Background/Aims: The Mediterranean killifish, Aphanius fasciatus (Valenciennes, 1821), is a small euryhaline and eurytherm cyprinodont. While its ecology and role as a bioindicator are well known, its anatomy remains poorly understood. This study aimed to provide the first detailed description of the digestive tract of A. fasciatus, from the oropharyngeal cavity to the rectum. Methods: An anatomical and morphological approach supported by light microscopy was applied to examine oral, pharyngeal, and intestinal structures in adult specimens. Results: The jaws bear tricuspids incisiform teeth, whereas the pharynx has caniniform teeth. The tongue forms a muscular thickening of the oral floor and aids swallowing. The oropharyngeal tract and esophagus lead to a dilated anterior intestinal region resembling a primitive stomach, with mucosal folds and mucus-secreting epithelium, but lacking gastric glands. This chamber functions mainly for food storage, absorption, and preparation rather than true gastric digestion. The intestine extends to the rectum, showing sexual dimorphism: females have a relaxed anus, males a more toned and folded structure. Conclusions: These findings provide essential baseline information for comparison with other experimental models and reinforce the suitability of A. fasciatus as a reliable model for anatomical and functional studies.

Flavonoids are a diverse group of natural polyphenolic compounds, recognized for their ability to modulate cellular pathways and mitigate the pathological processes of many neurodegenerative diseases. This study investigates the neurotrophic potential of a polyphenolic-rich lemon peel extract (Lpe) in a Zebrafish larvae spinal cord injury (SCI) model. To evaluate its potential effects, embryos were divided into six experimental groups: a baseline control group in which larvae were neither subjected to spinal cord injury nor treated (Ctrl Group); a group with larvae subjected to spinal cord injury at 3 dpf without treatment (SCI Group); a group treated continuously with Lpe (25 µg/mL) from 0 to 5 dpf without injury (Continuous Group); a group treated continuously with Lpe and injured at 3 dpf (Continuous SCI Group); a group treated with Lpe starting at 3 dpf without injury (Curative Group); and finally, a group injured at 3 dpf and treated simultaneously with Lpe (Curative SCI Group). Lpe treatment significantly downregulated proinflammatory cytokines (tnfa, il1b, and xcl8), and modulated the neuroregenerative pathways Wnt/β catenin, and neurotrophic factor Bdnf. Immunohistochemical analysis further revealed Sox2-positive cells localized around the central canal, consistent with activation of ependymal progenitor populations involved in injury-induced repair processes. These findings support the exploration of Lpe for mitigating SCI-induced damage.

Natural compounds are increasingly explored for their ability to modulate multiple molecular pathways involved in inflammation and oxidative stress and for their therapeutic potential. Among these, Opuntia ficus-indica (L.) Mill. has attracted growing interest due to its rich phytochemical profile; however, the biological properties of unripe fruits remain largely unexplored. In this study, a hydroalcoholic extract obtained from unripe O. ficus-indica fruits was characterized for its chemical composition, antioxidant capacity, and concentration-dependent embryotoxic profile and subsequently investigated in a zebrafish model of spinal cord injury (SCI). UHPLC-HRMS/MS analysis identified 14 secondary metabolites, mainly flavonoids and phenylpropanoid acids. Antioxidant activity was confirmed by DPPH and ABTS assays. An embryotoxicity assessment conducted according to OECD Test Guideline 236 revealed no mortality at concentrations below 100 µg mL-1 and an LC50 of 323.59 µg mL-1 at 96 h post-fertilization, allowing the identification of non-toxic concentrations for subsequent in vivo experiments. Based on these results, the extract was tested in a larval zebrafish SCI transection model. Treated larvae showed improved locomotor recovery, particularly under continuous exposure, accompanied by modulation of molecular pathways involved in inflammation, neurotrophic support, and neurogenesis, including reduced pro-inflammatory cytokine expression and increased BDNF and Sonic Hedgehog signaling markers. Overall, these findings expand current knowledge on unripe O. ficus-indica and highlight its potential to modulate molecular pathways involved in SCI-induced damage and repair.

Photophores are light-producing organs found in many fish species living in the mesopelagic, bathypelagic, and abyssal layers of the ocean. They function to attract prey, confuse predators, and communicate with other individuals of the same species. Understanding the structure and function of photophores is crucial to exploring bioluminescence and the ecological adaptations of marine life in deep-sea environments. The present study is the first to investigate the photophore anatomy of the mesopelagic fish Ichthyococcus ovatus (Cocco, 1838), using specimens naturally stranded along the coast of the Strait of Messina. The morphology of the ventral photophores of I. ovatus includes four functional parts: a tank containing photogenic cells, a lens filter, a reflector surrounding the entire organ, and a pigmented layer. An immunohistochemical assay was conducted using anti-nNOS and anti-S100p antibodies. The presence of nNOS/NOS type I immunolabeling the pigmented layer surrounding the photophores and the nerve fibers reaching the lens suggests a potential role of neuronal nitric oxide signaling in modulating light shielding by the pigment sheath, controlling light exposure, and adjusting light focusing though the lens-associated nerves. S100p immunostaining was observed in the nerve fibers reaching the photophores, highlighting its potential involvement in regulating neuronal calcium levels and, consequently, influencing signal transmission to control bioluminescence output. A sensory feedback pathway from the photophore to the CNS is suggested. Within the lens and in the irregularly shaped cells located in the photophore’s lens, S100p immunolabeling could indicate active signaling and differentiation processes. These findings expand our understanding of light-emitting systems in mesopelagic fishes and offer a valuable foundation for future studies on the functional and evolutionary significance of photophores.

This work provides a contribution to the understanding of the structure of the photophores in the mesopelagic fish Chauliodus sloani (family Stomiidae), which occasionally are stranded along the coasts of the Strait of Messina (Central Mediterranean Sea). The analysis was carried out through the study of the structure and ultrastructure of the ventral photophores, and it also includes an immunohistochemical investigation that offers valuable insights into the function of these organs. Studies on photophores help clarify many aspects of the ecology of this species, which represents an important functional link in the marine food web.

Central nervous system disorders represent a heterogeneous set of conditions triggered by genetic alterations, environmental exposures, infections, injuries, and even iatrogenic causes. These conditions impact a significant portion of the global population, posing serious concerns for public health. Even though progress has been made in understanding and treating some of these disorders, many others remain poorly understood, with research still in their early stages. For that, adapted experimental models are essential for deciphering the physiopathology of disorders and developing future therapeutic strategies. Within this context, zebrafish (Danio rerio) has emerged as a valuable model for central nervous system disorders, thanks to its high genetic and neuroanatomical homology with humans, the conservation in different aspects of cellular architecture and blood–brain barrier, and the remarkable regenerative ability of the CNS. This review presents the state of the art on zebrafish models for central nervous system disorders, presenting their potential in comprehending the pathophysiological processes and screening therapeutics.

Ion channels play a crucial role in various physiological processes, yet their functions in the reproductive system remain underexplored. This study investigates the expression and the localization of ASIC2, ASIC4, and PIEZO2 ion channels in the reproductive tracts of prepubertal bitches. Western blotting on samples from eight prepubertal bitches confirmed the presence of these ion channels in ovarian, uterine, and uterine tubes tissues, and validated antibody specificity. Immunohistochemistry revealed that all primordial follicles expressed these ion channels, while only some developing follicles showed immunolabeling. These findings suggest ion channels’ potential involvement in oocyte differentiation and maturation. The localization of these channels in uterine tubes, uterine lining, and glandular epithelium suggests a role in tissue maintenance, oocyte transport, and embryo implantation. Additionally, their expression in the tunica media of reproductive vasculature points to a potential role in vascular regulation. Future studies are needed to elucidate the specific mechanisms underlying the role of these channels in reproductive physiology.

Piezo proteins have been identified as mechanosensitive ion channels involved in mechanotransduction. Several ion channel dysfunctions may be associated with diseases (including deafness and pain); thus, studying them is critical to understand their role in mechanosensitive disorders and to establish new therapeutic strategies. The current study investigated for the first time the expression patterns of Piezo proteins in zebrafish octavolateralis mechanosensory organs. Piezo 1 and 2 were immunoreactive in the sensory epithelia of the lateral line system and the inner ear. Piezo 1 (28.7 ± 1.55 cells) and Piezo 2 (28.8 ± 3.31 cells) immunopositive neuromast cells were identified based on their ultrastructural features, and their overlapping immunoreactivity to the s100p specific marker (28.6 ± 1.62 cells), as sensory cells. These findings are in favor of Piezo proteins’ potential role in sensory cell activation, while their expression on mantle cells reflects their implication in the maintenance and regeneration of the neuromast during cell turnover. In the inner ear, Piezo proteins’ colocalization with BDNF introduces their potential implication in neuronal plasticity and regenerative events, typical of zebrafish mechanosensory epithelia. Assessing these proteins in zebrafish could open up new scenarios for the roles of these important ionic membrane channels, for example in treating impairments of sensory systems.

Specific subpopulations of neurons in nerve and sensory systems must be developed and maintained, and this is accomplished in significant part by neurotrophins (NTs) and the signaling receptors on which they act, called tyrosine protein kinase receptors (Trks). The neurotrophins–tyrosine protein kinase receptors (NTs/Trks) system is involved in sensory organ regulation, including the visual system. An NTs/Trks system alteration is associated with neurodegeneration related to aging and diseases, including retinal pathologies. An emergent model in the field of translational medicine, for instance, in aging study, is the annual killifish belonging to the Nothobranchius genus, thanks to its short lifespan. Members of this genus, such as Nothobranchius guentheri, and humans share a similar retinal stratigraphy. Nevertheless, according to the authors’ knowledge, the occurrence and distribution of the NTs/Trks system in the retina of N. guentheri has never been investigated before. Therefore, the present study aimed to localize neurotrophin BDNF, NGF, and NT-3 and TrkA, TrkB, and TrkC receptors in the N. guentheri retina using the immunofluorescence method. The present investigation demonstrates, for the first time, the occurrence of the NTs/Trks system in N. guentheri retina and, consequently, the potential key role of these proteins in the biology and survival of the retinal cells.

Mycoplasmas are known as the minimalist microorganisms in the microbes’ world. Their minimalist nature makes them highly sensitive to the environmental conditions and limits their ability to survive for extended periods outside their animal host. Nevertheless, there are documented instances of mycoplasma transmission over significant distances and this phenomenon may be linked to relatively unexplored abilities of mycoplasmas, such as their capacity to synthesize biofilm—the predominant mode of bacterial growth in nature. The authors decided to establish a method aimed at inducing the clustering of mycoplasma planktonic cells within a biofilm in vitro and subsequently assess the capacity of certain avian mycoplasmas to synthesize a biofilm. A total of 299 avian mycoplasma isolates were included in the study, encompassing both pathogenic (Mycoplasma gallisepticum, M. synoviae, M. meleagridis, M. iowae) and non-pathogenic species (M. gallinaceum, M. gallinarum, M. iners and M. pullorum). The authors successfully demonstrated the feasibility of inducing avian mycoplasmas to synthetize in vitro a biofilm, which can be visually quantified. The only species that did not produce any biofilm was M. iowae. In general, the pathogenic mycoplasmas produced greater quantities of biofilm compared to the non-pathogenic ones. Furthermore, it was observed that the ability to produce biofilm appeared to vary, both qualitatively and quantitatively, not only among different species but also among isolates of a single species. Future studies will be necessary to determine whether biofilm production plays a pivotal epidemiological role for the pathogenic avian mycoplasmas.

The ion channels Piezo 1 and Piezo 2 have been identified as membrane mechano-proteins. Studying mechanosensitive channels in chemosensory organs could help in understanding the mechanisms by which these channels operate, offering new therapeutic targets for various disorders. This study investigates the expression patterns of Piezo proteins in zebrafish chemosensory organs. For the first time, Piezo protein expression in adult zebrafish chemosensory organs is reported. In the olfactory epithelium, Piezo 1 immunolabels kappe neurons, microvillous cells, and crypt neurons, while Calretinin is expressed in ciliated sensory cells. The lack of overlap between Piezo 1 and Calretinin confirms Piezo 1’s specificity for kappe neurons, microvillous cells, and crypt neurons. Piezo 2 shows intense immunoreactivity in kappe neurons, one-ciliated sensory cells, and multi-ciliated sensory cells, with overlapping Calretinin expression, indicating its olfactory neuron nature. In taste buds, Piezo 1 immunolabels Merkel-like cells at the bases of cutaneous and pharyngeal taste buds and the light and dark cells of cutaneous and oral taste buds. It also marks the dark cells of pharyngeal taste buds and support cells in oral taste buds. Piezo 2 is found in the light and dark cells of cutaneous and oral taste buds and isolated chemosensory cells. These findings provide new insights into the distribution of Piezo channels in zebrafish chemosensory organs, enhancing our understanding of their sensory processing and potential therapeutic applications.

This study evaluates the morpho-functional modifications that characterize meniscal development from neonatal to adult dogs. Even if menisci are recognized as essential structures for the knee joint, poor information is available about their morphogenesis, in particular in dog models. Menisci from a group of Dobermann Pinchers aged 0, 10, 30 days, and 4 years (T0, T10, T30, adult, respectively) were analyzed by SEM, histochemistry (Safranin O and Picro Sirius Red Staining analyzed under a polarized light microscope), immunofluorescences (collagen type I and II), biomechanical (compression) and biochemical analyses (glycosaminoglycans, GAGs, and DNA content). SEM analyses revealed that the T0 meniscus is a bulgy structure that during growth tends to flatten, firstly in the inner zone (T10) and then even in the outer zone (T30), until the achievement of the completely smooth adult final shape. These results were further supported by the histochemistry analyses in which the deposition of GAGs started from T30, and the presence of type I birefringent collagen fibers was observed from T0 to T30, while poorly refringent type III collagen fibers were observed in the adult dogs. Double immunofluorescence analyses also evidenced that the neonatal meniscus contains mainly type I collagen fibers, as well as the T10 meniscus, and demonstrated a more evident regionalization and crimping in the T30 and adult meniscus. Young's elastic modulus of the meniscus in T0 and T10 animals was lower than the T30 animals, and this last group was also lower than adult ones (T0-T10 vs T30 vs adult). Biochemical analysis confirmed that cellularity decreases over time from neonatal to adult (p < 0.01). The same decreasing trend was observed in GAGs deposition. These results may suggest that the postnatal development of canine meniscus may be related to the progressive functional locomotory development: after birth, the meniscus acquires its functionality over time, through movement, load, and growth itself.

The morphology of the oral cavity of fish is related to their feeding habits. In this context, taste buds are studied for their ability to catch chemical stimuli and their cell renewal capacity. Vimentin RV202 is a protein employed as a marker for mesenchymal cells that can differentiate along different lineages and to self-renew, while Calretinin N-18 is employed as a marker of sensory cells, and ubiquitin is a protein crucial for guiding the fate of stem cells throughout development. In this study, a surface morphology investigation and an immunohistochemical analysis have been conducted. The results of the present study reveal, for the first time, the presence of Vimentin RV202 in a taste bud cell population of zebrafish. Some taste bud cells are just Vimentin RV202-immunoreactive, while in other cells Vimentin RV202 and Calretinin N-18 colocalize. Some taste buds are just reactive to Calretinin N-18. Vimentin RV202-immunoreactive cells have been observed in the connective layer and in the basal portion of the taste buds. The immunoreactivity of ubiquitin was restricted to sensory cells. Further studies are needed to elucidate the role of Vimentin RV202 in the maturation of taste bud cells, its potential involvement in the regeneration of these chemosensory organs, and its eventual synergic work with ubiquitin.

The gilthead seabream, one of the most important species in Mediterranean aquaculture, with an increasing status of exploitation in terms of production volume and aquafarming technologies, has become an important research topic over the years. The accumulation of knowledge from several studies conducted during recent decades on their functional and biological characteristics has significantly improved their aquacultural aspects, namely their reproductive success, survival, and growth. Despite the remarkable progress in the aquaculture industry, hatchery conditions are still far from ideal, resulting in frequent abnormalities at the beginning of intensive culture, entailing significant economic losses. Those deformities are induced during the embryonic and post-embryonic periods of life, and their development is still poorly understood. In the present review, we created a comprehensive synthesis that covers the various aspects of skeletal morphogenesis and anomalies in the gilthead seabream, highlighting the genetic, environmental, and nutritional factors contributing to bone deformities and emphasized the potential of the gilthead seabream as a model organism for understanding bone morphogenesis in both aquaculture and translational biological research. This review article addresses the existing lack in the literature regarding gilthead seabream bone deformities, as there are currently no comprehensive reviews on this subject.

Calcium-binding proteins (CaBPs) are members of a heterogeneous family of proteins able to buffer intracellular Ca2+ ion concentration. CaBPs are expressed in the central and peripheral nervous system, including a subpopulation of retinal neurons. Since neurons expressing different CaBPs show different susceptibility to degeneration, it could be hypothesized that they are not just markers of different neuronal subpopulations, but that they might be crucial in survival. CaBPs’ ability to buffer Ca2+ cytoplasmatic concentration makes them able to defend against a toxic increase in intracellular calcium that can lead to neurodegenerative processes, including those related to aging. An emergent model for aging studies is the annual killifish belonging to the Nothobranchius genus, thanks to its short lifespan. Members of this genus, such as Nothobranchius guentheri, show a retinal stratigraphy similar to that of other actinopterygian fishes and humans. However, according to our knowledge, CaBPs’ occurrence and distribution in the retina of N. guentheri have never been investigated before. Therefore, the present study aimed to localize Calretinin N-18, Parvalbumin, and S100 protein (S100p) in the N. guentheri retina with immunohistochemistry methods. The results of the present investigation demonstrate for the first time the occurrence of Calretinin N-18, Parvalbumin, and S100p in N. guentheri retina and, consequently, the potential key role of these CaBPs in the biology of the retinal cells. Hence, the suitability of N. guentheri as a model to study the changes in CaBPs’ expression patterns during neurodegenerative processes affecting the retina related both to disease and aging can be assumed.

Over the years, the gilthead seabream (Sparus aurata), a prominent species in Mediterranean aquaculture with an increasing production volume and aquafarming technologies, has become an important research focus. The accumulation of knowledge via several studies during the past decades on their functional and biological characteristics has significantly improved the aquacultural aspects, namely their reproductive success, survival, and growth. Despite the remarkable progress in the aquaculture industry, hatchery conditions are still far from ideal, resulting in frequent challenges at the beginning of intensive culture, entailing significant economic losses. Given its increasing importance and the persistent challenges faced in its aquacultural practices, a thorough review is essential to consolidate knowledge, and elucidate the intricate facets concerning its distribution, life cycle, growth dynamics, genetics, aquaculture methodologies, economic dimensions, and the challenges inherent to its cultivation.

The incidence rates of light-induced retinopathies have increased significantly in the last decades because of continuous exposure to light from different electronic devices. Recent studies showed that exposure to blue light had been related to the pathogenesis of light-induced retinopathies. However, the pathophysiological mechanisms underlying changes induced by light exposure are not fully known yet. In the present study, the effects of exposure to light at different wavelengths with emission peaks in the blue light range (400–500 nm) on the localization of Calretinin-N18 (CaR-N18) and Calbindin-D28K (CaB-D28K) in adult zebrafish retina are studied using double immunofluorescence with confocal laser microscopy. CaB-D28K and CaR-N18 are two homologous cytosolic calcium-binding proteins (CaBPs) implicated in essential process regulation in central and peripheral nervous systems. CaB-D28K and CaR-N18 distributions are investigated to elucidate their potential role in maintaining retinal homeostasis under distinct light conditions and darkness. The results showed that light influences CaB-D28K and CaR-N18 distribution in the retina of adult zebrafish, suggesting that these CaBPs could be involved in the pathophysiology of retinal damage induced by the short-wavelength visible light spectrum.

Background: Anorexia of aging, defined as a decrease in appetite and a preponderant loss of body weight occurring in late life, is one of the most common diseases affecting older people.The peptide hormone cholecystokinin (Cck) is known to play a key role in regulating food intake and satiety in higher vertebrates. In humans as well as in rats, an increased concentration of Cck was described as the basis of appetite loss in elderly. However, the role of increased plasma Cck concentrations in med-iating the age-related decrease in appetite remains to be established.Although in vitro studies are an excellent resource for investigating aging, the use of a model organism that shares and imitates the human physiological processes guarantees a better understanding of the in vivo mechanisms.African annual fishes from the genus Nothobranchius are emerging as a prominent model organism in biogerontology and developmental biology due to their short captive lifespan.Therefore, in the current study, we aimed to investigate the possibility of using the genus Nothobranchius to model the anorexia of aging and their potential contribution to better understanding the pathway by which Cck induce appetite loss in older people providing a comparative/evolutionary locali-zation of the current study model among the aging canonicals models, the morphology of its gastro-intestinal tract and its Cck expression pattern. Methods: The comparative/evolutionary investigation was conducted using the NCBI blastp (protein -pro-tein BLAST) and NCBI Tree Viewer. The macroscopic morphology, histological features, ultrastructural or-ganization of Nothobranchius rachovii gastrointestinal tract were investigated using stereomicroscope, Masson's trichrome and alcian blue-PAS staining, and transmission electron microscopy, respectively.The cck expression pattern was studied through immunofluorescence labeling, western blotting, and quantitative RT-PCR.Results: The intestine was folded into different segments divided into an anterior intestine made of a rostral intestinal bulb and an intestinal annex of lower diameter, mid and posterior intestine. The gradual tran-sition from the rostral intestinal bulb to the posterior intestine sections's epithelium is characterized by a gradual reduction in the striated muscular bundles, villi height, and goblet mucous cells count. The lining epithelium of the intestinal villi was characterized by a typical brush border enterocytes full of mi-tochondria. Moreover, Cck expression was detected in scattered intraepithelial cells concentrated in the anterior tract of the intestine.Conclusions: Our study introduces Nothobranchius rachovii as a model for anorexia of aging, giving the first bases on the gastrointestinal tract morphology and cck expression pattern. Future studies on young and elderly Notobranchius can divulge the contribution of cck in the mechanisms of anorexia associated with aging.& COPY; 2023 Elsevier GmbH. All rights reserved.

The brain-derived neurotrophic factor (BDNF) was discovered in the last century, and identified as a member of the neurotrophin family. BDNF shares approximately 50% of its amino acid with other neurotrophins such as NGF, NT-3 and NT-4/5, and its linear amino acid sequences in zebrafish (Danio rerio) and human are 91% identical. BDNF functions can be mediated by two categories of receptors: p75NTR and Trk. Intriguingly, BDNF receptors were highly conserved in the process of evolution, as were the other NTs’ receptors. In this review, we update current knowledge about the distribution and functions of the BDNF-TrkB system in the sensory organs of zebrafish. In fish, particularly in zebrafish, the distribution and functions of BDNF and TrkB in the brain have been widely studied. Both components of the system, associated or segregated, are also present outside the central nervous system, especially in sensory organs including the inner ear, lateral line system, retina, taste buds and olfactory epithelium.

The use of dental implants in oral rehabilitations has become increasingly common, thanks to the safety and predictability of these rehabilitations. Unfortunately, dental implants, being alloplastic devices, are not free from biomechanical complications, especially in the case in which the connections are complex and involve several components. The aim of the study is to highlight what could be surface alterations using different screwing torques, or by repeating the screwing process several times. In this study, 40 passant screws (Osstem®, South Korea Dental Implant Ebony Gold®) were examined under a Zeiss EVO LS 10 scanning electron microscope (SEM), operating with an accelerating voltage of 20 kV. Passant screws were subdivided into 4 groups: 30 Nmm tightening torque; maximum tightening torque; 2 times 30 Nmm tightening torque; no screwing, new ones (control group). There are no significant differences in the surfaces of the passant screws in SEM images, and the 100% of the passant screws is free of defects or fractures. Surely, further studies and investigations will certainly be needed to allow improvement of these devices.