The influence of inflammatory processes in fish skeletal development: the crosstalk between skeletal and immune systems

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Type I Diabetes in Zebrafish reduces sperm quality and increases Insulin and Glucose transporter transcripts

Publication . Diogo, Patricia; Martins, Gil; F. Simao, Marcio; Marreiros, Ana; Eufrásio, Ana Catarina; Cabrita, Elsa; J. Gavaia, Paulo

Type I diabetes is a prominent human pathology with increasing incidence in the population; however, its cause is still unknown. This disease promotes detrimental effects on reproduction, such as lower sperm motility and DNA integrity. Hence, the investigation of the underlying mechanisms of this metabolic disturbance in reproduction and its transgenerational consequences is of the utmost importance. The zebrafish is a useful model for this research considering its high homology with human genes as well as its fast generation and regeneration abilities. Therefore, we aimed to investigate sperm quality and genes relevant to diabetes in the spermatozoa of Tg(ins:nfsb-mCherry) zebrafish, a model for type I diabetes. Diabetic Tg(ins:nfsb-mCherry) males showed significantly higher expression of transcripts for insulin a (insa) and glucose transporter (slc2a2) compared to controls. Sperm obtained from the same treatment group showed significantly lower sperm motility, plasma membrane viability, and DNA integrity compared to that from the control group. Upon sperm cryopreservation, sperm freezability was reduced, which could be a consequence of poor initial sperm quality. Altogether, the data showed similar detrimental effects related to type I diabetes in zebrafish spermatozoa at the cellular and molecular levels. Therefore, our study validates the zebrafish model for type I diabetes research in germ cells.

2023-04-11Journal article

Open access

Comparison of different microalgae biomass typologies used in rotifers enrichment for zebrafish (Danio rerio) larvae nutrition

Publication . de Castro, Daniela; Castaldi, Matthew; Martins, Gil; Santos, Tamara; Pereira, Hugo; Diogo, Patrícia; Varela, João; Gavaia, Paulo; Shivendra Kumar

The use of enriched rotifers with industrially produced microalgae represents a valuable tool for the enhancement of zebraﬁshlarval nutrition and increased biological performance. Currently, a monoculture of microalgal species (Nannochloropsis sp.) inform of liquid paste is routinely used for rotifers enrichment for zebraﬁsh larvae feeding; however, the most adequate typology (i.e.,paste or freeze-dried) of the industrially produced microalgal biomass is still controversial. This work aimed to compare the effectsof rotifers enriched with three different industrially produced microalgae species (i.e., Nannochloropsis oceanica, Tetraselmis chui,and Tisochrysis lutea) using paste and freeze-dried powder. Enriched rotifers were provided as feed during larval growth and theimpact on growth and survival was evaluated. The use of enriched rotifers with both paste or freeze-dried microalgae improvedgrowth compared to larvae fed exclusively with commercial microdiet. Larvae fed rotifers enriched with N. oceanica and T. chuiattained higher weight and length both at 15 and 30 days postfertilization (dpf ), while the use of microalgae in paste contributed togreater larvae lengths when compared to freeze-dried. The experimental results in this study revealed that N. oceanica and T. chuiin paste are the most suitable microalgae forms to be used in zebraﬁsh larvae nutrition and in the improvement of enrichmentmethodologies for rotifers.

2025-01Journal article

Open access

The influence of inflammatory processes in fish skeletal development: the crosstalk between skeletal and immune systems

Publication . Martins, Gil Sales Marques; Gavaia, Paulo Jorge Travessa; Abellán, Francisco António Guardiola

Osteoimmunology 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.

2025-07-04Doctoral thesis

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