BACKGROUND: Protists are essential contributors to eukaryotic diversity and exert profound influence on carbon fluxes and energy transfer in freshwaters. Despite their significance, there is a notable gap in research on protistan dynamics, particularly in the deeper strata of temperate lakes. This study aimed to address this gap by integrating protists into the well-described spring dynamics of Římov reservoir, Czech Republic. Over a 2-month period covering transition from mixing to established stratification, we collected water samples from three reservoir depths (0.5, 10 and 30 m) with a frequency of up to three times per week. Microbial eukaryotic and prokaryotic communities were analysed using SSU rRNA gene amplicon sequencing and dominant protistan groups were enumerated by Catalysed Reporter Deposition-Fluorescence in situ Hybridization (CARD-FISH). Additionally, we collected samples for water chemistry, phyto- and zooplankton composition analyses. RESULTS: Following the rapid changes in environmental and biotic parameters during spring, protistan and bacterial communities displayed swift transitions from a homogeneous community to distinct strata-specific communities. A prevalence of auto- and mixotrophic protists dominated by cryptophytes was associated with spring algal bloom-specialized bacteria in the epilimnion. In contrast, the meta- and hypolimnion showcased a development of a protist community dominated by putative parasitic Perkinsozoa, detritus or particle-associated ciliates, cercozoans, telonemids and excavate protists (Kinetoplastida), co-occurring with bacteria associated with lake snow. CONCLUSIONS: Our high-resolution sampling matching the typical doubling time of microbes along with the combined microscopic and molecular approach and inclusion of all main components of the microbial food web allowed us to unveil depth-specific populations' successions and interactions in a deep lentic ecosystem.

• Klíčová slova
• 18S and 16S amplicon sequencing, CARD-FISH, Epilimnion, Freshwater, Hypolimnion, Metalimnion, Microbial food webs, Protists, Spring succession,
• Publikační typ
• časopisecké články MeSH

BACKGROUND: The phytoplankton spring bloom in freshwater habitats is a complex, recurring, and dynamic ecological spectacle that unfolds at multiple biological scales. Although enormous taxonomic shifts in microbial assemblages during and after the bloom have been reported, genomic information on the microbial community of the spring bloom remains scarce. RESULTS: We performed a high-resolution spatio-temporal sampling of the spring bloom in a freshwater reservoir and describe a multitude of previously unknown taxa using metagenome-assembled genomes of eukaryotes, prokaryotes, and viruses in combination with a broad array of methodologies. The recovered genomes reveal multiple distributional dynamics for several bacterial groups with progressively increasing stratification. Analyses of abundances of metagenome-assembled genomes in concert with CARD-FISH revealed remarkably similar in situ doubling time estimates for dominant genome-streamlined microbial lineages. Discordance between quantitations of cryptophytes arising from sequence data and microscopic identification suggested the presence of hidden, yet extremely abundant aplastidic cryptophytes that were confirmed by CARD-FISH analyses. Aplastidic cryptophytes are prevalent throughout the water column but have never been considered in prior models of plankton dynamics. We also recovered the first metagenomic-assembled genomes of freshwater protists (a diatom and a haptophyte) along with thousands of giant viral genomic contigs, some of which appeared similar to viruses infecting haptophytes but owing to lack of known representatives, most remained without any indication of their hosts. The contrasting distribution of giant viruses that are present in the entire water column to that of parasitic perkinsids residing largely in deeper waters allows us to propose giant viruses as the biological agents of top-down control and bloom collapse, likely in combination with bottom-up factors like a nutrient limitation. CONCLUSION: We reconstructed thousands of genomes of microbes and viruses from a freshwater spring bloom and show that such large-scale genome recovery allows tracking of planktonic succession in great detail. However, integration of metagenomic information with other methodologies (e.g., microscopy, CARD-FISH) remains critical to reveal diverse phenomena (e.g., distributional patterns, in situ doubling times) and novel participants (e.g., aplastidic cryptophytes) and to further refine existing ecological models (e.g., factors affecting bloom collapse). This work provides a genomic foundation for future approaches towards a fine-scale characterization of the organisms in relation to the rapidly changing environment during the course of the freshwater spring bloom. Video Abstract.

• MeSH
• Bacteria MeSH
• Eukaryota genetika   MeSH
• metagenom * MeSH
• plankton MeSH
• sladká voda MeSH
• viry * genetika   MeSH
• voda MeSH
• Publikační typ
• audiovizuální média MeSH
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• voda MeSH

We studied the diversity of Limnohabitans using reverse line blot hybridization with Limnohabitans lineage-specific probes in the freshwater canyon-shaped Římov reservoir (Czech Republic). To examine the succession of distinct lineages, we performed (i) a study of an intensive spring sampling program at the lacustrine part of the Římov reservoir (from ice melt through a phytoplankton peak to the clear-water phase), and (ii) a seasonal study (April to November) when the occurrence of distinct Limnohabitans lineages was related to the inherent longitudinal heterogeneity of the reservoir. Significant spatiotemporal changes in the compositions of distinct Limnohabitans lineages allowed for the identification of "generalists" that were always present throughout the whole season as well as "specialists" that appeared in the reservoir only for limited periods of time or irregularly. Our results indicate that some phytoplankton groups, such as cryptophytes or cyanobacteria, and zooplankton composition were the major factors modulating the distribution and dynamics of distinct Limnohabitans lineages. The highest Limnohabitans diversity was observed during the spring algal bloom, whereas the lowest was during the summer cyanobacterial bloom. The microdiversity also markedly increased upstream in the reservoir, being highest at the inflow, and thus likely reflecting strong influences of the watershed.IMPORTANCE The genus Limnohabitans is a typical freshwater bacterioplankton and is believed to play a significant role in inland freshwater habitats. This work is unique in detecting and tracing different closely related lineages of this bacterial genus in its natural conditions using the semiquantitative reverse line blot hybridization method and in discovering the factors influencing the microdiversity, subtype alternations, and seasonality.

• Klíčová slova
• ITS, Limnohabitans, bacterial diversity, canyon-shaped freshwater reservoir, reverse line blot hybridization, subtypes,
• MeSH
• Comamonadaceae klasifikace   genetika   izolace a purifikace   MeSH
• Cryptophyta růst a vývoj   MeSH
• ekosystém MeSH
• eutrofizace MeSH
• fytoplankton růst a vývoj   MeSH
• roční období MeSH
• sinice růst a vývoj   MeSH
• sladká voda mikrobiologie   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Geografické názvy
• Česká republika MeSH

Here we explore the idea that keeping dead standing (marcescent) biomass plants can reduce its nutrient (N, P) content. Later after biomass falling to ground this may result in substantial changes in nutrient turnover with consequences for plant competitive interactions. To explore the effects standing dead biomass we used Calamagrostis epigejos as a model species. It is a common expansive grass, which after senescence retain a large proportion of the plant remains as dead standing biomass. We determined the biomass, N and P concentrations of living biomass, standing dead biomass, and lying dead biomass at young and old successional sites on the post-mining heap near Sokolov. Further, we analyzed nutrient budget in dead biomass during decomposition and we compared it with nutrient budget in decomposing cellulose. Concentrations of N and P in living biomass were highest in April and decreased during season. Lying dead biomass had a higher N concentration than N concentration contained in standing dead biomass. A litterbag experiment revealed that N was released from lying dead biomass but accumulated in standing dead biomass during decomposition. Similarly the N was accumulated in decomposing cellulose. This accumulation was highest in sites with low decomposition rate. In late summer and autumn lying biomass was derived from senescence plants, came to soil and N was released during decomposition potentially usable for C. epigejos. Standing dead biomass turned to lying biomass during winter and spring and then during its decomposition N was immobilized from soil. This mechanism could reduce availability of N for other plants and increase competitive advantage of C. epigejos regrowing from belowground organs during spring.

• Klíčová slova
• Aboveground-belowground-biotic-abiotic interactions, Biomass, Expansive grasses, Marcescence, Plant litter,
• MeSH
• biomasa * MeSH
• dusík analýza   MeSH
• fosfor analýza   MeSH
• lipnicovité fyziologie   MeSH
• monitorování životního prostředí * MeSH
• půda MeSH
• rostliny MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• dusík MeSH
• fosfor MeSH
• půda MeSH

BACKGROUND: Aerobic anoxygenic phototrophic (AAP) bacteria are heterotrophic bacteria that supply their metabolism with light energy harvested by bacteriochlorophyll-a-containing reaction centers. Despite their substantial contribution to bacterial biomass, microbial food webs, and carbon cycle, their phenology in freshwater lakes remains unknown. Hence, we investigated seasonal variations of AAP abundance and community composition biweekly across 3 years in a temperate, meso-oligotrophic freshwater lake. RESULTS: AAP bacteria displayed a clear seasonal trend with a spring maximum following the bloom of phytoplankton and a secondary maximum in autumn. As the AAP bacteria represent a highly diverse assemblage of species, we followed their seasonal succession using the amplicon sequencing of the pufM marker gene. To enhance the accuracy of the taxonomic assignment, we developed new pufM primers that generate longer amplicons and compiled the currently largest database of pufM genes, comprising 3633 reference sequences spanning all phyla known to contain AAP species. With this novel resource, we demonstrated that the majority of the species appeared during specific phases of the seasonal cycle, with less than 2% of AAP species detected during the whole year. AAP community presented an indigenous freshwater nature characterized by high resilience and heterogenic adaptations to varying conditions of the freshwater environment. CONCLUSIONS: Our findings highlight the substantial contribution of AAP bacteria to the carbon flow and ecological dynamics of lakes and unveil a recurrent and dynamic seasonal succession of the AAP community. By integrating this information with the indicator of primary production (Chlorophyll-a) and existing ecological models, we show that AAP bacteria play a pivotal role in the recycling of dissolved organic matter released during spring phytoplankton bloom. We suggest a potential role of AAP bacteria within the context of the PEG model and their consideration in further ecological models.

• Klíčová slova
• pufM gene, Aerobic anoxygenic phototrophs, Aquatic microbial ecology, Freshwaters, Long-term sampling, Microbial seasonal succession, PEG model, Photoheterotrophs,
• MeSH
• aerobní bakterie genetika   metabolismus   MeSH
• Bacteria genetika   MeSH
• biomasa MeSH
• fototrofní procesy * MeSH
• fytoplankton genetika   MeSH
• jezera * mikrobiologie   MeSH
• Publikační typ
• časopisecké články MeSH

In order to understand of the processes controlling phytoplankton successions in the NE Black Sea, long-term data series are needed. We compiled 15 years (2002-2017) of measurements from which the existence emerges of a tight link between phytoplankton species dominance and nutrients concentrations. The latter is strongly influenced by wind direction. The link between algal dominance and nutrients is mediated by the growth strategy adopted by algal species. In spring, when nutrients are abundant, small diatoms such as Pseudo-nitzschia pseudodelicatissima, with a "rapid growth strategy", prevail. In late spring and early summer, when N is low and P and Si are high, coccolithophorids such as Emiliania huxhleyi dominate, thanks to an "affinity growth strategy". Large diatoms, especially Pseudosolenia calcar-avis, dominate in summer and autumn, when their "storage growth strategy" allows the exploitation of discontinuous upwelling of nutrients. These seasonal changes of dominant species influence the structure of the food web.

• Klíčová slova
• Blooms, Ecological stoichiometry, Ecological succession, Nutrients, Phytoplankton, Wind,
• MeSH
• dusík analýza   MeSH
• eutrofizace * MeSH
• fosfor analýza   MeSH
• fytoplankton růst a vývoj   MeSH
• křemík analýza   MeSH
• monitorování životního prostředí MeSH
• mořská voda chemie   MeSH
• pohyb vody MeSH
• roční období MeSH
• rozsivky růst a vývoj   MeSH
• vítr MeSH
• živiny MeSH
• Publikační typ
• časopisecké články MeSH
• Geografické názvy
• Černé moře MeSH
• Názvy látek
• dusík MeSH
• fosfor MeSH
• křemík MeSH

BACKGROUND: Arthropod-borne viral encephalitis of diverse origins shows similar clinical symptoms, histopathology and magnetic resonance imaging, indicating that the patho mechanisms may be similar. There is no specific therapy to date. However, vaccination remains the best prophylaxis against a selected few. Regardless of these shortcomings, there are an increasing number of case reports that successfully treat arboviral encephalitis with high doses of intravenous immunoglobulins. DISCUSSION: To our knowledge, high dose intravenous immunoglobulin has not been tested systematically for treating severe cases of tick-borne encephalitis. Antibody-dependent enhancement has been suspected, but not proven, in several juvenile cases of tick-borne encephalitis. Although antibody-dependent enhancement during secondary infection with dengue virus has been documented, no adverse effects were noticed in a controlled study of high dose intravenous immunoglobulin therapy for dengue-associated thrombocytopenia. The inflammation-dampening therapeutic effects of generic high dose intravenous immunoglobulins may override the antibody-dependent enhancement effects that are potentially induced by cross-reactive antibodies or by virus-specific antibodies at sub-neutralizing levels. SUMMARY: Analogous to the increasing number of case reports on the successful treatment of other arboviral encephalitides with high dose intravenous immunoglobulins, we postulate whether it may be possible to also treat severe cases of tick-borne encephalitis with high dose intravenous immunoglobulins as early in the course of the disease as possible.

• MeSH
• intravenózní imunoglobuliny aplikace a dávkování   škodlivé účinky   imunologie   MeSH
• klíšťová encefalitida imunologie   terapie   virologie   MeSH
• lidé středního věku MeSH
• lidé MeSH
• protilátky virové aplikace a dávkování   škodlivé účinky   imunologie   MeSH
• Check Tag
• lidé středního věku MeSH
• lidé MeSH
• mužské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• kazuistiky MeSH
• práce podpořená grantem MeSH
• Názvy látek
• intravenózní imunoglobuliny MeSH
• protilátky virové MeSH

Competition affects mixed-mating strategies by limiting available abiotic or biotic resources such as nutrients, water, space, or pollinators. Cleistogamous species produce closed (cleistogamous, CL), obligately selfed, simultaneously with open (chasmogamous, CH), potentially outcrossed flowers. The effects of intraspecific competition on fitness and cleistogamy variation can range from limiting the production of costly CH flowers because of resource limitation, to favouring CH production because of fitness advantages of outcrossed, CH offspring. Moreover, the effects of competition can be altered when it co-occurs with other environmental variations. We grew plants from seven populations of the ruderal Lamium amplexicaule, originating from different climates and habitats, in a common garden experiment combining drought, interspecific competition, and seasonal variation. All these parameters have been shown to influence the degree of cleistogamy in the species on their own. In spring, competition and drought negatively impacted fitness, but the CL proportion only increased when plants were exposed to both treatments combined. We did not observe the same results in autumn, which can be due to non-adaptive phenotypic variation, or to differences in soil compactness between seasons. The observed responses are largely due to phenotypic plasticity, but we also observed phenotypic differentiation between populations for morphological, phenological, and cleistogamy traits, pointing to the existence of different ecotypes. Our data do not support the hypothesis that CL proportion should decrease when resources are scarce, as plants with reduced growth had relatively low CL proportions. We propose that variation in cleistogamy could be an adaptation to pollinator abundance, or to environment-dependent fitness differences between offspring of selfed and outcrossed seeds, two hypotheses worth further investigation. This opens exciting new possibilities for the study of the maintenance of mixed-mating systems using cleistogamous species as models that combine the effects of inbreeding and reproductive costs.

• Klíčová slova
• Lamium amplexicaule, cleistogamy, drought, ecotype, habitat succession, interspecific competition, mixed-mating, phenotypic plasticity, resource limitation,
• Publikační typ
• časopisecké články MeSH

In recent decades, global change and local anthropogenic pressures have severely affected natural ecosystems and their biodiversity. Although disentangling the effects of these factors is difficult, they are reflected in changes in the functional composition of plant communities. We present a comprehensive, large-scale analysis of long-term changes in plant communities of various non-forest habitat types in the Czech Republic based on 1154 vegetation-plot time series from 53 resurvey studies comprising 3909 vegetation-plot records. We focused not only on taxonomic diversity but also on the functional characteristics of communities. Species richness of most habitat types increased over time, and taxonomic and functional community composition shifted significantly. Habitat specialists and threatened species became less represented in plant communities, indicating a decline in habitat quality. The spread of trees, shrubs, tall herbaceous plants, strong competitors, and nutrient-demanding species in all non-forest habitats, coupled with the decline of light-demanding species, suggests an effect of eutrophication and natural succession following the abandonment of traditional management. Moreover, we identified specific trends in certain habitats. In wetlands, springs, and mires, moisture-demanding species decreased, probably due to drainage, river regulations, and increasing drought resulting from climate change. Dry grasslands, ruderal, weed, sand, and shallow-soil vegetation became more mesic, and successional processes were most pronounced in these communities, suggesting a stronger effect of abandonment of traditional management and eutrophication. In alpine and subalpine vegetation, meadows and mesic pastures, and heathlands, insect-pollinated species declined, and the proportion of grasses increased. Overall, these functional changes provide deep insights into the underlying drivers and help conservationists take appropriate countermeasures.

• Klíčová slova
• biodiversity change, drought, eutrophication, functional traits, habitat specialists, mesophilization, succession, vascular plants,
• MeSH
• biodiverzita * MeSH
• ekosystém * MeSH
• klimatické změny MeSH
• rostliny * klasifikace   MeSH
• zachování přírodních zdrojů MeSH
• Publikační typ
• časopisecké články MeSH
• Geografické názvy
• Česká republika MeSH

OBJECTIVE: In aseptic neuroinfections, the etiology is usually known in 50-70% of cases. The aim was to increase the rates using electron microscopy (EM) and virus isolation in cell cultures. MATERIAL AND METHODS: The prospective study included 34 patients with aseptic neuroinfections hospitalized at the Department of Infectious Diseases in Ostrava fromJuly to November 2012. EM examined cerebrospinal fluid of all patients and virus isolation in tissue cultures was performed in all cerebrospinal fluid samples. Cerebrospinal fluid was examined by polymerase chain reaction for enteroviruses in 30 patients and for herpes simplex virus 1 and 2 in 29 patients. Detection of antibodies against Borrelia burgdorferi and tick-borne encephalitis was performed in all 34 patients. RESULTS: Possible etiological agents were discovered in 31 out of 34 patients (91%), with one agent being found in 23 patients (68%) and two agents being detected in 8 patients (24%). EM revealed the agents in 26 patients and virus isolation was successful in 10 patients. EM was the only method to identify 10 agents. A group of 23 patients with a single agent detected included 14 patients with enteroviral meningitis, 4 patients with Lyme borreliosis and 4 patients with tick-borne encephalitis; EM detected an undefined virus in the last patient. An unusual group of 8 patients with two agents detected comprised 5 patients with enteroviruses and spirochetes, 2 patients with tick-borne encephalitis and undefined viruses and 1 patient with a spirochete and an undetermined virus. CONCLUSION: EM can aid in explaining the etiology of aseptic neuroinfections. However, the clinical interpretation of results remains problematic, such as detection of unknown viruses or two possible agents in 8 out of 34 patients.

• MeSH
• Borrelia burgdorferi izolace a purifikace   ultrastruktura   MeSH
• elektronová mikroskopie MeSH
• enterovirové infekce diagnóza   virologie   MeSH
• Enterovirus izolace a purifikace   ultrastruktura   MeSH
• klíšťová encefalitida diagnóza   virologie   MeSH
• lidé MeSH
• lymeská nemoc diagnóza   virologie   MeSH
• meningitida virová diagnóza   virologie   MeSH
• prospektivní studie MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH