Formation of vitamin A in a freshwater fish. Isolation of retinoic acid.
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ABSTRACT:
SUBMITTER: Barua AB
PROVIDER: S-EPMC1164965 | biostudies-other | 1977 Jul
REPOSITORIES: biostudies-other
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Project description:Approximately 30 years ago, it was discovered that free-living bacteria isolated from cold ocean depths could produce polyunsaturated fatty acids (PUFA) such as eicosapentaenoic acid (EPA) (20:5n-3) or docosahexaenoic acid (DHA) (22:6n-3), two PUFA essential for human health. Numerous laboratories have also discovered that EPA- and/or DHA-producing bacteria, many of them members of the Shewanella genus, could be isolated from the intestinal tracts of omega-3 fatty acid-rich marine fish. If bacteria contribute omega-3 fatty acids to the host fish in general or if they assist some bacterial species in adaptation to cold, then cold freshwater fish or habitats should also harbor these producers. Thus, we undertook a study to see if these niches also contained omega-3 fatty acid producers. We were successful in isolating and characterizing unique EPA-producing strains of Shewanella from three strictly freshwater native fish species, i.e., lake whitefish (Coregonus clupeaformis), lean lake trout (Salvelinus namaycush), and walleye (Sander vitreus), and from two other freshwater nonnative fish, i.e., coho salmon (Oncorhynchus kisutch) and seeforellen brown trout (Salmo trutta). We were also able to isolate four unique free-living strains of EPA-producing Shewanella from freshwater habitats. Phylogenetic and phenotypic analyses suggest that one producer is clearly a member of the Shewanella morhuae species and another is sister to members of the marine PUFA-producing Shewanella baltica species. However, the remaining isolates have more ambiguous relationships, sharing a common ancestor with non-PUFA-producing Shewanella putrefaciens isolates rather than marine S. baltica isolates despite having a phenotype more consistent with S. baltica strains.
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Project description:Vitamin D and its derivatives, acting via the vitamin D receptor (VDR) and retinoic acid-related orphan receptors γ and α (RORγ and RORα), show anticancer properties. Since pathological conditions are characterized by disturbances in the expression of these receptors, in this study, we investigated their expression in ovarian cancers (OCs), as well as explored the phenotypic effects of vitamin D hydroxyderivatives and RORγ/α agonists on OC cells. The VDR and RORγ showed both a nuclear and a cytoplasmic location, and their expression levels were found to be reduced in the primary and metastatic OCs in comparison to normal ovarian epithelium, as well as correlated to the tumor grade. This reduction in VDR and RORγ expression correlated with a shorter overall disease-free survival. VDR, RORγ, and RORα were also detected in SKOV-3 and OVCAR-3 cell lines with increased expression in the latter line. 20-Hydroxy-lumisterol3 (20(OH)L3) and synthetic RORα/RORγ agonist SR1078 inhibited proliferation only in the OVCAR-3 line, while 20-hydroxyvitamin-D3 (20(OH)D3) only inhibited SKOV-3 cell proliferation. 1,25(OH)2D3, 20(OH)L3, and SR1078, but not 20(OH)D3, inhibited spheroid formation in SKOV-3 cells. In summary, decreases in VDR, RORγ, and RORα expression correlated with an unfavorable outcome for OC, and compounds targeting these receptors had a context-dependent anti-tumor activity in vitro. We conclude that VDR and RORγ expression can be used in the diagnosis and prognosis of OC and suggest their ligands as potential candidates for OC therapy.
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Project description:Fatty acids are widely used to study trophic interactions in food web assemblages. Generally, it is assumed that there is a very small modification of fatty acids from one trophic step to another, making them suitable as trophic biomarkers. However, recent literature provides evidence that many fishes possess genes encoding enzymes with a role in bioconversion, thus the capability for bioconversion might be more widespread than previously assumed. Nonetheless, empirical evidence for biosynthesis occurring in natural populations remains scarce. In this study, we investigated different feeding types of perch (Perca fluviatilis) that are specialized on specific resources with different levels of highly unsaturated fatty acids (HUFAs), and analyzed the change between HUFA proportions in perch muscle tissue compared to their resources. Perch showed matching levels to their resources for EPA, but ARA and especially DHA were accumulated. Compound-specific stable isotope analyses helped us to identify the origin of HUFA carbon. Our results suggest that perch obtain a substantial amount of DHA via bioconversion when feeding on DHA-poor benthic resources. Thus, our data indicate the capability of bioconversion of HUFAs in a natural freshwater fish population.
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Project description:This SuperSeries is composed of the SubSeries listed below.
2017-05-15 | GSE87814 | GEO
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Project description:Urinary bladder cancer is one of the leading malignancies worldwide, with the highest recurrence rates. A diet rich in vitamin A has proven to lower the risk of cancer, yet the molecular mechanisms underlying this effect are unknown. We found that vitamin A decreased urothelial atypia and apoptosis during early bladder carcinogenesis induced by N-butyl-N-(4-hydroxybutyl) nitrosamine (BBN). Vitamin A did not alter urothelial cell desquamation, differentiation, or proliferation rate. Genes like Wnt5a, involved in retinoic acid signaling, and transcription factors Pparg, Ppara, Rxra, and Hoxa5 were downregulated, while Sox9 and Stra6 were upregulated in early urothelial carcinogenesis. When a vitamin A rich diet was provided during BBN treatment, none of these genes was up- or downregulated; only Lrat and Neurod1 were upregulated. The lecithin retinol acyltransferase (LRAT) enzyme that produces all-trans retinyl esters was translocated from the cytoplasm to the nuclei in urothelial cells as a consequence of BBN treatment regardless of vitamin A rich diet. A vitamin A-rich diet altered retinoic acid signaling, decreased atypia and apoptosis of urothelial cells, and consequently diminished early urothelial carcinogenesis.
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