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Smoltification is a complex process which involves morphological, physiological and behavioural changes which allow Atlantic salmon to migrate from fresh water to seawater. The biological interface between the salmon and their environment is the mucus coat, which is composed of a wide variety of biochemical secretions primarily from goblet cells on the surface of the epithelial layers, but also other cells such as sacciform cells and acidophilic granular cells. Skin mucus has been implicated in a diversity of roles including respiration, osmoregulation, reproduction, excretion, disease resistance, communication, feeding and protection ( Shepard, 1994). Further investigation is warranted with regard to the role of the mucus proteins in smoltification. This study is part of an ongoing investigation into the role of mucus proteins during smoltification using electrophoresis (1-D and 2-D). Mucus samples were taken from Atlantic salmon at the salmon management service. The samples were taken over the period of early March to late May (1999 and 2001). The band number and intensity of the bands was observed for each sampling date. No significant change in the band number was observed over the sampling dates or form one year to the next. The protein profile of the bands as shown by SDS-PAGE was conserved for all the samples. Significant variation in the intensity of three bands was however noted over time on I-D.A 14.9kDA protein increased in intensity over time. A second protein duplet in the 33-34kDa region decreased in intensity over time. Initial sequencing found that the 14.9kDa band contained histone H2B or H3. Up to sixty proteins were seen on 1-D. 2-D analysis of the samples showed more than 300 proteins. The change in the 33-34kDa proteins was not observed. Up to six proteins in the pI range4-7 were noted in this region. Up to eighteen proteins were noted in the 14.9kDa region, an number of which in the pI range 6-9 were found to increase in spot intensity. No homology to any known protein was found for these proteins. Two protein spots that were constantly present on al the 2-D gels were homologous to actin and apolipoprotein A-1 precursor (Atlantic salmon) respectively. The two spots that increased in intensity in 2001 were found to be homologous to keratin 13 and type II keratin E1 of Oncorhynchus mykiss (rainbow trout) respectively. No significant change in lysozyme activity or specific activity was noted over either year.
Kennedy, Paul (Thesis), "A biochemical study of Atlantic salmon (salmo salar) skin mucus proteins during smoltification (1999 and 2001)" (2004). Masters. Paper 36.