Effect of diet on the digestion of lignocellulosic compounds by Periplaneta americana: cellular and biochemical aspects.

Abstract

The cockroach Periplaneta americana is a very abundant insect in our country and has a great plasticity in the digestion of a wide variety of compounds, including plant lignocellulose compounds (mainly composed of cellulose, hemicellulose and lignin) . The aim of project is to study the cellular and biochemical influence of diet on digestion of lignocellulosic compounds in the cockroach P. americana. For this study we will feed exclusively the cockroaches with three different diets: diet (rich in protein), xylan (the most abundant hemicellulose in plants) and bagasse which is considered the main industrial source for biosynthesis of ethanol 2nd generation in our country. Initially we will analyze the intestinal enzymes activities of different groups by reactions using specific substrates for proteases and carbohydrases commonly described in the digestive tract of P. americana. Then we will determine the level of byproducts of the hydrolysis of polysaccharides, mainly formed by the oligomers (such as cellobiose, xylobiose , cellotriose , xylotriose, etc.) in the intestines of cockroaches with different diets. We will also measure the expression of several genes in insects (especially carbohydrases and proteases ) by " Real Time PCR " using " primers " generated from a transcriptome database of P. americana previously realized by Walter Terra´ Group . And finally we will make some immunolocalizations using antibodies and/or fluorescent substrates to find the specific endogenous enzymes involved in digestion of lignocellulosic compounds. The development of this project has strong multidisciplinary aspects that will require different techniques in biochemistry, molecular biology and cell biology. The project will be developed in collaboration between the professor Ednildo Machado of Instituto de Biofísica Carlos Chagas Filho , da Universidade Federal do Rio de Janeiro (IBCCF-UFRJ) e o professor Walter Terra (supervisor of project) do Departmento of Bioquímica do Instituto de Química da Universidade de São Paulo (DEBIQ-USP). The development of this project will be a great opportunity to start a collaboration between the groups in the study of several advanced aspects of insect physiology. In the future development of this project may generate scientific articles and specialized courses to graduated students at this strategic area for the two states (São Paulo and Rio de Janeiro). (AU)