foxe1 mutant zebrafish show indications of a hypothyroid phenotype and increased sensitivity to ethanol for craniofacial malformations.

Background: FOXE1 mutations in humans are associated with cleft palate and hypothyroidism. We previously developed a foxe1 mutant zebrafish demonstrating mineralization defects in larvae. In the present study, we investigate the thyroid status and skeletal phenotype of adult foxe1 mutants.

Certainty-based marking in a formative assessment improves student course appreciation but not summative examination scores.

Background: Study motivation and knowledge retention benefit from regular student self-assessments. Inclusion of certainty-based learning (CBL) in computer-assisted formative tests may further enhance this by enabling students to identify whether they are uninformed or misinformed regarding the topics tested, which may trigger future study actions including instructor consultation.

Methods: Using a cross-over study design involving two out of thirteen computer-assisted formative assessments (CAFAs) of a first-year cell biology course, we compared student-instructor interactions, student learning experiences and final exam scores between two (bio)medical science student cohorts who worked with different CBL-containing CAFAs.

Transepithelial transfer of phenanthrene, but not of benzo[a]pyrene, is inhibited by fatty acids in the proximal intestine of rainbow trout (Oncorhynchus mykiss).

The inclusion of vegetable oils in aquafeeds introduces contaminating polycyclic aromatic hydrocarbons (PAHs) in salmonids. Since lipophilic PAHs solubilize in micelles composed of lipids, bile salts and fatty acids, dietary lipid composition can alter intestinal transepithelial PAH transfer. We studied the uptake of two PAHs, viz.

Design of Radioiodinated Pharmaceuticals: Structural Features Affecting Metabolic Stability towards in Vivo Deiodination.

Radioiodinated pharmaceuticals are convenient tracers for clinical and research investigations because of the relatively long half-lives of radioactive iodine isotopes (i.e., I, I, and I) and the ease of their chemical insertion.

The polycyclic aromatic hydrocarbons benzo[a]pyrene and phenanthrene inhibit intestinal lipase activity in rainbow trout (Oncorhynchus mykiss).

Elevated levels of polycyclic aromatic hydrocarbons (PAHs) are detected in aquafeeds where fish oils are (partially) replaced by vegetable oils. The highly lipophilic PAHs solubilize readily in oil droplets and micelles in the intestinal lumen that can affect enzymatic lipid digestion by altering lipase activity. We therefore investigated the effect of two PAHs, benzo[a]pyrene (BaP) and phenanthrene (PHE), on bile salt-activated lipase (BAL) activity in desalted luminal extracts of the proximal intestine of rainbow trout (Oncorhynchus mykiss) using the triacylglycerides rapeseed oil and fish oil as substrates.

Uptake of benzo[a]pyrene, but not of phenanthrene, is inhibited by fatty acids in intestinal brush border membrane vesicles of rainbow trout (Oncorhynchus mykiss).

Partial replacement of fish ingredients with vegetable ingredients has elevated levels of polycyclic aromatic hydrocarbons (PAHs) in Atlantic salmon reared on these feeds. PAH uptake in the intestinal tract is postulated to occur in association with lipid absorption and could well be affected by fatty acid composition. We therefore investigated the effects of a fish oil and vegetable oil fatty acid, eicosapentaenoic acid (EPA; 20:5n-3) and oleic acid (18:1n-9) respectively, on the uptake of benzo[a]pyrene (BaP) and phenanthrene (PHE) across the intestinal brush border membrane in the salmonid species rainbow trout (Oncorhynchus mykiss).

Triclosan exposure results in alterations of thyroid hormone status and retarded early development and metamorphosis in Cyprinodon variegatus.

Thyroid hormones are critically involved in somatic growth, development and metamorphosis of vertebrates. The structural similarity between thyroid hormones and triclosan, an antimicrobial compound widely employed in consumer personal care products, suggests triclosan can have adverse effects on the thyroid system. The sheepshead minnow, Cyprinodon variegatus, is now used in ecotoxicological studies that have recently begun to focus on potential disruption of the thyroid axis by endocrine disrupting compounds.

The teleost head kidney: Integrating thyroid and immune signalling.

The head kidney, analogous to the mammalian adrenal gland, is an organ unique for teleost fish. It comprises cytokine-producing lymphoid cells from the immune system and endocrine cells secreting cortisol, catecholamines, and thyroid hormones. The intimate organization of the immune system and endocrine system in one single organ makes bidirectional signalling between these possible.

Branchial nitrogen cycle symbionts can remove ammonia in fish gills.

Knowledge of the mechanisms by which fish excrete their metabolic nitrogenous waste and insights into nitrogen cycling in aquaculture systems is of utmost importance to improve the sustainable commercial production of fish. In fish, most nitrogenous waste is excreted via the gills as ammonia, a potentially toxic nitrogenous compound. In this study; activity assays, physiological experiments, molecular analysis and microscopy were used to show that the gills of fish harbor a unique combination of hitherto overlooked nitrogen-cycle microorganisms that can theoretically detoxify excreted ammonia by converting it into inert dinitrogen gas.

The effect of dietary lipid composition on the intestinal uptake and tissue distribution of benzo[a]pyrene and phenanthrene in Atlantic salmon (Salmo salar).

Uptake of polycyclic aromatic hydrocarbons (PAHs) across the intestine is suggested to occur in association with dietary lipids. Partial replacement of fish ingredients by vegetable ingredients in aquafeeds has led to increased levels of PAHs in marine farmed fish. We therefore investigated, intestinal uptake, tissue distribution and PAH metabolism after a single dose of (14)C-benzo[a]pyrene (BaP) or (14)C-phenanthrene (PHE) given to Atlantic salmon (Salmo salar) acclimatized to a fish oil or vegetable oil based diet.

The thyroid gland and thyroid hormones in sheepshead minnow (Cyprinodon variegatus) during early development and metamorphosis.

The sheepshead minnow is widely used in ecotoxicological studies that only recently have begun to focus on disruption of the thyroid axis by xenobiotics and endocrine disrupting compounds. However, reference levels of the thyroid prohormone thyroxine (T4) and biologically active hormone 3,5,3'-triiodothyronine (T3) and their developmental patterns are unknown. This study set out to describe the ontogeny and morphology of the thyroid gland in sheepshead minnow, and to correlate these with whole-body concentrations of thyroid hormones during early development and metamorphosis.

Energy metabolism of hyperthyroid gilthead sea bream Sparus aurata L.

Thyroid hormones, in particular 3,5,3'-triiodothyronine or T3, are involved in multiple physiological processes in mammals such as protein, fat and carbohydrate metabolism. However, the metabolic actions of T3 in fish are still not fully elucidated. We therefore tested the effects of T3 on Sparus aurata energy metabolism and osmoregulatory system, a hyperthyroid-induced model that was chosen.

Knockdown of monocarboxylate transporter 8 (mct8) disturbs brain development and locomotion in zebrafish.

Allan-Herndon-Dudley syndrome (AHDS) is an inherited disorder of brain development characterized by severe psychomotor retardation. This X-linked disease is caused by mutations in the monocarboxylate transporter 8 (MCT8), an important thyroid hormone transporter in brain neurons. MCT8-knockout mice lack the 2 major neurological symptoms of AHDS, namely locomotor problems and cognitive impairment.

Voluntary timing of food intake increases weight gain and reduces basal plasma cortisol levels in common carp (Cyprinus carpio L.).

We investigated the effect of timing of food intake on growth in common carp (Cyprinus carpio L.). Juvenile carp were demand-fed for 22 days using a computerized pendulum feeder that registered meal requests.

Food deprivation induces chronic stress and affects thyroid hormone metabolism in Senegalese sole (Solea senegalensis) post-larvae.

In vertebrates, stress and thyroid systems interact closely, most likely because of the involvement of both systems in energy metabolism. However, studies on these interactions, especially during larval development, are scarce. Recently, cDNAs coding for corticotropin-releasing hormone (CRH) and CRH-binding protein (CRH-BP), two key players in the regulation of the neuroendocrine stress response, were characterized for the flatfish Senegalese sole (Solea senegalensis).

Kinetics and thiol requirements of iodothyronine 5'-deiodination are tissue-specific in common carp (Cyprinus carpio L.).

Iodothyronine deiodinases determine the biological activity of thyroid hormones. Despite the homology of the catalytic sites of mammalian and teleostean deiodinases, in-vitro requirements for the putative thiol co-substrate dithiothreitol (DTT) vary considerably between vertebrate species. To further our insights in the interactions between the deiodinase protein and its substrates: thyroid hormone and DTT, we measured enzymatic iodothyronine 5'-deiodination, Dio1 and Dio2 mRNA expression, and Dio1 affinity probe binding in liver and kidney preparations from a freshwater teleost, the common carp (Cyprinus carpio L.

Environmental factors affecting thyroid function of wild sea bass (Dicentrarchuslabrax) from European coasts.

Thyroid functional status of wild fish in relation with the contamination of their environment deserves further investigation. We here applied a multi-level approach of thyroid function assessment in 87 wild sea bass collected near several estuaries: namely the Scheldt, the Seine, the Loire, the Charente and the Gironde. Thyroxine (T(4)) and triiodothyronine (T(3)) concentrations in muscle were analyzed by radioimmunoassay.

Subfunctionalization of POMC paralogues in Senegalese sole (Solea senegalensis).

The precursor protein proopiomelanocortin (POMC) gives rise to a variety of biologically active peptides through cell-specific posttranslational processing. Two transcripts of pomc were found in the flatfish Solea senegalensis (ssePOMC-A and ssePOMC-B), that most likely represent subfunctionalized paralogues: ssePOMC-A lacks the N-terminal cleavage site for β-MSH, whereas ssePOMC-B cannot yield ACTH and completely lacks the opioid consensus sequence in the β-END region. An analysis of nucleotide substitution rates shows that the POMC-derived peptides possess well-conserved regions under purifying selection, except the β-END derived from POMC-B, which has undergone positive selection.

Anammox bacteria in different compartments of recirculating aquaculture systems.

Strict environmental restrictions force the aquaculture industry to guarantee optimal water quality for fish production in a sustainable manner. The implementation of anammox (anaerobic ammonium oxidation) in biofilters would result in the conversion of both ammonium and nitrite (both toxic to aquatic animals) into harmless dinitrogen gas. Both marine and freshwater aquaculture systems contain populations of anammox bacteria.

Identification and functional characterization of zebrafish solute carrier Slc16a2 (Mct8) as a thyroid hormone membrane transporter.

Most components of the thyroid system in bony fish have been described and characterized, with the notable exception of thyroid hormone membrane transporters. We have cloned, sequenced, and expressed the zebrafish solute carrier Slc16a2 (also named monocarboxylate transporter Mct8) cDNA and established its role as a thyroid hormone transport protein. The cloned cDNA shares 56-57% homology with its mammalian orthologs.

Thyroid dysfunction in sea bass (Dicentrarchus labrax): underlying mechanisms and effects of polychlorinated biphenyls on thyroid hormone physiology and metabolism.

The current study examines the effect of subchronic exposure to a mixture of Aroclor standards on thyroid hormone physiology and metabolism in juvenile sea bass. The contaminant mixture was formulated to reflect the persistent organic pollution to which the European sea bass population could conceivably be exposed (0.3, 0.

Chronic and acute stress responses in Senegalese sole (Solea senegalensis): the involvement of cortisol, CRH and CRH-BP.

The hypothalamus-pituitary-interrenal (HPI) axis is pivotal in the endocrine stress response of fish. Hypothalamic corticotropin-releasing hormone (CRH) initiates the endocrine stress response and stimulates the release of adrenocorticotropic hormone (ACTH) from the pituitary pars distalis, which in turn activates cortisol production and release by the interrenal cells of the head kidney. CRH activity depends on the levels of a specific CRH binding protein (CRH-BP).

Effects of cortisol and thyroid hormone on peripheral outer ring deiodination and osmoregulatory parameters in the Senegalese sole (Solea senegalensis).

The thyroid gland in fish mainly secretes the thyroid prohormone 3,5,3',5'-tetraiodothyronine (T₄), and extrathyroidal outer ring deiodination (ORD) of the prohormone to 3,5,3'-triiodothyronine (T₃) is pivotal in thyroid hormone economy. Despite its importance in thyroid hormone metabolism, factors that regulate ORD are still largely unresolved in fish. In addition, the osmoregulatory role of T₃ is still a controversial issue in teleosts.

Acclimation of to different ambient temperatures: implications for thyroidal status and osmoregulation.

We have investigated the regulation of thyroidal status and osmoregulatory capacities in juveniles from the teleost acclimated to different ambient temperatures. Juveniles, raised in seawater at 19°C, were acclimated for 3 weeks to temperatures of 12, 19 and 26°C. Since our preliminary observations showed that at 12°C feed intake was suppressed, our experimental design controlled for this factor.