While photosynthetic processes have become increasingly understood in cyanobacterial model strains, differences in the spatial distribution of thylakoid membranes among various lineages have been largely unexplored. Cyanobacterial cells exhibit an intriguing diversity in thylakoid arrangements, ranging from simple parietal to radial, coiled, parallel, and special types. Although metabolic background of their variability remains unknown, it has been suggested that thylakoid patterns are stable in certain phylogenetic clades. For decades, thylakoid arrangements have been used in cyanobacterial classification as one of the crucial characters for definition of taxa. The last comprehensive study addressing their evolutionary history in cyanobacteria was published 15 years ago. Since then both DNA sequence and electron microscopy data have grown rapidly. In the current study, we map ultrastructural data of >200 strains onto the SSU rRNA gene tree, and the resulting phylogeny is compared to a phylogenomic tree. Changes in thylakoid architecture in general follow the phylogeny of housekeeping loci. Parietal arrangement is resolved as the original thylakoid organization, evolving into complex arrangement in the most derived group of heterocytous cyanobacteria. Cyanobacteria occupying intermediate phylogenetic positions (greater filamentous, coccoid, and baeocytous types) exhibit fascicular, radial, and parallel arrangements, partly tracing the reconstructed course of phylogenetic branching. Contrary to previous studies, taxonomic value of thylakoid morphology seems very limited. Only special cases such as thylakoid absence or the parallel arrangement could be used as taxonomically informative apomorphies. The phylogenetic trees provide evidence of both paraphyly and reversion from more derived architectures in the simple parietal thylakoid pattern. Repeated convergent evolution is suggested for the radial and fascicular architectures. Moreover, thylakoid arrangement is constrained by cell size, excluding the occurrence of complex architectures in cyanobacteria smaller than 2 μm in width. It may further be dependent on unknown (eco)physiological factors as suggested by recurrence of the radial type in unrelated but morphologically similar cyanobacteria, and occurrence of special features throughout the phylogeny. No straightforward phylogenetic congruences have been found between proteins involved in photosynthesis and thylakoid formation, and the thylakoid patterns. Remarkably, several postulated thylakoid biogenesis factors are partly or completely missing in cyanobacteria, challenging their proposed essential roles.

/pdf/evolutionary-patterns-of-thylakoid-architecture-in-4pglaauwng.pdf

Evolutionary Patterns of Thylakoid Architecture in Cyanobacteria.

Diversity of cyanobacteria on stone monuments and building facades of India and their phylogenetic analysis

The author’s rights are protected under a Creative Commons AttributionNonCommercial 4.0 International (CC BY-NC 4.0) license. Citation:

/pdf/the-lampenflora-in-show-caves-and-its-treatment-an-emerging-1wz9x8a33q.pdf

The lampenflora in show caves and its treatment: an emerging ecological problem

A dry sample of Nostoc commune from an organic farm in Pingtung city (Taiwan) was used to prepare polysaccharide-rich (NCPS) extract. The conditioned medium (CM) from NCPS-treated human peripheral blood (PB)-mononuclear cells (MNC) effectively inhibited the growth of human leukemic U937 cells and triggered differentiation of U937 monoblast cells into monocytic/macrophagic lines. Cytokine levels in MNC-CMs showed upregulation of granulocyte/macrophage-colony stimulatory factor and IL-1β and downregulation of IL-6 and IL-17 upon treatment with NCPS. Moreover, murine macrophage RAW264.7 cells treated with NCPS exhibited the stimulatory effects of nitric oxide and superoxide secretion, indicating that NCPS might activate the immunity of macrophages. Collectively, the present study demonstrates that NCPS from N. commune could be potentially used for macrophage activation and consequently inhibited the leukemic cell growth and induced monocytic/macrophagic differentiation.

/pdf/immunomodulatory-potential-of-the-polysaccharide-rich-10r6qe2out.pdf

Immunomodulatory Potential of the Polysaccharide-Rich Extract from Edible Cyanobacterium Nostoc commune

This work characterizes a unicellular cyanobacterium with nearly spherical cells and thin-outlined sheaths that divide irregularly, forming small packets immersed in a diffluent mucilaginous layer. It was isolated growing on calcite speleothems and walls in a show cave in Collbato (Barcelona, Spain). Spectral confocal laser and transmission electron microscopy were used to describe the morphology, fine structure and thylakoid arrangement. The pigments identified were phycoerythrin, phycocyanin, allophycocyanin and chlorophyll a. Three-dimensional reconstructions, generated from natural fluorescence z-stacks, revealed a large surface area of nearly flat, arm-like thylakoidal membranes connected to each other and forming a unified structure in a way that, to our knowledge, has never been described before. Phylogenetic analyses using the 16S rRNA gene sequence showed 95 % similarity to strain 
Chroococcus
sp. JJCM (GenBank accession no. AM710384). The diacritical phenotypic features do not correspond to any species currently described, and the genetic traits support the strain being classified as the first member of an independent genus in the order Chroococcales and the family Chroococcaceae. Hence, we propose the name Chalicogloea cavernicola gen. nov., sp. nov. under the provisions of the International Code of Nomenclature for Algae, Fungi and Plants. The type strain of Chalicogloea cavernicola is COLL 3T ( = CCALA 975T  = CCAP 1424/1T).

Chalicogloea cavernicola gen. nov., sp. nov. (Chroococcales, Cyanobacteria), from low-light aerophytic environments: combined molecular, phenotypic and ecological criteria.

An aerophytic Nostoc, from a Mayan monument, has been characterized by phenotypic and molecular approaches, and identified as a morphospecies of Nostoc commune. Phylogenetic analysis indicates that it belongs to a Nostoc sensu stricto clade, which contains strains identified as N. commune. Nostoc cf. commune is found in two close areas: Site I (protected from direct sunlight by a wall), where it forms biofilms on mortar with Trentepohlia aurea; and Site II, where it grows on exposed stucco with the accompanying organism Scytonema guyanense. Over the year, in a habitat dictated by alternating wet and dry seasons, the organisms vary in appearance. Its life cycle comprises two seasonally-determined developmental stages (growth during the wet season and dormancy during the dry season) and two transitional stages (preparation for the dry season, and rehydration and recovery). At the beginning of the wet season the resistant stages from the previous dry season are rehydrated and form propagula, that adopt a colonial shape surrounded by a gelatinous sheath. As conditions become drier, clearly more in Site II, N. cf. commune employs adaptative strategies agains the drought, such as reducing the number of cells inside thick ensheathed colonies. Akinetes were observed, although only in Site II and in cultures of an isolated strain. Their fine structure shows parallel arrays of whorled thylakoids and septal intercellular connections. Spectral confocal laser scanning microscopy was used to analyze the fluorescence spectra of the photosynthetic pigments. N. cf. commune shows phycocyanin, allophycocyanin and chlorophyll a in both sites. Moreover, spectra of vegetative ensheathed cells, collected at Site II at the dry season, differed in their fluorescence spectrum: they feature a peak at 564 nm, attributed to phycoerythrin, which increases cell tolerance against the detrimental effects of strong light. These findings indicate that both the distribution and persistence of N. cf. commune might stem from cumulative adaptative strategies that increase its resistance to extreme desiccation.

/pdf/polyphasic-approach-and-adaptative-strategies-of-nostoc-cf-1mdizg382e.pdf

Polyphasic approach and adaptative strategies of Nostoc cf. commune (Nostocales, Nostocaceae) growing on Mayan monuments.

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Polyphasic approach and adaptative strategies of Nostoc cf. commune (Nostocales, Nostocaceae) growing on Mayan monuments.