Gracilariopsis tenuifrons (Gracilariales-Rhodophyta) response to irradiance stimuli in vitro

Author(s)

Daniele Ramalho Serra

• Document type: Master's Dissertation
• Press: São Paulo.
• Institution: Universidade de São Paulo (USP). Instituto de Biociências (IBIOC/SB)
• Defense date: 2013-04-16

Examining board members

Fanly Fungyi Chow Ho; Estela Maria Plastino

• Advisor: Fanly Fungyi Chow Ho

Abstract

Algae are organisms adapted to constant and abrupt abiotic changes characteristic of marine environment, that cause stress and are responsible for physiological alterations able to damage basic biological functions. The intense PAR can produces oxidative stress on seaweed, resulting in oxidation of pigments and proteins, affecting the growth and driven to alterations that can conduce to cell death. This oxidative stress leads ROS and NO accumulation that directly or indirectly prejudice the metabolic fitness of the organism. To mitigate and control the deleterious effect of these radicals, the organism has diverse antioxidative defenses, as to increase phenolic compounds, degradation of photosynthetic pigments, providing polysaccharides and wall thickness and activation of enzymatic and non-enzymatic antioxidative systems. Thus, aiming to understand the physiological responses of Gracilariopsis tenuifrons to intense irradiance were evaluated levels of photosynthetic pigments, proteins, tissular carbon, hydrogen and nitrogen, growth rate, amount of total phenolic compounds, total antioxidant activity and lipid peroxidation, and ROS and NO production. Therefore, apices of 3 cm from the red seaweed Gp. Tenuifrons were exposed to 60 μmol photons.m-2.s-1 and 600 μmol photons.m-2.s-1 for one week and sampling during the day and night. The excess of irradiance promoted oxidative stress responses, observing significant reduction of pigments, soluble proteins and tissular nitrogen, and elevation of tissular carbon and hydrogen, phenolic compounds, total antioxidant activity and quantity of NO. Gracilariopsis tenuifrons showed effective activation of diverse antioxidant systems stimulated by high light. This antioxidant induction should be better explored in applications for food, medical, pharmaceutical and cosmetic industries. Moreover this study shows innovative results related to NO production under stress condition and methodological protocols will be of great help for physiological approaches in the Laboratory of Marine Algae \"Édison José de Paula\" and for other national and international research groups (AU)

• FAPESP's process: 10/06732-5 - Gracilariopsis tenuifrons response to in vitro irradiation stimuli.
• Grantee: Daniele Ramalho Serra
• Support Opportunities: Scholarships in Brazil - Master