Análise morfológica, ultraestrutural e molecular de mixozoários (Cnidaria) parasitos de Pimelodina flavipinnis (Siluriformes: Pimelodidae) da bacia Amazônica
Data
2021-10-27
Autores
Araújo, Bruno de Lima 
Orientadores
Naldoni, Juliana
Tipo
Dissertação de mestrado
Título da Revista
ISSN da Revista
Título de Volume
Resumo
A bacia Amazônica é a maior bacia hidrográfica da América do Sul. Composta por uma rica ictiofauna, um de seus principais grupos de peixes são os da família Pimelodidae, sendo a espécie Pimelodina flavipinnis comumente encontrada. A ictiofauna amazônica é acometida por diversos patógenos, como aqueles da classe Myxozoa, cnidários endoparasitos que vêm recebendo grande destaque científico nos últimos anos. Através deste estudo, foi registrado, pela primeira vez, uma espécie de Ceratomyxa infectando a vesícula biliar de Pimelodina flavipinnis. Foram examinados doze exemplares desse peixe coletados no rio Solimões, sendo que sete (58%) estavam infectados. A medição dos mixosporos demonstrou média de 4,6 ± 0,5 (3,4 – 5,5) μm de comprimento, 31,2 ± 2,3 (26,2 – 36,3) μm de espessura e 162 ± 10,4 (143 – 178) ° de ângulo posterior. As cápsulas polares apresentaram 1,8 ± 0,3 (1,0 – 2,5) μm de comprimento e 1,9 ± 0,3 (1,2 – 2,4) μm de largura. A análise ultraestrutural revelou a presença de mitocôndrias alongadas distribuídas próximo a parede do plasmódio, diferentes estágios de desenvolvimento de mixosporos no interior do plasmódio, mixosporos com esporoplasma binucleado e filamento polar com 3 a 4 voltas no interior da cápsula polar. A partir de buscas feitas no BLASTn, com a sequência da menor unidade ribossomal do DNA (small subunit ribosomal DNA – ssrDNA), foi observado que a sequência obtida da espécie parasito da vesícula biliar de P. flavipinnis não corresponde a nenhuma outra disponível no GenBank, sendo Ceratomyxa gracillima e Ceratomyxa vermiformis as espécies com maior identidade, com 94% e 93% de similaridade respectivamente. A análise filogenética demonstrou que essa espécie agrupa em um subclado de espécies de Ceratomyxa de peixes amazônicos, e apresenta-se como espécie irmã de C. gracillima, que também infecta um peixe da família Pimelodidae. As análises morfológicas, ultraestruturais e moleculares demonstram que a espécie de Ceratomyxa infectando P. flavipinnis é uma espécie ainda não descrita na literatura.
The Amazon Basin is the biggest South American watershed. Composed by a diverse ichthyofauna, one of its main groups of fishes are the ones from the Pimelodidae family, being the species Pimelodina flavipinnis commonly found. The amazonian ichthyofauna is stricken by many pathogens, especially those of the class Myxozoa, endoparasitic cnidarians that have received great scientific attention in recent years. This study describes, for the first time, a species of Ceratomyxa infecting the gallbladder of Pimelodina flavipinnis. Twelve specimens of this fish were collected and examined in rio Solimões, being seven (58%) infected. The measures of the myxospores revealed mean of 4.6 ± 0.5 (3.4 – 5.5) μm of length, 31.2 ± 2.3 (26.2 – 36.3) μm of thickness, and 162 ± 10.4 (143 – 178)° of posterior angle. Polar capsules had 1,8 ± 0.3 (1.0 – 2.5) μm of length and 1.9 ± 0.3 (1.2 – 2.4) μm of width. The ultrastructural analysis revealed the presence of elongated mitochondria distributed near the plasmodial wall, different developmental stages of myxospores within the plasmodium, myxospores with binucleated sporoplasm and a polar filament with three to four turns inside the polar capsule. The BLASTn search showed that the sequence of the small subunit ribosomal DNA - ssrDNA does not correspond to any sequence deposited in GenBank, being Ceratomyxa gracillima and Ceratomyxa vermiformis the species with higher identity, 94% and 93% of similarity respectively. The phylogenetic analysis showed that this species clustered in a subclade together with Ceratomyxa species from amazonian fish and was placed as a sister species of C. gracillima, which also infects fish in the Pimelodidae family. The morphological, ultrastructural and molecular analysis show that Ceratomyxa sp. infecting P. flavipinnis is a species not yet described in the literature.
The Amazon Basin is the biggest South American watershed. Composed by a diverse ichthyofauna, one of its main groups of fishes are the ones from the Pimelodidae family, being the species Pimelodina flavipinnis commonly found. The amazonian ichthyofauna is stricken by many pathogens, especially those of the class Myxozoa, endoparasitic cnidarians that have received great scientific attention in recent years. This study describes, for the first time, a species of Ceratomyxa infecting the gallbladder of Pimelodina flavipinnis. Twelve specimens of this fish were collected and examined in rio Solimões, being seven (58%) infected. The measures of the myxospores revealed mean of 4.6 ± 0.5 (3.4 – 5.5) μm of length, 31.2 ± 2.3 (26.2 – 36.3) μm of thickness, and 162 ± 10.4 (143 – 178)° of posterior angle. Polar capsules had 1,8 ± 0.3 (1.0 – 2.5) μm of length and 1.9 ± 0.3 (1.2 – 2.4) μm of width. The ultrastructural analysis revealed the presence of elongated mitochondria distributed near the plasmodial wall, different developmental stages of myxospores within the plasmodium, myxospores with binucleated sporoplasm and a polar filament with three to four turns inside the polar capsule. The BLASTn search showed that the sequence of the small subunit ribosomal DNA - ssrDNA does not correspond to any sequence deposited in GenBank, being Ceratomyxa gracillima and Ceratomyxa vermiformis the species with higher identity, 94% and 93% of similarity respectively. The phylogenetic analysis showed that this species clustered in a subclade together with Ceratomyxa species from amazonian fish and was placed as a sister species of C. gracillima, which also infects fish in the Pimelodidae family. The morphological, ultrastructural and molecular analysis show that Ceratomyxa sp. infecting P. flavipinnis is a species not yet described in the literature.