Analysis of two IgM isotypes in Atlantic salmon and brown trout.
ABSTRACT Atlantic salmon (Salmo salar) possesses two distinct subpopulations of polymeric IgM which are separable by anion exchange chromatography. Consistent with this finding there are two isotypic IgM heavy chain genes, CmuA and CmuB, in the genome of this species, presumably as a result of ancestral tetraploidy. In the present study it was shown that IgM of brown trout (Salmo trutta) is also separated into two subpopulations by anion exchange chromatography, while IgM of rainbow trout (Oncorhynchus mykiss) and Arctic char (Salvelinus alpinus) are eluted in one peak. Molecular cloning of IgM heavy chain cDNAs from brown trout revealed messages of two distinct constant region genes, named CmuA and CmuB. As deduced from the translated cDNA sequences (and in agreement with isoelectric focusing of the corresponding proteins) the mean pI values of the heavy chains in brown trout differ with only 0.14 units, in comparison to a 0.67 unit difference in salmon. Based on the present sequence analysis we suggest that an additional cysteine near the C-terminus of CmuB is critical in relation to the fractionation of IgM by anion exchange chromatography, for example by altering the overall structure of the IgM polymer and the exposure of charged residues. Most likely, the Cmu subvariant with the characteristic extra cysteine residue arose in the ancestor of Atlantic salmon and brown trout, i.e. after the three genera Salmo, Oncorhynchus and Salvelinus radiated.
SourceAvailable from: Iheanyi Omezuruike Okonko[Show abstract] [Hide abstract]
ABSTRACT: This study reports on the immune responses of fish to viral infections. In this review, the innate and acquired host immune responses of fish to viral infections will be considered. These would enable a more comprehensive understanding of fish immunity to viruses. The control of these viral infections are challenging as there are only a few treatments that are effective. Furthermore, the development of vaccines for the control of viruses remains elusive. Viruses are important pathogens affecting both wild and cultured fish. Teleost fish possess an array of defence mechanisms to prevent successful infections of these pathogens which abound in the surrounding aquatic environment. These mechanisms can be grouped as innate (non-specific) and adaptive (specific) immunity. Here the general protective immune mechanisms of fish to viral infections are reviewed. The fundamental components of innate and adaptive immunity present in finfish are similar to their mammalian counterparts in many ways. Once the physical barriers are overcome by the invading pathogen, chemical and genetic barriers kick in. Complement and interferon are part of such chemical barriers. Natural Killer cells also contribute to non-specific immunity through cell-mediated cytotoxicity (CMC). B-lymphocytes and T-lymphocytes are the major players in specific immune response and are the final defence against the pathogens. Developments in genomics have caused remarkable breakthroughs in insight into immune responses in finfish. However, quite a lot of ground remains to be covered. The zebra fish is currently being studied as a model to bridge the gaps in knowledge.Nature and Science of Sleep 06/2012; 10(8):70-76.
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ABSTRACT: The Brazilian organic food sector has experienced important growth during the last two decades. Brazilian smallholders, however, are facing huge challenges to enter and benefit from this growth in a sustainable way. Combining the lens of New Institutional Economics and socio-anthropology, we analyse six experiences of Brazilian smallholders who converted to organics in the 1990s’. Three different food systems are featured in this analysis: an alternative food system, which is strongly interwoven with the Brazilian Agro-ecological movement and two commercial food procurement systems oriented towards domestic and an export markets driven mainly by supermarket chains. The analytical focus was on 1) the governance of these food systems, 2) the constraints farmers are facing within these food systems and, 3) the benefits that they can expect from market inclusion. We highlighted the roles that NGOs, Faith-based organisations and public-related agencies play in supporting the inclusion of smallholders into all three food systems. We confirmed the arguments in support of pursuing the agro-ecological development based model in Brazil, but underlined that there is a critical lack of support for famers included in the commercial market-oriented food systems. Such a lack is even more critical as the food systems driven by expanding supermarket chains are characterised by strong asymmetric power relations at the expense of smallholders. Considering the reluctance of NGOs and Faith-based organisations to support these farmers, we call for efforts to be made to provide a policy framework to enable public related entities to secure sustainable inclusion into these systems and exit strategies for those experiencing exclusion from these highly competitive food systems.Journal of Rural Studies 01/2012; DOI:10.1016/j.jrurstud.2011.10.005 · 2.04 Impact Factor
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ABSTRACT: In the present article, immunoglobulin (Ig) of Puntius sarana (a vulnerable medium carp species) was purified by affinity chromatography, characterized, and identified as only IgM type with a native molecular weight of 879 kDa having one heavy (88 kDa) and one light (26 kDa) chain. Further, the developed rabbit antisera against IgM was found to be quite specific to P. sarana IgM and used in ELISA to measure the antibody titer in P. sarana at different time periods, against an antigen (hemocyanin) injection with and without adjuvant. The antibody titer was significantly higher in most of the time periods in both groups, however, the adjuvant-treated group showed higher antibody titer at days 43 and 90, compared to non adjuvant-treated group. Further, the partial IgM sequence was amplified and its expression level was checked during ontogenesis. The IgM transcript was detected from unfertilized egg stage to 4 days post fertilization (dpf) and again reappeared at 21 dpf whereas during infection with Aeromonas hydrophila, significantly marked up-regulation of the gene was observed at 12 hr, 24 hr, and 7 days post-infection time periods indicating the role of IgM during early embryonic time period as well as during bacterial pathogenesis.Journal of Immunoassay and Immunochemistry 03/2014; 35(3):269-87. DOI:10.1080/15321819.2013.848814 · 0.73 Impact Factor