<p><i>Saprolegnia parasitica</i> and <i>Aphanomyces astaci </i>are parasitic water moulds belonging to the Oomycetes. Despite their importance as parasites they are very little studied at the molecular level and the work described in this thesis was aimed at increasing the molecular knowledge of these organisms by cloning and characterising genes of potential importance for reproduction and pathogenicity.</p><p>Stage-specific transcripts from<i> Saprolegnia parasitica</i> were isolated by differential display RT-PCR. One of the markers, <i>puf1 </i>encodes a putative mRNA binding protein which may be involved in post-transcriptional regulation of gene expression. <i>S. parasitica puf1 </i>is expressed exclusively in spore cysts that have not been determined for germination or repeated zoospore emergence indicating that the cyst stage has two phases, of about equal duration, which are physiologically and transcriptionally distinct. A similar expression pattern is observed in <i>Aphanomyces </i>spp. with different regulation of spore development and in the transcript is detected in both primary and secondary cysts.</p><p>A putative chitinase <i>AaChi1</i>, was cloned from the crayfish plague fungus, <i>Aphanomyces astaci. </i>Analysis of chitinase activity and <i>AaChi1</i> expression showed that chitinase in <i>A. astaci </i>is constitutively expressed in growing and sporulating mycelia, but absent in zoospores, a pattern which reflects the infectious life cycle of <i>A. astaci</i>. This expression pattern is conserved between the four known genotypes of <i>A. astaci</i>, in contrast to saprophytic and fish-pathogenic <i>Aphanomyces </i>spp. </p><p>Genetic and physiological analysis were conducted on five strains of <i>Aphanomyces, </i>isolated from suspected outbreaks of crayfish plague in Spain and Italy. The strains are not virulent against freshwater crayfish, and RAPD PCR and ITS sequence analysis show that they are unrelated to the crayfish plague fungus, <i>A. astaci.</i></p>

Saprolegnia parasitica and Aphanomyces astaci are parasitic water moulds belonging to the Oomycetes. Despite their importance as parasites they are very little studied at the molecular level and the work described in this thesis was aimed at increasing the molecular knowledge of these organisms by cloning and characterising genes of potential importance for reproduction and pathogenicity. Stage-specific transcripts from Saprolegnia parasitica were isolated by differential display RT-PCR. One of the markers, puf1 encodes a putative mRNA binding protein which may be involved in post-transcriptional regulation of gene expression. S. parasitica puf1 is expressed exclusively in spore cysts that have not been determined for germination or repeated zoospore emergence indicating that the cyst stage has two phases, of about equal duration, which are physiologically and transcriptionally distinct. A similar expression pattern is observed in Aphanomyces spp. with different regulation of spore development and in the transcript is detected in both primary and secondary cysts. A putative chitinase AaChi1, was cloned from the crayfish plague fungus, Aphanomyces astaci. Analysis of chitinase activity and AaChi1 expression showed that chitinase in A. astaci is constitutively expressed in growing and sporulating mycelia, but absent in zoospores, a pattern which reflects the infectious life cycle of A. astaci. This expression pattern is conserved between the four known genotypes of A. astaci, in contrast to saprophytic and fish-pathogenic Aphanomyces spp. Genetic and physiological analysis were conducted on five strains of Aphanomyces, isolated from suspected outbreaks of crayfish plague in Spain and Italy. The strains are not virulent against freshwater crayfish, and RAPD PCR and ITS sequence analysis show that they are unrelated to the crayfish plague fungus, A. astaci.

The neuropeptides arginine-vasotocin (AVT) and corticotropin-releasing hormone (CRH) are involved in the hypothalamic-pituitary-interrenal (HPI) axis. During stress, the HPI axis is activated and cortisol is released into the blood. In addition to their role in the HPI axis, AVT and CRH also have behavioural effects. The roles of AVT and CRH in stress responses and agonistic behaviour were studied in this thesis, using two different models. In the first model, two strains of rainbow trout (Onchorhynchus mykiss) divergent in stress-induced release of cortisol were investigated. This was done by observing behaviour and stress responses under different conditions. These strains were found to have divergent stress coping strategies based on the observed behaviour and levels of plasma cortisol. This divergence in behaviour could be associated with the CRH system, since the mRNA levels of CRH differed between the strains during stress. However, no differences between strains were observed in AVT or its receptor expressions. In the second model, non-selected rainbow trout were paired and the effect of intracerebroventricular (icv) injections of an active substance (AVT, CRH or the CRH related peptide Urotensin-I (UI)) on fights for dominance was investigated. One fish of the pair received the active substance icv and the other received saline icv. Fish receiving AVT became subordinate in accordance with the suggestion that AVT attenuates aggression in territorial vertebrates. Fish receiving CRH became subordinate whereas UI showed no effect on fights for dominance. Further, both CRH and UI induced an anxiety-related behaviour similar to non-ambulatory motor activity in rats. In addition, CRH appeared to affect the dopaminergic and serotonergic systems. In this thesis, it is suggested that CRH is involved in the behavioural modulation of the stress coping strategies in teleost fish. Further, AVT and CRH seem to act inhibitory on aggressive behaviour.

The first objective of this thesis was to investigate effects of endocrine disruptors on the developing brain and gonads of bird embryos. The substances studied were the insecticide methoxychlor, and nine UV-filters (3-benzylidene camphor (3BC), 4 methyl benzylidene camphor (4MBC), benzophenone (BP) 1,2 and 3, 4 hydroxy benzophenone (4 HB), 4 dihydroxy benzophenone (4DHB), benzyl salicylate (BS), and ethyl-4-aminobenzoate Et-PABA)), commonly used in cosmetic products. Some of these substances have no estrogenic effect in vitro, but have been shown to be estrogenic in vivo. The PCB-mixture Clophen A50 is a well-known inducer of biotransformation enzymes and was co-administered with methoxychlor and the UV-filters 3BC and 4MBC. Exposure to 3BC or 4MBC caused ovotestis formation and malformations of the Müllerian ducts in Japanese quail embryos. Co-exposure to one of these compounds and Clophen A50 enhanced the effects, indicating that Clophen A50 potentiates the effects of the UV-filters. Embryonic co-exposure to Clophen A50 and methoxychlor caused a disturbed male sexual behaviour. The metabolites of methoxychlor are estrogen receptor (ER)α-selective, which indicates that the effects on behaviour following embryonic treatment were mediated by ERα. Another objective in this thesis was to localize estrogen receptors (ERs) in the brain of adult and embryonic Japanese quail. The ER localization provides a basis for mechanistic studies on effects of endocrine disruptors, by the identification of estrogen-responsive areas in the brain. We found that ERβ, not previously implicated in sex-differentiation of the brain, was the only ER-subtype present in a sexually dimorphic brain area during differentiation. In conclusion, the estrogenic effects of 3BC, 4MBC and methoxychlor were increased by co-exposure to PCB. These results raise concern since many wildlife species, as well as humans, carry large body burdens of persistent organic pollutants like PCBs, which potentially can interact and enhance the effects of other endocrine disruptors.

<p>In all vertebrate species, reproduction is a hormonally controlled process, important for growth and maturation of gonads and germ cells. Production of functional germ cells is of outmost importance to secure the survival of a species. Fish comprises 50% of the known vertebrates and are found in aquatic habitats all over the world. Even though fish have evolved a wide variety of morphological and physiological characteristics, due to large differences in the living environment, the growth an maturation of germ cells follows the same pattern in all species. In this thesis the focus has been directed on oocyte growth and development in Arctic char (Salvelinus alpinus), and if stress might inflict disturbances on the reproductive systems.</p><p>All sexually mature female egg laying vertebrates produces yolky eggs surrounded by an eggshell. Production of yolk and egg shell is under estrogenic control and it is known that production of egg components can be induced in male and juvenile fish by estrogenic substances. Many manmade chemicals have been found to interfere with hormonally controlled processes. Therefore production of the egg yolk precursor, vitellogenin (VTG), and the egg shell components, vitelline envelope proteins (VEP), have been used as biomarkers for estrogenic effect. Exposure to endocrine disrupting substances (EDS) does not only give rise to hormonal effects on the organism, but in addition it also gives rise to an increase in stress hormone, cortisol (F), levels. </p><p>It is evident that a wide variety of substances may affect Arctic char oocyte growth and maturation. VTG and VEP production is found to be under dose dependent estrogenic control, but the production was directly affected by F. Under natural condition it has been found that F increases towards ovulation. Even though both VTG and VTG is under estrogenic control, these studies showed that stress lead to a decrease of VTG while the VEP production increased. These effects was only observed on protein levels indicating that a post transcriptional down regulation of VTG production is mediated by F in Arctic char.</p><p>In order for an egg to become fertilizatible, it must undergo a maturation phase. This maturation phase is primarily induced by gonadotropins, which in turn induce the production of species specific maturation inducing substances (MIS). To investigate oocyte development in Arctic char a characterization of its MIS receptor was made. The MIS receptor is localized on the oocyte surface and displays a single class of high affinity and low capacity binding sites. The binding moieties displays association and dissociation kinetics typical of steroid membrane receptors.</p><p>Even though high specificity for Arctic char MIS was observed, it was found that some EDS bind to the Arctic char oocyte membrane receptor. This suggest that certain EDS might affect oocyte maturation and thereby might alter the reproductive success. Furthermore, it was found that F did not bind to the MIS receptor in Arctic char. It is therefore suggested that oocytes are more sensitive to stress during the growth phase than during maturation</p>

<p>The crayfish plague refractory crayfish, <i>Pacifastacus leniusculus</i>, which can harbour the fungal parasite within melanotic sheath, are found to constitutively express the gene encoding for prophenoloxidase (proPO) after mimicking parasite attack. In contrast, the susceptible crayfish, <i>Astacus astacus</i>, responds to the parasite by increased levels of proPO transcript, particularly in the semigranular haemocytes. The upregulation of proPO could confer a temporary resistance towards the fungal infection, suggesting that additional factors are involved in maintaining the balance between host and parasite. The resistant crayfish may have adapted to the parasite by increasing the transcript level of immune genes. The parasite can be considered as a symbiont since it does not harm the host rather than it activates the immune gene and possibly preventing other pathogens to become established.</p><p>Two serine proteinase genes encoding a subtilisin-like (<i>AaSP1</i>) and a trypsin (<i>AaSP2</i>) enzyme were isolated from the crayfish plague fungus, <i>Aphanomyces astaci</i>. These proteinases are prepropeptides and generate mature proteins of 39 kDa and 29 kDa, respectively. Characterisation of <i>AaSP1</i> suggests that the enzyme may be involved in intracellular control mechanisms rather than playing a role in pathogenesis. The <i>AaSP2 </i>transcript was not controlled by catabolic repression, but was induced by crayfish plasma, implying a role in pathogenesis toward the crayfish host. </p><p>Physiology and genetics of five <i>Aphanomyces</i> strains, which were isolated from moribund crayfish, were characterised with regard to their pathogen diversity. These strains are not virulent against crayfish. Some physiological properties of these strains differed from <i>A. astaci</i>, such as growth rate, germination and production of chitinase. Genetic analysis clearly indicated that they are not related to <i>A. astaci</i> and their name are proposed to be <i>Aphanomyces repetans</i>.</p><p>The crayfish <i>P. leniusculus </i>was found to be susceptible to white spot syndrome virus infection. The virus has a significant effect to the population of crayfish haemocyte. The number and proportion of granular cell from virus-infected crayfish were higher than in controls, indicating granular cells are more resistant to and may interact by some means with the virus.</p><p>Two morphotypes of the crayfish parasite <i>Psorospermium haeckeli</i> obtained from different crayfish hosts of different geographical origin were analysed for ribosomal ITS DNA in order to compare their genetic diversity. The sequence difference between them was found largely in ITS 1 and ITS 2 regions, which was variable in length and showed 66% and 58% sequence similarity. Thus, different morphotypes of <i>P. haeckeli</i> are genetically diverse.</p>

The crayfish plague refractory crayfish, Pacifastacus leniusculus, which can harbour the fungal parasite within melanotic sheath, are found to constitutively express the gene encoding for prophenoloxidase (proPO) after mimicking parasite attack. In contrast, the susceptible crayfish, Astacus astacus, responds to the parasite by increased levels of proPO transcript, particularly in the semigranular haemocytes. The upregulation of proPO could confer a temporary resistance towards the fungal infection, suggesting that additional factors are involved in maintaining the balance between host and parasite. The resistant crayfish may have adapted to the parasite by increasing the transcript level of immune genes. The parasite can be considered as a symbiont since it does not harm the host rather than it activates the immune gene and possibly preventing other pathogens to become established. Two serine proteinase genes encoding a subtilisin-like (AaSP1) and a trypsin (AaSP2) enzyme were isolated from the crayfish plague fungus, Aphanomyces astaci. These proteinases are prepropeptides and generate mature proteins of 39 kDa and 29 kDa, respectively. Characterisation of AaSP1 suggests that the enzyme may be involved in intracellular control mechanisms rather than playing a role in pathogenesis. The AaSP2 transcript was not controlled by catabolic repression, but was induced by crayfish plasma, implying a role in pathogenesis toward the crayfish host. Physiology and genetics of five Aphanomyces strains, which were isolated from moribund crayfish, were characterised with regard to their pathogen diversity. These strains are not virulent against crayfish. Some physiological properties of these strains differed from A. astaci, such as growth rate, germination and production of chitinase. Genetic analysis clearly indicated that they are not related to A. astaci and their name are proposed to be Aphanomyces repetans. The crayfish P. leniusculus was found to be susceptible to white spot syndrome virus infection. The virus has a significant effect to the population of crayfish haemocyte. The number and proportion of granular cell from virus-infected crayfish were higher than in controls, indicating granular cells are more resistant to and may interact by some means with the virus. Two morphotypes of the crayfish parasite Psorospermium haeckeli obtained from different crayfish hosts of different geographical origin were analysed for ribosomal ITS DNA in order to compare their genetic diversity. The sequence difference between them was found largely in ITS 1 and ITS 2 regions, which was variable in length and showed 66% and 58% sequence similarity. Thus, different morphotypes of P. haeckeli are genetically diverse.

In all vertebrate species, reproduction is a hormonally controlled process, important for growth and maturation of gonads and germ cells. Production of functional germ cells is of outmost importance to secure the survival of a species. Fish comprises 50% of the known vertebrates and are found in aquatic habitats all over the world. Even though fish have evolved a wide variety of morphological and physiological characteristics, due to large differences in the living environment, the growth an maturation of germ cells follows the same pattern in all species. In this thesis the focus has been directed on oocyte growth and development in Arctic char (Salvelinus alpinus), and if stress might inflict disturbances on the reproductive systems. All sexually mature female egg laying vertebrates produces yolky eggs surrounded by an eggshell. Production of yolk and egg shell is under estrogenic control and it is known that production of egg components can be induced in male and juvenile fish by estrogenic substances. Many manmade chemicals have been found to interfere with hormonally controlled processes. Therefore production of the egg yolk precursor, vitellogenin (VTG), and the egg shell components, vitelline envelope proteins (VEP), have been used as biomarkers for estrogenic effect. Exposure to endocrine disrupting substances (EDS) does not only give rise to hormonal effects on the organism, but in addition it also gives rise to an increase in stress hormone, cortisol (F), levels. It is evident that a wide variety of substances may affect Arctic char oocyte growth and maturation. VTG and VEP production is found to be under dose dependent estrogenic control, but the production was directly affected by F. Under natural condition it has been found that F increases towards ovulation. Even though both VTG and VTG is under estrogenic control, these studies showed that stress lead to a decrease of VTG while the VEP production increased. These effects was only observed on protein levels indicating that a post transcriptional down regulation of VTG production is mediated by F in Arctic char. In order for an egg to become fertilizatible, it must undergo a maturation phase. This maturation phase is primarily induced by gonadotropins, which in turn induce the production of species specific maturation inducing substances (MIS). To investigate oocyte development in Arctic char a characterization of its MIS receptor was made. The MIS receptor is localized on the oocyte surface and displays a single class of high affinity and low capacity binding sites. The binding moieties displays association and dissociation kinetics typical of steroid membrane receptors. Even though high specificity for Arctic char MIS was observed, it was found that some EDS bind to the Arctic char oocyte membrane receptor. This suggest that certain EDS might affect oocyte maturation and thereby might alter the reproductive success. Furthermore, it was found that F did not bind to the MIS receptor in Arctic char. It is therefore suggested that oocytes are more sensitive to stress during the growth phase than during maturation

Made available in DSpace on 2016-08-17T17:11:04Z (GMT). No. of bitstreams: 1 DISSERTACAO_GABRIEL CARDOSO NEVES.pdf: 3003386 bytes, checksum: a66fc84507d8a67ed01e8957922250cd (MD5) Previous issue date: 2015-05-05 / FUNDAÇÃO DE AMPARO À PESQUISA E AO DESENVOLVIMENTO CIENTIFICO E TECNOLÓGICO DO MARANHÃO / The objectives of this study were to determine the effect of different levels of nitrite (NO2 -) associated with calcium (Ca2+) in the water on the performance, biochemical and hematological parameters of jundiá (Rhamdia quelen). One hundred and sixty animals were stored in 16 boxes (n = 10) of 40 liters with constant aeration and kept in a water recirculation system with UV filter for 60 days. The design was completely randomized with 4 treatments and 4 replications in a factorial design with two levels of NO2 - (0,05 e 1,4 mg L-1) x 2 levels of Ca2+ in water (5 e 20 mg L-1). Fish (8.9±0.2 g and 15.0±0.8 cm) were fed with the diet (32% CP and max. 2.0% Ca2+) twice a day at home. Was done daily removal of waste by siphoning, and 80% of the water was replaced by another with nitrite and calcium levels previously set. The nitrite and calcium levels were maintained by the addition of sodium nitrite (NaNO2) and calcium carbonate (CaCO3), respectively. They evaluated: the growth performance, biochemical and hematological parameters for juvenile catfish (Rhamdia quelen). The final survival was not affected by nitrite levels associated with Ca2+. At 30 days, it was observed that there was no change (P>0.05) in weight gain, biomass, specific growth rate and feed conversion between the analyzed treatments. At 60 days, there was an increase (P<0.05) in weight gain, biomass and specific growth rate for animals of the control treatment in relation to the treatment high NO2 - and Ca2+ down, and for treatment low NO2 - and Ca2+ high in relation to the treatment high NO2 - and Ca2+ high. At the end of the experiment, it was found that the feed intake was higher of the treatment low NO2 - and Ca2+ high in relation to the treatment high NO2 - and Ca2+ high. No change (P>0.05) for converting food to end the 60-day trial. No change (P>0.05) in the levels of lactate and glycogen in the liver. The treatment showed control levels (P<0.05) higher protein in the liver compared to fish subjected to high Ca2+ and NO2 - low. Glucose levels in fish liver were higher (P<0.05) in the control treatment in relation to the treatments low NO2 - and Ca2+ high and high NO2 - and Ca2+ down. The levels of lactate and glycogen in muscle showed a lower (P<0.05) in the control treatment in relation to the treatment high NO2 - and Ca2+ down. The protein level in the muscle was lower (P<0.05) in treatment high NO2 - and Ca2+ high in relation to treatment low NO2 - and Ca2+ high and treatment high NO2 - and Ca2+ down. Glucose levels in the muscle had a higher (P<0.05) of the control treatment in relation to the treatment high NO2- and Ca2+ low, and higher of the treatment low NO2- and Ca2+ high in relation to the treatment high NO2- and Ca2+ high. The increase in hardness does not favored animals subjected to high levels of nitrite in relation to the hemoglobin levels. Fish exposed to high NO2 - and Ca2+ high, showed a reduction in this parameter for the processing low NO2 - and Ca2+ high (T2). This result may be an indication that there was blood hemoglobin oxidation in methemoglobin, causing poisoning in fish. Thus, the use of 20 mg L- 1Ca2+ in water has no positive effect in reducing the toxicity of nitrite in relation to performance, biochemical and hematological parameters for juvenile catfishes (Rhamdia quelen). / Os objetivos neste trabalho foram determinar o efeito de diferentes níveis de nitrito (NO2 -) associado ao cálcio (Ca2+) na água sobre o desempenho, parâmetros bioquímicos e hematológicos em juvenis de jundiá (Rhamdia quelen). Cento e sessenta animais foram estocados em 16 caixas (n=10) de 40 litros com aeração constante e mantidos em um sistema de recirculação de água com filtro U.V durante 60 dias. O delineamento utilizado foi o inteiramente casualizado com 4 tratamentos e 4 repetições em esquema fatorial com 2 níveis de NO2 - (0,05 e 1,4 mg L-1) x 2 níveis de Ca2+ na água (5 e 20 mg L-1). Os peixes (8,9±0,2 g e 15,0±0,8 cm) foram alimentados com ração extrusada (32% PB e máx. 2,0 % de Ca2+) duas vezes ao dia à vontade. Diariamente foi feito a retirada dos resíduos por sifonagem, e 80% da água foi substituída por outra com níveis de nitrito e cálcio previamente ajustados. Os níveis de nitrito e cálcio foram mantidos por meio da adição de nitrito de sódio (NaNO2) e carbonato de cálcio (CaCO3), respectivamente. Foram avaliados: o desempenho zootécnico, os parâmetros bioquímicos e hematológicos para juvenis de jundiá (Rhamdia quelen). A sobrevivencia final não foi afetada pelos niveis de nitrito associado ao Ca2+. Aos 30 dias, observou-se que não houve alterações (P>0,05) no ganho de peso, biomassa, taxa de crescimento específico e conversão alimentar entre os tratamentos analisados. Aos 60 dias, observou-se aumento (P<0,05) no ganho de peso, biomassa e taxa de cresimento específico para os animais do tratamento controle em relação ao tratamento alto NO2 - e Ca2+ baixo, e para o tratamento baixo NO2 - e Ca2+ alto em relação ao tratamento alto NO2 - e Ca2+ alto. Ao final do período experimental, observou-se que o consumo de ração foi maior no tratamento baixo NO2 - e Ca2+ alto em relação ao tratamento alto NO2 - e Ca2+ alto. Não houve alterações (P>0,05) para a converção alimentar ao final dos 60 dias experimentais. Não houve alterações (P>0,05) nos níveis de lactato e glicogênio no fígado. Os animais do tratamento controle apresentaram níveis (P<0,05) mais elevados de proteína no fígado em relação aos peixes submetidos a alto NO2 - e Ca2+ baixo. Os níveis de glicose no fígado dos peixes foram maiores (P<0,05) no tratamento controle em relação aos tratamentos baixo NO2 - e Ca2+ alto e alto NO2 - e Ca2+ baixo. Os níveis de lactato e glicogênio no músculo apresentaram-se menor (P<0,05) no tratamento controle em relação ao tratamento alto NO2 - e Ca2+ baixo. O nível de proteína no músculo foi menor (P<0,05) no tratamento alto NO2 - e Ca2+ alto em relação ao tratamento baixo NO2 - e Ca2+ alto e ao tratamento alto NO2 - e Ca2+ baixo. Os níveis de glicose no músculo apresentaram-se maior (P<0,05) no tratamento controle em relação ao tratamento alto NO2 - e Ca2+ baixo, e maior (P<0,05) no tratamento baixo NO2 - e Ca2+ alto em relação ao tratamento alto NO2 - e Ca2+ alto. O aumento da dureza não favoreceu os animais submetidos a elevados níveis de nitrito em relação ao niveis de hemoglobina. Os peixes expostos a alto NO2 - e Ca2+ alto, apresentaram uma redução neste parâmetro em relação ao tratamento baixo NO2 - e Ca2+ alto (T2). Tal resultado pode ser um indicativo de que houve oxidação da hemoglobina do sangue em metahemoglobina, causando intoxicação nos peixes. Sendo assim, a utilização de 20 mg L- 1Ca2+ na água não apresenta efeito positivo na redução da toxidez do nitrito em relação ao desempenho, parâmetros bioquímicos e hematológicos para juvenis de jundiá (Rhamdia quelen).

Two distinct stress coping strategies, proactive and reactive, have been stated in various animal studies, each associated with a set of behavioural and physiological characteristics. In a given challenging situation, proactive animals show more aggression, a higher general activity and a predominant sympathetic reaction. In contrast, the reactive copers respond more with immobility and avoidance, and a predominant parasympathetic/hypothalamic activation. This divergence in coping has also been indicated in salmonid fish. Interestingly, many of the differences reported between sea-ranched and wild fish resembles characteristics that differentiate proactive and reactive copers. In the present thesis it is shown that individuals with divergent stress coping styles are identifiable in several brown trout (Salmo trutta) populations. Further, the results show that the distribution of individuals displaying these distinct stress coping strategies differs between populations. This strongly indicates that these traits are heritable and that the variation in selection regime in the native rivers influences these traits. In addition, the results show that populations with hatchery origin are biased towards having higher frequencies of trout displaying a proactive style than populations having wild origin. Also, even though the frequency of early sexual maturation, known as a viable alternative life history in salmonids, differs between populations of brown trout, no link between stress coping strategy and early sexual maturation were found. However, this thesis show that maternal contribution, in the form of egg size, is of major importance whether the progeny will sexually mature early and that it also might be of importance for stress coping strategy. Further, correlations of traits commonly associated with stress coping strategies and behavioural syndromes across context and over time is investigated. The results show that individuals with a strong sympathetic reactivity are more prone to change their behaviour than others.