Exploring sample cross-contamination in fish epidermal mucus

Cross-contamination of epidermal mucus was assessed at three sampling locations on the bodies of Pacific halibut Hippoglossus stenolepis by inducing contact between fish coated with labelled synthetic mucus and non-treated fish. Results indicate a positive relationship between sampling site exposure and sample contamination and that mucous sample cross-contamination can be mitigated by sampling in a location protected from external contact.     

A comparative study of superoxide dismutase in various animal species

1. Superoxide dismutase activity has been determined in liver homogenates of five species. There were no significant differences in the activities of the enzyme in the rat, rainbow lizard, wall gecko and chicken. The activity was significantly lower in the fish. 2. The order of activity of the enzyme in the organs/tissues of the rat was liver greater than kidney greater than heart greater than skeletal muscle greater than brain greater than lung greater than spleen greater than spinal cord greater than retina greater than pancrease greater than lens greater than small intestine. 3. Inhibition studies with cyanide showed that the enzyme in the liver of the various animal species was inhibited by cyanide. 4. The developmental pattern for the enzyme showed no significant changes in the liver of the rat from birth and up to 7 weeks after. However, the activity increased at about 8 weeks and remained constant to adult life.     

Comparison of antimicrobial activity in the epidermal mucus extracts of fish

The mucus layer on the surface of fish consists of several antimicrobial agents that provide a first line of defense against invading pathogens. To date, little is known about the antimicrobial properties of the mucus of Arctic char (Salvelinus alpinus), brook trout (S. fontinalis), koi carp (Cyprinus carpio sub sp. koi), striped bass (Morone saxatilis), haddock (Melanogrammus aeglefinus) and hagfish (Myxine glutinosa). The epidermal mucus samples from these fish were extracted with acidic, organic and aqueous solvents to identify potential antimicrobial agents including basic peptides, secondary metabolites, aqueous and acid soluble compounds. Initial screening of the mucus extracts against a susceptible strain of Salmonella enterica C610, showed a significant variation in antimicrobial activity among the fish species examined. The acidic mucus extracts of brook trout, haddock and hagfish exhibited bactericidal activity. The organic mucus extracts of brook trout, striped bass and koi carp showed bacteriostatic activity. There was no detectable activity in the aqueous mucus extracts. Further investigations of the activity of the acidic mucus extracts of brook trout, haddock and hagfish showed that these fish species had specific activity for fish and human pathogens, demonstrating the role of fish mucus in antimicrobial protection. In comparison to brook trout and haddock, the minimum bactericidal concentrations of hagfish acidic mucus extracts were found to be approximately 1.5 to 3.0 times lower against fish pathogens and approximately 1.6 to 6.6 folds lower for human pathogens. This preliminary information suggests that the mucus from these fish species may be a source of novel antimicrobial agents for fish and human health related applications.     

A comparative study of submicroscopic structures of protoplasts of various yeast species

A submicroscopic structure was studied of protoplasts of five different yeast species multiplying by budding, formation of cross septum and by a division typical for apiculate yeasts. The protoplasts retain their species specificity. Most considerable changes typical for the conversion of a cell to protoplast are found in membrane cell systems. The reduction of membranes of the endoplasmic reticulum is particularly striking. Both membrane units are frequently separated from each other by lenticular pseudovacuoles. Mitochondria in protoplasts are swollen and their number is reduced approximately two-fold. Defects are often observed in a nuclear membrane. The perinuclear space is usually extended by lenticular pseudovacuoles. A large number of vacuoles is observed in the basic protoplast cytoplasm. The surface of the protoplasts of all species studied is formed only by a cytoplasmic membrane. A partially digested original cell wall often adheres to protoplasts ofSchizosaccharomyces pombe.     

Metallothionein levels in sperm of various fish species

In the present paper we determined low molecular heavy metal binding protein called metallothionein (MT) in fish spermatozoa sampled from four fish species ( Acipenser baerii, Acipenser ruthenus, Perca fluviatilis and Sander lucioperca ). The spermatozoa samples were analyzed with differential pulse voltammetry DPV (Brdicka reaction). The average content of MT in the fish sperm was 0.64 ± 0.55 μ m . The highest content of MT was determined in spermatozoa of S. lucioperca (0.96 ± 0.86 μ m ), followed by P. fluviatilis (0.88 ± 0.11 μ m ), A. ruthenus (0.57 ± 0.60 μ m ) and A. baerii (0.43 ± 0.25 μ m ). The differences in the content of MT was probably related to the differences in age and perhaps to the health status based on the environmental conditions in which the tested specimens developed while also other still unknown factors may have been involved.     

Pore-forming properties and antibacterial activity of proteins extracted from epidermal mucus of fish.

Among several biological functions, the epidermal mucus of fish may play an important role in host defense, particularly in the prevention of colonization by parasites, bacteria and fungi. In previous work, two hydrophobic proteins of 27 and 31 kDa were isolated from carp mucus. This study identified a strong antibacterial activity (0.16-0.18 microM) well correlated with pore-forming properties. Here this work was extended to other fish species, four fresh water fish and one sea water fish. After a first step of purification, water-soluble and hydrophobic material were separated, and both fractions were analyzed by SDS-PAGE and capillary electrophoresis. Only the hydrophobic component induced pore-forming activity, when reconstituted in planar lipid bilayers. This pore-forming activity was well correlated to a strong antibacterial activity against several bacteria strains. These results suggest that fish secrete antibacterial proteins able to permeabilize the membrane of the target cell and thus act as a defense barrier.     

Seasonal effects on hematological and innate immune parameters in sea bass Dicentrarchus labrax

The temperate aquatic environment is affected by two primary components of season, temperature and photoperiod, during the annual cycle. Many organisms respond to seasonal change physiologically, behaviorally or both. The aim of this study was to investigate the effect of seasonality on cortisol, hematological and innate immune parameters in European sea bass reared under traditional semi-intensive aquaculture. Sea bass (Dicentrarchus labrax) were reared in an outdoor pond and serum cortisol, hematocrit, leucocrit, serum lysozyme activity and total glutathione were bimonthly monitored over a 14-months period. The effect of seasonality was observed for all parameters carried out, with generally higher values in summer and lower in winter. These results could improve the understanding of the influence of seasonal cues on the immune system and hematological parameters in fish in order to optimize the husbandry practices.