Differential involvement of the three nuclear estrogen receptors during oogenesis in European sea bass (Dicentrarchus labrax)†.

Estrogens are involved in a wide range of processes in vertebrate reproduction through ligand activation of their specific cognate receptors. In most teleosts, three nuclear estrogen receptor subtypes have been identified (Esr1, Esr2a, and Esr2b). Differences in ligand binding affinity and seasonal expression patterns in reproductive tissues among these Esr subtypes suggest distinct roles during oogenesis, vitellogenesis, and spermatogenesis.

Gonadotropins in European sea bass: Endocrine roles and biotechnological applications.

Follicle stimulating hormone (Fsh) and luteinizing hormone (Lh) are central endocrine regulators of the gonadal function in vertebrates. They act through specific receptors located in certain cell types found in the gonads. In fish, the differential roles of these hormones are being progressively elucidated due to the development of suitable tools for their study.

Toll-like receptor 22 of gilthead seabream, Sparus aurata: molecular cloning, expression profiles and post-transcriptional regulation.

TLR22 is a fish-specific TLR that recognizes dsRNAs. In the present study, a TLR22 homologue gene from gilthead seabream (sbTLR22) was identified and characterized. The full coding sequence contained a single open-reading frame of 2895 nucleotides encoding a predicted protein of 964 amino acids in length.

Recombinant TNFα as oral vaccine adjuvant protects European sea bass against vibriosis: insights into the role of the CCL25/CCR9 axis.

Vibrio anguillarum is the main causative agent of vibriosis in cultured sea bass. Unfortunately, available vaccines against this disease do not achieve the desired protection. In this study, to accomplish uptake, processing, and presentation of luminal antigens, a commercial sea bass oral vaccine against V.

Molecular cloning, phylogenetic analysis and functional characterization of soluble Toll-like receptor 5 in gilthead seabream, Sparus aurata.

Two forms of TLR5, one membrane-anchored and one soluble, have been described in some teleost fish species. However, the exact role of each form has been poorly studied. In the present study, we show that the mRNA levels of soluble gilthead seabream TLR5 (sbTLR5S) are highly induced in head kidney, spleen, liver and blood after Vibrio anguillarum infection, suggesting an important role for sbTLR5S in the innate immune response against bacteria.

Luteinizing hormone plasmid therapy results in long-lasting high circulating Lh and increased sperm production in European sea bass (Dicentrarchus labrax).

The present work aimed at evaluating the potential of intramuscular injection of a hormone-coding gene as an approach for gene therapy in fish. A plasmid containing luteinizing hormone (Lh) in a single-chain (sc) form, pCMV-scLh, was chosen as the coding gene, and sea bass was chosen as the target species. In vivo injection of pCMV-scLh in muscle of juvenile sea bass rendered plasma Lh levels higher than 50 ng/ml in 40% of the injected fish, while these Lh levels were only detected in 4% of controls.

Receptor specificity and functional comparison of recombinant sea bass (Dicentrarchus labrax) gonadotropins (FSH and LH) produced in different host systems.

Different yields, biopotency, and in vivo pharmacokinetics are obtained for recombinant sea bass gonadoltropins depending on the production system and DNA construct, but they show specific activation of their corresponding receptors. Gonadotropins (GTHs) are glycoprotein hormones that play a major role in the regulation of gonadal functions. Recently, we succeeded in isolating the native sea bass Fsh from sea bass pituitaries, but to ensure the availability of bioactive GTHs and no cross-contamination with other related glycoproteins, recombinant sea bass GTHs were produced using two expression systems-insect and mammalian cells-and different constructs that yielded tethered or noncovalently bound dimers.

Molecular strategies used by fish pathogens to interfere with host-programmed cell death.

Cell death is of pivotal importance in the regulation of the immune response and has a direct impact in disease resistance. Fish are becoming an interesting model organism to study the immune response since they hold a key phylogenetic position and many species are of high economic interest. The role of cell death in the immune response has recently been investigated in fish and the molecules and pathways orchestrating cell death in this group of animals have begun to be elucidated.

Cloning, expression and functional characterization of chicken CCR6 and its ligand CCL20.

Chemokines are key molecules that drive migration of lymphoid and myeloid cells toward organs in basal as well as inflammatory conditions. By recruiting immature dendritic cells to the mucosal surfaces, CCL20 acts in the very early events leading to the development of a specific immune response. In order to characterize dendritic cells in birds and better understand their role in the initiation of immune responses against pathogens of economic as well as human health relevance, we have cloned and expressed chicken CCL20 (chCCL20) and its specific receptor chCCR6.

Regulation of exogenous gene expression in fish cells: an evaluation of different versions of the tetracycline-regulated system.

The exogenous control of foreign gene expression is relevant to both basic research and biotechnological applications. In fish, the number of isolated genes has become larger in the last few years; however an efficient system for controlling gene expression is not yet available. The tetracycline-regulated system has proved to be efficient and it is widely used in mammals, but it has never been tested in fish.

A one-step approach to obtain cell clones expressing tetracycline-responsive transactivators.

Despite the wide application of the tetracycline-regulated gene expression system, several drawbacks in establishing the system in in vitro-cultured cells have been described. Most of the problems are related to obtaining a reliable tetracycline-regulated cell clone, which often results in arduous labor. We describe here a new approach to facilitate the screening and selection of such cell clones.