The expression of nuclear and membrane estrogen receptors in the European eel throughout spermatogenesis

[EN] Estradiol (E-2) can bind to nuclear estrogen receptors (ESR) or membrane estrogen receptors (GPER). While mammals possess two nuclear ESRs and one membrane GPER, the European eel, like most other teleosts, has three nuclear ESRs and two membrane GPERs, as the result of a teleost specific genome duplication. In the current study, the expression of the three nuclear ESRs (ESR1, ESR2a and ESR2b) and the two membrane GPERs (GPERa and GPERb) in the brain-pituitary-gonad (BPG) axis of the European eel was measured, throughout spermatogenesis. The eels were first transferred from freshwater (FW) to seawater (SW), inducing parallel increases in E2 plasma levels and the expression of ESRs. This indicates that salinity has a stimulatory effect on the E-2 signalling pathway along the BPG axis. Stimulation of sexual maturation by weekly injections of human chorionic gonadotropin (hCG) induced a progressive decrease in E-2 plasma levels, and different patterns of expression of ESRs and GPERs in the BPG axis. The expression of nuclear ESRs increased in some parts of the brain, suggesting a possible upregulation due to a local production of E-2. In the testis, the highest expression levels of the nuclear ESRs were observed at the beginning of spermatogenesis, possibly mediating the role of E2 as spermatogonia renewal factor, followed by a sharply decrease in the expression of ESRs. Conversely, there was a marked increase observed in the expression of both membrane GPERs throughout spermatogenesis, suggesting they play a major role in the final stages of spermatogenesis.Funded by the Spanish Ministry of Science and Innovation (REPRO-TEMP project; AGL2013-41646-R) and IMPRESS (Marie Sklodowska-Curie Actions; Grant agreement no: 642893). M.C. Vilchez has a predoctoral grant from UPV PAID Programme (2011-S2-02-6521), M. Morini has a predoctoral grant from Generalitat Valenciana (Programa Grisolia). D.S. Penaranda was supported by MICINN and UPV (PTA2011-4948-1).Morini, M.; Peñaranda, D.; Vilchez Olivencia, MC.; Tveiten, H.; Lafont, A.; Dufour, S.; Pérez Igualada, LM.... (2017). The expression of nuclear and membrane estrogen receptors in the European eel throughout spermatogenesis. Comparative Biochemistry and Physiology Part A Molecular & Integrative Physiology. 203:91-99. doi:10.1016/j.cbpa.2016.08.020S919920

The impact of fishing-induced mortality on the evolution of alternative life-history tactics in brook charr

Although contemporary trends indicative of evolutionary change have been detected in the life-history traits of exploited populations, it is not known to what extent fishing influences the evolution of alternative life-history tactics in migratory species such as salmonids. Here, we build a model to predict the evolution of anadromy and residency in an exploited population of brook charr, Salvelinus fontinalis. Our model allows for both phenotypic plasticity and genetic change in the age and size at migration by including migration reaction norms. Using this model, we predict that fishing of anadromous individuals over the course of 100 years causes evolution in the migration reaction norm, resulting in a decrease in average probabilities of migration with increasing harvest rate. Moreover, we show that differences in natural mortalities in freshwater greatly influence the magnitude and rate of evolutionary change. The fishing-induced changes in migration predicted by our model alter population abundances and reproductive output and should be accounted for in the sustainable management of salmonids

Thermal imprinting modifies bone homeostasis in cold-challenged sea bream (Sparus aurata)

Fish are ectotherms and temperature plays a determinant role in their physiology, biology and ecology, and is a driver of seasonal responses. The present study assessed how thermal imprinting during embryonic and larval stages modified the response of adult fish to low water temperature. We targeted the gilthead sea bream, which develops a condition known as winter syndrome when it is exposed to low water temperatures. Eggs and larvae of sea bream were exposed to four different thermal regimes and then the response of the resulting adults to a low temperature challenge was assessed. Sea bream exposed to a high-low thermal regime as eggs and larvae (HLT; 22 degrees C until hatch and then 18 degrees C until larvae-juvenile transition) had increased plasma cortisol and lower sodium and potassium in response to a cold challenge compared with the other thermal history groups. Plasma glucose and osmolality were increased in cold-challenged HLT fish relative to the unchallenged HLT fish. Cold challenge modified bone homeostasis/responsiveness in the low-high thermal regime group (LHT) relative to other groups, and ocn, ogn1/2, igf1, gr and tr alpha/beta transcripts were all downregulated. In the low temperature group (LT) and HLT group challenged with a low temperature, alkaline phosphatase (ALP) and tartrate-resistant acid phosphatase (TRAP) activities were decreased relative to unchallenged groups, and bone calcium content also decreased in the LT group. Overall, the results indicate that thermal imprinting during early development of sea bream causes a change in the physiological response of adults to a cold challenge.Seventh Framework Programme project Lifecycle [EU-FP7 222719

A Synthesis of Tagging Studies Examining the Behaviour and Survival of Anadromous Salmonids in Marine Environments

This paper synthesizes tagging studies to highlight the current state of knowledge concerning the behaviour and survival of anadromous salmonids in the marine environment. Scientific literature was reviewed to quantify the number and type of studies that have investigated behaviour and survival of anadromous forms of Pacific salmon (Oncorhynchus spp.), Atlantic salmon (Salmo salar), brown trout (Salmo trutta), steelhead (Oncorhynchus mykiss), and cutthroat trout (Oncorhynchus clarkii). We examined three categories of tags including electronic (e.g. acoustic, radio, archival), passive (e.g. external marks, Carlin, coded wire, passive integrated transponder [PIT]), and biological (e.g. otolith, genetic, scale, parasites). Based on 207 papers, survival rates and behaviour in marine environments were found to be extremely variable spatially and temporally, with some of the most influential factors being temperature, population, physiological state, and fish size. Salmonids at all life stages were consistently found to swim at an average speed of approximately one body length per second, which likely corresponds with the speed at which transport costs are minimal. We found that there is relatively little research conducted on open-ocean migrating salmonids, and some species (e.g. masu [O. masou] and amago [O. rhodurus]) are underrepresented in the literature. The most common forms of tagging used across life stages were various forms of external tags, coded wire tags, and acoustic tags, however, the majority of studies did not measure tagging/handling effects on the fish, tag loss/failure, or tag detection probabilities when estimating survival. Through the interdisciplinary application of existing and novel technologies, future research examining the behaviour and survival of anadromous salmonids could incorporate important drivers such as oceanography, tagging/handling effects, predation, and physiology

Så skal mangfoldet blomstre og fargelegge bildet av det norske "vi": Å tenke mangfold om igjen

Mangfold er et tema som er i tiden, også politisk sett. Etter terrorangrepet i Oslo og på Utøya 22. juli 2011 har det vært fokus på det mangfoldige Norge. Det er i fra statsministerens tale i Jamaat-moskeen jeg har hentet tittelen på oppgaven. I denne talen ble det pratet om hvor viktig det er at vi nå står sammen, uavhengig av religion, etnisitet, kjønn og rang. Så skal mangfoldet blomstre og fargelegge bildet av det norske "vi" (Stoltenberg, 2011) Det kritiske temaet i denne oppgaven er, med dette i tankene, mangfold i barnehage. Skal mangfold blomstre, ser jeg på barnehagen som en av flere viktige arenaer for å starte dette arbeidet. Denne oppgaven tar utgangspunkt i poststrukturelle teorier for å kritisere ideen om stabile kategorier og identiteter. Med en poststrukturalistisk tilnærming tillates det at man ser temaet ut i fra forskjellige perspektiver, og at ingen av disse eier sannheten. I et poststrukturelt perspektiv anses vår kunnskap som en sosial konstruksjon og det finnes ikke bare én sannhet. Boken Beretninger fra en muslimsk barnehage i Norge (Rhedding-Jones, Nordli, & Tanveer, 2011) er valgt som datamateriale for denne oppgaven. Boken gir en innblikk i hverdagen i en muslimsk barnehage, og har en rekke korte historier som jeg er utgangspunkt for analysene mine. Forskningsspørsmålene for oppgaven er; Hvordan kommer motstand mot dominerende diskurser til uttrykk i tekstene? Analysestrategien jeg har benyttet i denne oppgaven er kritisk lesning inspirert av genealogiske analyser ala Cannella (1997) og Lyngstad (2006), diskursteori og dekonstruksjon. Jeg har i oppgaven benyttet genealogiske analyser som inspirasjon til å se på maktproduksjon i tekstene, gjennom å se på normalitet. Diskursteori har inspirert meg til å se på begreper som vedrører identiteter; posisjonering og representasjon. Til slutt har jeg benyttet meg av inspirasjon fra dekonstruksjon til å søke å åpne opp for å se praksiser, ord og begreper på nye måter

The effect of temperature and pH on the growth and physiological response of juvenile yellowtail kingfish Seriola lalandi in recirculating aquaculture systems

A search for a viable new fish species for culture in recirculating aquaculture systems (RAS) in the Netherlands identified yellowtail kingfish Seriola lalandi as having excellent potential. To assist in determining the most appropriate water quality conditions for this species in RAS, the effect of water temperature (21, 23.5, 25, 26.5 and 29°C) and pH (6.58, 7.16 and 7.85) was tested in two separate experiments. Growth performance, feed conversion, stress-physiological and metabolic parameters were assessed in juvenile yellowtail kingfish grown in pilot-scale RAS. Growth was optimised at a water temperature of 26.5°C, in combination with maximum food intake and optimum food conversion ratio (FCR). Increasing temperature from 21°C to 26.5°C resulted in a 54% increase in the fish's final weight after 30. days. A water pH of 6.58 resulted in mortality and inhibited both growth and FCR due to physiological disruptions to which the fish could not adapt