Speakers - Dulce H. Ferreira de Souza

Type of the Presentation: (Short lecture)




Dulce H. Ferreira de Souza.

São Carlos Federal University, Chemistry Departmente,  Brazil


Atta sexdens rubropilosa is an important leaf-cutting ant species considered as a pest in agricultural crop or reforestation areas. The excessive use of pesticide to control these ants cause environmental problems and poisoning of other animals. Silencing of a specific gene can be an alternative and the studies starts with the analysis of expression level and function of a gene. The objective of this work is to verify the expression level of chitin synthase in A. sexdens rubropilosa and to evaluate its function through gene silencing. Two groups were selected to evaluate the genes profile expression, developmental stages (larva, pupa and worker) and tissues (head, thorax, abdomen and worker without abdomen) in biological triplicate. The total RNA was extracted, quantified and its integrity was analysed. The samples were treated with DNase and used in a reaction to obtain cDNA. For RT-qPCR analysis were synthetized primers to the target gene chitin synthase (CHS) and for the reference genes rpl18 and ef1-alpha for the different developmental stages and rpl18 and ef1-beta for the different tissues. The parameters to reach an accurate result for expression analysis was followed. The raw values of Ct obtained were used with to determine the relative expression level of the target by 2-ΔΔCt method. The statistical analysis was done using the GraphPad Prism 5. The relative expression of CHS was higher in pupa, followed by larva and worker without gaster exhibiting the lowest level.  To evaluate the interference of CHS in the development of leaf cutting ants, the RNA interference (RNAi) technique was used. For this, double-stranded RNA (dsRNA) was injected into larvae and, at the moment, RNA are being extracted every 24 hours to check the expression level of the gene. Also being carried out experiments of observation of morphological modification of the larvae injected with the  dsRNA.

The expression profile of the enzymes are associated with their function and can guide development of specific insecticides that act on tissue/stages were the enzymes are been high expressed.