Histopathological and phylogenetic description of an Amazonian cnidaria microparasite Myxobolus rousseauxii n. sp. infecting the gill arches of Brachyplatystoma rousseauxii (Siluriformes).

From genus Myxobolus, cnidarians of Myxozoa class, is well known for infecting economically important fish species and, as result, relevant losses in aquaculture production can be observed. They are present in a big range of fish in its natural habitat, including the migratory Brachyplatystoma rousseauxii catfish. This study aimed is to develop an integrative characterization of a new species of Myxobolus, located in B. rousseauxii's gills. To accomplish this, 30 specimens of B. rousseauxii catfish were collected from Mosqueiro Island in Pará, Brazil; necropsied and analyzed for morphology, histology and molecular characteristics. Cysts with conjunctival capsule development made up of fibroblasts were observed at the gill arches; such proliferation caused bone tissue loss and cartilage compression. The cysts contained Myxobolus myxospores measuring 9.9 µm of length and 9.6 µm of width, whereas polar capsules were 5.4 µm long and 3.4 µm wide, with 8 to 9 coils of polar tubules. Phylogenetic analyses revealed that new species were included in a subclade alongside species from the same geographic location and infection site that infect Siluriformes fish. Morphological and molecular differences revealed that Myxobolus spp. parasite-host associations through histopathology supporting the designation of a new M. rousseauxii n. sp. species in B. rousseauxii, a commercially important fish.

Kudoa rousseauxii n. sp. (Cnidaria: Multivalvulida) Infects the Skeletal Muscles of the Freshwater Fish Brachyplatystoma rousseauxii in the Amazon River.

PURPOSE: Members of the genus Kudoa Meglitsch, 1947 are known to infect the muscles of commercially important fishes worldwide, including those in the order Siluriformes. This paper describes the occurrence of a new species of Kudoa in the catfish Brachyplatystoma rousseauxii based on morphological study and molecular analysis of the ribosomal RNA gene (SSU rDNA). METHODS: Fifteen specimens of Brachyplatystoma rousseauxii were purchased from fishing zones near Mosqueiro Island, Belém, Pará, Brazil. After necropsy, tissue samples and cysts were analyzed using a stereomicroscope, and fresh slides were viewed under a light microscope to confirm parasitic infection. The tissue fragments were removed and processed for molecular and histological analyses. RESULTS: Microscopic pseudocysts were found in the epaxial region of skeletal muscle fibers in 80% of the analyzed specimens. The myxospores were quadrangular with four shell valves (SV), pyriform polar capsules (PC), and internal symmetry. Phylogenetic analyses indicated that the new species formed a cluster with the species previously described in the Amazon, being close to two freshwater species. CONCLUSIONS: Morphological differences and molecular data of SSU rDNA support that Kudoa rousseauxii n. sp. is a new species that infects B. rousseauxii, a freshwater fish with intense migratory cycles that is widely captured and consumed in the Amazon.

Qualidade de ovos brancos comercializados em diferentes estabelecimentos no município de Paragominas – PA / Quality of whit eggs marketed in different establishments in the municipality of Paragominas – PA

Objetivou-se verificar a qualidade de ovos brancos de acordo com os aspectos internos e externos comercializados em diferentes estabelecimentos do município de Paragominas - PA. Os ovos foram coletados de aleatoriamente em diferentes pontos comerciais. As análises consideradas no estudo, foi de: integridade e aparência da casca e peso do ovo, altura da câmara de ar, peso, altura e diâmetro da gema para o cálculo de índice da gema, altura e peso do albúmen e cor da gema. Os dados foram submetidos à análise de variância e ao teste de Tukey. Os ovos dos grandes supermercados apresentaram melhores índices de qualidade interna e os piores resultados quanto a peso, trincas visíveis e sujeiras. Os ovos de pequenos supermercados apresentaram o maior índice de trincas não visíveis e os de médio porte os menores índices de sujeiras e trincas.