Evolution of AANAT: expansion of the gene family in the cephalochordate amphioxus

<p>Abstract</p> <p>Background</p> <p>The arylalkylamine <it>N</it>-acetyltransferase (AANAT) family is divided into structurally distinct vertebrate and non-vertebrate groups. Expression of vertebrate AANATs is limited primarily to the pineal gland and retina, where it plays a role in controlling the circadian rhythm in melatonin synthesis. Based on the role melatonin plays in biological timing, AANAT has been given the moniker "the Timezyme". Non-vertebrate AANATs, which occur in fungi and protists, are thought to play a role in detoxification and are not known to be associated with a specific tissue.</p> <p>Results</p> <p>We have found that the amphioxus genome contains seven <it>AANAT</it>s, all having non-vertebrate type features. This and the absence of <it>AANATs </it>from the genomes of Hemichordates and Urochordates support the view that a major transition in the evolution of the <it>AANATs </it>may have occurred at the onset of vertebrate evolution. Analysis of the expression pattern of the two most structurally divergent <it>AANAT</it>s in <it>Branchiostoma lanceolatum </it>(<it>bl</it>) revealed that they are expressed early in development and also in the adult at low levels throughout the body, possibly associated with the neural tube. Expression is clearly not exclusively associated with the proposed analogs of the pineal gland and retina. blAANAT activity is influenced by environmental lighting, but light/dark differences do not persist under constant light or constant dark conditions, indicating they are not circadian in nature. bfAANATα and bfAANATδ' have unusually alkaline (> 9.0) optimal pH, more than two pH units higher than that of vertebrate AANATs.</p> <p>Conclusions</p> <p>The substrate selectivity profiles of bfAANATα and δ' are relatively broad, including alkylamines, arylalkylamines and diamines, in contrast to vertebrate forms, which selectively acetylate serotonin and other arylalkylamines. Based on these features, it appears that amphioxus AANATs could play several roles, including detoxification and biogenic amine inactivation. The presence of seven AANATs in amphioxus genome supports the view that arylalkylamine and polyamine acetylation is important to the biology of this organism and that these genes evolved in response to specific pressures related to requirements for amine acetylation.</p

A star is born again: Methods for larval rearing of an emerging model organism, the False clownfish Amphiprion ocellaris

As interest increases in ecological, evolutionary, and developmental biology (Eco-Evo-Devo), wild species are increasingly used as experimental models. However, we are still lacking a suitable model for marine fish species, as well as coral reef fishes that can be reared at laboratory scales. Extensive knowledge of the life cycle of anemonefishes, and the peculiarities of their biology, make them relevant marine fish models for developmental biology, ecology, and evolutionary sciences. Here, we present standard methods to maintain breeding pairs of the anemonefish Amphiprion ocellaris in captivity, obtain regular good quality spawning, and protocols to ensure larval survival throughout rearing. We provide a detailed description of the anemonefish husbandry system and life prey culturing protocols. Finally, a “low-volume” rearing protocol useful for the pharmacological treatment of larvae is presented. Such methods are important as strict requirements for large volumes in rearing tanks often inhibit continuous treatments with expensive or rare compounds

Field-Based Metabolomics of Vitis vinifera L. Stems Provides New Insights for Genotype Discrimination and Polyphenol Metabolism Structuring

Grape accumulates numerous polyphenols with abundant health benefit and organoleptic properties that in planta act as key components of the plant defense system against diseases. Considerable advances have been made in the chemical characterization of wine metabolites particularly volatile and polyphenolic compounds. However, the metabotyping (metabolite-phenotype characterization) of grape varieties, from polyphenolic-rich vineyard by-product is unprecedented. As this composition might result from the complex interaction between genotype, environment and viticultural practices, a field experiment was setting up with uniform pedo-climatic factors and viticultural practices of growing vines to favor the genetic determinism of polyphenol expression. As a result, UPLC-MS-based targeted metabolomic analyses of grape stems from 8 Vitis vinifera L. cultivars allowed the determination of 42 polyphenols related to phenolic acids, flavonoids, procyanidins, and stilbenoids as resveratrol oligomers (degree of oligomerization 1–4). Using a partial least-square discriminant analysis approach, grape stem chemical profiles were discriminated according to their genotypic origin showing that polyphenol profile express a varietal signature. Furthermore, hierarchical clustering highlights various degree of polyphenol similarity between grape varieties that were in agreement with the genetic distance using clustering analyses of 22 microsatellite DNA markers. Metabolite correlation network suggested that several polyphenol subclasses were differently controlled. The present polyphenol metabotyping approach coupled to multivariate statistical analyses might assist grape selection programs to improve metabolites with both health-benefit potential and plant defense traits

Neuroendocrinology of Life History and Stress in Anemonefishes

A complete understanding of how the nervous and endocrine systems interplay within an organism is pivotal for the full characterization of the regulation of its physiological processes, as well as the interaction with its surroundings. These topics are now of major interest in the context of the existing threats linked with global change. In this chapter, we review the current knowledge regarding how anemonefishes respond and acclimate to environmental cues at the morphological, physiological, and behavioural levels. We focus on two natural life history events, metamorphosis and protandrous (male-to-female) sex change, both reflecting the extraordinary phenotypic plasticity of Amphiprioninae, and the potential ways in which the stress axis could mediate these transformations. Additionally, we highlight existing research on the consequences of ocean warming and acidification on these valuable teleost fishes. Finally, we synthesize the scarce data available to date in anemonefishes, an emerging biological model, together with knowledge acquired in this field using canonical fish species (e.g., zebrafish, medaka) or species of economic importance (e.g., salmonids, sea bass)

The Timing of Timezyme Diversification in Vertebrates

International audienceAll biological functions in vertebrates are synchronized with daily and seasonal changes in the environment by the time keeping hormone melatonin. Its nocturnal surge is primarily due to the rhythmic activity of the arylalkylamine N-acetyl transferase AANAT, which thus became the focus of many investigations regarding its evolution and function. Various vertebrate isoforms have been reported from cartilaginous fish to mammals but their origin has not been clearly established. Using phylogeny and synteny, we took advantage of the increasing number of available genomes in order to test whether the various rounds of vertebrate whole genome duplications were responsible for the diversification of AANAT. We highlight a gene secondary loss of the AANAT2 in the Sarcopterygii, revealing for the first time that the AAANAT1/2 duplication occurred before the divergence between Actinopterygii (bony fish) and Sarcopterygii (tetrapods, lobe-finned fish, and lungfish). We hypothesize the teleost-specific whole genome duplication (WDG) generated the appearance of the AANAT1a/1b and the AANAT2/ 29paralogs, the 29 isoform being rapidly lost in the teleost common ancestor (ray-finned fish). We also demonstrate the secondary loss of the AANAT1a in a Paracantopterygii (Atlantic cod) and of the 1b in some Ostariophysi (zebrafish and cave fish). Salmonids present an even more diverse set of AANATs that may be due to their specific WGD followed by secondary losses. We propose that vertebrate AANAT diversity resulted from 3 rounds of WGD followed by previously uncharacterized secondary losses. Extant isoforms show subfunctionalized localizations, enzyme activities and affinities that have increased with time since their emergence

Mélatonine et régulations neuroendocrines chez le poisson

La mélatonine est l'hormone donneuse de temps chez les Vertébrés. Par son rythme de sécrétion journalier et saisonnier elle contribue à la synchronisation de comportements et de régulations physiologiques sur les périodicités naturelles. La conservation et la diversité caractérisent le système mélatoninergique chez les Poissons chez les Vertébrés : conservation car le mode de production de la mélatonine et les propriétés de synchronisation sont une constante ; diversité car la régulation de la synthèse et les modes d'action ont été profondément modifiés au cours de l'évolution. Cette revue résume nos connaissances actuelles sur les cibles et les modes d'action de la mélatonine et des parallèles sont faits avec les Mammifères

Contrôle photopériodique de la synthèse de mélatonine par la rétine et l'épiphyse de poisson

La mélatonine est l'hormone donneuse de temps chez les Vertébrés. Par la dynamique de sa production nycthémérale et saisonnière, elle assure la synchronisation de fonctions physiologiques et de comportements sur des périodicités naturelles. Chez les poissons, la mélatonine est synthétisée principalement par les cellules photoréceptrices de l'organe pinéal et de la rétine. La voie de synthèse de la mélatonine est également activée au niveau de certains types cellulaires des couches "nucléaire interne" et "ganglionnaire" de la rétine. Chez une majorité d'espèces, la synthèse de mélatonine est maximale de nuit (high-at-night ), assujettie aux variations circadiennes de l'avant-dernière enzyme de la voie de sa synthèse, l'arylalkylamine N-acétyltranférase (AANAT). Chez d'autres, le profil de mélatonine rétinienne présente un maximum le jour (high-at-day ), ou aux interphases. Les données de la littérature résumées ici concernent les mécanismes moléculaires et cellulaires mis en jeu dans le contrôle de la production de cet important messager du système circadien, soulignant en particulier leur plasticité

Generation and characterization of the sea bass Dicentrarchus labrax brain and liver transcriptomes.

International audienceThe sea bass Dicentrarchus labrax is the center of interest of an increasing number of basic or applied research investigations, even though few genomic or transcriptomic data is available. Current public data only represent a very partial view of its transcriptome. To fill this need, we characterized brain and liver transcriptomes in a generalist manner that would benefit the entire scientific community. We also tackled some bioinformatics questions, related to the effect of RNA fragment size on the assembly quality. Using Illumina RNA-seq, we sequenced organ pools from both wild and farmed Atlantic and Mediterranean fishes. We built two distinct cDNA libraries per organ that only differed by the length of the selected mRNA fragments. Efficiency of assemblies performed on either or both fragments size differed depending on the organ, but remained very close reflecting the quality of the technical replication. We generated more than 19,538Mbp of data. Over 193million reads were assembled into 35,073 contigs (average length=2374bp; N50=3257). 59% contigs were annotated with SwissProt, which corresponded to 12,517 unique genes. We compared the Gene Ontology (GO) contig distribution between the sea bass and the tilapia. We also looked for brain and liver GO specific signatures as well as KEGG pathway coverage. 23,050 putative micro-satellites and 134,890 putative SNPs were identified. Our sampling strategy and assembly pipeline provided a reliable and broad reference transcriptome for the sea bass. It constitutes an indisputable quantitative and qualitative improvement of the public data, as it provides 5 times more base pairs with fewer and longer contigs. Both organs present unique signatures consistent with their specific physiological functions. The discrepancy in fragment size effect on assembly quality between organs lies in their difference in complexity and thus does not allow prescribing any general strategy. This information on two key organs will facilitate further functional approaches

Devenir et effets de polluants organiques persistants (PCB, PBDE) sur la reproduction des poissons, le développement et la survie de la descendance - Fish'N'POPs

Parmi les polluants organiques persistants, les PCB (polychlorobiphényles) bien qu’interdits depuisplusieurs décennies, et les PBDE (polybromodiphényléthers) dʹusage plus récent et considérés commedes polluants émergents, sont présents de façon ubiquiste dans lʹenvironnement sous forme demélanges de différents congénères dont les proportions relatives dépendent de leurs sources et de leurdevenir, incluant leur dégradation. FishʹnʹPOPs avait deux objectifs : 1) Mesurer les effets à long termechez les poissons dʹune exposition par voie alimentaire à ces polluants en mélanges (PCB et/ou PBDE)pertinents sur le plan environnemental en étudiant i) les fonctions impactant le recrutement(reproduction et survie de la descendance) ; ii) le devenir de ces polluants, leurs interactions avec leslipides et les mécanismes gouvernant la distribution des polluants dans lʹorganisme; iii) le transfertvers les oeufs et les effets sur plusieurs générations en utilisant la modélisation énergétique, dedynamique des populations et de l’évolution des traits biologiques. 2) Comprendre les mécanismesd’action moléculaires sous‐jacents et développer de nouveaux biomarqueurs d’effets

Devenir et effets de polluants organiques persistants (PCB, PBDE) sur la reproduction des poissons, le développement et la survie de la descendance

Parmi les polluants organiques persistants, les PCB (polychlorobiphényles) bien qu’interdits depuisplusieurs décennies, et les PBDE (polybromodiphényléthers) dʹusage plus récent et considérés commedes polluants émergents, sont présents de façon ubiquiste dans lʹenvironnement sous forme demélanges de différents congénères dont les proportions relatives dépendent de leurs sources et de leurdevenir, incluant leur dégradation. FishʹnʹPOPs avait deux objectifs : 1) Mesurer les effets à long termechez les poissons dʹune exposition par voie alimentaire à ces polluants en mélanges (PCB et/ou PBDE)pertinents sur le plan environnemental en étudiant i) les fonctions impactant le recrutement(reproduction et survie de la descendance) ; ii) le devenir de ces polluants, leurs interactions avec leslipides et les mécanismes gouvernant la distribution des polluants dans lʹorganisme; iii) le transfertvers les oeufs et les effets sur plusieurs générations en utilisant la modélisation énergétique, dedynamique des populations et de l’évolution des traits biologiques. 2) Comprendre les mécanismesd’action moléculaires sous‐jacents et développer de nouveaux biomarqueurs d’effets