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1.
Pol J Microbiol ; 68(4): 527-539, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31880896

RESUMO

Ulleungdo and Dokdo are volcanic islands with an oceanic climate located off the eastern coast of South Korea. In the present study, we used barcoded Illumina MiSeq to analyze eukaryotic microalgal genera collected from Seonginbong, the highest peak on Ulleungdo, and from groundwater sites on Dongdo and Seodo Islands, which are part of Dokdo. Species richness was significantly greater in the Seonginbong samples than in the Dongdo and Seodo samples, with 834 operational taxonomic units (OTUs) identified from Seonginbong compared with 203 OTUs and 182 OTUs from Dongdo and Seodo, respectively. Taxonomic composition analysis was also used to identify the dominant microalgal phyla at each of the three sites, with Chlorophyta (green algae) the most abundant phyla on Seonginbong and Dongdo, and Bacillariophyta (diatoms) the most abundant on Seodo. These findings suggest that differences in the abundances of Chlorophyta and Bacillariophyta species in the Seonginbong, Dongdo, and Seodo samples are due to variations in species richness and freshwater resources at each sampling location. To the best of our knowledge, this is the first report to detail freshwater microalgal communities on Ulleungdo and Dokdo. As such, the number of species identified in the Seonginbong, Dongdo, and Seodo samples might be an indicator of the ecological differences among these sites and varying characteristics of their microbial communities. Information regarding the microalgal communities also provides a basis for understanding the ecological interactions between microalgae species and other eukaryotic microorganisms.Ulleungdo and Dokdo are volcanic islands with an oceanic climate located off the eastern coast of South Korea. In the present study, we used barcoded Illumina MiSeq to analyze eukaryotic microalgal genera collected from Seonginbong, the highest peak on Ulleungdo, and from groundwater sites on Dongdo and Seodo Islands, which are part of Dokdo. Species richness was significantly greater in the Seonginbong samples than in the Dongdo and Seodo samples, with 834 operational taxonomic units (OTUs) identified from Seonginbong compared with 203 OTUs and 182 OTUs from Dongdo and Seodo, respectively. Taxonomic composition analysis was also used to identify the dominant microalgal phyla at each of the three sites, with Chlorophyta (green algae) the most abundant phyla on Seonginbong and Dongdo, and Bacillariophyta (diatoms) the most abundant on Seodo. These findings suggest that differences in the abundances of Chlorophyta and Bacillariophyta species in the Seonginbong, Dongdo, and Seodo samples are due to variations in species richness and freshwater resources at each sampling location. To the best of our knowledge, this is the first report to detail freshwater microalgal communities on Ulleungdo and Dokdo. As such, the number of species identified in the Seonginbong, Dongdo, and Seodo samples might be an indicator of the ecological differences among these sites and varying characteristics of their microbial communities. Information regarding the microalgal communities also provides a basis for understanding the ecological interactions between microalgae species and other eukaryotic microorganisms.


Assuntos
Microalgas/isolamento & purificação , Clorófitas/classificação , Clorófitas/genética , Diatomáceas/classificação , Diatomáceas/genética , Diatomáceas/isolamento & purificação , Água Doce/análise , Ilhas , Microalgas/classificação , Microalgas/genética , Filogenia , Análise de Sequência de DNA
2.
Mar Pollut Bull ; 145: 105-117, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31590766

RESUMO

The Beagle Channel is a remote subantarctic environment where mussel aquaculture initiatives have existed since the early 1990s. Here we analyze phytoplankton biomass and composition, and the occurrence of harmful microalgae species and their toxins at three sites during the period 2015-2016. The occurrence of potentially harmful algae was observed throughout the study period, including toxigenic dinoflagellates such as Alexandrium catenella (Group I of the A. tamarense complex), A. ostenfeldii, Dinophysis acuminata, Gonyaulax spinifera, Azadinium sp., and the diatoms Pseudo-nitzschia australis and P. fraudulenta. Toxic dinoflagellates were detected in low densities whereas a Pseudo-nitzschia bloom was observed in late February. Isolates of A. catenella and P. delicatissima sensu stricto were phylogenetically characterized. The toxin profile of A. catenella was dominated by GTX4, while P. delicatissima sensu stricto showed no production of the neurotoxin domoic acid in culture conditions. The results provide base-line information for the management of harmful algal blooms in this little explored subantarctic area.


Assuntos
Aquicultura , Diatomáceas/química , Dinoflagelados/química , Toxinas Marinhas/análise , Fitoplâncton/química , Animais , Biomassa , Diatomáceas/classificação , Diatomáceas/crescimento & desenvolvimento , Dinoflagelados/classificação , Dinoflagelados/crescimento & desenvolvimento , Proliferação Nociva de Algas , Microalgas/química , Microalgas/classificação , Microalgas/crescimento & desenvolvimento , Fitoplâncton/classificação , Fitoplâncton/crescimento & desenvolvimento , América do Sul
3.
Fa Yi Xue Za Zhi ; 35(4): 444-447, 2019 Aug.
Artigo em Inglês, Chinês | MEDLINE | ID: mdl-31532155

RESUMO

Abstract: Objective To detect the diatom population diversity in Dianchi by constructing a 18S rDNA clone library. Methods DNA from diatoms in 6 water samples of Dianchi was amplified with diatom 18S rDNA specific primer.The 18S rDNA clone library was constructed, and clones were randomly selected for sequence. Sequence alignment was performed by BLAST. The diatom population distribution in Dianchi was analyzed and the phylogenetic tree of diatom 18S rDNA in Dianchi waters was established with the MEGA v7.0.14 software. Results Two hundred and forty clones were sequenced, with 167 diatom sequences obtained, including 11 diatom species such as Stephanodiscus, Diatoma, and Melosira. There were certain differences in diatom population distribution among the 6 samples. Conclusion The population distribution of diatom species in Dianchi shows unique features and the sequence analysis of diatom 18S rDNA has a certain reference value to the inference of forensic drowning sites.


Assuntos
Diatomáceas/classificação , Filogenia , RNA Ribossômico 18S/genética , China , DNA Ribossômico/genética , Afogamento , Ciências Forenses , Humanos
4.
Environ Monit Assess ; 191(10): 603, 2019 Sep 03.
Artigo em Inglês | MEDLINE | ID: mdl-31482206

RESUMO

The spatial and temporal variation of phytoplankton communities including HAB species in relation to the environmental characteristics was investigated in the protected meso-oligotrophic Mellah lagoon located in the South Western Mediterranean. During 2016, a biweekly monitoring of phytoplankton assemblages and the main abiotic factors were realized at three representative stations. Taxonomic composition, abundance, and diversity index were determined. In total, 227 phytoplankton species (160 diatoms and 53 dinoflagellates) were inventoried. There was a clear dominance of diatoms (62.9%) compared with dinoflagellates (36.8%). Diatoms dominated in spring and dinoflagellates developed in summer and early autumn in Mellah showing a marked seasonal trend. Data showed that the dynamic of the phytoplankton taxa evolving in the lagoon was mainly driven by temperature and salinity. For the first time, a number of potentially toxic species have been identified, including 2 diatoms (Pseudo-nitzschia group delicatissima, Pseudo-nitzschia group seriata) and 5 dinoflagellates (Alexandrium minutum, Alexandrium tamarense/catenella, Dinophysis acuminata, Dinophysis sacculus, Prorocentrum lima). These harmful species could threat the functioning of the Mellah lagoon and human health and require the establishment of a monitoring network. Finally, our study suggests that the observed decrease of the phytoplankton diversity between 2001 and 2016 could result from the reduction in water exchanges between the lagoon and the adjacent coast following the gradual clogging of the channel.


Assuntos
Meio Ambiente , Monitoramento Ambiental , Fitoplâncton/classificação , Estações do Ano , Argélia , Diatomáceas/classificação , Diatomáceas/fisiologia , Dinoflagelados/classificação , Dinoflagelados/fisiologia , Fitoplâncton/fisiologia , Salinidade , Temperatura Ambiente
5.
Sci Justice ; 59(3): 292-305, 2019 05.
Artigo em Inglês | MEDLINE | ID: mdl-31054818

RESUMO

Environmental indicators are increasingly sought and analysed in a range of forensic reconstructions. Although the majority of casework and research studies are concerned with the criminal investigation of terrestrial habitats (soils, sediments, plants etc.), freshwater environments are also frequently encountered as crime scenes. As such, microalgae, particularly diatoms, may provide useful circumstantial trace evidence following their transfer to a victim or perpetrator. Diatom analysis is a relatively underused technique in forensic ecology, although an increased empirical research focus is beginning to recognise the evidential value of a transferred assemblage. This study aimed to examine three of the spatial and temporal variables known to influence the extent of an initial transfer of trace particulates, within the context of freshwater diatoms to clothing. A series of experiments were designed to consider the impact of recipient surface characteristics (clothing type), source environment conditions (seasonality), and morphological (type of diatom) variability, on the total number (no. per cm2) and species richness (total no. sp.) of an evidential diatom sample recovered from clothing. Nine commonly used clothing materials were immersed in a freshwater river at three times of year - the early and late spring and in the winter. Diatoms were recovered using a H2O2 extraction technique and examined microscopically. The results demonstrated that diatom transfer to clothing varies significantly, with a greater abundance and a higher species richness transferred to coarse woven surfaces including acrylic, linen, and viscose. Significantly fewer diatoms were transferred to clothing in the winter, in line with seasonal fluctuations in the source environment diatom community. Furthermore, variation in the relative abundance of particular diatom species was identified between clothing types, provisionally suggesting that morphological characteristics may also support or limit the transfer of material. These findings highlight that, although clothing may offer a valuable repository of freshwater diatom trace evidence, the interpretation of evidential material should be approached within an exclusionary framework. Thus, empirical data has been generated to develop evidence bases within forensic ecology, demonstrating some of the spatial and temporal factors which may contribute to or limit the transfer of evidence.


Assuntos
Vestuário , Diatomáceas/classificação , Diatomáceas/isolamento & purificação , Análise Espaço-Temporal , Ciências Forenses/métodos , Água Doce/análise , Microscopia/métodos , Estações do Ano
6.
An Acad Bras Cienc ; 91(2): e20170863, 2019 May 23.
Artigo em Inglês | MEDLINE | ID: mdl-31141008

RESUMO

Diatom growth strategies, which are used as a proxy to analyze disturbances and environmental impacts, can also provide reliable information about environmental gradients. In this study, we used diatom communities and biological traits to assess the structure of epilithic diatoms after an oil spill in a large tributary of the Iguaçu River (Paraná, Brazil). Epilithon and water samples were taken on July 12th, 2004, and after an unexpected oil spill, on the following days: 09/19, 10/03, and 10/13/2004. We observed that the spill caused a distinct shift in both diatom composition and guild group. Diversity decreased and pollution-tolerant diatoms of the motile group became dominant in response to the elevated nutrient levels and reduced light. Tube-forming diatoms, which are strong competitors for light, dominated the epilithon 24 days after the oil spill. Both diatom guilds and growth forms were successfully used to predict the environmental conditions. While diatom guilds responded to disturbances along a temporal gradient, changes inside the guilds were the main factor for understanding the environmental gradient.


Assuntos
Diatomáceas/efeitos dos fármacos , Monitoramento Ambiental/métodos , Petróleo/efeitos adversos , Óleos Vegetais/efeitos adversos , Poluentes Químicos da Água/efeitos adversos , Brasil , Vazamento de Resíduos Químicos , Diatomáceas/classificação , Diatomáceas/crescimento & desenvolvimento , Rios/química
7.
Environ Sci Pollut Res Int ; 26(17): 17512-17519, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-31025277

RESUMO

Phytoplankton assemblages were investigated in 2015 along the seasonal changes of the Genhe River in the Greater Hinggan Mountains. The survey was performed in June (spring), August (summer), and October (autumn) at nine sampling stations to study the community composition, abundance, and biodiversity. The results showed that 61 species belonging to 16 genera were identified, including Bacillariophyta of 31 species, Dinophyta 2 species, Cyanophyta 2 species, Chlorophyta 20 species, Chrysophyta 2 species, and Cryptophyta 1 species; Besides, Bacillariophyta are dominant species. Shannon-Wiener (H') and Pielou (J') indices indicated that phytoplankton community was stable. And these two indices were significantly lower in summer than in spring and autumn. Phytoplankton abundance and biomass show significant differences in each season. The total phytoplankton abundance (1122.3 × 104 ind/L) and biomass (6.5709 mg/L) in summer are much higher than that in spring and autumn. There were few species and low abundance and biomass in the upper reaches of Genhe River; this fact can be explained by the cold climate in the Greater Higgnan Mountains region. Canonical correspondence analysis (CCA) was used to analyze the data. It revealed that Fe3+, Cu2+, pH, and water temperature (WT) were responsible for most of the variation in space in the phytoplankton community. These environmental parameters play an essential role in the community structure variation of phytoplankton in the upper reaches of Genhe River, the strong association between phytoplankton community structure and ecological factors is varied in each season.


Assuntos
Clorófitas/química , Cianobactérias/química , Diatomáceas/classificação , Dinoflagelados/química , Fitoplâncton/classificação , Rios/química , Biodiversidade , Biomassa , China , Diatomáceas/química , Ecologia , Fitoplâncton/química , Estações do Ano , Temperatura Ambiente , Qualidade da Água
8.
Protist ; 170(2): 121-140, 2019 04.
Artigo em Inglês | MEDLINE | ID: mdl-30954839

RESUMO

With the increasing application of molecular techniques for diatom species discovery and identification, it is important both from a taxonomic as well as an ecological and applied perspective, to understand in which groups morphological species delimitation is congruent with molecular approaches, or needs reconsideration. Moreover, such studies can improve our understanding of morphological trait evolution in this important group of microalgae. In this study, we used morphometric analysis on light microscopy (LM) micrographs in SHERPA, detailed scanning electron microscopy (SEM), and cytological observations in LM to examine 70 clones belonging to eight distinct molecular lineages of the cosmopolitan terrestrial diatom Pinnularia borealis. Due to high within-lineage variation, no conclusive morphological separation in LM nor SEM could be detected. Morphological stasis due to the "low-morphology" problem or stabilizing selection, as well as parallel/convergent evolution, phenotypic plasticity and structural inheritance are discussed as potential drivers for the observations. Altogether, P. borealis is truly cryptic, in contrast to the majority of other diatom species complexes which turned out to be pseudo-cryptic following detailed morphological analysis.


Assuntos
Biodiversidade , Diatomáceas/classificação , Diatomáceas/ultraestrutura , Microscopia , Microscopia Eletrônica de Varredura
9.
ISME J ; 13(8): 1960-1974, 2019 08.
Artigo em Inglês | MEDLINE | ID: mdl-30911131

RESUMO

Ammonium is a central nutrient in aquatic systems. Yet, cell-specific ammonium assimilation among diverse functional plankton is poorly documented in field communities. Combining stable-isotope incubations (15N-ammonium, 15N2 and 13C-bicarbonate) with secondary-ion mass spectrometry, we quantified bulk ammonium dynamics, N2-fixation and carbon (C) fixation, as well as single-cell ammonium assimilation and C-fixation within plankton communities in nitrogen (N)-depleted surface waters during summer in the Baltic Sea. Ammonium production resulted from regenerated (≥91%) and new production (N2-fixation, ≤9%), supporting primary production by 78-97 and 2-16%, respectively. Ammonium was produced and consumed at balanced rates, and rapidly recycled within 1 h, as shown previously, facilitating an efficient ammonium transfer within plankton communities. N2-fixing cyanobacteria poorly assimilated ammonium, whereas heterotrophic bacteria and picocyanobacteria accounted for its highest consumption (~20 and ~20-40%, respectively). Surprisingly, ammonium assimilation and C-fixation were similarly fast for picocyanobacteria (non-N2-fixing Synechococcus) and large diatoms (Chaetoceros). Yet, the population biomass was high for Synechococcus but low for Chaetoceros. Hence, autotrophic picocyanobacteria and heterotrophic bacteria, with their high single-cell assimilation rates and dominating population biomass, competed for the same nutrient source and drove rapid ammonium dynamics in N-depleted marine waters.


Assuntos
Compostos de Amônio/metabolismo , Cianobactérias/metabolismo , Plâncton/metabolismo , Compostos de Amônio/análise , Países Bálticos , Carbono/análise , Ciclo do Carbono , Cianobactérias/classificação , Diatomáceas/classificação , Diatomáceas/metabolismo , Processos Heterotróficos , Fixação de Nitrogênio , Plâncton/classificação , Estações do Ano , Água do Mar/microbiologia
10.
Extremophiles ; 23(3): 347-357, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-30888506

RESUMO

Alkaline soda lakes are unique habitats found in specific geographic regions, usually with dry climate. The Carpathian Basin is one of those regions very important for habitat and biodiversity conservation in Europe, with natural soda lakes found in Austria, Hungary and Serbia. In comparison to other two countries from Central Europe, algal biodiversity studies of saline soda lakes in Serbia are scarce. Lake Velika Rusanda has the highest measured salinity of all saline lakes in the Carpathian Basin and there were no reports of its diatom species richness and diversity till now. We conducted 2-year investigation programme to study biodiversity and seasonal dynamics of diatoms in this lake. A total of 27 diatom taxa were found, almost all of them attached to reed and much less in benthos and plankton. Five new diatom species for Serbia were recorded, Craticula halopannonica, Navicymbula pusilla, Hantzschia weyprechtii, Nitzschia thermaloides and Navicula staffordiae. The last mentioned is new for Europe as well. Lake Velika Rusanda is inhabited mostly by alkaliphilous and halophilic diatoms. Since diatoms are used as bioindicators in soda lakes, our results will improve their further application in ecological status assessment of these fragile habitats in the Carpathian Basin.


Assuntos
Biodiversidade , Diatomáceas , Lagos/microbiologia , Salinidade , Microbiologia da Água , Diatomáceas/classificação , Diatomáceas/crescimento & desenvolvimento , Sérvia
11.
Environ Monit Assess ; 191(4): 201, 2019 Mar 02.
Artigo em Inglês | MEDLINE | ID: mdl-30826892

RESUMO

Both environmental and geographic factors interact to structure the metacommunities in river networks, but the importance of these factors is difficult to distinguish. We used six aquatic taxonomic groups to test the relationship between environmental and geographic factors and their effect on species turnover patterns in an agriculturally dominated river (Chaohu Lake Basin, China). The relationships between three dissimilarity indices and geographic distance were assessed using the Mantel test while considering the differences in environmental factors between sites. Then, we employed a variation partitioning method to distinguish the isolated and combined effects of environmental and geographic distance on species turnover. There were significant relationships between environmental distance and species turnover in all groups. All organisms except periphytic diatoms were significantly correlated with two geographic (Euclidean and network) distances when the Chao dissimilarity index was considered. The results suggest that the strength of the correlations changed with environmental and geographic distances and with the aquatic community. The communities displayed more complex relationships with the distance measures when different dissimilarity (Jaccard, Chao, and Bray-Curtis dissimilarity) indices were considered. Nevertheless, aquatic communities are strongly influenced by both environmental and geographic distance, and the former has a stronger effect than the latter.


Assuntos
Biodiversidade , Diatomáceas/classificação , Monitoramento Ambiental , Peixes/classificação , Fitoplâncton/classificação , Rotíferos/classificação , Zooplâncton/classificação , Agricultura , Animais , China , Diatomáceas/isolamento & purificação , Geografia , Lagos , Fitoplâncton/isolamento & purificação , Rios , Rotíferos/isolamento & purificação , Zooplâncton/isolamento & purificação
12.
Environ Sci Pollut Res Int ; 26(14): 14266-14276, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-30864033

RESUMO

Ecosystem-based management is one of the strategies to protect the coastal areas. One of the key elements is phytoplankton community composition since it represents a good indicator of anthropogenic pressures. This identifies the seasonal patterns of phytoplankton, and its alterations by the stress factors induced by human activities are highly valuable. This research represents the first attempt to study that 476 km of western Mediterranean coastal belongs to the Valencian Community (Spain) based on the phytoplankton composition approach. The water samples during a 5-year period (6757 water samples) were taken to determine its phytoplankton group's dynamics and its relationship with anthropogenic stressors by means of a series of plots and statistical analyses. Diatoms are the group that most contribute to the whole community composition with two periods of maximum abundance. The Prasinophyceae and Cryptophyceae show unimodal patterns varying its maximum values depending on the season. The picocyanobacteria group exhibited the clearest and best-defined pattern. Other groups have no clear seasonal pattern and become abundant in areas of higher anthropogenic pressure. Graphical abstract Figure A contains poor quality of text in image. Otherwise, please provide replacement figure file.A new graphical abstract, with higher quality is attached.


Assuntos
Monitoramento Ambiental/métodos , Fitoplâncton/crescimento & desenvolvimento , Estações do Ano , Poluentes Químicos da Água/análise , Diatomáceas/classificação , Diatomáceas/efeitos dos fármacos , Diatomáceas/crescimento & desenvolvimento , Ecossistema , Humanos , Estudos Longitudinais , Mar Mediterrâneo , Fitoplâncton/classificação , Fitoplâncton/efeitos dos fármacos , Água do Mar/química , Espanha
13.
Environ Geochem Health ; 41(5): 1909-1921, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-30701355

RESUMO

Aljustrel mining area (South Portugal) is a part of the Iberian Pyrite Belt and encloses six sulfide mineral masses. This mine is classified of high environmental risk due to the large tailings' volume and acid mine drainage (AMD)-affected waters generated by sulfides' oxidation. The use of biological indicators (e.g., diatoms) revealed to be an important tool to address the degree of AMD contamination in waters. Multivariate analysis has been used as a relevant approach for the characterization of AMD processes. Cluster analysis was used to integrate the significant amount and diversity of variables (physicochemical and biological), discriminating the different types of waters, characterized by the high complexity occurring in this region. The distinction of two main marked phenomena was achieved: (1) the circumneutral-Na-Cl water type (sites DA, PF, BX, BF, RO, CB), expressing the geological contributions of the Cenozoic sediments of Sado river basin, with high diatom diversity (predominating brackish diatoms as Entomoneis alata); and (2) the acid-metal-sulfated water type (sites BM, JU, RJ, AA, MR, BE, PC, AF), reflecting both the AMD contamination and the dissolution of minerals (e.g., silicates) from the hosting rocks, potentiated by the extremely low pH. This last group of sites showed lower diatom diversity but with typical diatoms from acid- and metal-contaminated waters (e.g., Pinnularia aljustrelica). In addition to these two water types, this hierarchical classification method also allowed to distinguish individual cases in subclusters, for example, treated dams (DC, DD), with alkaline substances (lime/limestone), that changed the physicochemical dynamics of the contaminated waters.


Assuntos
Diatomáceas/fisiologia , Monitoramento Ambiental , Mineração , Rios/química , Poluentes Químicos da Água/análise , Ácidos/análise , Diatomáceas/classificação , Diatomáceas/crescimento & desenvolvimento , Ferro/análise , Metais/análise , Minerais/análise , Portugal , Sulfetos/análise
14.
J Basic Microbiol ; 59(5): 504-510, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-30811614

RESUMO

We examined the dynamic of periphytic diatom colonization and litter decompositional pattern in an intermittent stream of South India. Litter bags containing 5 g of fresh fallen leaves (belongs to five different species of angiosperms) were fixed in the five stream pools and they were collected after 7, 14, 21, and 28 days of incubation. This experiment showed the diversity, richness, and abundance of diatoms developed on leaf litter. In total, 131 µl-1 cells of diatoms under four species in three families were collected from decomposing leaves in benthic area of stream pools. During experiment, 142 µl-1 cells representing 11 taxa in 10 families were observed in litter bags. The colonization of epiphytic diatom was rapid in early stage of litter decomposition. The higher number of colonization made by Asterionella and Stenopterobia found in litter bags of all experimental weeks. These findings suggest that the rapid microbial colonization (ephiphytic algae) was occurred in the early stage of litter decomposition in an intermittent tropical stream and a comprehensive ecological investigation in perennial natural streams in India is needed.


Assuntos
Diatomáceas/crescimento & desenvolvimento , Folhas de Planta/metabolismo , Rios , Biodegradação Ambiental , Biodiversidade , Diatomáceas/classificação , Diatomáceas/genética , Índia , Magnoliopsida/metabolismo , Fatores de Tempo
15.
FEMS Microbiol Lett ; 366(2)2019 01 01.
Artigo em Inglês | MEDLINE | ID: mdl-30629176

RESUMO

Diatom diazotroph associations (DDAs) are a widespread marine planktonic symbiosis between several diatom genera and di-nitrogen (N2)-fixing bacteria. Combining single cell confocal microscopy observations and molecular genetic approaches on individual field collected cells, we determined the phylogenetic diversity, distribution and evolution of the DDAs. Confocal analyses coupled with 3-D imaging re-evaluated the cellular location of DDA symbionts. DDA diversity was resolved by paired gene sequencing (18S rRNA and rbcL genes, 16S rRNA and nifH genes). A survey using the newly acquired sequences against public databases found sequences with high similarity (99-100%) to either host (18S rRNA) or symbiont (16S rRNA) in atypical regions for DDAs (high latitudes, anoxic basin and copepod gut). Concatenated phylogenies were congruent for the host and cyanobacteria sequences and implied co-evolution. Time-calibrated trees dated the appearance of N2 fixing planktonic symbiosis from 100-50Mya and were consistent with the symbiont cellular location: symbioses with internal partners are more ancient. An ancestral state reconstruction traced the evolution of traits in DDAs and highlight that the adaptive radiation to the marine environment was likely facilitated by the symbiosis. Our results present the evolutionary nature of DDAs and provide new genetic and phenotypic information for these biogeochemically relevant populations.


Assuntos
Evolução Biológica , Cianobactérias/genética , Diatomáceas/genética , Variação Genética , Simbiose , Cianobactérias/classificação , Cianobactérias/isolamento & purificação , Cianobactérias/fisiologia , Diatomáceas/classificação , Diatomáceas/microbiologia , Diatomáceas/fisiologia , Fixação de Nitrogênio , Filogenia , Água do Mar/microbiologia , Água do Mar/parasitologia
16.
Braz J Biol ; 79(3): 521-526, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30517276

RESUMO

Since the foundation of the Malacological Center in 1980, Universidad Centro Americana (UCA), Managua-Nicaragua, has been monitoring and collecting the marine, terrestrial, fluvial and lake mollusk population of the country. Many specimens have been photographed by Scanning Electronic Microscope (SEM), and in one of these, observation of the hairy periostracum reveals a seemingly thriving population of minute protists in possible symbiosis with their host. Adequate magnification and comparison with previous studies allowed the determination of these hosts as diatoms, testaceous amoebae, yeast, phacus, spores and other undetermined organisms which occur in tropical forests on rocks, trees and leaves. Here illustrated are diatoms and other organisms detected for the first time on the periostracum of a tropical rainforest mollusk.


Assuntos
Diatomáceas/fisiologia , Caramujos/fisiologia , Simbiose , Animais , Diatomáceas/classificação , Microscopia Eletrônica de Varredura , Nicarágua , Floresta Úmida
18.
Microb Ecol ; 77(2): 288-303, 2019 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-30019110

RESUMO

Two annual Baltic Sea phytoplankton blooms occur in spring and summer. The bloom intensity is determined by nutrient concentrations in the water, while the period depends on weather conditions. During the course of the bloom, dead cells sink to the sediment where their degradation consumes oxygen to create hypoxic zones (< 2 mg/L dissolved oxygen). These zones prevent the establishment of benthic communities and may result in fish mortality. The aim of the study was to determine how the spring and autumn sediment chemistry and microbial community composition changed due to degradation of diatom or cyanobacterial biomass, respectively. Results from incubation of sediment cores showed some typical anaerobic microbial processes after biomass addition such as a decrease in NO2- + NO3- in the sediment surface (0-1 cm) and iron in the underlying layer (1-2 cm). In addition, an increase in NO2- + NO3- was observed in the overlying benthic water in all amended and control incubations. The combination of NO2- + NO3- diffusion plus nitrification could not account for this increase. Based on 16S rRNA gene sequences, the addition of cyanobacterial biomass during autumn caused a large increase in ferrous iron-oxidizing archaea while diatom biomass amendment during spring caused minor changes in the microbial community. Considering that OTUs sharing lineages with acidophilic microorganisms had a high relative abundance during autumn, it was suggested that specific niches developed in sediment microenvironments. These findings highlight the importance of nitrogen cycling and early microbial community changes in the sediment due to sinking phytoplankton before potential hypoxia occurs.


Assuntos
Bactérias/isolamento & purificação , Cianobactérias/crescimento & desenvolvimento , Diatomáceas/crescimento & desenvolvimento , Sedimentos Geológicos/microbiologia , Fitoplâncton/crescimento & desenvolvimento , Bactérias/classificação , Bactérias/genética , Biomassa , Cianobactérias/classificação , Cianobactérias/genética , Cianobactérias/isolamento & purificação , Diatomáceas/classificação , Diatomáceas/genética , Diatomáceas/isolamento & purificação , Eutrofização , Sedimentos Geológicos/química , Nitratos/análise , Nitratos/metabolismo , Nitritos/análise , Nitritos/metabolismo , Filogenia , Fitoplâncton/classificação , Fitoplâncton/genética , Fitoplâncton/isolamento & purificação , Estações do Ano , Água do Mar/química , Água do Mar/microbiologia
19.
Artigo em Inglês | MEDLINE | ID: mdl-29527965

RESUMO

Diatoms are the most diverse lineage of algae and at the base of most aquatic food webs, but only 11 of their mitochondrial genomes have been described. Herein, we present the mitochondrial genomes of six diatom species, including: Melosira undulata, Nitzschia alba, Surirella sp., Entomoneis sp., Halamphora coffeaeformis, and Halamphora calidilacuna. Comparison of these six genomes to the 11 currently published diatom mitochondrial genomes revealed a novel ubiquitous feature block consisting of tatC-orf157-rps11. The presence of intronic retrotransposable elements in the barcoding region of cox1 in the Halamphora genomes may explain historic difficulty (especially PCR) with cox1 as a universal barcode for diatoms. Our analysis suggests that high rates of variability in number and position of introns, in many commonly used coding sequences, prevent these from being universally viable as barcodes for diatoms. Therefore, we suggest researchers examine the chloroplast and/or nuclear genomes for universal barcoding markers.


Assuntos
Diatomáceas/genética , Complexo IV da Cadeia de Transporte de Elétrons/genética , Genoma Mitocondrial , Íntrons , Polimorfismo Genético , Diatomáceas/classificação , Evolução Molecular , Filogenia , Retroelementos , Alinhamento de Sequência
20.
Proc Natl Acad Sci U S A ; 115(52): E12275-E12284, 2018 12 26.
Artigo em Inglês | MEDLINE | ID: mdl-30538208

RESUMO

Diatoms are prominent eukaryotic phytoplankton despite being limited by the micronutrient iron in vast expanses of the ocean. As iron inputs are often sporadic, diatoms have evolved mechanisms such as the ability to store iron that enable them to bloom when iron is resupplied and then persist when low iron levels are reinstated. Two iron storage mechanisms have been previously described: the protein ferritin and vacuolar storage. To investigate the ecological role of these mechanisms among diatoms, iron addition and removal incubations were conducted using natural phytoplankton communities from varying iron environments. We show that among the predominant diatoms, Pseudo-nitzschia were favored by iron removal and displayed unique ferritin expression consistent with a long-term storage function. Meanwhile, Chaetoceros and Thalassiosira gene expression aligned with vacuolar storage mechanisms. Pseudo-nitzschia also showed exceptionally high iron storage under steady-state high and low iron conditions, as well as following iron resupply to iron-limited cells. We propose that bloom-forming diatoms use different iron storage mechanisms and that ferritin utilization may provide an advantage in areas of prolonged iron limitation with pulsed iron inputs. As iron distributions and availability change, this speculated ferritin-linked advantage may result in shifts in diatom community composition that can alter marine ecosystems and biogeochemical cycles.


Assuntos
Diatomáceas/metabolismo , Ferro/metabolismo , Diatomáceas/classificação , Diatomáceas/crescimento & desenvolvimento , Ecossistema , Ferritinas/metabolismo , Fitoplâncton/crescimento & desenvolvimento , Fitoplâncton/metabolismo
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