| 1. |
- Elfwing, Magnus, et al.
(författare)
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Domestication Affected Heart Rate Regulation in Juvenile Chickens
- 2015
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- The domestication process in chickens has involved strong selection for productive traits. There is a broad understanding of phenotypic differences between domestic breeds and their ancestor, the Red Junglefowl (RJF), on fear related behaviors, genetic architecture, physiology and productive traits. Some of these characters can potentially be explained by changes in the activity of the autonomic nervous system. To address these questions we measured heart rate as a proxy for autonomic activity in the Red Junglefowl and compared it with two domestic strains, a broiler (BRO) (meat production) and a White Leghorn strain (HY) (egg production) at two and six weeks of age. Autonomic tones were pharmacologically manipulated in broilers to assess heart rate regulation during maturation. To investigate the dynamics of autonomic control animals were measured during baseline conditions and during acute stress.At two weeks of age baseline heart rate was high in all strains (RJF: 541.2±18.3, HY: 506.8±38.8, BRO: 456.0±22.3) and progressively decreased with age (RJF: 491.3±10.9, HY: 386.8±25.1, BRO:_296.8±26.9). BRO had a lower heart rate compared to RJF and HY, and the differences could not be explained by allometry alone. There was a domestication effect in BRO but not HY, which were in general more similar to RJF. These findings suggest that positive selection for somatic growth has changed heart rate regulation in broilers. During acute stress heart rate did not decrease with age in the same way than baseline values, which means that there is an increased scope for raising heart rate above baseline with age. At least in broilers the increased heart rate scope is due to a recruitment in adrenergic control in absence of a patent cholinergic tone.
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| 2. |
- Elfwing, Magnus, et al.
(författare)
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Early stress causes sex-specific, life-long changes in behaviour, levels of gonadal hormones, and gene expression in chickens
- 2015
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Ingår i: PLOS ONE. - : Public Library of Science. - 1932-6203. ; 10:5
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Tidskriftsartikel (refereegranskat)abstract
- Early stress can have long-lasting phenotypic effects. Previous research shows that male and female chickens differ in many behavioural aspects, and respond differently to chronic stress. The present experiment aimed to broadly characterize long-term sex differences in responses to brief events of stress experienced during the first weeks of life. Chicks from a commercial egg-laying hybrid were exposed to stress by inducing periods of social isolation during their first three weeks of life, followed by a broad behavioural, physiological and genomic characterization throughout life. Early stressed males, but not females, where more anxious in an open field-test, stayed shorter in tonic immobility and tended to have delayed sexual maturity, as shown by a tendency for lower levels of testosterone compared to controls. While early stressed females did not differ from non-stressed in fear and sexual maturation, they were more socially dominant than controls. The differential gene expression profile in hypothalamus was significantly correlated from 28 to 213 days of age in males, but not in females. In conclusion, early stress had a more pronounced long-term effect on male than on female chickens, as evidenced by behavioral, endocrine and genomic responses. This may either be attributed to inherent sex differences due to evolutionary causes, or possibly to different stress related selection pressures on the two sexes during commercial chicken breeding.
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| 3. |
- Elfwing, Magnus, et al.
(författare)
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Fetal development of baroreflex sensitivity: The chicken embryo as a case model
- 2011
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Ingår i: Respiratory Physiology & Neurobiology. - : Elsevier B.V.. - 1569-9048 .- 1878-1519. ; 178:1, s. 75-83
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Forskningsöversikt (refereegranskat)abstract
- The baroreflex is the main short term compensatory mechanism to buffer blood pressure changes and maintain circulatory homeostasis. Its ontogeny and importance during prenatal life is not fully understood so we used broiler chickens to investigate the maturation of the baroreflex in late incubation using a novel method that measured changes in heart rate during spontaneous fluctuations in blood pressure. Our results suggest that a baroreflex is already functional at d17 with no indication of further maturation in terms of sensitivity (gain at 17 d was 52.9 ± 8.3 and at 20 d 69.5 ± 16.2 ms kPa−1). The physiological relevance of these values is shown using data surrogation methods. Although the results contrast with the progressive baroreflex maturation indicated by the pharmacological method, we sustain that both methods provide information on baroreflex regulation. While the spontaneous method evaluates truly physiological (but small) pressure changes, the pharmacological method provides a more consistent and repetitive challenge for the reflex that requires a different recruitment of baroreflex effectors.
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| 4. |
- Elfwing, Magnus, et al.
(författare)
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The maturation of heart rate control in the Red Junglefowl (Gallus gallus)
- 2015
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Fetal development of autonomic cardiac control has been thoroughly investigated in chickens, but the maturation of the autonomic nervous system after hatching has gained little attention. At hatch the heart is under a feeble nervous control and there are indications suggesting a rapid maturation process during the first two weeks of postnatal life. We aimed to characterize the maturation by measuring heart rate at baseline and stressful conditions during the first 5 weeks of life in the Red Junglefowl and using autonomic antagonists to quantify the contribution of sympathetic and parasympathetic activity. We also compared the Red Junglefowl to the domestic broiler chickens at hatch to investigate the impact of domestication processes on heart rate regulation.During the first two postnatal weeks, baseline and stress heart rate progressively increased. After two weeks baseline heart rate decreased while heart rate during acute stress remained high. Adrenergic tone in Red Junglefowl increased as well early suggesting that the increase in heart rate was driven predominantly by adrenergic contributions. The adrenergic tone decreased by age after postnatal week one explaining the concomitant reduction in basal heart rate during this period. Broiler chickens possessed a strong cholinergic tone at hatch indicating that parasympathetic control has been favored perhaps due to heavy selection for somatic growth.
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| 5. |
- Elfwing, Magnus, 1980-
(författare)
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The Physiology of Chicken Domestication : Involvement of the HPA-axis and the Autonomic Nervous System
- 2015
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Domesticering är en urvalsprocess för önskvärda egenskaper hos djur som över tid förändrar deras utseende, beteende och genetik. Några exempel av djur som genomgått denna riktade avel är vargen, mufflon, uroxen, vildsvinet och den röda djungelhönan som vi idag känner som hunden, fåret, kon, grisen och slaktkycklingen.Några gemensamma egenskaper hos domesticerade djur är minskad rädsla för människor, och att de troligen har en högre stresstolerans jämfört med sina vilda förfäder. Det finns två huvudsakliga fysiologiska mekanismer som styr dessa responser, en hormonell och en nervös. Nervsystemet är i sin tur uppdelat i sympatiska och parasympatiska nervsystemet vilka har motsatta roller för kroppens funktioner. Under stress ger det sympatiska den så kallade ”Fight-and-flight”-responsen, och det parasympatiska aktiveras under vila och kallas ”rest-and-digest”-systemet. Det verkar troligt att domesticeringen agerat på dessa system för att minska rädsla och stress hos våra tamdjur.Den här avhandlingen studerar stressresponser hos höns. Dessa används i stor skala inom livsmedelsindustrin, slaktkycklingen för köttproduktion samt värphöns för äggproduktion. De har avlats hårt för snabb tillväxt och hög äggproduktion. En slaktkyckling ökar sin vikt till 50 gånger kläckvikten på sex veckor! Det sympatiska nervsystemet, samt stresshormoner, agerar för nedbrytande och energifrisläppande mekanismer, och det parasympatiska samt låg stress verkar för uppbyggande och energisparande mekanismer. Därför bör avel på låg stress och låg sympatisk aktivitet vara fördelaktigt för hög tillväxt.Experimenten i avhandlingen undersöker utvecklingen och mognaden av det autonoma nervsystemet hos kycklingar, domesticeringseffekter samt om stress tidigt i livet påverkar höns som vuxna. Vi fann att kycklingfoster redan vid 75 % av fosterutvecklingen har en funktionell parasympatisk stimulering på hjärtat och att dess inverkan ökar närmare kläckningen. Efter kläckning styrs hjärtat i huvudsak av det sympatiska nervsystemet och först vid ca 5 veckors ålder tycks systemet närma sig mognad. Vi hittade också domesticeringseffekter på hjärtfrekvensen, som styrs av det autonoma nervsystemet, hos framför allt slaktkycklingar som har en lägre hjärtfrekvens jämfört med djungelhönan.Tidigare studier har indikerat att en gen som uttrycker ett protein i hjärnan, i sympatiska nervsystemet samt i binjurarna har varit viktig för aveln på våra tamhöns. Denna gen, ADRA2C, styr till exempel frisläppningen av stresshormon från binjurarna. Vi undersökte eventuella domesticeringseffekter på denna gen med avseende på genuttryck, proteinmängd, beteenden, tillväxt samt äggproduktion, men trots att starka indikationer på att genen borde ha viktiga effekter, hittade vi inget stöd för att det.Det är inte enbart domesticering som kan ha inverkan på stress. Erfarenheter tidigt i livet kan förändra individens välmående som vuxen och även ha effekter på dess avkomma. Vi undersökte dessa aspekter hos höns som avlats för äggläggning genom att stressa dem under de första veckorna efter kläckning och följde dem till vuxen ålder. Fåglarna uppvisade livslång påverkan av sina erfarenheter och framför allt hanar var särskilt känsliga och fick långsiktiga förändringar i beteendet, försenad hormonfrisättning vid puberteten och förändrad genuttrycksprofil i hypotalamus. Dessa modifieringar kan vara ett resultat av att aveln riktat sig i huvudsak mot honor för deras äggläggningsförmåga, och att hanar därmed ej blivit lika motståndskraftiga mot stress tidigt i livet. Även hanar i avkomman påverkades av föräldrarnas tidiga erfarenheter. De hade förändrat beteende, ändrad hormonell stressrespons och förändrat genuttryck.Sammantaget visar resultaten hur nervsystemet utvecklas hos höns, samt att nervsystemet förändrats av den moderna aveln. Vidare kunde vi visa att stress tidigt i livet hos höns kan få långsiktiga effekter som involverar stressresponsen vilket kan få konsekvenser för djurets välfärd.
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| 6. |
- Elfwing, Magnus, et al.
(författare)
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The Strong Selective Sweep Candidate Gene ADRA2C Does Not Explain Domestication Related Changes In The Stress Response Of Chickens
- 2014
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Ingår i: PLOS ONE. - : Public Library of Science. - 1932-6203. ; 9:8, s. e103218-
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Tidskriftsartikel (refereegranskat)abstract
- Analysis of selective sweeps to pinpoint causative genomic regions involved in chicken domestication has revealed a strongselective sweep on chromosome 4 in layer chickens. The autoregulatory a-adrenergic receptor 2C (ADRA2C) gene is theclosest to the selective sweep and was proposed as an important gene in the domestication of layer chickens. The ADRA2Cpromoter region was also hypermethylated in comparison to the non-selected ancestor of all domesticated chicken breeds,the Red Junglefowl, further supporting its relevance. In mice the receptor is involved in the fight-or-flight response as itmodulates epinephrine release from the adrenals. To investigate the involvement of ADRA2C in chicken domestication, wemeasured gene expression in the adrenals and radiolabeled receptor ligand in three brain regions comparing the domesticWhite Leghorn strain with the wild ancestor Red Junglefowl. In adrenals ADRA2C was twofold greater expressed than therelated receptor gene ADRA2A, indicating that ADRA2C is the predominant modulator of epinephrine release but no straindifferences were measured. In hypothalamus and amygdala, regions associated with the stress response, and in striatum,receptor binding pIC50 values ranged between 8.1–8.4, and the level was not influenced by the genotyped allele. Becausechicken strains differ in morphology, physiology and behavior, differences attributed to a single gene may be lost in thenoise caused by the heterogeneous genetic background. Therefore an F10 advanced intercross strain between WhiteLeghorn and Red Junglefowl was used to investigate effects of ADRA2C alleles on fear related behaviors and fecundity. Wedid not find compelling genotype effects in open field, tonic immobility, aerial predator, associative learning or fecundity.Therefore we conclude that ADRA2C is probably not involved in the domestication of the stress response in chicken, and thestrong selective sweep is probably caused by selection of some unknown genetic element in the vicinity of the gene.
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| 7. |
- Goerlich, Vivian C., et al.
(författare)
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Transgenerational effects of early experience on acute stress reactions in behaviour, steroid hormones and gene expression in the precocial chicken
- 2012
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Ingår i: Hormones and Behavior. - : Elsevier BV. - 0018-506X .- 1095-6867. ; 61:5, s. 711-718
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Tidskriftsartikel (refereegranskat)abstract
- Stress during early life can profoundly influence an individual’s phenotype. Effects can manifest in the short-term as well as later in life and even in subsequent generations. Transgenerational effects of stress are potentially mediated via modulation of the hypothalamic-pituitary-adrenal axis (HPA) as well as epigenetic mechanisms causing heritable changes in gene expression. To investigate these pathways we subjected domestic chicks (Gallus gallus) to intermittent social isolation, food restriction, and temperature stress for the first three weeks of life. The early life stress resulted in a dampened corticosterone response to restraint stress in the parents and male offspring. Stress-specific genes, such as early growth response 1 (EGR1) and corticotropin releasing hormone receptor 1 (CRHR1), were upregulated when chicks were tested in the context of restraint stress, but not under baseline conditions. Treatment differences in gene expression were also correlated across generations which indicate transgenerational epigenetic inheritance, possibly mediated by differences in maternal yolk estradiol and testosterone. In an associative learning test early stressed birds made more correct choices suggesting a higher coping ability in stressful situations. This study is the first to show transgenerational effects of early life stress in a precocial species by combining behavioural, endocrinological, and transcriptomic measurements.
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| 8. |
- Gorokhova, Elena, et al.
(författare)
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Single and combined effects of hypoxia and contaminated sediments on the amphipod Monoporeia affinis in laboratory toxicity bioassays based on multiple biomarkers
- 2010
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Ingår i: Aquatic Toxicology. - : Elsevier BV. - 0166-445X .- 1879-1514. ; 99:2, s. 263-274
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Tidskriftsartikel (refereegranskat)abstract
- In estuaries, hypoxic conditions and pollution are among the major factors responsible for the declines in habitat quality, yet little is known about their combined effects on estuarine organisms. In this study, to investigate single and combined effects of hypoxia and contaminated sediment, the Baltic amphipod Monoporeia affinis was exposed for 5-9 days to four different combinations of oxygen conditions (moderate hypoxia vs. normoxia) and contamination (polluted vs. unpolluted sediments) at environmentally realistic levels. To detect oxidative stress, a suite of biomarkers was used - antioxidant enzymes [superoxide dismutases (SOD), catalase (CAT), and glutathione S-transferases (GST)], acetylcholinesterase (AChE), lipid peroxidation status (TBARS concentration), protein carbonyl content (PCC), and DNA strand breakage (DNA-SB). To assay effects at the organism level, we used RNA:DNA ratio as a proxy for growth and metabolic rate and mortality. There were significant increases in CAT and SOD activities and TBARS levels in response to both moderate hypoxia and contaminated sediment, while GST increased and AChE decreased in response to the contamination only. Significant positive correlations were observed among the antioxidant enzymes and between the enzyme activities and TBARS concentration, suggesting a complex response to the oxidative stress. No significant changes in PCC were recorded in any of the treatments. Furthermore, the negative effect of hypoxia on DNA integrity was significant; with frequency of DNA-SB increasing in animals exposed to hypoxia in contaminated sediment. Despite clear effect at the cellular and biochemical levels, no responses at the organism level were observed. Multivariate analyses of the dataset have allowed us to link exposure factors to individual biomarker responses. Of the potential biomarkers assessed in this study, CAT activity was found to be associated with hypoxia, while SOD, GST and AChE activities appear to predict best the effects of exposure to sediments containing several contaminants (e.g. heavy metals, PCBs and PAHs), and TBARS concentration is particularly indicative of combined effects of hypoxia and contamination. In addition to providing new knowledge on the combined effects of multiple stressors on estuarine organisms, the findings of the present study are also important to understand data from biomonitoring studies in the Baltic Sea and in other regions where multiple stress factors co-occur.
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| 9. |
- Jakobsson, Martin, et al.
(författare)
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Potential links between Baltic Sea submarine terraces and groundwater seeping
- 2020
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Ingår i: Earth Surface Dynamics. - : Copernicus GmbH. - 2196-6311 .- 2196-632X. ; 8:1, s. 1-15
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Tidskriftsartikel (refereegranskat)abstract
- Submarine groundwater discharge (SGD) influences ocean chemistry, circulation, and the spreading of nutrients and pollutants; it also shapes sea floor morphology. In the Baltic Sea, SGD was linked to the development of terraces and semicircular depressions mapped in an area of the southern Stockholm archipelago, Sweden, in the 1990s. We mapped additional parts of the Stockholm archipelago, areas in Blekinge, southern Sweden, and southern Finland using high-resolution multibeam sonars and sub-bottom profilers to investigate if the sea floor morphological features discovered in the 1990s are widespread and to further address the hypothesis linking their formation to SGD. Sediment coring and sea floor photography conducted with a remotely operated vehicle (ROV) and divers add additional information to the geophysical mapping results. We find that terraces, with general bathymetric expressions of about 1 m and lateral extents of sometimes > 100 m, are widespread in the surveyed areas of the Baltic Sea and are consistently formed in glacial clay. Semicircular depressions, however, are only found in a limited part of a surveyed area east of the island of Asko, southern Stockholm archipelago. While submarine terraces can be produced by several processes, we interpret our results to be in support of the basic hypothesis of terrace formation initially proposed in the 1990s; i.e. groundwater flows through siltier, more permeable layers in glacial clay to discharge at the sea floor, leading to the formation of a sharp terrace when the clay layers above seepage zones are undermined enough to collapse. By linking the terraces to a specific geologic setting, our study further refines the formation hypothesis and thereby forms the foundation for a future assessment of SGD in the Baltic Sea that may use marine geological mapping as a starting point. We propose that SGD through the submarine sea floor terraces is plausible and could be intermittent and linked to periods of higher groundwater levels, implying that to quantify the contribution of freshwater to the Baltic Sea through this potential mechanism, more complex hydrogeological studies are required.
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| 10. |
- Jensen, Bjarke, et al.
(författare)
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Coronary blood flow in the anesthetized American alligator (Alligator mississippiensis)
- 2016
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Ingår i: Comparative Biochemistry and Physiology A. - : Elsevier BV. - 1095-6433 .- 1531-4332. ; 191, s. 44-52
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Tidskriftsartikel (refereegranskat)abstract
- Coronary circulation of the heart evolved early within ectothermic vertebrates and became of vital importance to cardiac performance in some teleost fish, mammals and birds. In contrast, the role and function of the coronary circulation in ectothermic reptiles remains largely unknown. Here, we investigated the systemic and coronary arterial responses of five anesthetized juvenile American alligators (Alligator mississippiensis) to hypoxia, acetylcholine, adenosine, sodium nitroprusside, isoproterenol, and phenylephrine. We recorded electrocardiograms, monitored systemic blood pressure, blood flows in both aortae, and blood flow in a major coronary artery supplying most of the right ventricle. Coronary arterial blood flow was generally forward, but there was a brief retrograde flow during a ventricular contraction. Blood pressure was significantly changed in all conditions. Acetylcholine decreased coronary forward flow, but this response was confounded by the concomitant lowered work of the ventricles due to decreased heart rate and blood pressure. Coronary forward flow was poorly correlated with heart rate and mean arterial pressure across treatments. Overall changes in coronary forward flow, significant and not significant, were generally in the same direction as mean arterial pressure and ventricular power, approximated as the product of systemic cardiac output and mean arterial pressure. (c) 2015 Elsevier Inc. All rights reserved.
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