Epidermal Mucus Research Articles

De novo assembly of the sea trout (Salmo trutta m. trutta) skin transcriptome to identify putative genes involved in the immune response and epidermal mucus secretion.

In fish, the skin is a multifunctional organ and the first barrier against pathogens. Salmonids differ in their susceptibility to microorganisms due to varied skin morphology and gene expression patterns. The brown trout is a salmonid species with important commercial and ecological value in Europe. However, there is a lack of knowledge regarding the genes involved in the immune response and mucus secretion in the skin of this fish. Thus, we characterized the skin transcriptome of anadromous brown trout using next-generation sequencing (NGS). A total of 1,348,306 filtered reads were obtained and assembled into 75,970 contigs. Of these contigs 48.57% were identified using BLAST tool searches against four public databases. KEGG pathway and Gene Ontology analyses revealed that 13.40% and 34.57% of the annotated transcripts, respectively, represent a variety of biological processes and functions. Among the identified KEGG Orthology categories, the best represented were signal transduction (23.28%) and immune system (8.82%), with a variety of genes involved in immune pathways, implying the differentiation of immune responses in the trout skin. We also identified and transcriptionally characterized 8 types of mucin proteins–the main structural components of the mucosal layer. Moreover, 140 genes involved in mucin synthesis were identified, and 1,119 potential simple sequence repeats (SSRs) were detected in 3,134 transcripts.

Chemical Composition and Antioxidant Activities of Catfish Epidermal Mucus

The antioxidant activity of Clarias gariepinus and Clarias sp.1 epidermal mucus were determined. Aqueous extracts of C.sp1 contained relatively higher levels of protein concentration [602.04mg g-1 fresh weight] than other extracts while the organic extracts (aqueous phase) of C.sp1 gave higher levels of protein concentration (43.50mg g-1 fresh weight) than dichloromethane phase for both species. The chemical composition analysis revealed the values of moisture, ash, crude protein, fat and carbohydrate contents present in both species. The DPPH scavenging effect of all extracts and standards on the DPPH radical decreased in order of: ascorbic acid > BHT > dichoromethane phase extract of C. gariepinus > aqueous phase of C. gariepinus > acidic extract of C.sp1 > acidic extract of C. gariepinus > dichloromethane phase extract of C.sp1 > aqueous phase extract of C.sp1 > aqueous extract of C. gariepinus > aqueous extract of C.sp1 at the concentration of 100ug/ml, respectively. Reducing power activities in all extracts increased with increasing concentration except for acidic extract of C. gariepinus which decreased at concentration of 100ug/ml. The Ferric Reducing Antioxidant Power (FRAP) also increased as the concentration increased for all extracts. However, all extracts showed lower scavenging activity, reducing power and FRAP activities than BHT and ascorbic acid at the same concentrations. This preliminary information suggest that mucus from these fish species may be a source of novel antioxidant agents for fish and human health related applicants.

A comparison of changes in stable isotope ratios in the epidermal mucus and muscle tissue of slow‐growing adult catfish

AbstractAlthough stable isotope analysis is a powerful tool for determining diet, migration patterns and the structure of food webs in aquatic systems, the slow response of isotopic ratios in the widely used muscle tissue often hampers this approach, particularly in slow‐growing or adult fishes. We conducted a diet‐switch experiment to compare the changes in the stable carbon isotope ratio (δ13C values) in the epidermal mucus and muscle tissue of five‐year‐old catfish (Silurus asotus). The isotope ratios in noninvasively sampled mucus changed more rapidly than those in the muscle tissue. As isotopic change in mucus was relatively rapid, this technique can be used over a finer timescale than traditional isotopic analyses using the muscle tissue. The isotopic change half‐life in our experimental condition was 200 days, which would not be short enough for some research purposes. Examining mucus along with the muscle would enable food habits of slow‐growing fishes to be determined over different timescales. However, the rate of isotopic change in the mucus was negatively affected by the size of fish and was slower than the previously reported rates in juvenile steelhead. These findings suggest that mucus turnover rates need to be determined prior to the field data interpretation.

Effects of Fish-Derived Biological Preservatives on Cold Storage of Grass Carp (Ctenopharyngodon idellus) Fillets

Two kinds of fish-derived natural antimicrobial substances, protamine and catfish ( Clarias fuscus ) epidermal mucus extract (CEME), were evaluated for their effect on the quality of grass carp fillets. Fillets were atmosphere packaged in cast polypropylene bags and were stored at 4°C in a low-temperature incubator without light. Solutions (0.5%, wt/vol) of CEME and protamine were used for dip pretreatment, respectively. Bacteriological (aerobic plate count, Shewanella putrefaciens , Pseudomonas fluorescens ) and physicochemical (pH, total volatile basic nitrogen, K value, surface color, texture profiles, water distribution) parameters and volatile odor compounds were measured on days 0, 3, 6, 9, 12, and 15. The results indicated that CEME and protamine could improve all bacteriological and physicochemical indexes, except water distribution within muscle. In comparison, CEME had a more inhibitory effect, as determined by the aerobic plate count, and was more effective in inhibiting the growth of P. fluorescens ; however, protamine was more effective in preventing the production of sulfur-organic (H2S) group substances. Protamine was more effective in inhibiting the growth of S. putrefaciens . This research suggests that protamine and CEME have the potential to improve the quality and extend the shelf life of grass carp fillets.

Bioactive potency of epidermal mucus extracts from greasy grouper, Epinephelus tauvina (Forsskal, 1775)

Objective: To study the bio-potency of epidermal mucus from Epinephelus tauvina. Methods: Mucus was extracted with acidic, organic and aqueous solvents. Protein, carbohydrate, lipid, amino acid and fatty acid content of mucus extracts were quantified by UV-spectrophotometer, high performance liquid chromatography and gas chromatography- mass spectrometer, respectively. Antimicrobial activity was tested against five human and fish pathogens by using agar well diffusion method. The molecular weight of peptides was determined using sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The haemolytic activity of extracts was tested against chick, goat, cow and human red blood cell. Results: Protein contributed with maximum of 26.25% in crude mucus. Arginine was recorded maximum of (133.9 nmol/mL) in crude mucus. 2,4,6-Decatrienoic acid and bis (a-chloroethyl) sulfone were confirmed in organic extract. The antimicrobial activity of acidic extract was significant. Among the human pathogens, maximum zone of inhibition ((26.0 ± 0.3) mm) was observed against Proteus mirabilis. Whereas, among fish pathogens maximum zone of inhibition ((25.0 ± 0.1) mm) was observed against Vibrio parahemolyticus. The activity of other two extracts was not remarkable. The molecular weight of peptides ranged from 115.5- 37.1 kDa in acidic extract was determined. Chicken and goat blood were found to be highly vulnerable to the lysis. Conclusions: The whole mucus could be a promising source with numerous bioactive- potency. Consequently, this preliminary information suggested that mucus is a source of novel antimicrobial agents for fish and human health related applications.

Angiotensins processing activities in the venom and epidermic mucus of Scorpaena plumieri

The venom of marine animals is a rich source of compounds with remarkable selectivity and functional diversity. Scorpaena plumieri is the most venomous fish in the Brazilian fauna and is responsible for relatively frequent accidents involving anglers and bathers. In humans, its venom causes edema, erythema, ecchymoses, anxiety, nausea, vomiting, and syncope. The venom is chemically characterized by Sp-CTx, a enzyme able to generate an initial endothelium-dependent relaxation response, followed by a contraction response. This study sought to investigate the proteolytic activities regarding vasopeptides angiotensin I and II. Both the venom and the epidermal mucus presented angiotensin conversion activity for angiotensin I, as well as a capacity to form Ang 1–7 directly via Ang I and II. Captopril (10 μM) and EDTA (1 mM) were able to abolish the converting activity of the venom and the epidermal mucus, representing the first description of a converting activity in S. plumieri venom and epidermal mucus.

Mucus cells in koi (Cyprinus carpio) scale epidermis

Morphological and dynamic characteristics of epidermal mucus cells were examined in intact scales of Cyprinus carpio. Mucus cells were identified by alcian blue staining and live mucus cells characterized with differential interference contrast microscopy. Mucus cell pores were shown to be narrow slits or triangular-shaped openings which are invariably situated at cell-cell junctions. Small granules were often located at or just below the openings with larger granules positioned deeper into the cell. The large granules were observed to undergo a bubbling-like activity, where a granule suddenly appears, enlarges and then abruptly disappears. Situated below the large granules is a dense matrix of quiescent small, tightly packed mucin granules. The findings suggest that mature epidermal mucus cells are structurally ordered with respect to secretory activity, where small numbers of initially basally located, densely packed granules rapidly expand in a location proximal to the pore and presumably prior to mucus release through the pore.

Epithelial Cell-Derived a Disintegrin and Metalloproteinase-17 Confers Resistance to Colonic Inflammation Through EGFR Activation

Epithelial regeneration is a key process for the recovery from ulcerative colitis (UC). Here we demonstrate that a disintegrin and metalloproteinase-17 (ADAM17), a main sheddase for tumor necrosis factor (TNF)-α, is essential for defensive epithelial properties against UC by promoting epithelial cell growth and goblet cell differentiation in mouse and human. Mice with systemic deletion of Adam17 developed severe dextran sulfate sodium-induced colitis when compared to mice with myeloid cell Adam17 deletion or control littermates. ADAM17 was predominantly expressed by regenerating epithelia in control mice, and its loss or inhibition attenuated epidermal growth factor receptor (EGFR) activation, epithelial proliferation, mucus production and barrier functions. Conversely, ectopic EGFR stimulation promoted epithelial regeneration thereby partially rescuing the severe colitis caused by ADAM17 deficiency. In UC patients, epithelial ADAM17 expression positively correlated with both cell proliferation and goblet cell number. These findings suggest that maintaining ADAM17–EGFR epithelial signaling is necessary for the recovery from UC and would be beneficial to therapeutic strategies targeting ADAM17-mediated TNF-α shedding.

Short report on the ectoparasitic fauna from a wild Epinephelus marginatus and osmotic shock efficiency on their removal

Short report on the ectoparasitic fauna from a wild Epinephelus marginatus and osmotic shock efficiency on their removal

Earthworm epidermal mucus: Rheological behavior reveals drag-reducing characteristics in soil

Soil adhesion occurs on the surfaces of soil-tillage implements during use. This phenomenon increases energy consumption and decreases tillage quality. Nevertheless, earthworms can comfortably move in moist or adhesive soil, although with soil particles seldom sticking to bodies. The influence of earthworm movement on epidermal mucus provides perspective for the interpretation of the results on drag-reducing characteristics. The amino acid composition and rheological behavior of epidermal mucus samples from three earthworm ecological species were studied in the laboratory. These earthworm species were represented by Eisenia fetida, Aporrectodea trapezoides, and Amynthas pingi, which were collected from the Typic Hapludolls with loam textures. An electro-stimulation device was developed to extract and collect approximately 5g of mucus (field weight) from several individuals of 30g in total of each earthworm species. Mucus samples from the three earthworm species were found to contain 16 amino acids. Aspartic acid, glutamic acid, and valine were present in relatively high concentrations in all the samples. The rheological behavior of earthworm epidermal mucus was investigated via continuous shear, thixotropy, and oscillation tests. The apparent viscosity initially increased and then decreased with the increase in mucus shear rate. The thixotropic behavior was demonstrated as the apparent viscosity of epidermal mucus recovered gradually with the decrease in shear rate. Oscillatory tests showed that the viscoelastic behavior of epidermal mucus can be altered with changes in oscillation frequency. A five-layer interface contact model revealed that the apparent viscosity of mucus changes with earthworm movement, thereby reducing the soil adhesion and friction resistance toward the earthworm body surface. Overall, this study revealed the drag-reducing characteristics of earthworm epidermal mucus and inspired the development of some potential bionic applications with lubricating functions for soil-tillage implements.

The effects of garlic-supplemented diets on skin mucosal immune responses, stress resistance and growth performance of the Caspian roach (Rutilus rutilus) fry.

This study was conducted to evaluate the effects of garlic supplementation on some skin mucus immune parameters, mucus antimicrobial activity and growth performance of the Caspian roach (Rutilus rutilus caspicus) fry. Fish (1±0.07g) were divided into four groups fed diets containing 0 (control), 5, 10 and 15gkg(-1) garlic for 8 weeks. The results showed that there was a significant increase in weight gain and specific growth rate in those fish fed garlic diets compared with the control (P<0.05). Condition factor was not significantly affected by garlic dosage. At the end of trial, the epidermal mucus protein level, alkaline phosphatase and antimicrobial activity against 2g-negative bacteria (Escherichia coli and Serratia marcescens) and gram-positive bacteria (Streptococcus faecium and Micrococcus luteus) were measured. Skin mucus alkaline phosphatase, protein levels and antimicrobial activity were increased following garlic administration, and the bacterial growth inhibition zones were significantly elevated in garlic-fed fish (P<0.05). In salinity stress experiment, no differences were observed for survival rate among the experimental diets. No mortality was recorded during the feeding trial. These results indicated that dietary garlic beneficially affects the skin mucus immune parameters and growth performance of the Caspian roach fry.

Design and membrane-disruption mechanism of charge-enriched AMPs exhibiting cell selectivity, high-salt resistance, and anti-biofilm properties.

Cationic antimicrobial peptides (AMPs) are essential components of the innate immune system, offering protection against invading pathogenic bacteria. In nature, AMPs serve as antibiotics with broad-spectrum antimicrobial and anti-biofilm properties. However, low effective stability in high-salt environments and physiological instability in biological membranes limit the applicability of naturally occurring AMPs as novel therapeutics. We therefore designed short synthetic cationic peptides by substituting key residues in myxinidin, an AMP derived from the epidermal mucus of hagfish, with lysine (Lys, K), arginine (Arg, R), and tryptophan (Trp, W). The resultant myxinidin analogs exhibited strong antimicrobial activity against both Gram-positive and Gram-negative bacteria, including multidrug-resistant strains, even under high-salt conditions. Moreover, these peptides showed high binding affinity for both lipopolysaccharides and lipoteichoic acids and inhibited biofilm formation by most bacteria, but did not cause significant lysis of human red blood cells and were not cytotoxic to normal human keratinocytes. Circular dichroism analysis revealed that myxinidin and its analogs assumed α-helical or β-sheet structures within artificial liposomes and bacterial membranes. In addition, bacterial killing and membrane permeation experiments demonstrated that the myxinidin analogs permeated through bacterial membranes, leading to cytoplasmic disruption and cell death. Taken together, these findings suggest myxinidin analogs may be promising candidate antibiotic agents for therapeutic application against antibiotic-resistant bacteria.

Elucidation of innate immune components in the epidermal mucus of different freshwater fish species

Elucidation of innate immune components in the epidermal mucus of different freshwater fish species

Skin mucus proteome of gilthead sea bream: A non-invasive method to screen for welfare indicators.

In teleosts, the skin mucus is the first physical barrier against physical and chemical attacks. It contains components related to metabolism, environmental influences and nutritional status. Here, we study mucus and composition based on a proteome map of soluble epidermal mucus proteins obtained by 2D-electrophoresis in gilthead sea bream, Sparus aurata. Over 1300 spots were recorded and the 100 most abundant were further analysed by LC-MS/MS and identified by database retrieval; we also established the related specific biological processes by Gene Ontology enrichment. Sixty-two different proteins were identified and classified in 12 GO-groups and into three main functions: structural, metabolic and protection-related. Several of the proteins can be used as targets to determine fish physiological status: actins and keratins, and especially their catabolic products, in the structural functional group; glycolytic enzymes and ubiquitin/proteasome-related proteins in the metabolic functional group; and heat shock proteins, transferrin and hemopexins, in the protection-related group. This study analyses fish mucus, a potential non-invasive tool for characterising fish status, beyond defence capacities, and we postulate some putative candidates for future studies along similar lines.

Fish mucus versus parasitic gnathiid isopods as sources of energy and sunscreens for a cleaner fish

The cleaning behaviour of the bluestreak cleaner wrasse Labroides dimidiatus is extensively used as a model system for understanding cooperation. It feeds mainly on blood-sucking gnathiid isopods and also on the epidermal mucus of client fish; the nutritional quality of these foods, however, is unknown. The epidermal mucus of reef fish contains ultraviolet (UV)-absorbing compounds (mycosporine-like amino acids, MAAs), which are only obtained via the diet; nevertheless, while La. dimidiatus has high amounts of MAAs in its mucus, their source is unknown. Therefore, the energetic value (calories and protein estimated using carbon and nitrogen) and MAA level in gnathiids and mucus from several clients [parrotfishes, wrasses (Labridae), and a snapper (Lutjanidae)] were determined. The energetic value of mucus and gnathiids varied among fishes. Overall, carbon, nitrogen, calories, and protein per dry weight were higher in the mucus of most client species compared to gnathiids. Thus, depending on the client species, mucus may be energetically more advantageous for cleaner wrasse to feed on than gnathiids. UV absorbance, a confirmed proxy for MAA levels, indicated high MAA levels in mucus, whereas gnathiids had no detectable MAAs. This suggests that La. dimidiatus obtain MAAs from mucus but not from gnathiids. Hence, in addition to energy, the mucus of some clients also provides La. dimidiatus with the added bonus of UV-absorbing compounds. This may explain why cleaner fish prefer to feed on mucus over gnathiid isopods. The likely costs and benefits to clients of the removal of UV protecting mucus and parasitic gnathiids, respectively, and the variation in benefits gained by cleaner fish from feeding on these foods may explain some variation in cooperation levels in cleaning interactions.

Identification of the Atlantic cod l-amino acid oxidase and its alterations following bacterial exposure

Antibacterial factors that are present in epidermal mucus of fish have a potential role in the first line of host defence to bacterial pathogens. This study reports the identification of l-amino acid oxidase (LAO) in Atlantic cod (GmLao) and the changes in the molecule following bacterial exposure. The gmlao transcripts and LAO activity were present on both the body surface and in the internal organs of the fish. Relative mRNA level of gmlao increased significantly in the gills, the spleen and the head kidney (up to 8-fold) of fish that were challenged with the pathogen Vibrio anguillarum. The gmlao expression in skin was 4-fold higher in challenged fish. Our data indicate that LAO may be an important effector of antibacterial defence in Atlantic cod.

In Vitro Effects of Mucus from the Mantle of Compatible (Lymnaea elodes) and Incompatible (Helisoma trivolvis) Snail Hosts on Fascioloides magna Miracidia.

The epidermal mucus covering the surface of a snail represents an important barrier to trematode larvae attempting to penetrate the snail and may play a role in mediating snail-trematode compatibility. In this study, Facioloides magna miracidia were exposed to mucus harvested from a compatible snail host, Lymnaea elodes (palustris), and from an incompatible snail, Helisoma trivolvis . In vitro treatment of freshly hatched miracidia with snail-derived mucus exerted dramatically different effects on larvae depending on snail species. At the lowest dilution of mucus tested (1:3) mean damage rates (tegumental damage and/or larval lysis and death) were as high as 100% for miracidia exposed to H. trivolvis mucus, while none of F. magna miracidia were damaged in L. elodes mucus. A dilution series for each snail species, and treatments with heat and proteinase K were performed to characterize the component(s) of mucus inducing the observed morphological changes. The damaging effects of H. trivolvis mucus were concentration dependent and completely abrogated by heat (65 C, 30 min) and proteinase treatment, strongly implicating a heat-labile protein(s) in mucus as the active cytotoxic agent(s). In contrast to our prediction that miracidial contact with mucus of compatible L. elodes would trigger larval transformation, mucus from either snail species tested exhibited little to no activity. Overall these data demonstrate the presence of a potent cytotoxic protein-like factor in the mucus of F. magna -incompatible H. trivolvis , and its absence in the mucus of the compatible snail, L. elodes . This finding supports the notion that the epidermal mucus layer may be serving as an important determinant of larval trematode-snail compatibility.

Proximate analysis of different groups of irradiated alginic acid

Background: Seaweeds contain significant quan��es of lipids, protein, vitamins and minerals. Aquavac Ergosan contains 1% alginic acid extracted from two brown seaweeds, Laminaria digitata and Ascophyllum nodosum. Both in vivo and in-vitro researches have mainly been focused on the effect of Ergosan on fish growth, survival rate, reproducve performance and innate immunity in blood and epidermal mucus. Despite numerous studies on the ef fects of Ergosan on immune system of aquac animals and evaluaon of seaweeds in proximate analysis, there is no data available on proximate analysis of irradiated Ergosan extract (alginic acid). Therefore, the aim of this study was to assess the effect of on different groups of irradiated alginic acid (10, 20, 30, 40 and 50 KGy) for analyzing proximate composion. Materials and Methods: Alginic acid was prepared from the sonicated Ergosan extract. The Alginic acid extracted from Ergosan was irradiated with a gamma cell. The protein and lipid content and Moisture and ash were recorded. Results: Stascal analysis showed no signif icant dif ferences among all of groups in terms of protein, lipid, ash and moisture. Conclusion: Radiaon processing is a very convenient tool for imparng desirable effects in polymeric materials. The polysaccharide degradaon by gamma or ultraviolet irradiaon is free of iniators. High energy radiaon technique can be effecvely used to decrease the molecular weight of different polysaccharides such as alginate and Chitosan. Based on the results of this study, gamma irradiaon of alginic acid as natural polysaccharide had no effect on crude protein, crude lipid, moisture and ash.

Reducing sea lice (Lepeophtheirus salmonis ) infestation of farmed Atlantic salmon (Salmo salar L.) through functional feeds

Health diets for Atlantic salmon have become an important component of the integrated pest management strategies targeting sea lice. A challenge trial was performed to examine the effect of supplementing salmon diets with either immunostimulants or essential oils. One control and four experimental diets containing immunostimulants or natural identical extracts were fed to Atlantic salmon in triplicate tanks for 4 weeks before challenging the fish with the sea lice copepodids. Prevalence of infection was 100%, and the mean abundance of infection was 21.2. The lowest mean lice count of 17 per fish (P < 0.05) was found in the group fed a mix of natural identical plant extracts (PX I). This represents a 20% reduction in infection, showing the potential for health diets to be employed as a tool to help control sea lice. To gain an understanding of the mechanisms of action underlying this protection, fish fed the control diet and fish fed the PX I diet were compared using quantitative histology of the epidermis and proteomic analysis of epidermal mucus. No significant differences were seen in the thickness of the epidermis or mucous cell percentage area, but differences in expression were seen for a number of proteins, including heat shock proteins, in epidermal mucus.

Acclimation behaviour and bio-chemical changes during anemonefish (Amphiprion sebae) and sea anemone (Stichodactyla haddoni) symbiosis

Anemonefishes are known to exhibit an obligate symbiotic relationship with a limited number of sea anemone species. This has raised queries about the adaptive mechanisms of these fishes involved. The present study was carried out to understand the role of visual and chemical cues used for host recognition and the bio-chemical changes that occur during acclimation by the fishes. The experiments used the fishes Amphiprion sebae (a common anemone associate), Terapon jarbua (a control fish that does not associate with sea anemone) and Stichodactyla haddoni (an anemone commonly hosting anemonefishes). The results suggested that fish settlers use visual, tactile and chemical cues to select and distinguish their hosts. Furthermore, the acclimation times of A. sebae with the anemone host decreased exponentially during repeated trials. This fish apparently secreted a protective mucus. The epidermal mucus of A. sebae possessed unique glyco-proteins compared with T. jarbua. Chemical analyses showed that A. sebae and S. haddoni produced similar chemical substances, but T. jarbua produced a different kind of glycoprotein. This study helps to explain how anemonefishes are able to live with their host anemone, whereas other fishes are not.