• MeSH
• anestetika lokální antagonisté a inhibitory   MeSH
• fotosyntéza účinky léků   MeSH

• MeSH
• Eukaryota MeSH
• mikrobiologické techniky metody   MeSH
• znečištění vody MeSH

• 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

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.

• MeSH
• buněčný cyklus * MeSH
• Chlorophyta cytologie   genetika   MeSH
• replikace DNA MeSH
• světlo MeSH
• teplota MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• přehledy MeSH

• MeSH
• Chlorophyta chemie   MeSH
• intoxikace vodou MeSH
• jedy farmakologie   MeSH
• rizikové faktory analýza   MeSH
• voda MeSH

• Konspekt
• Lékařské vědy. Lékařství
• NLK Obory
• environmentální vědy
• toxikologie
• patologie
• fyziologie
• NLK Publikační typ
• publikace WHO

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.

• MeSH
• buněčné dělení * MeSH
• buněčný cyklus * MeSH
• Chlorophyta cytologie   růst a vývoj   metabolismus   MeSH
• velikost buňky MeSH
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH

Here is presented some of the first information on interactions of compounds produced by cyanobacteria and green algae with estrogen receptor signaling. Estrogenic potency of aqueous extracts and exudates (culture spent media with extracellular products) of seven species of cyanobacteria (10 different laboratory strains) and two algal species were assessed by use of in vitro trans-activation assays. Compounds produced by cyanobacteria and algae, and in particular those excreted from the cells, were estrogenic. Most exudates were estrogenic with potencies expressed at 50% of the maximum response under control of the estrogen receptor ranging from 0.2 to 7.2 ng 17β-estradiol (E(2)) equivalents (EEQ)/L. The greatest estrogenic potency was observed for exudates of Microcystis aerigunosa, a common species that forms water blooms. Aqueous extracts of both green algae, but only one species of cyanobacteria (Aphanizomenon gracile) elicited significant estrogenicity with EEQ ranging from 15 to 280 ng 17β-estradiol (E(2))/g dry weight. Scenedesmus quadricauda exudates and extracts of Aphanizomenon flos-aquae were antagonistic to the ER when coexposed to E(2). The EEQ potency was not correlated with concentrations of cyanotoxins, such as microcystin and cylindrospermopsin, which suggests that the EEQ was comprised of other compounds. The study demonstrates some differences between the estrogenic potency of aqueous extracts prepared from the same species, but of different origin, while the effects of exudates were comparable within species. The observed estrogenic potencies are important namely in relation to the possible mass expansion of cyanobacteria and release of the active compounds into surrounding water.

• MeSH
• Aphanizomenon metabolismus   MeSH
• biotest MeSH
• chemické látky znečišťující vodu metabolismus   farmakologie   MeSH
• Chlorophyta metabolismus   MeSH
• endokrinní disruptory metabolismus   farmakologie   MeSH
• estradiol metabolismus   farmakologie   MeSH
• estrogeny metabolismus   farmakologie   MeSH
• eutrofizace MeSH
• exsudáty a transsudáty chemie   MeSH
• mezibuněčná komunikace fyziologie   MeSH
• Microcystis účinky léků   MeSH
• receptory pro estrogeny metabolismus   MeSH
• sinice metabolismus   MeSH
• vztah mezi dávkou a účinkem léčiva MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Lyngbya major (a wall alga), survived throughout year, maximally to >80 % at atmospheric temperature (AT) of 17-36 degrees C and relative humidity (RH) 60-100 % in rainy and spring seasons, but the survival was 43-64 % in winter when AT decreased to 5 degrees C and RH was 65-98 %, and 15-23 % in summer when AT reached 48 degrees C and RH was 23-60 %. All soil algae (Lyngbya birgei, Aphanothece pallida, Gloeocapsa atrata, Oscillatoria subbrevis, O. animalis) survived >90 % in rainy season when soil moisture content (SMC) was 89-100 %. Lowering of SMC to a minimum of 55 % in spring and 39 % in winter led L. birgei, O. subbrevis and O. animalis to survive from 75, 66, and 65 %, respectively, in spring and 12, 14, and 20 % in winter, and A. pallida and G. atrata not at all in both seasons. All soil algae did not survive in summer when SMC was 12-30 %. Myxosarcina burmensis survived only in rainy and spring seasons when pond water temperature (PWT) was 19-25 degrees C and 18-26 degrees C, respectively, and not in winter and summer when PWT was 2-14 degrees C and 25-36 degrees C, respectively. L. major and A. pallida survived almost equally well under both submerged and air-exposed conditions for 15 d but less if submerged for more time than air-exposed on moist soil surface, while L. birgei, G. atrata, O. subbrevis, and O. animalis survived submergence in liquid medium better and longer than air-exposure on moist soil surface. Pond alga M. burmensis survived submergence better than air-exposure, true to its aquatic habitat. All algae survived less and died without forming any resistant cells when exposed to physical and physiological water stress (imposed by growing them on highly agarized media or in salinized liquid media), light stress (at 0, 2 and 10 micromol m(-2) s(-1) light intensity) or following UV shock (0.96-3.84 kJ/m(2)). A. pallida and G. atrata cells did not divide on 8 % agarized solid media, in > or =0.3 mol/L salinized liquid media, and in darkness. The presence of sheath over L. major and L. birgei filament cells and mucilage cover over A. pallida and G. atrata cells protect them against physical desiccation to some extent but not against UV shock.

• MeSH
• ekosystém MeSH
• fyziologický stres MeSH
• mikrobiální viabilita účinky záření   MeSH
• půda MeSH
• půdní mikrobiologie MeSH
• roční období MeSH
• sinice fyziologie   účinky záření   MeSH
• teplota MeSH
• ultrafialové záření MeSH
• vlhkost MeSH

Fourteen blue-green and green algae survived for widely different time periods ranging between 22-102 d in control culture medium. Irrespective of their long or short survival period in control cultures, their pro- or eukaryotic nature, their different morphological types or natural habitats, they all survived for a short time period ranging between 3-8 d in sewage water, 5-10 d in fertilizer factory effluent, (1/4)-2 d in brassica oil, (1/2)-2 d in phenol, 1-3 d in toluene, and 1-4 d in benzene (showing the relative toxicity of different chemicals to different algae, and the antialgal nature of brassica oil). Dilution decreased the toxicity of these agents very little, indicating that they all were very toxic to algae. None of the agent induced the formation of any reproductive or dormant cells. Sewage water, fertilizer factory effluent, brassica oil and/or benzene favored the formation of necridia cells in Phormidium bohneri, P. foveolarum, Microcoleus chthonoplastes, Lyngbya birgei, and L. major filaments. Scenedesmus quadricauda shed off all spines earlier, Hormidium flaccidum fragmented less or not at all, Scytonema millei formed no false branch and heterocyst, Aphanothece pallida and Gloeocapsa atrata cells did not divide, Cosmarium granatum cells did not form any zygospore and Oedogonium sp. not any oogonia-like cells under all or most of treatments with 25-100 % sewage water, 1-100 % fertilizer factory effluent, 1-100 % brassica oil, 25-100 % phenol, toluene and benzene.

• MeSH
• benzen farmakologie   MeSH
• chemické látky znečišťující vodu farmakologie   MeSH
• Chlorophyta fyziologie   účinky léků   MeSH
• fenol farmakologie   MeSH
• odpadní vody analýza   MeSH
• organické látky farmakologie   MeSH
• průmyslový odpad analýza   MeSH
• rozmnožování účinky léků   MeSH
• spory fyziologie   účinky léků   MeSH
• toluen farmakologie   MeSH

A synchronous population of cells is one of the prerequisites for studying cell cycle processes such as DNA replication, nuclear and cellular division. Green algae dividing by multiple fission represent a unique single cell system enabling the preparation of highly synchronous cultures by application of a light-dark regime similar to what they experience in nature. This chapter provides detailed protocols for synchronization of different algal species by alternating light-dark cycles; all critical points are discussed extensively. Moreover, detailed information on basic analysis of cell cycle progression in such cultures is presented, including analyses of nuclear, cellular, and chloroplast divisions. Modifications of basic protocols that enable changes in cell cycle progression are also suggested so that nuclear or chloroplast divisions can be followed separately.

• MeSH
• barvení a značení metody   MeSH
• buněčné dělení MeSH
• buněčné kultury metody   MeSH
• buněčný cyklus MeSH
• Chlamydomonas reinhardtii cytologie   genetika   růst a vývoj   MeSH
• Chlorophyta cytologie   genetika   růst a vývoj   MeSH
• chloroplasty genetika   MeSH
• DNA rostlinná genetika   MeSH
• fotoperioda * MeSH
• frakcionace buněk metody   MeSH
• replikace DNA MeSH
• světlo MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH