Euglena longa, a close relative of the photosynthetic model alga Euglena gracilis, possesses an enigmatic non-photosynthetic plastid. Its genome has retained a gene for the large subunit of the enzyme RuBisCO (rbcL). Here we provide new data illuminating the putative role of RuBisCO in E. longa. We demonstrated that the E. longa RBCL protein sequence is extremely divergent compared to its homologs from the photosynthetic relatives, suggesting a possible functional shift upon the loss of photosynthesis. Similarly to E. gracilis, E. longa harbors a nuclear gene encoding the small subunit of RuBisCO (RBCS) as a precursor polyprotein comprising multiple RBCS repeats, but one of them is highly divergent. Both RBCL and the RBCS proteins are synthesized in E. longa, but their abundance is very low compared to E. gracilis. No RBCS monomers could be detected in E. longa, suggesting that processing of the precursor polyprotein is inefficient in this species. The abundance of RBCS is regulated post-transcriptionally. Indeed, blocking the cytoplasmic translation by cycloheximide has no immediate effect on the RBCS stability in photosynthetically grown E. gracilis, but in E. longa, the protein is rapidly degraded. Altogether, our results revealed signatures of evolutionary degradation (becoming defunct) of RuBisCO in E. longa and suggest that its biological role in this species may be rather unorthodox, if any.

• MeSH
• Euglena longa * enzymologie   genetika   MeSH
• protozoální proteiny * biosyntéza   genetika   MeSH
• regulace genové exprese enzymů fyziologie   MeSH
• ribulosa-1,5-bisfosfát-karboxylasa * biosyntéza   genetika   MeSH
• transkriptom fyziologie   MeSH
• Publikační typ
• časopisecké články MeSH

The present work has explored for the first time acclimation of upper versus lower canopy leaves along an altitudinal gradient. We tested the hypothesis that restrictive climatic conditions associated with high altitudes reduce within-canopy variations of leaf traits. The investigated beech (Fagus sylvatica L.) forest is located on the southern slope of the Hrubý Jeseník Mountains (Czech Republic). All measurements were taken on leaves from upper and lower parts of the canopy of mature trees (>85 years old) growing at low (400 m above sea level, a.s.l.), middle (720 m a.s.l.) and high (1100 m a.s.l.) altitudes. Compared with trees at higher altitudes, those growing at low altitudes had lower stomatal conductance, slightly lower CO(2) assimilation rate (A(max)) and leaf mass per area (LMA), and higher photochemical reflectance index, water-use efficiency and Rubisco content. Given similar stand densities at all altitudes, the different growth conditions result in a more open canopy and higher penetration of light into lower canopy with increasing altitude. Even though strong vertical gradients in light intensity occurred across the canopy at all altitudes, lower canopy leaves at high altitudes tended to acquire the same morphological, biochemical and physiological traits as did upper leaves. While elevation had no significant effect on nitrogen (N) and carbon (C) contents per unit leaf area, LMA, or total content of chlorophylls and epidermal flavonoids in upper leaves, these increased significantly in lower leaves at higher altitudes. The increases in N content of lower leaves were coupled with similar changes in A(max). Moreover, a high N content coincided with high Rubisco concentrations in lower but not in upper canopy leaves. Our results show that the limiting role of light in lower parts of the canopy is reduced at high altitudes. A great capacity of trees to adjust the entire canopy is thus demonstrated.

• MeSH
• buk (rod) anatomie a histologie   genetika   fyziologie   MeSH
• dusík analýza   MeSH
• fenotyp * MeSH
• fotosyntéza * MeSH
• listy rostlin anatomie a histologie   chemie   fyziologie   MeSH
• nadmořská výška * MeSH
• oxid uhličitý metabolismus   MeSH
• průduchy rostlin anatomie a histologie   fyziologie   MeSH
• ribulosa-1,5-bisfosfát-karboxylasa analýza   MeSH
• světlo MeSH
• uhlík analýza   MeSH
• voda metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

The distribution of microbial eukaryotes (protists) has been frequently discussed during the last two decades. The ubiquity hypothesis assumes the lack of latitudinal gradients in protist diversity due to their unlimited global dispersal. In this study, we examined the diversity and distribution of the very common, globally distributed green algal genus Klebsormidium across climatic zones, focusing on the polar regions. We tested whether (i) there is comparable diversity among the polar and temperate regions, and (ii) whether a spatial genetic differentiation occurs at the global scale. We collected a total of 58 Arctic, Antarctic and temperate strains, and genetically characterized them by sequencing the rbcL gene and two highly variable chloroplast markers. Our analyses revealed the presence of two different distribution patterns which are supposed to characterize both macroorganisms and protists. On the one hand, we demonstrated unlimited dispersal and intensive gene flow within one of the inferred lineages (superclade B). On the other hand, the majority of Klebsormidium clades showed rather a limited distribution. In addition, we detected a significant decrease of species richness towards the poles i.e. the macroecological pattern typical for macroorganisms. Species within a single protist genus may thus exhibit highly contrasting distribution patterns, based on their dispersal capabilities, which are usually shaped by both intrinsic and extrinsic factors.

• MeSH
• biodiverzita MeSH
• chloroplasty genetika   MeSH
• ribulosa-1,5-bisfosfát-karboxylasa genetika   MeSH
• Streptophyta klasifikace   genetika   MeSH
• studené klima MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Geografické názvy
• Antarktida MeSH
• Arktida MeSH

Despite considerable research attention during the last 10 years, the distribution and biogeography of protists remain as highly controversial issues. The presumably huge population sizes and unlimited dispersal capabilities should result in protist ubiquity. However, recent molecular investigations suggest that protist communities exhibit strong biogeographic patterns. Here, we examined the biogeographic pattern of a very common green algal genus Klebsormidium. We evaluated the geographic distribution of rbcL genotypes for 190 isolates sampled in six sampling regions located in Europe, North America and Asia. Measures of correlation between genetic and geographic distance matrices revealed a differential distribution pattern on two geographic levels. Globally, the populations were genetically homogeneous; locally, the genotypes were patchily distributed. We hypothesized that a local fine-scale structuring of genotypes may be caused by various ecological factors, in particular, by the habitat differentiation of particular genotypes. Our investigations also identified a large number of new, previously unrecognized lineages. A total of 44 genotypes were identified and more than 66% of these were reported for the first time.

• MeSH
• ekologie MeSH
• fylogeografie MeSH
• genetická variace genetika   MeSH
• genotyp MeSH
• ribulosa-1,5-bisfosfát-karboxylasa genetika   MeSH
• Streptophyta klasifikace   genetika   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Geografické názvy
• Asie MeSH
• Evropa MeSH
• Severní Amerika MeSH

While mechanisms of different carbon dioxide (CO2 ) assimilation pathways in chemolithoautotrohic prokaryotes are well understood for many isolates under laboratory conditions, the ecological significance of diverse CO2 fixation strategies in the environment is mostly unexplored. Six stratified freshwater lakes were chosen to study the distribution and diversity of the Calvin-Benson-Bassham (CBB) cycle, the reductive tricarboxylic acid (rTCA) cycle, and the recently discovered archaeal 3-hydroxypropionate/4-hydroxybutyrate (HP/HB) pathway. Eleven primer sets were used to amplify and sequence genes coding for selected key enzymes in the three pathways. Whereas the CBB pathway with different forms of RubisCO (IA, IC and II) was ubiquitous and related to diverse bacterial taxa, encompassing a wide range of potential physiologies, the rTCA cycle in Epsilonproteobacteria and Chloribi was exclusively detected in anoxic water layers. Nitrifiying Nitrosospira and Thaumarchaeota, using the rTCA and HP/HB cycle respectively, are important residents in the aphotic and (micro-)oxic zone of deep lakes. Both taxa were of minor importance in surface waters and in smaller lakes characterized by an anoxic hypolimnion. Overall, this study provides a first insight on how different CO2 fixation strategies and chemical gradients in lakes are associated to the distribution of chemoautotrophic prokaryotes with different functional traits.

• MeSH
• Archaea metabolismus   MeSH
• chemoautotrofní růst fyziologie   MeSH
• Chlorobi genetika   metabolismus   MeSH
• citrátový cyklus fyziologie   MeSH
• Epsilonproteobacteria genetika   metabolismus   MeSH
• fotosyntéza fyziologie   MeSH
• hydroxybutyráty metabolismus   MeSH
• jezera chemie   mikrobiologie   MeSH
• koloběh uhlíku fyziologie   MeSH
• kyselina mléčná analogy a deriváty   metabolismus   MeSH
• oxid uhličitý metabolismus   MeSH
• ribulosa-1,5-bisfosfát-karboxylasa genetika   metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH

BACKGROUND AND AIMS: Plants growing under elevated atmospheric CO2 concentrations often have reduced stomatal conductance and subsequently increased leaf temperature. This study therefore tested the hypothesis that under long-term elevated CO2 the temperature optima of photosynthetic processes will shift towards higher temperatures and the thermostability of the photosynthetic apparatus will increase. METHODS: The hypothesis was tested for saplings of broadleaved Fagus sylvatica and coniferous Picea abies exposed for 4-5 years to either ambient (AC; 385 µmol mol(-1)) or elevated (EC; 700 µmol mol(-1)) CO2 concentrations. Temperature response curves of photosynthetic processes were determined by gas-exchange and chlorophyll fluorescence techniques. KEY RESULTS: Initial assumptions of reduced light-saturated stomatal conductance and increased leaf temperatures for EC plants were confirmed. Temperature response curves revealed stimulation of light-saturated rates of CO2 assimilation (Amax) and a decline in photorespiration (RL) as a result of EC within a wide temperature range. However, these effects were negligible or reduced at low and high temperatures. Higher temperature optima (Topt) of Amax, Rubisco carboxylation rates (VCmax) and RL were found for EC saplings compared with AC saplings. However, the shifts in Topt of Amax were instantaneous, and disappeared when measured at identical CO2 concentrations. Higher values of Topt at elevated CO2 were attributed particularly to reduced photorespiration and prevailing limitation of photosynthesis by ribulose-1,5-bisphosphate (RuBP) regeneration. Temperature response curves of fluorescence parameters suggested a negligible effect of EC on enhancement of thermostability of photosystem II photochemistry. CONCLUSIONS: Elevated CO2 instantaneously increases temperature optima of Amax due to reduced photorespiration and limitation of photosynthesis by RuBP regeneration. However, this increase disappears when plants are exposed to identical CO2 concentrations. In addition, increased heat-stress tolerance of primary photochemistry in plants grown at elevated CO2 is unlikely. The hypothesis that long-term cultivation at elevated CO2 leads to acclimation of photosynthesis to higher temperatures is therefore rejected. Nevertheless, incorporating acclimation mechanisms into models simulating carbon flux between the atmosphere and vegetation is necessary.

• MeSH
• aklimatizace MeSH
• chlorofyl metabolismus   MeSH
• fotosyntéza účinky léků   fyziologie   MeSH
• fotosystém II (proteinový komplex) metabolismus   MeSH
• listy rostlin účinky léků   fyziologie   účinky záření   MeSH
• oxid uhličitý farmakologie   MeSH
• ribulosa-1,5-bisfosfát-karboxylasa metabolismus   MeSH
• ribulosafosfáty MeSH
• semenáček účinky léků   fyziologie   účinky záření   MeSH
• smrk účinky léků   fyziologie   účinky záření   MeSH
• světlo MeSH
• teplota MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

The traditional green algal genus Chloromonas accommodates mesophilic, cold-tolerant and cold-adapted microorganisms. In this paper, we studied a new strain isolated from a wet hummock meadow in the High Arctic. We used morphological, ultrastructural and molecular data to assess the taxonomic position and phylogenetic relationships of the new isolate. The observed morphological features generally corresponded to the cold-tolerant Chloromonas characteristics. However, ellipsoidal or wide ellipsoidal vegetative cells, a massive parietal cup-shaped chloroplast with a number of continuously connected lobes, a thick cell wall, a prominent hemispherical papilla and the anterior position of an oblong or round eyespot distinguished the alga from all previously described Chloromonas species. Analyses of rbcL and 18S rRNA genes showed that the new strain formed an independent lineage within a clade containing mesophilic and psychrotolerant Chloromonas species. Comparisons of secondary structure models of a highly variable ITS2 rDNA marker supported a separate species identity of the new isolate. Considering the morphological and molecular differences from its relatives, a new psychrotolerant species, Chloromonas svalbardensis, is proposed. Further, our results demonstrated the paraphyletic origin of Chloromonas within Chloromonadinia with genetically, morphologically and ecologically well-defined clades. We discuss a scenario of a possible Chloromonas split and revision.

• MeSH
• buněčná stěna ultrastruktura   MeSH
• Chlorophyceae klasifikace   cytologie   genetika   fyziologie   MeSH
• chloroplasty ultrastruktura   MeSH
• DNA rostlinná analýza   MeSH
• fylogeneze * MeSH
• ribozomální DNA genetika   MeSH
• ribulosa-1,5-bisfosfát-karboxylasa genetika   MeSH
• RNA ribozomální 18S genetika   MeSH
• rostlinné geny genetika   MeSH
• sníh MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Geografické názvy
• Arktida MeSH
• Norsko MeSH

The carnivorous plant genus Utricularia L. (bladderwort) comprises about 240 species distributed worldwide and is traditionally classified into two subgenera (Polypompholyx and Utricularia) and 35 sections, based mainly on general and trap morphology. It is one out of the largest carnivorous genera, representing ca. 30% of all carnivorous plant species, and is also the most widely distributed. According to previous phylogenetic studies, most infrageneric sections are monophyletic, but there are several incongruences considering their relationships and also the dissenting position of some species as a result of a too few (mostly one or two) molecular markers analyzed. Thus, here we present a multilocus phylogeny for Utricularia species with a wide taxonomic sampling (78 species and 115 accessions) based on six plastid (rbcL, matK, rpl20-rps12, rps16, trnL-F) and nuclear DNA (ITS region) sequences. The aim is to reconstruct a well-resolved tree to propose evolutionary and biogeographic hypotheses for the radiation of lineages with inferences about the divergence times of clades using a molecular clock approach.

• MeSH
• Bayesova věta MeSH
• biologická evoluce MeSH
• buněčné jádro genetika   MeSH
• DNA rostlinná chemie   izolace a purifikace   metabolismus   MeSH
• fylogeneze MeSH
• hluchavkotvaré klasifikace   genetika   MeSH
• plastidy genetika   MeSH
• ribulosa-1,5-bisfosfát-karboxylasa klasifikace   genetika   metabolismus   MeSH
• rostlinné proteiny klasifikace   genetika   metabolismus   MeSH
• sekvence nukleotidů MeSH
• sekvenční analýza DNA MeSH
• sekvenční seřazení MeSH
• Publikační typ
• časopisecké články MeSH

Two new genera (Streptosarcina and Streptofilum) and three new species (Streptosarcina arenaria, S. costaricana and Streptofilum capillatum) of streptophyte algae were detected in cultures isolated from terrestrial habitats of Europe and Central America and described using an integrative approach. Additionally, a strain isolated from soil in North America was identified as Hormidiella parvula and proposed as an epitype of this species. The molecular phylogeny based on 18S rRNA and rbcL genes, secondary structure of ITS-2, as well as the morphology of vegetative and reproductive stages, cell ultrastructure, ecology and distribution of the investigated strains were assessed. The new genus Streptosarcina forms a sister lineage to the genus Hormidiella (Klebsormidiophyceae). Streptosarcina is characterized by packet-like (sarcinoid) and filamentous thalli with true branching and a cell organization typical for Klebsormidiophyceae. Streptofilum forms a separate lineage within Streptophyta. This genus represents an easily disintegrating filamentous alga which exhibits a cell coverage of unique structure: layers of submicroscopic scales of piliform shape covering the plasmalemma and exfoliate inside the mucilage envelope surrounding cells. The implications of the discovery of the new taxa for understanding evolutionary tendencies in the Streptophyta, a group of great evolutionary interest, are discussed.

• MeSH
• DNA rostlinná chemie   genetika   MeSH
• ekosystém * MeSH
• fylogeneze * MeSH
• konformace nukleové kyseliny MeSH
• mezerníky ribozomální DNA chemie   genetika   MeSH
• mikroskopie MeSH
• půdní mikrobiologie MeSH
• ribozomální DNA chemie   genetika   MeSH
• ribulosa-1,5-bisfosfát-karboxylasa genetika   MeSH
• RNA ribozomální 18S genetika   MeSH
• sekvenční analýza DNA MeSH
• shluková analýza MeSH
• Streptophyta klasifikace   genetika   ultrastruktura   MeSH
• transmisní elektronová mikroskopie MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Geografické názvy
• Evropa MeSH
• Severní Amerika MeSH
• Střední Amerika MeSH