Pesquisa de parasitas do gênero Trypanosoma em peixes provenientes de municípios de São Bento e Bacurituba da Baixada Maranhense

Abstract

Trypanosomes have been reported in several freshwater and freshwater fish species, with most species being described based on morphological characteristics. Fish parasitic trypanosomes are heteroxenes and are transmitted by hirudines. The present work had as objective to know a diversity of Trypanosoma in captured fishes, participation of municipalities of São Bento and Bacurituba in the Baixada Maranhense, through molecular parameters. Two collections were carried out, totaling 103 samples involving four species, Hoplias malabaricus (traíra), Hoplerythrinus unitaeniatus (jeju), Pygocentrus nattereri (red piranha) and Tilapia sp (tilapia). Blood was collected by cardiac puncture for the preparation of blood smears, which were fixed with methanol and stained by Giemsa for trypanosomes. The general frequency of trypanosomes was 51/103 (49, 51%). In order to identify as trypanosome species by molecular method, positive blood smears are used for DNA extraction. This was used for PCR amplification of two gene segments, such as bar code, parasite group, an 800-900pb fragment corresponding to the V7 and V8 variable region of the gene encoding a minor subunit of ribosomal RNA, a 600- 700 bp corresponding to the gene encoding glyceraldehyde 3- phosphate glycosidic dehydrogenase (gGAPDH). Of the 51 blood smear positive specimens, 37 were positive for both or the gene segments, which were cloned into plasmid pGEM-T. In this way clones of 17 samples were obtained, being 6 for the region V7V8 and 11 for gGAPDH. In the sequencing, 7 sequences of trypanosomes of the species Hoplias malabaricus (Traíra), Hoplerythrinus unitaeniatus (Jeju) and Pygocentrus nattereri (Red Piranha) were found. Thus, the fish were shown to have sequences of a single species and as identified as a species close to Trypanosoma clandestinus by BLAST analyzes. This is the first study with Trypanosoma in fish from Northeast Brazil and the results of the present study reinforce the need for molecular characterization using sensitive approaches to evaluate the repertoire of trypanosome species that infect these hosts.