Poly-β-hydroxybutyrate administration during early life: effects on performance, immunity and microbial community of European sea bass yolk-sac larvae

The reliable production of marine fish larvae is one of the major bottlenecks in aquaculture due to high mortalities mainly caused by infectious diseases. To evaluate if the compound poly-β-hydroxybutyrate (PHB) might be a suitable immunoprophylactic measure in fish larviculture, its capacity to improve immunity and performance in European sea bass (Dicentrarchus labrax) yolk-sac larvae was explored. PHB was applied from mouth opening onwards to stimulate the developing larval immune system at the earliest possible point in time. Larval survival, growth, microbiota composition, gene expression profiles and disease resistance were assessed. PHB administration improved larval survival and, furthermore, altered the larva-associated microbiota composition. The bacterial challenge test using pathogenic Vibrio anguillarum revealed that the larval disease resistance was not influenced by PHB. The expression profiles of 26 genes involved e.g. in the immune response showed that PHB affected the expression of the antimicrobial peptides ferritin (fer) and dicentracin (dic), however, the response to PHB was inconsistent and weaker than previously demonstrated for sea bass post-larvae. Hence, the present study highlights the need for more research focusing on the immunostimulation of different early developmental stages for gaining a more comprehensive picture and advancing a sustainable production of high quality fry

A study of canniba lism in larvae and post-larvae of sea bass Dicentrarchus labrax (L.1578) under culture conditions. Effects of stocking density and size heterogeneity

The aim of the present study was the investigation upon interindividual competition, with emphasis on cannibalism, in the early developmental stages of sea bass (Dicentrarchus labrax). Three experiments have been carried out with the aim to determine the effects of stocking densities and size heterogeneity on survival, growth and behaviour of sea bass larvae and post-larvae under controlled culture conditions. Experimental populations were reared in cylindroconical tanks of 50-l in a closed water system for the larvae and in a semi-closed system for the post larvae. Larvae were fed with live Brachionus plicatilis replaced successively by Artemia. Post-larvae were fed with live Artemia replaced successively by an adequate industrial dry food. Total length and weight was measured weekly on 30 individuals/tank. Dead fish were counted daily, classified into cannibalised and non-cannibalised fish and photos were taken. Cannibalism was estimated by the number of cannibalised dead fish and the number of missing fish at the end of the experiment. All experimental conditions were tested in triplicate. Results indicated that stocking density (50, 100, 150, 200 larvae/l) did not effect survival and larval growth performance. Most deaths were recorded before d10 and mainly related to problems of exogenous feed ingestion and lipid drop absorption. At this developmental stage no cannibalism was observed. In contrast, initial stocking density and size heterogeneity effect the survival and the extent of cannibalism of reared post-larvae. Survival was significantly higher in the lower densities (5 and 10 post-larvae./l) than in the higher densities (15 and 20 post-larvae./l) than in the higher densities. Also, the percentage of missing fish and thus cannibalism was significantly higher in the highest density. Three different size heterogeneity of post-larvae were tested : 1. Natural heterogeneity, 2. Minimum heterogeneity, and 3. Maintenance of the homogeneity. Survival was significantly higher in the populations with the modified homogeneity compared to all others. A positive correlation between coefficient of variation of weight and cannibalism was observed. In post-larvae experiments, cannibalism was detected on all dead fish in the form of heavy damage to dorsal, anal and mainly to the caudal fin and was observed on all occasions even after food was given. Cannibals attacked their prey from the back catching it by the caudal fin, swallowing it slowly or releasing it.Η παρούσα εργασία είχε σαν στόχο τη μελέτη του ενδοπληθυσμιακού ανταγωνισμού με έμφαση στον κανιβαλισμό που αναπτύσσεται στα πρώτα αναπτυξιακά στάδια εκτροφής του λαβρακιού (Dicentrarchus labrax). Σχεδιάστηκαν τρία πειράματα με σκοπό να ελεγχθεί η επίδραση της ιχθυοφόρτισης και της ετερογένειας του μεγέθους στην επιβίωση, ανάπτυξη και συμπεριφορά των νυμφών και μετανυμφών του λαβρακιού σε συνθήκες εκτροφής. Τα πειράματα πραγματοποιήθηκαν στις εγκαταστάσεις του Ινστιτούτου Θαλάσσιας Βιολογίας Κρήτης, σε κυλινδροκωνικές πολυεστερικές δεξαμενές (50-l) κάτω από ελεγχόμενες συνθήκες εκτροφής. Η διατροφή των νυμφών γινόταν με ζωντασνούς οργανισμούς, αρχικά με Brachionus plicatilis οι οποίοι σταδιακά αντικαταστάθηκαν από ναύπλιους και μεταναύπλιους Artemia. Η διατροφή των μετανυμφών γινόταν αρχικά με ναύπλιους και μεταναύπλιους Artemia οι οποίοι σταδιακά αντικαταστάθηκαν με βιομηχανική τροφή. Η καταγραφή του ατομικού βάρους και του ολικού μήκους των ψαριών γινόταν σε εβδομαδιαία βάση, σε δείγμα 30 ατόμων/δεξαμενή. Η καταμέτρηση των νεκρών ατόμων και ο διαχωρισμός τους σε κανιβαλισμένα ή μη κανιβαλισμένα γινόταν καθημερινά. Επιπλέον, γινόταν φωτογραφική αποτύπωση ατόμων που έφεραν ίχνη κανιβαλιστικών επιθέσεων ή δυσμορφιών. Η ένταση του κανιβαλισμού εκτιμήθηκε από τον αριθμό των νεκρών ατόμων που βρέθηκαν να φέρουν ίχνη κανιβαλιστικών επιθέσεων και από τον αριθμό των «χαμένων» ατόμων στο τέλος των πειραμάτων. Όλες οι πειραματικές συνθήκες δοκιμάστηκαν εις τριπλούν. Η ιχθυοφόρτιση (50, 100, 150, 200 larvae/l) δεν φαίνεται να επηρεάζει την επιβίωση και αύξηση των νυμφών του λαβρακιού. Το μεγαλύτερο ποσοστό της θνησιμότητας παρατηρήθηκε τις πρώτες δέκα ημέρες και αποδόθηκε κυρίως σε προβλήματα που σχετίζονται με την έναρξη της ετερότροφης ζωής των νυμφών και σε προβλήματα απορρόφησης της σταγόνας λιπιδίων. Σε αυτό το αναπτυξιακό στάδιο δεν παρατηρήθηκε κανιβαλισμός. Αντίθετα, η ιχθυοφόρτιση και η ετερογένεια του μεγέθους επηρεάζουν την επιβίωση και την ένταση του κανιβαλισμού των μετανυμφών σε συνθήκες εκτροφής.. Η επιβίωση ήταν στατιστικά σημαντικά μεγαλύτερη στις χαμηλές ιχθυοφορτίσεις (5 and 10 post-larvae./l) σε σύγκριση με την επιβίωση στις υψηλές ιχθυοφορτίσεις (15 and 20 post-larvae./l). Επιπλέον, το ποσοστό των «χαμένων» ατόμων στο τέλος του πειράματος, και επομένως η ένταση του κανιβαλισμού, ήταν στατιστικά σημαντικά μεγαλύτερο στην υψηλότερη ιχθυοφόρτιση. Οι τρεις διαφορετικές συνθήκες ετερογένειας που εξετάστηκαν ήταν: 1. Φυσική ετερογένεια, 2. Ελάχιστη ετερογένεια, 3. Διατήρηση της ομοιογένειας.. Η επιβίωση ήταν στατιστικά σημαντικά υψηλότερη στους πληθυσμούς στους οποίους γινόταν τακτική διαλογή μεγέθους. Επιπλέον, παρατηρήθηκε θετική συσχέτιση του συντελεστή μεταβλητότητας του βάρους με τον κανιβαλισμό. Κανιβαλισμός παρατηρήθηκε και στα δύο πειράματα με τις μετανύμφες του λαβρακιού. Η θνησιμότητα αποδόθηκε εξ' ολοκλήρου στον κανιβαλισμό και τα νεκρά άτομα ήταν τραυματισμένα στο ραχιαίο, εδρικό και κυρίως στο ουραίο πτερύγιο Οι θηρευτές συλλαμβάνανε την λεία τους από το ουραίο πτερύγιο και την καταβρόχθιζαν αργά

Survival, growth and feeding in early life stages of European sea bass (<i>Dicentrarchus labrax</i>) intensively cultured under different stocking densities

Two experiments were conducted in triplicate in order to study the effect of stocking densities on survival (highlighting sibling cannibalism), growth and feeding of intensively cultured sea bass larvae (50, 100, 150 and 200 fish l(-1)) and post-larvae (5, 10, 15 and 20 fish l(-1)). Experimental populations were reared under controlled conditions in 50-l cylindroconical tanks. Dead fish were counted daily and classified into cannibalised and non-cannibalised. Total length and weight were measured weekly. Results indicate that stocking density did not affect survival and growth of larvae. No cannibalistic phenomena were observed at this stage. On the other hand, survival of post-larvae was higher at 5 and 10 fish l(-1) than at 15 and 20 fish l(-1), while growth performance fluctuated between the lowest value recorded in the group of 10 fish l(-1) and the highest value in that of 5 fish l(-1). Feed intake in post-larvae was independent of stocking density. Cannibalism was the main cause of death in post-larvae. Two types of cannibalism were detected: type I, attack from tail (observed at the beginning of this stage) and type II, attack from head (observed at the end of the stage)

Salts of Clopidogrel: Investigation to Ensure Clinical Equivalence: A 12-Month Randomized Clinical Trial

Background: In the present clinical trial, we compared the efficacy and safety of the generic clopidogrel besylate (CB) with the innovator clopidogrel hydrogen sulfate (CHS) salt in patients eligible to receive clopidogrel. Methods: A prospective 2-arm, multicenter, open-label, phase 4 clinical trial. Consecutive patients (n = 1864) were screened and 1800 were enrolled in the trial and randomized to CHS or CB. Primary efficacy end point was the composite of myocardial infarction, stroke, or death from vascular causes, and primary safety end point was rate of bleeding events as defined by Bleeding Academic Research Consortium criteria. Results: At 12-month follow-up, no differences were observed between CB (n = 759) and CHS (n = 798) in primary efficacy and safety end points (age, sex, history of percutaneous coronary intervention adjusted odds ratio [OR], 0.70; 95% confidence interval [CI], 0.41-1.21 and OR, 0.81; 95% CI, 0.51-1.29, respectively) between CHS and CB. Analyses of efficacy and safety in subgroups that were defined according to the qualifying diagnosis revealed that there was no difference between CHS and CB. Conclusion: The efficacy and safety of CB administered for 12 months for the secondary prevention of atherothrombotic events are similar to that of CHS

Generic Clopidogrel Besylate in the Secondary Prevention of Atherothrombotic Events: A 6-month Follow-up of a Randomised Clinical Trial

Background: The aim of the present interim analysis was to compare the clinical efficacy and safety of the generic clopidogrel besylate (CB) with the innovator clopidogrel hydrogen sulphate (CHS) salt in patient groups eligible to receive clopidogrel. Methods: A 2-arm, multicenter, open-label, phase IV clinical trial. Consecutive patients (n=1,864) were screened and 1,800 were enrolled in the trial and randomized to CHS (n=759) or CB (n=798). Primary efficacy end point was the composite of myocardial infarction, stroke or death from vascular causes. Primary safety end point was the rate of bleeding events as defined by Bleeding Academic Research Consortium (BARC) criteria. Results: At 6-months follow-up no differences were observed between CB and CHS in primary efficacy end point (OR, 0.80; 95% CI, 0.37 to 1.71; p=0.57). Rates of BARC-1,-2,-3a and -5b bleeding were similar between the two study groups whereas no bleeding events according to BARC-3b, -3c, -4 and -5a were observed in either CHS or CB group. Conclusion: The clinical efficacy and safety of the generic CB were similar to those of the innovator CHS salt, thus this generic clopidogrel formulation can be routinely used in the secondary prevention of atherothrombotic events for a period of at least 6 months. (Salts of Clopidogrel: Investigation to ENsure Clinical Equivalence, SCIENCE study Clinical Trials.gov Identifier: NCT02126982)