Characterization of fillets of Amazon and real hybrid sorubins / Caracterización de filetes de sorubinas híbridas amazónica y real

Background: Many fish hybrids (i.e., obtained by crossing two species) are produced rather than pure species because of their better growth rate and/or acceptance of formulated feed. However, few studies evaluate and compare their meats and acceptance, including, e.g., for the Amazon hybrid sorubim (Pseudoplatystoma reticulatum x Leiarius marmoratus) and the real hybrid sorubim (Pseudoplatystoma corruscans x L. marmoratus). Objective: Thus, this work aimed to evaluate the physical, chemical, microbiological, and sensory characteristics of fillets from the Amazon and real hybrid sorubins. Method:Proximate composition, instrumental color, water holding capacity, cooking losses, and shear force were measured.Microbiological analyses of the fillets were carried out for Salmonellasp. and Staphylococcusaureus to ensure food safety during sensory analysis. Results: Fillets presented excellent quality, classified in category A (lipids below 5% and proteins between 15 and 20%). There was no significant difference (p>0.05) between the evaluated fillets for several parameters: the average water holding capacities were 33.72 and 34.67%, the cooking losses were 14.93 and 13.41%, the shear forces were 2.21 and 1.74 kgf, and the luminosities were 49.61 and 45.04 for the fillets of Amazonian hybrid sorubim and real hybrid sorubim, respectively. Discussion: There was an evident relationship between water-holding capacities and shear forces. Amazonian hybrid sorubim fillets presented lower intensity of red. However, there was no sensory difference between the hybrids, and both had an acceptance rate above 80%. Conclusion: The hybridization does not alter the characteristics of the fish fillets

Antecedentes: Muchos híbridos de peces (i.e., obtenidos al cruzar dos especies) se producen en lugar de especies puras debido a su mejor tasa de crecimiento y/o aceptación de alimentos formulados. Sin embargo, pocos estudios evalúan y comparan sus carnes y aceptación, incluyendo, p. ej., para lo surubí híbrido amazónico (Pseudoplatystoma reticulatum x Leiarius marmoratus) y lo surubí híbrido real (Pseudoplatystoma corruscans x L. marmoratus). Objetivo: Así, el objetivo de este trabajo fue evaluar las características físicas, químicas, microbiológicas y sensoriales de filetes sorubines híbridos amazónico y real. Método: Se midió composición proximal, color instrumental, capacidad de retención de agua, pierdas por cocción y fuerza de corte. Se realizaron análisis microbiológicos de los filetes para Salmonella sp. y Staphylococcus aureus para garantizar la seguridad alimentaria durante el análisis sensorial. Resultados: Los filetes presentaron una excelente calidad, siendo clasificados en la categoría A (lípidos por debajo del 5% y proteínas entre 15 y 20%). No hubo diferencia significativa (p>0.05) entre los filetes evaluados para varios parámetros: las capacidades de retención de agua fueron 33.72 y 34.67%, las pierdas por cocción fueron 14.93 y 13.41%, las fuerzas de corte fueron 2.21 y 1.74 kgf y las luminosidades fueron 49.61 y 45.04 para los filetes de sorubim híbrido amazónico y sorubim híbrido real, respectivamente. Discusión: Hubo una relación evidente entre las capacidades de retención de agua y las fuerzas de corte. Los filetes de sorubim híbridos amazónicos presentaron menor intensidad de rojo. Sin embargo, no hubo diferencia sensorial entre los híbridos, y ambos tuvieron una tasa de aceptación superior al 80%. Conclusión: La hibridación no altera las características de los filetes de pescado

Eritrograma de híbridos de surubim (Pseudoplatystoma reticulatum X P. coruscans) mantidos em diferentes densidades de estocagem / Erythrogram of hybrids surubins (Pseudoplatystoma coruscans X P. reticulatum) kept at different stocking densities

The blood profile of hybrid fish was studied. Pseudoplatystoma (P. coruscans X P. reticulatum) were submitted to different stocking densities in recirculating water system in two distinct phases of production. Hemoglobin concentration (Hg), packed cell volume (PCV) and mean corpuscular hemoglobin concentration (MCHC) were evaluated. There was no difference between the studied densities. Hemoglobin concentration, PCV and MCHC remained within the normal range for teleost fish.

Karyotype variability in neotropical catfishes of the family pimelodidae (Teleostei: Siluriformes)

Dados cariotípicos são apresentados para quatro espécies da família Pimelodidae. Todas apresentaram o mesmo número diploide, 2n = 56 cromossomos, com diferenças nas fórmulas cariotípicas. As espécies aqui analisadas mostraram pouca quantidade de heterocromatina localizada preferencialmente na região centromérica e telomérica de alguns cromossosmos do complemento cariotípico. As regiões organizadoras de nucléolo (Ag-RONs) e a localização dos genes ribossomais pela hibridização in situ fluorescente (FISH), com sondas 18S e 5S, evidenciaram somente um par cromossômico marcado portador de genes ribossomais, à exceção de Pimelodus britskii que apresentou NORs múltiplas e localização sintênica das sondas 18S e 5S. Eventos não-Robertsonianos, como inversão pericêntrica e duplicação das NORs são requeridos para explicar a diversificação cariotípica em Pseudoplatystoma do rio Paraguai (MS), Pimelodus do rio Iguaçu (PR), Sorubim do rio Paraguai (MS) e Steindachneridion do rio Paraíba do Sul (SP). Os dados obtidos para a macroestrutura cariotípica destas espécies corrobora um padrão conservado observado na família Pimelodidae. Por outro lado, evidências de variações interespecíficas pelos marcadores de citogenética molecular empregados possibilitam inferências citotaxonômicas e diferenciação das espécies aqui analisadas.

Karyotypic data are presented for four species of fish belonging to the Pimelodidae family. These species show a conserved diploid number, 2n = 56 chromosomes, with different karyotypic formulae. The analyzed species showed little amount of heterochromatin located preferentially in the centromeric and telomeric regions of some chromosomes. The nucleolus organizer regions activity (Ag-NORs) and the chromosomal location of ribosomal genes by fluorescent in situ hybridization (FISH), with 18S and 5S probes, showing only one chromosome pair marked bearer of ribosomal genes, the only exception was Pimelodus britskii that presented multiple NORs and syntenic location of the 18S and 5S probes. Non-Robertsonian events, as pericentric inversion and NORs duplication are requested to explain the karyotype diversification in Pseudoplatystoma from the rio Paraguay (MS), Pimelodus from the rio Iguaçu (PR), Sorubim from the rio Paraguay (MS) and Steindachneridion from the rio Paraíba do Sul (SP). The obtained data for the karyotype macrostructure of these species corroborates a conserved pattern observed in Pimelodidae. On the other hand, interspecific variations detected by molecular cytogenetics markers made possible cytotaxonomic inferences and differentiation of the species here analyzed.