Browsing by Author "Martins, Gil Sales Marques"
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- Establishing zebrafish nutritional requirements in phospholipids, minerals and vitamins: effects on growth and skeletal developmentPublication . Martins, Gil Sales Marques; Gavaia, Paulo J.; Dias, Jorge ProençaZebrafish (Danio rerio) is considered a cost-effective model species adequate for research, due to easy maintenance and breeding. Nowadays the use of this species is increasing mainly due to the information coming from genome sequencing, known target genes, and technology for gene knock–down and manipulation. However, the nutrition of zebrafish is poorly studied, with the fish being fed with variable sources of artemia nauplii and commercial diets, which cause effects in research results. The necessity for an adequate balanced diet is a need for scientific replication and animal welfare. The aim of this study was to evaluate the effect of nutritional modulation by supplementing purified diets in vitamins (vitamin D3), phospholipids (phosphatidylethanolamine - PE and phosphatidylcoline - PC) and trace minerals (selenium, zinc, manganese and iodine) in zebrafish growth and reproductive success and subsequently in the larval growth, survival and skeletal development. The experiment was performed with groups of 8 adult zebrafish (5 females and 3 males) per dietary treatment, which were fed with each experimental diet during 28 days before being mated. As results it was observed that control diet (CD) had a positive effect on breeder’s growth and weight, but without success in reproduction. The vitamin D3 - cholecalciferol (D3) presented the lowest growth in adult’s weight, and the lowest TM. The PC diet caused an increment in adult length and an increase in egg diameter and perivitelline space, but with a negative effect in larvae length. The increment in PE on diet of adult zebrafish improved sperm total (TM) and progressive motility (PM), egg diameter and led to an increase of perivitelline space, but with poor results in larvae length. The zinc (ZN) diet caused an increment in initial larval growth (5dpf) and total mineral deposition. The increment of iodine (I) on diet led to a good larvae growth in length (28 dpf), but presented lower values in of egg diameter, perivitelline space. This treatment, despite the poor indicators of egg quality, induced a higher larval growth and a higher mineral content.
- The influence of inflammatory processes in fish skeletal development: the crosstalk between skeletal and immune systemsPublication . Martins, Gil Sales Marques; Gavaia, Paulo Jorge Travessa; Abellán, Francisco António GuardiolaOsteoimmunology is an emerging field focused on the comprehension of the crosstalk between the immune and skeletal systems, with a particular focus on how inflammation affects bone health and disease. Previous research suggests that the same signalling mechanism that occurs in mammals may trigger the differentiation of macrophages into osteoclasts in teleosts, leading to the onset of pathological bone resorption by an identical molecular process. However, little is known about the contribution of the inflammatory processes and or bacterial constituents in fish bone tissues. In this thesis, we tackle this issue by evaluating the impact of continuous exposure to bacterial lipopolysaccharides (LPS) in zebrafish dermal skeleton (scales) and evaluating the potential of the microalga Tisochrysis lutea ethanolic extract and its glycolipid (GL) fractions to reverse the LPS effects. The continuous exposure to LPS led to the reduction of de novo formed scales and led to scale demineralization, with increased osteoclast activity, and inflammatory and osteoclastic marker genes (i.e., tnfa, ctsk, and acp5). In ex vivo cultured scales, LPS led to an increase in the number of osteoclast areas, while reducing the number of macrophages. An overlap between cell types and TRAP+ signals indicates the possible differentiation of macrophages into osteoclasts. T. lutea extract and two isolated glycolipid fractions (Tl-glF1 and Tl-glF2) evidenced an anti-osteoclastic potential against the differentiation of RAW 264.7-derived osteoclasts (RAW-Ocs), with a reduced number of mono- and multinucleated osteoclasts. The data collected in this thesis supports the use of zebrafish scales exposed to LPS at 10 μg mL-1 as an in vivo and ex vivo screening method for searching novel anti-resorptive compounds for inflammatory diseases, to study the mechanisms involved in increased bone resorption, and the role of LPS in the differentiation of macrophages into osteoclasts. T. lutea GLs contain anti-resorptive properties and should be further investigated for their application in osteoimmune diseases.