Six strains of Cyanobacteria sampled in the Brazilian Atlantic rainforest and one strain from Kauai, Hawaii, were studied using morphological and molecular approaches, including 16S rRNA gene phylogenies and 16S-23S ITS secondary structures, and are herein described as Komarekilla atlantica gen. et sp. nov.. Morphologically they are similar to Nostoc, Desmonostoc, Halotia, and Mojavia and indistinguishable from Chlorogloeopsis. The parsimony and Bayesian phylogenies of the 16S rDNA show that these strains are close to nostocacean strains, in strongly supported clades and separated from all other genera. The secondary structures of the 16S-23S ITS were very consistent between strains of K. atlantica, but distinctly different from structures in other close taxa. Of special note, the Hawaiian strain of K. atlantica had 16S sequence identities of 99.5-100% to the Brazilian strains, and 16S-23S ITS sequence identities of 99.4-99.8% to the Brazilian strains, and consequently likely represents a very recent introduction of the species to Kauai from South America, the geographic source of many of the non-native plants in the Hawaiian Archipelago.

Nostoc is a common and well-studied genus of cyanobacteria and, according to molecular phylogeny, is a polyphyletic group. Therefore, revisions of this genus are urged in an attempt to clarify its taxonomy. Novel strains isolated from underexplored environments and assigned morphologically to the genus Nostoc are not genetically related to the 'true Nostoc' group. In this study, four strains isolated from biofilms collected in Antarctica and five strains originated from Brazilian mangroves were evaluated. Despite their morphological similarities to other morphotypes of Nostoc, these nine strains differed from other morphotypes in ecological, physiological and genetic aspects. Based on the phylogeny of the 16S rRNA gene, the Antarctic sequences were grouped together with the sequences of the Brazilian mangrove isolates and Nostoc sp. Mollenhauer 1 : 1-067 in a well-supported cluster (74 % bootstrap value, maximum-likelihood). This novel cluster was separated phylogenetically from the 'true Nostoc' clade and from the clades of the morphologically similar genera Mojavia and Desmonostoc. The 16S rRNA gene sequences generated in this study exhibited 96 % similarity to sequences from the nostocacean genera mentioned above. Physiologically, these nine strains showed the capacity to grow in a salinity range of 1-10 % NaCl, indicating their tolerance of saline conditions. These results provide support for the description of a new genus, named Halotia gen. nov., which is related morphologically to the genera Nostoc, Mojavia and Desmonostoc. Within this new genus, three novel species were recognized and described based on morphology and internal transcribed spacer secondary structures: Halotia branconii sp. nov., Halotia longispora sp. nov. and Halotia wernerae sp. nov., under the provisions of the International Code of Nomenclature for Algae, Fungi and Plants.

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Two species of heterocytous cyanobacteria from the Mata Atlântica of Southeastern Brazil were studied intensively to determine if they were congeneric or belong to different genera. Additionally, their affinity to established genera in the Tolypothricaceae such as Tolypothrix Bornet & Flahault, Hassallia Bornet & Flahault and Spirirestis Flechtner & Johansen was investigated.  Dapisostemon apicaliramis gen. et sp. nov. isolated from a wooden bridge in a mangrove swamp was found to be basal to a clade containing Tolypothricaceae, Nostocaceae, and Aphanizomenonaceae (but with weak support) by means of 16S rRNA gene sequence analyses. Moreover, D. apicaliramis had a 16S-23S ITS region similar in length, sequence, and secondary structure to the members of the terrestrial Tolypothricaceae. Streptostemon Sant’Anna et al. was placed in the Microchaetaceae (now the Tolypothricaceae) at the time of its description based on unsequenced natural material, but in this study it was found to be even more phylogenetically distant from that clade than Dapisostemon based on 16S rRNA gene sequence. It is in an unsupported and unresolved basal position in the Nostocales. It also presents a unique 16S-23S ITS region. The higher level evolutionary relationships of both genera are uncertain at this time, but neither genus can remain in the Microchaetaceae or Tolypothricaceae as the Nostocales undergo future revision.  We conclude that Dapisostemon is sufficiently unique and separate that it requires a new family, the Dapisostemonaceae. This study further demonstrates that the cyanobacteria of tropical regions often represent novel taxa in unstudied lineages and that the study of tropical cyanobacteria will yield new insights in the biodiversity of this ecologically important group of photosynthetic microorganisms.

Abstract:Members of the genus Scytonema belong to prominent components of microflora of tropical and subtropical soils, but their diversity and taxonomic classification is still little known. Molecular analyses of isolated strains, but also the morphological and ecological examination of natural populations are important for the starting revisions. Here we present phenotype characteristics of fourteen morphotypes of the cyanobacterial genus Scytonema from the SE Brazil, mostly from the state São Paulo and from the Atlantic Rainforest (ecosystem of "Mata Atlântica"). The populations of studied Scytonema species are ecologically significant, as they hold the dominant position in the microvegetation communities of lateritic and forest soils and of stony substrates (less frequently also aquatic forms). Species commonly distributed throughout the tropical regions (such as S. guyanense, S. javanicum, S. stuposum), as well as the types with restricted geographic distribution in S America are included in the study. Two new species from a little known subgenus Myochrotes, in which the cultivation is difficult, are described: S. papillicapitatum Sant´anna et KomáreK and S. chorae Sant´anna et KomáreK. Our analyses support the principle of congruency of morphological characters with phylogenetic position of the studied species.

The taxonomy of four isolated strains of Anabaenopis elenkinii and A. arnoldii from North and South America were investigated using a polyphasic approach. The studied populations were collected from seven alkaline lakes of the Brazilian Pantanal and Nabor Carrillo Lake, Texcoco region (Mexico), between 2004 and 2012, where they frequently formed blooms during the dry season. The morphological plasticity of the populations, from natural and culture conditions, was described based on 200 individuals of each species. The 16S rRNA and the cpc-BA-IGS phylogenetic analyses show Anabaenopsis as a sister-taxon of Cyanospira. The Anabaenopsis clade has three strongly supported subclusters related to the origin of strains: Pantanal+Mexico, Kenya+Australia and one European clade. Although these data indicate that the currently known Anabaenopsis strains belong to more than one species, we are being conservative and not describing them as new species due to the lack of more molecular data. We highlight the need of a revision of the genus, considering also that Anabaenopsis sp. PCC 9215, the current reference strain used for the genus, is not identified as A. elenkinii and it is phylogenetically grouped with Anabaenopsis strains identified as A. circularis, A. arnoldii, A. nadsonii and A. elenkinii.

Lyngbya C. Agardh ex Gomont is a nonheterocytous cyanobacterial genus whose evolutionary history is still poorly known. The traditionally defined Lyngbya has been demonstrated to be polyphyletic, including at least five distinct clades, some of which have been proposed as new genera. Intraspecific diversity is also clearly underestimated in Lyngbya due to the lack of unique morphological characters to differentiate species. In this study, we describe the new genus Capillus T. A. Caires, C. L. Sant'Anna et J. M. C. Nunes from benthic marine environments, including two new Brazilian species (here described as C. salinus T. A. Caires, C. L. Sant'Anna et J. M. C. Nunes, and C. tropicalis T. A. Caires, C. L. Sant'Anna et J. M. C. Nunes), and two species yet to be described, one of them from India (Capillus sp. 2.1), and the other from United States of America, based on strain PCC 7419. Capillus species presented crosswise diagonal fragmentation, assisted or not by necridic cells, which has not been previously mentioned for Lyngbya. Ultrastructural analyses showed that C. salinus and C. tropicalis have numerous gas vesicles, which are rarely described for benthic marine species. The new genus formed a well-supported clade, and the D1-D1′ and Box B secondary structures of internal transcribed spacer also supported the proposal of its new species. These findings help to clarify the diversity of species in the Lyngbya complex and the taxonomy of the group, and highlight the need of further floristic surveys in tropical coastal environments, which remain poorly studied.

Objective:The aim of the study was to assess, in vitro, the influence on cytotoxicity of heat treatment applied before photopolymerization, while mixing three self-adhesive resin cements, in an NIH/3T3 fibroblast cell culture, based on cell viability measures.Methods:Samples were divided into three groups: (1) no heat treatment while mixing (control), (2) 37°C, and (3) 60°C heat treatment while mixing. Cements were light-cured immediately after mixing and immersed in Dulbecco's Modified Eagle Media for the extraction of possibly uncured products after 24 h and 7 days. Cultures contained 0.5 mL of NIH/3T3 fibroblasts per well at a concentration of 0.4 × 105 cells/mL and specific extracts for each sample.Statistical Analysis Used:Data were statistically analyzed with ANOVA and post hoc Student–Newman–Keuls (significance of 5%).Results:Cement cytotoxicity increased with time, as shown by the higher values observed at 7 days. There was a slight difference in intragroup cytotoxicity levels between 24 h and 7 days. Heat treatment at 60°C was associated with a major decrease in cytotoxicity levels in all three groups, both at 24 h and at 7 days, with no differences among the cements.Conclusions:Heat treatment at 60°C should be considered as a strategy to reduce cytotoxicity of self-adhesive resin cements, as evidenced by the results observed at 24 h and 7 days of analysis.