Role of EPAC in cAMP-Mediated Actions in Adrenocortical Cells

Adrenocorticotropic hormone regulates adrenal steroidogenesis mainly via the intracellular signaling molecule cAMP. The effects of cAMP are principally relayed by activating protein kinase A (PKA) and the more recently discovered exchange proteins directly activated by cAMP 1 and 2 (EPAC1 and EPAC2). While the intracellular roles of PKA have been extensively studied in steroidogenic tissues, those of EPACs are only emerging. EPAC1 and EPAC2 are encoded by the genes RAPGEF3 and RAPGEF4, respectively. Whereas EPAC1 is ubiquitously expressed, the expression of EPAC2 is more restricted, and typically found in endocrine tissues. Alternative promoter usage of RAPGEF4 gives rise to three different isoforms of EPAC2 that vary in their N-termini (EPAC2A, EPAC2B, and EPAC2C) and that exhibit distinct expression patterns. EPAC2A is expressed in the brain and pancreas, EPAC2B in steroidogenic cells of the adrenal gland and testis, and EPAC2C has until now only been found in the liver. In this review, we discuss current knowledge on EPAC expression and function with focus on the known roles of EPAC in adrenal gland physiology

Comparative absorption and tissue distribution of 14C-benzo(a)pyrene and 14C-phenanthrene in the polar cod (Boreogadus saida) following oral administration

Published version. Source at http://doi.org/10.1007/s00300-015-1816-7.The Arctic is an important sink for organic pollutants such as polycyclic aromatic hydrocarbons (PAHs) long-range transported from industrial regions. With the retreat of sea ice and increasing anthropogenic activities such as the oil and gas industries, local sources of PAHs are expected to increase both through operational and accidental discharges. There is a need to increase our knowledge concerning the uptake and distribution of organic pollutants, in particular PAHs, to evaluate the risk these toxic compounds may represent for Arctic species. The absorption and tissue distribution of 14C-benzo(a)pyrene (BaP) and 14C-phenanthrene (Phen) were studied in the polar cod (Boreogadus saida), a key Arctic species. After a single oral dose of BaP (1.15 ± 0.36 mg/kg fish) or Phen (0.40 ± 0.12 mg/kg fish), corresponding to 0.12 ± 0.03 mCi/kg fish, the tissue distribution was followed through 30 days by means of whole-body autoradiography and liquid scintillation counting of liver and bile. For both compounds, radiolabeling was mainly present in the bile and the intestines throughout the study period. Phen-derived radioactivity, however, appeared to be more systemically distributed compared to BaP. Furthermore, a far higher amount of irreversibly bound BaP-derived radioactivity was present in the intestinal mucosa compared to Phen, indicating a more extensive formation of reactive intermediates from the former compared with the latter. Liquid scintillation counting confirmed that radioactivity was present in the liver at all time points for both groups although the levels were low in the BaP group. These results strongly indicated that both compounds and/or their metabolites undergo enterohepatic circulation

Deltamethrin resistance in the salmon louse, Lepeophtheirus salmonis (Krøyer): Maternal inheritance and reduced apoptosis

publishedVersio

Mutations in voltage-gated sodium channels from pyrethroid resistant salmon lice (Lepeophtheirus salmonis)

Background Parasitic salmon lice (Lepeophtheirus salmonis) cause high economic losses in Atlantic salmon farming. Pyrethroids, which block arthropod voltage‐gated sodium channels (Nav1), are used for salmon delousing. However, pyrethroid resistance is common in L. salmonis. The present study characterised Nav1 homologues in L. salmonis in order to identify channel mutations associated to resistance, called kdr (knockdown) mutations. Results Genome scans identified three L. salmonis Nav1 homologues, LsNav1.1, LsNav1.2 and LsNav1.3. Arthropod kdr mutations map to specific Nav1 regions within domains DI‐III, namely segments S5 and S6 and the linker helix connecting S4 and S5. The above channel regions were amplified by RT‐PCR and sequenced in deltamethrin‐susceptible and deltamethrin‐resistant L. salmonis. While LsNav1.1 and LsNav1.2 lacked nucleotide polymorphisms showing association to resistance, LsNav1.3 showed a non‐synonymous mutation in S5 of DII occurring in deltamethrin‐resistant parasites. The mutation is homologous to a previously described kdr mutation (I936V, numbering according to Musca domestica Vssc1) and was present in two pyrethroid‐resistant L. salmonis strains (allele frequencies of 0.800 and 0.357), but absent in two pyrethroid‐susceptible strains. Conclusions The present study indicates that a kdr‐mutation in LsNaV 1.3 may contribute to deltamethrin resistance in L. salmonis

Protected sampling is preferable in bronchoscopic studies of the airway microbiome

The aim was to evaluate susceptibility of oropharyngeal contamination with various bronchoscopic sampling techniques. 67 patients with obstructive lung disease and 58 control subjects underwent bronchoscopy with small-volume lavage (SVL) through the working channel, protected bronchoalveolar lavage (PBAL) and bilateral protected specimen brush (PSB) sampling. Subjects also provided an oral wash (OW) sample, and negative control samples were gathered for each bronchoscopy procedure. DNA encoding bacterial 16S ribosomal RNA was sequenced and bioinformatically processed to cluster into operational taxonomic units (OTU), assign taxonomy and obtain measures of diversity. The proportion of Proteobacteria increased, whereas Firmicutes diminished in the order OW, SVL, PBAL, PSB (p<0.01). The alpha-diversity decreased in the same order (p<0.01). Also, beta-diversity varied by sampling method (p<0.01), and visualisation of principal coordinates analyses indicated that differences in diversity were smaller between OW and SVL and OW and PBAL samples than for OW and the PSB samples. The order of sampling (left versus right first) did not influence alpha- or beta-diversity for PSB samples. Studies of the airway microbiota need to address the potential for oropharyngeal contamination, and protected sampling might represent an acceptable measure to minimise this problem.publishedVersio

Mice depleted for Exchange Proteins Directly Activated by cAMP (Epac) exhibit irregular liver regeneration in response to partial hepatectomy

The exchange proteins directly activated by cAMP 1 and 2 (Epac1 and Epac2) are expressed in a cell specific manner in the liver, but their biological functions in this tissue are poorly understood. The current study was undertaken to begin to determine the potential roles of Epac1 and Epac2 in liver physiology and disease. Male C57BL/6J mice in which expression of Epac1 and/or Epac2 are deleted, were subjected to partial hepatectomy and the regenerating liver was analyzed with regard to lipid accumulation, cell replication and protein expression. In response to partial hepatectomy, deletion of Epac1 and/or Epac2 led to increased hepatocyte proliferation 36 h post surgery, and the transient steatosis observed in wild type mice was virtually absent in mice lacking both Epac1 and Epac2. The expression of the protein cytochrome P4504a14, which is implicated in hepatic steatosis and fibrosis, was substantially reduced upon deletion of Epac1/2, while a number of factors involved in lipid metabolism were significantly decreased. Moreover, the number of Küpffer cells was affected, and Epac2 expression was increased in the liver of wild type mice in response to partial hepatectomy, further supporting a role for these proteins in liver function. This study establishes hepatic phenotypic abnormalities in mice deleted for Epac1/2 for the first time, and introduces Epac1/2 as regulators of hepatocyte proliferation and lipid accumulation in the regenerative process

Atlantic Salmon Reovirus Infection Causes a CD8 T Cell Myocarditis in Atlantic Salmon (Salmo salar L.)

Heart and skeletal inflammation (HSMI) of farmed Atlantic salmon (Salmo salar L.) is a disease characterized by a chronic myocarditis involving the epicardium and the compact and spongious part of the heart ventricle. Chronic myositis of the red skeletal muscle is also a typical finding of HSMI. Piscine reovirus (PRV) has been detected by real-time PCR from farmed and wild salmon with and without typical changes of HSMI and thus the causal relationship between presence of virus and the disease has not been fully determined [1]. In this study we show that the Atlantic salmon reovirus (ASRV), identical to PRV, can be passaged in GF-1 cells and experimental challenge of naïve Atlantic salmon with cell culture passaged reovirus results in cardiac and skeletal muscle pathology typical of HSMI with onset of pathology from 6 weeks, peaking by 9 weeks post challenge. ASRV replicates in heart tissue and the peak level of virus replication coincides with peak of heart lesions. We further demonstrate mRNA transcript assessment and in situ characterization that challenged fish develop a CD8+ T cell myocarditis

Association studies of up to 1.2 million individuals yield new insights into the genetic etiology of tobacco and alcohol use

Tobacco and alcohol use are leading causes of mortality that influence risk for many complex diseases and disorders 1 . They are heritable 2,3 and etiologically related 4,5 behaviors that have been resistant to gene discovery efforts 6–11 . In sample sizes up to 1.2 million individuals, we discovered 566 genetic variants in 406 loci associated with multiple stages of tobacco use (initiation, cessation, and heaviness) as well as alcohol use, with 150 loci evidencing pleiotropic association. Smoking phenotypes were positively genetically correlated with many health conditions, whereas alcohol use was negatively correlated with these conditions, such that increased genetic risk for alcohol use is associated with lower disease risk. We report evidence for the involvement of many systems in tobacco and alcohol use, including genes involved in nicotinic, dopaminergic, and glutamatergic neurotransmission. The results provide a solid starting point to evaluate the effects of these loci in model organisms and more precise substance use measures

Stimulation of the serotonergic activity and suppression of aggression by L-tryptophan treatment in juvenile Atlantic cod (Gadus morhua)

Abstract The interest for commercial rearing of Atlantic cod (Gadus morhua) has grown over the last decades. However, heterogeneous growth and cannibalism during early juvenile stages causes serious financial losses. Generally in fishes, dominance based hierarchies leads to heterogeneous growth. Furthermore, a close relationship between cannibalism and heterogeneous growth has been observed. Moreover, it has been demonstrated that an increase in serotonergic activity is assosiated with suppressed aggressive behaviour in various vertebrate species. For instance, dietary feed supplemented with the serotonin precursor tryptophan (TRP) has been shown to suppress aggressive behaviour in rainbow trout. However, little is known about the social organization, aggressive behaviour and the the underlying neural mechanisms of intraspesific competition in juvenile cod. To develope a method for quantifying aggressive behaviour in juvenile cod, two different protocols were tested, and the effects of dietary TRP supplementation on aggression was investigated. The study also included an analasys of the effects of dietary TRP supplementation on brain serotonergic activity (indexed by the ratio between the serotonin metabolite 5-hydroxyindoleacetic acid, and serotonin). Following an initial control period, fish were given TRP supplemented feed for seven days. This resulted in a decrease in aggressive behaviour when it was quantified with daily pairwise interactions (experiment 1). Furthermore, TRP treatment resulted in an increase in serootnergic activity (experiment 2). However, when aggression was quantified by a resident-intruder test protocol (experiment 2), no effects on aggression of dietary TRP supplementation was observed. The absence of a measurable suppression of aggression in experiment 2 could be related to stress induced by the resident-intruder test, suggesting that this protocol is less suitable for detecting changes in aggressive behaviour in juvenile cod. In conclusion, this study shows that juvenile cod are highly aggressive, and that dietary TRP supplementation can suppress this behaviour. Thus, TRP supplementation may offer a presumptive strategy for decreasing aggression and associated problems, such as size heterogeneity and cannibalism, in cod rearing

Kulturårboka

GEORG ARNESTAD (RED. ) (1994) KULTURÅRBOKA, OSLO: DET NORSKE SAMLAGET