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Microsatellites (SSRs) are tandem repeat sequences in eukaryote genomes, including plant cytoplasmic genomes. The mitochondrial genome (mtDNA) has been shown to vary in size, number, and distribution of SSRs among different plant groups. Thus, SSRs contribute with genomic diversity in mtDNAs. However, the abundance, distribution, and evolutionary significance of SSRs in mtDNA from a wide range of algae and plants have not been explored. In this study, the mtDNAs of 204 plant and algal species were investigated related to the presence of SSRs. The number of SSRs was positively correlated with genome size. Its distribution is dependent on plant and algal groups analyzed, although the cluster analysis indicates the conservation of some common motifs in algal and terrestrial plants that reflect common ancestry of groups. Many SSRs in coding and non-coding regions can be useful for molecular markers. Moreover, mitochondrial SSRs are highly abundant, representing an important source for natural or induced genetic variation, i.e., for biotechnological approaches that can modulate mtDNA gene regulation. Thus, this comparative study increases the understanding of the plant and algal SSR evolution and brings perspectives for further studies.

In Antarctica, fungi occupy different niches and interact with different living things; but its importance in these niches and interactions is still poorly understood. An example of an interaction reported from Antarctica involves fungi and the Antarctic mosses, in which the fungi formed rings on the carpets of mosses. However, due to the complexity of these fungi, information about these is limited, and they have not been completely characterized yet. The Antarctic region is vulnerable to climatic change, and abiotic factors can influence the growth of fungi. This may impact the pathogenic interactions between the mosses and the fungi. The aim of this study was to identify, characterize, and evaluate the pathogenic potential of a fungus isolated from moss samples Sanionia uncinata (Hedw.) Loeske. The material for this study was collected from King George Island during the Brazilian Antarctic Expedition XXXI. Through taxonomic, molecular, and phylogenetic methods, the isolate was identified as belonging to the genus Trichoderma. The isolate inhibited the growth of the moss Physcomitrium acutifolium Broth. in vitro and caused complete discolouration of its gametophytes. The physiological characterization of the isolate revealed that it was psychrotolerant with optimal growth at 20 °C, producing amylase and protease at temperatures of both 10 and 30 °C and cellulase at 10 °C only. These results suggest that an increase in temperature may enhance the occurrence of ring-forming fungi in mosses in Antarctica.

Background: Cooking quality is an important attribute in Common/Asian rice (Oryza sativa L.) varieties, being highly dependent on grain starch composition. This composition is known to be highly dependent on a cultivar’s genetics, but the way in which their genes express different phenotypes is not well understood. Further analysis of variation of grain quality genes using new information obtained from the wild relatives of rice should provide important insights into the evolution and potential use of these genetic resources.Findings: The analysis of the protein sequences of grain quality genes across the Oryza suggest that the deletion/mutation of amino acids in active sites result in variations that can negatively affect specific steps of starch biosynthesis in the endosperm. As observed in O. sativa subsp. japonica, the lower amylose content is probably related to the absence of a C-terminal domain in PUL, characterizing what we know as japonica genotypes. On the other hand, the complete deletion of some genes in the wild species do not affect the amylose content, as observed in the absence of GBSSII in starch biosynthesis of O. meridionalis, SSIV2 in O. glaberrima and DPE1 in O. brachyantha and O. nivara in which such modifications seem not to affect the final endosperm starch composition.Conclusion: Here we present new insights for obtaining new starch-specific rice phenotypes, considering structural protein features that include both the absence and duplication of copies, once again denoting that Oryza species are a rich source of variability for use in plant breeding.

This paper presents the details of lichens and mosses found on whale vertebrae substratum in the Admiralty Bay area, King George Island, Antarctica. Samples were taken in the coastal area at Hennequin Point, a relict of the Antarctic whaling era. The samples were collected from the upper surface of the whale bones found in the study area during the austral summer 2010–2011. A total of 15 lichen and two moss species were found. All species sampled are known in the Admiralty Bay area, both as pioneers and in more advanced succession stages in ice-free areas. These results suggest that the colonisation of whale bones is not new for Antarctic plants, but it is an additional substrate on which these plants can develop. A map showing the distribution of colonised bones and details of the usual substrata for the lichens and mosses found in this study are provided.

Endophyte biology is a branch of science that contributes to the understanding of the diversity and ecology of microorganisms that live inside plants, fungi, and lichen. Considering that the diversity of endolichenic fungi is little explored, and its phylogenetic relationship with other lifestyles (endophytism and saprotrophism) is still to be explored in detail, this paper presents data on axenic cultures and phylogenetic relationships of three endolichenic fungi, isolated in laboratory. Cladonia curta Ahti & Marcelli, a species of lichen described in Brazil, is distributed at three sites in the Southeast of the country, in mesophilous forests and the Cerrado. Initial hyphal growth of Xylaria spp. on C. curta podetia started four days after inoculation and continued for the next 13 days until the hyphae completely covered the podetia. Stromata formation and differentiation was observed, occurring approximately after one year of isolation and consecutive subculture of lineages. Phylogenetic analyses indicate lineages of endolichenic fungi in the genus Xylaria, even as the morphological characteristics of the colonies and anamorphous stromata confirm this classification. Our preliminary results provide evidence that these endolichenic fungi are closely related to endophytic fungi, suggesting that the associations are not purely incidental. Further studies, especially phylogenetic analyses using robust multi-locus datasets, are needed to accept or reject the hypothesis that endolichenic fungi isolated from Xylaria spp. and X. berteri are conspecific.

The establishment of diatom communities depends on environmental factors such as the type of substrate and geographic conditions that influence the dispersal processes of these organisms. The main goal of this study was to evaluate the similarity between diatom communities associated with the macroalgae Prasiola crispa(Lightfoot) Kützing in relation to spatial distance from six sampled sites located in the South Shetland Islands, Maritime Antarctica. The diatom flora associated with Prasiola crispawas represented by 23 species distributed in 15 genera. Pinnularia australoschoenfelderiZidarova, Kopalová & Van de Vijver, LuticolaaustroatlanticaVan de Vijver, Kopalová, S.A.Spaulding & Esposito, Luticolaamoena Van der Vijver, Kopalová, Zidarova & Levkov, Pinnularia austroshetlandica(Carlson) Cleve-Euler and Psammothidium papilio(D.E. Kellogg et al.) Kopalová & Zidarova were the most abundant species in our samples, which together represented 68% of the total number of individuals collected. There is a great similarity in composition and abundance of the diatom community among the sampled points., which resulted in the absence of a linear pattern of relationship with the distance between sampling points. We conclude that distance was not a factor of differentiation of Antarctic diatom communities associated with terrestrial green macroalgae. Suggesting that Antarctic environments may have unique characteristics with homogeneous abiotic factors, at least related to this substrate.

Prasiola crispa is a macroscopic green algae found in abundance in Antarctica ice free areas. Prasiola crispan-hexaneextract (HPC) induced insecticidal activity in Nauphoeta cinerea cockroaches after 24 h of exposure. The chemical analysis of HPC revealed the presence of the followingphytosterols: β-sitosterol, campesterol and stigmasterol. The incubation of cockroach semi-isolated heart preparations with HPC caused a significant negative chronotropic activity in the heartbeats. HPC affected the insect neuromuscular function by inducing a complete inhibition of the cockroach leg-muscle twitch tension. When the isolated phytosterols were injected at in vivo cockroach neuromuscular preparations, there was a progressive inhibition of muscle twitches on the following order of potency: β-sitosterol > campesterol > stigmasterol. HPC also provoked significant behavioral alterations, characterized by the increase or decrease of cockroach grooming activity, depending on the dose assayed. Altogether, the results presented here corroborate the insecticide potential of Prasiola crispa Antarctic algae. They also revealed the presence of phytosterols and the involvement of these steroidal compounds in the entomotoxic activity of the algae, potentially by modulating octopaminergic-cholinergic pathways. Further phytochemical-combined bioguided analysis of the HPC will unveil novel bioactive compounds that might be an accessory to the insecticide activity of the algae.

The ability of bryophytes to tolerate salt is determined by a number of biochemical routes, whereas the salt ends up driving the activation of adaptive responses to tolerate this adverse condition. Salinity is the main limiting environmental factor under plant development, and is caused by excess salt ions in the environment, mainly Na + and Cl-. The optimal growth of plants in saline environment is obtained in concentrations of 50% of NaCl. Due to these findings, the importance of the study of the effect of salinity on the germination of plants, in this case in Funaria hygrometrica Hedw., is noticed. A capacidade das briófitas para tolerar meios salinos é determinada por uma série de vias bioquímicas, uma vez que o sal acaba por conduzir a ativação de respostas adaptativas para tolerar esta condição adversa.A salinidade é o principal fator ambiental limitante no desenvolvimento da planta e é causada pelo excesso de íons salinos no ambiente, principalmente Na+ e Cl-. O crescimento ótimo de plantas em ambiente salino foi obtido em concentrações de 50% de NaCl. Devido a essas descobertas esses achados, observa-se a importância do estudo do efeito da salinidade sobre a germinação de plantas, neste caso em Funaria hygrometrica Hedw.

Pleurotus spp. are considered extremely rich mushroom species from the nutritional pointof view, providing immune-enhancement effects when consumed. However, few mushroomshave been tested for their phenotypic and genotypic responses in animal modelsto ensure the proper dosage for their use. This study aimed to evaluate the effects of twomushroom species on the reproductive capacity of Drosophila melanogaster . Pleurotuscitrinopileatus Singer and Lentinus sajor-caju (Fr.) Fr. were provided separately, in specificconcentrations, as feed supplements to the fruit flies. The total numbers of developedlarvae, pupae, and adults were then measured for each treatment. Inter simple sequencerepeats marker analysis was carried out to infer genotypic changes in the mushroom-fedflies. Our results suggest that Pleurotus spp. can cause positive changes to the flies’ reproductivecapacity, since Pleurotus citrinopileatus in particular accelerated the life cycle andrevealed a higher genetic dissimilarity of the diet-supplemented flies. Keywords: fruitflies, reproductive fitness, edible mushrooms.

In the current study, we present the molecular characterization of an endophyte fungus associated with the leaves of Deschampsia antarctica Desv. (Poaceae), a monocot species native to Antarctica. The isolate was obtained from 90 leaf fragments from two distinct collection sites, both located on Half Moon Island, South Shetland Islands and Maritime Antarctica. The internal transcribed spacer region (ITS) was sequenced and the endophytic fungus was identified as belonging to the genus Juncaceicola Tennakoon, Camporesi, Phook and K.D. Hyde (99% nucleotide sequence identity). When compared to all fungi of the genus Juncaceicola deposited in data base, our isolate showed greater proximity with Juncaceicola typharum, however, because it presents a low bootstrap value to be considered a new species, we treat it as Juncaceicola cf. typharum. Moreover, the identification of our isolate as belonging to the genus Juncaceicola makes this the first occurrence of a species of this genus to be associated with the leaves of Antarctic plants. This work is considered as a starting point for other studies with fungi of this genus associated with leaves of Deschampsia antarctica, as it presents results from two collection points on a single Antarctic island, suggesting that new sites and new Antarctic islands should be explored.

In this study, the organelle genomes of Polytrichum juniperinum Hedw. and Polytrichum strictum Menzies ex Brid. (Polytrichaceae, Bryophyta) from Antarctica were sequenced and compared with the plastomes of the model moss species Physcomitrella patens Brid. The sizes of the cpDNA in P. juniperinum and P. strictum were estimated to be 55,168 and 20,183 bp, respectively, the sizes of the mtDNA were 88,021 and 58,896 bp, respectively. The genomes are very similar to each other, with the possible loss of petN in the cpDNA, which also showed some gene inversions when compared with the cpDNAs of P. patens Brid. In the mtDNA, it is possible that rps10 was lost. In contrast, Antarctic Polytrichaceae species have nad7 and orf187, without the occurrence of rearrangement events. Phylogenomic analyses of the plastid and mitochondria revealed that the majority-rule tree suggests some differences in the plastids ancestry, however, P. juniperinum and P. strictum were grouped in the same clade in chloroplast, but in mitochondria P. strictum was grouped with Atrichum angustatum (Brid.) Bruch &amp, Schimp. This study helped us understand the evolution of plastomes and chondriosomes in the family Polytrichaceae, and suggest a hybridization event with relation to the mitochondrial data.

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The Antarctic lichens have been used as bioindicators in biomonitoring studies, having an important contribution to the floristic composition, and its existence is dependent on ice-free regions. The phytosociological data were obtained according to the Braun-Blanquet sampling method. This study compares the lichen formation of Arctowski region, using data collected during the Brazilian Antarctic Program expedition conducted in the austral summer of 2003/2004 and 2012/2013. According to data collected at the moment, increases of the lichens occurrences in the plant formations in the region were found. Studies indicate that abiotic factors, once linked to local factors can to affect the distribution of the communities in the environment. This essay suggests the fragility of lichen formation in the ice-free areas of Arctowski region. However, a long term evaluation as necessary to confirm this hypothesis. The phytosociological studies can contribute to the management of scientific activities involved with the Brazilian Antarctic Program.

Humans distribute a wide range of microorganisms around building interiors, and some of these are potentially pathogenic. Recent research established that humans are the main drivers of the indoor microbiome and up to now significant literature has been produced about this topic. Here we analyzed differences in bacterial composition between men's and women's restrooms and other common areas within the same public building. Bacterial DNA samples were collected from restrooms and halls of a three-floor building from the Federal University of Pampa, RS, Brazil. The bacterial community was characterized by amplification of the V4 region of the 16S rRNA gene and sequencing. Throughout all samples, the most abundant phylum was Proteobacteria, followed by Actinobacteria, Bacteroidetes and Firmicutes. Beta diversity metrics showed that the structure of the bacterial communities were different among the areas and floors tested, however, only 6-9% of the variation in bacterial communities was explained by the area and floors sampled. A few microorganisms showed significantly differential abundance between men's and women's restrooms, but in general, the bacterial communities from both places were very similar. Finally, significant differences among the microbial community profile from different floors were reported, suggesting that the type of use and occupant demographic within the building may directly influence bacterial dispersion and establishment.

The genus Cystolepiota , which belongs to the family Agaricaceae, is differentiated from the other genera of the family mainly because it has a white to cream print spore and the cortical layer of the pileus is constituted by spherical cells, usually organized in short to long chains, the pileus surface being strongly pulverulent in some species. This paper presents the study of 14 species of Cystolepiota , cited for Brazil and Tucuman, Argentina, which was based on herbarium specimens and literature available about the South American mycobiota. Seven species, namely C. albogilva Singer, C. amazonica Singer, C. marthae Singer, C. potassiovirens Singer, C. seminuda (Lasch) Bon, C. sistrata (Fr.) Singer ex Bon and Bellu and C. violaceogrisea (Rick) Singer, have been cited for Brazil. Five species, viz. C. australis Singer, C. adulterina (F.H. Moller) Bon, C. brunneotingens Sing, C. constricta Singer and C. rubra Singer, were cited only for Argentina. In addition, C. rosea Singer was cited for Argentina and Chile and C. luteifolia Singer was described from Peru. Illustrations of micro-morphological features are presented for these species and an artificial key for species identification, based on examined specimens and in the original description, is provided. Keywords: Agaricomycetes, Agaricaceae, taxonomy, diversity.

The adverse effects of the alga Prasiola crispa extract (PcE) were investigated in a fruit fly (Drosophila melanogaster) and cockroach (Nauphoeta cinerea) model. In flies, toxicity was assessed as mortality and biochemical alterations including acetylcholinesterase (AChE) activity and oxidative stress markers. The cardiotoxic action of PcE was also examined in a model of semi-isolated cockroach heart. The administration of PcE (2 mg/ml) to flies for 24 h resulted in a marked increase in mortality rate (7.6-fold rise compared to control). AChE activity, glutathione (GSH) levels, and hydroperoxide formation remained unchanged. Fly glutathione S-transferase (GST) and catalase (CAT) activity were significantly altered after PcE treatment. Fraction III (ethyl acetate) of PcE was significantly more toxic to flies compared to fractions I (methanol) and II (ethanol). A significant decrease was noted in cockroach semi-isolated heart function. The addition of 5,5'-dithiobis-(2-nitrobenzoic acid (DTNB), an oxidizing agent, concomitant with the extract significantly blocked this effect, suggesting that reduced compounds may be involved in the cardiotoxic action produced by PcE. Our results show for the first time the adverse effects of PcE in two insect models, Drosophila melanogaster and Nauphoetacinerea. The insecticidal properties of PcE may be related to changes in important antioxidant/detoxifying systems, as well as to changes in insect cardiac function.

King George Island is the largest island and the principal area used for research bases in Antarctica. Argentina, Brazil, Chile, China, Poland, Russia, South Korea and Uruguay have permanent open bases on this island. Other countries have seasonal summer stations on different parts of this island, which demonstrates that human impact is strong on King George Island relative to other areas in the maritime and continental Antarctica. The objective of this work was to present a phytosociological approach for ice-free areas of Hennequin Point, eastern coast of Admiralty Bay, King George Island. The study started with the classification and description of the plant communities based primarily on phytosociological and biodiversity data. The area was mapped using an Astech Promark II® DGPS, yielding sub-metric precision after post-processing with software. The plant communities were described as follows: (1) lichen and moss cushion formation; (2) moss carpet formation; (3) fellfield formation; (4) grass and cushion chamaephyte formation; and (5) Deschampsia Antarctica– lichen formation. Characterizations and distributions of the plant communities are presented on a map at a scale of 1:5000. The plant communities found at Hennequin Point, in general, differ from those found in other areas of the Admiralty Bay region, probably because of the concentration of skua nests in the area and the relief singularities. We conclude by highlighting the importance of the study of plant species found in the ice-free areas of the Antarctic with respect to environmental monitoring and for evaluating global climate and environmental changes. Keywords: Plant communities mapping; lichens; mosses; flowering plants; Antarctic (Published: 7 August 2013) Citation: Polar Research 2013, 32 , 19261, http://dx.doi.org/10.3402/polar.v32i0.19261

Angiosperms are the most diverse and numerous group of plants, and it is generally accepted that this evolutionary success owes in part to the diversity found in fruits, key for protecting the developing seeds and ensuring seed dispersal. Although studies on the molecular basis of morphological innovations are few, they all illustrate the central role played by transcription factors acting as developmental regulators. Here, we show that a small change in the protein sequence of a MADS-box transcription factor correlates with the origin of a highly modified fruit morphology and the change in seed dispersal strategies that occurred in Medicago, a genus belonging to the large legume family. This protein sequence modification alters the functional properties of the protein, affecting the affinities for other protein partners involved in high-order complexes. Our work illustrates that variation in coding regions can generate evolutionary novelties not based on gene duplication/subfunctionalization but by interactions in complex networks, contributing also to the current debate on the relative importance of changes in regulatory or coding regions of master regulators in generating morphological novelties., Spanish Ministerio de Ciencia e Innovación (grant no. BIO2009–09920 to C.Fe.), the European Union (grant no. FP7–PEOPLE–PIRSES–2009–247589 to C.Fe. and A.C.d.O.), and a Fellowship for Foreign Young Postdocs from the Spanish Ministerio de Ciencia e Innovación (to C.Fo.).

The study aimed at to determine the magnitude of the methane (CH 4 ) and nitrous oxide (N 2 O) flux rates in soils at Hennequin Point, King George Island, Antarctic, under different slope positions, vegetal covers and presence of skuas, as well as to evaluate the main soil and climate factors that are involved with the flux of such gases. In situ gas sampling (closed chamber method) was performed in four sites along a transect involving a skua nesting field in a moraine with 5% and 100% of surface covered by vegetal, and two poor-drained soils in the toeslope (a bare alluvium soil and a poor-drained moss field with 100% soil cover). Flux rates ranged from −0.86 ± 0.45 to 2.75 ± 1.52 μg N 2 O–N m −2 h −1 and −12.26 ± 3.05 to 1.42 ± 1.31 μg CH 4 –C m −2 h −1 . The soil totally covered by vegetal in the skua field had the largest CH 4 influx rates. However, this benefic effect was counterbalanced by the greatest N 2 O efflux rates from this soil, resulting in the largest contribution to the global warming potential among the soils evaluated. Flux rates were closely related to soil temperature, but no significant relation was observed with mineral N contents and water-filled pore space. In turn, accumulated CH 4 and N 2 O emissions were closely related to the total N and total organic C stocks in the soil. Net CH 4 influx predominated even in the poor-drained soils, suggesting that the coarse soil texture avoided critical anaerobic conditions. No significant changes in flux rates were observed for sampling time along the day.

This work reports the occurrence of fungi species of the genera Chlorophyllum Massee and Macrolepiota Singer, the latter not yet registered for Sao Gabriel, Rio Grande do Sul state, Brazil. The study area is located in the Pampa biome, being the samplings conducted between April 2011 and May 2012. The micobiota studied in the area is represented until this moment by five species, as follows: Macrolepiota gracilenta (Krombh) Wasser, Macrolepiota fuligineosquarrosa Malencon, Macrolepiota procera (Scop.) Singer, Chlorophyllum rachodes (Vittad.) Vellinga and Chlorophyllum molybdites (G. Mey.) Massee. Identification keys for these species and two new occurrences of Macrolepiota for, respectively, Brazil and Rio Grande do Sul, are presented.Keywords: mycodiversity, taxonomy, Basidiomycota.

Antarctica is one of the most difficult habitats for sustaining life on earth; organisms that live there have developed different strategies for survival. Among these organisms is the green alga Prasiola crispa, belonging to the class Trebouxiophyceae. The literature on P. crispa taxonomy is scarce, and many gaps in the evolutionary relationship with its closest relatives remain. The goal of this study was to analyze the evolutionary relationships between P. crispa and other green algae using plastid and mitochondrial genomes. In addition, we analyzed the synteny conservation of these genomes of P. crispa with those of closely related species. Based on the plastid genome, P. crispa grouped with Prasiolopsis sp. SAG 84.81, another Trebouxiophyceaen species from the Prasiola clade. Based on the mitochondrial genome analysis, P. crispa grouped with other Trebouxiophyceaen species but had a basal position. The structure of the P. crispa chloroplast genome had low synteny with Prasiolopsis sp. SAG 84.81, despite some conserved gene blocks. The same was observed in the mitochondrial genome compared with Coccomyxa subellipsoidea C-169. We were able to establish the phylogenetic position of P. crispa with other species of Trebouxiophyceae using its genomes. In addition, we described the plasticity of these genomes using a structural analysis. The plastid and mitochondrial genomes of P. crispa will be useful for further genetic studies, phylogenetic analysis and resource protection of P. crispa as well as for further phylogenetic analysis of Trebouxiophyceaen green algae.

Here, we present a draft genome and annotation of Rhodococcus rhodochrous TRN7, isolated from Trindade Island, Brazil, which will provide genetic data to benefit the understanding of its metabolism.

We investigate the plant composition in the Skuas nest at Hennequin Point, located in the Admiralty Bay Area, King George Island, Antarctica. Sample of 61 activity nests were analyzed. 21 plant and lichenized fungi species were found in the nest composition, being the mosses Sanionia uncinata (Hedw.) Loeske and Polytrichastrum alpinum (Hedw.) G. S. Smith the most frequent species found in the Skuas nests. Usnea antarctica Du Rietz was the most frequent lichen and the grass Deschampsia antarctica Desv was the most frequent flowering plant found in the nests. These results contribute for the environmental menagement of the Admiralty Bay area research activities.

This study was undertaken in ice-free areas adjacent to the Polish Antarctic Station Henryk Arctowski, during the austral summer 2013/2014. Phytossociological surveys were made in vegetation patches in the region, where a total of 332 20x20cm quadrats were launched in 10m transects. The five most frequent species in the samples were selected and their data are presented in this work. To check the most frequent species in the samples the index of ecological significance (IES) was used. The most important species were Deschampsia antarctica Desv. and Colobanthus quitensis (Kunth) Bartl the only one angiosperms occurring in Antarctica. Sanionia uncinata (Hedw.) Loeske Politrichastrum alpinum (Hedw.) G.L.Sm. and Syntrichia magellanica (Mont.) R.H. Zander. were the most representative moss species. The data of ecological significance of these species were compared to previous results in order to evaluate the changes in the vegetation in 10 year long-time monitoring.

The distribution of fungi in Antarctica is linked to the distribution of hosts such as birds, invertebrate populations and vegetation, consisting mainly of bryophyte and lichen communities. Light is a factor which influences the growth, reproduction and physiology of fungi due to the deleterious effects of radiation released. This study aimed to evaluate the influence of light on radial mycelial growth of two species of filamentous fungi found in Antarctica: Pseudogymnoascus pannorum (Link) Minnis & D.L. Lindner and an unidentified strain growing over angiosperm Colobanthus quitensis (Kunth) Bartl. and on the moss Sanionia uncinata (Hedw.) Loeske, respectively. The collections of material for this study were conducted during the Brazilian Antarctic expedition XXXI (2012-2013). The strains were isolated in solid potato dextrose agar medium, with pH adjusted to 4 and incubated at 26±1°C. Statistical results show that the variable light influences the radial mycelial growth of these fungi.

The aim of this study has been to research the conservation status of the plant communities in ice-free areas of Ullmann Point and Comandante Ferraz Antarctic Station vicinities, Admiralty Bay, King George Island, Antarctica. The study started with the classification and description of the plant communities based primarily on phytosociological and biodiversity data. The coverage degree and frequency of each species found was used to calculate the index of ecological significance. At Ullmann Point 12 plant species were found in higher frequency, when at Ferraz beach only 9 highly frequent species were found. The most important species in both studied areas were Sanionia uncinata (Hedw.) Loeske. Syntrichia princeps and Bryum pseudotrichetrum were found associated with the most important species at Ullmann Point and Ferraz Station beach respectively. These results have demonstrated the fragility of plant communities in Maritime Antarctica, based on the low frequency and coverage of moss species known in this area.

The organelle genomes of the Antarctic alga Prasiola crispa (Lightfoot) Kützing have been sequenced. The plastid and mitochondrial genomes have a total length of 196,502 bp and 89,819 bp, respectively. These genomes have 19 putative photosynthesis-related genes and 17 oxidative metabolism-related genes, respectively.

Studies on phenotypic variation among populations growing in different microenvironments may provide information about plasticity related to environmental pressures, and thus help to elucidate the potential evolutionary forces contributing to the origin and maintenance of diversity in any region. In this study we investigate morphometric variation on a small geographic scale for three species of Antarctic mosses. All species revealed significant differentiation among populations for all evaluated traits. The comparison of morphometric measures of populations of Polytrichum juniperinumfrom Nelson Island and from southern Brazil suggests that the effects of a small geographic scale in Antarctica are the same as a large geographic scale in environments where the climate is more homogeneous and microhabitats have minor influence on vegetation. However, further investigations over a larger area, evaluating more species, and using controlled garden experiments are recommended in order to evaluate the capacity for plasticity of moss species in different climatic conditions and on different geographic scales.

This study aimed to quantify the nitrous oxide (N 2 O) and methane (CH 4 ) fluxes at sites with different vegetation covers and where bird activity was present or absent using the static chamber method, on Rip Point, Nelson Island, maritime Antarctic. The sites were soils covered by Sanionia uncinata , lichens, Prasiola crispa , Deschampsia antarctica and bare soil. Seabirds used the P. crispa and D. antarctica sites as nesting areas. Soil mineral N contents, air and soil temperature and water-filled pore space were measured, and the content of total organic C and particulate organic C, total N, bulk density and texture were determined to identify controlling variables of the gas emissions. The N 2 O and CH 4 flux rates were low for all sampling events. Mean N 2 O flux rates ranged from 0.11±1.93 up to 21.25±22.14 µg N 2 O m −2 h −1 for the soils under lichen and P. crispa cover, respectively. For the CH 4 fluxes, only the P. crispa site showed a low positive mean (0.47±3.61 µg CH 4 m −2 h −1 ). The bare soil showed the greatest absorption of CH 4 (−11.92±5.7 µg CH 4 m −2 h −1 ), probably favoured by the coarse soil texture. Bare soil and S. uncinata sites had N 2 O accumulated emissions close to zero. Net CH 4 accumulated emission was observed only at the P. crispa site, which was correlated with ( p< 0.001). These results indicate that seabird activity influences N 2 O and CH 4 soil fluxes, while vegetation has little influence, and bare soil areas in maritime Antarctica could be greenhouse gas sinks. Keywords : Soil greenhouse gases; seabirds; vegetal cover; maritime Antarctica. (Published: 3 February 2015) Citation: Polar Research 2015, 34 , 23584, http://dx.doi.org/10.3402/polar.v34.23584