Repository logo
 
Loading...
Project Logo
Research Project

MOLECULAR AND CELLULAR EFFECTS OF IOXINIL AND DIETHYLSTILBESTROL ON ZEBRAFISH THYROCYTE DEVELOPMENT AND ADULT HOMEOSTASIS

Authors

Publications

Vasotocin and isotocin regulate aquaporin 1 function in the sea bream
Publication . Martos-Sitcha, Juan Antonio; Campinho, Marco António; Miguel Mancera, Juan; Martinez-Rodriguez, Gonzalo; Fuentes, Juan
Aquaporins (AQPs) are specific transmembrane water channels with an important function in water homeostasis. In terrestrial vertebrates, AQP2 function is regulated by vasopressin (AVP) to accomplish key functions in osmoregulation. The endocrine control of aquaporin function in teleosts remains little studied. Therefore, in this study we investigated the regulatory role of vasotocin (AVTR) and isotocin (ITR) receptors in Aqp1 paralog gene function in the teleost gilthead sea bream (Sparus aurata). The complete coding regions of Aqp1a, Aqp1b, AVTR V1a2-type, AVTR V2-type and ITR from sea bream were isolated. A Xenopus oocyte-swelling assay was used to functionally characterize AQP1 function and regulation by AVT and IT through their cognate receptors. Microinjection of oocytes with Aqp1b mRNA revealed regulation of water transport via PKA (IBMX+forskolin sensitive), whereas Aqp1a mRNA injection had the same effect via PKC signaling (PDBU sensitive). In the absence of expressed receptors, AVT and IT (10(-8) mol l(-1)) were unable to modify AQP1 function. AVT regulated AQP1a and AQP1b function only when the AVTR V2-type was co-expressed. IT regulated AQP1a function, but not AQP1b, only when ITR was present. Considering that Aqp1a and Aqp1b gene expression in the sea bream intestine is highly salinity dependent in vivo, our results in ovo demonstrate a regulatory role for AVT and IT in AQP1 function in the sea bream in the processing of intestinal fluid to achieve osmoregulation.
A thyroid hormone regulated asymmetric responsive centre is correlated with eye migration during flatfish metamorphosis
Publication . Campinho, Marco António; Silva, Nádia; Martins, Gabriel G.; Anjos, Liliana; Florindo, Claudia; Roman-Padilla, Javier; Garcia-Cegarra, Ana; Louro, Bruno; Manchado, Manuel; Power, Deborah
Flatfish metamorphosis is a unique post-embryonic developmental event in which thyroid hormones (THs) drive the development of symmetric pelagic larva into asymmetric benthic juveniles. One of the eyes migrates to join the other eye on the opposite side of the head. Developmental mechanisms at the basis of the acquisition of flatfish anatomical asymmetry remain an open question. Here we demonstrate that an TH responsive asymmetric centre, determined by deiodinase 2 expression, ventrally juxtaposed to the migrating eye in sole (Solea senegalensis) correlates with asymmetric cranial ossification that in turn drives eye migration. Besides skin pigmentation that is asymmetric between dorsal and ventral sides, only the most anterior head region delimited by the eyes becomes asymmetric whereas the remainder of the head and organs therein stay symmetric. Sub-ocular ossification is common to all flatfish analysed to date, so we propose that this newly discovered mechanism is universal and is associated with eye migration in all flatfish.
Olfactory-like neurons are present in the forehead of common cuttlefish, Sepia officinalis Linnaeus, 1758 (Cephalopoda: Sepiidae)
Publication . Campinho, Marco António; Oliveira, Ana R.; Sykes, António V.
According to the literature, the cuttlefish, Sepia officinalis, possesses a specialized olfactory organ and cells, located in olfactory ventral pits. In this study, the location of olfactory receptor neurons (ORNs) at the cellular level was determined using cellular morphology and immunohistochemistry. An antiserum against PBP3 was used as a marker to identify ORN-like cells in cuttlefish after validation for specificity to cephalopod ORN cells in the common octopus, Octopus vulgaris. The results show that ORN-like cells in S. officinalis were not found in the ventral pits, suckers or the mouth lips. Instead, ORN-like cells were found scattered in the forehead, between the eyes. The absence of ORNlike cells in a pit in S. officinalis and the sharing of four similar types of ORN cells with the squid and octopus lineages suggest that this might be a later innovation in olfaction and is probably associated with the specialized lifestyle of these later evolved cephalopods. Together, this evidence suggests a diversification of ORN cell types in Coleoidea, which did not occur in Nautiloidea, which might have preceded the diversification of the Coleoidea.
Maternal thyroid hormones are essential for neural development in Zebrafish
Publication . Campinho, Marco António; Saraiva, João; Florindo, Claudia; Power, Deborah M.
Teleost eggs contain an abundant store of maternal thyroid hormones (THs), and early in zebrafish embryonic development, all the genes necessary for TH signaling are expressed. Nonetheless the function of THs in embryonic development remains elusive. To test the hypothesis that THs are fundamental for zebrafish embryonic development, an monocarboxilic transporter 8 (Mct8) knockdown strategy was deployed to prevent maternal TH uptake. Absence of maternal THs did not affect early specification of the neural epithelia but profoundly modified later dorsal specification of the brain and spinal cord as well as specific neuron differentiation. Maternal THs acted upstream of pax2a, pax7, and pax8 genes but downstream of shha and fgf8a signaling. The lack of inhibitory spinal cord interneurons and increased motoneurons in the mct8 morphants is consistent with their stiff axial body and impaired mobility. The mct8 mutations are associated with X-linked mental retardation in humans, and the cellular and molecular consequences of MCT8 knockdown during embryonic development in zebrafish provides new insight into the potential role of THs in this condition.
Endocrine regulation of carbonate precipitate formation in marine fish intestine by stanniocalcin and PTHrP
Publication . Gregorio, Silvia F.; Carvalho, Edison S. M.; Campinho, Marco A.; Power, Deborah M.; Canario, Adelino V. M.; Fuentes, Juan
In marine fish, high epithelial bicarbonate secretion by the intestine generates luminal carbonate precipitates of divalent cations that play a key role in water and ion homeostasis. In vitro studies highlight the involvement of the calciotropic hormones PTHrP (parathyroid hormone-related protein) and stanniocalcin (STC) in the regulation of epithelial bicarbonate transport. The present study tested the hypothesis that calciotropic hormones have a regulatory role in carbonate precipitate formation in vivo. Sea bream (Sparus aurata) juveniles received single intraperitoneal injections of piscine PTHrP(1-34), the PTH/PTHrP receptor antagonist PTHrP(7-34) or purified sea bream STC, or were passively immunized with polyclonal rabbit antisera raised against sea bream STC (STC-Ab). Endocrine effects on the expression of the basolateral sodium bicarbonate cotransporter (Slc4a4.A), the apical anion exchangers Slc26a6.A and Slc26a3.B, and the V-type proton pump beta-subunit (Atp6v1b) in the anterior intestine were evaluated. In keeping with their calciotropic nature, the hypocalcaemic factors PTHrP(7-34) and STC upregulated gene expression of all transporters. In contrast, the hypercalcaemic factor PTHrP(1-34) and STC antibodies downregulated transporters involved in the bicarbonate secretion cascade. Changes in intestine luminal precipitate contents provoked by calcaemic endocrine factors validated these results: 24 h postinjection either PTHrP(1-34) or immunization with STC-Ab reduced the carbonate precipitate content in the sea bream intestine. In contrast, the PTH/PTHrP receptor antagonist PTHrP(7-34) increased not only the precipitated fraction but also the concentration of HCO3 equivalents in the intestinal fluid. These results confirm the hypothesis that calciotropic hormones have a regulatory role in carbonate precipitate formation in vivo in the intestine of marine fish. Furthermore, they illustrate for the first time in fish the counteracting effect of PTHrP and STC, and reveal an unexpected contribution of calcaemic factors to acid-base balance.

Organizational Units

Description

Keywords

Contributors

Funders

Funding agency

Fundação para a Ciência e a Tecnologia

Funding programme

Funding Award Number

SFRH/BPD/66808/2009

ID