Macrophytes have often been considered as a prospective tool for the elimination of cyanobacterial bloom, because they may produce chemical compounds that outcompete bloom-forming cyanobacteria. However, a comprehensive, unbiased overview of evidence to support this is missing. Moreover, studies into the effects of individual macrophyte species have often used different methodologies and, thus, cannot be compared. Herein, we firstly carried out a systematic review of studies into the effects of macrophytes on the growth of bloom-forming cyanobacteria. Secondly, we carried out an experiment into the effects of aqueous and ethanol extracts from 19 macrophyte species on the growth of two of the most common cyanobacteria, Aphanizomenon gracile and Microcystis aeruginosa, using a uniform methodological approach. The systematic review revealed that most of the 69 macrophyte species previously studied have shown a combination of inhibitory, stimulatory, and neutral effects. In our own experiment, an inhibitory effect was exhibited only 15 times out of 532 experimental variants, specifically by Chara globularis, Ceratophyllum submersum, Elodea nuttallii, Hydrilla verticillata, Myriophyllum heterophyllum, M. spicatum, and Vallisneria americana. Put together, these results indicate that the practical application of chemical compounds produced by macrophytes to eliminate cyanobacterial bloom may have lower prospects than previously anticipated.

• Klíčová slova
• Aquatic plant, Blue-green algae, Cyanocide, Water bloom,
• MeSH
• Aphanizomenon * MeSH
• Hydrocharitaceae * MeSH
• Microcystis * MeSH
• sinice * MeSH
• Publikační typ
• časopisecké články MeSH
• systematický přehled MeSH

Marine representatives of Phytomyxea (SAR: Rhizaria: Endomyxa), a peculiar class of obligate endobiotic parasites, are a greatly understudied ecological group of protists infecting many algal, diatom, and seagrass species. Very little is known about the actual diversity, ecology, and pathogenic potential of these organisms and their taxonomic treatment in many cases follows outdated morphotaxonomic concepts. Here we focused on resolving the phylogenetic relations of the phytomyxean parasites of the widespread seagrass genus Halophila. We report the first finding of Plasmodiophora halophilae, the parasite of ovate-leaf Halophila species, after more than 100 years since its original description in 1913. We provide additional information on its anatomy, morphology, distribution, and host range, together with a phylogenetic evidence that it is congeneric with the recently rediscovered species infecting the invasive seagrass Halophila stipulacea in the Mediterranean Sea. Despite the previously hypothesized affiliation of the latter to Tetramyxa, our phylogenetic analyses of the 18S rRNA gene place Tetramyxa parasitica (a parasite of brackish water phanerogams and the type species of the genus) in the freshwater/terrestrial phytomyxean order Plasmodiophorida and reveal that phytomyxids associated with Halophila spp. form a separate deep-branching clade within the class proposed here as Marinomyxa gen. nov. We further argue that M. marina infecting H. stipulacea is most likely a species-specific parasite and implies their comigration through the Suez Canal.

• Klíčová slova
• 18S rRNA phylogeny, Phytomyxids, Plasmodiophora halophilae, Seagrass symbionts, TAGIRI-5, Tetramyxa marina,
• MeSH
• fylogeneze MeSH
• Hydrocharitaceae * MeSH
• paraziti * MeSH
• Rhizaria * MeSH
• RNA ribozomální 18S genetika   MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• RNA ribozomální 18S MeSH

Vacuolar myelinopathy is a fatal neurological disease that was initially discovered during a mysterious mass mortality of bald eagles in Arkansas in the United States. The cause of this wildlife disease has eluded scientists for decades while its occurrence has continued to spread throughout freshwater reservoirs in the southeastern United States. Recent studies have demonstrated that vacuolar myelinopathy is induced by consumption of the epiphytic cyanobacterial species Aetokthonos hydrillicola growing on aquatic vegetation, primarily the invasive Hydrilla verticillata Here, we describe the identification, biosynthetic gene cluster, and biological activity of aetokthonotoxin, a pentabrominated biindole alkaloid that is produced by the cyanobacterium A. hydrillicola We identify this cyanobacterial neurotoxin as the causal agent of vacuolar myelinopathy and discuss environmental factors-especially bromide availability-that promote toxin production.

• MeSH
• Accipitridae * MeSH
• bakteriální geny MeSH
• bakteriální toxiny biosyntéza   chemie   izolace a purifikace   toxicita   MeSH
• brom analýza   MeSH
• bromidy metabolismus   MeSH
• Caenorhabditis elegans účinky léků   MeSH
• dánio pruhované MeSH
• demyelinizační nemoci chemicky indukované   veterinární   MeSH
• Hydrocharitaceae metabolismus   mikrobiologie   MeSH
• indolové alkaloidy chemie   izolace a purifikace   toxicita   MeSH
• kur domácí MeSH
• LD50 MeSH
• multigenová rodina MeSH
• nemoci ptáků chemicky indukované   MeSH
• neurotoxiny biosyntéza   chemie   izolace a purifikace   toxicita   MeSH
• sinice * genetika   růst a vývoj   metabolismus   MeSH
• tryptofan metabolismus   MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Research Support, N.I.H., Extramural MeSH
• Research Support, U.S. Gov't, P.H.S. MeSH
• Geografické názvy
• jihovýchod USA MeSH
• Názvy látek
• bakteriální toxiny MeSH
• brom MeSH
• bromidy MeSH
• indolové alkaloidy MeSH
• neurotoxiny MeSH
• tryptofan MeSH

Marine phytomyxids represent often overlooked obligate biotrophic parasites colonizing diatoms, brown algae, and seagrasses. An illustrative example of their enigmatic nature is the phytomyxid infecting the seagrass Halophila stipulacea (a well-known Lessepsian migrant from the Indo-Pacific to the Mediterranean Sea). In the Mediterranean, the occurrence of this phytomyxid was first described in 1995 in the Strait of Messina (southern Italy) and the second time in 2017 in the Aegean coast of Turkey. Here we investigated, using scuba diving, stereomicroscopy, light and scanning electron microscopy, and molecular methods, whether the symbiosis is still present in southern Italy, its distribution in this region and its relation to the previous reports. From the total of 16 localities investigated, the symbiosis has only been found at one site. A seasonal pattern was observed with exceptionally high abundance (> 40% of the leaf petioles colonized) in September 2017, absence of the symbiosis in May/June 2018, and then again high infection rates (~ 30%) in September 2018. In terms of anatomy and morphology as well as resting spore dimensions and arrangement, the symbiosis seems to be identical to the preceding observations in the Mediterranean. According to the phylogenetic analyses of the 18S rRNA gene, the phytomyxid represents the first characterized member of the environmental clade "TAGIRI-5". Our results provide new clues about its on-site ecology (incl. possible dispersal mechanisms), hint that it is rare but established in the Mediterranean, and encourage further research into its distribution, ecophysiology, and taxonomy.

• Klíčová slova
• Invasive seagrass, Plasmodiophora, Plasmodiophorids, Seagrass disease, Seagrass symbionts, Tetramyxa,
• MeSH
• Cercozoa klasifikace   genetika   fyziologie   MeSH
• fylogeneze MeSH
• Hydrocharitaceae parazitologie   MeSH
• listy rostlin parazitologie   MeSH
• RNA protozoální analýza   MeSH
• RNA ribozomální 18S analýza   MeSH
• symbióza * MeSH
• zavlečené druhy MeSH
• Publikační typ
• časopisecké články MeSH
• Geografické názvy
• Itálie MeSH
• Středozemní moře MeSH
• Názvy látek
• RNA protozoální MeSH
• RNA ribozomální 18S MeSH

Understanding how an invasive plant can colonize a large range of environments is still a great challenge in freshwater ecology. For the first time, we assessed the relative importance of four factors on the phosphorus uptake and growth of an invasive macrophyte Elodea nuttallii (Planch.) St. John. This study provided data on its phenotypic plasticity, which is frequently suggested as an important mechanism but remains poorly investigated. The phosphorus uptake of two Elodea nuttallii subpopulations was experimentally studied under contrasting environmental conditions. Plants were sampled in the Rhine floodplain and in the Northern Vosges mountains, and then maintained in aquaria in hard (Rhine) or soft (Vosges) water. Under these conditions, we tested the influence of two trophic states (eutrophic state, 100 μg x l(-1) P-PO4(3-) and hypertrophic state, 300 μg x l(-1) P-PO4(3-)) on the P metabolism of plant subpopulations collected at three seasons (winter, spring and summer). Elodea nuttallii was able to absorb high levels of phosphorus through its shoots and enhance its phosphorus uptake, continually, after an increase of the resource availability (hypertrophic > eutrophic). The lowest efficiency in nutrient use was observed in winter, whereas the highest was recorded in spring, what revealed thus a storage strategy which can be beneficial to new shoots. This experiment provided evidence that generally, the water trophic state is the main factor governing P uptake, and the mineral status (softwater > hardwater) of the stream water is the second main factor. The phenological stage appeared to be a confounding factor to P level in water. Nonetheless, phenology played a role in P turnover in the plant. Finally, phenotypic plasticity allows both subpopulations to adapt to a changing environment.

• MeSH
• biologický transport MeSH
• fenotyp MeSH
• fosfor metabolismus   MeSH
• Hydrocharitaceae růst a vývoj   metabolismus   MeSH
• kinetika MeSH
• kvalita vody * MeSH
• vápník analýza   MeSH
• voda chemie   MeSH
• výhonky rostlin růst a vývoj   metabolismus   MeSH
• zavlečené druhy * MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• fosfor MeSH
• vápník MeSH
• voda MeSH