•FPH are promising alternative emulsifiers to stabilize fish oil-in-water emulsions.•Sardine hydrolysates with low DH, 3% and 4%, led to more physically stable emulsions.•The previous emulsions were ...also more oxidatively stable.•Small-spotted catshark hydrolysates showed poor emulsifying properties.
The emulsifying and antioxidant properties of fish protein hydrolysates (FPH) for the physical and oxidative stabilization of 5% (by weight) fish oil-in-water emulsions were investigated. Muscle proteins from sardine (Sardina pilchardus) and small-spotted catshark (Scyliorhinus canicula) were hydrolyzed to degrees of hydrolysis (DH) of 3-4-5-6% with subtilisin. Sardine hydrolysates with low DH, 3% and 4%, presented the most effective peptides to physically stabilize emulsions with smaller droplet size. This implied more protein adsorbed at the interface to act as physical barrier against prooxidants. This fact might also be responsible for the higher oxidative stability of these emulsions, as shown by their lowest peroxide value and concentration of volatiles such as 1-penten-3-one and 1-penten-3-ol. Among the hydrolysates prepared from small-spotted catshark only the hydrolysate with DH 3% yielded a physically stable emulsion with low concentration of unsaturated aldehydes. These results show the potential of FPH as alternative protein emulsifiers for the production of oxidatively stable fish oil-in-water emulsions.
Abstract
In bony vertebrates, skeletal mineralization relies on the secretory calcium-binding phosphoproteins (Scpp) family whose members are acidic extracellular proteins posttranslationally ...regulated by the Fam20°C kinase. As scpp genes are absent from the elephant shark genome, they are currently thought to be specific to bony fishes (osteichthyans). Here, we report a scpp gene present in elasmobranchs (sharks and rays) that evolved from local tandem duplication of sparc-L 5′ exons and show that both genes experienced recent gene conversion in sharks. The elasmobranch scpp is remarkably similar to the osteichthyan scpp members as they share syntenic and gene structure features, code for a conserved signal peptide, tyrosine-rich and aspartate/glutamate-rich regions, and harbor putative Fam20°C phosphorylation sites. In addition, the catshark scpp is coexpressed with sparc-L and fam20°C in tooth and scale ameloblasts, similarly to some osteichthyan scpp genes. Despite these strong similarities, molecular clock and phylogenetic data demonstrate that the elasmobranch scpp gene originated independently from the osteichthyan scpp gene family. Our study reveals convergent events at the sparc-L locus in the two sister clades of jawed vertebrates, leading to parallel diversification of the skeletal biomineralization toolkit. The molecular evolution of sparc-L and its coexpression with fam20°C in catshark ameloblasts provides a unifying genetic basis that suggests that all convergent scpp duplicates inherited similar features from their sparc-L precursor. This conclusion supports a single origin for the hypermineralized outer odontode layer as produced by an ancestral developmental process performed by Sparc-L, implying the homology of the enamel and enameloid tissues in all vertebrates.
Display omitted
•Chondroitin sulfate was isolated from fish processing industry by-products.•CS Mw was determined by GPC and sulfation position by NMR and SAX-HPLC.•CS was isolated from Scyliorhinus ...canicula, Prionace glauca, and Raja clavata.•4S/6S ratio below 0.20 was observed for P. glauca and R. clavata.
Chondroitin sulfate (CS) was isolated from Scyliorhinus canicula (fin, head and skeleton), Prionace glauca (head), and Raja clavata (skeleton) by-products from fish processing industry using environmentally friendly processes. The molecular weight was determined by gel permeation chromatography and the sugar composition and sulfation position by NMR and SAX-HPLC after enzymatic digestion. The CSs showed a prevalent 6S GalNAc sulfation for the 3 species (4S/6S ratio lower than 1). A higher 6S sulfation was observed for P. glauca head and R. clavata skeleton (4S/6S ratio below 0.20) than for S. canicula (4S/6S ratio ca. 0.6). The existence of CS samples with such low 4S/6S ratio has only been observed before in a rare species of shark (Mitsukutina owatoni, globin shark). The good extraction yields achieved make S. canicula, P. glauca and R. clavata fish industry by-products a useful source of 6-sulfated chondroitin sulfate.
This study was carried out in the Marine Sciences Laboratory of Agriculture Faculty at Tishreen University, in collaboration with the Higher Commission for Scientific Research, on the Small Spotted ...Catshark Scyliorhinus canicula (Linnaeus, 1758) in the Syrian marine water (Eastern Levant of Mediterranean sea); From Rass Albassit northward ( 35° 55 N), to the Lebanese borders southward (°34 50´ N). During the period January 2012 to September 2013. 417 specimens (231 females, 186males) were collected at depths 50-250 m, from sandy or sandy-muddy bottoms by different fishing gears; mainly hook sub bottom. S. canicula suffers an overfishing into the Syrian marine water. The highest fishing quantity was during spring and summer. The total length of specimens ranged from 225 to 515 mm TL, and weighed from 22 - 380 g. Smallest specimens matured of males and females were 355, 350 mm, respectively. The total length ranged from 355 -500 mm TL for adult males, and 350 -515 mm TL for adult females. S. canicula is an oviparous species. The largest yolky oocytes diameter was 12 mm, and weighed 1.3 g. The ripe oocytes is covered and ovulated as an egg capsule. The length of egg capsules ranged from 42 -50 mm, their width from 16-18 mm, and their mass reached to 4.8 g.
Sharks play a key role in the functioning of marine ecosystems and maintenance of trophic web balance, including life cycles of parasites co-occurring in their habitats. We investigated the structure ...of parasite communities of three sympatric shark species (Etmopterus spinax, Galeus melastomus, and Scyliorhinus canicula) and explored both the influence of host features in shaping the communities and their role as biological indicators of environment stability in the Gulf of Naples (central Mediterranean Sea), a geographical area characterized by strong anthropic pressure. Parasites found were all trophic transmitted helminths with a complex life cycle, except Lernaeopoda galei, that is a ecto-parasite copepod. Communities were all similarly impoverished with 4-5 component species and low values of species richness and diversity. Higher abundance of cestode larvae of the genus Grillotia was found in G. melastomus, although their dominance in all host species suggests that the three sharks have a similar role as intermediate/paratenic hosts in local food webs. Similarly, high abundance of Grillotia larvae could also suggest the occurrence of high abundance of largest top predators in the area. Host morphological (fork length in S. canicula and G. melastomus and body condition index in G. melastomus) and physiological (sex and gonadosomatic and hepatosomatic indices in S. canicula) variables were differently correlated to parasite community structures depending by host species. Potential reasons for the present impoverished parasite communities are discussed.
Summary
1. Determining how animals move within their environment is a fundamental knowledge that contributes to effective management and conservation. Continuous ‘round‐the‐clock’ animal movement ...data are frequently gathered using biotelemetry technology, providing discrete data packages on the presence–absence of animals at known locations through time. Current analyses of such data do not generally account for the interconnectivity of locations as animals move between them and consequently do not integrate graphically or statistically a temporal component to spatial changes.
2. Here, we describe the novel application of network analyses to electronic tag data whereby nodes represent locations and edges the movements of individuals. We demonstrate some of the descriptive and quantitative approaches for determining how an animal’s movement interconnects home range habitats. Telemetry data from arrays of recorders provide movement data of individual animals, and as examples of the method proposed, we examine the movements of two distinct shark species, the small‐spotted catshark (Scyliorhinus canicula) and the Caribbean reef shark (Carcharhinus perezi). In doing so, we consider both local and global network properties from an animal movement perspective and simulate the effects of node disruption as a proxy for habitat disturbance.
3. Comparative visual representations of two catshark movement networks suggest, for example, potential differences in space use. Multiple regression quadratic assignment procedure shows that habitat is a significant predictor of movement behaviour.
4. Null modelling of C. perezi movement data, corrected for the spatial restriction of static nodes, demonstrated a significant, non‐random distribution of directed movements among sites. Additionally, the connectivity of this animal’s movement network is significantly reduced through targeted disruption of a site of high centrality but not through disruption of a randomly selected site.
5. Network theory is a well‐established theoretical framework and its integration into the fast developing field of animal movement and telemetry might improve significantly how we interpret animal space use from electronically recorded data. This technique has potentially wide application in animal behaviour but may also inform the management of habitat harbouring threatened or endangered species via the simulation, modelling and intuitive visualisation of animal movement interactions.
Video
•A simulated heatwave altered hematological parameters in temperate catsharks.•It increased leukocyte and thrombocyte counts, along with ventilation rates.•Erythrocyte counts and size ratio decreased ...in response to this treatment.
As Earth’s temperature continues to rise, sudden warming events, designated as marine heatwaves (MHWs), are becoming more frequent and longer. This phenomenon is already shown to significantly impact marine ecosystems and respective fauna. While experimental acclimation to higher temperatures is known to affect predatory behavior, metabolism and overall fitness of sharks, the effects of short-term exposure to high temperatures on sharks’ physiology has yet to be investigated in a MHW context. Thus, the aim of our work was to study the impact of a category II MHW (Δ3 °C, 15 days) on: i) hematological parameters (total erythrocytes, leukocytes, thrombocytes, erythrocyte nuclear abnormalities (ENAs) counts, and nucleus to cytoplasmic ratio), ii) heart and spleen to body ratios, and iii) ventilation rates of juvenile catsharks (Scyliorhinus canicula). We found that MHW exposure led to significant changes in normal blood cell counts, by lowering erythrocyte counts and nucleus to cytoplasm ratio, and increasing leukocyte and thrombocyte counts. Moreover, ventilation rates increased consistently over the course of the MHW. However, there were no changes regarding the presence of ENA, as well as spleen and heart to body ratios. Our findings indicate limited capabilities for coping with sudden warming events, suggesting potential disruption in shark physiological homeostasis as the frequency, duration and intensity of MHWs are expected to be strengthened.
Plastics are widely diffused in the oceans and their ingestion by marine organisms is raising concern for potentially adverse effects. The risk of harmful interactions with marine plastic pollution ...depends on the biology of the species as well as the distribution and abundance of the different plastic types.
The aim of this study was to assess the occurrence of plastic ingestion by the small-spotted catshark (Scyliorhinus canicula), one of the most abundant elasmobranchs in the Mediterranean Sea. The expression levels of genes indicative of total immune system function were analyzed to gather preliminary data for further investigation of any potential correlations between plastic presence and immune activation.
One hundred catsharks were collected during the Spring 2018 in two geographic locations in the southern region of the central Mediterranean Sea: 1) near Mazara del Vallo, SW Sicily and 2) near Lampedusa island, Italy's southernmost. Standard measurements were recorded for each specimen and its organs and sex was determined. The gastrointestinal tract (GIT) was preserved for plastic detection and identification. Where present, plastics (macro- and micro-) were characterized in terms of size, shape and polymer typology through microscopy and μ-Raman spectroscopy. Spleen from a subset of thirty samples was preserved for RNA extraction, then used to quantify by real time PCR the transcripts of T cell receptor beta (TCRB), T cell receptor delta (TCRD) and IgM genes.
The results indicated that ingestion of plastic is widespread, with microplastics (MP, from 1 μm to <1 mm) abundantly present in nearly all samples and macroplasticplastic (MaP, > 1 cm) in approximately 18% of the specimens collected. A significant increase in the expression of TCRB, TCRD and IgM was observed in the spleen of MaP + specimens from Mazara del Vallo waters, in parallel with 67% increase in liver weight.
While the presence of MP alone is not enough to induce a strong activation of the immunity, some type of plastics falling into the MaP category may be more toxic than others and crucial in the activation of the immune response.
The results of this study represent a first evidence that plastic pollution represents an emerging threat to S. canicula, the Mediterranean food web and human consumers.
•We describe microplastics and macroplastics in small spotted sharks, Scyliorhinus canicula.•We used samples from two geographic locations in the southern region of the central Mediterranean Sea.•We characterized the plastics in the shark’s gastrointestinal tract (GIT) using microscopy and μ-Raman spectroscopy.•We analyzed morphometric data in correlation of geographical location and plastic load.•We measured the expression of immune-related genes for potential correlation to location and plastic detection.
Cancer therapy is currently a major challenge within the research community, especially in reducing the side effects of treatments and to develop new specific strategies against cancers that still ...have a poor prognosis. In this context, alternative strategies using biotechnologies, such as marine peptides, have been developed based on their promise of effectivity associated with a low toxicity for healthy cells. The purpose of the present paper is to investigate the active mechanism of two peptides that were isolated from the epigonal tissue of the lesser spotted dogfish
L., identified NFDTDEQALEDVFSKYG (K092A) and EAPPEAAEEDEW (K092B) on the in vitro growth inhibition of ZR-75-1 mammary carcinoma cells and MDA-Pca-2b prostate cancer cells. The effects of the peptides on cell proliferation and cell death mechanisms were studied by the flow cytometry and immunofluorescence microscopy approaches. The results have shown the onset of both K092A- and K092B-induced early cytoskeleton changes, and then cell cycle perturbations followed by non-apoptotic cell death. Moreover, impedance perturbation and plasma membrane perforation in ZR-75-1 K092A-treated cell cultures and autophagy inhibition in MDA-Pca-2b K092B-treated cells have been observed. In conclusion, these two bioactive peptides from dogfish exhibit antineoplastic activity on the human prostate and breast cancer cells in vitro.
The study aims to identify antibacterial properties in unfertilized eggs of Scyliorhinus canicula and Scyliorhinus stellaris. Despite challenging marine conditions, these eggs retain their integrity ...for extended periods and remain unaffected by pathogens. The antibacterial activity was measured using minimum inhibitory and minimum bactericidal concentration analysis. The eggs of S. stellaris exhibited a slight inhibitory effect against Staphylococcus aureus and Listeria monocytogenes, whereas both species' eggs showed no activity against gram‐negative microorganisms.
PDF
