Analysis of the rapamycin-sensitive signaling pathway role in gene expression and cell multiplication of Chlamydomonas reinhardtii

Author(s)

Gustavo Pereira de Almeida

• Document type: Master's Dissertation
• Press: Campinas, SP.
• Institution: Universidade Estadual de Campinas (UNICAMP). Instituto de Biologia
• Defense date: 2012-08-28

Examining board members

Gonçalo Amarante Guimarães Pereira; Jörg Kobarg; Tie Koide

• Advisor: Gonçalo Amarante Guimarães Pereira

Abstract

The energy production through renewable sources is an actual demand for achieving a sustainable economy. In this context, photosynthesizing organisms come to light as important tools for the production of energy-rich carbonic compounds, especially the microalgae, in which these compounds can reach up to 80% of the dry weight. However, an unfavorable factor for its utilization is the low yield of biomass production. The species Chlamydomonas reinhardtii, for instance, is capable of achieving only some duplication after 24 hours. The pathways that control cell growth are therefore promising targets for genetic modification. Among them, the rapamycin-sensitive signaling pathway emerges as a central controller. With the aim of better understanding how this control is fulfilled by the means of global gene expression, the high throughput RNA sequencing technology was used. With it, the synchronized cultures transcriptome under the inhibition of this pathway and in the control condition, of eight points during a cellular cycle of 24 hours, were obtained. The metabolism and the cell cycle control by the TOR pathway was the main focus of the analysis. It was found that the inhibition of this pathway is capable to partially draw the metabolism towards TAG production to the detriment of producing more complex chains as proteins. This directing was considered partial due to the concomitant occurrence of catabolic reactions. Other data suggested that the TOR pathway, apart from the metabolism regulation in a general way and regulation of many other cellular functions, also influence the cell cycle progression and its inhibition retards the development of cell phases. Several transcription regulators involved in development, growth and cell cycle regulation were found out to be differentially expressed and are likely to constitute key genes in growth control. They represent potential targets for genetic modification aiming the optimization of growth rate in the first step of the production system. In the search for alternatives to the current process of inducing carbon chain accumulation, the effects of the combination between rapamycin and TOR pathway represent an interesting approach for future research intending to turn the utilization of microalgae as an energy source into a feasible option. This study enabled a better understanding of the role of the TOR pathway in growth and cell cycle progression of C. reinhardtii at the level of gene expression (AU)

• FAPESP's process: 09/13066-4 - Role Analysis of the Rapamycin Sensitive Sinaling Pathway on the genic expression and celular multiplication of Chlamydomonas reinhardtii
• Grantee: Gustavo Pereira de Almeida
• Support Opportunities: Scholarships in Brazil - Master