Salinity reduction benefits European eel larvae: Insights at the morphological and molecular level

European eel (Anguilla anguilla) is a euryhaline species, that has adapted to cope with both, hyper- and hypo-osmotic environments. This study investigates the effect of salinity, from a morphological and molecular point of view on European eel larvae reared from 0 to 12 days post hatch (dph). Offspring reared in 36 practical salinity units (psu; control), were compared with larvae reared in six scenarios, where salinity was decreased on 0 or 3 dph and in rates of 1, 2 or 4 psu/day, towards iso-osmotic conditions. Results showed that several genes relating to osmoregulation (nkcc2α, nkcc2β, aqp1dup, aqpe), stress response (hsp70, hsp90), and thyroid metabolism (thrαA, thrαB, thrβB, dio1, dio2, dio3) were differentially expressed throughout larval development, while nkcc1α, nkcc2β, aqp3, aqp1dup, aqpe, hsp90, thrαA and dio3 showed lower expression in response to the salinity reduction. Moreover, larvae were able to keep energy metabolism related gene expression (atp6, cox1) at stable levels, irrespective of the salinity reduction. As such, when reducing salinity, an energy surplus associated to reduced osmoregulation demands and stress (lower nkcc, aqp and hsp expression), likely facilitated the observed increased survival, improved biometry and enhanced growth efficiency. Additionally, the salinity reduction decreased the amount of severe deformities such as spinal curvature and emaciation but also induced an edematous state of the larval heart, resulting in the most balanced mortality/deformity ratio when salinity was decreased on 3 dph and at 2 psu/day. However, the persistency of the pericardial edema and if or how it represents an obstacle in further larval development needs to be further clarified. In conclusion, this study clearly showed that salinity reduction regimes towards iso-osmotic conditions facilitated the European eel pre-leptocephalus development and revealed the existence of highly sensitive and regulated osmoregulation processes at such early life stage of this species

The Korowai Framework: Assessing GE through the Values the ART Confederation Associates with Ngarara

The aim of this thesis is to assess genetic engineering (GE) through the values that the Confederation of Te Ati Awa, Ngati Raukawa ki te tonga and Ngati Toarangatira (the ART Confederation) associates with ngarara. The Korowai Framework was developed to conduct this assessment. Interviews were conducted with 14 participants from across the ART Confederation on the values they associate with ngarara and their interpretations of GE. The values associated with ngarara that were identified in the interviews, were used constitute the kaupapa of the Korowai Framework. The key values identified are: mauri, whakapapa, tohu, tapu, and kaitiakitanga. It emerged from the interviews that ngarara appeal to us to be conscious of our intricately bound connection to and dependency on living systems. The assessment through the Korowai Framework found that the outcomes of GE do not uphold the values associated with ngarara. Participants articulated significant concerns that GE confounds the ART Confederation's control over their relationship with the world around them. This thesis has demonstrated that the Korowai Framework can be used as a tool for the Confederation to get to the decision making table with a comprehensive evidence based understanding of the people's position on GE from which they can negotiate. It demonstrates that robust and legitimate assessment of GE can be conducted using theories, methodologies, kaupapa, tikanga, and frameworks that are specific to the ART Confederation

Etude biochimique et morphologique de l'adaptation de l'intestin grele au taux et a la nature de l'apport azote du regime, chez le rat

SIGLEINIST T 77274 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc

Effect of nutrition on marine fish development and quality

Fish larval stage represents a transitional period in which both ontogeny and growth cause substantial changes in structure, physiology, size and morphology. These last twenty years, most of the studies on marine fish larvae development have dealt with the ontogeny and functioning of the digestive tract in order to overcome bottlenecks in larvae culture and weaning processes (switch from live preys to compound diet feeding sequence). These studies clearly demonstrated that fish larvae are not faced to physiological or digestive deficiencies (Zambonino Infante and Cahu, 2001) although they hatch with very immature organs compared to juveniles. More recently, the possible impact of nutritional events occurred during early larvae development stages were considered by different several research groups (Zambonino Infante and Cahu, 2007). Teleosts have similar basic mechanisms of organ development but differences can be found in the relative timing of the ontogeny. For example, the same main morphological and cellular changes occur during the ontogeny of the gastrointestinal tract in Teleost but the timing of the events will be more or less advanced depending on the natural environment temperature (tropical, temperate or cold) of the considered species (Zambonino Infante and Cahu, 2001). Several abiotic and biotic factors, such as water temperature, food availability and composition during early life stages influence the time in organ development and its associated physiological functions. The potential impact of early nutrition on larvae morphogenesis has been probably the most studied these last 5 years, mainly because morphogenesis is the most visible consequence, and therefore the most economically detrimental to aquaculture industry. However, other potential changes, less visible, that could also occurred are more and more considered since they will determine the nutritional and physiological performances of a fish, and therefore its ability to deal with challenges during its subsequent life (Fuiman, 1997). This chapter aims to give an overview of the main developmental events in fish larvae, and describe the impact of early nutrition on the developmental processes that condition the future juvenile potentials

Partial substitution of di- and tripeptides for native proteins in sea bass diet improves dicentrarchus labrax larval development

To determine whether incorporation of peptides into diets can improve larval development, sea bass (Dicentrarchus labrax) larvae were fed for 21 d one of three isonitrogenous, isoenergetic semipurified diets in which enzymatic hydrolysate (75% di- and tripeptides) of fish meal proteins was substituted for 0, 20 or 40% of native fish meal proteins. Growth and survival were significantly greater (P < 0.05) in larvae fed peptide diets compared to those fed only native protein, with the best performance exhibited by those fed the 20% level of peptides. Chymotrypsin activity was much higher in groups fed peptide diets compared to that fed all native protein (P < 0.001), indicating a greater proteolytic capacity of the pancreas. At the intestinal level, activities of the brush border enzymes, aminopeptidase, maltase and gamma-glutamyl transpeptidase, increased with age while the cytosolic enzyme, leu-ala peptidase, decreased with age (P < 0.001). These changes in enzymatic activities correspond to the normal development of intestinal digestion. This development occurred earlier in the group fed 20% peptide-substituted diet than in the two other groups. The better larval performances observed in groups fed diets containing peptides can be related to the enhanced proteolytic capacity of the pancreas and the earlier development of intestinal digestion

Effect of dietary phospholipid level and phospholipid:neutral lipid value on the development of sea bass ( Dicentrarchus labrax ) larvae fed a compound diet

International audienceThe aim of the study was to determine the influence of dietary phospholipid concentration on survival and development in sea bass ( Dicentrarchus labrax ) larvae. Larvae were fed from day 9 to day 40 post-hatch with an isoproteic and isolipidic formulated diet with graded phospholipid levels from 27 to 116 g/kg DM and different phospholipid:neutral lipid values. The best growth (32 mg at the end of the experiment) survival (73 %) and larval quality (only 2% of malformed larvae) were obtained in the larvae fed the diet containing 116 g phospholipid/kg DM ( P < 0·05). These results were related to the amount of phosphatidylcholine and phosphatidylinositol included in this diet (35 and 16 g/kg respectively). Amylase, alkaline phosphatase and aminopeptidase N activities revealed a proper maturation of the digestive tract in the two groups fed the highest phospholipid levels. Regulation of lipase and phospholipase A2 by the relative amount of their substrate in the diet occurred mainly at the transcriptional level. The response of pancreatic lipase to dietary neutral lipid was not linear. As in mammals 200 g triacylglycerol/kg diet seems to represent a threshold level above which the response of pancreatic lipase is maximal. The response of phospholipase A2 to dietary phospholipid content was gradual and showed a great modulation range in expression. Sea bass larvae have more efficient capacity to utilize dietary phospholipid than neutral lipids. For the first time a compound diet sustaining good growth, survival and skeletal development has been formulated and can be used in total replacement of live prey in the feeding sequence of marine fish larvae

Fish facing global change: are early stages the lifeline?

International audienceThe role of phenotypic plasticity in the acclimation and adaptive potential of an organism to global change is not currently accounted for in prediction models. The high plasticity of marine fishes is mainly attributed to their early stages, during which morphological, structural and behavioural 'functions are particularly sensitive to environmental constraints. This developmental plasticity can determine later physiological performances and fitness, and may further affect population dynamics and ecosystem functioning. This review asks the essential question of what role early stages play in the ability of fish to later cope with the effects of global change, considering three key environmental factors (temperature, hypoxia and acidification). After having identified the carry-over effects of early exposure reported in the literature, we propose areas that we believe warrant the most urgent attention for further research to better understand the role of developmental plasticity in the responses of marine organisms to global change

Rapport d’activité 2018-2019 UNITE RBE/PFOM. Physiologie Fonctionnelle des Organismes Marins

Activités scientifiques 2018-201