Proteomics profiling of epidermal mucus secretion of a cichlid (Symphysodon aequifasciata) demonstrating parental care behavior

Abstract

The discus fish (Symphysodon aequifasciata) is a cichlid demonstrating advanced mode of parental care towards fry. Both male and female fish utilized epidermal mucus secreted from specialized epidermal cells to feed developing fry. We utilized proteomics to compare protein profile from parental and nonparental fish. Gel analysis revealed a total of 35 spots that were up-regulated in parental mucus. In tandem, another 18 spots were uniquely expressed in parental mucus. MS analysis of these spots identified proteins such as fructose biphosphate aldolase, nucleoside diphosphate kinase, and heat shock proteins, which are essential to support energy provision, cell repair and proliferation, stress mediation, and defense mechanism in parental fish during parental-care period. Concurrently, the detection of several antioxidant-related proteins such as thioredoxin peroxidase and hemopexin suggests a need to overcome oxidative stress during hypermucosal production in parental-care behavior. A C-type lectin was also found to be uniquely expressed in parental mucus and could have important role in providing antimicrobial defense to both parental fish and fry. In summary, our study shows that discus mucus proteome undergoes changes in protein expression during parental-care period.

Differential proteome profile of skin mucus of gilthead seabream (Sparus aurata) after probiotic intake and/or overcrowding stress

“…In our experience working with proteomic tools [33,34] and taking into account previous proteomic studies [13,14,24], 2-DE followed by coupled tandem LC-MS/MS provides good resolution for comparatives studies. Furthermore, the development of fluorescent dyes from SYPRO group get great performance (in terms of linear range and limit of detection) [35], compared with other classical dyes such as silver or Coomassie brilliant blue.…”

Proteomics of Buccal Cavity Mucus in Female Tilapia Fish (Oreochromis spp.): A Comparison between Parental and Non-Parental Fish

“…Peptide mixture was spotted onto the MALDI target plate, allowed to dry prior to mass spectrometry analysis. Mass spectrometry was performed using the 4800 MALDI-TOF/TOF Analyzer (Applied Biosystems, Framingham, Massachusetts) using settings and parameters described earlier [18]. MS-MS/MS data was interpreted using Data Explorer version 4.9 (Applied Biosystem).…”

“…In tilapia ( O. mossambica ), there are mouthbrooding-related variations in concentration of various oral mucosal substances, including mucins and glycoproteins [17]. In addition, we previously demonstrated the occurrence of biochemical changes in the epidermal mucus of parental discus fish during parental care phase, and deduced that these changes could possibily be crucial to larval development and protection of parental fish [18], [19]. Insights on the protein composition of oral mucus of mouthbrooders in relation to mouthbrooding activities may provide useful knowledge on the functional aspects of this behavior.…”

The role of prolactin in fish reproduction

“…Mucous production in these species is associated with osmoregulation, but in other species of fish, particularly discus, this mucous is actively fed on by developing fry (note that this mucous is different to the buccal mucous produced by nest building species discussed in Section 4.3.2). The contents of the parental mucous, also known as 'discus milk', are currently under investigation, and compounds contained within it have been suggested to be involved in both fry nutrition and parent/offspring immune function [23,24].…”