Resumen de Electrophoretic protein profiles of mid-sized copepod Calanoides patagoniensis steadily fed bloom-forming diatoms
Victor M. Aguilera, Rubén Escribano, José Martínez Oyanedel
- español
Recent field and experimental evidence collected in southern upwelling region of the Humboldt Current showed a rapid decline (72 h) in the egg production rate (EPR) of copepods when they were fed steadily and solely with the local bloom-forming diatom Thalassiosira rotula. This phenotypic outcome may be associated to changes in the structure of protein profiles. This hypothesis was tested through the comparison of the structure of protein profiles (i.e., number and intensity of electrophoretic bands) elaborated with adult and eggs of the mid-sized copepod Calanoides patagoniensis assessing two food conditions leading to different EPR: T. rotula (low) and Prorocentrum minimum (high). The structure of protein profiles resulted similar mostly at banding region of 100 to 89-kDa where nutritional complexes have been previously found. However, the band at 56-kDa, where different stress-related proteins haven been found, was only observed with T. rotula. Since egg viability was independent of food treatments and thus, embryos nutritional requirements should have been satisfied; current findings suggest us that the EPR decline may have obeyed to post-digestive processes associated to the sustained diatoms-based diet. Thus, implications for copepod reproductive performance under intense spring-summer diatoms bloom occurring in the study area are discussed.
- English
Recent field and experimental evidence collected in the southern upwelling region off Concepción (36°5’S, 73°3’W) showed an abrupt reduction (<72 h) in the egg production rates (EPR) of copepods when they were fed steadily and solely with the local bloom-forming diatom Thalassiosira rotula. Because diatoms were biochemically similar to dinoflagellate Prorocentrum minimum, a diet which supported higher reproductive outcomes, the fecundity reduction observed in copepod females fed with the diatom may have obeyed to post-ingestive processes, giving rise to resources reallocation. This hypothesis was tested by comparing feeding (clearance and ingestion rates), reproduction (EPR and hatching success) and the structure of protein profiles (i.e., number and intensity of electrophoretic bands) of copepods (adults and eggs) incubated during 96 h with the two food conditions. The structure of protein profiles included molecular sizes that were calculated from the relative mobility of protein standards against the logarithm of their molecular sizes. After assessing the experimental conditions, feeding decreased over time for those females fed with T. rotula, while reproduction was higher in females fed with P. minimum. Electrophoretic profiles resulted similar mostly at a banding region of 100 to 89-kDa, while they showed partial differences around the region of 56-kDa band, especially in those females fed and eggs produced with T. rotula. Due to reproductive volume was impacted while larvae viability, a physiological processes with specific and high nutritional requirements, was independent on food type; post-ingestive processes, such as expression of stress-related proteins deviating resources to metabolic processes others than reproduction, are discussed under framework of nutritional-toxic mechanisms mediating copepod-diatoms relationships in productive upwelling areas.
