Atlantic Cod Piscidin and Its Diversification through Positive Selection

Piscidins constitute a family of cationic antimicrobial peptides that are thought to play an important role in the innate immune response of teleosts. On the one hand they show a remarkable diversity, which indicates that they are shaped by positive selection, but on the other hand they are ancient and have specific targets, suggesting that they are constrained by purifying selection. Until now piscidins had only been found in fish species from the superorder Acanthopterygii but we have recently identified a piscidin gene in Atlantic cod (Gadus morhua), thus showing that these antimicrobial peptides are not restricted to evolutionarily modern teleosts. Nucleotide diversity was much higher in the regions of the piscidin gene that code for the mature peptide and its pro domain than in the signal peptide. Maximum likelihood analyses with different evolution models revealed that the piscidin gene is under positive selection. Charge or hydrophobicity-changing amino acid substitutions observed in positively selected sites within the mature peptide influence its amphipathic structure and can have a marked effect on its function. This diversification might be associated with adaptation to new habitats or rapidly evolving pathogens

Atlantic Cod Piscidin and Its Diversification through Positive Selection

Piscidins constitute a family of cationic antimicrobial peptides that are thought to play an important role in the innate immune response of teleosts. On the one hand they show a remarkable diversity, which indicates that they are shaped by positive selection, but on the other hand they are ancient and have specific targets, suggesting that they are constrained by purifying selection. Until now piscidins had only been found in fish species from the superorder Acanthopterygii but we have recently identified a piscidin gene in Atlantic cod (Gadus morhua), thus showing that these antimicrobial peptides are not restricted to evolutionarily modern teleosts. Nucleotide diversity was much higher in the regions of the piscidin gene that code for the mature peptide and its pro domain than in the signal peptide. Maximum likelihood analyses with different evolution models revealed that the piscidin gene is under positive selection. Charge or hydrophobicity-changing amino acid substitutions observed in positively selected sites within the mature peptide influence its amphipathic structure and can have a marked effect on its function. This diversification might be associated with adaptation to new habitats or rapidly evolving pathogens

Online Analytics for Shrimp Farm Management to Control Water Quality Parameters and Growth Performance

An online analytic service system was designed as a web and a mobile application for shrimp farmers and shrimp farm managers to manage the growth performance of shrimp. The MySQL database management system was used to manage the shrimp data. The Apache Web Server was used for contacting the shrimp database, and the web content displays were implemented with PHP script, JavaScript, and HTML5. Additionally, the program was linked with Google Charts to display data in various graphs, such as bar graphs and scatter diagrams, and Google Maps API was used to display water quality factors that are related to shrimp growth as spatial data. To test the system, field survey data from a shrimp farm in southern Thailand were used. Growth performance of shrimp and water quality data were collected from 13 earthen ponds in southern peninsular Thailand, located in the Surat Thani, Krabi, Phuket, and Satun provinces. The results show that the system allowed administrators to manage shrimp and farm data from the field sites. Both mobile and web applications were accessed by the users to manage the water quality factors and shrimp data. The system also provided the data analysis tool required to select a parameter from a list box and shows the association between water quality factors and shrimp data with a scatter diagram. Furthermore, the system generated a report of shrimp growth for the different farms with a line graph overlay on Google Maps™ in the data entry suite via mobile application. Online analytics for the growth performance of shrimp as provided by this system could be useful as decision support tools for effective shrimp farming

Ubiquitous presence of piscidin-1 in Atlantic cod as evidenced by immunolocalisation

Abstract Background Antimicrobial peptides (AMPs), the natural antibiotics bestowed upon all forms of life, consist of small molecular weight proteins with a broad spectrum antimicrobial activity against a variety of pathogenic microorganisms. Piscidins are one of the AMP families that are imperative for the innate defence mechanisms of teleosts. Atlantic cod, a basal fish belonging to the superorder Paracanthopterygii also possesses multiple piscidin peptides. Two piscidin paralogues (pis1 and pis2) and a novel alternative splice variant of pis2 of this fish were previously described by us. To shed light on other potent roles of these molecules, now we have mapped the distribution of piscidin 1 (Pis1), in different tissues and organs of cod through immunohistochemistry (IHC) employing an affinity purified polyclonal antibody specific to Pis1. Results Various cell types and tissues of Atlantic cod including those from the immune organs of naïve fish are armed with Pis1 peptide. Different types of the blood leucocytes and phagocytic cells among the leucocytes examined gave a relatively strong indication of Pis1 immunopositivity. In addition, other cell types such as hematopoietic cells, epithelial cells and multi-granular cells located in the mucosal and hematopoietic tissues were also Pis1-immunoreactive. More interestingly, chondrocytes appear to produce Pis1 and this is the first report on the presence of an AMP in cartilage tissue of fish. Furthermore, Pis1 immunopositivity was detected in other tissues and organs of naïve fish including neural tissues, exocrine and endocrine glands, compound gland cells, excretory kidney, intestinal and respiratory epithelial cells, swim bladder, skin and hypodermis layer, myosepta, liver, heart, eye and oocytes. Conclusions Pis1 peptide is produced by various cell types located in different tissues and organs of Atlantic cod. It is present in all immune-related organs of naïve fish and the elevated peptide expression following phagocytosis strongly suggest their involvement in innate defence. Further, its widespread occurrence in non-immune tissues and organs of apparently healthy fish implies that piscidin may have other functions in addition to its role as an immune effector molecule.</p

A Novel Beta-Defensin Antimicrobial Peptide in Atlantic Cod with Stimulatory Effect on Phagocytic Activity

<div><p>A novel defensin antimicrobial peptide gene was identified in Atlantic cod, <i>Gadus morhua</i>. This three exon/two intron defensin gene codes for a peptide precursor consisting of two domains: a signal peptide of 26 amino acids and a mature peptide of 40 residues. The mature cod defensin has six conserved cysteine residues that form 1–5, 2–4 and 3–6 disulphide bridges. This pattern is typical of beta-defensins and this gene was therefore named cod beta-defensin (<i>defb</i>). The tertiary structure of Defb exhibits an α/β fold with one α helix and β₁β₂β₃ sheets_. RT-PCR analysis indicated that defb transcripts were present mainly in the swim bladder and peritoneum wall but could also be detected at moderate to low levels in skin, head- and excretory kidneys. In <i>situ</i> hybridisation revealed that <i>defb</i> was specifically expressed by cells located in the swim bladder submucosa and the oocytes. During embryonic development, <i>defb</i> gene transcripts were detectable from the golden eye stage onwards and their expression was restricted to the swim bladder and retina. <i>Defb</i> was differentially expressed in several tissues following antigenic challenge with <i>Vibrio anguillarum</i>, being up-regulated up to 25-fold in head kidney. Recombinant Defb displayed antibacterial activity, with a minimal inhibitory concentration of 0.4–0.8 µM and 25–50 µM against the Gram-(+) bacteria <i>Planococcus citreus</i> and <i>Micrococcus luteus</i>, respectively. In addition, Defb stimulated phagocytic activity of cod head kidney leucocytes <i>in</i><i>vitro</i>. These findings imply that beta-defensins may play an important role in the innate immune response of Atlantic cod.</p></div