Using metabarcoding to assess Viridiplantae sequence diversity present in Antarctic glacial ice

Antarctica contains most of the glacial ice on the planet, a habitat that is largely unexplored by biologists. Recent warming in parts of Antarctica, particularly the Antarctic Peninsula region, is leading to widespread glacial retreat, releasing melt water and, potentially, contained biological material and propagules. In this study, we used a DNA metabarcoding approach to characterize Viridiplantae DNA present in Antarctic glacial ice. Ice samples from six glaciers in the South Shetland Islands and Antarctic Peninsula were analysed, detecting the presence of DNA representing a total of 16 taxa including 11 Chlorophyta (green algae) and five Magnoliophyta (flowering plants). The green algae may indicate the presence of a viable algal community in the ice or simply of preserved DNA, and the sequence diversity assigned included representatives of Chlorophyta not previously recorded in Antarctica. The presence of flowering plant DNA is most likely to be associated with pollen or tissue fragments introduced by humans

Carta Editorial

Carta Editoria

Antioxidant activities of sulfated polysaccharides from brown and red seaweeds

The in vitro antioxidant activities of the following six sulfated polysaccharides were investigated: iota, kappa and lambda carrageenans, which are widely used in the food industry, fucoidan (homofucan) from the edible seaweed Fucus vesiculosus and fucans (heterofucans) F0.5 and F1.1 from the seaweed Padina gymnospora. With respect to the inhibition of superoxide radical formation, fucoidan had an IC50 (the half maximal inhibitory concentration) of 0.058 mg·mL−1, while the IC50 for the kappa, iota and lambda carrageenans were 0.112, 0.332 and 0.046 mg·mL−1, respectively. All of the samples had an inhibitory effect on the formation of hydroxyl radicals. The results of peroxidation tests showed that fucoidan had an IC50 of 1.250 mg·mL−1 and that the kappa, iota and lambda carrageenans had an IC50 of 2.753 and 2.338 and 0.323 mg·mL−1, respectively. Fucan fractions showed low antioxidant activity relative to fucoidan. These results clearly indicate the beneficial effect of algal polysaccharides as antioxidants

Taxithelium juruense (Broth.) Broth. (Pylaisiadelphaceae) an endangered Brazilian endemic, with notes on the genus Taxithelium in Brazil

(Taxithelium juruense (Broth.) Broth. (Pylaisiadelphaceae) an endangered Brazilian endemic, with notes on the genus Taxithelium in Brazil). Since its original description, several collections of this species were reported in different states of Brazil. During a revision of the genus, it was confirmed that the geographic range of this species is restricted to the state of Acre, all other reports being based on misidentifications due mostly to the highly polymorphic nature of Taxithelium planum (Brid.) Mitt. Here, we present a more detailed study of T. juruense with characters that will help to distinguish it from T. planum. The misidentifications have obscured the real conservation status of this species, which should be endangered (EN). Key and illustrations of the Brazilian species of Taxithelium are provided.Desde a sua descrição original diversas coletas têm sido reportadas para este táxon em diferentes estados brasileiros. Durante a revisão do gênero Taxithelium e o estudo do material tipo, comprovou-se que o táxon, é restrito ao estado do Acre, sendo as demais ocorrências baseadas em identificações errôneas, em especial, devido à natureza altamente polimórfica de Taxithelium planum (Brid.) Mitt. Neste trabalho, apresentamos um estudo mais detalhado de T. juruense com as características que o diferenciam de T. planum. As citações equivocadas têm ocultado o verdadeiro estado de conservação desta espécie que deveria ser de espécie ameaçada (EN). Chave e ilustrações para as espécies de Taxithelium do Brasil são apresentadas

Morphology and development of leaf papillae in the Pilotrichaceae

Sporophyte morphology has been traditionally used in taxonomic studies of pleurocarpous mosses. However, the gametophyte morphology of the Pilotrichaceae still holds interesting and under-investigated characters. Here, we conducted an in-depth investigation of the morphology and development of Pilotrichaceae leaf papillae and assessed their usefulness in inferring the evolutionary history of the family. Specimens were observed under scanning electron microscopy, and we identified seven morphological types of papillae, as well as two different pathways of development. Our results suggest that papilla morphology and development are phylogenetically informative in the Pilotrichaceae

The bryophytes of Trindade Island, South Atlantic, Brazil

Trindade is a Brazilian oceanic island located about 1,200 Km east of the Brazilian coast (between 20º 31' 30" S, 29º 19' 30'' W). The island originated from the abissal zone about 3 million years ago, has a maximum altitude of 620 meters and an area of 9.28 Km². Even though the fanerogamic flora is known, there were virtually no data on the bryophyte flora. Four expeditions to the island were carried out during two years and approximately 431 specimens collected. This work presents the Bryoflora of this island, which comprises 32 species, including 20 species of liverworts distributed among six families; the most speciose being Lejeuneaceae with 11 species and Frullaniaceae with four. There are also 11 species of mosses distributed among eight families, the most diverse being Fissidentaceae, Leocobryaceae and Pottiaceae with two species each. Only one species of hornworts was found. The bryophyte flora of Trindade most likely originated from the threatened Atlantic Forest of southeastern Brazil and, therefore, has conservation implications. Keys and comments are provided

Fairy ring disease affects epiphytic algal assemblages associated with the moss Sanionia uncinata (Hedw.) Loeske (Bryophyta) on King George Island, Antarctica

Since the nineteenth century, a ring-forming disease attacking Antarctic mosses has been reported. However, to date, only the effects on the mosses themselves are known. In this study, we used DNA metabarcoding to investigate the effects on the moss epiphytic algal community at different stages of disease progression. As the disease progressed, algal species richness decreased, although overall abundance was not significantly affected. Prasiolales appeared unaffected, whereas Ulotrichales were more sensitive. Trebouxiales dominated the advanced disease stage, suggesting a possible benefit from the disease, either through the elimination of competition or creation of new niches. Infection is responsible for moss death, leading to habitat loss for other organisms, but pathogenic effects on algae cannot be ruled out. Our data indicate that the disease not only impacts mosses but also other groups, potentially resulting in loss of Antarctic biodiversity. This study provides the first report of the disease effects on epiphytic algal communities of Antarctic bryophytes

Soil Fungal Diversity and Ecology Assessed Using DNA Metabarcoding along a Deglaciated Chronosequence at Clearwater Mesa, James Ross Island, Antarctic Peninsula

We studied the fungal diversity present in soils sampled along a deglaciated chronosequence from para- to periglacial conditions on James Ross Island, north-east Antarctic Peninsula, using DNA metabarcoding. A total of 88 amplicon sequence variants (ASVs) were detected, dominated by the phyla Ascomycota, Basidiomycota and Mortierellomycota. The uncommon phyla Chytridiomycota, Rozellomycota, Monoblepharomycota, Zoopagomycota and Basidiobolomycota were detected. Unknown fungi identified at higher hierarchical taxonomic levels (Fungal sp. 1, Fungal sp. 2, Spizellomycetales sp. and Rozellomycotina sp.) and taxa identified at generic and specific levels (Mortierella sp., Pseudogymnoascus sp., Mortierella alpina, M. turficola, Neoascochyta paspali, Penicillium sp. and Betamyces sp.) dominated the assemblages. In general, the assemblages displayed high diversity and richness, and moderate dominance. Only 12 of the fungal ASVs were detected in all chronosequence soils sampled. Sequences representing saprophytic, pathogenic and symbiotic fungi were detected. Based on the sequence diversity obtained, Clearwater Mesa soils contain a complex fungal community, including the presence of fungal groups generally considered rare in Antarctica, with dominant taxa recognized as cold-adapted cosmopolitan, endemic, saprotrophic and phytopathogenic fungi. Clearwater Mesa ecosystems are impacted by the effects of regional climatic changes, and may provide a natural observatory to understand climate change effects over time