Dados da Tese de Doutorado

Author: Ricardo Rogers Paranhos
 
Title: Physiological, chemical and molecular efects of high concentrations of CO2 in Cylindrospermopsis raciborskii (Cyanobacteria)
 
Year: 2017                                         Full text (in Portuguese)
 
Abstract:
CO2 is a gas that has received great attention in recent years, since it is the main cause of the greenhouse effect and its high increase is related to industrialization processes. It is estimated that by the end of this century the current concentrations (400 ppm) will triplicate, causing even more serious impacts on the climate and consequently harming the environment and its organisms. Cyanobacteria is one of the oldest group of organisms (3.8 billion years old) and therefore have evolved in face of the great number of environmental changes that happened so far. One of these events was the increase of CO2 concentrations in the Paleocene period reaching levels 10 fold higher than current (4000 ppm). Though, the present study evaluated the physiological, chemical (saxitoxin and cyanopeptides) and transcriptomic responses of toxin producing and non-producing Cylindrospermopsis raciborskii strains, against concentrations of 400 and 4,000 ppm of CO2, in order to understand this harmfull algal bloom former would behave. Saxitoxin producing lineages (CYRF and T3), in general, had a stable growth and toxin production. However, when analyzing the growth rates of non-producing strains (CYLP and NPCS-1) and their transcriptomes, it was observed that the groups exposed to high CO2 had lower rates of growth and increased RNA regulation. The comparative analysis of the extracts of cyanopeptides allowed to observe that CYLP and T3 varied the production of those molecules of greater molecular weight under higher CO2. It was observed that the main variations occurred among strains, varying physiology and metabolism in different ways, drawing attention to the fact that different strains respond differently to stress. The results also call attention to the need to improve knowledge on cyanopeptides and their ecological roles and also the need to deepen expertise on transcriptomic techniques applied to cyanobacteria.