-like proteins in the cyanobiont Nostoc sp using cross-reacting antibodies against α- and β-actin and non-muscle myosin II light and heavy chains, and two-dimensional gel electrophoresis to determine the isoelectric point (IP) of the actin-like protein. Actin antibodies bound to a single reactive Nostoc polypeptide of an approximate molecular mass of 50kD with IP values between 4 and 7pH, similar to eukaryotic actin. The myosin light chain antibody reacted with a Nostoc protein with an apparent molecular weight of 20kDa and another of 48kDa. Immunoprecipitation of cell free extracts using anti-heavy chain myosin separately yielded only one signal corresponding to a protein of a molecular weight around 200kDa. A bioinformatics analysis indicated that (cyano)bacterial actins are rare but do exist. Our results are consistent with the possible existence of protein homologues of actins and myosins in cyanobionts of P. canina, suggesting the existence of an actin-like apparatus that supports chemotactic swimming.

A cyanobacterial β-actin-like protein, responsible for lichenized Nostoc sp. motility towards a fungal lectin

Lichenized Nostoc cells isolated from the lichen Peltigera canina develop chemotactic movement towards a lectin purified from the lichen thallus. Inhibitors of cytoskeleton dynamics, such as phalloidin, latrunculin A and blebbistatin, impede cell displacement. The inhibition of chemotaxis produced by the combined action of phalloidin and blebbistatin is largely reversed by GTP and its analogs, GTP(γ)S and GDP(β)S, as well as by cyclic AMP. Movement implies a rearrangement of the cytoskeleton causing cell polarity, which is, in turn, inhibited by phalloidin and latrunculin A, as revealed by confocal microscopy. F-actin fibers composing Nostoc cytoskeleton have been visualized by immunocytochemical techniques associated with transmission electron microscopy.

Isolation and characterization of a cyanobacterium-binding protein and its cell wall receptor in the lichen Peltigera canina

Peltigera canina, a cyanolichen containing Nostoc as cyanobiont, produces and secretes arginase to a medium containing arginine. Secreted arginase acts as a lectin by binding to the surface of Nostoc cells through a specific receptor which develops urease activity. The enzyme urease has been located in the cell wall of recently isolated cyanobionts. Cytochemical detection of urease is achieved by producing a black, electron-dense precipitate of cobalt sulfide proceeding from CO2 evolved from urea hydrolysis in the presence of cobalt chloride. This urease has been pre-purified by affinity chromatography on a bead of active agarose to which arginase was attached. Urease was eluted from the beads by 50 mM α-D-galactose. The experimentally probed fact that a fungal lectin developing subsidiary arginase activity acts as a recognition factor of compatible algal cells in chlorolichens can now been expanded to cyanolichens.

Structural characterisation of a highly branched galactomannan from the lichen Peltigera canina by methylation analysis and NMR-spectroscopy

An alkali-extractable water-soluble polysaccharide, Pc-4, was isolated from the lichen Peltigera canina using ethanol fractionation and size exclusion chromatography. The average molecular weight of Pc-4 was estimated to be 53 kDa. Structural characterisation of Pc-4 was performed by methanolysis, methylation analysis and NMR-spectroscopy (1D proton, COSY, NOESY, TOCSY and HSQC). According to data obtained, Pc-4 is a highly branched galactomannan, with (1→6)-linked α-mannopyranosyl units in the main chain, which are mainly disubstituted at O2 and O4 by single unsubstituted units of α-Man p and β-Gal p, respectively. Pc-4 resembles the lichen galactomannans described previously; however, Pc-4 has higher degree of branching.

Effects of lichen heteroglycans on proliferation and IL-10 secretion by rat spleen cells and IL-10 and TNF-α secretion by rat peritoneal macrophages in vitro

Four polysaccharides Pc-1, Pc-2, Pc-3 and Pc-4 were isolated from water and alkali extracts of the lichen Peltigera canina using ethanol fractionation, gel filtration and preparative HP-GPC. The monosaccharide composition was determined by methanolysis and GC and showed mannose and galactose as the predominating structural units. The mean M(r) was determined by HP-GPC. The heteroglycans were tested for in vitro immunomodulating activities and showed mitogenic activity in rat spleen cell proliferation assay and stimulated IL-10 secretion. In rat peritoneal macrophages, the heteroglycans stimulated TNF-alpha secretion, but not IL-10 secretion. These results indicate that the polysaccharides influence cells of the immune system both from the innate and the adaptive systems.

Reconstitution of the symbiosis of Gunnera manicata Linden: cyanobacterial specificity

SUMMARYThe ability of various cyanobacteria to establish a symbiosis with Gunnera manicata Linden was examined under sterile conditions. Cyanobacterial strains were classified as infective if they could be found in a well‐defined infected area within the Gunnera gland tissue 40 d after inoculation. Nine out of 17 tested Nostoc strains were able to infect G. manicata. The infecting strains were all symbiotic isolates. These included six out of ten isolates from Gunnera spp., the isolate from the cycad Macrozamia sp., that from the hornwort Anthocerns sp., and that from the lichen Peltigera canina. None of the seven strains belonging to genera other than Nostne was capable of infection, even though the majority of them were also able to form motile hormogonia. Negative staining revealed fimbria‐like structures in both infective and non‐infective strains. In fact, two of the non‐infecting strains had the most abundant fimbria‐like filaments. No conspicuous structural or ultrastructural differences between infecting and non‐infecting strains were detected using light‐ and transmission electron microscopy. We conclude that selection between conceivable microsymbionts is exerted at the recognition and/or entrance stage.

Mise en evidence, controle de l'action de la pollution sur les lichens ( Peltigera canina) par utilisation du film infrarouge couleurs

This study describes experiments on the lichen Peltigera canina from unpolluted and polluted urban locations. This study involved analysis by infrared color photography (IRC), digitalization, and data processing. Spectral responses of the lichen from unpolluted and polluted areas are compared in order to consider pollutant action: changes of spectra responses in the visible and infrared bands and decreases of vegetation index (IR/R).

Influence d'une atmosphere urbaine sur les differentes fonctions d'une espece lichenique. Etude “in situ” et en chambrettes experimentales

Samples of the lichen Peltigera canina were placed in a reference zone and in an urban atmosphere (Toulouse, France) for different lengths of time. A systematic study was carried out in order to evaluate the metabolic consequences of stress caused by the action of pollution. Thalli of the same origin, placed in experimental chambers, were submitted to the action of pollutants (SO 2, NO 2) in order to make a comparative study. The principal metabolic functions were affected and changes in physiological activity were often evident in spite of the fact that no real external lesions could be observed. In spite of specific differences, the results obtained for photosynthesis, respiration and nitrogen fixation suggest similar sequences for the processes. The changes in metabolism are revealed by an increase in the pool of free amino acids and a decrease of protein synthesis in the case of a polluted atmosphere. Some marked variations could possibly be used as indicators of environmental modification.

The Nostoc‐Nephroma symbiosis: localization, distribution pattern and levels of key proteins involved in nitrogen and carbon metabolism of the cyanobiont

The qualitative distribution and quantitative estimates of nitrogenase (EC 1.7.99.2), glutamine synthetase (EC 6.3.1.2), phycoerythrin and ribulose 1,5‐bisphosphate carboxylase/oxygenase (EC 4.1.1.39) were studied in the cyanobacterium Nostoc residing in internal cephalodia of the tripartite lichen Nephroma arcticum L. Polyclonal antisera, raised in rabbit against the proteins, and goat anti‐rabbit IgG conjugated to 10 nm gold were used as probes to detect the antigens by transmission electron microscopy. Western blot analyses demonstrated the monospecificity of the antisera. Nitrogenase was localized in heterocysts, with vegetative cells showing a label intensity comparable to the background. Distribution of the antigen within the heterocysts was uniform. Glutamine synthetase labelling was very low, but appeared to be distributed in both cell types. An intense phycoerythrin labelling was associated with the thylakoid region of the vegetative cells, whereas a much lower labelling was observed in the heterocyst. No significant differences were found between cyanobionts in younger and older cephalodia except for the nitrogenase labelling, which was higher in heterocysts of the cyanobiont in younger cephalodia. Most of the ribulose 1,5‐bisphosphate carboxylase/oxygenase (Rubisco) label was present in vegetative cells. The Rubisco label was pronounced in the carboxysomes, whereas the label in the cytoplasm, on a unit area basis, was much lower. Heterocysts showed a label intensity similar to that of the vegetative cell cytoplasm. In Nostoc of the bipartite lichen Peltigera canina L., the Rubisco protein showed a comparable distribution pattern, but the average number of carboxysomes per vegetative cell was about 4 times higher.

PURIFIED PHYTOLECTIN FROM THE LICHEN PELTIGERACANINA VAR CANINA WHICH BINDS TO THE PHYCOBIONT CELL WALLS AND ITS USE AS CYTOCHEMICAL MARKER IN SITU

SummaryA purified phytolectin was isolated from the nitrogen‐fixing lichen Peltigera canina var canina. This lectin was thermostable, truly non‐specific and may have a molecular weight in its native form of the order of 80000 to 90000. It binds to the appropriate phycobiont cell walls and may be involved in some way in the recognition of, or interactions between, compatible lichen symbionts; it may be used in situ as a cytochemical marker of the free receptor sites in the lichen thalli. We advance a hypothesis that within the lichen the morphological and physiological state of the phycobiont is different in the various parts of the thallus; the capacity of the phycobiont to bind to lectins varies with fluctuations in the symbiotic relationship between partners.

Interactions between cyanobacterium and fungus during 15N2-incorporation and metabolism in the lichen Peltigera canina

On following N2-incorporation and subsequent metabolism in the lichen Peltigera canina using 15N as tracer, it was found, over a 30 min period, that greatest initial labelling was into NH 4 + followed by glutamate and the amide-N of glutamine. Labelling of the amino-N of glutamine, aspartate and alanine increased slowly. Pulse-chase experiments using 15N confirmed this pattern. On inhibiting the GS-GOGAT pathway using l-methionine-dl-sulphoximine and azaserine, 15N enrichment of glutamate, alanine and aspartate continued although labelling of glutamine was undetectable. From this and enzymic data, NH 4 + assimilation in the P. canina thallus appears to proceed via GS-GOGAT in the cyanobacterium and via GDH in the fungus; aminotransferases were present in both partners. The cyanobacterium assimilated 44% of the 15N2 fixed; the remainder was liberated almost exclusively as NH 4 + and then assimilated by fungal GDH.

Nostoc of Peltigera canina when lichenized and isolated

The cyanobiont Nostoc sp. from the lichen Peltigera canina was compared at the ultrastructural level when in its free-living and lichenized stages, as were certain of its physiological characters. The main results may be summarized as follows. The isolated cyanobiont shows typical Nostoc characters and resembles N. sphaericum and N. punctiforme. When lichenized, the vegetative cells are enlarged from 2.5 to 4.5 μm in average diameter. The thylakoids increase in number. They are arranged in a reticular manner and spread throughout the cytoplasm. Phycobilisomes are found and the phycobiliproteins show chromatic adaptation. In the symbiosis the heterocyst frequency of Nostoc is considerably lower at the thallus margins than in more mature thalus parts and the nitrogenase activity correlates with the heterocyst frequency. For the first time, Nostoc akinetes are reported in a lichen.

NITROGEN FIXATION RATE AND CHLOROPHYLL CONTENT OF THE LICHEN PELTIGERA CANINA EXPOSED TO SULFUR DIOXIDE

In general, the rate of nitrogen fixation decreased when the lichen Peltigera canina (L.) Willd. was exposed to sulfur dioxide gas at levels from 0.1 to 500 ppm; at 30 ppm, however, nitrogen fixation was stimulated. Chlorophyll content decreased as level of sulfur dioxide increased.

The occurrence of fimbriae on a N 2 2 -fixing cyanobacterium which occurs in lichen symbiosis

The Nostoc cyanobiont of the lichen Peltigera canina when grown on N2 possesses, in the motile stage, discrete unbranched non-flagellar appendages (fimbriae or pili). These arise from the host cell surface in a peritrichous manner, have an axial hole, are 7.0 ±0.3 nm in diameter and are up to 3 μm long. They do not haemagglutinate guinea pig red blood corpuscles and differ from the major fimbrial types reported for Gram-negative heterotrophic bacteria and from sex pili. They may be involved in motility and specificity in symbiotic cyanobacteria.

PHYSIOLOGICAL‐ENVIRONMENTAL INTERACTIONS IN LICHENS. VII. THE ENVIRONMENTAL CONTROL OF GLUCOSE MOVEMENT FROM ALGA TO FUNGUS IN PELTIGERA CANINA V. PRAETEXTATA HUE

SummaryThe movement of labelled glucose from the phycobiont of the lichen Peltigera canina v. praetextata Hue., to the mycobiont, has been examined under contrasting environmental conditions of temperature and moisture. The ratio of labelled mannitol : labelled photosynthetic products is used as a relative measure of the rate of transport of glucose and its incorporation into mannitol.The relative amount of label appearing in mannitol remains fairly constant over a wide range of experimental temperatures, but there is a marked interaction with the level of thallus hydration. At 100% thallus water content by weight, when high rates of photosynthesis are still maintained, only a small proportion of the total label appears in mannitol. It is suggested that this retention of photosynthate at low levels of thallus saturation is essential to supply the basic metabolic requirements of the phycobiont. Conversely the requirements of the fungal partner are satisfied at higher levels of thallus saturation. Thus alternate wetting and drying cycles are essential to maintain the metabolic requirements of each of the bionts and hence the physical integrity of the lichen itself. The results are briefly discussed in terms of the facilitated diffusion of glucose proposed by Smith (1974).

Die kohlenwasserstoffe der blaualgen-flechte Peltigera canina (L.) Willd.

Summary The hydrocarbon-fraction of Peltigera canina yielded a homologous series of n-alkanes (27%) ranging in chain length from C 13 to C 37 , n-heptadecane (17.1%) being the main representative. Predominant in this fraction was a series of n-alkenes (73%) with chain lengths from C 15 to C 35 . The major components were isomeric heptadecenes (63.9%). With the aid of infrared spectrophotometry and combined gas chromatography mass spectrometry of the corresponding di-O-trimethylsilylglycol derivatives the major alkene components could be identified as Δ 5 cis heptadecene (29.4%) Δ 3 cis heptadecene (34.5%), Δ 6 cis octadecene (6.6%) and Δ 7 cis nonadecene (0.1%). Traces of Δ 4 cis hexadecene, Δ 7 octadecene, Δ 7 and Δ 9 heptadecene could also be found. The influence of algae or fungi on the hydrocarbon pattern from the lichen Peltigera canina is discussed.

The temperature dependence of thallus nitrogenase activity in Peltigera canina

Comparative rates of nitrogen fixation in the lichen Peltigera canina from subarctic and temperate habitats have been examined using the acetylene reduction method. Maximum acetylene reduction at thallus saturation and with 20000 lx illumination takes place at 16 °C in subarctic material and at 21 °C in temperate material. This adaptation of nitrogenase activity to temperature in P. canina is discussed in relation to low levels of soil nitrogen in arctic systems.

NITROGEN METABOLISM IN LICHENS IV. THE NITROGENASE ACTIVITY OF THE NOSTOC PHYCOBIONT IN PELTIGERA CANINA

SummaryThe content of the blue‐green alga phycobiont, Nostoc sp. in the lichen Peltigera canina has been estimated using various techniques and represents on average 2.7% of the total thallus nitrogen. Expressed in terms of cell numbers, this represents approximately 3 × 106 cells cm2, mature thallus. The nitrogenase activity, expressed as nil ethylene evolved/minute/mg Sostoc protein, varies considerably with the thallus sample, but a mean value of 10, considerably greater than that in free‐living Nostoc, has been found. The nitrogenase activity of the algal cells is particularly sensitive to disturbance of the thallus structure and the implications of these findings are discussed.