| 1. |
- Fraser, Thomas William Kenneth, et al.
(författare)
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Increased reactivity and monoamine dysregulation following stress in triploid Atlantic salmon (Salmo salar)
- 2015
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Ingår i: Comparative Biochemistry and Physiology A. - : Elsevier BV. - 1095-6433 .- 1531-4332. ; 185, s. 125-131
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Tidskriftsartikel (refereegranskat)abstract
- Artificial triploid salmonids are sterile and therefore commercially bred to prevent genetic interactions between wild and domestic fish strains. The full biological effects of having an extra chromosome set are largely unknown, but triploids are considered to be more sensitive to sub-optimal environmental conditions and to be stressed by the presence of diploid conspecifics. Brain serotonergic and dopaminergic activity are known to regulate the stress response in vertebrates, but monoamine systems in diploid and triploid fish have yet to be compared. Here we study monoamine neurochemistry in the telencephalon and brain stem of juvenile diploid and triploid Atlantic salmon (Salmo salar) in response to stress (unstressed vs stressed individuals) and holding (separate- vs mixed-ploidy) conditions. Both diploids and triploids showed an increase in serotonergic activity following stress, but the increase was significantly greater in the telencephalon of triploids compared to diploids. Furthermore, while telencephalic dopaminergic activity was significantly increased in diploids following stress, there was no response in triploids. Holding conditions had a significant effect on dopaminergic activity in the brain stem of diploids only, with lower values in mixed- compared to separate-ploidy conditions. These results suggest artificially produced triploids experience increased reactivity and monoaminergic dysregulation following stress that may impede their welfare and performance.
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| 2. |
- Abreu, Murilo S., et al.
(författare)
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Monoaminergic levels at the forebrain and diencephalon signal for the occurrence of mutualistic and conspecific engagement in client reef fish
- 2018
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Ingår i: Scientific Reports. - : NATURE PUBLISHING GROUP. - 2045-2322. ; 8
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Tidskriftsartikel (refereegranskat)abstract
- Social interactions are commonly found among fish as in mammals and birds. While most animals interact socially with conspecifics some however are also frequently and repeatedly observed to interact with other species (i.e. mutualistic interactions). This is the case of the (so-called) fish clients that seek to be cleaned by other fish (the cleaners). Clients face an interesting challenge: they raise enough motivation to suspend their daily activities as to selectively visit and engage in interactions with cleaners. Here we aimed, for the first time, to investigate the region-specific brain monoaminergic level differences arising from individual client fish when facing a cleaner (interspecific context) compared to those introduced to another conspecific (socio-conspecific context). We show that monoaminergic activity differences occurring at two main brain regions, the diencephalon and the forebrain, are associated with fish clients' social and mutualistic activities. Our results are the first demonstration that monoaminergic mechanisms underlie client fish mutualistic engagement with cleanerfish. These pathways should function as a pre-requisite for cleaning to occur, providing to clients the cognitive and physiological tools to seek to be cleaned.
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| 3. |
- Backstroem, Tobias, et al.
(författare)
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Social effects on AVT and CRF systems
- 2021
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Ingår i: Fish Physiology & Biochemistry. - : Springer Nature. - 0920-1742 .- 1573-5168. ; 47:6, s. 1699-1709
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Tidskriftsartikel (refereegranskat)abstract
- Stress and aggression have negative effects on fish welfare and productivity in aquaculture. Thus, research to understand aggression and stress in farmed fish is required. The neuropeptides arginine-vasotocin (AVT) and corticotropin-releasing factor (CRF) are involved in the control of stress and aggression. Therefore, we investigated the effect of agonistic interactions on the gene expression of AVT, CRF and their receptors in juvenile rainbow trout (Oncorhynchus mykiss). The social interactions lead to a clear dominant-subordinate relationship with dominant fish feeding more and being more aggressive. Subordinate fish had an upregulation of the AVT receptor (AVT-R), an upregulation of CRF mRNA levels, and higher plasma cortisol levels. The attenuating effect of AVT on aggression in rainbow trout is proposed to be mediated by AVT-R, and the attenuating effect of the CRF system is proposed to be mediated by CRF.
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| 4. |
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| 5. |
- Backström, Tobias, et al.
(författare)
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Stress effects on AVT and CRF systems in two strains of rainbow trout (Oncorhynchus mykiss) divergent in stress responsiveness
- 2011
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Ingår i: Hormones and Behavior. - : Elsevier BV. - 0018-506X .- 1095-6867. ; 59:1, s. 180-186
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Tidskriftsartikel (refereegranskat)abstract
- The aim for this study was to examine whether the F4 generation of two strains of rainbow trout divergent in their plasma cortisol response to confinement stress (HR: high responder or LR: low responder) would also differ in stress-induced effects on forebrain concentrations of mRNA for corticotropin-releasing factor (CRF). arginine vasotocin (AVT). CRF receptor type 1 (CRF-R1). CRF receptor type 2 (CRF-R2) and AVT receptor (AVT-R). In addition, plasma cortisol concentrations, brainstem levels of monoamines and monoamine metabolites, and behaviour during confinement were monitored. The results confirm that HR and LR trout differ in their cortisol response to confinement and show that fish of these strains also differ in their behavioural response to confinement. The HR trout displayed significantly higher locomotor activity while in confinement than LR trout. Moreover, following 180 min of confinement HR fish showed significantly higher forebrain concentrations of CRF mRNA than LR fish. Also, when subjected to 30 min of confinement HR fish showed significantly lower CRF-R2 mRNA concentrations than LR fish, whereas there were no differences in CRF-R1. AVT or AVT-R mRNA expression between LR and HR fish either at 30 or 180 min of confinement. Differences in the expression of CRF and CRF-R2 mRNA may be related to the divergence in stress coping displayed by these rainbow trout strains.
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| 6. |
- Behere, Anish, 1993-, et al.
(författare)
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Visualization of early oligomeric α‐synuclein pathology and its impact on the dopaminergic system in the (Thy‐1)‐h[A30P]α‐syn transgenic mouse model
- 2021
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Ingår i: Journal of Neuroscience Research. - : John Wiley & Sons. - 0360-4012 .- 1097-4547. ; 99:10, s. 2525-2539
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Tidskriftsartikel (refereegranskat)abstract
- Aggregation of alpha-synuclein (alpha-syn) into Lewy bodies and Lewy neurites is a pathological hallmark in the Parkinson ' s disease (PD) brain. The formation of alpha-syn oligomers is believed to be an early pathogenic event and the A30P mutation in the gene encoding alpha-syn, causing familial PD, has been shown to cause an accelerated oligomerization. Due to the problem of preserving antigen conformation on tissue surfaces, alpha-syn oligomers are difficult to detect ex vivo using conventional immunohistochemistry with oligomer-selective antibodies. Herein, we have instead employed the previously reported alpha-syn oligomer proximity ligation assay (ASO-PLA), along with a wide variety of biochemical assays, to discern the pathological progression of alpha-syn oligomers and their impact on the dopaminergic system in male and female (Thy-1)-h[A30P]alpha-syn transgenic (A30P-tg) mice. Our results reveal a previously undetected abundance of alpha-syn oligomers in midbrain of young mice, whereas phosphorylated (pS129) and proteinase k-resistant alpha-syn species were observed to a larger extent in aged mice. Although we did not detect loss of dopaminergic neurons in A30P-tg mice, a dysregulation in the monoaminergic system was recorded in older mice. Taken together, ASO-PLA should be a useful method for the detection of early changes in alpha-syn aggregation on brain tissue, from experimental mouse models in addition to post mortem PD cases.
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| 7. |
- Cocco, Arianna, et al.
(författare)
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Characterization of the gamma-aminobutyric acid signaling system in the zebrafish (danio rerio hamilton) central nervous system by reverse transcription-quantitative polymerase chain reaction
- 2017
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Ingår i: Neuroscience. - : Elsevier BV. - 0306-4522 .- 1873-7544. ; 343, s. 300-321
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Tidskriftsartikel (refereegranskat)abstract
- In the vertebrate brain, inhibition is largely mediated by raminobutyric acid (GABA). This neurotransmitter comprises a signaling machinery of GABA(A), GABA(B) receptors, transporters, glutamate decarboxylases (gads) and 4-aminobutyrate aminotransferase (abat), and associated proteins. Chloride is intimately related to GABAA receptor conductance, GABA uptake, and GADs activity. The response of target neurons to GABA stimuli is shaped by chloride-cation co-transporters (CCCs), which strictly control Cl- gradient across plasma membranes. This research profiled the expression of forty genes involved in GABA signaling in the zebrafish (Danio rerio) brain, grouped brain regions and retinas. Primer pairs were developed for reverse transcription-quantitative polymerase chain reaction (RT-qPCR). The mRNA levels of the zebrafish GABA system share similarities with that of mammals, and confirm previous studies in non-mammalian species. Proposed GABAA receptors are alpha(1)beta(2)gamma(2), alpha(1)beta(2)delta, alpha(2b)beta(3), alpha(2b)beta(3)delta, alpha(4)beta(2)gamma(2), alpha(4)beta(2)gamma, alpha(6b)beta(2)gamma(2) and alpha(6b)beta(2)delta. Regional brain differences were documented. Retinal hetero- or homomeric rho-composed GABAA receptors could exist, accompanying alpha(1)beta(y)gamma(2), alpha(1)beta(y)delta, alpha(6a)beta(y)gamma(2,) alpha(6a)beta(y)delta. Expression patterns of alpha(6a) and alpha(6b) were opposite, with the former being more abundant in retinas, the latter in brains. Given the stoichiometry alpha(6w)beta(y)gamma(z), alpha(6a-) or alpha(6b)-containing receptors likely have different regulatory mechanisms. Different gene isoforms could originate after the rounds of genome duplication during teleost evolution. This research depicts that one isoform is generally more abundantly expressed than the other. Such observations also apply to GABAB receptors, GABA transporters, GABA-related enzymes, CCCs and GABAA receptor associated proteins, whose presence further strengthens the proof of a GABA system in zebrafish.
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| 8. |
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| 9. |
- Cocco, Arianna, 1989-, et al.
(författare)
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Neural expression patterns and protein modeling of the GABAA receptor ζ subunit in the adult zebrafish (Danio rerio Hamilton, 1822)
- 2018
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Ingår i: Zebrafish. - 1545-8547 .- 1557-8542.
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Tidskriftsartikel (refereegranskat)abstract
- The zebrafish has a repertoire of twenty-six GABAA receptor subunits, including the paralogues π and ζ, homologous to the mammalian π. The brain mRNA levels of the π subunit are low, but the ζ gene is actively transcribed in D. rerio central nervous system and retinas. With a combined quantitative and qualitative gene expression profiling approach, this research characterized the distribution of the ζ transcript in the brain and eyes of the adult zebrafish. It was demonstrated that there are regional brain differences in the production of this transcript, with the stratum periventriculare of the tecta mesencephali having the highest mRNA levels for ζ. In the adult zebrafish retinas the bipolar cell layer presented staining for the ζ transcript. The three-dimensional structure of the ζ subunit of the GABAA receptor in zebrafish was also calculated in this study, with the human β3 as template. It presented four transmembrane α-helices and an amino-terminal β-loop framed into a disulfide bridge. It was therefore possible to place ζ in the superfamily of Cys-loop membrane proteins, to which GABAA receptor subunits belong. The current study presented a thorough characterization of a unique fish GABAA receptor subunit, which might have specific functions only typical of fish.
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| 10. |
- de Abreu, Murilo S., et al.
(författare)
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The variable monoaminergic outcomes of cleaner fish brains when facing different social and mutualistic contexts
- 2018
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Ingår i: PeerJ. - : PEERJ INC. - 2167-8359. ; 6
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Tidskriftsartikel (refereegranskat)abstract
- The monoamines serotonin and dopamine are important neuromodulators present in the central nervous system, known to be active regulators of social behaviour in fish as in other vertebrates. Our aim was to investigate the region-specific brain monoaminergic differences arising when individual cleaners face a client (mutualistic context) compared to when they are introduced to another conspecific (conspecific context), and to understand the relevance of visual assessment compared to the impact of physical contact with any partner. We demonstrated that serotoninergic activity at the diencephalon responds mostly to the absence of physical contact with clients whereas cerebellar dopaminergic activity responds to actual cleaning engagement. We provide first insights on the brain's monoaminergic (region-specific) response variations, involved in the expression of cleaner fishes' mutualistic and conspecific behaviour. These results contribute to a better understanding of the monoaminergic activity in accordance to different socio-behavioural contexts.
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