Mucus

Along the coast of Baja California Sur, spiny red lobster Panulirus interruptus is marketed and exported live. During the fishing season, water temperature varies from subtropical to temperate and transportation of live lobsters may exceed 24 h. This experiment simulated live lobster transport using lobsters that had been acclimated for 48 h at either 20 °C or 26 °C. Lobsters were then placed in Styrofoam containers, covered with sawdust, and remained in this condition for 3, 6, 12, or 24 h. After each treatment, lobster gills were dissected for histological analysis. There was a significant effect (p < 0.05) of temperature and emersion time on gill lamellae area, perimeter, and form factor. Gill lamellae area and form factor significantly decreased (7% and 13%) for lobster acclimated at 26 °C, while the perimeter increased (3%). After emersion for 24 h, the contact surface for respiratory exchange had significantly decreased, while the form factor increased. Based on these results, we developed an index of gill collapse to relate loss of lamellae form and respiratory function. After 24 h of emersion, 69% of the gill lamellae had collapsed at 26 °C, but at 20 °C, only 28% of the gill lamellae had collapsed. These changes had no effect on the survival of spiny red lobster, suggesting a morpho-physiological mechanism of tolerance to emersion, in which the shape and area of the gill lamellae recovers by producing mucus (mucopolysaccharides or glycosaminoglycans).

En Baja California Sur se comercializa y transporta viva la langosta roja, Panulirus interruptus. Durante la temporada de captura la temperatura del agua puede variar de condiciones semi-tropicales a templadas mientras que los tiempos de traslado al punto de venta pueden superar las 24 h. Se realizó un experimento donde se aclimataron langostas por 48 h a dos temperaturas experimentales (20 y 26°C) para después simular en el laboratorio el transporte en vivo. Las langostas fueron colocadas en hieleras de poliuretano, cubiertas con aserrín y la hielera sellada para simular tiempos de traslado de 3, 6, 12, 24 h durante los cuales las langostas permanecieron en emersión. Pasado el tiempo de emersión se sacrificaron 15 langostas por tratamiento, se disecaron las branquias y se realizaron cortes histológicos para evaluar los cambios morfológicos de las lamelas branquiales en P. interruptus. Los resultados mostraron un efecto significativo (p<0.05) de la temperatura, del tiempo de emersión, y de la interacción en el área, factor de forma y perímetro de las lamelas branquiales. El área y el factor de forma de las lamelas branquiales disminuyen significativamente (7 y 13%) a la mayor temperatura mientras que el perímetro se incrementa (3%). A las 24 h de emersión la superficie para intercambio respiratorio disminuye significativamente mientras que el factor de forma se incrementa. En base a los resultados se propone el índice de colapsamiento (IC) como un indicador de pérdida en la forma y el funcionamiento de la lamela branquial. El 69% de las lamelas branquiales se colapsaron a 26°C a las 24 h de emersión mientras a 20°C solamente el 28% de las lamelas branquiales se colapsaron. Estos cambios no repercuten en la sobrevivencia de P. interruptus lo que sugieren un mecanismo morfo-fisiológico de tolerancia a la emersión que le permite recuperar el área y la forma de la lamela basado en la producción de mucinas (mucopolisacaridos o glicosaminoglicanos).

Vibrio salmonicida is the causative agent of cold-water vibriosis in farmed marine fish species. Adherence of pathogenic bacteria to mucosal surfaces is considered to be the first steps in the infective processes, and proteins involved are regarded as virulence factors. The global protein expression profile of V. salmonicida, grown with and without the presence of fish skin mucus in the synthetic media, was compared. Increased levels of proteins involved in motility, oxidative stress responses, and general stress responses were demonstrated as an effect of growth in the presence of mucus compared to non-mucus containing media. Enhanced levels of the flagellar proteins FlaC, FlaD and FlaE indicate increased motility capacity, while enhanced levels of the heat shock protein DnaK and the chaperonin GroEL indicate a general stress response. In addition, we observed that peroxidases, TPx.Grx and AhpC, involved in the oxidative stress responses, were induced by mucus proteins. The addition of mucus to the culture medium did not significantly alter the growth rate of V. salmonicida. An analysis of mucus proteins suggests that the mucus layer harbours a protein species that potentially possesses catalytic activity against DNA, and a protein with iron chelating activity. This study represents the first V. salmonicida proteomic analysis, and provides specific insight into the proteins necessary for the bacteria to challenge the skin mucus barrier of the fish.