The Physiology of Smoltification and Seawater Adaptation in Rainbow Trout

Seawater-transferred rainbow trout (Oncorhynchus mykiss) has become an attractive aquaculture product in recent years. Industrial interest is mainly due to its resistance to infectious pancreatic necrosis and its adaptability to brackish water, which allows farming in otherwise unexploited locations. However, most practices for the aquaculture of this species have been imported from Atlantic salmon (Salmo salar) without evidence data supporting their suitability for the species. These include protocols to induce their preadaptation to seawater (smoltification). As a result, following seawater transfer, large numbers of fish die (around 10%) or become growth-stunted (GS; 10-60%). Therefore, species-specific rearing protocols and seawater-readiness biomarkers are needed. In the present PhD thesis, the effects of different photoperiod and temperature protocols for rearing in freshwater were assessed on the development of smoltification traits and subsequent seawater performance. This was achieved by using an array of molecular tools to measure osmoregulation-, growth- and haematopoiesis-related genes, proteins and hormones. Moreover, the discovery of potential seawater-readiness biomarkers and the study of smoltification, seawater adaptation and GS fish development were performed using several mass spectrometry proteomic and lipidomic approaches. Results suggest that winter light signals are inadvisable for the species, while all tested summer signals produced similar good results. Moreover, increased temperature protocols not only failed to improve smoltification and growth but potentially compromised the immune system of the fish. Overall, continuous light seems an advisable light regime, irrespective of temperature. Moreover, new promising potential biomarkers for seawater-readiness were identified using proteomics, while also suggesting a previously unknown role of these proteins in smoltification and seawater adaptation. Finally, GS development was shown to be related to low insulin-like growth factor 1 levels following seawater transfer. Moreover, other related factors to the phenotype were higher stress levels, possibly caused by bullying by bigger fish, and hepatic anomalies related to oxidative stress

La col·lecció d’exvots de l’església de Santa Maria la Major

[cat]Un exvot és un objecte ofert a una divinitat en compliment d’una petició o d’un benefici. A Mallorca fou tradicional l’oferiment de petites estatuetes, joies, o altres objectes d’ús privat per agrair el guariment de la malalties o l’alliberament d’una desgràcia. També era costum oferir el pes en cera, realitzar figuretes de retall o de planxa de plata, o bé en forma humana o bé representant els membres afavorits o agraciats. Amb aquesta comunicació volem donar a conèixer i posar en valor la col·lecció d’exvots que es conserva a l’església de Santa Maria la Major.[eng]An votive offering is an object given to a god in fulfillment of a request or a benefit. In Mallorca was traditional the offering of small statues, jewels or other objects for private use to thank for the cure of diseases and the protection of a misfortune. It was also common to offer figures of wax or silver, in human form or favored or graceful parts. With this communication we want to make known and value the collection of votive offerings of the church of Santa Maria la Major

Les teules pintades a Inca, una nova troballa

Fins entrat el segle XX l’arquitectura popular era el tipus de construcció més significativa i predominant en el conjunt de Mallorca. En aquest àmbit, les teules pintades es convertiren en un element destacat de dita arquitectura. Amb el pas del temps esdevenen una manifestació artística arrelada a l’illa i constitueixen avui un element característic del nostre patrimoni cultural. L’objectiu d’aquesta comunicació és documentar, posar en valor i donar a conèixer les teules pintades en el cas d’Inca. Aquest treball ve motivat principalment a partir d’una nova troballa de teules, la primera realitzada a l’interior del nucli urbà.Even into the twentieth century popular architecture was the most significant type of construction and predominant in the whole of Mallorca. In this area, painted tiles, became a prominent element of this architecture. With the passage of time become an art form rooted on the island and now constitute a characteristic element of our cultural heritage. The purpose of this communication is to document, highlight and publicize painted tiles in the case of Inca. This work is motivated primarily from a new discovery tiles, first performed inside the town

Arquitectura industrial d'Inca, una aproximació al patrimoni conservat i desaparegut

[cat] El patrimoni industrial és un terme ampli, i més aviat recent, emprat per referir-se a tots els béns generats arran de la industrialització. Aquests béns poden ser immobles, mobles o immaterials i, degut al seu caràcter utilitari, ha estat difícil que rebin el reconeixement que mereixen. Per aquest motiu avui dia alguns exemples han desaparegut o es troben en un estat d'abandonament. La present comunicació pretén analitzar la situació actual en què es troba a Inca el patrimoni industrial, més en concret pel que fa a la recuperació i rehabilitació dels béns immobles. S’avaluen així les diferents iniciatives impulsades en aquest sentit i el grau d'encert de cada una de les intervencions.[eng] Industrial Heritage is a broad and recent term, it is used to refer to all the goods generated from industrializacion. This goods can be material or immaterial, and because their utilitarian nature they have not received the recognition they deserve. For this reason today some examples have disappeared or are in a state of abandonment. This paper aims to analyze the current situation of Industrial Heritage of Inca, especially about the recovery and rehabilitation of their buildings. Evaluating the different initiatives promoted in this matter and their success

L’obra arquitectònica de Guillem Reynés Font a Inca

La present comunicació se centra en l’estudi de l’activitat arquitectònica duita a terme per l’arquitecte Guillem Reynés i Font a la ciutat d’Inca. Com a conseqüència del gran nombre i diversitat d’obres projectades pel dit arquitecte, aquestes s’han agrupat en tipologies arquitectòniques: civil, religiosa, militar i industrial. En l’esmentat context, situarem aquestes construccions en la seva trajectòria com a arquitecte, i en el modernisme balear.The present study focuses on the architectural activity carried out by the architect Guillem Reynés Font in Inca. As a result of the large number and the diversity of works designed by the architect, these have been grouped in architectural styles: civil, religious, military and industrial. In this context, we will place these buildings in his career as an architect, and in the balearic modenism style

Plasma proteome profiling of freshwater and seawater life stages of rainbow trout (Oncorhynchus mykiss)

The sea-run phenotype of rainbow trout (Oncorhynchus mykiss), like other anadromous salmonids, present a juvenile stage fully adapted to life in freshwater known as parr. Development in freshwater is followed by the smolt stage, where preadaptations needed for seawater life are developed making fish ready to migrate to the ocean, after which event they become post-smolts. While these three life stages have been studied using a variety of approaches, proteomics has never been used for such purpose. The present study characterised the blood plasma proteome of parr, smolt and post-smolt rainbow trout using a gel electrophoresis liquid chromatography tandem mass spectrometry approach alone or in combination with low-abundant protein enrichment technology (combinatorial peptide ligand library). In total, 1,822 proteins were quantified, 17.95% of them being detected only in plasma post enrichment. Across all life stages, the most abundant proteins were ankyrin-2, DNA primase large subunit, actin, serum albumin, apolipoproteins, hemoglobin subunits, hemopexin-like proteins and complement C3. When comparing the different life stages, 17 proteins involved in mechanisms to cope with hyperosmotic stress and retinal changes, as well as the downregulation of nonessential processes in smolts, were significantly different between parr and smolt samples. On the other hand, 11 proteins related to increased growth in post-smolts, and also related to coping with hyperosmotic stress and to retinal changes, were significantly different between smolt and post-smolt samples. Overall, this study presents a series of proteins with the potential to complement current seawater-readiness assessment tests in rainbow trout, which can be measured non-lethally in an easily accessible biofluid. Furthermore, this study represents a first in-depth characterisation of the rainbow trout blood plasma proteome, having considered three life stages of the fish and used both fractionation alone or in combination with enrichment methods to increase protein detection

Liver colour scoring index, carotenoids and lipid content assessment as a proxy for lumpfish (Cyclopterus lumpus L.) health and welfare condition

Ensuring lumpfish health and welfare in salmon farms is vital to reduce the high mortality rates reported and to guarantee a high delousing efficiency. Recent observations of farmed lumpfish livers have shown colours ranging from pale (colours 1 and 2), through bright orange (colours 3 and 4), to dark reddish-brown (colours 5 and 6), some of which may be related to welfare condition. To characterize the status of lumpfish deployed in four Faroese salmon farms, several welfare indicators were assessed: a weight-length relationship, scoring of external physical damage, and after dissection, stomach content and liver colour scoring. Liver samples were weighed, stored and analysed for lipid content, lipid classes, total pigments, fatty acid profile and histopathology to explain the differences between the mentioned liver colours. Bright orange livers, liver colours 3 and 4, were related to increased levels of carotenoid pigments rather than levels of lipids and appear to reflect good fish welfare. However, dark reddish-brown colours, liver colours 5 and 6, were associated with very low levels of triacyl glycerides in the liver, indicating use of lipid reserves and poor welfare condition. Histopathology confirmed that the dark reddish-brown livers, liver colours 5 and 6, formed a distinct group. Thus, liver colour was shown to be a good welfare indicator and should be monitored in farms

Polarized trout epithelial cells regulate transepithelial electrical resistance, gene expression, and the phosphoproteome in response to viral infection

The burden of disease is a major challenge in aquaculture production. The fish gill characterised with a large surface area and short route to the bloodstream is a major environmental interface and a significant portal of entry for pathogens. To investigate gill responses to viral infection the salmonid gill cell line RTgill-W1 was stimulated with synthetic dsRNA and the salmonid alphavirus subtype 2 (SAV-2). Epithelial integrity in polarized cells measured as transepithelial electrical resistance (TER) immediately increased after stimulation with the synthetic dsRNA, polyinosinic:polycytidylic acid (poly(I:C)). In parallel, tight junction and gene expression of innate immune activation markers was modulated in response to poly(I:C). The SAV-2 virus was found to replicate at a low level in RTgill-W1 cells where TER was disturbed at an early stage of infection, however, gene expression related to tight junction regulation was not modulated. A strong poly(I:C)-driven antiviral response was observed including increases of Rig-like receptors (RLRs) and interferon stimulating genes (ISGs) mRNAs. At the level of signal transduction, poly(I:C) stimulation was accompanied by the phosphorylation of 671 proteins, of which 390 were activated solely in response to the presence of poly(I:C). According to motif analysis, kinases in this group included MAPKs, Ca2+/calmodulin-dependent kinase (CaMK) and cAMP-dependent protein kinase (PKA), all reported to be activated in response to viral infection in mammals. Results also highlighted an activation of the cytoskeletal organisation that could be mediated by members of the integrin family. While further work is needed to validate these results, our data indicate that salmonid gill epithelia mount a significant response to viral infection that is likely crucial to disease progression. In vitro cell culture can facilitate both a deeper understanding of the anti-viral response in fish and open novel therapeutic avenues for fish health management in aquaculture

Effects of different photoperiod regimes on the smoltification and seawater adaptation of seawater-farmed rainbow trout (Oncorhynchus mykiss): Insights from Na+, K+-ATPase activity and transcription of osmoregulation and growth regulation genes

Photoperiod is thought to be the main zeitgeber that induces smoltification in salmonids. However, its effects on the smoltification of rainbow trout (Oncorhynchus mykiss) are not fully understood and no published data documents the effects of the photoperiod regime currently used commercially, continuous light (LL). The present study compared the effect of four different photoperiod regimes (i.e. advanced phase photoperiod (APP), delayed phase photoperiod (DPP), LL and simulated natural photoperiod (SNP)) on the smoltification and growth of juvenile rainbow trout during their freshwater phase of winter-spring and the following summer post smolt phase. Smoltification was evaluated by monitoring gill Na+,K+–ATPase (NKA) activity and transcription of NKA α-subunit isoforms 1a and 1b, and Na+,K+,2Cl− cotransporter 1a. Growth was measured as specific growth rate of both length and weight, and through molecular growth proxies such as the levels of circulating insulin-like growth factor 1 (IGF-I) in plasma and transcription of igf-I, igf binding protein 1b (igfbp1b), growth hormone receptor 1 (ghr1) and cathepsin L (ctsl) in the liver. Results indicate that APP induces a longer smolt window and higher levels of plasma IGF-I in both freshwater and seawater (two months post transfer), while DPP led to a shorter smolt window, lower plasma IGF-I levels in freshwater and seawater, an earlier decrease in liver igf-I and ctsl transcription in freshwater (as seen by modelling over time) and lower specific growth rate in freshwater. The transcription analysis of osmoregulatory genes complemented NKA activity and allowed for the detection of a transient response to light and of differences between the osmoregulatory capacity of parr and desmolted fish. Furthermore, an upregulation of the liver transcription of igf-I, ghr1 and ctsl was found in all treatments during the smolt window, which corresponded to the periods with highest growth. Finally, both plasma IGF-I and liver igf-I in seawater were found to be significantly correlated to fish growth in seawater. However, our data did not show that plasma IGF-I prior to seawater transfer could be used as a reliable predictor of growth in seawater. Overall, and especially when compared with other salmonid species, photoperiod seems to be a weaker inducer of smoltification in rainbow trout, according to the parameters that were tested, suggesting that other environmental cues might be more important drivers of this process

Effects of temperature and photoperiod on rainbow trout (Oncorhynchus mykiss) smoltification and haematopoiesis

First paragraph: Most freshwater fish would not be able to cope with the osmotic stress intrinsic to seawater, quickly dehydrating and dying, and so are bound to freshwater ecosystems (Quinn et al., 2016). However, anadromous salmonids have developed a strategy to minimize osmotic counter effects, thus allowing them to live in both freshwater, ideal for safe spawning, hatching and early growth stages, and seawater environments, rich in energy resources for fast growth (Hendry et al., 2004; Lima and Dill, 1990)