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1.
Am J Bot ; 111(2): e16275, 2024 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-38303667

RESUMO

PREMISE: Snow is an important environmental factor affecting plant distribution. Past changes in snowfall regimes may have controlled the demographies of snow-dependent plants. However, our knowledge of changes in the distribution and demographies of such plants is limited because of the lack of fossil records. METHODS: Population genetic and landscape genetic analyses were used to investigate the response of population dynamics of Arnica mallotopus (Asteraceae)-a plant confined to heavy-snow areas of Japan-to changes in snowfall regimes from the Last Glacial Period to the Holocene. RESULTS: The population genetic analysis suggested that the four geographic lineages diverged during the Last Glacial Period. The interaction between reduced snowfall and lower temperatures during this period likely triggered population isolation in separate refugia. Subpopulation differentiation in the northern group was lower than in the southern group. Our ecological niche model predicted that the current distribution was patchy in the southern region; that is, the populations were isolated by topologically flat and climatically unsuitable lowlands. The landscape genetic analysis suggested that areas with little snowfall acted as barriers to the Holocene expansion of species distribution and continued limiting gene flow between local populations. CONCLUSIONS: These findings indicate that postglacial population responses vary among regions and are controlled by environmental and geographic factors. Thus, changes in snowfall regime played a major role in shaping the distribution and genetic structure of the snow-dependent plant.


Assuntos
Arnica , Variação Genética , Japão , Neve , Dinâmica Populacional
2.
Nature ; 625(7994): 293-300, 2024 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-38200299

RESUMO

Documenting the rate, magnitude and causes of snow loss is essential to benchmark the pace of climate change and to manage the differential water security risks of snowpack declines1-4. So far, however, observational uncertainties in snow mass5,6 have made the detection and attribution of human-forced snow losses elusive, undermining societal preparedness. Here we show that human-caused warming has caused declines in Northern Hemisphere-scale March snowpack over the 1981-2020 period. Using an ensemble of snowpack reconstructions, we identify robust snow trends in 82 out of 169 major Northern Hemisphere river basins, 31 of which we can confidently attribute to human influence. Most crucially, we show a generalizable and highly nonlinear temperature sensitivity of snowpack, in which snow becomes marginally more sensitive to one degree Celsius of warming as climatological winter temperatures exceed minus eight degrees Celsius. Such nonlinearity explains the lack of widespread snow loss so far and augurs much sharper declines and water security risks in the most populous basins. Together, our results emphasize that human-forced snow losses and their water consequences are attributable-even absent their clear detection in individual snow products-and will accelerate and homogenize with near-term warming, posing risks to water resources in the absence of substantial climate mitigation.


Assuntos
Atividades Humanas , Neve , Meteorologia , Aquecimento Global/prevenção & controle , Aquecimento Global/estatística & dados numéricos , Temperatura , Abastecimento de Água/estatística & dados numéricos
5.
Sci Total Environ ; 915: 170148, 2024 Mar 10.
Artigo em Inglês | MEDLINE | ID: mdl-38246373

RESUMO

Antarctic snow is a thriving habitat for a diverse array of complex microorganisms, and can present in different colors due to algae blooms. However, the potential role of Antarctic snow as reservoirs for antibiotic resistance genes (ARGs) has not been studied. Using metagenomic sequencing, we studied ARGs in green-snow and red-snow on the Fildes Peninsula, Antarctica. Alpha and beta diversities of ARGs, as well as co-occurrence between ARGs and bacteria were assessed. The results showed that a total of 525 ARGs conferring resistance to 30 antibiotic classes were detected across the samples, with half of the ARGs presented in all samples. Green-snow exhibited a higher number of ARGs compared to red-snow. The most abundant ARGs conferring resistance to commonly used antibiotics, including disinfecting agents and antiseptics, peptide, isoniazid, MLS, fluoroquinolone, aminocoumarin, etc. Multidrug resistance genes stood out as the most diverse and abundant, with antibiotic efflux emerging as the dominant resistance mechanism. Interestingly, the composition of ARGs in green-snow markedly differed from that in red-snow, highlighting distinct ARG profiles. Beta-diversity partitioning showed a higher contribution of nestedness for ARG's variation in green-snow, while higher contribution of turnover in red-snow. Furthermore, the co-occurrence analysis between ARGs and bacteria unveiled intricate relationships, indicating that certain ARGs may have multiple potential hosts. The observed differences in co-occurrence networks between green-snow and red-snow suggested distinct host relationships between ARGs and bacteria in these colored snows. Given the increasing appearance of the colored snow around the world due to the climate change, the results shed light on the mystery and potential implication of ARGs in green and red Antarctic snow.


Assuntos
Antibacterianos , Neve , Antibacterianos/farmacologia , Regiões Antárticas , Genes Bacterianos , Bactérias/genética , Resistência Microbiana a Medicamentos/genética
6.
Glob Chang Biol ; 30(1): e17087, 2024 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-38273494

RESUMO

Increasing temperatures and winter precipitation can influence the carbon (C) exchange rates in arctic ecosystems. Feedbacks can be both positive and negative, but the net effects are unclear and expected to vary strongly across the Arctic. There is a lack of understanding of the combined effects of increased summer warming and winter precipitation on the C balance in these ecosystems. Here we assess the short-term (1-3 years) and long-term (5-8 years) effects of increased snow depth (snow fences) (on average + 70 cm) and warming (open top chambers; 1-3°C increase) and the combination in a factorial design on all key components of the daytime carbon dioxide (CO2 ) fluxes in a wide-spread heath tundra ecosystem in West Greenland. The warming treatment increased ecosystem respiration (ER) on a short- and long-term basis, while gross ecosystem photosynthesis (GEP) was only increased in the long term. Despite the difference in the timing of responses of ER and GEP to the warming treatment, the net ecosystem exchange (NEE) of CO2 was unaffected in the short term and in the long term. Although the structural equation model (SEM) indicates a direct relationship between seasonal accumulated snow depth and ER and GEP, there were no significant effects of the snow addition treatment on ER or GEP measured over the summer period. The combination of warming and snow addition turned the plots into net daytime CO2 sources during the growing season. Interestingly, despite no significant changes in air temperature during the snow-free time during the experiment, control plots as well as warming plots revealed significantly higher ER and GEP in the long term compared to the short term. This was in line with the satellite-derived time-integrated normalized difference vegetation index of the study area, suggesting that more factors than air temperature are drivers for changes in arctic tundra ecosystems.


Assuntos
Dióxido de Carbono , Ecossistema , Estações do Ano , Dióxido de Carbono/química , Temperatura , Neve , Tundra , Regiões Árticas , Solo/química
7.
Glob Chang Biol ; 30(1): e17085, 2024 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-38273566
8.
Glob Chang Biol ; 30(1): e17118, 2024 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-38273573

RESUMO

Climate change has had a significant impact on the seasonal transition dates of Arctic tundra ecosystems, causing diverse variations between distinct land surface classes. However, the combined effect of multiple controls as well as their individual effects on these dates remains unclear at various scales and across diverse land surface classes. Here we quantified spatiotemporal variations of three seasonal transition dates (start of spring, maximum normalized difference vegetation index (NDVImax ) day, end of fall) for five dominating land surface classes in the ice-free Greenland. Using a distributed snow model, structural equation modeling, and a random forest model, based on ground observations and remote sensing data, we assessed the indirect and direct effects of climate, snow, and terrain on seasonal transition dates. We then presented new projections of likely changes in seasonal transition dates under six future climate scenarios. The coupled climate, snow cover, and terrain conditions explained up to 61% of seasonal transition dates across different land surface classes. Snow ending day played a crucial role in the start of spring and timing of NDVImax . A warmer June and a decline in wind could advance the NDVImax day. Increased precipitation and temperature during July-August are the most important for delaying the end of fall. We projected that a 1-4.5°C increase in temperature and a 5%-20% increase in precipitation would lengthen the spring-to-fall period for all five land surface classes by 2050, thus the current order of spring-to-fall lengths for the five land surface classes could undergo notable changes. Tall shrubs and fens would have a longer spring-to-fall period under the warmest and wettest scenario, suggesting a competitive advantage for these vegetation communities. This study's results illustrate controls on seasonal transition dates and portend potential changes in vegetation composition in the Arctic under climate change.


Assuntos
Ecossistema , Tundra , Groenlândia , Estações do Ano , Regiões Árticas , Neve , Mudança Climática
9.
Glob Chang Biol ; 30(1): e17078, 2024 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-38273582

RESUMO

Microclimate-proximal climatic variation at scales of metres and minutes-can exacerbate or mitigate the impacts of climate change on biodiversity. However, most microclimate studies are temperature centric, and do not consider meteorological factors such as sunshine, hail and snow. Meanwhile, remote cameras have become a primary tool to monitor wild plants and animals, even at micro-scales, and deep learning tools rapidly convert images into ecological data. However, deep learning applications for wildlife imagery have focused exclusively on living subjects. Here, we identify an overlooked opportunity to extract latent, ecologically relevant meteorological information. We produce an annotated image dataset of micrometeorological conditions across 49 wildlife cameras in South Africa's Maloti-Drakensberg and the Swiss Alps. We train ensemble deep learning models to classify conditions as overcast, sunshine, hail or snow. We achieve 91.7% accuracy on test cameras not seen during training. Furthermore, we show how effective accuracy is raised to 96% by disregarding 14.1% of classifications where ensemble member models did not reach a consensus. For two-class weather classification (overcast vs. sunshine) in a novel location in Svalbard, Norway, we achieve 79.3% accuracy (93.9% consensus accuracy), outperforming a benchmark model from the computer vision literature (75.5% accuracy). Our model rapidly classifies sunshine, snow and hail in almost 2 million unlabelled images. Resulting micrometeorological data illustrated common seasonal patterns of summer hailstorms and autumn snowfalls across mountains in the northern and southern hemispheres. However, daily patterns of sunshine and shade diverged between sites, impacting daily temperature cycles. Crucially, we leverage micrometeorological data to demonstrate that (1) experimental warming using open-top chambers shortens early snow events in autumn, and (2) image-derived sunshine marginally outperforms sensor-derived temperature when predicting bumblebee foraging. These methods generate novel micrometeorological variables in synchrony with biological recordings, enabling new insights from an increasingly global network of wildlife cameras.


Assuntos
Animais Selvagens , Aprendizado Profundo , Animais , Humanos , Tempo (Meteorologia) , Neve , Biodiversidade
10.
Plant Cell Environ ; 47(3): 976-991, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-38164069

RESUMO

Mosses are vital components of ecosystems, exhibiting remarkable adaptability across diverse habitats from deserts to polar ice caps. Sanionia uncinata (Hedw.) Loeske, a dominant Antarctic moss survives extreme environmental condition through perennial lifecycles involving growth and dormancy alternation. This study explores genetic controls and molecular mechanisms enabling S. uncinata to cope with seasonality of the Antarctic environment. We analysed the seasonal transcriptome dynamics of S. uncinata collected monthly from February 2015 to January 2016 in King George Island, Antarctica. Findings indicate that genes involved in plant growth were predominantly upregulated in Antarctic summer, while those associated with protein synthesis and cell cycle showed marked expression during the winter-to-summer transition. Genes implicated in cellular stress and abscisic acid signalling were highly expressed in winter. Further, validation included a comparison of the Antarctic field transcriptome data with controlled environment simulation of Antarctic summer and winter temperatures, which revealed consistent gene expression patterns in both datasets. This proposes a seasonal gene regulatory model of S. uncinate to understand moss adaptation to extreme environments. Additionally, this data set is a valuable resource for predicting genetic responses to climatic fluctuations, enhancing our knowledge of Antarctic flora's resilience to global climate change.


Assuntos
Briófitas , Briófitas/genética , Ecossistema , Regiões Antárticas , Neve , Ambientes Extremos , Perfilação da Expressão Gênica
11.
Sci Total Environ ; 916: 169896, 2024 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-38185160

RESUMO

Widespread shrubification across the Arctic has been generally attributed to increasing air temperatures, but responses vary across species and sites. Wood structures related to the plant hydraulic architecture may respond to local environmental conditions and potentially impact shrub growth, but these relationships remain understudied. Using methods of dendroanatomy, we analysed shrub ring width (RW) and xylem anatomical traits of 80 individuals of Salix glauca L. and Betula nana L. at a snow manipulation experiment in Western Greenland. We assessed how their responses differed between treatments (increased versus ambient snow depth) and soil moisture regimes (wet and dry). Despite an increase in snow depth due to snow fences (28-39 %), neither RW nor anatomical traits in either species showed significant responses to this increase. In contrast, irrespective of the snow treatment, the xylem specific hydraulic conductivity (Ks) and earlywood vessel size (LA95) for the study period were larger in S. glauca (p < 0.1, p < 0.01) and B. nana (p < 0.01, p < 0.001) at the wet than the dry site, while both species had larger vessel groups at the dry than the wet site (p < 0.01). RW of B. nana was higher at the wet site (p < 0.01), but no differences were observed for S. glauca. Additionally, B. nana Ks and LA95 showed different trends over the study period, with decreases observed at the dry site (p < 0.001), while for other responses no difference was observed. Our results indicate that, taking into account ontogenetic and allometric trends, hydraulic related xylem traits of both species, along with B. nana growth, were influenced by soil moisture. These findings suggest that soil moisture regime, but not snow cover, may determine xylem responses to future climate change and thus add to the heterogeneity of Arctic shrub dynamics, though more long-term species- and site- specific studies are needed.


Assuntos
Neve , Solo , Humanos , Groenlândia , Regiões Árticas , Xilema/fisiologia
12.
Environ Sci Pollut Res Int ; 31(3): 3413-3424, 2024 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-38114701

RESUMO

Tibetan Plateau (TP) is known as the water tower of Asia, and glaciers are solid reservoirs that can regulate the amount of water. Black carbon (BC), as one of the important factors accelerating glacier melting, is causing evident environmental effects in snow and ice. However, a systematical summary of the potential sources, analytical methods, distributions, and environmental effects of BC in snow and ice on the TP's glaciers is scarce. Therefore, this study drew upon existing research on snow and ice BC on glaciers of the TP to describe the detection methods and uncertainties associated with them to clarify the concentrations of BC in snow and ice and their climatic effects. The primary detection methods are the optical method, the thermal-optical method, the thermochemical method, and the single-particle soot photometer method. However, few studies have systematically compared the results of BC and this study found that concentrations of BC in different types of snow and ice varied by 1-3 orders of magnitude, which drastically affected the regional hydrologic process by potentially accelerating the ablation of glaciers by approximately 15% and reducing the duration of snow accumulation by 3-4 days. In general, results obtained from the various testing methods differ drastically, which limited the systematical discussion. Accordingly, a universal standard for the sampling and measurement should be considered in the future work, which will be beneficial to facilitate the comparison of the spatiotemporal features and to provide scientific data for the model-simulated climatic effects of BC.


Assuntos
Neve , Fuligem , Tibet , Monitoramento Ambiental/métodos , Camada de Gelo , Água , Carbono/análise
13.
J Environ Manage ; 351: 119905, 2024 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-38159303

RESUMO

The classification of floods may be a supporting tool for decision-makers in regard to water management, including flood protection. The main objective of this work is the classification of flood generation mechanisms in 28 catchments of the upper Vistula basin. A significant innovation in this study lies in the utilization of decision trees for flood classification. The methodology has so far been applied in the Alpine region. The analysis reveals that peak daily precipitation in the catchments mainly occurs in summer, particularly from June to August. Maximal daily snowmelt typically happens at the end of winter (March to April) and occasionally in November. Winter peaks are observed in March to April and, in some areas, in November to December, while summer peaks occur in May and, in specific catchments, in October. Higher peak flows for annual floods are noted in March to April and June to August. Most annual floods in the Upper Vistula basin are classified as Rain-on-Snow Floods (RoSFs) or Lowland River Floods (LRFs). LRFs contribute from 19% to almost 72%, while RoSFs range from 18% to 75%. In Season 1 (summer), most seasonal floods are identified as LRFs (51%-100%), with very few as RoSFs (0%-46.9%). In Season 2 (winter), the opposite pattern is observed, with most RoSFs (48.4%-97.9%) and fewer LRFs (0%-20.6%). While there are changes in flood patterns, they are not statistically significant. Conducted studies and obtained results can be useful for the preparation of flood prevention documentation and for flood management in general.


Assuntos
Inundações , Chuva , Neve , Rios , Água
14.
J Contam Hydrol ; 260: 104286, 2024 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-38150790

RESUMO

Concentrations of total suspended solids (TSS), trace metals (Cu, Cd, Cr, Zn, Cd, Pb), Na and 16 US EPA priority PAHs in urban snow were studied in the City of Luleå in Northern Sweden. Snow was sampled at six central urban and suburban sites with various traffic intensities, in three sampling surveys (1994-95, 2002-03, 2020-21), repeated for three ages of the urban snow cover of 40, 80, and 120 days, respectively. The older data, from the 1994-95 and 2002-03 surveys, were obtained from the existing literature. The concentrations and mass loads of TSS and most trace metals studied (Zn, Cu, Pb, and Cd) varied with time. TSS, Zn, and Cu showed slightly higher concentrations and mass loads in the 2003 (TSS avg = 2300 µg/L, Zn avg = 620 µg/L and Cu avg = 250 µg/L) and 2021 (TSS avg = 1500 µg/L, Zn avg = 530 µg/L and Cu avg = 220 µg/L) sampling surveys, compared to the 1995 survey (TSS avg = 620 µg/L, Zn avg = 240 µg/L and Cu avg = 97 µg/L). However, no evident trend was observed between the 2003 and 2021 sampling surveys. The highest concentrations of Pb and Cd were observed in snow samples from the 1994-95 sampling survey (Pb max = 570 µg/L, Cd max = 4.6 µg/L). Results indicated higher concentrations of the pollutants studied in the city centre, compared to the residential suburbs, and in areas with heavier traffic, where concentrations of metals correlated well with traffic intensity. Fractionation analysis of trace metals indicated that Zn, Cu and Pb occurred mostly in the particulate-bound phase (>0.45 µm) containing the most of Zn, Cu, and Pb mass, at 80, 84 and 94% of the total, respectively. Over 50% of the dissolved phase of Zn and Cu was in the truly dissolved fraction (<3000 MWCO). Concentrations of PAHs also increased with traffic intensity, with pyrene being the most frequently detected PAH, likely because of the strength of sources and various physical processes influencing the snowbanks development and causing spatial and temporal variations in pollutant concentrations.


Assuntos
Poluentes Ambientais , Metais Pesados , Oligoelementos , Metais Pesados/análise , Cádmio/análise , Estações do Ano , Neve , Suécia , Chumbo/análise , Oligoelementos/análise , Poluentes Ambientais/análise , Monitoramento Ambiental
15.
Chemosphere ; 350: 141081, 2024 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-38160952

RESUMO

The chemical reactivity of trace elements (TEs) in dusts from bitumen mining, upgrading and related industrial activities in the Athabasca Bituminous Sands region (ABS), Alberta, Canada, was evaluated using the acid-soluble fraction of snow. Samples were collected at 14 sites along the Athabasca River (AR) and its tributaries, and at 3 remote locations. Following metal-free, ultra-clean procedures for processing and analysis, samples were leached with nitric acid (pH < 1), filtered (<0.45 µm), and analyzed using ICP-MS. Insoluble particles (>0.45 µm) were examined using SEM-EDS. Along the river, acid-soluble concentrations of TEs varied by 6 orders of magnitude, from 1 mg/L (Al) to less than 1 ng/L (Tl). Conservative (Al, Y, La, Th) and mobile (Li, Be, Cs, Sr) lithophile elements, those enriched in bitumen (V, Ni, Mo), and potentially toxic chalcophile elements (As, Cd, Pb, Sb, Tl) showed considerable spatial variation. Normalizing the concentrations of TEs in samples collected near industry to the corresponding concentrations in snow from the reference site (UTK), resulted in enrichments of V and most of the lithophile elements. Dust reactivity, quantified as the ratio of acid-soluble to total concentrations, was less than 50% suggesting limited bioaccessibility. The large differences in behaviour between Cd and Pb versus Ni and V could be due to the occurrence of the former pair in carbonate or sulfide minerals, versus acid-insoluble petcoke particles for the latter couple. Spatial variations in the reactivity of TEs most likely reflect the range in diversity and chemical stability of dust particles, and variations in their abundance in primary source areas. The leaching conditions employed here are extreme (pH < 1) and intended to identify an upper limit of chemical reactivity, with far less dust dissolution expected when these dusts encounter natural waters of the area which range in pH from 4 to 8.


Assuntos
Poeira , Hidrocarbonetos , Oligoelementos , Poeira/análise , Oligoelementos/análise , Monitoramento Ambiental , Neve , Cádmio/análise , Chumbo/análise , Alberta
16.
Sci Data ; 10(1): 863, 2023 12 04.
Artigo em Inglês | MEDLINE | ID: mdl-38049456

RESUMO

The current methods for designing hydrological infrastructure rely on precipitation-based intensity-duration-frequency curves. However, they cannot accurately predict flooding caused by snowmelt or rain-on-snow events, potentially leading to underdesigned infrastructure and property damage. To address these issues, next-generation intensity-duration-frequency (NG-IDF) curves have been developed for the open condition, characterizing water available for runoff from rainfall, snowmelt, and rain-on-snow. However, they lack consideration of land use land cover (LULC) factors, which can significantly affect runoff processes. We address this limitation by expanding open area NG-IDF dataset to include eight vegetated LULCs over the continental United States, including forest (deciduous, evergreen, mixed), shrub, grass, pasture, crop, and wetland. This NG-IDF 2.0 dataset offers a comprehensive analysis of hydrological extreme events and their associated drivers under different LULCs at a continental scale. It will serve as a useful resource for improving standard design practices and aiding in the assessment of infrastructure design risks. Additionally, it provides useful insights into how changes in LULC impact flooding magnitude, mechanisms, timing, and snow water supply.


Assuntos
Chuva , Movimentos da Água , Hidrologia , Neve , Florestas
17.
Extremophiles ; 28(1): 3, 2023 Nov 14.
Artigo em Inglês | MEDLINE | ID: mdl-37962679

RESUMO

Snow is a unique microhabitat, despite being a harsh environment, multiple life forms have adapted to survive in it. While algae, bacteria and fungi are dominant microorganisms in Antarctic snow, little is known about other organisms that may be present in this habitat. We used metabarcoding to investigate DNA sequence diversity of non-fungal eukaryotes present in snow obtained from six different sites across the Maritime Antarctica. A total of 20 taxa were assigned to obtained sequences, representing five Kingdoms (Chromista, Protozoa, Viridiplantae and Metazoa) and four phyla (Ciliophora, Cercozoa, Chlorophyta and Cnidaria). The highest diversity indices were detected in Trinity Peninsula followed by Robert Island, Arctowski Peninsula, Deception Island, King George Island and Snow Island. The most abundant assignments were to Trebouxiophyceae, followed by Chlamydomonas nivalis and Chlamidomonadales. No taxa were detected at all sites. Three potentially new records for Antarctica were detected: two Ciliophora (Aspidisca magna and Stokesia sp.) and the green algae Trebouxia potteri. Our data suggested that similarities found between the sites may be more related with snow physicochemical properties rather than geographic proximity or latitude. This study provides new insights into the diversity and distribution of eukaryotic organisms in Antarctic snow.


Assuntos
Chlamydomonas , Neve , Regiões Antárticas , Código de Barras de DNA Taxonômico , DNA
18.
Nat Commun ; 14(1): 7500, 2023 11 18.
Artigo em Inglês | MEDLINE | ID: mdl-37980360

RESUMO

Sanguina nivaloides is the main alga forming red snowfields in high mountains and Polar Regions. It is non-cultivable. Analysis of environmental samples by X-ray tomography, focused-ion-beam scanning-electron-microscopy, physicochemical and physiological characterization reveal adaptive traits accounting for algal capacity to reside in snow. Cysts populate liquid water at the periphery of ice, are photosynthetically active, can survive for months, and are sensitive to freezing. They harbor a wrinkled plasma membrane expanding the interface with environment. Ionomic analysis supports a cell efflux of K+, and assimilation of phosphorus. Glycerolipidomic analysis confirms a phosphate limitation. The chloroplast contains thylakoids oriented in all directions, fixes carbon in a central pyrenoid and produces starch in peripheral protuberances. Analysis of cells kept in the dark shows that starch is a short-term carbon storage. The biogenesis of cytosolic droplets shows that they are loaded with triacylglycerol and carotenoids for long-term carbon storage and protection against oxidative stress.


Assuntos
Cistos , Neve , Humanos , Cloroplastos/metabolismo , Cistos/metabolismo , Carbono/metabolismo , Amido/metabolismo
19.
FEMS Microbiol Ecol ; 99(12)2023 Nov 13.
Artigo em Inglês | MEDLINE | ID: mdl-37880981

RESUMO

Melting snow and glacier surfaces host microalgal blooms in polar and mountainous regions. The aim of this study was to determine the dominant taxa at the species level in the European Arctic and the Alps. A standardized protocol for amplicon metabarcoding using the 18S rRNA gene and ITS2 markers was developed. This is important because previous biodiversity studies have been hampered by the dominance of closely related algal taxa in snow and ice. Due to the limited resolution of partial 18S rRNA Illumina sequences, the hypervariable ITS2 region was used to further discriminate between the genotypes. Our results show that red snow was caused by the cosmopolitan Sanguina nivaloides (Chlamydomonadales, Chlorophyta) and two as of yet undescribed Sanguina species. Arctic orange snow was dominated by S. aurantia, which was not found in the Alps. On glaciers, at least three Ancylonema species (Zygnematales, Streptophyta) dominated. Golden-brown blooms consisted of Hydrurus spp. (Hydrurales, Stramenophiles) and these were mainly an Arctic phenomenon. For chrysophytes, only the 18S rRNA gene but not ITS2 sequences were amplified, showcasing how delicate the selection of eukaryotic 'universal' primers for community studies is and that primer specificity will affect diversity results dramatically. We propose our approach as a 'best practice'.


Assuntos
Clorofíceas , Clorófitas , Camada de Gelo , Neve , RNA Ribossômico 18S/genética , Genes de RNAr , Clorófitas/genética , Clorofíceas/genética
20.
Mol Genet Genomics ; 298(6): 1449-1466, 2023 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-37815644

RESUMO

Phacidium infestans (synonym Gremmenia infestans) is a significant pathogen that impacts Pinus species across the northern regions of Europe and Asia. This study introduces the genome sequence of P. infestans Karsten DSM 5139 (Phain), obtained through Pacbio technology. The assembly resulted in 44 contigs, with a total genome size of 36,805,277 bp and a Guanine-Cytosine content of 46.4%. Genome-mining revealed numerous putative biosynthetic gene clusters that code for virulence factors and fungal toxins. The presence of the enzyme pisatin demethylase was indicative of the potential of Phain to detoxify its environment from the terpenoid phytoalexins produced by its host as a defense mechanism. Proteomic analysis revealed the potential survival strategies of Phain under the snow, which included the production of antifreeze proteins, trehalose synthesis enzymes, desaturases, proteins related to elongation of very long-chain fatty acids, and stress protein responses. Study of protein GH11 endoxylanase expressed in Escherichia coli showed an acidic optimum pH (pH 5.0) and a low optimum temperature (45 °C), which is reflective of the living conditions of the fungus. Mass spectrometry analysis of the methanol extract of Phain, incubated at - 3 °C and 22 °C, revealed differences in the produced metabolites. Both genomic and mass spectrometry analyses showed the ability of Phain to adapt its metabolic processes and secretome to freezing temperatures through the production of osmoprotectant and cryoprotectant metabolites. This comprehensive exploration of Phain's genome sequence, proteome, and secretome not only advances our understanding of its unique adaptive mechanisms but also expands the possibilities of biotechnological applications.


Assuntos
Proteômica , Neve , Temperatura , Congelamento , Proteínas , Espectrometria de Massas , Fungos , Doenças das Plantas/microbiologia
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