ASPECTOS ECOLÓGICOS DEL TREMÁTODO INVASOR CENTROCESTUS FORMOSANUS (NISHIGORI, 1924) (TREMATODA: HETEROPHYIDAE) EN LA TILAPIA DEL NILO OREOCHROMIS NILOTICUS (LINNAEUS, 1758) (PERCIFORMES: CICHLIDAE), EN EL HUMEDAL LOS PANTANOS DE VILLA, LIMA, PERÚ

La tilapia del Nilo Oreochromis niloticus (Linnaeus, 1758) es un pez de agua dulce endémico originario de África. El objetivo del presente trabajo fue evaluar algunos aspectos ecológicos del tremátodo invasor Centrocestus formosanus (Nishigori, 1924) (Trematoda: Heterophyidae) en O. niloticus en los humedales de Pantanos de Villa, Lima, Perú. Durante febrero y octubre de 2012 se inspeccionaron parasitológicamente 20 ejemplares de O. niloticus recolectados en las lagunas Génesis y Marvilla en los humedales de Pantanos de Villa, Lima, Perú. Los peces tuvieron un peso y longitud promedio de 221.3 g ± 111.4 y 19.6 cm ± 4.24 cm, respectivamente. Las metacercarias de ectoparásitos invasores fueron catalogadas y evaluadas utilizando protocolos parasitológicos estándares. Durante todo el muestreo, se recolectaron un total de 130 trematodos de C. formosanus, con una prevalencia promedio del 60% de las tilapias del Nilo parasitadas por C. formosanus. El factor de condición relativo (kn), un indicador de la salud de los peces huéspedes, no fue influenciado por la presencia de C. formosanus. Centrocestus formosanus se ha registrado en aves y mamíferos, incluidos los humanos, que producen heterofiosis, una enfermedad emergente mundial en humanos transmitida por el consumo de pescado crudo. Centrocestus formosanus en Perú representa un potencial impacto zoonótico en la salud pública. En adición, se registró en branquias en un solo huésped, la presencia del ectoparásito dinozoario Amyloodinium ocellatum Brown & Hovasse, 1946, que puede causar alteraciones patológicas en peces marinos y ambientes salinos.

Transcriptome Analysis of Amyloodinium ocellatum Tomonts Revealed Basic Information on the Major Potential Virulence Factors

The ectoparasite protozoan Amyloodinium ocellatum (AO) is the etiological agent of amyloodiniosis in European seabass (Dicentrarchus labrax) (ESB). There is a lack of information about basic molecular data on AO biology and its interaction with the host. Therefore, de novo transcriptome sequencing of AO tomonts was performed. AO trophonts were detached from infested ESB gills, and quickly becoming early tomonts were purified by Percoll® density gradient. Tomont total RNA was processed and quality was assessed immediately. cDNA libraries were constructed using TruSeq® Stranded mRNA kit and sequenced using Illumina sequencer. CLC assembly was used to generate the Transcriptome assembly of AO tomonts. Out of 48,188 contigs, 56.12% belong to dinophyceae wherein Symbiodinium microadriaticum had 94.61% similarity among dinophyceae. Functional annotations of contigs indicated that 12,677 had associated GO term, 9005 with KEGG term. The contigs belonging to dinophyceae resulted in the detection of several peptidases. A BLAST search for known virulent factors from the virulence database resulted in hits to Rab proteins, AP120, Ribosomal phosphoprotein, Heat-shock protein70, Casein kinases, Plasmepsin IV, and Brucipain. Hsp70 and casein kinase II alpha were characterized in-silico. Altogether, these results provide a reference database in understanding AO molecular biology, aiding to the development of novel diagnostics and future vaccines.

Influence of Age on Stress Responses of White Seabream to Amyloodiniosis

Amyloodiniosis is a disease that represents a major bottleneck for semi-intensive aquaculture, especially in Southern Europe. The inefficacy of many of the treatments for this disease on marine fish produced in semi-intensive aquaculture has led to a new welfare approach to amyloodiniosis. There is already some knowledge of several welfare issues that lead to amyloodiniosis as well as the stress, physiological, and immunological responses to the parasite by the host, but no work is available about the influence of fish age on the progression of amyloodiniosis. The objective of this work was to determine if stress, hematological, and histopathological responses are age dependent. For that purpose, we determined the mortality rate, histopathological lesions, hematological indexes, and stress responses (cortisol, glucose, lactate, and total protein) in “Small” (total weight: 50 ± 5.1 g, age: 273 days after eclosion (DAE)) and “Big” (total weight: 101.3 ± 10.4 g, age: 571 DAE) white seabream (Diplodus sargus) subjected to an Amyloodinium ocellatum infestation (8000 dinospores mL−1) during a 24-h period. The results demonstrated a strong stress response to A. ocellatum, with marked differences in histopathological alterations, glucose levels, and some hematological indexes between the fish of the two treatments. This work elucidates the need to take in account the size and age of the fish in the development and establishment of adequate mitigating measures and treatment protocols for amyloodiniosis.