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Emerging clinical evidence implicates cellular senescence in the pathogenesis of various inflammatory conditions including inflammatory bowel diseases (IBDs), demonstrating that the intestinal stem cell crypts of patients with early Crohn’s disease exhibit markers positive for cell cycle inhibitor proteins. This phenomenon coupled with chronic systemic inflammation, a term coined “inflammaging," triggers many age-related pathologies and accelerates mortality. Our research evaluates the efficacy of interventions that target these death-resistant senescent cells to improve overall health and vitality. Particularly, we investigated the effects of Fisetin, a potent flavanoid with senolytic properties, in a dextran sodium sulfate (DSS) induced mouse model of colitis. Our findings reveal that Fisetin significantly inhibits senescence and inflammation in the colon while simultaneously enhancing the relative abundance of beneficial microbes, especially Akkermansia muciniphila, showcasing its potential for managing IBDs. Additionally, given the profound restoration of the microbiome and the central role of resident microbes in the production of metabolites essential for facilitating immunomodulation, we extended our investigations to further explore the effects of fecal microbiota transplant (FMT) from long-living Ames dwarf mice, characterized by low inflammatory status, into normal mice. Our results show notable shifts in microbial diversity, indicating that FMT may combat dysbiosis, a precursor to several conditions, including autoimmune, metabolic, and neurodegenerative diseases. Lastly, our exploration of potential anti-aging pharmacological interventions including Metformin (MF) and Trodusquemine (MSI-1436) during the postnatal window has demonstrated robust transcriptomic alterations of key biomarkers in the GH/Igf1 axis, such as Pi3k, Akt, and Mtor, suggesting delayed aging and improved liver function in young mice. These epigenetic changes underscore that early-life pharmacological interventions may forestall the onset of age-related metabolic disorders. All in all, there remains an urgent need for breakthroughs that can enhance healthspan to ensure that the rapidly growing population of older adults enjoys life in these extended years

In the post-industrial society, career management has become vitally important for assisting workers to be employable. This study aimed to investigate the relationship between career anchors and employability. The effort of researching these concepts is geared towards adding to the knowledge base in the field of Industrial and Organisational Psychology, so that the current organisation from which the sample was chosen and other organisations in South Africa can adopt a strong career management culture. A quantitative survey using primary data was conducted on a convenience sample (N=108) of full-time employees in a South African financial company. The Career Anchors Inventory (COI) and the Employability Attribute Scale (EAS) were used to gather data. The study found a statistically significant positive relationship between career anchors and employability. In addition, there were significant correlations between the sub-constructs of career anchors and employability, while significant differences in career anchor preferences and employability perceptions between males and females emerged. The only differences in career anchor preferences were detected between racial and age groups. The results indicate a mutual and positive relationship between career anchors and employability, which can be useful in career guidance in the 21st century. / Industrial & Organisational Psychology / M. A. (Industrial and Organisational Psychology)

Background Suicidal behavior is an important global health problem affecting also significant others. Both genetic and environmental influences play an important role in the development of suicidal behavior. There is a need of interventions for family and friends after a suicide attempt. The aim of this thesis was to assess the impact of family history of suicide (FHS) and early life adversity (ELA) on severity of suicidal behavior and on level of interpersonal problems in suicide attempters. Furthermore it aimed to evaluate a DBT-based skills training program, Family Connections (FC), for relatives and friends of suicide attempters. Methods Studies I and II included 181 suicide attempters. FHS was assessed with the Karolinska Self-Harm History Interview or in patient records. ELA was assessed with the Karolinska Interpersonal Violence Scale (KIVS) measuring exposure to interpersonal violence in childhood. Suicide intent was measured with the Freeman scale. Interpersonal problems were assessed with the Inventory of Interpersonal Problems (IIP). Study III, a pilot study evaluating the effect of FC for family members of suicide attempters, included 13 participants who completed the program with pre- and post-questionnaires. The experience of burden was assessed with the Burden Assessment Scale (BAS), general wellbeing with Brief Symptom Inventory (BSI) and level of depression was assessed with Beck Depression Inventory (BDI). The Swedish scale Questions About Family Members (QAFM) was used to explore the quality of the participants’ relationship with the patient and the Quality of Life Inventory (QOLI) was used to measure satisfaction with life situation. Study IV included 132 family members, and investigated the feasibility and preliminary efficacy of FC in psychiatric care. Participants were assessed pre- and post-intervention with the following self-report questionnaires: BAS, QAFM and Five Facet Mindfulness Questionnaire. Results Male suicide attempters with FHS made more serious and well planned suicide attempts and had higher suicide risk. FHS and exposure to interpersonal violence as a child were independent predictors of suicide in male suicide attempters. Regarding interpersonal problems, suicide attempters with FHS had significantly more often an intrusive personal style, indicating that they might have an impaired ability to create stable, long-lasting relationships. In the pilot study the participants reported a significant reduction in burden, an improved psychic health and an improvement in the relationship with the patient after completing FC. In the fourth study, FC showed to be feasible and effectively implemented in a psychiatric outpatient services clinic. Regarding burden, results were in line with the pilot study, with a significant reduction in all subscales in BAS. Conclusions High-risk patients call for a consideration of both ELA and FHS in clinical suicide risk assessment. In suicide attempters at biological risk, suicide might be prevented with the early recognition of environmental risks. Further, the interpersonal problems associated with FHS may cause difficulties for suicide attempters to accept or benefit from treatment, and caregivers should take into account the characteristics of the suicide attempter´s interpersonal functioning. The results from the pilot study provide support for the need and importance of an educational program addressed specifically to family members of suicide attempters. Preliminary results support the feasibility and potential value of an implementation of FC in psychiatric open care clinics.

Estudos recentes associaram fortemente a fisiopatologia da Depressão ao estresse crônico e suas conseqüências, desde o comportamento alterado até a disrupção do eixo HPA e mudanças na expressão gênica. A depressão é uma doença que afeta milhões de pessoas ao redor do mundo, causando um grande impacto na qualidade de vida dos pacientes. Evidências sugerem o papel contributivo do stress de início da vida (ELS) para Depressão Maior (MD). O paradigma do estresse crônico variável é amplamente utilizado, mas seus impactos não foram estudados no início da vida. Portanto, para entender melhor esta condição, os filhotes de ratos Wistar machos (P1-P21) foram expostos ao paradigma Multimodal ELS. Foram avaliados os níveis plasmáticos de corticosterona (cort) e os órgãos relacionados ao eixo HPA. Adicionalmente, estes foram avaliados durante a idade adulta no teste de consumo de sacarose (TCS), no teste de nado forçado (TNF) e no teste da caixa claro-escuro (TCE). Os resultados indicam que os filhotes não se habituaram ao ELS multimodal. Em P21, o peso das glândulas adrenais dos animais ELS é significantivamente maior, e o timo e o peso corporal diminuíram, quando comparados com o grupo controle. O timo também se mantém significativamente reduzido quando comparado ao grupo controle em P90. Além disso, os ratos adultos submetidos ao protocolo ELS apresentaram menor ingestão de sacarose e maior latência para o compartimento claro na TCE, quando comparados ao grupo controle. Um outro modelo animal que apresenta estresse intermitente e tem sido amplamente utilizado é o modelo da restrição do material de ninho. Neste modelo a redução do material do ninho promove uma disrupção no cuidado materno, e gera alterações no desenvolvimento encefálico e comportamental da prole. O ELS leva a um surgimento precoce da inibição do medo contextual e à maturação acelerada do hipocampo. Nós postulamos que a corticosterona desempenha um papel funcional na regulação do tempo de maturação das regiões subjacentes à aprendizagem e expressão de ameaças, incluindo o hipocampo e a amígdala. Nossa hipótese é que alterações nos níveis plasmáticos de corticosterona podem afetar o tempo de processos de maturação cerebral e comportamental. Portanto nosso objetivo foi avaliar como um bloqueador da síntese de corticosterona altera o comportamento de medo condicionado e expressão de BDNF em animais controle ou submetidos ao modelo ELS de redução de material do ninho. Tanto nos grupos controle como ELS utilizamos animais Naïve, ou que receberam Veículo ou Metirapona (MET; 50mg/kg) em P12. Em P18, P21 ou P28 grupos independentes de camundongos foram expostos a uma única sessão de condicionamento do medo, seguido 24 h depois por um único teste de contexto. A análise do comportamento de congelamento no teste de contexto revelou que o tratamento com MET bloqueou a aceleração na inibição do medo contextual em camundongos fêmeas submetidos ao ELS. Curiosamente, em filhotes machos controles tratados com MET, houve um atraso na curva de desenvolvimento de medo contextual. Observamos que houve um correlato do efeito do tratamento com Metirapona na expressão do BDNF em regiões límbicas (hipocampo ventral e amígdala basolateral). Com base nos presentes resultados, a CORT provavelmente desempenha um papel importante no momento do desenvolvimento típico e das mudanças associadas ao ELS no comportamento e na maturação do cérebro. A epilepsia é uma condição neurológica crônica caracterizada pela predisposição persistente a gerar crises epilépticas, e pelas consequências neurobiológicas, cognitivas, psicológicas e sociais desta condição. A depressão é uma comorbidade psiquiátrica muito comum em pacientes com epilepsia. Cada vez mais dados sugerem que a epilepsia, depressão e outros possíveis distúrbios psiquiátricos como a ansiedade compartilham mecanismos patogênicos. Nesse sentido, foram encontradas anormalidades na linhagem WAR (Wistar Audiogenic Rat) que a tornam um modelo interessante para o estudo do estresse, a Epilepsia e as comorbidades neuropsiquiátricas envolvidas. Com base nisso, o presente estudo teve comoxiv Godoy, L.D. objetivo avaliar na linhagem WAR: 1. Cuidados maternos na linhagem WAR nas condições controle e sob estresse 2. Comportamentos de tipo depressivo basal e após o kindling audiogênico (crises convulsivas crônicas- KAu). Não houve diferença no tempo em postura de amamentação ativa, licking/grooming ou tempo da mãe no ninho, e no número de ataques e comportamentos agressivos. Observamos um aumento na latência de ratas WAR para recuperar os filhotes após separação materna, e enquanto 100% das ratas Wistar agruparam toda a ninhada, nas fêmeas WAR foi observado apenas 40%. 2. Para avaliar os comportamentos de tipo depressivo, os ratos foram submetidos a 20 estímulos acústicos duas vezes ao dia (KAu) (Wistar-KAu, WAR-KAu), enquanto os respectivos grupos controle permaneceram sem estímulo (Wistar, WAR). Posteriormente, os grupos foram submetidos ao TCS e TNF Não houve diferença entre o grupo WAR e Wistar no TCS , porém o grupo WAR-KAu grupo apresentou um aumento significativo em relação aos grupos controles. No TNF ambos os grupos WAR e WAR-KAu apresentaram redução significativa de escalada na sessão teste quando comparados ao Wistar. Tomados em conjunto, esses achados indicam que o ELS pode gerar suceptibilidade às comorbidades psiquiátricas associadas ao estresse, e que os modelos experimentais em questão permitem investigar como os efeitos dos glicocorticoies se relacionam com o neurodesenvolvimento, especificamente na maturação do comportamento de medo e de estruturas límbicas. Além disso, dados preliminares indicam que, embora a linhagem WAR não apresente diferenças comportamentais maternas em condições basais, pode apresentar alterações sob o efeito de eventos estressantes. Também, com base nos achados, a susceptibilidade de crises convulsivas pode estar relacionada às alterações nas estratégias comportamentais em situações estressantes na vida adulta, que também pode constituir vulnerabilidade às comorbidades psiquiátricas. / Recent studies have strongly associated the pathophysiology of depression with chronic stress and its consequences, from altered behavior to HPA axis disruption and changes in gene expression. Depression is a disease that affects millions of people around the world, causing a major impact on the quality of life of patients. Evidence suggests the contributory role of early life stress (ELS) for Major Depression (MD). The variable chronic stress paradigm is widely used, but its impacts were not studied early in life. Therefore, to better understand this condition, male Wistar rat pups (P1-P21) were exposed to the Multimodal ELS paradigm. Plasma levels of corticosterone (CORT) and organs related to the HPA axis were evaluated. Additionally, these were evaluated during adulthood in the sucrose consumption test (SCT), the forced swimming test (FST) and the light-dark box test (LDT). The results indicate that pups did not habituate to multimodal ELS. In P21, the weight of the adrenal glands of the ELS animals is significantly greater, and the thymus and body weight decreased, when compared with the control group. The thymus also remains significantly reduced when compared to the control group in P90. In addition, adult rats submitted to the ELS protocol presented lower intake of sucrose and greater latency to light compartment in the LDT when compared to the control group. Another animal model that presents intermittent stress and has been widely used is the constraint model of nest material. In this model, the reduction of nest material promotes disruption in maternal care and causes changes in the encephalic and behavioral development of offspring. ELS leads to an early onset of contextual fear inhibition and accelerated maturation of the hippocampus. We postulate that CORT plays a functional role in regulating the maturation time of the regions underlying the learning and expression of threats, including the hippocampus and amygdala. Our hypothesis is that changes in plasma CORT levels may affect the timed brain and behavioral maturation processes. Therefore, our objective was to evaluate how a CORT synthesis blocker (Metyrapone; MET) alters conditioned fear behavior and BDNF expression in animals reared under control conditions or submitted to the ELS model of limited nesting bed. Both in control and ELS groups included Naïve animals or animals that received vehicle or MET; 50 mg/kg in P12. In P18, P21 or P28 independent groups of mice were exposed to a single session of fear conditioning, followed 24 hours later by a single context test. Analysis of the freezing behavior in the context test revealed that MET treatment blocked the acceleration of contextual fear suppression at P22 induced by ELS, with no difference between the P19 or P29 groups. This effect was observed mainly in female mice. Interestingly, in control male pups treated with MET, there was an altered contextual fear developmental curve. MET showed significant reduction in freezing in PND22, increase in freezing in PND29 followed by delayed suppression in P39. We observed that MET behavioural data were further supported by BDNF expression in limbic regions (ventral hippocampal and basolateral amygdala). Based on the current results, CORT probably plays an important role at the time of typical development and changes associated with ELS in the behavior and maturation of the brain. Epilepsy is a chronic neurological condition characterized by a persistent predisposition to epileptic seizures, and by neurobiological, cognitive, psychological and social consequences. Depression is a very common psychiatric comorbidity in patients with epilepsy. Increasingly data suggest that epilepsy, depression and other possible psychiatric disorders such as anxiety share pathogenic mechanisms. In this sense, abnormalities in the WAR strain (Wistar Audiogenic Rat) have been found that make it an interesting model for the study of stress, Epilepsy and neuropsychiatric comorbidities involved. Based on this, the present study aimed to evaluate in the WAR strain: 1. Maternal care under control and under stress conditions 2. Basal depressive type behaviors and after audiogenic kindling (chronic seizures-KAu).xvi Godoy, L.D. There was no difference for active breastfeeding posture, licking/grooming or time of mother in the nest and in the number of attacks and aggressive behaviors in maternal aggression test. WAR rats showed a higher latency to recover pup in pup retrieval test, whereas 100% of the Wistar rats grouped the entire litter, and in WAR it was only 40%. 2. In order to evaluate the depressive type behaviors, the rats were submitted to 20 acoustic stimuli twice a day (AuK) (Wistar-AuK, WAR-AuK), while the respective control groups remained without stimulus (Wistar, WAR). Subsequently, the groups were submitted to sucrose consumption test (SCT) and forced swim test (FST). There was no difference between the WAR and Wistar groups in the SCT, however the WAR-KAu group presented an increase in sucrose consumption in relation to the control groups 3 or 13 dasy after the AuK. In FST, both WAR and WARKAu groups showed a significant decrease in the test session when compared to Wistar. Taken together, these findings indicate that ELS may induce susceptibility to psychiatric comorbidities associated with stress, and that the current experimental models allow investigating how the effects of glucocorticoids are related to neurodevelopment, specifically in the maturation of fear behavior and limbic structures. In addition, preliminary data indicate that, although the WAR strain does not show maternal behavioral differences at baseline, it may present changes under stressful events. Also, based on the findings, the susceptibility of seizures may be related to changes in behavioral strategies in stressful situations in adult life, which may also constitute vulnerability to psychiatric comorbidities.

O desenvolvimento humano, presente desde a formação primária do indivíduo é constituído pelo conjunto das experiências vividas durante infância, incluindo as experiências de estresse precoce. Tais vivências repercutem nas ações do sujeito, podendo ser importante no aparecimento da depressão. Objetivos: explorar e analisar o significado do Estresse Precoce para portadores de depressão e construir um modelo teórico sobre o fenômeno estudado; caracterizar a amostra quanto às características sociodemográficas e de saúde; explorar e analisar, à luz do Interacionismo Simbólico, o significado do estresse precoce entre adultos portadores de depressão. Método: Estudo qualitativo que teve como referencial teórico norteador o Interacionismo Simbólico e como referencial metodológico a Teoria Fundamentada nos Dados. Os participantes desse estudo foram portadores de depressão que vivenciaram Estresse Precoce, recrutados no Centro de Atenção Psicossocial - CAPS III do interior paulista. Instrumentos utilizados: Childhood Trauma Questionnaire -CTQ, questionário sociodemográfico e entrevista em profundidade. O número de participantes foi se configurando conforme a análise da teoria emergente (amostragem teórica), totalizando 12 participantes. Resultados: a análise dos dados permitiu identificar o modelo teórico \"Caminhando entre a infância traumática e a vida adulta com depressão\". Sete categorias estruturaram a experiência relatada pelos participantes do estudo: \"Vivenciando o Estresse Precoce\"; \"Sentindo diferenciação de tratamento dentro no núcleo familiar\"; \"Percebendo a distribuição de papeis dentro do núcleo familiar\"; \"Construindo a si próprio\"; \"Aliando-se à passividade frente a incapacidade de decisões\"; \"Percebendo comportamentos nos pais e em si próprio\" e \"Vivenciando a depressão\". Conclusões: o estudo permitiu identificar um modelo teórico que simbolizou a forma como as vivências foram compreendidas pelos próprios sujeitos e como o significado de cada experiência foi se entrelaçando na composição do ser, moldando seu conjunto de símbolos, sendo expresso em sentimentos, percepções e comportamentos. O modelo teórico contribuiu para a compreensão dos significados construídos e as condições que afetam o indivíduo desde a infância traumática até a depressão na idade adulta / Human development, present since the primary formation of the individual, consists of all the lived experiences during childhood, including the early life stress experiences. Such experiences have repercussions on the subject actions, and may be important in the depression onset. Objectives: To explore and to analyze the meaning of early life stress in adulthood with depression and to construct a theoretical model about the phenomenon; To characterize the sample regarding sociodemographic and health characteristics; to explore and to analyze, in the according to Symbolic Interactionism, the meaning of early life stress among adults with depression. Method: Qualitative study that had as a guiding theoretical referential the Symbolic Interactionism and Grounded Theory as a methodological referential. The study participants were depressive individuals who experienced early life stress, recruited at the Center for Psychosocial Care - CAPS III in inner city of São Paulo, Brazil. Instruments: Childhood Trauma Questionnaire - CTQ, sociodemographic questionnaire and in-depth interview. The participants number was configured according to the analysis of the emerging theory (theoretical sampling), totaling 12 participants. Results: Data analysis allowed the identification of the theoretical model \"Walking between traumatic childhood and adulthood with depression\". Seven categories structures the experience: \"Experiencing early life stress\"; \"Feeling treatment differentiation within the family nucleus\"; \"Perceiving the distribution of characters within the family\"; \"Building Yourself\"; \"Allying to passivity in the face of inability to make decisions\"; \"Perceiving behaviors in parents and in yorurself\" and \"Experiencing depression\". Conclusions: the study allowed to identify a theoretical model that symbolized the way as the experiences were understood by the individuals and how the meaning of each experience was interlaced in the composition of being, shaping its set of symbols, being expressed in feelings, perceptions and behaviors. The theoretical model contributed to the understanding of the raised meanings and the conditions that affect the individual from traumatic childhood to depression in adulthood

In recent years, worldwide obesity rates have risen dramatically, putting major strain on public health systems and the economy. Obesity is a multifaceted disease and its development can be influenced by a variety of factors including genetic, psychological and environmental influences. One area of current focus in obesity research is that of early life programming. It has been well-established that certain early life factors can impact the physiology and behaviour of the offspring. Because of this, early life programming has become increasingly well studied in order to develop a deeper understanding of how early life can influence obesity development. Another area of interest lies in positive mood. While there has been much research into the effects of negative states such as stress and anxiety on feeding behaviour, there is still very little known about how positive states can influence food choice. Using rat models of prenatal stress, neonatal overnutrition and positive affect, this thesis aimed to investigate the effects of early life and mood factors on feeding behaviour and food choice. Prenatal stress has been extensively studied and is characterised by an enhanced stress response in the offspring. Using two rat models of prenatal stress- social and restraint stress, the effects of prenatal stress on feeding behaviour and food choice in the offspring were examined. In both models, no effects of prenatal stress on either food intake or food choice were observed. However, in both cases the expected alterations to the offspring's stress responses when exposed to an acute stressor were not replicated. This may suggest that models of prenatal stress are not as robust as often cited in the literature. As well as the prenatal environment, the early postnatal environment is also able to influence physiology and behaviour. In terms of obesity, a well-studied model is that of small litter size. Rats from small litters are over-nourished as neonates and because of this illustrate an increased body weight that persists throughout life. While this increase in weight gain has been well-established, there is no evidence examining the impact of neonatal overnutrition on long-term food choice. Therefore, food intake and food choice were measured in small and control litter rats over a 10-week period. When placed on an ad lib diet of bland chow, sucrose and lard, small litter rats consumed significantly more chow than control litter rats, whilst maintaining similar consumption of lard and sucrose. However, when offered a high-fat high-sugar (HFHS) pellet for two hours a day alongside ad lib chow, small litter rats illustrated increased consumption of the HFHS pellet compared to controls. This suggests that small litter rats may be programmed to adjust their food choices to enable them to maintain their increased body weight in comparison to controls. To examine the effects of positive affect on feeding behaviour, ultrasonic vocalisations (USVs, specifically those at 50 kHz) were used as a measure of positive affect in rats. In order to examine whether access to a food reward could induce a positive affect (as measured by an increase in 50 kHz USVs), rats were schedule-fed sweetened condensed milk and USVs measured before, during and after consumption. No differences in 50 kHz USVs were observed suggesting that a palatable food, whilst rewarding, does not alter affective state in the rat. Using heterospecific social contact (a tickling interaction simulating rough and tumble play) to induce positive affect, rats were presented with an hour-long sucrose preference test following social contact in order to examine the impact of positive affect on food choice. While no differences in sucrose consumption were found, a reduced sucrose preference was observed in rats receiving social contact compared to controls, suggesting that positive affect may play a role in mediating food choice. Finally, the effects of fasting (a negative stimulus thought to reduce 50 kHz USVs) and a food reward on motivation for social contact were examined. Both fasting and access to a food reward resulted in no differences in conditioned place preference to receive social interaction. Overall, the results obtained in this thesis implicate both neonatal overnutrition and, for the first time, positive affect as possible mediators of food choice, although further studies are required to fully establish these effects. Importantly, these results also raise questions regarding the reproducibility of some early life models, such as prenatal stress, and highlights the importance of sharing precise experimental protocols across laboratories. Through further investigation of the effects of early life and affective states on food consumption and choice, and the mechanisms behind these, this may enable the development of therapeutic interventions and preventative measures that can help slow, or even reverse, the global obesity epidemic.

Effective conservation strategies for imperiled species require an understanding of processes that influence fitness throughout the organism's life cycle and across the range of habitats needed to complete that cycle. I evaluated factors that affect population viability of bull trout Salvelinus confluentus, a threatened freshwater char species, throughout individual life stages and over the entire life cycle. I assessed the relationship between bull trout egg incubation success and environmental variables. Egg survival was negatively related to the percent of fine sediment in redds and positively related to hydraulic conductivity and the strength of downwelling. Next, I quantified juvenile bull trout survival rates and described movement patterns for this life stage. Juvenile bull trout emigrated from natal headwaters into larger rivers throughout the entire year and across a range of sizes. Estimates of juvenile survival rates improved dramatically when emigration was incorporated into the analysis. I integrated my observations of bull trout survival, growth, and movement to create a life-cycle model, which I used to better understand how populations respond to changes in specific demographic rates. Bull trout populations were particularly sensitive to changes in juvenile growth and survival. The relative effect of changes to fertility rates and adult survival varied depending upon whether a population was composed primarily of large, migratory, or smaller, resident individuals. Dispersal helped to lower the probability of extinction for small or declining populations when neighboring populations were stable. My research demonstrates that bull trout require access to habitats throughout entire watersheds to maintain population viability. My results suggest that limiting anthropogenic sources of fine sediment and maintaining areas of channel complexity that promote downwelling can be important for bull trout embryo survival. Management decisions should also consider the diverse behavior of juvenile bull trout and the wide range of habitat they use. Additionally, connectivity between populations is likely to be important for declining populations to persist. The diversity of life-history strategies expressed by bull trout helps maintain demographic stability within and among populations. As such, preservation of habitat integrity and full life-history diversity is imperative for conservation and recovery of bull trout populations range-wide.

Due to the significant threats posed by nonnative fish species worldwide, it is important to understand how life-history strategies of individual species interact with environmental conditions to explain the success or failure of nonnative fish invasions. Brown trout are prolific invaders, but often exhibit upstream distributional limits in Intermountain West streams, potentially due to a maladaptive reproductive life-history strategy influenced by hydrologic conditions in high-elevation areas. We used redd counts, egg survival experiments, and temperature modeling to investigate the reproductive life-history strategy of brown trout and its potential for success along an elevational stream gradient. We documented brown trout spawning in stream reaches at elevations higher than where we typically encounter brown trout during summer electrofishing surveys, indicating the potential for upstream invasion. We observed a decline in egg survival at higher elevation, cooler water sites, but did not document complete recruitment failure at these sites, again indicating the potential for successful invasion at this life-stage. Temperature data indicate that during most years, incubating brown trout eggs would likely fail to emerge from the gravel prior to peak spring flows in these high-elevation stream reaches, suggesting that damaging spring floods may cause significant egg and sac-fry mortality at high elevations, and may determine invasion success in these areas. Our results highlight the importance of identifying specific mechanisms of recruitment failure in order to better predict nonnative fish invasions in the future.

Lake Tahoe kokanee salmon have experienced decreasing mean adult size and fluctuating populations since 1970. We proposed to determine whether fish production was limited by spawning and incubation processes in Taylor Creek , or by growth constraints , or by mortality in the lake by studying egg-to-fry survival rates and early life history . Estimated egg-to-fry survival was 15. 9% for the 1994 brood year and 1.5% for the 1995 brood year. Egg-to-adult survival was 3.5% for the 1991 brood year and 5.9% for the 1992 brood year. Of the 35 possible survival scenarios, egg-to-fry survival was 7.5-20% and fry-to-adult survival (inlake phase) was 20-60%. The differing egg-to-fry survival rates corresponded to different stream temperature regimes during critical incubation periods. During and after the outmigration, fry inhabited the littoral zone, pelagic zone, and an estuarine environment created by a flooded meadow. Chironomids were the dominant prey in both 1995 and 1996 for fry in the littoral regions. Fry declined in the littoral zone approximately 30 days after peak outmigration during both 1995 and 1996. Juveniles and adults in the lake inhabited the upper 10 m of the water column and consumed primarily copepods for most of their limnetic life. Otolith analysis revealed that five year classes were present with the fifth year class representing 15.0% (1995) to 7.6% (1996) of the spawning population. Despite Lake Tahoe's low productivity, kokanee achieved greater size at age-4 than many other populations. Low densities (14.5 fish/hectare) and warmer winter temperatures may enable kokanee to reach greater size. Kokanee production may be limited by warm stream temperatures during spawning and early incubation in some years. Egg-to-fry survival is the most limiting factor. Enhancement of the kokanee population should focus on this phase of life history. Kokanee are not native to the Lake Tahoe Basin, which is considerably south of their historic range. Kokanee may be limited by inadequate adaptation to California's mild climate.