Functional biology of thyroid hormones in teleost development

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In a zebrafish biomedical model of human Allan-Herndon-Dudley syndrome impaired MTH signaling leads to decreased neural cell diversity

Publication . Silva, Nadia; Campinho, Marco António

Maternally derived thyroid hormone (T3) is a fundamental factor for vertebrate neurodevelopment. In humans, mutations on the thyroid hormones (TH) exclusive transporter monocarboxylic acid transporter 8 (MCT8) lead to the Allan-Herndon-Dudley syndrome (AHDS). Patients with AHDS present severe underdevelopment of the central nervous system, with profound cognitive and locomotor consequences. Functional impairment of zebrafish T3 exclusive membrane transporter Mct8 phenocopies many symptoms observed in patients with AHDS, thus providing an outstanding animal model to study this human condition. In addition, it was previously shown in the zebrafish mct8 KD model that maternal T3 (MTH) acts as an integrator of different key developmental pathways during zebrafish development. MethodsUsing a zebrafish Mct8 knockdown model, with consequent inhibition of maternal thyroid hormones (MTH) uptake to the target cells, we analyzed genes modulated by MTH by qPCR in a temporal series from the start of segmentation through hatching. Survival (TUNEL) and proliferation (PH3) of neural progenitor cells (dla, her2) were determined, and the cellular distribution of neural MTH-target genes in the spinal cord during development was characterized. In addition, in-vivo live imaging was performed to access NOTCH overexpression action on cell division in this AHDS model. We determined the developmental time window when MTH is required for appropriate CNS development in the zebrafish; MTH is not involved in neuroectoderm specification but is fundamental in the early stages of neurogenesis by promoting the maintenance of specific neural progenitor populations. MTH signaling is required for developing different neural cell types and maintaining spinal cord cytoarchitecture, and modulation of NOTCH signaling in a non-autonomous cell manner is involved in this process. DiscussionThe findings show that MTH allows the enrichment of neural progenitor pools, regulating the cell diversity output observed by the end of embryogenesis and that Mct8 impairment restricts CNS development. This work contributes to the understanding of the cellular mechanisms underlying human AHDS.

2023Journal article

Open Access

Photoperiod and dietary treatment in freshwater modulate the short-term intestinal response to seawater in atlantic salmon (salmo salar)

Publication . Gaetano, Pasqualina; Fernandes Duarte, Vilma Vanessa; Striberny, Anja; Hazlerigg, David; Jørgensen, Even H.; Campinho, Marco António; Fuentes, Juan

Stimulation and timing of smoltification are essential for successful Atlantic salmon (Salmo salar) aquaculture. This study investigated intestinal responses during dietary and photoperiod manipulation in freshwater (FW) and after a subsequent seven days residence in seawater (SW). "Small" and "large" Atlantic salmon parr (-40 g and -130 g respectively) were treated in FW for 12 weeks and thereafter transferred to SW for seven days. During the FW phase, fish underwent two different light conditions, 24 L:0D - 24 L ("LL-LL" groups) and 7 L:17D - 24 L ("SP-LL" groups) or fed with either regular feed ("LL-LL C" and "SP-LL C" groups) or feed enriched with a salt mix plus free tryptophan ("LL-LL + diet" and "SP-LL + diet" groups). We analyzed Na+/K+-ATPase (NKA) activity, tissue bioelectrical properties in Ussing chambers, and intestinal fluid composition. The NKA activity showed minor variations in relation to fish size, treatments, or intestinal region (anterior or posterior). Photoperiod modulated epithelial bioelectrical properties (Isc and Rt) of the anterior and posterior intestine, particularly transepithelial resistance (Rt). Pharmacological experiments, targeting apical Na+/K+/2Cl- (NKCC2) and Na+/ Cl (NCC) co-transporters revealed intestinal region-and water salinity-dependent effects. In addition, stimu-lation of the intracellular cAMP with forskolin and IBMX showed intestinal region-, water salinity, and treatment-dependence responses with clear functional specialization of the anterior and posterior intestine. The intestinal fluid composition reflected the ability to process ingested SW and showed little variation in large fish. In sum-mary, our data suggest a better pre-adaptation of the intestine during light-stimulated smoltification (SP-LL groups), and the combination of light and diet might give, in an industrial aquaculture setting, an advantage to smaller, but not larger smolts. Intestinal fluid composition in small fish can be used as an index of intestinal function and may act as a long-term performance proxy in SW Atlantic salmon.

2023Journal article

Open Access

Corrigendum: in a zebrafish biomedical model of human Allan-Herndon-Dudley syndrome impaired MTH signaling leads to decreased neural cell diversity

Publication . Silva, Nadia; Campinho, Marco António

2023Journal article

Open Access

Modulation of intestinal growth and differentiation by photoperiod and dietary treatment during smoltification in Atlantic salmon (Salmo salar, L.)

Publication . Fernandes Duarte, Vilma Vanessa; Gaetano, Pasqualina; Striberny, Anja; Hazlerigg, David; Jørgensen, Even H.; Fuentes, Juan; Campinho, Marco António

Atlantic salmon undergo smoltification, a process that prepares the fish to enter and thrive in seawater (SW). Several physiological changes occur during smolting, especially in osmoregulatory tissues, the gill, the kidney, and the intestine. Here we characterized the effects on intestinal morphogenesis of two different, commonly used smoltification regimes during the end of the freshwater phase, photoperiod and/or the addition of salt and amino acid supplements in the diet. We focused on intestinal morphological differentiation, i.e., external perimeter, absorptive perimeter, tissue thickness, and villi density. In addition, we quantified cell proliferation (PCNA positive) and Na+, K+-ATPase (NKA) and Na+, K+,2Cl- (NKCCs) co-transporters expression and enterocyte apicobasal distribution by immunohistochemistry. These analyses show that the anterior and posterior intestines have different developmental dynamics during smoltification. In both intestinal regions, photoperiod and dietary treatment increased the absorptive perimeter. In addition, diet and photoperiod treatments differentially stimulated NKA protein expression in the anterior intestine. NKCC apical-basolateral expression in the enterocytes increased after SW entry in the anterior and posterior intestines. In conclusion, our results show that, as smoltification progresses, the anterior intestine responds more readily to experimental conditions than the posterior intestine. In our study, photoperiod and dietary treatment seem to enhance the development of the capacity to tolerate SW.

2023Journal article

Restricted

Ioxynil and diethylstilbestrol increase the risks of cardiovascular and thyroid dysfunction in zebrafish

Publication . Li, Yi-Feng; Rodrigues, Joana; Campinho, Marco António

Endocrine disruption results from exposure to chemicals that alter the function of the endocrine system in animals. Chronic 60 days of exposure to a low dose (0.1 mu M) of ioxynil (IOX) or diethylstilbestrol (DES) via food was used to determine the effects of these chemicals on the physiology of the heart and thyroid follicles in juvenile zebrafish. Immunofluorescence analysis and subsequent 3D morphometric analysis of the zebrafish heart revealed that chronic exposure to IOX induced ventricle deformation and significant volume increase (p < 0.001). DES exposure caused a change in ventricle morphology, but volume was unaffected. Alongside, it was found that DES exposure upregulated endothelial related genes (angptl1b, mhc1lia, mybpc2a, ptgir, notch1b and vwf) involved in vascular homeostasis. Both IOX and DES exposure caused a change in thyroid follicle morphology. Notably, in IOX exposed juveniles, thyroid fol-licle hypertrophy was observed; and in DES-exposed fish, an enlarged thyroid field was present. In summary, chronic exposure of juvenile zebrafish to IOX and DES affected the heart and the thyroid. Given that both chemicals are able to change the morphology of the thyroid it indicates that they behave as endocrine disruptive chemicals (EDCs). Heart function dynamically changes thyroid morphology, and function and hence it is likely that the observed cardiac effects of IOX and DES are the source of altered thyroid status in these fish.

2022Journal article

Restricted