The vertebrate Aqp14 water channel is a neuropeptide-regulated polytransporter

Water channels (aquaporins) were originally discovered in mammals with fourteen subfamilies now identified (AQP0-13). Here we show that a functional Aqp14 subfamily phylogenetically related to AQP4-type channels exists in all vertebrate lineages except hagfishes and eutherian mammals. In contrast to the water-selective classical aquaporins, which have four aromatic-arginine constriction residues, Aqp14 proteins present five non-aromatic constriction residues and facilitate the permeation of water, urea, ammonia, H2O2 and glycerol. Immunocytochemical assays suggest that Aqp14 channels play important osmoregulatory roles in piscine seawater adaptation. Our data indicate that Aqp14 intracellular trafficking is tightly regulated by the vasotocinergic/isotocinergic neuropeptide and receptor systems, whereby protein kinase C and A transduction pathways phosphorylate highly conserved C-terminal residues to control channel plasma membrane insertion. The neuropeptide regulation of Aqp14 channels thus predates the vasotocin/vasopressin regulation of AQP2-5-6 orthologs observed in tetrapods. These findings demonstrate that vertebrate Aqp14 channels represent an ancient subfamily of neuropeptide-regulated polytransporters.publishedVersio

Lineage-level divergence of copepod glycerol transporters and the emergence of isoform-specific trafficking regulation

Transmembrane conductance of small uncharged solutes such as glycerol typically occurs through aquaglyceroporins (Glps), which are commonly encoded by multiple genes in metazoan organisms. To date, however, little is known concerning the evolution of Glps in Crustacea or what forces might underly such apparent gene redundancy. Here, we show that Glp evolution in Crustacea is highly divergent, ranging from single copy genes in species of pedunculate barnacles, tadpole shrimps, isopods, amphipods and decapods to up to 10 copies in diplostracan water fleas although with monophyletic origins in each lineage. By contrast the evolution of Glps in Copepoda appears to be polyphyletic, with surprisingly high rates of gene duplication occurring in a genera- and species-specific manner. Based upon functional experiments on the Glps from a parasitic copepod (Lepeophtheirus salmonis), we show that such lineage-level gene duplication and splice variation is coupled with a high rate of neofunctionalization. In the case of L. salmonis, splice variation of a given gene resulted in tissue- or sex-specific expression of the channels, with each variant evolving unique sites for protein kinase C (PKC)- or protein kinase A (PKA)-regulation of intracellular membrane trafficking. The combined data sets thus reveal that mutations favouring a high fidelity control of intracellular trafficking regulation can be a selection force for the evolution and retention of multiple Glps in copepods.publishedVersio

A transcriptomic analysis of diploid and triploid Atlantic salmon lenses with and without cataracts

To avoid negative environmental impacts of escapees and potential inter-breeding with wild populations, the Atlantic salmon farming industry has and continues to extensively test triploid fish that are sterile. However, they often show differences in performance, physiology, behavior and morphology compared to diploid fish, with increased prevalence of vertebral deformities and ocular cataracts as two of the most severe disorders. Here, we investigated the mechanisms behind the higher prevalence of cataracts in triploid salmon, by comparing the transcriptional patterns in lenses of diploid and triploid Atlantic salmon, with and without cataracts. We assembled and characterized the Atlantic salmon lens transcriptome and used RNA-seq to search for the molecular basis for cataract development in triploid fish. Transcriptional screening showed only modest differences in lens mRNA levels in diploid and triploid fish, with few uniquely expressed genes. In total, there were 165 differentially expressed genes (DEGs) between the cataractous diploid and triploid lens. Of these, most were expressed at lower levels in triploid fish. Differential expression was observed for genes encoding proteins with known function in the retina (phototransduction) and proteins associated with repair and compensation mechanisms. The results suggest a higher susceptibility to oxidative stress in triploid lenses, and that mechanisms connected to the ability to handle damaged proteins are differentially affected in cataractous lenses from diploid and triploid salmon.publishedVersionUnit Licence Agreemen

The lineage-specific evolution of aquaporin gene clusters facilitated tetrapod terrestrial adaptation

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

Phylogenomic and functional analyses of salmon lice aquaporins uncover the molecular diversity of the superfamily in Arthropoda

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

Auto-Adhesion Potential of Extraocular Aqp0 during Teleost Development

AQP0 water channels are the most abundant proteins expressed in the mammalian lens fiber membranes where they are essential for lens development and transparency. Unlike other aquaporin paralogs, mammalian AQP0 has a low intrinsic water permeability, but can form cell-to-cell junctions between the lens fibers. It is not known whether the adhesive properties of AQP0 is a derived feature found only in mammals, or exists as a conserved ancestral trait in non-mammalian vertebrates. Here we show that a tetraploid teleost, the Atlantic salmon, expresses four Aqp0 paralogs in the developing lens, but also expresses significant levels of aqp0 mRNAs and proteins in the epithelia of the pronephros, presumptive enterocytes, gill filament and epidermis. Quantitative PCR reveals that aqp0 mRNA titres increase by three orders of magnitude between the onset of somitogenesis and pigmentation of the eye. Using in situ hybridization and specific antisera, we show that at least two of the channels (Aqp0a1, -0b1 and/or -0b2) are localized in the extraocular basolateral and apical membranes, while Aqp0a2 is lens-specific. Heterologous expression of the Aqp0 paralogs in adhesion-deficient mouse fibolast L-cells reveals that, as for human AQP0, each intact salmon channel retains cell-to-cell adhesive properties. The strongest Aqp0 interactions are auto-adhesion, suggesting that homo-octamers likely form the intercellular junctions of the developing lens and epithelial tissues. The present data are thus the first to show the adhesion potential of Aqp0 channels in a non-mammalian vertebrate, and further uncover a novel extraocular role of the channels during vertebrate development

Tree layer stucture of the ash forest in Kemere National Park

Ošu audžu kritiskais stāvoklis un straujie samazināšanās tempi Latvijā, kā arī citviet Eiropā, rada bažas par ilgtspējīgu ošu audžu pieejamību. Darbs ir izstrādāts ar mērķi analizēt Ķemeru nacionālajā parkā esošas ošu mitrāju kokaudzes sugu sastāvu un uzbūvi, kā arī prognozēt kokaudzes sugu sastāva izmaiņas nākotnē. Darbā tiek analizēts sugu sastāvs kokaudzē un pamežā, noteikti un analizēti kokaudzes taksācijas elementi, analizēts kokaudzes stāvojums un krāja, kā arī noteiktas sugu sastāva mainības tendences. Darbā ir sniegta informācija arī par Parastā oša (Fraxinus excelsior) bioloģiju un ekoloģiju, kā arī par ošu audžu izplatību Latvijā. Darba apjoms: 55 lappuses bez pielikumiem, 21 attēls, 9 tabulas un 11 pielikumi, kā arī atsauces uz 35 literatūras avotiem. Atslēgvārdi: Osis, Fraxinus excelsior, Ķemeru nacionālais parks, kokaudze, sugu sastāvs, krājaCritical situation of ash tree forests and their fast reducing speed in Latvia, also in other places over Europe, raise doubts about sustainable ash tree forest availability. The purpose of my bachelor work is to analyse the ash tree forest species composition and its structure, to forecast forest species compositional changes in future in The Kemeri National Park. Species composition in the ash tree forest and underbrush are analysed in my bachelor, also there are defined and analysed forest taxation elements, analysed forest layering and growing stock, defined species composition fluctuation tendencies. In my bachelor also is given information about ash tree (Fraxinus excelsior) biology and ecology and ash tree forests prevalence range in Latvia. Bachelor contains 55 pages, 21 figures, 9 tables, 11 annexes and there are 35 references. Keywords: Ash tree, Fraxinus excelsior, Kemeri National Park, species composition, growing stock, Ash tree fores

The vertebrate Aqp14 water channel is a neuropeptide-regulated polytransporter

Water channels (aquaporins) were originally discovered in mammals with fourteen subfamilies now identified (AQP0-13). Here we show that a functional Aqp14 subfamily phylogenetically related to AQP4-type channels exists in all vertebrate lineages except hagfishes and eutherian mammals. In contrast to the water-selective classical aquaporins, which have four aromatic-arginine constriction residues, Aqp14 proteins present five non-aromatic constriction residues and facilitate the permeation of water, urea, ammonia, H2O2 and glycerol. Immunocytochemical assays suggest that Aqp14 channels play important osmoregulatory roles in piscine seawater adaptation. Our data indicate that Aqp14 intracellular trafficking is tightly regulated by the vasotocinergic/isotocinergic neuropeptide and receptor systems, whereby protein kinase C and A transduction pathways phosphorylate highly conserved C-terminal residues to control channel plasma membrane insertion. The neuropeptide regulation of Aqp14 channels thus predates the vasotocin/vasopressin regulation of AQP2-5-6 orthologs observed in tetrapods. These findings demonstrate that vertebrate Aqp14 channels represent an ancient subfamily of neuropeptide-regulated polytransporters

The vertebrate Aqp14 water channel is a neuropeptide-regulated polytransporter

Water channels (aquaporins) were originally discovered in mammals with fourteen subfamilies now identified (AQP0-13). Here we show that a functional Aqp14 subfamily phylogenetically related to AQP4-type channels exists in all vertebrate lineages except hagfishes and eutherian mammals. In contrast to the water-selective classical aquaporins, which have four aromatic-arginine constriction residues, Aqp14 proteins present five non-aromatic constriction residues and facilitate the permeation of water, urea, ammonia, H2O2 and glycerol. Immunocytochemical assays suggest that Aqp14 channels play important osmoregulatory roles in piscine seawater adaptation. Our data indicate that Aqp14 intracellular trafficking is tightly regulated by the vasotocinergic/isotocinergic neuropeptide and receptor systems, whereby protein kinase C and A transduction pathways phosphorylate highly conserved C-terminal residues to control channel plasma membrane insertion. The neuropeptide regulation of Aqp14 channels thus predates the vasotocin/vasopressin regulation of AQP2-5-6 orthologs observed in tetrapods. These findings demonstrate that vertebrate Aqp14 channels represent an ancient subfamily of neuropeptide-regulated polytransporters