Heterotrophic nanoflagellates (HNF) are considered as major planktonic bacterivores, however, larger HNF taxa can also be important predators of eukaryotes. To examine this trophic cascading, natural protistan communities from a freshwater reservoir were released from grazing pressure by zooplankton via filtration through 10- and 5-µm filters, yielding microbial food webs of different complexity. Protistan growth was stimulated by amendments of five Limnohabitans strains, thus yielding five prey-specific treatments distinctly modulating protistan communities in 10- versus 5-µm fractions. HNF dynamics was tracked by applying five eukaryotic fluorescence in situ hybridization probes covering 55-90% of total flagellates. During the first experimental part, mainly small bacterivorous Cryptophyceae prevailed, with significantly higher abundances in 5-µm treatments. Larger predatory flagellates affiliating with Katablepharidacea and one Cercozoan lineage (increasing to up to 28% of total HNF) proliferated towards the experimental endpoint, having obviously small phagocytized HNF in their food vacuoles. These predatory flagellates reached higher abundances in 10-µm treatments, where small ciliate predators and flagellate hunters also (Urotricha spp., Balanion planctonicum) dominated the ciliate assemblage. Overall, our study reports pronounced cascading effects from bacteria to bacterivorous HNF, predatory HNF and ciliates in highly treatment-specific fashions, defined by both prey-food characteristics and feeding modes of predominating protists.
- MeSH
- Cercozoa * MeSH
- Cryptophyta MeSH
- hybridizace in situ fluorescenční MeSH
- potravní řetězec * MeSH
- sladká voda MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Elucidating trophic interactions, such as predation and its effects, is a frequent task for many researchers in ecology. The study of microbial communities has many limitations, and determining a predator, prey, and predatory rates is often difficult. Presented here is an optimized method based on the addition of fluorescently labelled prey as a tracer, which allows for reliable quantitation of the grazing rates in aquatic predatory eukaryotes and estimation of nutrient transfer to higher trophic levels.
- MeSH
- Bacteria metabolismus MeSH
- Eukaryota MeSH
- mikrobiologie vody * MeSH
- mikrobiota * MeSH
- potravní řetězec * MeSH
- predátorské chování * MeSH
- řeky MeSH
- Tetrahymena fyziologie MeSH
- uhlík metabolismus MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- audiovizuální média MeSH
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Geografické názvy
- Česká republika MeSH
Trap fluid of aquatic carnivorous plants of the genus Utricularia hosts specific microbiomes consisting of commensal pro- and eukaryotes of largely unknown ecology. We examined the characteristics and dynamics of bacteria and the three dominant eukaryotes, i.e. the algae-bearing ciliate Tetrahymena utriculariae (Ciliophora), a green flagellate Euglena agilis (Euglenophyta), and the alga Scenedesmus alternans (Chlorophyta), associated with the traps of Utricularia reflexa. Our study focused on ecological traits and life strategies of the highly abundant ciliate whose biomass by far exceeds that of other eukaryotes and bacteria independent of the trap age. The ciliate was the only bacterivore in the traps, driving rapid turnover of bacterial standing stock. However, given the large size of the ciliate and the cell-specific uptake rates of bacteria we estimated that bacterivory alone would likely be insufficient to support its apparent rapid growth in traps. We suggest that mixotrophy based on algal symbionts contributes significantly to the diet and survival strategy of the ciliate in the extreme (anaerobic, low pH) trap-fluid environment. We propose a revised concept of major microbial interactions in the trap fluid where ciliate bacterivory plays a central role in regeneration of nutrients bound in rapidly growing bacterial biomass.
- MeSH
- anaerobióza MeSH
- Bacteria MeSH
- biomasa MeSH
- Chlorophyta MeSH
- Ciliophora fyziologie MeSH
- ekologie * MeSH
- koncentrace vodíkových iontů MeSH
- Magnoliopsida chemie růst a vývoj mikrobiologie parazitologie MeSH
- mikrobiální společenstva MeSH
- stadia vývoje MeSH
- symbióza fyziologie MeSH
- Tetrahymena růst a vývoj fyziologie MeSH
- Publikační typ
- časopisecké články MeSH
Different bacterial strains can have different value as food for heterotrophic nanoflagellates (HNF), thus modulating HNF growth and community composition. We examined the influence of prey food quality using four Limnohabitans strains, one Polynucleobacter strain and one freshwater actinobacterial strain on growth (growth rate, length of lag phase and growth efficiency) and community composition of a natural HNF community from a freshwater reservoir. Pyrosequencing of eukaryotic small subunit rRNA amplicons was used to assess time-course changes in HNF community composition. All four Limnohabitans strains and the Polynucleobacter strain yielded significant HNF community growth while the actinobacterial strain did not although it was detected in HNF food vacuoles. Notably, even within the Limnohabitans strains we found significant prey-related differences in HNF growth parameters, which could not be related only to size of the bacterial prey. Sequence data characterizing the HNF communities showed also that different bacterial prey items induced highly significant differences in community composition of flagellates. Generally, Stramenopiles dominated the communities and phylotypes closely related to Pedospumella (Chrysophyceae) were most abundant bacterivorous flagellates rapidly reacting to addition of the bacterial prey of high food quality.
- MeSH
- Actinobacteria fyziologie MeSH
- Burkholderiaceae fyziologie MeSH
- časové faktory MeSH
- Comamonadaceae fyziologie MeSH
- Eukaryota růst a vývoj metabolismus fyziologie MeSH
- fyziologie bakterií MeSH
- geny rRNA genetika MeSH
- heterotrofní procesy MeSH
- potravní řetězec MeSH
- sladká voda mikrobiologie MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
We examined the proportions of major Betaproteobacteria subgroups within bacterial communities in diverse nonaxenic, monospecific cultures of algae or cyanobacteria: four species of cryptophyta (genera Cryptomonas and Rhodomonas), four species of chlorophyta (genera Pediastrum, Staurastrum, and Chlamydomonas), and two species of cyanobacteria (genera Dolichospermum and Aphanizomenon). In the cryptophyta cultures, Betaproteobacteria represented 48 to 71% of total bacteria, the genus Limnohabitans represented 18 to 26%, and the Polynucleobacter B subcluster represented 5 to 16%. In the taxonomically diverse chlorophyta group, the genus Limnohabitans accounted for 7 to 45% of total bacteria. In contrast, cyanobacterial cultures contained significantly lower proportions of the Limnohabitans bacteria (1 to 3% of the total) than the cryptophyta and chlorophyta cultures. Notably, largely absent in all of the cultures was Polynucleobacter necessarius (Polynucleobacter C subcluster). Subsequently, we examined the growth of Limnohabitans strains in the presence of different algae or their extracellular products (EPP). Two strains, affiliated with Limnohabitans planktonicus and Limnohabitans parvus, were separately inoculated into axenic cultures of three algal species growing in an inorganic medium: Cryptomonas sp., Chlamydomonas noctigama, and Pediastrum boryanum. The Limnohabitans strains cocultured with these algae or inoculated into their EPP consistently showed (i) pronounced population growth compared to the control without the algae or EPP and (ii) stronger growth stimulation of L. planktonicus than of L. parvus. Overall, growth responses of the Limnohabitans strains cultured with algae were highly species specific, which suggests a pronounced niche separation between two closely related Limnohabitans species likely mediated by different abilities to utilize the substrates produced by different algal species.
- MeSH
- Betaproteobacteria klasifikace genetika růst a vývoj metabolismus MeSH
- Chlorophyta chemie MeSH
- Cryptophyta chemie MeSH
- ekosystém MeSH
- hybridizace in situ fluorescenční MeSH
- mikrobiologie životního prostředí MeSH
- sinice chemie MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
We investigated potential niche separation in two closely related (99.1% 16S rRNA gene sequence similarity) syntopic bacterial strains affiliated with the R-BT065 cluster, which represents a subgroup of the genus Limnohabitans. The two strains, designated B4 and D5, were isolated concurrently from a freshwater reservoir. Differences between the strains were examined through monitoring interactions with a bacterial competitor, Flectobacillus sp. (FL), and virus- and predator-induced mortality. Batch-type cocultures, designated B4+FL and D5+FL, were initiated with a similar biomass ratio among the strains. The proportion of each cell type present in the cocultures was monitored based on clear differences in cell sizes. Following exponential growth for 28 h, the cocultures were amended by the addition of two different concentrations of live or heat-inactivated viruses concentrated from the reservoir. Half of virus-amended treatments were inoculated immediately with an axenic flagellate predator, Poterioochromonas sp. The presence of the predator, of live viruses, and of competition between the strains significantly affected their population dynamics in the experimentally manipulated treatments. While strains B4 and FL appeared vulnerable to environmental viruses, strain D5 did not. Predator-induced mortality had the greatest impact on FL, followed by that on D5 and then B4. The virus-vulnerable B4 strain had smaller cells and lower biomass yield, but it was less subject to grazing. In contrast, the seemingly virus-resistant D5, with slightly larger grazing-vulnerable cells, was competitive with FL. Overall, our data suggest contrasting ecophysiological capabilities and partial niche separation in two coexisting Limnohabitans strains.
The distribution of the phylogenetically narrow R-BT065 cluster (Betaproteobacteria) in 102 freshwater lakes, reservoirs, and various ponds located in central Europe (a total of 122 samples) was examined by using a cluster-specific fluorescence in situ hybridization probe. These habitats differ markedly in pH, conductivity, trophic status, surface area, altitude, bedrock type, and other limnological characteristics. Despite the broad ecological diversity of the habitats investigated, the cluster was detected in 96.7% of the systems, and its occurrence was not restricted to a certain habitat type. However, the relative proportions of the cluster in the total bacterioplankton were significantly lower in humic and acidified lakes than in pH-neutral or alkaline habitats. On average, the cluster accounted for 9.4% of the total bacterioplankton (range, 0 to 29%). The relative abundance and absolute abundance of these bacteria were significantly and positively related to higher pH, conductivity, and the proportion of low-molecular-weight compounds in dissolved organic carbon (DOC) and negatively related to the total DOC and dissolved aromatic carbon contents. Together, these parameters explained 55.3% of the variability in the occurrence of the cluster. Surprisingly, no clear relationship of the R-BT065 bacteria to factors indicating the trophic status of habitats (i.e., different forms of phosphorus and chlorophyll a content) was found. Based on our results and previously published data, we concluded that the R-BT065 cluster represents a ubiquitous, highly active segment of bacterioplankton in nonacidic lakes and ponds and that alga-derived substrates likely form the main pool of substrates responsible for its high growth potential and broad distribution in freshwater habitats.
- MeSH
- Betaproteobacteria klasifikace genetika izolace a purifikace MeSH
- chlorofyl analýza MeSH
- DNA bakterií chemie MeSH
- ekosystém MeSH
- Eukaryota genetika MeSH
- fosfor analýza MeSH
- fylogeneze MeSH
- genetická variace MeSH
- hybridizace in situ fluorescenční MeSH
- mikrobiologie vody MeSH
- nadmořská výška MeSH
- počet mikrobiálních kolonií MeSH
- ribozomální DNA genetika MeSH
- RNA ribozomální 16S genetika MeSH
- RNA ribozomální 18S genetika MeSH
- sekvenční analýza DNA MeSH
- shluková analýza MeSH
- skleníkový efekt MeSH
- sladká voda chemie mikrobiologie MeSH
- uhlík analýza MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Geografické názvy
- Evropa MeSH
Endoskopické vyšetřovací metody dutých orgánů, podobně jako jiné invazivní výkony, jsou zatíženy určitým procentem někdy i velmi závažných komplikací. latrogenní perforace tlustého střeva, především přímo při výkonu, patří mezi ty nejdramatičtější. V období 1990-2000 jsme měli možnost ve spolupráci s interním oddělením řešit pět případů.
Endoscopic examinations of hollow organs, similarly as other invasive operations, are associated with a certain percentage of sometimes very serious complications. Iatrogenic perforations of the gut, in particular during the procedure belong to the most dramatic ones. During the period of 1990-2000 the authors had the opportunity to deal in collaboration with the medical department with five cases.
- MeSH
- iatrogenní nemoci MeSH
- kolon zranění MeSH
- kolonoskopie škodlivé účinky MeSH
- lidé MeSH
- perforace střeva etiologie terapie MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- kazuistiky MeSH
Rozestup laparotomické rány je vždy nepríjemnou událostí, počínaje rozladěním pacienta a vznikem jeho nedůvěry až po úplnou negaci príznivého operačního výsledku. Pri nedostatku vhodnějších materiálů jsme asi před 10 lety vypracovali vlastní techniku, kterou dnes využíváme jak léčebně, tak, a to především, preventivně. Domníváme se, že by mohla být určitým prínosem pro svou jednoduchost a finanční dostupnost.
Dehiscence of laparotomic wounds is always unpleasant, starting with the resentment of the patient and the lack of confidence leading as far as complete negation of a favourable result of the operation. Due to lack of more suitable materials we elaborated ten years ago our own technique which we use nowadays for treatment but in particular for prevention. We feel that it could be a certain asset because it is simple and financially feasible.
