The literature on the effects of phytohormone on algae is clouded with contradictory reports. Reports have been published which substantiate and deny the effects of phytohormones in enhancing the growth and developmental processes in algae. The overall aim of this study was to investigate the response, if any, of the phytohormones indole-3-acetic acid (IAA), gibberellic acid A3 (GA) and kinetin on the physiology of the green alga, Scenedesmus quadricauda. Results obtained for the uptake of 14^C-IAA an(j l4C-kinetin by Scenedesmus strongly support the presumption that the alga does not absorb the hormones. The retention of the phytohormones by the alga is due to adsorption, and is independent of hormone concentration. Most of the label was adsorbed by the outer pectic layers of the cell wall.

This report describes the effects of methylglyoxal on several green and blue-green algae, its correlation with photosynthesis, and a possible explanation of its metabolic role in the algae.

Three strains of the green alga Scenedesmus quadricauda were selected to be specifically resistant to the presence of high concentrations of inorganic Se. The strain SeIV was found to be resistant to high doses of selenite, the strain SeVI was resistant to selenate, and the strain Se(IV+VI) to the presence of both Se compounds. It has been shown that both the dose and chemical form of Se are the critical factors in the cellular response. In this PhD. thesis are results from experiments with the resistant strains (activity of thioredoxin reductase, content of selenium and selenomethionine, effect of sulphur deficiency).

The purpose of this study was to investigate the metabolic pathways of methylglyoxal in S. quadricauda.

This thesis studies effect of cultivation conditions on the production of secondary me-tabolites in the green microalgae Scenedesmus quadricauda. During the experiment was studied influence of pH, UVC radiation, light intensity and various temperature conditions on the amount of biologically active compounds (polyphenols, flavonoids, antioxidants). Metabolites were determined using biochemical analytical methods. The total content of polyphenols was determined using the Folin-Ciocalteu method, which is based on chemical reaction of phenols with Folin-Ciocalteu reagent. The total con-tent of flavonoids was determined spectrophotometrically using AlCl3.6H2O with the addition of NaNO2 and 1 M NaOH. The total antioxidant capacity (TAC) was deter-mined using phosphomolybdenun antioxidant assay. Antioxidant activity was stimu-lated by UVC radiation. The highest value being recorded when samples were exposed to UVC for 5 minutes. Light intensity and the temperature changes did not have significant effect on antioxidant activity of studied samples. There was an increase in TAC in samples cultured in acid pH medium (4 and 5). The content of polyphenolic and flavonoid compounds with high light intensity (3500, 4000 lx) and high tempera-tures (35 °C, 40 °C) decreased. Conversely, changes in pH and UV-C stimulate biosyn-thesis of both polyphenols and flavonoids. The greatest increase of these compounds was observed in the medium with pH = 4 and the time of exposure to UV-C for 5 minutes a day.

Cell division of ggeneflesmus quadricauda (Turp.) Breb. (Scenedesmaceae) is enhanced by methylglyoxal, a general inhibitor of cell division, at threshold concentration in conjunction with treatment timing related to growth stage of batch cultures. At 0.5 mM methylglyoxal concentration, cell division was significantly enhanced in algae treated in the logarithmic phase. Specific growth rates of methylglyoxal-treated cultures were rapidly increased at the beginning of logarithmic phase. Cultures inoculated with high cell numbers were less sensitive, but still showed high specific growth rates in logarithmic phase. Cell division in cultures which had low cell numbers was inhibited by 0.5 mM methylglyoxal treatment. Both specific activity of Glyoxalase I and the ratio of Glyoxalase I to Glyoxalase II of methylgloxal-treated cultures were higher than those of controls (1.3 and 2.1- fold, respectively). Pyruvate concentration in treated cultures was increased after methylglyoxal treatment.

The effect of FdUrd, zeocin, caffeine and their combination on the cell cycle of green algae Chlamydomonas reinhardtii and Scenedesmus quadricauda and response of these model organisms to DNA damage were studied. Both, FdUrd and zeocin, caused DNA damage that led to cell cycle arrest in these algae. In contrast, caffeine partially abolished G2 phase block imposed by zeocin. Protein levels of three crucial cell cycle regulators - CdkA, CdkB and Wee1 kinases were measured to identify mechanisms controlling reaction to DNA damage.

The theoretical overview summarize the characteristics of algae and their primary and secondary metabolism. It also deals with inhibitors of ascorbic acid, glutathione and polyphenolic compounds synthesis. The practical part studies the influence of selected inhibitors (BSO, Lyc, AIP) and CdCl2 on the secondary metabolites production and biomass growth in freshwater microalgae Scenedesmus quadricauda. The content of secondary metabolites (eg. caffeic acid, chlorogenic acid, salicylic acid, cinnamic acid, p-coumaric acid) was detected by HPLC-MS. Furthermore, the total antioxidant capacity, the total polyphenol content and the total flavonoid content was determined spectrophotometrically. All the inhibitors used, reduced S. quadricauda growth in comparison with control samples. The most pronounced inhibitory effect was observed in the samples treated with Lyc + Cd after 7 days of experiment. All the treated samples responded to the stress factors by altering metabolic pathways and inhibiting growth. As a result, there were changes in the composition and the amount of selected secondary metabolites versus the control samples. At the same time, in most cases, the biosynthesis of polyphenolic and flavonoid substances has been stimulated. The oxidative reduction equilibrium and the induction of oxidative stress were probably impaired.

Made available in DSpace on 2016-08-10T10:31:07Z (GMT). No. of bitstreams: 1 JOSE BENEDITO GIRARDELLO VENDRUSCOLO.pdf: 1476146 bytes, checksum: 5292fae7b7d577ba381792d84556d542 (MD5) Previous issue date: 2009-09-21 / O alimento originado do plâncton que chega ao peixe é o zooplancton e sua preferência alimentar na rede trófica são as microalgas, cuja autotrofia permite a riqueza de todos os sistemas aquáticos do mundo. Na produção aquícola os estudos de organismos como as microalgas, que possam permitir a produção sustentável na atividade, são necessários e relevantes. A microalga Scenedesmus quadricauda tem características especiais tais como digestibilidade, preferência de consumo, facilidade de cultivo. Objetivando a maximização da produção autotrófica e redução de custos no cultivo da microalga Scenedesmus quadricauda, dejetos biodigeridos de suínos e aves foram testados juntamente com meio de cultura Chu, tradicionalmente utilizado para essa finalidade. Esses produtos são disponíveis e de baixo custo na região do Sudoeste de Goiás, graças ao incremento regional da atividade de suinocultura e avicultura e ao seu potencial de crescimento nos últimos anos. Assim, o presente trabalho foi desenvolvido no Laboratório de Aquicultura do Departamento de Zootecnia da Universidade Católica de Goiás, atendendo às condições ambientais necessárias para cultivo da microalga Scnedesmus quadricauda em meio de cultivo tradicional. Durante quatorze dias foram avaliadas as quatro repetições dos três tratamentos: meios de cultura Chu, biodigerido de aves e biodigerido de suínos. Concluiu-se que o meio de cultivo Chu tradicional pode ser substituído pelos meios de cultivo biodigerido de suínos e aves sem perda na produção de células da microalga Scenedesmus quadricauda, uma vez que a comparação entre eles não apresentou diferença significativa ao nível de 5% de probabilidade. Os picos de crescimento que representam produtividade para os três meios de cultura diferiram entre si com superioridade para biodigerido de aves e suínos em relação ao meio Chu.

The aim of this work is to evaluate the effect of caprolactam on the process of photosynthesis in model representatives of green algae (Scenedesmus quadricauda) through the dynamics of the release of oxygen into the solution of medium.