Caracaterização morfológica e molecular de um myxozoário em Brachyplatystoma vaillantii (Valenciennes, 1840) capturada no litoral amazônico

Abstract

This study analyzed myxozoans, microscopic cnidarian parasites highly adapted to parasitic relationships with aquatic organisms. With more than 2400 species cataloged in marine and freshwater environments, myxozoans establish a significant co-evolutionary relationship with their hosts. In this study, specimens of Brachyplatystoma vaillantii (Valenciennes, 1840), popularly known in the northern region of Brazil as Piramutaba, were analyzed, being a freshwater catfish widely distributed in South America. For the study, morphological and phylogenetic analyzes were conducted (18S rDNA) to characterize the myxozoan parasites found in piramutaba, since species of the genus Ceratomyxa have tissue tropism for the gallbladder of marine fish. The present study seeks to identify the morphological and phylogenetic aspects of the diversity of microparasites, using Light Microscopy (ML) and Molecular Biology (BM) techniques. 50 specimens of B. vaillantii were collected with the help of artisanal fishermen in Colares/PA, using fishing instruments. The fish were preserved in isothermal vats with ice and transported to the Carlos Azevedo Research Laboratory – UFRA, on the UFRA/Belém campus, for processing and observation using ML and BM techniques. Structures of plasmodia and spores with morphological characteristics of the genus Ceratomyxa were identified in the gallbladder. The plasmodia showed slow movements, with different sizes, while the spores had a furcated morphology, with the following morphometry: 19.7 μm ± 1.2 μm in length, width 3.97 μm ± 0.99 μm; polar capsule: 1.1 μm ± 0.3 μm long, 1.04 ± 0.2 μm wide. The analysis showed a prevalence of 60% of sequences from the genus Ceratomyxa in the samples collected. The results obtained indicate the presence of parasites in the fish studied, highlighting the importance of morphological investigation of microparasites in fish. Understanding parasite ecology is crucial to implementing effective disease control and prevention measures. Therefore, this study aims to fill knowledge gaps in the area of fish parasitology, contributing to scientific advancement and the development of effective measures for the management and conservation of fishing resources in the region.