Crustins are antibacterial proteins of ca 7-14 kDa with a characteristic four disulphide corecontaining whey acidic protein (WAP) domain, expressed by the circulating haemocytes of crustaceans.Over 50 crustin sequences have been now reported from a variety of decapods, including crabs, lobsters, shrimp and crayfish. Three main types seem to occur but all possess a signal sequence at the amino terminus and a WAP domain at the carboxyl end. Differences between types lie in the structure of the central region. Those crustins purified as the native protein or expressed recombinantly all kill Gram-positive bacteria, and gene studies have shown that they are constitutively expressed, often at high levels, but show no consistent patterns of change in expression following injection of bacteria. This variable response to infection is enigmatic but indicates that these proteins could perform additional functions, perhaps as immune regulators in recovery from wounding, trauma or physiological stress.Prof Kenneth Soderhall Co-Editor in Chief Developmental and Comparative Immunology Dear Kenneth I attach the revised manuscript for the invited review, Crustins: enigmatic WAP domaincontaining antibacterial proteins from crustaceans, for which all the referees comments have been addressed. Below is a summary of changes made.1. Two of the reviewers have issues with the SS tree (formerly Fig 2), with reviewer 2 making the point that the functional WAP domain will more usefully indicate relationships rather than the SS. We do not concur with the comment that the signal sequence (SS) tree is unnecessary but do accept that its placement in the article could be better and that it could be more fully discussed. Importantly, the SS radiation tree did not drive the 3-type classification, rather it was led by the overall domain organisation of the various types that we judged, from our starting definition, to be within the crustin 'family'. The region of variation is mainly in the 'central' region of the molecule, ie between the SS and WAP domain. We constructed the SS and WAP domain trees to test if the suggested classification was supported, independently by phylogenies within these regions. We believe that they do and the inclusion of both trees, rather than just a tree for the WAP domain, makes the case for the classification of crustins into Types I, II or III, even stronger. We have therefore retained the SS radiation tree but discuss it more fully in the section on 'Relationships' (new pages 11 & 12) rather than its former position. We prefer not to add species identifiers to the as these will make it very 'busy' and untidy. We feel that Accession numbers are more appropriate than species names. Please note we have slightly modified the annotations by leaving ambiguous sequences out of the clusters marked by dotted or dashed lines.2. Referee 1 correctly points out that the argument (beginning in the last paragraph on pg 6 and continued on pg 7in the original m/s) that the signal sequence is probably not involved in crust...

No abstract

Skin exudates of rainbow trout contain a potent 13.6 kDa anti-microbial protein which, from partial internal amino acid sequencing, peptide mass fingerprinting, matrix-associated laser desorption/ionization MS and amino acid analysis, seems to be histone H2A, acetylated at the N-terminus. The protein, purified to homogeneity by ion-exchange and reversed-phase chromatography, exhibits powerful anti-bacterial activity against Gram-positive bacteria, with minimal inhibitory concentrations in the submicromolar range. Kinetic analysis revealed that at a concentration of 0.3 microM all test bacteria lose viability after 30 min incubation. Weaker activity is also displayed against the yeast Saccharomyces cerevisiae. The protein is salt-sensitive and has no haemolytic activity towards trout erythrocytes at concentrations below 0.3 microM. Reconstitution of the protein in a planar lipid bilayer strongly disturbs the membrane but does not form stable ion channels, indicating that its anti-bacterial activity is probably not due to pore-forming properties. This is the first report to show that, in addition to its classical function in the cell, histone H2A has extremely strong anti-microbial properties and could therefore help contribute to protection against bacterial invasion.

No abstract

Enhanced production of high quality and healthy fry is a key target for a successful and competitive expansion of the aquaculture industry. Although large quantities of fish larvae are produced, survival rates are often low or highly variable and growth potential is in most cases not fully exploited, indicating significant gaps in our knowledge concerning optimal nutritional and culture conditions. Understanding the mechanisms that control early development and muscle growth are critical for the identification of time windows in development that introduce growth variation, and improve the viability and quality of juveniles. This literature review of the current state of knowledge aims to provide a framework for a better understanding of fish skeletal muscle ontogeny, and its impact on larval and juvenile quality as broadly defined. It focuses on fundamental biological knowledge relevant to larval phenotype and quality and, in particular, on the factors affecting the development of skeletal muscle. It also discusses the available methodologies to assess growth and larvae/juvenile quality, identifies gaps in knowledge and suggests future research directions. The focus is primarily on the major farmed non-salmonid fish species in Europe that include gilthead sea bream, European sea bass, turbot, Atlantic cod, Senegalese sole and Atlantic halibut.

No abstract

SUMMARYIn Senegalese sole (Solea senegalensis Kaup), growth is negatively correlated to dietary lipid levels. To understand the molecular basis of this effect a molecular toolbox of 12 genes, including fgf6, fst, mstn1, myf5, mrf4, myod1, myod2, myog, myHC, mylc2, igf1r and insr, was developed. The expression profiles of these genes were investigated in white muscle and liver of fish fed with three dietary lipid levels (4%, 12% and 20%). The expression of igf-I and igf-II was also examined. MRFs and myosins were only expressed in the muscle and, except for myf5, the general trend was a decrease in expression with an increase in dietary lipids. Fgf6 was identified for the first time in liver and its expression augmented in hepatic tissues with increasing dietary lipid levels. A similar tendency was observed for mstn1 and igf-I. The opposite was observed for igf1r expression in muscle and liver. Myog, mrf4, mylc2 and igf1r were highly correlated with growth and nutrient utilisation indices. In addition to its practical implications, this work provides a valuable contribution towards our understanding of the genetic networks controlling growth in teleosts. Supplementary material available online at

Host-associated microbiota undergoes a continuous transition, from the birth to adulthood of the host. These developmental stage-related transitions could lead to specific microbial signatures that could impact the host biological processes. In this study, the succession of early-life and intestinal bacterial communities of Atlantic salmon (starting from embryonic stages to 80-week post hatch; wph) was studied using amplicon sequencing of 16S rRNA. Stage-specific bacterial community compositions and the progressive transitions of the communities were evident in both the early life and the intestine. The embryonic communities showed lower richness and diversity (Shannon and PD whole tree) compared to the hatchlings. A marked transition of the intestinal communities also occurred during the development; Proteobacteria were dominant in the early stages (both embryonic and intestinal), though the abundant genera under this phylum were stage-specific. Firmicutes were the most abundant group in the intestine of late freshwater; Weissella being the dominant genus at 20 wph and Anaerofilum at 62 wph. Proteobacteria regained its dominance after the fish entered seawater. Furthermore, LEfSe analysis identified genera under the above - mentioned phyla that are significant features of specific stages. The environmental (water) bacterial community was significantly different from that of the fish, indicating that the host is a determinant of microbial assemblage. Overall the study demonstrated the community dynamics during the development of Atlantic salmon.