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Aerobic metabolic rates of embryos and larvae of Atlantic cod (Gadus morhua) and turbot (Scophthalmus maximus) were measured and used stoichiometrically to balance the substrates, in the form of free amino acids (FAAs), proteins and lipids, that quantitatively disappeared during development. Calculations reveal that cod embryos and larvae predominantly fuel their metabolism with FAAs (73%) throughout development; in addition, following closure of the blastopore, lipid is also steadily catabolized (27%). Turbot, however, utilize different substrates at separate stages of development. FAAs are predominantly burned during the embryonic stage, while lipids are burned during the yolk-sac stage. From the time of first-feeding, proteins are recruited from body stores and catabolized. Thus, for turbot, free and protein-bound amino acids together contribute 40% to the energy metabolism, while lipids contribute 60%.Article from Marine Science Symposia Vol. 201 - "Mass rearing of juvenile fish". Symposium held in Bergen, 21-23 June 1993. To access the remaining articles please click on the keyword "MSS Vol. 201".

Transmembrane glycerol transport is an ancient biophysical property that evolved in selected subfamilies of water channel (aquaporin) proteins. Here, we conducted broad level genome (>550) and transcriptome (>300) analyses to unravel the duplication history of the glycerol-transporting channels (glps) in Deuterostomia. We found that tandem duplication (TD) was the major mechanism of gene expansion in echinoderms and hemichordates, which, together with whole genome duplications (WGD) in the chordate lineage, continued to shape the genomic repertoires in craniates. Molecular phylogenies indicated that aqp3-like and aqp13-like channels were the probable stem subfamilies in craniates, with WGD generating aqp9 and aqp10 in gnathostomes but aqp7 arising through TD in Osteichthyes. We uncovered separate examples of gene translocations, gene conversion, and concerted evolution in humans, teleosts, and starfishes, with DNA transposons the likely drivers of gene rearrangements in paleotetraploid salmonids. Currently, gene copy numbers and BLAST are poor predictors of orthologous relationships due to asymmetric glp gene evolution in the different lineages. Such asymmetries can impact estimations of divergence times by millions of years. Experimental investigations of the salmonid channels demonstrated that approximately half of the 20 ancestral paralogs are functional, with neofunctionalization occurring at the transcriptional level rather than the protein transport properties. The combined findings resolve the origins and diversification of glps over >800 million years old and thus form the novel basis for proposing a pandeuterostome glp gene nomenclature

14 pages, 5 figures, electronic supplementary material https://doi.org/10.1186/s12864-015-1814-8, Background: An emerging field in biomedical research is focusing on the roles of aquaporin water channels in parasites that cause debilitating or lethal diseases to their vertebrate hosts. The primary vectorial agents are hematophagous arthropods, including mosquitoes, flies, ticks and lice, however very little is known concerning the functional diversity of aquaporins in non-insect members of the Arthropoda. Here we conducted phylogenomic and functional analyses of aquaporins in the salmon louse, a marine ectoparasitic copepod that feeds on the skin and body fluids of salmonids, and used the primary structures of the isolated channels to uncover the genomic repertoires in Arthropoda. Results: Genomic screening identified 7 aquaporin paralogs in the louse in contrast to 42 in its host the Atlantic salmon. Phylogenetic inference of the louse nucleotides and proteins in relation to orthologs identified in Chelicerata, Myriapoda, Crustacea and Hexapoda revealed that the arthropod aquaporin superfamily can be classified into three major grades (1) classical aquaporins including Big brain (Bib) and Prip-like (PripL) channels (2) aquaglyceroporins (Glp) and (3) unorthodox aquaporins (Aqp12-like). In Hexapoda, two additional subfamilies exist as Drip and a recently classified entomoglyceroporin (Eglp) group. Cloning and remapping the louse cDNAs to the genomic DNA revealed that they are encoded by 1-7 exons, with two of the Glps being expressed as N-terminal splice variants (Glp1_v1, -1_v2, -3_v1, -3_v2). Heterologous expression of the cRNAs in amphibian oocytes demonstrated that PripL transports water and urea, while Bib does not. Glp1_v1, -2, -3_v1 and -3_v2 each transport water, glycerol and urea, while Glp1_v2 and the Aqp12-like channels were retained intracellularly. Transcript abundance analyses revealed expression of each louse paralog at all developmental stages, except for glp1_v1, which is specific to preadult and adult males. Conclusions: Our data suggest that the aquaporin repertoires of extant arthropods have expanded independently in the different lineages, but can be phylogenetically classified into three major grades as opposed to four present in deuterostome animals. While the aquaporin repertoire of Atlantic salmon represents a 6-fold redundancy compared to the louse, the functional assays reveal that the permeation properties of the different crustacean grades of aquaporin are largely conserved to the vertebrate counterparts. © 2015 Stavang et al., This work was supported by the Research Council of Norway (RCN) project 204813/F20 to R.N.F., the SFI-Sea Lice Research Centre, Grant No. 203513 to F.N., and the Spanish Ministry of Economy and Competitiveness (MINECO), project AGL2013-41196-R to JC. J.A.S. and F.C. were supported by postdoctoral fellowships from the RCN (204813/F20 and 224816/E40, respectively)

38 pages, 6 pages, 3 tables, supporting information https://doi.org/10.1371/journal.pone.0113686, A major physiological barrier for aquatic organisms adapting to terrestrial life is dessication in the aerial environment. This barrier was nevertheless overcome by the Devonian ancestors of extant Tetrapoda, but the origin of specific molecular mechanisms that solved this water problem remains largely unknown. Here we show that an ancient aquaporin gene cluster evolved specifically in the sarcopterygian lineage, and subsequently diverged into paralogous forms of AQP2,-5, or-6 to mediate water conservation in extant Tetrapoda. To determine the origin of these apomorphic genomic traits, we combined aquaporin sequencing from jawless and jawed vertebrates with broad taxon assembly of >2,000 transcripts amongst 131 deuterostome genomes and developed a model based upon Bayesian inference that traces their convergent roots to stem subfamilies in basal Metazoa and Prokaryota. This approach uncovered an unexpected diversity of aquaporins in every lineage investigated, and revealed that the vertebrate superfamily consists of 17 classes of aquaporins (Aqp0-Aqp16). The oldest orthologs associated with water conservation in modern Tetrapoda are traced to a cluster of three aqp2-like genes in Actinistia that likely arose >500 Ma through duplication of an aqp0-like gene present in a jawless ancestor. In sea lamprey, we show that aqp0 first arose in a protocluster comprised of a novel aqp14 paralog and a fused aqp01 gene. To corroborate these findings, we conducted phylogenetic analyses of five syntenic nuclear receptor subfamilies, which, together with observations of extensive genome rearrangements, support the coincident loss of ancestral aqp2-like orthologs in Actinopterygii. We thus conclude that the divergence of sarcopterygian-specific aquaporin gene clusters was permissive for the evolution of water conservation mechanisms that facilitated tetrapod terrestrial adaptation, This work was supported by the Research Council of Norway (RCN) project #178837/40 and 224816/E40 to (RNF), the Spanish Ministry of Science and Innovation (MICINN) AGL2010-15597 to (JC) and by the National Science Foundation, USA (NSF) IOS 0844818, 1041885 and 1241312 to (CPC). FC was supported by a postdoctoral (Juan de la Cierva Programme) fellowship from MICINN and the RCN (224816/E40)

The stage of spawning of females of the Arcto-Norwegian cod caught during peak spawning in Lofoten had a profound effect on several vital parameters of the eggs and larvae. Significant negative correlations were demonstrated between stage of spawning and size of eggs and larvae and total content of nonprotein amino compounds (NPS). Reduced larval activity was recorded in groups from cod females at the end of spawning. Investigations on the bacteriological status and the fatty acid profiles of the eggs are also included. The results are proposed in order to demonstrate a recruitment mechanism and are discussed in this connection.