| 1. |
- Breves, J. P., et al.
(author)
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Hepatic insulin-like growth factor binding protein (igfbp) responses to food restriction in Atlantic salmon smolts
- 2016
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In: General and Comparative Endocrinology. - : Elsevier BV. - 0016-6480. ; 233, s. 79-87
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Journal article (peer-reviewed)abstract
- The growth hormone (Gh)/insulin-like growth-factor (Igf) system plays a central role in the regulation of growth in fishes. However, the roles of Igf binding proteins (Igfbps) in coordinating responses to food availability are unresolved, especially in anadromous fishes preparing for seaward migration. We assayed plasma Gh, Igf1, thyroid hormones and cortisol along with igfbp mRNA levels in fasted and fed Atlantic salmon (Salmo solar). Fish were fasted for 3 or 10 days near the peak of smoltification (late April to early May). Fasting reduced plasma glucose by 3 days and condition factor by 10 days. Plasma Gh, cortisol, and thyroxine (T-4) were not altered in response to fasting, whereas Igf1 and 3,5,3'-triiodo-L-thyronine (T-3) were slightly higher and lower than controls, respectively. Hepatic igfbp1b1, -1b2, -2a,-2b1 and -2b2 mRNA levels were not responsive to fasting, but there were marked increases in igfbp1a1 following 3 and 10 days of fasting. Fasting did not alter hepatic igf1 or igf2; however, muscle igf1 was diminished by 10 days of fasting. There were no signs that fasting compromised branchial ionoregulatory functions, as indicated by unchanged Na+/K+-ATPase activity and ion pump/transporter mRNA levels. We conclude that dynamic hepatic igfbp1a1 and muscle igf1 expression participate in the modulation of Gh/Igf signaling in smolts undergoing catabolism.
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| 2. |
- Fuentes, E. N., et al.
(author)
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The TORC1/P70S6K and TORC1/4EBP1 signaling pathways have a stronger contribution on skeletal muscle growth than MAPK/ERK in an early vertebrate: Differential involvement of the IGF system and atrogenes
- 2015
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In: General and Comparative Endocrinology. - : Elsevier BV. - 0016-6480. ; 210, s. 96-106
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Journal article (peer-reviewed)abstract
- Knowledge about the underlying mechanisms, particularly the signaling pathways that account for muscle growth in vivo in early vertebrates is still scarce. Fish (Paralichthys adspersus) were fasted for 3 weeks to induce a catabolic period of strong muscle atrophy. Subsequently, fish were refed for 2 weeks to induce compensatory muscle hypertrophy. During refeeding, the fish were treated daily with either rapamycin (TORC blocker), P098059 (MEK blocker), or PBS (V; vehicle), or were untreated (C; control). Rapamycin and P098059 differentially impaired muscle cellularity in vivo, growth performance, and the expression of growth-related genes, and the inhibition of TORC1 had a greater impact on fish muscle growth than the inhibition of MAPK. Blocking TORC1 inhibited the phosphorylation of P70S6K and 4EBP1, two downstream components activated by TORC1, thus affecting protein contents in muscle. Concomitantly, the gene expression in muscle of igf-1, 2 and igfbp-4, 5 was down-regulated while the expression of atrogin-1, murf-1, and igfbp-2, 3 was up-regulated. Muscle hypertrophy was abolished and muscle atrophy was promoted, which finally affected body weight. TORC2 complex was not affected by rapamycin. On the other hand, the PD98059 treatment triggered ERK inactivation, a downstream component activated by MEK. mRNA contents of igf-1 in muscle were down-regulated, and muscle hypertrophy was partially impaired. The present study provides the first direct data on the in vivo contribution of TORC1/P70S6K, TORC1/4EBP1, and MAPK/ERK signaling pathways in the skeletal muscle of an earlier vertebrate, and highlights the transcendental role of TORC1 in growth from the cellular to organism level. (C) 2014 Elsevier Inc. All rights reserved.
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| 3. |
- Gong, Ningping, 1979, et al.
(author)
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Impaired central leptin signaling and sensitivity in rainbow trout with high muscle adiposity
- 2016
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In: General and Comparative Endocrinology. - : Elsevier BV. - 0016-6480 .- 1095-6840. ; 235, s. 48-56
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Journal article (peer-reviewed)abstract
- The hormone leptin has been identified in all vertebrate classes, but its physiological roles in non-mammalian vertebrates are not well defined. To elucidate leptin regulation in energy homeostasis in a teleost fish species, this study compares hypothalamic and pituitary leptin signaling systems in energetically divergent rainbow trout lines selected for low (lean line, LL) and high (fat line, FL) muscle adiposity under feeding and starvation conditions. In fed fish, hypothalamic gene expression and protein density of the full-functional leptin receptor (LepRL), as well as a leptin binding protein (LepBP) expression, are lower in FL than LL fish. The FL fish have also lower activation of leptin-relevant signaling pathways involving protein kinase B (Akt) and extracellular signal-related kinase. These observations suggests impaired central leptin action in FL fish. During fasting, hypothalamic LepRL and LepBP expression, as well as active Akt levels are downregulated after one week, while pituitary LepRL expression is upregulated, in the LL fish only. After four weeks, hypothalamic LepRL protein levels return to normal levels in both fish lines and Akt is reactivated, although not to the same extent in FL as in LL fish, indicating that FL fish have low leptin sensitivity to nutritional changes. Neuropeptide Y and orexin expression is downregulated to similar levels in both fish lines after one-week fasting. The divergent leptin system profiles between the two fish lines demonstrate that phenotypic selection for high muscle adiposity affects leptin endocrinology, indicating regulatory roles for leptin in rainbow trout energy homeostasis. © 2016 Elsevier Inc.
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| 4. |
- Jansson, Erika, et al.
(author)
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Sex-dependent expression of anti-Müllerian hormone (amh) and amh receptor 2 during sex organ differentiation and characterization of the Müllerian duct development in Xenopus tropicalis
- 2016
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In: General and Comparative Endocrinology. - : Elsevier BV. - 0016-6480 .- 1095-6840. ; 229, s. 132-144
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Journal article (peer-reviewed)abstract
- Amphibian gonadal differentiation involves the action of sex steroids. Recent research indicates that the anti-Müllerian hormone (AMH) is involved in testicular development in some lower vertebrate species. For amphibians there is a lack of data on ontogenetic expression of the AMH receptor AMHR2/amhr2 and of progesterone receptors (PGRS/pgrs). Here we expand the knowledge on amphibian sex differentiation by characterizing ontogenetic mRNA levels of amh, amhr2, intracellular and membrane pgrs (ipgr and mpgr beta) and cytochrome P450 19a1 (cyp19a1) (ovarian marker) in the urogenital complex of the model species Xenopus (Silurana) tropicalis. Furthermore, we characterized the ontogenetic development of the Müllerian ducts (precursors of the female reproductive tract) histologically. The developmental period investigated spanned from beginning of gonadal differentiation, Nieuwkoop and Faber (NF) stage 51, to 4weeks post-metamorphosis. The Müllerian ducts were first observed at NF 64 in both sexes. Male-enhanced amh mRNA levels from NF 53/54 to 6days post-metamorphosis and female-enhanced cyp19a1 levels from NF 53 to 4weeks post-metamorphosis were noted. The sexually dimorphic mRNA level profile was more distinct for amh than for cyp19a1. The pgrs mRNA levels increased over the studied period and showed no sex differences. At later developmental stages, the amhr2 mRNA level was increased in putative females compared with males. Our findings suggest that AMH has a role in gonadal differentiation in X. tropicalis. We propose relative gonadal amh mRNA level as a testicular marker during early gonadal development in amphibians.
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| 5. |
- Johansson, Marcus, 1982, et al.
(author)
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Elevated plasma leptin levels of fasted rainbow trout decrease rapidly in response to feed intake
- 2015
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In: General and Comparative Endocrinology. - : Elsevier BV. - 0016-6480. ; 214, s. 24-29
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Journal article (peer-reviewed)abstract
- Leptin has an anorexigenic effect in fish, indicating a role in regulation of growth and energy homeostasis. The study aimed to further clarify the physiological role of leptin in rainbow trout, specifically its short-term response to feed intake after a period of fasting. Utilizing a salmonid leptin radioimmunoassay, the study demonstrates differences in plasma leptin levels in fishes with different nutritional status and at the onset of feeding. Some of the fasted fish were clearly in a state of anorexia, and did not initiate feeding during the 72 h refeeding period. For those fish that did initiate feeding, both previously fed and fasted, plasma leptin levels rapidly decreased during the first 24 h in correlation with increased amount of food reaching the gastrointestinal tract, while non-feeding individuals retained a high plasma leptin levels. The data indicate that the leptin-induced anorexic state is broken after onset of feeding and that the regulatory mechanisms leading to decreased plasma leptin levels are linked to nutrient levels.
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| 6. |
- Karlsson, Anna-Carin, et al.
(author)
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A domestication related mutation in the thyroid stimulating hormone receptor gene (TSHR) modulates photoperiodic response and reproduction in chickens
- 2016
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In: General and Comparative Endocrinology. - : Elsevier BV. - 0016-6480 .- 1095-6840. ; 228, s. 69-78
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Journal article (peer-reviewed)abstract
- The thyroid stimulating hormone receptor gene (TSHR) has been suggested to be a "domestication locus" in the chicken. A strong selective sweep over TSHR in domestic breeds together with significant effects of a mutation in the gene on several domestication related traits, indicate that the gene has been important for chicken domestication. TSHR plays a key role in the signal transduction of seasonal reproduction, which is characteristically less strict in domestic animals. We used birds from an advanced intercross line between ancestral Red Junglefowl (RJF) and domesticated White Leghorn (WL) to investigate effects of the mutation on reproductive traits as well as on TSHB, TSHR, DIO2 and DIO3 gene expression during altered day length (photoperiod). We bred chickens homozygous for either the mutation (d/d) or wild type allele (w/w), allowing assessment of the effect of genotype at this locus while also controlling for background variation in the rest of the genome. TSHR gene expression in brain was significantly lower in both did females and males and did females showed a faster onset of egg laying at sexual maturity than wow. Furthermore, did males showed a reduced testicular size response to decreased day length, and lower levels of TSHB and DIO3 expression. Additionally, purebred White Leghorn females kept under natural short day length in Sweden during December had active ovaries and lower levels of TSHR and DIO3 expression compared to Red Junglefowl females kept under similar conditions. Our study indicates that the TSHR mutation affects photoperiodic response in chicken by reducing dependence of seasonal reproduction, a typical domestication feature, and may therefore have been important for chicken domestication.
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| 7. |
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| 8. |
- Nässel, Dick R., et al.
(author)
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Insulin/IGF signaling and its regulation in Drosophila
- 2015
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In: General and Comparative Endocrinology. - : Elsevier BV. - 0016-6480 .- 1095-6840. ; 221, s. 255-266
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Journal article (peer-reviewed)abstract
- Taking advantage of Drosophila as a genetically tractable experimental animal much progress has been made in our understanding of how the insulin/IGF signaling (IS) pathway regulates development, growth, metabolism, stress responses and lifespan. The role of IIS in regulation of neuronal activity and behavior has also become apparent from experiments in Drosophila. This review briefly summarizes these functional roles of IIS, and also how the insulin producing cells (IPCs) are regulated in the fly. Furthermore, we discuss functional aspects of the spatio-temporal production of eight different insulin-like peptides (DILP1-8) that are thought to act on one known receptor (dInR) in Drosophila.
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| 9. |
- Ocampo Daza, Daniel, 1984-, et al.
(author)
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Evolution of the growth hormone, prolactin, prolactin 2 and somatolactin family
- 2018
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In: General and Comparative Endocrinology. - : ACADEMIC PRESS INC ELSEVIER SCIENCE. - 0016-6480 .- 1095-6840. ; 264, s. 94-112
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Journal article (peer-reviewed)abstract
- Growth hormone (GH), prolactin (PRL), prolactin 2 (PRL2) and somatolactin (SL) belong to the same hormone family and have a wide repertoire of effects including development, osmoregulation, metabolism and stimulation of growth. Both the hormone and the receptor family have been proposed to have expanded by gene duplications in early vertebrate evolution. A key question is how hormone-receptor preferences have arisen among the duplicates. The first step to address this is to determine the time window for these duplications. Specifically, we aimed to see if duplications resulted from the two basal vertebrate tetraploidizations (1R and 2R). GH family genes from a broad range of vertebrate genomes were investigated using a combination of sequence-based phylogenetic analyses and comparisons of synteny. We conclude that the PRL and PRL2 genes arose from a common ancestor in 1R/2R, as shown by neighboring gene families. No other gene duplicates were preserved from these tetraploidization events. The ancestral genes that would give rise to GH and PRL/PRL2 arose from an earlier duplication; most likely a local gene duplication as they are syntenic in several species. Likewise, some evidence suggests that SL arose from a local duplication of an ancestral GH/SL gene in the same time window, explaining the lack of similarity in chromosomal neighbors to GH, PRL or PRL2. Thus, the basic triplet of ancestral GH, PRL/ PRL2 and SL genes appear to be unexpectedly ancient. Following 1R/2R, only SL was duplicated in the teleost-specific tetraploidization 3R, resulting in SLa and SLb. These time windows contrast with our recent report that the corresponding receptor genes GHR and PRLR arose through a local duplication in jawed vertebrates and that both receptor genes duplicated further in 3R, which reveals a surprising asynchrony in hormone and receptor gene duplications.
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| 10. |
- Ocampo Daza, Daniel, 1984-, et al.
(author)
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Evolution of the receptors for growth hormone, prolactin, erythropoietin and thrombopoietin in relation to the vertebrate tetraploidizations
- 2018
-
In: General and Comparative Endocrinology. - : Elsevier BV. - 0016-6480 .- 1095-6840. ; 257, s. 143-160
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Journal article (peer-reviewed)abstract
- The receptors for the pituitary hormones growth hormone (GH), prolactin (PRL) and somatolactin (SL), and the hematopoietic hormones erythropoietin (EPO) and thrombopoietin (TPO), comprise a structurally related family in the superfamily of cytokine class-I receptors. GH, PRL and SL receptors have a wide variety of effects in development, osmoregulation, metabolism and stimulation of growth, while EPO and TPO receptors guide the production and differentiation of erythrocytes and thrombocytes, respectively. The evolution of the receptors for GH, PRL and SL has been partially investigated by previous reports suggesting different time points for the hormone and receptor gene duplications. This raises questions about how hormone-receptor partnerships have emerged and evolved. Therefore, we have investigated in detail the expansion of this receptor family, especially in relation to the basal vertebrate (1R, 2R) and teleost (3R) tetraploidizations. Receptor family genes were identified in a broad range of vertebrate genomes and investigated using a combination of sequence-based phylogenetic analyses and comparative genomic analyses of synteny. We found that 1R most likely generated EPOR/TPOR and GHR/PRLR ancestors; following this, 2R resulted in EPOR and TPOR genes. No GHR/PRLR duplicate seems to have survived after 2R. Instead the single GHR/PRLR underwent a local duplication sometime after 2R, generating separate syntenic genes for GHR and PRLR. Subsequently, 3R duplicated the gene pair in teleosts, resulting in two GHR and two PRLR genes, but no EPOR or TPOR duplicates. These analyses help illuminate the evolution of the regulatory mechanisms for somatic growth, metabolism, osmoregulation and hematopoiesis in vertebrates.
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