The tick Rhipicephalus microplus is the main cattle ectoparasite in the southern hemisphere and important vector of Anaplasma marginale. This bacteria is responsible for anaplasmosis, a disease that affects the herds and induce serious damage to the economic livestock farming in Brazil. The A. marginale is a mandatory intracellular bacteria which presents a reduced genome, which increases their dependence for the cell host in metabolic terms, as carbon sources of supply, amino acids, lipids and micronutrients (Brayton et al., 2005). Literature data indicates that important sources of carbon, such as glucose, glycogen and triglycerides, can not be directly metabolized by A. marginale, since this bacteria dig not show in their genoma the encoding genes of the enzymes responsible for the hydrolysis of these compounds, depending on other possible carbon sources of the host cell, such as amino acids. Moreover, few encoding genes of enzymes involved in the biosynthesis of amino acids were identified and only the biosynthetic pathways of the amino acids proline, glutamine and glycine are complete (Brayton et al., 2005). Corroborating with the hypothesis in which the bacteria depends on the host cell for its survival, data obtained in our laboratory indicated that embryonic cells of the tick (BME26 lineage) present an increase in the levels of several transcripts related to glycolysis, the citric acid cycle and the metabolism of amino acids (aspartate and glutamate biosynthesis) when infected with A. marginale. Furthermore, infected A, marginale line BME26 differential proteome data showed that several enzymes of the citric acid cycle, as well as the synthesis pathway components of some amino acids, had its levels increased. These results may indicate an increased energy metabolism of the cell with an increased carbon sources consumption for the production of relevant intermediates for the bacteria. Until now there are no studies on energy metabolism of the interaction tick- A. marginale. Therefore, identifying the components of the metabolic pathways of cells that are explored for the survival and multiplication of A. marginale is relevant to control anaplasmosis, since a failure in the acquisition of these could limit the capacity of the bacteria to colonize the host.
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