| 1. |
- Brijs, Jeroen, et al.
(författare)
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Cardiorespiratory upregulation during seawater acclimation in rainbow trout: effects on gastrointestinal perfusion and postprandial responses
- 2016
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Ingår i: American Journal of Physiology-Regulatory Integrative and Comparative Physiology. - : American Physiological Society. - 0363-6119 .- 1522-1490. ; 310:9
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Tidskriftsartikel (refereegranskat)abstract
- Increased gastrointestinal blood flow is essential for euryhaline fishes to maintain osmotic homeostasis during the initial phase of a transition from freshwater to seawater. However, the cardiorespiratory responses and hemodynamic changes required for a successful long-term transition to seawater remain largely unknown. In the present study, we simultaneously measured oxygen consumption rate ((M)over dot(O2)), cardiac output (CO), heart rate (HR), and gastrointestinal blood flow (GBF) in rainbow trout (Oncorhynchus mykiss) acclimated to either freshwater or seawater for at least 6 wk. Seawater-acclimated trout displayed significantly elevated ((M)over dot(O2)) (day: 18%, night: 19%), CO (day: 22%, night: 48%), and GBF (day: 96%, night: 147%), demonstrating that an overall cardiorespiratory upregulation occurs during seawater acclimation. The elevated GBF was achieved via a combination of increased CO, mediated through elevated stroke volume (SV), and a redistribution of blood flow to the gastrointestinal tract. Interestingly, virtually all of the increase in CO of seawater-acclimated trout was directed to the gastrointestinal tract. Although unfed seawater-acclimated trout displayed substantially elevated cardiorespiratory activity, the ingestion of a meal resulted in a similar specific dynamic action (SDA) and postprandial GBF response as in freshwater-acclimated fish. This indicates that the capacity for the transportation of absorbed nutrients, gastrointestinal tissue oxygen delivery, and acid-base regulation is maintained during digestion in seawater. The novel findings presented in this study clearly demonstrate that euryhaline fish upregulate cardiovascular function when in seawater, while retaining sufficient capacity for the metabolic and cardiovascular changes associated with the postprandial response.
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| 2. |
- Brijs, Jeroen, et al.
(författare)
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Exposure to seawater increases intestinal motility in euryhaline rainbow trout (Oncorhynchus mykiss).
- 2017
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Ingår i: The Journal of experimental biology. - : The Company of Biologists. - 1477-9145 .- 0022-0949. ; 220, s. 2397-2408
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Tidskriftsartikel (refereegranskat)abstract
- Upon exposure to seawater, euryhaline teleosts need to imbibe and desalinate seawater to allow for intestinal ion and water absorption, as this is essential for maintaining osmotic homeostasis. Despite the potential benefits of increased mixing and transport of imbibed water for increasing the efficiency of absorptive processes, the effect of water salinity on intestinal motility in teleosts remains unexplored. By qualitatively and quantitatively describing in vivo intestinal motility of euryhaline rainbow trout (Oncorhynchus mykiss), this study demonstrates that in freshwater, the most common motility pattern consisted of clusters of rhythmic, posteriorly propagating contractions that lasted ∼1-2 minutes followed by a period of quiescence lasting ∼4-5 minutes. This pattern closely resembles mammalian migrating motor complexes (MMCs). Following a transition to seawater, imbibed seawater resulted in a significant distension of the intestine and the frequency of MMCs increased two to three-fold with a concomitant reduction in the periods of quiescence. The increased frequency of MMCs was also accompanied by ripple-type contractions occuring every 12 to 60 seconds. These findings demonstrate that intestinal contractile activity of euryhaline teleosts is dramatically increased upon exposure to seawater, which is likely part of the overall response for maintaining osmotic homeostasis as increased drinking and mechanical perturbation of fluids is necessary to optimize intestinal ion and water absorption. Finally, the temporal response of intestinal motility in rainbow trout transitioning from freshwater to seawater coincides with previously documented physiological modifications associated with osmoregulation and may provide further insight on the underlying reasons shaping the migration patterns of salmonids.
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| 3. |
- Brijs, Jeroen, et al.
(författare)
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Increased gastrointestinal blood flow: An essential circulatory modification for euryhaline rainbow trout (Oncorhynchus mykiss) migrating to sea
- 2015
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 5
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Tidskriftsartikel (refereegranskat)abstract
- The large-scale migrations of anadromous fish species from freshwater to seawater have long been considered particularly enigmatic, as this life history necessitates potentially energetically costly changes in behaviour and physiology. A significant knowledge gap concerns the integral role of cardiovascular responses, which directly link many of the well-documented adaptations (i.e. through oxygen delivery, water and ion transport) allowing fish to maintain osmotic homeostasis in the sea. Using long-term recordings of cardiorespiratory variables and a novel method for examining drinking dynamics, we show that euryhaline rainbow trout (Oncorhynchus mykiss) initiate drinking long before the surrounding environment reaches full seawater salinity (30–33ppt), suggesting the presence of an external osmo-sensing mechanism. Onset of drinking was followed by a delayed, yet substantial increase in gastrointestinal blood flow through increased pulse volume exclusively, as heart rate remained unchanged. While seawater entry did not affect whole animal energy expenditure, enhanced gastrointestinal perfusion represents a mechanism crucial for ion and water absorption, as well as possibly increasing local gastrointestinal oxygen supply. Collectively, these modifications are essential for anadromous fish to maintain homeostasis at sea, whilst conserving cardiac and metabolic scope for activities directly contributing to fitness and reproductive success.
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| 4. |
- Brijs, Jeroen, et al.
(författare)
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Increased mitochondrial coupling and anaerobic capacity minimizes aerobic costs of trout in the sea
- 2017
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 7
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Tidskriftsartikel (refereegranskat)abstract
- Anadromy is a distinctive life-history strategy in fishes that has evolved independently many times. In an evolutionary context, the benefits of anadromy for a species or population must outweigh the costs and risks associated with the habitat switch. The migration of fish across the freshwater-ocean boundary coincides with potentially energetically costly osmoregulatory modifications occurring at numerous levels of biological organization. By integrating whole animal and sub-cellular metabolic measurements, this study presents significant findings demonstrating how an anadromous salmonid (i.e. rainbow trout, Oncorhynchus mykiss) is able to transform from a hyper- to hypo-osmoregulatory state without incurring significant increases in whole animal oxygen consumption rate. Instead, underlying metabolic mechanisms that fuel the osmoregulatory machinery at the organ level (i.e. intestine) are modulated, as mitochondrial coupling and anaerobic metabolism are increased to satisfy the elevated energetic demands. This may have positive implications for the relative fitness of the migrating individual, as aerobic capacity may be maintained for locomotion (i.e. foraging and predator avoidance) and growth. Furthermore, the ability to modulate mitochondrial metabolism in order to maintain osmotic balance suggests that mitochondria of anadromous fish may have been a key target for natural selection, driving species adaptations to different aquatic environments.
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| 5. |
- Brijs, Jeroen, et al.
(författare)
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The presence and role of interstitial cells of Cajal in the proximal intestine of shorthorn sculpin (Myoxocephalus scorpius)
- 2017
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Ingår i: Journal of Experimental Biology. - : The Company of Biologists. - 0022-0949 .- 1477-9145. ; 220, s. 347-357
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Tidskriftsartikel (refereegranskat)abstract
- Rhythmic contractions of the mammalian gastrointestinal tract can occur in the absence of neuronal or hormonal stimulation due to the generation of spontaneous electrical activity by interstitial cells of Cajal (ICC) that are electrically coupled to smooth muscle cells. The myogenically-driven component of gastrointestinal motility patterns in fish likely also involves ICC, however, little is known of their presence, distribution and function in any fish species. In the present study, we combined immunohistochemistry and in vivo recordings of intestinal motility to investigate the involvement of ICC in the motility of the proximal intestine in adult shorthorn sculpin (Myoxocephalus scorpius). Antibodies against anoctamin 1 (Ano1, a Ca2+-activated Cl- channel), revealed a dense network of multipolar, repeatedly branching cells in the myenteric region of the proximal intestine, similar in many regards to the mammalian ICC-MY network. The addition of benzbromarone, a potent blocker of Ano1, altered the motility patterns seen in vivo after neural blockade with TTX. The results indicate that ICC are integral for the generation and propagation of the majority of rhythmic contractile patterns in fish, although their frequency and amplitude can be modulated via neural activity.
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| 6. |
- Chen, Bao Nan, et al.
(författare)
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Sensory innervation of the guinea pig colon and rectum compared using retrograde tracing and immunohistochemistry.
- 2016
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Ingår i: Neurogastroenterology and motility : the official journal of the European Gastrointestinal Motility Society. - : Wiley. - 1365-2982. ; 28:9, s. 1306-1316
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Tidskriftsartikel (refereegranskat)abstract
- Neurons in lumbar and sacral dorsal root ganglia (DRG) comprise extrinsic sensory pathways to the distal colon and rectum, but their relative contributions are unclear. In this study, sensory innervation of the rectum and distal colon in the guinea pig was directly compared using retrograde labeling combined with immunohistochemistry.
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| 7. |
- Gouveneaux, A., et al.
(författare)
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Morphology and fluorescence of the parapodial light glands in Tomopteris helgolandica and allies (Phyllodocida: Tomopteridae)
- 2017
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Ingår i: Zoologischer Anzeiger. - : Elsevier BV. - 0044-5231. ; 268, s. 112-125
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Tidskriftsartikel (refereegranskat)abstract
- The histology of putative light organs in the parapodia of five species of Tomopteris (pelagic annelids) is examined and compared using light, epifluorescence and scanning electron microscopy. The structural homology of rosette glands in the parapodial pinnae of the tail-bearing species T. helgolandica and T. pacifica, and hyaline glands of the tail-less species T. carpenteri, T. planktonis and T. septentrionalis is highlighted. However, the rosette glands point towards the ramus of the coelomic cavity inside the parapodia, whereas the hyaline glands point towards the surrounding water and penetrate the pinnal surface on the posterior side of the parapodia. Further, in order to assess the photogenic properties of rosette glands from T. helgolandica, we analysed the distribution and the temporal dynamics of their endogenous fluorescence in isolated parapodia in response to light emission induced by I
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| 8. |
- Olsson, Catharina, 1968
(författare)
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Tyrosine hydroxylase immunoreactivity is common in the enteric nervous system in teleosts
- 2016
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Ingår i: Cell and Tissue Research. - : Springer Science and Business Media LLC. - 0302-766X .- 1432-0878. ; 364:2, s. 231-243
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Tidskriftsartikel (refereegranskat)abstract
- Tyrosine hydroxylase (TH) is the rate-limiting enzyme in the synthesis of catecholamines and TH immunoreactivity is indicative of cells synthesising either adrenaline/noradrenaline or dopamine. In this study, the distribution of TH immunoreactivity was examined in two distantly related teleost species, zebrafish (Danio rerio) and shorthorn sculpin (Myoxocephalus scorpius). In both species, TH-immunoreactive nerve cell bodies and varicose nerve fibres were common in the myenteric plexus of the intestine. However, no TH-immunoreactive nerve cell bodies were seen in the sculpin stomach. The TH-immunoreactive nerve cell bodies seemed to constitute a larger proportion of the total enteric population in shorthorn sculpin (50±5 %, n=3067 cells) compared with zebrafish (14±2 %, n=10,163 cells). In contrast, in sculpin, the TH-immunoreactive cells were smaller than the average enteric nerve cell bodies, whereas in zebrafish, the relationship was the opposite. In developing zebrafish larvae, TH-immunoreactive nerve cell bodies were common (approx. 75 % of the total population) at 3 days post-fertilization (dpf), but decreased in numbers between 3 and 7 dpf. In conclusion, in contrast to previous studies, TH-immunoreactive intrinsic neurons are common in the fish gut. Their role and function need to be further characterized in order to understand the potential importance of this enteric subpopulation in controlling various gut functions.
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