Behavioural fever and its underlying molecular mechanisms
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ABSTRACT: Fever implies a significant increase in corporal temperature that aids toward the resolution of infective processes such as viral disease. The majority of vertebrate species are not homeothermic therefore must rely upon the environment for temperature regulation. Here we show that in the zebrafish an artificial viral infection, induced by poly (I:C), induces a fever response regulated by the behavioral choice of temperature. We recorded 12 h of the diurnal cycle in zebrafish previously treated (first 12 hours dark cycle) with the pyrogen, poly (I:C) [10 μg⋅kg-1]. Fish, n=10, were held in a thermal gradient (36-180C) separated into 7 interconnected chambers. Presence or absence of individuals in each chamber was recorded each 15 minutes throughout the 12 hour period. After the experimental period we dissected whole brains for microarray analysis. In monitored zebrafish intraperitoneal treatment with poly (I:C) induced a febrile behaviour with significantly elevated temperature preference (T of about 32ºC) in stark contrast with the observed frequency for saline-injected fish (28ºC). Microarray analyses uncovered significant shifts in transcriptional activity that were highly directed in the poly (I:C)-treated fish housed in the thermal gradient. When compared to gene expression profiles from poly (I:C)-treated fish deprived of a thermal gradient we observed a less intense specific to the poly (I:C) challenge and interestingly observed a scattered generalised stress response. Our results highlight the influence of temperature preference in the development of the immune response in zebrafish.
Project description:Fever implies a significant increase in corporal temperature that aids toward the resolution of infective processes such as viral disease. The majority of vertebrate species are not homeothermic therefore must rely upon the environment for temperature regulation. Here we show that in the zebrafish an artificial viral infection, induced by poly (I:C), induces a fever response regulated by the behavioral choice of temperature. We recorded 12 h of the diurnal cycle in zebrafish previously treated (first 12 hours dark cycle) with the pyrogen, poly (I:C) [10 μg⋅kg-1]. Fish, n=10, were held in a thermal gradient (36-180C) separated into 7 interconnected chambers. Presence or absence of individuals in each chamber was recorded each 15 minutes throughout the 12 hour period. After the experimental period we dissected whole brains for microarray analysis. In monitored zebrafish intraperitoneal treatment with poly (I:C) induced a febrile behaviour with significantly elevated temperature preference (T of about 32ºC) in stark contrast with the observed frequency for saline-injected fish (28ºC). Microarray analyses uncovered significant shifts in transcriptional activity that were highly directed in the poly (I:C)-treated fish housed in the thermal gradient. When compared to gene expression profiles from poly (I:C)-treated fish deprived of a thermal gradient we observed a less intense specific to the poly (I:C) challenge and interestingly observed a scattered generalised stress response. Our results highlight the influence of temperature preference in the development of the immune response in zebrafish. Fever induced gene expression in zebrafish brain was measured at 24 after intra peritoneal injection with 1mg*Kg-1 of Poly (I:C) in zebrafish. Four independent experiments were performed to explore the transcriptomic profile induced by animals injected by Poly (I:C) with/whithout thermal gradient, saline solution (PBS), or control using different animals for each experiment.
Project description:The transcriptomic analysis was evaluated using RNA-seq of salmon challenged with the birnavirus IPNv under two different thermal conditions: (a) constant temperature (mean temperature 15 ± 0.9 ºC, “No-Fever”) and (b) temperature gradient (mean temperature 15 ± 7.4 ºC, “Fever”). In parallel, fish in another tank were treated by adding 100 ml virus free cell culture supernatant to the water (mean temperature 15 ± 7.4 ºC, "mock-infected"). We identified a specific transcriptomic signature for each group in the RNA-seq data and identifying a set of key components that control inflammatory modulation during behavioural fever upon viral infection in mobile ectotherms.
Project description:In this work, we describe the transcriptional profiles of adapted and non-adapted one-month-old Baikal whitefish juveniles after heat shock exposure. Preadapted fish were exposed to a repeated thermal rise of 6 °C above control temperature every 3 days throughout embryonic development. One month after hatching, preadapted and non-adapted larvae were either maintained at control temperatures (12 °C) or exposed to an acute thermal stress (TS) of 12 °C above control temperature. The information on transcriptional profiles will contribute to further understanding of the mechanisms of adaptation of whitefish to the environment.
Project description:We sequenced mRNA from 4 liver samples of the large yellow croaker (Larimichthys crocea) taken from thermal stress treatment fish, normal temperature treatment fish, cold stress treatment fish and fasting stress treatment fish, respectively, to investigate the transcriptome and comparative expression profiles of the large yellow croaker liver undergoing thermal stress, cold stress and fasting.
Project description:Changes in environmental temperature can profoundly change species habitats and result in populations facing suboptimal environments. Many aquatic organisms are restricted in terms of migration by their habitat requirements. Also due to anthropogenic migration barriers (both physical as well as chemical), organisms are often left with no choice but to acclimate (or, in the long run, adapt) to their changing environment. The scope of this study is to investigate thermal acclimation in zebrafish by combining data from several levels of biological organization. Zebrafish were acclimated to a higher temperature (8°C increase compared to controls) or a lower temperature (8°C decrease compared to controls) in an acute as well as a prolonged and a chronic scenario (4, 14 and 28 days). General condition of the fish was assessed by determining organismal (condition factor) and biochemical (energy homeostasis) parameters. Data at the transcriptome level (using printed oligonucleotide microarrays containing 15,208 probes and real time PCR) were applied to clarify the mechanisms underlying the thermal acclimation response in zebrafish.
Project description:Female fish are known to be sensitive to temperature during reproduction, but the long-term consequences on offspring adaptive behaviour and their underlying intergenerational mechanisms remain unknown. We studied the intergenerational consequences of female rainbow trout (Oncorhynchus mykiss) exposure to high (17°C) or normal temperature (12°C) on offspring behavioural phenotypes. We also analysed genome-wide gene expression in eggs and embryos to elucidate the mechanisms by which thermal maternal exposure impacts offspring behaviour. Here we show that a thermal maternal stress induces emotional and cognitive disorders in offspring. Fear responses to a novel environment were inhibited in 17°C offspring indicating global emotional blunting. Thermal stress in mothers also decreased spatial learning abilities in progeny. Behavioural phenotypes were associated with the dysregulation of several genes known to play major roles in neurodevelopment. This is especially true for auts2, a key gene for neurodevelopment in fish and mammals, more specifically neuronal migration and neurite extension, and critical for the acquisition of neurocognitive function in fish and mammals. In addition to auts2, our analysis revealed the dysregulation of another neurodevelopment gene (dpysl5) as well as genes associated with human cognitive disorders (arv1, plp2). Our study also revealed major differences in maternal mRNA abundance in the eggs following maternal exposure to high temperature indicating that some of the observed intergenerational effects are mediated by maternally-inherited mRNAs accumulated in the egg. Together, our observations shed new light on the intergenerational determinism of fish behaviour and associated underlying mechanisms. They also stress the importance of maternal history on fish adaptive capacities in a context of global climate changes.
Project description:We sequenced mRNA from 4 liver samples of the large yellow croaker (Larimichthys crocea) taken from thermal stress treatment fish, normal temperature treatment fish, cold stress treatment fish and fasting stress treatment fish, respectively, to investigate the transcriptome and comparative expression profiles of the large yellow croaker liver undergoing thermal stress, cold stress and fasting. Liver mRNA profiles of control group (LB2A), thermal stress group (LC2A), cold stress group (LA2A) and 21-day fasting group (LF1A) were generated by RNA-seq, using Illumina HiSeq 2000.
Project description:Normal human monocyte derived dentritic cells were subjected to fever-like thermal conditions (39M-0C) or to normal temperature (37M-0C) ) for 180 minutes, and global genome-wide gene expression profile was mesured using the human HG U133 plus array (Affymetrix).
Project description:Changes in environmental temperature can profoundly change species habitats and result in populations facing suboptimal environments. Many aquatic organisms are restricted in terms of migration by their habitat requirements. Also due to anthropogenic migration barriers (both physical as well as chemical), organisms are often left with no choice but to acclimate (or, in the long run, adapt) to their changing environment. The scope of this study is to investigate thermal acclimation in zebrafish by combining data from several levels of biological organization. Zebrafish were acclimated to a higher temperature (8°C increase compared to controls) or a lower temperature (8°C decrease compared to controls) in an acute as well as a prolonged and a chronic scenario (4, 14 and 28 days). General condition of the fish was assessed by determining organismal (condition factor) and biochemical (energy homeostasis) parameters. Data at the transcriptome level (using printed oligonucleotide microarrays containing 15,208 probes and real time PCR) were applied to clarify the mechanisms underlying the thermal acclimation response in zebrafish. All three biological replicates of liver samples from acute (4 days) and chronic (28 days) controls (26°), warm acclimation (34°) and cold acclimation (18°) were analyzed using microarrays. An A-optimal interwoven loop design was used in which each sample appeared on an array twice in Cy3 and twice in Cy5, resulting in 36 arrays for 18 samples.
Project description:Zebrafish eggs were collected at 28 °C, and split into three embryonic incubation temperature groups (24 °C, 28 °C, 32 °C). When larvae reaching first feeding, the incubation temperature of larvae from 24 °C and 32 °C was gradually changed to 28 °C, and all fish were kept at 28 °C for later development until adulthood. At 100 d post-fertilization, 7 replicates from each temperature group were intraperitoneally (i.p.) injected with 2 μl of 50 mg/ml lipopolysaccharide (LPS) from Pseudomonas aeruginosa 10, while another 7 replicates were i.p. injected with 2 μl phosphate-buffered saline as control. At 12 h post-injection, the spleen was dissected, and total RNA was extracted. Five LPS-treated replicates and five controls were used for building RNA libraries and sequencing. The differential gene expression analysis were performed between fish from different embryonic incubation temperatures (24 °C vs 28 °C; 32 °C vs 28 °C), and between LPS treatment and control within each temperature group (24 °C LPS vs control; 28 °C LPS vs control; 32 °C LPS vs control). Totally, 251 differentially expressed genes (DEGs, 71 up-/180 down-regulated) were identified in fish from 24 °C embryonic incubation temperature compared to fish kept at constant 28 °C (DESeq2, adjusted p-value < 0.05, |fold change| > 1.5); and 660 DEGs (385 up-/275 down-regulated) were identified in fish from 32 °C embryonic incubation temperature compared to fish kept at 28 °C. By comparing LPS-treated fish to control, 567 DEGs (271 up-/296 down-regulated) were identified in fish from embryonic incubation temperature of 24 °C, 140 DEGs (80 up-/60 down-regulated) were identified in fish kept at constant 28 °C; and 49 DEGs (11 up-/38 down-regulated) were identified in fish from the 32 °C embryonic incubation temperature group.