algae
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svazky : ilustrace, mapy ; 27 cm
- MeSH
- bakteriologie MeSH
- botanika MeSH
- environmentální zdraví MeSH
- mikrořasy * MeSH
- sinice MeSH
- škodlivý vodní květ MeSH
- toxikologie MeSH
- Publikační typ
- periodika MeSH
- Konspekt
- Mikrobiologie
- NLK Obory
- bakteriologie
- toxikologie
Differences in the level of cold acclimation and cryoprotection estimated as ice nucleation activity in snow algae (Chlamydomonas cf. nivalis and Chloromonas nivalis), lichen symbiotic algae (Trebouxia asymmetrica, Trebouxia erici and Trebouxia glomerata), and a mesophilic strain (Chlamydomonas reinhardti) were evaluated. Ice nucleation activity was measured using the freezing droplet method. Measurements were performed using suspensions of cells of A750 (absorbance at 750 nm) ~ 1, 0.1, 0.01 and 0.001 dilutions for each strain. The algae had lower ice nucleation activity, with the exception of Chloromonas nivalis contaminated by bacteria. The supercooling points of the snow algae were higher than those of lichen photobionts. The supercooling points of both, mesophilic and snow Chlamydomonas strains were similar. The lower freezing temperatures of the lichen algae may reflect either the more extreme and more variable environmental conditions of the original localities or the different cellular structure of the strains examined.
BACKGROUND AND AIMS: The metabolism of cytokinins (CKs) and auxins in vascular plants is relatively well understood, but data concerning their metabolic pathways in non-vascular plants are still rather rare. With the aim of filling this gap, 20 representatives of taxonomically major lineages of cyanobacteria and algae from Cyanophyceae, Xanthophyceae, Eustigmatophyceae, Porphyridiophyceae, Chlorophyceae, Ulvophyceae, Trebouxiophyceae, Zygnematophyceae and Klebsormidiophyceae were analysed for endogenous profiles of CKs and auxins and some of them were used for studies of the metabolic fate of exogenously applied radiolabelled CK, [(3)H]trans-zeatin (transZ) and auxin ([(3)H]indole-3-acetic acid (IAA)), and the dynamics of endogenous CK and auxin pools during algal growth and cell division. METHODS: Quantification of phytohormone levels was performed by high-performance or ultrahigh-performance liquid chromatography-electrospray tandem mass spectrometry (HPLC-MS/MS, UHPLC-MS/MS). The dynamics of exogenously applied [(3)H]transZ and [(3)H]IAA in cell cultures were monitored by HPLC with on-line radioactivity detection. KEY RESULTS: The comprehensive screen of selected cyanobacteria and algae for endogenous CKs revealed a predominance of bioactive and phosphate CK forms while O- and N-glucosides evidently did not contribute greatly to the total CK pool. The abundance of cis-zeatin-type CKs and occurrence of CK 2-methylthio derivatives pointed to the tRNA pathway as a substantial source of CKs. The importance of the tRNA biosynthetic pathway was proved by the detection of tRNA-bound CKs during the course of Scenedesmus obliquus growth. Among auxins, free IAA and its oxidation catabolite 2-oxindole-3-acetic acid represented the prevailing endogenous forms. After treatment with [(3)H]IAA, IAA-aspartate and indole-3-acetyl-1-glucosyl ester were detected as major auxin metabolites. Moreover, different dynamics of endogenous CKs and auxin profiles during S. obliquus culture clearly demonstrated diverse roles of both phytohormones in algal growth and cell division. CONCLUSIONS: Our data suggest the existence and functioning of a complex network of metabolic pathways and activity control of CKs and auxins in cyanobacteria and algae that apparently differ from those in vascular plants.
- MeSH
- Chlorophyta chemie metabolismus fyziologie MeSH
- cytokininy analýza metabolismus MeSH
- fylogeneze MeSH
- hmotnostní spektrometrie s elektrosprejovou ionizací metody MeSH
- homeostáza fyziologie MeSH
- kyseliny indoloctové analýza metabolismus MeSH
- regulátory růstu rostlin analýza metabolismus MeSH
- sinice chemie metabolismus fyziologie MeSH
- Streptophyta chemie metabolismus fyziologie MeSH
- tandemová hmotnostní spektrometrie metody MeSH
- vysokoúčinná kapalinová chromatografie metody MeSH
- Publikační typ
- časopisecké články MeSH
Green algae dividing by multiple fission comprise unrelated genera but are connected by one common feature: under optimal growth conditions, they can divide into more than two daughter cells. The number of daughter cells, also known as the division number, is relatively stable for most species and usually ranges from 4 to 16. The number of daughter cells is dictated by growth rate and is modulated by light and temperature. Green algae dividing by multiple fission can thus be used to study coordination of growth and progression of the cell cycle. Algal cultures can be synchronized naturally by alternating light/dark periods so that growth occurs in the light and DNA replication(s) and nuclear and cellular division(s) occur in the dark; synchrony in such cultures is almost 100% and can be maintained indefinitely. Moreover, the pattern of cell-cycle progression can be easily altered by differing growth conditions, allowing for detailed studies of coordination between individual cell-cycle events. Since the 1950s, green algae dividing by multiple fission have been studied as a unique model for cell-cycle regulation. Future sequencing of algal genomes will provide additional, high precision tools for physiological, taxonomic, structural, and molecular studies in these organisms.
Most cells divide into two daughter cells; however, some green algae can have different division patterns in which a single mother cell can sometimes give rise to up to thousands of daughter cells. Although such cell cycle patterns can be very complex, they are governed by the same general concepts as the most common binary fission. Moreover, cell cycle progression appears to be connected with size, since cells need to ensure that their size after division will not drop below the limit required for survival. Although the exact mechanism that lets cells measure cell size remains largely unknown, there have been several prominent hypotheses that try to explain it.
Natural products have been used as treatment of various diseases from time immemorial and even nowadays majority of commercially available drugs on the market are derived from natural compounds. Ocean provides a home to a number of marine organisms including algae and shelter endless sources of new natural biologically active compounds. Marine algae had to cope with harsh stress conditions, which gave them outstanding variability and made them one of the major sources of compounds with unique chemical features and with exceptional biological activity. Amongst these compounds belong sulphated polysaccharides, special pigments, halogenated compounds, mycosporine-like amino acids and many other compounds beneficial to human health. Despite the tremendous amount of publications declaring impressive biological activities of algal compounds, so far only one of them was approved as antiviral drug. Nevertheless, with the advancements in technology, soon other will follow.
The consumption of polyamides produced from caprolactam is increasing continuously, and for that reason the danger of environmental contamination by this lactam is also rising. This study's aim was to evaluate the influence of caprolactam on the growth and oxygen production of the green alga Desmodesmus quadricauda and on caprolactam uptake by this alga. The presence of caprolactam in water was observed to cause the algae significantly to increase its oxygen production. Caprolactam concentration of 5,000 mg/L stopped algae growth after 6 days and influenced coenobia structure (seen as disappearance of pyrenoids, deformation of cells) but did not decrease the number of cells in the coenobia. Caprolactam uptake is probably passive but relatively rapid. Maximum concentration in the algae was reached after 18-24 h.
Polarization microscopy, possibly together with some contrast techniques (dark field and color phase contrast), was used to study the periphyton (microbiome) growing on filamentous green algae. The material containing filamentous algae with periphyton on the surface was collected in the villages of Sýkořice and Zbečno (Křivoklátsko Protected Landscape Area). The objects were studied in a LOMO MIN-8 St. Petersburg polarizing microscope and a Carl Zeiss Jena NfpK laboratory microscope equipped with an In Ph 160 basic body with variable dark field or color phase contrast and a Nikon D70 DSLR digital camera. Cells of filamentous algae of the genera Cladophora, Vaucheria, and Oedogonium were studied and the periphyton attached to them formed by cyanobacteria of the genera Chamaesiphon and Pleurocapsa and algae of the genera Characium, including diatoms of the genera Eunotia and Synedra. In all cases, the cell walls of the host algae showed a very strong birefringence. In contrast, the walls of cyanobacteria of the genera Chamaesiphon and Pleurocapsa were characterized by a much weaker birefringence (Pleurocapsa somewhat thicker), and the diatom frustules of the genera Eunotia and Synedra were almost without a birefringence. Strongly birefringent granules were found in the cytoplasm of the green alga of the genus Characium, which forms periphyton on the filamentous green algae of the genus Vaucheria. The periphyton on the filamentous alga of the genus Oedogonium, formed by cyanobacteria of the genus Pleurocapsa and diatoms of the genera Eunotia and Synedra, deposited in a massive layer of mucus containing birefringent crystals, showed a particularly strong birefringence. At the end of the vegetation of filamentous algae, their parts and remnants of periphyton (diatom frustules and crystals) became part of the detritus at the bottom of the culture vessel. The use of polarization microscopy in the study of filamentous algae with periphyton on the surface allows us not only to determine the birefringence of the observed structures, but also to partially deduce their chemical composition, or regular arrangement of particles, so-called shape birefringence.
