| 1. |
- Einarsdottir, Ingibjörg, 1951, et al.
(författare)
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Atlantic halibut growth hormone: structure and plasma levels of sexually mature males and females during photoperiod-regulated annual cycles
- 2002
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Ingår i: General and Comparative Endocrinology. - 0016-6480 .- 1095-6840. ; 127:1, s. 94-104
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Tidskriftsartikel (refereegranskat)abstract
- The main objectives of this study were to obtain the amino acid sequence of Atlantic halibut (Hippoglossus hippoglossus) growth hormone (hhGH) and compare it with other teleost species, to establish a radioimmunoassay to assess plasma hhGH levels and thus to gain information about possible biological functions and regulation by photoperiod. The hhGH gene was cloned and its amino acid sequence deduced from the cDNA. The mature hhGH protein consists of 186 amino acids. Comparison with other flatfish species as well as a species from a different order, the pufferfish, reveals that the sequence similarities of the mature hhGH with that of the barfin flounder, the Japanese flounder, the sole and the pufferfish are 99.5, 81.7, 74.2, and 65.2%, respectively. The sequence similarities appear to correctly reflect the gross phylogenetic relationships among these telcost species. A specific GH-RIA was developed for measurements of Atlantic halibut GH levels. Assessment of plasma GH levels in adult halibut revealed large gender differences, with GH levels frequently being an order of magnitude higher in males than females. The mean (+/-SEM) plasma GH for males kept on normal annual photoperiod were 25.2 +/- 6.11 ng ml(-1) and for females were 5.14 +/- 1.94 ng ml(-1). It appears likely that plasma growth hormone levels in Atlantic halibut can be inversely correlated to growth and metabolism. Shifting of the annual photoperiod cycles demonstrated that photoperiod in not a regulator of plasma GH levels in the Atlantic halibut. but further research is needed to assess whether GH plays a role in the reproduction of this marine teleost species. (C) 2002 Elsevier Science (USA). All rights reserved.
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| 2. |
- von Hofsten, Jonas, et al.
(författare)
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Fushi tarazu factor-1 mRNA and protein is expressed in steroidogenic and cholesterol metabolising tissues during different life stages in Arctic char (Salvelinus alpinus)
- 2003
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Ingår i: General and Comparative Endocrinology. - : Elsevier. - 0016-6480 .- 1095-6840. ; 132:1, s. 96-102
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Tidskriftsartikel (refereegranskat)abstract
- Fushi tarazu factor-1 (FTZ-F1) genes belong to the nuclear receptor family 5A (NR5A). The distribution pattern of NR5A genes in teleosts suggests that they control functions separate to, or in addition to, those of other vertebrates. In mammals NR5A1 genes, including steroidogenic factor-1 (SF-1), are primarily involved in steroidogenesis. NR5A2 contain the alpha-fetoprotein transcription factor (FTF) genes, which protect mammalian embryos against maternal estrogens, and are involved in cholesterol transfer and metabolism. In this study we have analysed the expression of two Arctic char FTZ-F1 forms belonging to the NR5A2 group. The expression starts during early development and the transcripts are present in embryonic liver/pancreas and gonadal regions. The genes are up-regulated during embryogenesis as the embryo develops towards hatch, as shown by increased mRNA and protein levels. In adult Arctic char the FTZ-F1 forms are primarily located to tissues involved in steroidogenesis as well as cholesterol metabolism. Thus, a division of NR5A into SF-1 (NR5A1) and FTF (NR5A2) specific functions does not appear to have occurred in teleosts.
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| 3. |
- von Hofsten, Jonas, et al.
(författare)
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Fushi tarazu factor-1 mRNA and protein is expressed in steroidogenic and cholesterol metabolising tissues during different life stages in Arctic char (Salvelinus alpinus)
- 2003
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Ingår i: General and Comparative Endocrinology. - : Elsevier BV. - 0016-6480 .- 1095-6840. ; 132:1, s. 96-102
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Tidskriftsartikel (refereegranskat)abstract
- Fushi tarazu factor-1 (FTZ-F1) genes belong to the nuclear receptor family 5A (NR5A). The distribution pattern of NR5A genes in teleosts suggests that they control functions separate to, or in addition to, those of other vertebrates. In mammals NR5A1 genes, including steroidogenic factor-1 (SF-1), are primarily involved in steroidogenesis. NR5A2 contain the alpha-fetoprotein transcription factor (FTF) genes, which protect mammalian embryos against maternal estrogens, and are involved in cholesterol transfer and metabolism. In this study we have analysed the expression of two Arctic char FTZ-F1 forms belonging to the NR5A2 group. The expression starts during early development and the transcripts are present in embryonic liver/pancreas and gonadal regions. The genes are up-regulated during embryogenesis as the embryo develops towards hatch, as shown by increased mRNA and protein levels. In adult Arctic char the FTZ-F1 forms are primarily located to tissues involved in steroidogenesis as well as cholesterol metabolism. Thus, a division of NR5A into SF-1 (NR5A1) and FTF (NR5A2) specific functions does not appear to have occurred in teleosts.
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| 4. |
- Berg, A. H., et al.
(författare)
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Regulation of Arctic char (Salvelinus alpinus) egg shell proteins and vitellogenin during reproduction and in response to 17β-estradiol and cortisol
- 2004
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Ingår i: General and Comparative Endocrinology. - : Elsevier. - 0016-6480 .- 1095-6840. ; 135:3, s. 276-285
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Tidskriftsartikel (refereegranskat)abstract
- Estrogens induce both vitellogenin (Vtg) and egg shell (zona pellucida; ZP) protein synthesis in salmonids. However, while Vtg is strictly under estrogenic control, recent reports suggest that additional mechanisms are involved in ZP protein synthesis. During sexual maturation both estrogen and glucocorticoid levels increase in the circulation of female fish. As glucocorticoids have been shown to interfere with Vtg induction in fish we investigated whether cortisol (F) had similar effects on ZP regulation. In the present study we determined both the natural variation in Vtg and ZP during an annual reproductive cycle in female Arctic char (Salvelinus alpinus), and the effect of co-treatment of juvenile Arctic char with 17β-estradiol (E2) and F. During sexual maturation the expression of Vtg and ZP correlated to plasma levels of E2 and F. Determination of Vtg and ZP protein levels following co-treatment with E2 and F showed that F antagonized E2 induction of Vtg. However, F was observed to potentiate the expression of ZP protein in the same fish. These results indicate that in Arctic char Vtg and ZP proteins are not regulated by the same mechanisms and suggest that ZP protein expression does not necessarily imply exposure to estrogenic compounds alone, and may thus not be ideally suited as a biomarker of exposure to estrogenic compounds.
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| 5. |
- Blixt, Martin, 1977-, et al.
(författare)
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Characterization of β-cell function of pancreatic islets isolated from bank voles developing glucose intolerance/diabetes : an animal model showing features of both type 1 and type 2 diabetes mellitus, and a possible role of the Ljungan virus
- 2007
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Ingår i: General and Comparative Endocrinology. - : Elsevier BV. - 0016-6480 .- 1095-6840. ; 154:1-3, s. 41-47
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Tidskriftsartikel (refereegranskat)abstract
- Bank voles (Clethrionomys glareolus) kept in captivity develop diabetes mellitus to a significant extent. Also in wild bank voles, elevated blood glucose has been observed. A newly isolated picornavirus named Ljungan virus (LV) has been found in the pancreas of these bank voles. Moreover, LV infection in combination with environmental factors may cause glucose intolerance/diabetes (GINT/D) in normal mice. The aim of the present study was to investigate the functional characteristics of pancreatic islets, isolated from bank voles, bred in the laboratory but considered LV infected. About 20% of all males and females were classified as GINT/D following a glucose tolerance test. Of these animals the majority had become diabetic by 20 weeks of age, with a tendency towards an earlier onset in the males. GINT/D animals had increased serum insulin levels. Islets were tested on the day of isolation (day 0) and after 1 week of culture for their insulin content and their capacity to synthesize (pro)insulin, secrete insulin and metabolize glucose. Functional differences could be observed between normal and GINT/D animals as well as between genders. An elevated basal insulin secretion was observed on day 0 indicating β-cell dysfunction among islets isolated from diabetic males. In vitro culture could reverse some functional changes. The increased serum insulin level and the increased basal islet insulin secretion may suggest that the animals had developed a type 2 diabetes-like condition. It is likely that the putative stress imposed in the laboratory, maybe in combination with LV infection, can lead to an increased functional demand on the β-cells.
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| 6. |
- Brunström, Björn, et al.
(författare)
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Effects of estrogens on sex differentiation in Japanese quail and chicken
- 2009
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Ingår i: General and Comparative Endocrinology. - : Elsevier BV. - 0016-6480 .- 1095-6840. ; 163:1-2, s. 97-103
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Tidskriftsartikel (refereegranskat)abstract
- Estrogen production by the female avian embryo induces development of a female phenotype of the reproductive organs whereas the low estrogen concentration in the male embryo results in a male phenotype. Treatment of female embryos with exogenous estrogens disrupts Müllerian duct development resulting in malformations and impaired oviductal function. Exposure of male embryos to estrogens results in ovotestis formation and persisting Müllerian ducts in the embryos and testicular malformations, reduced semen production and partially developed oviducts in the adult bird. Furthermore, studies in Japanese quail show that the male copulatory behavior is impaired by embryonic estrogen treatment. Results from our experiments with selective agonists for ERalpha and ERbeta suggest that the effects of estrogens on the reproductive organs are mediated via activation of ERalpha. Abundant expression of ERalpha mRNA was shown in gonads and Müllerian ducts of early Japanese quail embryos. Both ERalpha and ERbeta transcripts were detected by real-time PCR in early embryo brains of Japanese quail indicating that both receptors may be involved in sex differentiation of the brain. However, in 9-day-old quail embryo brains in situ hybridization showed expression of ERbeta mRNA, but not of ERalpha mRNA, in the medial preoptic nucleus (POM) and the bed nucleus of the stria terminalis (BSTm), areas implicated in copulatory behavior of adult male quail. Furthermore, embryonic treatment with the selective ERalpha agonist propyl pyrazol triol (PPT) had no effect on the male copulatory behavior. These results suggest that ERbeta may be important for the effects of estrogens on brain differentiation.
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| 7. |
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| 8. |
- Cardoso, João C R, et al.
(författare)
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New insights into the evolution of vertebrate CRH (corticotropin-releasing hormone) and invertebrate DH44 (diuretic hormone 44) receptors in metazoans
- 2014
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Ingår i: General and Comparative Endocrinology. - : Elsevier BV. - 0016-6480 .- 1095-6840. ; 209:SI, s. 162-170
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Tidskriftsartikel (refereegranskat)abstract
- The corticotropin releasing hormone receptors (CRHR) and the arthropod diuretic hormone 44 receptors (DH44R) are structurally and functionally related members of the G protein-coupled receptors (GPCR) of the secretin-like receptor superfamily. We show here that they derive from a bilaterian predecessor. In protostomes, the receptor became DH44R that has been identified and functionally characterised in several arthropods but the gene seems to be absent from nematode genomes. Duplicate DH44R genes (DH44 R1 and DH44R2) have been described in some arthropods resulting from lineage-specific duplications. Recently, CRHR-DH44R-like receptors have been identified in the genomes of some lophotrochozoans (molluscs, which have a lineage-specific gene duplication, and annelids) as well as representatives of early diverging deuterostomes. Vertebrates have previously been reported to have two CRHR receptors that were named CRHR1 and CRHR2. To resolve their origin we have analysed recently assembled genomes from representatives of early vertebrate divergencies including elephant shark, spotted gar and coelacanth. We show here by analysis of synteny conservation that the two CRHR genes arose from a common ancestral gene in the early vertebrate tetraploidizations (2R) approximately 500 million years ago. Subsequently, the teleost-specific tetraploidization (3R) resulted in a duplicate of CRHR1 that has been lost in some teleost lineages. These results help distinguish orthology and paralogy relationships and will allow studies of functional conservation and changes during evolution of the individual members of the receptor family and their multiple native peptide agonists.
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| 9. |
- Elofsson, Ulf, et al.
(författare)
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Intermale competition in sexually mature arctic charr : effects on brain monoamines, endocrine stress responses, sex hormone levels, and behavior.
- 2000
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Ingår i: General and Comparative Endocrinology. - : Elsevier. - 0016-6480 .- 1095-6840. ; 118:3, s. 450-60
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Tidskriftsartikel (refereegranskat)abstract
- Sexually mature Arctic charr (Salvelinus alpinus) males were allowed to interact in pairs for 4 days in the absence of females. Agonistic behavior was quantified, and at the end of the experiment, plasma levels of glucose, cortisol, testosterone (T), 11-ketotestosterone (11-KT), and 17alpha,20beta-dihydroxy-4-pregnen-3-one (17alpha, 20beta-P) were determined alongside brain concentrations of serotonin (5-HT), 5-hydroxyindoleacetic acid (5-HIAA, the major 5-HT metabolite), dopamine (DA), and 3,4-dihydroxyphenylacetic acid (DOPAC, a major DA metabolite). Plasma cortisol and glucose were significantly elevated in subordinate fish, and the number of aggressive acts received showed positive correlations with plasma levels of glucose on day 1, during the development of the dominance relationship, and of cortisol on day 4, when the dominance relationship was established. In contrast, plasma concentrations of T and 11-KT were significantly higher in dominant than in subordinate males, and there was a similar tendency in plasma concentrations of 17alpha,20beta-P. Further, plasma levels of these gonadal steroids were correlated with the number of aggressive acts performed on day 4, but not with the number of aggressive acts received. The plasma cortisol concentrations did not correlate with either 5-HIAA:5-HT or DOPAC:DA ratios in any of the brain parts analyzed. Plasma glucose levels showed positive correlations with brain 5-HIAA:5-HT ratios. Negative correlations were observed between 5-HIAA:5-HT ratios in the optic tectum and between plasma levels of T, 11-KT, and 17alpha,20beta-P. Telencephalic DOPAC/DA ratios displayed a negative correlation with plasma levels of T, 11-KT, and 17alpha,20beta-P, but only in dominant males.
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| 10. |
- Fahlman, Åsa
(författare)
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Cortisol and corticosterone independence in cortisol-dominant wildlife
- 2012
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Ingår i: General and Comparative Endocrinology. - : Elsevier BV. - 0016-6480 .- 1095-6840. ; 177, s. 113-119
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Tidskriftsartikel (refereegranskat)abstract
- Species have traditionally been defined as cortisol-dominant or corticosterone-dominant, depending on the glucocorticoid that is reported. To assess the degree of covariance versus independence between cortisol and corticosterone, 245 serum samples belonging to 219 individuals from 18 cortisol-dominant, non-domesticated species (6 mammalian orders) were compared by mass spectrometry. In these samples, which were elevated above baseline, concentration ranges were overlapping for cortisol and corticosterone although cortisol was dominant in every sample except one of 17 bighorn sheep with a corticosterone-biased cortisol-to-corticosterone ratio of 0.17. As expected, cortisol and corticosterone were strongly associated among species (r(2) = 0.8; species with high absolute cortisol tend to have high absolute corticosterone concentrations), with wide variation in the species-average cortisol-to-corticosterone ratio (range 7.5-49) and an even wider ratio range across individuals (0.2-341). However, only 9 out of 13 species with >7 individuals showed a positive association between cortisol and corticosterone among individuals, and repeated measures of the cortisol-to-corticosterone ratio within individuals were weakly associated (CV range 3-136%). We conclude that corticosterone, although at lower concentrations, has the potential to signal independently of cortisol, and should be included in integrated endocrine models of stress responses. (C) 2012 Elsevier Inc. All rights reserved.
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