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- Ahi, Ehsan Pashay, et al.
(författare)
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Appetite regulating genes in zebrafish gut; a gene expression study
- 2022
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Ingår i: PLOS ONE. - : PUBLIC LIBRARY SCIENCE. - 1932-6203. ; 17:7
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Tidskriftsartikel (refereegranskat)abstract
- The underlying molecular pathophysiology of feeding disorders, particularly in peripheral organs, is still largely unknown. A range of molecular factors encoded by appetite-regulating genes are already described to control feeding behaviour in the brain. However, the important role of the gastrointestinal tract in the regulation of appetite and feeding in connection to the brain has gained more attention in the recent years. An example of such inter-organ connection can be the signals mediated by leptin, a key regulator of body weight, food intake and metabolism, with conserved anorexigenic effects in vertebrates. Leptin signals functions through its receptor (lepr) in multiple organs, including the brain and the gastrointestinal tract. So far, the regulatory connections between leptin signal and other appetite-regulating genes remain unclear, particularly in the gastrointestinal system. In this study, we used a zebrafish mutant with impaired function of leptin receptor to explore gut expression patterns of appetite-regulating genes, under different feeding conditions (normal feeding, 7-day fasting, 2 and 6-hours refeeding). We provide evidence that most appetite-regulating genes are expressed in the zebrafish gut. On one hand, we did not observed significant differences in the expression of orexigenic genes (except for hcrt) after changes in the feeding condition. On the other hand, we found 8 anorexigenic genes in wild-types (cart2, cart3, dbi, oxt, nmu, nucb2a, pacap and pomc), as well as 4 genes in lepr mutants (cart3, kiss1, kiss1r and nucb2a), to be differentially expressed in the zebrafish gut after changes in feeding conditions. Most of these genes also showed significant differences in their expression between wild-type and lepr mutant. Finally, we observed that impaired leptin signalling influences potential regulatory connections between anorexigenic genes in zebrafish gut. Altogether, these transcriptional changes propose a potential role of leptin signal in the regulation of feeding through changes in expression of certain anorexigenic genes in the gastrointestinal tract of zebrafish.
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| 2. |
- Ahi, Ehsan Pashay, et al.
(författare)
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Transcriptional study of appetite regulating genes in the brain of zebrafish (Danio rerio) with impaired leptin signalling
- 2019
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Ingår i: Scientific Reports. - : NATURE PUBLISHING GROUP. - 2045-2322. ; 9
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Tidskriftsartikel (refereegranskat)abstract
- The hormone leptin is a key regulator of body weight, food intake and metabolism. In mammals, leptin acts as an anorexigen and inhibits food intake centrally by affecting the appetite centres in the hypothalamus. In teleost fish, the regulatory connections between leptin and other appetite-regulating genes are largely unknown. In the present study, we used a zebrafish mutant with a loss of function leptin receptor to investigate brain expression patterns of 12 orexigenic and 24 anorexigenic genes under different feeding conditions (normal feeding, 7-day fasting, 2 and 6-hours refeeding). Expression patterns were compared to wild-type zebrafish, in order to identify leptin-dependent differentially expressed genes under different feeding conditions. We provide evidence that the transcription of certain orexigenic and anorexigenic genes is influenced by leptin signalling in the zebrafish brain. We found that the expression of orexigenic genes was not affected by impaired leptin signalling under normal feeding conditions; however, several orexigenic genes showed increased transcription during fasting and refeeding, including agrp, apln, galr1a and cnr1. This suggests an inhibitory effect of leptin signal on the transcription of these orexigenic genes during short-term fasting and refeeding in functional zebrafish. Most pronounced effects were observed in the group of anorexigenic genes, where the impairment of leptin signalling resulted in reduced gene expression in several genes, including cart family, crhb, gnrh2, mc4r, pomc and spx, in the control group. This suggests a stimulatory effect of leptin signal on the transcription of these anorexigenic genes under normal feeding condition. In addition, we found multiple gain and loss in expression correlations between the appetite-regulating genes, in zebrafish with impaired leptin signal, suggesting the presence of gene regulatory networks downstream of leptin signal in zebrafish brain. The results provide the first evidence for the effects of leptin signal on the transcription of various appetite-regulating genes in zebrafish brain, under different feeding conditions. Altogether, these transcriptional changes suggest an anorexigenic role for leptin signal, which is likely to be mediated through distinct set of appetite-regulating genes under different feeding conditions.
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| 3. |
- Ahi, Ehsan Pashay, et al.
(författare)
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Transcriptional study reveals a potential leptin-dependent gene regulatory network in zebrafish brain
- 2021
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Ingår i: Fish Physiology & Biochemistry. - : Springer Nature. - 0920-1742 .- 1573-5168. ; 47:4, s. 1283-1298
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Tidskriftsartikel (refereegranskat)abstract
- The signal mediated by leptin hormone and its receptor is a major regulator of body weight, food intake and metabolism. In mammals and many teleost fish species, leptin has an anorexigenic role and inhibits food intake by influencing the appetite centres in the hypothalamus. However, the regulatory connections between leptin and downstream genes mediating its appetite-regulating effects are still not fully explored in teleost fish. In this study, we used a loss of function leptin receptor zebrafish mutant and real-time quantitative PCR to assess brain expression patterns of several previously identified anorexigenic genes downstream of leptin signal under different feeding conditions (normal feeding, 7-day fasting, 2 and 6-h refeeding). These downstream factors include members of cart genes, crhb and gnrh2, as well as selected genes co-expressed with them based on a zebrafish co-expression database. Here, we found a potential gene expression network (GRN) comprising the abovementioned genes by a stepwise approach of identifying co-expression modules and predicting their upstream regulators. Among the transcription factors (TFs) predicted as potential upstream regulators of this GRN, we found expression pattern of sp3a to be correlated with transcriptional changes of the downstream gene network. Interestingly, the expression and transcriptional activity of Sp3 orthologous gene in mammals have already been implicated to be under the influence of leptin signal. These findings suggest a potentially conserved regulatory connection between leptin and sp3a, which is predicted to act as a transcriptional driver of a downstream gene network in the zebrafish brain.
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- Bergman, Eva, 1959-, et al.
(författare)
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Lax och öring i Klarälven - möjligheter för vild fisk och kvalité på odlad fisk : Slutrapport 2008-2012
- 2013
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Data från 1800-talet visar att fångsterna av lax och öring i både älv och sjö varit mycket högre än idag. Storskaliga dämmen, kraftigt fiske i Dejeforsen, nio kraftverk i den svenska delen av Klarälvens huvudfåra, och användandet av älven för timmerflottning har bidragit till detta. Efter att utsättning av kompensationsodlad fisk startade ökade fångsten igen, även om den fortfarande är låg.Fältundersökningar av vild laxsmolt visade att 16 % av smolten klarade sig hela vägen förbi de åtta kraftverken mellan Edebäck och Forshaga. Under studien var vattenföringen, och därmed spillet, lågt, vilket troligen bidragit till de höga förlusterna. Normalt spills det inte under hela smoltvandringsperioden, vilket är olyckligt.Lax och öring uppfödda under normala odlingsförhållanden är oftast större och fetare än vild fisk. Vi födde upp lax med olika fodertyper och fodermängder. Mängden föda påverkade laxens tillväxt och smoltmognad, och lax som fått fettfattigt foder var mest ”naturlik”. Den klarade också vandringen bäst, 80 % tog sig till Vänern medan 55 % av laxen som fått normalt eller lite foder. Bara 20 % av tidigt könsmogna hanar tog sig till Vänern.Rapporten avslutas med implikationer och förslag till åtgärder och fortsatta studier.
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- Calner, Mikael, et al.
(författare)
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A shoreline to deep basin correlation chart for the middle Silurian coupled extinction-stable isotopic event
- 2006
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Ingår i: GFF. - 2000-0863. ; 128, s. 79-84
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Tidskriftsartikel (refereegranskat)abstract
- A shoreline to deep basin correlation chart for the middle Silurian coupled extinction-stable isotopic event is presented. The chart is a first attempt to synthesise new stratigraphic, faunal and stable isotopic data, as well as diversity changes among organic-walled microplankton (acritarchs), from the Grotlingbo-1 and Hunninge-1 cores on Gotland (Sweden), along with previously published data from the Bartoszyce IG 1 core (Poland), the Grafenwarth section (Germany), and the Ruhnu (500) and Ohesaare cores (Estonia). Accordingly, the relative timing of biotic, sedimentary, and stable isotopic changes associated with the event can be studied in high stratigraphic resolution across a basin area of similar to 120 000 km(2) (in the epicontinental Baltic Basin) and further off the Silurian continental margin into the Rheic Ocean (Grafenwarth section). A graptolite biozonation is presented for the Late Wenlock of the Grotlingbo-1 core and the middle Silurian carbon isotope excursion (CIE) is for the first time detected in stratigraphically continuous sections on Gotland. It starts close above the LAD of Monograptus flemingii and peaks at delta C-13 values of 2.4 parts per thousand in the Grotlingbo-1 core and at 3.8 parts per thousand in the Hunninge-1 core. The correlation chart forms the basis for several important conclusions for the mid-Silurian event: (a) it is associated with major and synchronous sedimentary changes across the basin independent of palaeodepth, i.e., the entire marine realm, from shoreline to deep basin, was affected; (b) the onset of the CIE is within the latest part of a regressive systems tract and related to carbonate platform exposure and termination; (c) the CIE peak interval correlates with the early transgressive systems tract and the development of laminated strata in the deeper parts of epicontinental seas, as well as with increased accumulation of organic matter in even deeper basins; (d) the major diversity anomalies among planktonic and nektonic taxa precede or occur close to the onset of the CIE.
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| 32. |
- Jeuthe, Henrik, et al.
(författare)
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Evaluation of gamete quality indicators for Arctic charr Salvelinus alpinus
- 2019
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Ingår i: Aquaculture. - : Elsevier BV. - 0044-8486 .- 1873-5622. ; 504, s. 446-453
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Tidskriftsartikel (refereegranskat)abstract
- The reproductive performance of farmed Arctic charr exhibits substantial individual variation. The causes behind this variation have not yet been properly explained, despite the species relatively long history in aqua-culture. The aim of the present study was to provide better understanding of the issue by evaluating parent and gamete traits in relation to fertility and offspring viability under routine hatchery conditions. Are losses mainly due to failed fertilisation or mortality? Are maternal or paternal factor more predominant? The study covered sex hormone status of the broodstock, egg traits (egg size and wateriness of egg batches), milt traits (volume, density, and sperm motility characteristics), and symmetry of early cell division.We found that the majority of offspring loss occurred as embryo mortality, although a significant additional loss could be assigned fertilisation failure. Fertilisation and mortality rates were not inter-correlated. Neither of the evaluated egg traits, egg size and wateriness of newly stripped egg batches, proved to be useful indicators of egg quality. With regard to sperm traits, milt density as well as several computer assisted sperm analysis (CASA) parameters, i.e. swimming speed (VAP, VSL, and VCL) and beat cross frequency (BCF), were correlated with reproductive performance and could potentially be used as quality indicators for Arctic charr. Together, male 17,20β-P levels and BCF explained 69.5% of the between male variation in proportion of successfully eyed eggs.The results support previous indications that post-ovulatory aging of oocytes is contributing to the impairment of reproductive performance in farmed Arctic charr. In addition, a significant paternal factor to this impairment has been exposed. However, the cause and mechanism involved are still far from clear.
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- Kotrschal, Alexander, et al.
(författare)
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The mating brain : early maturing sneaker males maintain investment into the brain also under fast body growth in Atlantic salmon (Salmo salar)
- 2014
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Ingår i: Evolutionary Ecology. - : Springer Science and Business Media LLC. - 0269-7653 .- 1573-8477. ; 28:6, s. 1043-1055
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Tidskriftsartikel (refereegranskat)abstract
- It has been suggested that mating behaviours require high levels of cognitive ability. However, since investment into mating and the brain both are costly features, their relationship is likely characterized by energetic trade-offs. Empirical data on the subject remains equivocal. We investigated if early sexual maturation was associated with brain development in Atlantic salmon (Salmo salar), in which males can either stay in the river and sexually mature at a small size (sneaker males) or migrate to the sea and delay sexual maturation until they have grown much larger (anadromous males). Specifically, we tested how sexual maturation may induce plastic changes in brain development by rearing juveniles on either natural or ad libitum feeding levels. After their first season we compared brain size and brain region volumes across both types of male mating tactics and females. Body growth increased greatly across both male mating tactics and females during ad libitum feeding as compared to natural feeding levels. However, despite similar relative increases in body size, early maturing sneaker males maintained larger relative brain size during ad libitum feeding levels as compared to anadromous males and females. We also detected several differences in the relative size of separate brain regions across feeding treatments, sexes and mating strategies. For instance, the relative size of the cognitive centre of the brain, the telencephalon, was largest in sneaker males. Our data support that a large relative brain size is maintained in individuals that start reproduction early also during fast body growth. We propose that the cognitive demands during complex mating behaviours maintain a high level of investment into brain development in reproducing individuals.
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| 35. |
- Kubatova, Nina, et al.
(författare)
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Rapid Biophysical Characterization and NMR Spectroscopy Structural Analysis of Small Proteins from Bacteria and Archaea
- 2020
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Ingår i: ChemBioChem. - : Wiley. - 1439-4227 .- 1439-7633. ; 21:8, s. 1178-1187
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Tidskriftsartikel (refereegranskat)abstract
- © 2020 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA. Proteins encoded by small open reading frames (sORFs) have a widespread occurrence in diverse microorganisms and can be of high functional importance. However, due to annotation biases and their technically challenging direct detection, these small proteins have been overlooked for a long time and were only recently rediscovered. The currently rapidly growing number of such proteins requires efficient methods to investigate their structure–function relationship. Herein, a method is presented for fast determination of the conformational properties of small proteins. Their small size makes them perfectly amenable for solution-state NMR spectroscopy. NMR spectroscopy can provide detailed information about their conformational states (folded, partially folded, and unstructured). In the context of the priority program on small proteins funded by the German research foundation (SPP2002), 27 small proteins from 9 different bacterial and archaeal organisms have been investigated. It is found that most of these small proteins are unstructured or partially folded. Bioinformatics tools predict that some of these unstructured proteins can potentially fold upon complex formation. A protocol for fast NMR spectroscopy structure elucidation is described for the small proteins that adopt a persistently folded structure by implementation of new NMR technologies, including automated resonance assignment and nonuniform sampling in combination with targeted acquisition.
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| 36. |
- Lans, Linnea, 1975-, et al.
(författare)
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The effects of ration size on migration by hatchery-raised Atlantic salmon (Salmo salar) and brown trout (Salmo trutta)
- 2011
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Ingår i: Ecology of Freshwater Fish. - : Wiley. - 0906-6691 .- 1600-0633. ; 20:4, s. 548-557
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Tidskriftsartikel (refereegranskat)abstract
- The possibility to increase the proportion of migrating hatchery-reared smolts by reducing their food ration was studied. Lake-migrating, hatchery-reared salmon (Salmo salar) and trout (Salmo trutta) smolts were either fed normal rations, based on recommendations from the fish-farming industry, or reduced (15–20%) rations. They were released into the River Klarälven, western Sweden, and followed as they swam downstream to Lake Vänern, a distance of around 25 km. For both Atlantic salmon and brown trout, smolts fed a reduced ration migrated faster than fish fed a normal ration. Furthermore, a higher proportion of salmon smolts fed reduced rations migrated to the lake than fish fed normal rations in 2007 but not in 2006. This difference between years corresponded to greater treatment differences in size and smolt status in 2007 than in 2006. For trout, the proportion of migrating individuals and smolt development did not differ with ration size. Trout migrants fed a normal ration had a higher standard metabolic rate (SMR) than nonmigrants, whereas there was no difference in SMR between migrating and nonmigrating salmon. These results show that it is possible to use a reduced food ration to increase the migration speed of both Atlantic salmon and brown trout and to increase the proportion of migrating Atlantic salmon.
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- Norrgård, Johnny, 1976-, et al.
(författare)
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Effects of feeding regimes and early maturation on migratory behaviour of landlocked hatchery-reared Atlantic salmon Salmo salar smolts
- 2014
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Ingår i: Journal of Fish Biology. - : Wiley-Blackwell. - 0022-1112 .- 1095-8649. ; 85:4, s. 1060-1073
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Tidskriftsartikel (refereegranskat)abstract
- The migratory behaviour of hatchery-reared landlocked Atlantic salmon Salmo salar raised under three different feeding regimes was monitored through the lower part of the River Klarälven, Sweden. The smolts were implanted with acoustic transmitters and released into the River Klarälven, 25 km upstream of the outlet in Lake Vänern. Early mature males, which had matured the previous autumn, were also tagged and released. To monitor migration of the fish, acoustic receivers were deployed along the migratory route. The proportion of S. salar that reached Lake Vänern was significantly greater for fish fed fat-reduced feed than for fish given rations with higher fat content, regardless of ration size. Fish from the early mature male group remained in the river to a greater extent than fish from the three feeding regimes. Smolt status (degree of silvering), as visually assessed, did not differ among the feeding regime groups, and moreover, fully-silvered fish, regardless of feeding regime, migrated faster and had a greater migration success than fish with less developed smolt characteristics. Also, successful migrants had a lower condition factor than unsuccessful ones. These results indicate that the migration success of hatchery-reared S. smolts released to the wild can be enhanced by relatively simple changes in feeding regimes and by matching stocking time with smolt development.
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