Natural history of SLC11 genes in vertebrates: tales from the fish world

<p>Abstract</p> <p>Background</p> <p>The <it>SLC11A1/Nramp1 </it>and <it>SLC11A2/Nramp2 </it>genes belong to the <it>SLC11/Nramp </it>family of transmembrane divalent metal transporters, with <it>SLC11A1 </it>being associated with resistance to pathogens and <it>SLC11A2 </it>involved in intestinal iron uptake and transferrin-bound iron transport. Both members of the <it>SLC11 </it>gene family have been clearly identified in tetrapods; however <it>SLC11A1 </it>has never been documented in teleost fish and is believed to have been lost in this lineage during early vertebrate evolution. In the present work we characterized the <it>SLC11 </it>genes in teleosts and evaluated if the roles attributed to mammalian <it>SLC11 </it>genes are assured by other fish specific <it>SLC11 </it>gene members.</p> <p>Results</p> <p>Two different <it>SLC11 </it>genes were isolated in the European sea bass (<it>Dicentrarchus. labrax</it>), and named <it>slc11a2-α </it>and <it>slc11a2-β</it>, since both were found to be evolutionary closer to tetrapods <it>SLC11A2</it>, through phylogenetic analysis and comparative genomics. Induction of <it>slc11a2-α </it>and <it>slc11a2-β </it>in sea bass, upon iron modulation or exposure to <it>Photobacterium damselae </it>spp. <it>piscicida</it>, was evaluated in <it>in vivo </it>or <it>in vitro </it>experimental models. Overall, <it>slc11a2-α </it>was found to respond only to iron deficiency in the intestine, whereas <it>slc11a2-β </it>was found to respond to iron overload and bacterial infection in several tissues and also in the leukocytes.</p> <p>Conclusions</p> <p>Our data suggests that despite the absence of <it>slc11a1</it>, its functions have been undertaken by one of the <it>slc11a2 </it>duplicated paralogs in teleost fish in a case of synfunctionalization, being involved in both iron metabolism and response to bacterial infection. This study provides, to our knowledge, the first example of this type of sub-functionalization in iron metabolism genes, illustrating how conserving the various functions of the SLC11 gene family is of crucial evolutionary importance.</p

A full-body transcriptome and proteome resource for the European common carp.

BACKGROUND: The common carp (Cyprinus carpio) is the oldest, most domesticated and one of the most cultured fish species for food consumption. Besides its economic importance, the common carp is also highly suitable for comparative physiological and disease studies in combination with the animal model zebrafish (Danio rerio). They are genetically closely related but offer complementary benefits for fundamental research, with the large body mass of common carp presenting possibilities for obtaining sufficient cell material for advanced transcriptome and proteome studies. RESULTS: Here we have used 19 different tissues from an F1 hybrid strain of the common carp to perform transcriptome analyses using RNA-Seq. For a subset of the tissues we also have performed deep proteomic studies. As a reference, we updated the European common carp genome assembly using low coverage Pacific Biosciences sequencing to permit high-quality gene annotation. These annotated gene lists were linked to zebrafish homologs, enabling direct comparisons with published datasets. Using clustering, we have identified sets of genes that are potential selective markers for various types of tissues. In addition, we provide a script for a schematic anatomical viewer for visualizing organ-specific expression data. CONCLUSIONS: The identified transcriptome and proteome data for carp tissues represent a useful resource for further translational studies of tissue-specific markers for this economically important fish species that can lead to new markers for organ development. The similarity to zebrafish expression patterns confirms the value of common carp as a resource for studying tissue-specific expression in cyprinid fish. The availability of the annotated gene set of common carp will enable further research with both applied and fundamental purposes

Differences in the antibody response and survival of genetically different varieties of common carp (Cyprinus carpio L.) vaccinated with a commercial Aeromonas salmonicida/A. hydrophila vaccine and challenged with A. hydrophila

Males of two strains of carp, wild Duna (D), and inbred Szarvas 22 (22), were selected for high and low stress response. Two purebreds of D and 22, from randomly chosen parents and four crosses, 22 &times; 22-L (low stress response), 22 &times; 22-H (high stress response), 22 &times; D-L (low stress response) and 22 &times; D-H (high stress response) from selected stress response parents were produced and vaccinated with a commercial Aeromonas salmonicida/Aeromonas hydrophila vaccine and their circulating antibody response evaluated 1, 3, 5, and 7 weeks post-vaccination by ELISA. Significantly higher titres of circulatory antibodies against A. hydrophila were found in the families 22 and cross 22 &times; 22-L compared to other groups. The development of circulatory antibodies against A. hydrophila in all crosses having at least one D parent was low and remained low throughout the experiment. The level of circulatory antibodies against atypical A. salmonicida in the inbred strain increased following a booster vaccination with the highest values measured in inbred strain 22 and cross 22 &times; 22 L. The different varieties of carp had different levels of survival against experimental challenge with A. hydrophila. The greatest survival was obtained in strain 22 and cross 22 &times; 22-L, while ~90% of D wild carp and cross 22 &times; D (independent of their stress response) died. Survival results correlated well with the antibody response of the different groups: 22 and 22 &times; 22-L had the highest antibody titres against A. hydrophila and the greatest level of survival