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Røys EÅ, Guldhaug NA, Viste K, Jones GD, Alaour B, Sylte MS, Torsvik J, Kellmann R, Strand H, Theodorsson E, Marber M, Omland T, Aakre KM. Sex Hormones and Adrenal Steroids: Biological Variation Estimated Using Direct and Indirect Methods. Clin Chem 2023; 69:100-109. [PMID: 36373220 DOI: 10.1093/clinchem/hvac175] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2022] [Accepted: 09/14/2022] [Indexed: 11/16/2022]
Abstract
BACKGROUND Biological variation (BV) data may be used to develop analytical performance specifications (APS), reference change values (RCV), and support the applicability of population reference intervals. This study estimates within-subject BV (CVI) for several endocrine biomarkers using 3 different methodological approaches. METHODS For the direct method, 30 healthy volunteers were sampled weekly for 10 consecutive weeks. Samples were analyzed in duplicate for 17-hydroxyprogesterone (17-OHP), androstenedione, cortisol, cortisone, estradiol, follicle-stimulating hormone (FSH), luteinizing hormone (LH), sex hormone-binding globulin (SHBG), and testosterone. A CV-ANOVA with outlier removal and a Bayesian model were applied to derive the CVI. For estradiol, FSH and LH, only the male subgroup was included. In the indirect method, using the same analytes and groups, pairs of sequential results were extracted from the laboratory information system. The total result variation for individual pairs was determined by identifying a central gaussian distribution in the ratios of the result pairs. The CVI was then estimated by removing the effect of analytical variation. RESULTS The estimated CVI from the Bayesian model (μCVP(i)) in the total cohort was: 17-OHP, 23%; androstenedione, 20%; cortisol, 18%; cortisone, 11%; SHBG, 7.4%; testosterone, 16%; and for the sex hormones in men: estradiol, 14%; FSH, 8%; and LH, 26%. CVI-heterogeneity was present for most endocrine markers. Similar CVI data were estimated using the CV-ANOVA and the indirect method. CONCLUSIONS Similar CVI data were obtained using 2 different direct and one indirect method. The indirect approach is a low-cost alternative ensuring implementation of CVI data applicable for local conditions.
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Affiliation(s)
- Eirik Åsen Røys
- Department of Medical Biochemistry and Pharmacology, Haukeland University Hospital, Bergen, Norway
| | - Nora Alicia Guldhaug
- Hormone Laboratory, Department of Medical Biochemistry and Pharmacology, Haukeland University Hospital, Bergen, Norway
| | - Kristin Viste
- Hormone Laboratory, Department of Medical Biochemistry and Pharmacology, Haukeland University Hospital, Bergen, Norway
| | - Graham Dallas Jones
- Department of Chemical Pathology, SydPath, St. Vincent's Hospital, Sydney, Darlinghurst, NSW, Australia.,Faculty of Medicine, University of New South Wales, Kensington, NSW, Australia
| | - Bashir Alaour
- King's BHF Centre of Research Excellence, School of Cardiovascular Medicine and Sciences, King's College London, London, UK
| | | | - Janniche Torsvik
- Department of Medical Biochemistry and Pharmacology, Haukeland University Hospital, Bergen, Norway
| | - Ralf Kellmann
- Hormone Laboratory, Department of Medical Biochemistry and Pharmacology, Haukeland University Hospital, Bergen, Norway
| | - Heidi Strand
- Multidisciplinary Laboratory Medicine and Medical Biochemistry, Akershus University Hospital, Lørenskog, Norway
| | - Elvar Theodorsson
- Department of Clinical Chemistry, and Department of Biomedical and Clinical Sciences, Linköping University, Linköping, Sweden
| | - Michael Marber
- King's BHF Centre of Research Excellence, School of Cardiovascular Medicine and Sciences, King's College London, London, UK
| | - Torbjørn Omland
- Institute of Clinical Medicine, University of Oslo, Oslo, Norway.,Department of Cardiology, Division of Medicine, Akershus University Hospital, Lørenskog, Norway
| | - Kristin Moberg Aakre
- Hormone Laboratory, Department of Medical Biochemistry and Pharmacology, Haukeland University Hospital, Bergen, Norway.,Department of Heart Disease, Haukeland University Hospital, Bergen, Norway.,Department of Clinical Science, University of Bergen, Bergen, Norway
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Ueland GÅ, Kellmann R, Jørstad Davidsen M, Viste K, Husebye ES, Almås B, Storr HL, Sagen JV, Mellgren G, Júlíusson PB, Methlie P. Bedtime Salivary Cortisol as a Screening Test for Cushing Syndrome in Children. J Endocr Soc 2021; 5:bvab033. [PMID: 33928203 PMCID: PMC8064046 DOI: 10.1210/jendso/bvab033] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/16/2021] [Indexed: 11/19/2022] Open
Abstract
Background Diagnosing Cushing syndrome (CS) can be challenging. The 24-hour urine free cortisol (UFC) measurement is considered gold standard. This is a laborious test, dependent on correct urine collection. Late-night salivary cortisol is easier and is used as a screening test for CS in adults, but has not been validated for use in children. Objective To define liquid chromatography tandem mass spectrometry (LC-MS/MS)-based cutoff values for bedtime and morning salivary cortisol and cortisone in children, and validate the results in children with and without CS. Methods Bedtime and morning salivary samples were collected from 320 healthy children aged 4 to 16 years. Fifty-four patients from the children’s outpatient obesity clinic and 3 children with pituitary CS were used for validation. Steroid hormones were assayed by LC-MS/MS. Cutoff levels for bedtime salivary cortisol and cortisone were defined by the 97.5% percentile in healthy subjects. Results Bedtime cutoff levels for cortisol and cortisone were 2.4 and 12.0 nmol/L, respectively. Applying these cutoff levels on the verification cohort, 1 child from the obesity clinic had bedtime salivary cortisol exceeding the defined cutoff level, but normal salivary cortisone. All 3 children with pituitary CS had salivary cortisol and cortisone far above the defined bedtime cutoff levels. Healthy subjects showed a significant decrease in salivary cortisol from early morning to bedtime. Conclusions We propose that bedtime salivary cortisol measured by LC-MS/MS with a diagnostic threshold above 2.4 nmol/L can be applied as a screening test for CS in children. Age- and gender-specific cutoff levels are not needed.
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Affiliation(s)
- Grethe Å Ueland
- Hormone Laboratory, Department of Medical Biochemistry and Pharmacology, Haukeland University Hospital, 5021 Bergen, Norway.,Department of Medicine, Haukeland University Hospital, 5021 Bergen, Norway
| | - Ralf Kellmann
- Hormone Laboratory, Department of Medical Biochemistry and Pharmacology, Haukeland University Hospital, 5021 Bergen, Norway
| | - Melissa Jørstad Davidsen
- Hormone Laboratory, Department of Medical Biochemistry and Pharmacology, Haukeland University Hospital, 5021 Bergen, Norway.,Department of Clinical Science, University of Bergen, 5021 Bergen, Norway
| | - Kristin Viste
- Hormone Laboratory, Department of Medical Biochemistry and Pharmacology, Haukeland University Hospital, 5021 Bergen, Norway
| | - Eystein S Husebye
- Department of Medicine, Haukeland University Hospital, 5021 Bergen, Norway.,Department of Clinical Science, University of Bergen, 5021 Bergen, Norway.,K.G. Jebsen Center for Autoimmune Disorders, University of Bergen, 5021 Bergen, Norway
| | - Bjørg Almås
- Hormone Laboratory, Department of Medical Biochemistry and Pharmacology, Haukeland University Hospital, 5021 Bergen, Norway
| | - Helen L Storr
- K.Centre for Endocrinology, William Harvey Research Institute, Barts and the London School of Medicine & Dentistry, Queen Mary University of London, London, UK
| | - Jørn V Sagen
- Hormone Laboratory, Department of Medical Biochemistry and Pharmacology, Haukeland University Hospital, 5021 Bergen, Norway.,Department of Clinical Science, University of Bergen, 5021 Bergen, Norway
| | - Gunnar Mellgren
- Hormone Laboratory, Department of Medical Biochemistry and Pharmacology, Haukeland University Hospital, 5021 Bergen, Norway.,Department of Clinical Science, University of Bergen, 5021 Bergen, Norway.,Mohn Nutrition Research Laboratory, University of Bergen, 5021 Bergen, Norway
| | - Petur B Júlíusson
- Department of Clinical Science, University of Bergen, 5021 Bergen, Norway.,Department of Pediatrics, Haukeland University Hospital, 5021 Bergen, Norway.,Department of Health Registries, Norwegian Institute of Public Health, 5020 Bergen, Norway
| | - Paal Methlie
- Hormone Laboratory, Department of Medical Biochemistry and Pharmacology, Haukeland University Hospital, 5021 Bergen, Norway.,Department of Medicine, Haukeland University Hospital, 5021 Bergen, Norway
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Soeriyadi AH, Mazmouz R, Pickford R, Al‐Sinawi B, Kellmann R, Pearson LA, Neilan BA. Cover Feature: Heterologous Expression of an Unusual Ketosynthase, SxtA, Leads to Production of Saxitoxin Intermediates in
Escherichia coli
(5/2021). Chembiochem 2021. [DOI: 10.1002/cbic.202100062] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Angela H. Soeriyadi
- School of Biotechnology and Biomolecular Sciences University of New South Wales Kensington NSW 2052 Australia
| | - Rabia Mazmouz
- School of Biotechnology and Biomolecular Sciences University of New South Wales Kensington NSW 2052 Australia
| | - Russell Pickford
- Bioanalytical Mass Spectrometry Facility University of New South Wales Kensington NSW 2052 Australia
| | - Bakir Al‐Sinawi
- School of Biotechnology and Biomolecular Sciences University of New South Wales Kensington NSW 2052 Australia
| | - Ralf Kellmann
- Department of Biological Sciences University of Bergen Bergen 5020 Norway
| | - Leanne A. Pearson
- School of Environmental and Life Sciences University of Newcastle Callaghan NSW 2308 Australia
| | - Brett A. Neilan
- School of Environmental and Life Sciences University of Newcastle Callaghan NSW 2308 Australia
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Soeriyadi AH, Mazmouz R, Pickford R, Al-Sinawi B, Kellmann R, Pearson LA, Neilan BA. Heterologous Expression of an Unusual Ketosynthase, SxtA, Leads to Production of Saxitoxin Intermediates in Escherichia coli. Chembiochem 2020; 22:845-849. [PMID: 33084210 DOI: 10.1002/cbic.202000675] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2020] [Revised: 10/19/2020] [Indexed: 11/06/2022]
Abstract
Paralytic shellfish toxins (PSTs) are neurotoxic alkaloids produced by freshwater cyanobacteria and marine dinoflagellates. Due to their antagonism of voltage-gated sodium channels in excitable cells, certain analogues are of significant pharmacological interest. The biosynthesis of the parent compound, saxitoxin, is initiated with the formation of 4-amino-3-oxo-guanidinoheptane (ethyl ketone) by an unusual polyketide synthase-like enzyme, SxtA. We have heterologously expressed SxtA from Raphidiopsis raciborskii T3 in Escherichia coli and analysed its activity in vivo. Ethyl ketone and a truncated analogue, methyl ketone, were detected by HPLC-ESI-HRMS analysis, thus suggesting that SxtA has relaxed substrate specificity in vivo. The chemical structures of these products were further verified by tandem mass spectrometry and labelled-precursor feeding with [guanidino-15 N2 ] arginine and [1,2-13 C2 ] acetate. These results indicate that the reactions catalysed by SxtA could give rise to multiple PST variants, including analogues of ecological and pharmacological significance.
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Affiliation(s)
- Angela H Soeriyadi
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Kensington, NSW 2052, Australia
| | - Rabia Mazmouz
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Kensington, NSW 2052, Australia
| | - Russell Pickford
- Bioanalytical Mass Spectrometry Facility, University of New South Wales, Kensington, NSW 2052, Australia
| | - Bakir Al-Sinawi
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Kensington, NSW 2052, Australia
| | - Ralf Kellmann
- Department of Biological Sciences, University of Bergen, Bergen, 5020, Norway
| | - Leanne A Pearson
- School of Environmental and Life Sciences, University of Newcastle, Callaghan, NSW 2308, Australia
| | - Brett A Neilan
- School of Environmental and Life Sciences, University of Newcastle, Callaghan, NSW 2308, Australia
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Bertelsen BE, Kellmann R, Viste K, Bjørnevik AT, Eikesdal HP, Lønning PE, Sagen JV, Almås B. An Ultrasensitive Routine LC-MS/MS Method for Estradiol and Estrone in the Clinically Relevant Sub-Picomolar Range. J Endocr Soc 2020; 4:bvaa047. [PMID: 32500111 PMCID: PMC7252770 DOI: 10.1210/jendso/bvaa047] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/03/2019] [Accepted: 04/20/2020] [Indexed: 01/29/2023] Open
Abstract
BACKGROUND Current analytical routine methods lack the sensitivity to monitor plasma estrogen levels in breast cancer patients treated with aromatase inhibitors. Such monitoring is warranted for premenopausal patients treated with an aromatase inhibitor and an LH-releasing hormone analogue in particular. Therefore, we aimed to develop a routine tandem mass spectroscopy combined with liquid chromatography (LC-MS/MS) method for estradiol (E2) and estrone (E1) for use in the sub-picomolar range. METHOD Calibrators, quality controls (QC), or serum samples were spiked with isotope-labeled internal standard and purified by liquid-liquid extraction. The reconstituted extracts were analyzed by LC-MS/MS in negative electrospray ionization mode. QCs at 6 levels made from pooled patient sera were used to validate the accuracy, sensitivity, and precision of the method. RESULTS We achieved limits of quantification of 0.6 pmol/L (0.16 pg/mL) for E2 and 0.3 pmol/L (0.07 pg/mL) for E1. The coefficient of variation was below 9.0% at all QC levels for E2 (range, 1.7-153 pmol/L), and below 7.8% for E1 (range, 1.7-143 pmol/L). The method is traceable to the E2 reference standard BCR576. Reference ranges for E2 and E1 in healthy, postmenopausal women were obtained, for E2: 3.8 to 36 pmol/L, for E1: 22 to 122 pmol/L. We measured and confirmed ultra-low E2 and E1 concentrations in sera from patients on the aromatase inhibitors letrozole or exemestane. CONCLUSION This ultrasensitive LC-MS/MS method is suitable for routine assessment of serum E1 and E2 levels in breast cancer patients during estrogen suppression therapy. The method satisfies all requirements for measurement of E2 in the clinical setting as stated by the Endocrine Society in 2013. PRECIS We report an ultrasensitive LCMS/MS routine assay that measures pretreatment and suppressed levels of estradiol/estrone during aromatase inhibitor treatment of postmenopausal breast cancer patients.
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Affiliation(s)
| | - Ralf Kellmann
- Hormone Laboratory, Haukeland University Hospital, Bergen, Norway
| | - Kristin Viste
- Hormone Laboratory, Haukeland University Hospital, Bergen, Norway
| | | | - Hans Petter Eikesdal
- Department of Oncology Haukeland University Hospital, Bergen, Norway
- Department of Clinical Science, University of Bergen, Norway
| | - Per Eystein Lønning
- Department of Oncology Haukeland University Hospital, Bergen, Norway
- Department of Clinical Science, University of Bergen, Norway
| | - Jørn V Sagen
- Hormone Laboratory, Haukeland University Hospital, Bergen, Norway
- Department of Clinical Science, University of Bergen, Norway
| | - Bjørg Almås
- Hormone Laboratory, Haukeland University Hospital, Bergen, Norway
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Ahmed KEM, Frøysa HG, Karlsen OA, Blaser N, Zimmer KE, Berntsen HF, Verhaegen S, Ropstad E, Kellmann R, Goksøyr A. Effects of defined mixtures of POPs and endocrine disruptors on the steroid metabolome of the human H295R adrenocortical cell line. Chemosphere 2019; 218:328-339. [PMID: 30476764 DOI: 10.1016/j.chemosphere.2018.11.057] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/06/2018] [Revised: 11/07/2018] [Accepted: 11/08/2018] [Indexed: 06/09/2023]
Abstract
The presence of environmental pollutants in our ecosystem may impose harmful health effects to wildlife and humans. Several of these toxic chemicals have a potential to interfere with the endocrine system. The adrenal cortex has been identified as the main target organ affected by endocrine disrupting chemicals. The aim of this work was to assess exposure effects of defined and environmentally relevant mixtures of chlorinated, brominated and perfluorinated chemicals on steroidogenesis, using the H295R adrenocortical cell line model in combination with a newly developed liquid chromatography tandem mass spectrometry (LC-MS/MS) method. By using this approach, we could simultaneously analyze 19 of the steroids in the steroid biosynthesis pathway, revealing a deeper insight into possible disruption of steroidogenesis. Our results showed a noticeable down-regulation in steroid production when cells were exposed to the highest concentration of a mixture of brominated and fluorinated compounds (10,000-times human blood values). In contrast, up-regulation was observed with estrone under the same experimental condition, as well as with some other steroids when cells were exposed to a perfluorinated mixture (1000-times human blood values), and the mixture of chlorinated and fluorinated compounds. Interestingly, the low concentration of the perfluorinated mixture alone produced a significant, albeit small, down-regulation of pregnenolone, and the total mixture a similar effect on 17-hydroxypregnenolone. Other mixtures resulted in only slight deviations from the control. Indication of synergistic effects were noted when we used a statistical model to improve data interpretation. A potential for adverse outcomes of human exposures is indicated, pointing to the need for further investigation into these mixtures.
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Affiliation(s)
| | - Håvard G Frøysa
- Department of Mathematics, University of Bergen, P.O. Box 7803, N-5020 Bergen, Norway.
| | - Odd André Karlsen
- Department of Biological Sciences, University of Bergen, P.O. Box 7803, N-5020 Bergen, Norway.
| | - Nello Blaser
- Department of Mathematics, University of Bergen, P.O. Box 7803, N-5020 Bergen, Norway.
| | - Karin Elisabeth Zimmer
- Department of Basic Sciences and Aquatic Medicine, Faculty of Veterinary Medicine, Norwegian University of Life Sciences (NMBU), P.O. Box 8146 Dep. N-0033, Oslo, Norway.
| | - Hanne Friis Berntsen
- Department of Production Animal Clinical Sciences, Faculty of Veterinary Medicine, Norwegian University of Life Sciences (NMBU), P.O. Box 8146 Dep. N-0033, Oslo, Norway; Department of Administration, Lab Animal Unit, National Institute of Occupational Health, P.O. Box 5330 Majorstuen, N-0304, Oslo, Norway.
| | - Steven Verhaegen
- Department of Production Animal Clinical Sciences, Faculty of Veterinary Medicine, Norwegian University of Life Sciences (NMBU), P.O. Box 8146 Dep. N-0033, Oslo, Norway.
| | - Erik Ropstad
- Department of Production Animal Clinical Sciences, Faculty of Veterinary Medicine, Norwegian University of Life Sciences (NMBU), P.O. Box 8146 Dep. N-0033, Oslo, Norway.
| | - Ralf Kellmann
- Hormone Laboratory, Haukeland University Hospital, N-5021 Bergen, Norway.
| | - Anders Goksøyr
- Department of Biological Sciences, University of Bergen, P.O. Box 7803, N-5020 Bergen, Norway.
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Ueland GÅ, Methlie P, Øksnes M, Thordarson HB, Sagen J, Kellmann R, Mellgren G, Ræder M, Dahlqvist P, Dahl SR, Thorsby PM, Løvås K, Husebye ES. The Short Cosyntropin Test Revisited: New Normal Reference Range Using LC-MS/MS. J Clin Endocrinol Metab 2018; 103:1696-1703. [PMID: 29452421 DOI: 10.1210/jc.2017-02602] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/01/2017] [Accepted: 02/09/2018] [Indexed: 02/13/2023]
Abstract
BACKGROUND The cosyntropin test is used to diagnose adrenal insufficiency (AI) and nonclassical congenital adrenal hyperplasia (NCCAH). Current cutoffs for cortisol and 17-hydroxyprogesterone (17-OHP) are derived from nonstandardized immunoassays. Liquid chromatography tandem mass spectrometry (LC-MS/MS) offers direct measurement of steroids, prompting the need to re-establish normal ranges. OBJECTIVE The goal of this study was to define cutoff values for cortisol and 17-OHP in serum by LC-MS/MS 30 and 60 minutes after intravenous administration of 250 µg tetracosactide acetate to healthy volunteers and to compare the results with LC-MS/MS with routine immunoassays. METHODS Cosyntropin testing was performed in healthy subjects (n = 138) and in patients referred for evaluation of adrenocortical function (n = 94). Steroids were assayed by LC-MS/MS and compared with two immunoassays used in routine diagnostics (Immulite and Roche platforms). The cutoff level for cortisol was defined as the 2.5% percentile in healthy subjects not using oral estrogens (n = 121) and for 17-OHP as the 97.5% percentile. RESULTS Cortisol cutoff levels for LC-MS/MS were 412 and 485 nmol/L at 30 and 60 minutes, respectively. Applying the new cutoffs, 13 of 60 (22%) subjects who had AI according to conventional criteria now had a normal test result. For 17-OHP, the cutoff levels were 8.9 and 9.0 nmol/L at 30 and 60 minutes, respectively. CONCLUSIONS LC-MS/MS provides cutoff levels for cortisol and 17-OHP after cosyntropin stimulation that are lower than those based on immunoassays, possibly because cross-reactivity between steroid intermediates and cortisol is eliminated. This reduces the number of false-positive tests for AI and false-negative tests for NCCAH.
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Affiliation(s)
- Grethe Å Ueland
- Department of Clinical Science, University of Bergen, Bergen, Norway
- K.G. Jebsen Senter for Autoimmune Sykdommer, University of Bergen, Bergen, Norway
- Department of Medicine, Haukeland University Hospital, Bergen, Norway
| | - Paal Methlie
- Department of Clinical Science, University of Bergen, Bergen, Norway
- K.G. Jebsen Senter for Autoimmune Sykdommer, University of Bergen, Bergen, Norway
- Department of Medicine, Haukeland University Hospital, Bergen, Norway
| | - Marianne Øksnes
- Department of Clinical Science, University of Bergen, Bergen, Norway
- K.G. Jebsen Senter for Autoimmune Sykdommer, University of Bergen, Bergen, Norway
- Department of Medicine, Haukeland University Hospital, Bergen, Norway
| | | | - Jørn Sagen
- Department of Clinical Science, University of Bergen, Bergen, Norway
- Hormone Laboratory, Haukeland University Hospital, Bergen, Norway
| | - Ralf Kellmann
- Hormone Laboratory, Haukeland University Hospital, Bergen, Norway
| | - Gunnar Mellgren
- Department of Clinical Science, University of Bergen, Bergen, Norway
- Hormone Laboratory, Haukeland University Hospital, Bergen, Norway
| | | | - Per Dahlqvist
- Department of Public Health and Clinical Medicine, Umeå University, Umeå, Sweden
| | - Sandra R Dahl
- Hormone Laboratory, Department of Medical Biochemistry, Oslo University Hospital Aker, Oslo, Norway
| | - Per M Thorsby
- Hormone Laboratory, Department of Medical Biochemistry, Oslo University Hospital Aker, Oslo, Norway
| | - Kristian Løvås
- Department of Clinical Science, University of Bergen, Bergen, Norway
- K.G. Jebsen Senter for Autoimmune Sykdommer, University of Bergen, Bergen, Norway
- Department of Medicine, Haukeland University Hospital, Bergen, Norway
| | - Eystein S Husebye
- Department of Clinical Science, University of Bergen, Bergen, Norway
- K.G. Jebsen Senter for Autoimmune Sykdommer, University of Bergen, Bergen, Norway
- Department of Medicine, Haukeland University Hospital, Bergen, Norway
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Ueland GÅ, Methlie P, Kellmann R, Bjørgaas M, Åsvold BO, Thorstensen K, Kelp O, Thordarson HB, Mellgren G, Løvås K, Husebye ES. Simultaneous assay of cortisol and dexamethasone improved diagnostic accuracy of the dexamethasone suppression test. Eur J Endocrinol 2017; 176:705-713. [PMID: 28298353 DOI: 10.1530/eje-17-0078] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/30/2017] [Revised: 03/10/2017] [Accepted: 03/15/2017] [Indexed: 11/08/2022]
Abstract
OBJECTIVES The overnight dexamethasone (DXM) suppression test (DST) has high sensitivity, but moderate specificity, for diagnosing hypercortisolism. We have evaluated if simultaneous measurement of S-DXM may correct for variable DXM bioavailability and increase the diagnostic performance of DST, and if saliva (sa) is a feasible adjunct or alternative to serum. DESIGN AND METHODS Prospective study of DST was carried out in patients with suspected Cushing's syndrome (CS) (n = 49), incidentaloma (n = 152) and healthy controls (n = 101). Cortisol, cortisone and DXM were assayed by liquid chromatography-tandem mass spectrometry (LC-MS/MS). RESULTS Three hundred and two subjects underwent DST; S-cortisol was ≥50 nmol/L in 83 patients, of whom 11 had CS and 27 had autonomous cortisol secretion. The lower 2.5 percentile of S-DXM in subjects with negative DST (n = 208) was 3.3 nmol/L, which was selected as the DXM cut-off level. Nine patients had the combination of low S-DXM and positive DST. Of these, three had been misdiagnosed as having autonomous cortisol secretion. DST results were highly reproducible and confirmed in a replication cohort (n = 58). Patients with overt CS had significantly elevated post-DST sa-cortisol and sa-cortisone levels compared with controls; 23 of 25 with autonomous cortisol secretion had elevated sa-cortisone and 14 had elevated sa-cortisol. CONCLUSIONS Simultaneous measurement of serum DXM and cortisol reduced false-positive DSTs by 20% and improved the specificity. S-DXM >3.3 nmol/L is sufficient for the suppression of cortisol <50 nmol/L. Measurement of glucocorticoids in saliva is a non-invasive and easy procedure and post-DST sa-cortisone was found particularly useful in the diagnosis of CS.
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Affiliation(s)
- Grethe Å Ueland
- Department of Clinical ScienceUniversity of Bergen, Bergen, Norway
- Department of Medicine
- Department of the Hormone LaboratoryHaukeland University Hospital, Bergen, Norway
| | - Paal Methlie
- Department of Clinical ScienceUniversity of Bergen, Bergen, Norway
- Department of Medicine
| | - Ralf Kellmann
- Department of the Hormone LaboratoryHaukeland University Hospital, Bergen, Norway
| | - Marit Bjørgaas
- Department of EndocrinologySt. Olav's Hospital, Trondheim, Norway
| | - Bjørn O Åsvold
- Department of EndocrinologySt. Olav's Hospital, Trondheim, Norway
- Department of Public Health and General PracticeNorwegian University of Science and Technology, Trondheim, Norway
| | | | - Oskar Kelp
- Department of EndocrinologyAkershus University Hospital, Lørenskog, Norway
| | | | - Gunnar Mellgren
- Department of Clinical ScienceUniversity of Bergen, Bergen, Norway
- Department of the Hormone LaboratoryHaukeland University Hospital, Bergen, Norway
| | - Kristian Løvås
- Department of Clinical ScienceUniversity of Bergen, Bergen, Norway
- Department of Medicine
| | - Eystein S Husebye
- Department of Clinical ScienceUniversity of Bergen, Bergen, Norway
- Department of Medicine
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Braadland PR, Grytli HH, Ramberg H, Katz B, Gauthier-Landry L, Kellmann R, Krobert KA, Wang W, Svindland A, Levy FO, Berge V, Mellgren G, Barbier O, Taskén KA. Abstract A01: ADRB2 regulates phase II steroid metabolism and determines development of castration-resistant prostate cancer. Mol Cancer Res 2016. [DOI: 10.1158/1557-3125.metca15-a01] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Abstract
The underlying mechanisms responsible for the development of castration-resistant prostate cancer (CRPC) are not fully understood. The β2-adrenergic receptor (ADRB2) is a key regulator of a wide range of metabolic processes in the body, and it has been implicated in androgen receptor signaling and development of CRPC. We have unpublished data which shows that low expression of ADRB2 predicts a more rapid development of CRPC. Based on this finding, we wanted to investigate whether the ADRB2 level/activity impacts cellular features to help explain how and why the receptor has prognostic value in prostate cancer.
We stably transfected androgen-dependent LNCaP cells with shRNAs to mimic the clinical situation where patients have differential levels of ADRB2 in their prostate epithelial carcinomas. Gene expression profiling revealed changes in expression of several metabolic genes. Among the most regulated were two androgen-glucuronidating UDP-glucuronosyltransferase 2B (UGT2B) enzymes, UGT2B15 and UGT2B17. Both enzymes are critical in the phase-II metabolic pathway responsible for elimination of androgens by glucuronidation in the prostate, and they were highly down-regulated at the mRNA level in two LNCaP cell sublines expressing low levels of ADRB2 (shADRB2). By mixing androgen substrates with protein lysates from the cell and measuring glucuronide formation by LC-MS/MS, we found that glucuronide formation mirrored the UGT2B15/2B17 expression levels. To further complement these findings, we measured androgen levels in the cells by LC-MS, and found higher levels of bioactive testosterone. As this theoretically should invoke a change in androgen receptor activity of the cells, we measured androgen regulated luciferase activities as well as prostate-specific antigen (PSA/KLK3)-expression and secretion upon stimulation with the glucuronidable androgen dihydrotestosterone. The experiments revealed a noticeable increase in androgen responsiveness in cells with low levels of ADRB2 compared to cells with normal levels of ADRB2. Upon supplementation with the synthetic, non-glucuronidable androgen R1881, no induction in androgen responsiveness was observed in the shADRB2 cells compared to control cells. Dihydrotestosterone responsiveness was inhibited upon supplementation of diclofenac sodium, an inhibitor of UDP-glucuronosyltransferase actvity, and also upon rescue of ADRB2 expression level. Finally, using immunohistochemistry with an anti-UGT2B17 antibody, we found that patients showing strong cytoplasmic UGT2B17 immunostaining intensity progressed more rapidly to CRPC.
Altering metabolic pathways, such as the steroid catabolic pathways, may be a powerful adaptive tool for cells to increase survival in an androgen-deprived micromilieu, and thus also a potential drug target. As LNCaP cells with low levels of ADRB2 display lowered glucuronidation activity, higher androgen responsiveness, and higher testosterone levels, we propose that this may be a novel metabolic mechanism by which ADRB2 affects the survival of androgen-dependent cells during androgen-deprivation therapy, and thereby development of CRPC.
Citation Format: Peder Rustøen Braadland, Helene Hartvedt Grytli, Håkon Ramberg, Betina Katz, Lois Gauthier-Landry, Ralf Kellmann, Kurt Allen Krobert, Wanzhong Wang, Aud Svindland, Finn Olav Levy, Viktor Berge, Gunnar Mellgren, Olivier Barbier, Kristin Austlid Taskén. ADRB2 regulates phase II steroid metabolism and determines development of castration-resistant prostate cancer. [abstract]. In: Proceedings of the AACR Special Conference: Metabolism and Cancer; Jun 7-10, 2015; Bellevue, WA. Philadelphia (PA): AACR; Mol Cancer Res 2016;14(1_Suppl):Abstract nr A01.
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Affiliation(s)
| | | | | | - Betina Katz
- 1Oslo University Hospital, Oslo, NA, Norway,
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10
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Murray SA, Wiese M, Stüken A, Brett S, Kellmann R, Hallegraeff G, Neilan BA. sxtA-based quantitative molecular assay to identify saxitoxin-producing harmful algal blooms in marine waters. Appl Environ Microbiol 2011; 77:7050-7. [PMID: 21841034 PMCID: PMC3187097 DOI: 10.1128/aem.05308-11] [Citation(s) in RCA: 88] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2011] [Accepted: 07/29/2011] [Indexed: 11/20/2022] Open
Abstract
The recent identification of genes involved in the production of the potent neurotoxin and keystone metabolite saxitoxin (STX) in marine eukaryotic phytoplankton has allowed us for the first time to develop molecular genetic methods to investigate the chemical ecology of harmful algal blooms in situ. We present a novel method for detecting and quantifying the potential for STX production in marine environmental samples. Our assay detects a domain of the gene sxtA that encodes a unique enzyme putatively involved in the sxt pathway in marine dinoflagellates, sxtA4. A product of the correct size was recovered from nine strains of four species of STX-producing Alexandrium and Gymnodinium catenatum and was not detected in the non-STX-producing Alexandrium species, other dinoflagellate cultures, or an environmental sample that did not contain known STX-producing species. However, sxtA4 was also detected in the non-STX-producing strain of Alexandrium tamarense, Tasmanian ribotype. We investigated the copy number of sxtA4 in three strains of Alexandrium catenella and found it to be relatively constant among strains. Using our novel method, we detected and quantified sxtA4 in three environmental blooms of Alexandrium catenella that led to STX uptake in oysters. We conclude that this method shows promise as an accurate, fast, and cost-effective means of quantifying the potential for STX production in marine samples and will be useful for biological oceanographic research and harmful algal bloom monitoring.
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Affiliation(s)
- Shauna A Murray
- Sydney Institute of Marine Sciences, Chowder Bay Road, Mosman, NSW 2088, Australia.
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Stüken A, Orr RJS, Kellmann R, Murray SA, Neilan BA, Jakobsen KS. Discovery of nuclear-encoded genes for the neurotoxin saxitoxin in dinoflagellates. PLoS One 2011; 6:e20096. [PMID: 21625593 PMCID: PMC3097229 DOI: 10.1371/journal.pone.0020096] [Citation(s) in RCA: 153] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2011] [Accepted: 04/12/2011] [Indexed: 11/26/2022] Open
Abstract
Saxitoxin is a potent neurotoxin that occurs in aquatic environments worldwide.
Ingestion of vector species can lead to paralytic shellfish poisoning, a severe
human illness that may lead to paralysis and death. In freshwaters, the toxin is
produced by prokaryotic cyanobacteria; in marine waters, it is associated with
eukaryotic dinoflagellates. However, several studies suggest that saxitoxin is
not produced by dinoflagellates themselves, but by co-cultured bacteria. Here,
we show that genes required for saxitoxin synthesis are encoded in the nuclear
genomes of dinoflagellates. We sequenced >1.2×106 mRNA
transcripts from the two saxitoxin-producing dinoflagellate strains
Alexandrium fundyense CCMP1719 and A.
minutum CCMP113 using high-throughput sequencing technology. In
addition, we used in silico transcriptome analyses, RACE, qPCR
and conventional PCR coupled with Sanger sequencing. These approaches
successfully identified genes required for saxitoxin-synthesis in the two
transcriptomes. We focused on sxtA, the unique starting gene of
saxitoxin synthesis, and show that the dinoflagellate transcripts of
sxtA have the same domain structure as the cyanobacterial
sxtA genes. But, in contrast to the bacterial homologs, the
dinoflagellate transcripts are monocistronic, have a higher GC content, occur in
multiple copies, contain typical dinoflagellate spliced-leader sequences and
eukaryotic polyA-tails. Further, we investigated 28 saxitoxin-producing and
non-producing dinoflagellate strains from six different genera for the presence
of genomic sxtA homologs. Our results show very good agreement
between the presence of sxtA and saxitoxin-synthesis, except in
three strains of A. tamarense, for which we amplified
sxtA, but did not detect the toxin. Our work opens for
possibilities to develop molecular tools to detect saxitoxin-producing
dinoflagellates in the environment.
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Affiliation(s)
- Anke Stüken
- Microbial Evolution Research Group (MERG), Department of Biology,
University of Oslo, Oslo, Norway
| | - Russell J. S. Orr
- Microbial Evolution Research Group (MERG), Department of Biology,
University of Oslo, Oslo, Norway
| | - Ralf Kellmann
- Department of Molecular Biology, University of Bergen, Bergen,
Norway
| | - Shauna A. Murray
- School of Biotechnology and Biomolecular Sciences and Australian Centre
for Astrobiology, University of New South Wales, Sydney, Australia
- Sydney Institute of Marine Sciences, Mosman, New South Wales,
Australia
| | - Brett A. Neilan
- School of Biotechnology and Biomolecular Sciences and Australian Centre
for Astrobiology, University of New South Wales, Sydney, Australia
- Sydney Institute of Marine Sciences, Mosman, New South Wales,
Australia
| | - Kjetill S. Jakobsen
- Microbial Evolution Research Group (MERG), Department of Biology,
University of Oslo, Oslo, Norway
- Department of Biology, Centre for Ecological and Evolutionary Synthesis
(CEES), University of Oslo, Oslo, Norway
- * E-mail:
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Pearson L, Mihali T, Moffitt M, Kellmann R, Neilan B. On the chemistry, toxicology and genetics of the cyanobacterial toxins, microcystin, nodularin, saxitoxin and cylindrospermopsin. Mar Drugs 2010; 8:1650-80. [PMID: 20559491 PMCID: PMC2885083 DOI: 10.3390/md8051650] [Citation(s) in RCA: 393] [Impact Index Per Article: 28.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2010] [Revised: 05/02/2010] [Accepted: 05/06/2010] [Indexed: 11/16/2022] Open
Abstract
The cyanobacteria or "blue-green algae", as they are commonly termed, comprise a diverse group of oxygenic photosynthetic bacteria that inhabit a wide range of aquatic and terrestrial environments, and display incredible morphological diversity. Many aquatic, bloom-forming species of cyanobacteria are capable of producing biologically active secondary metabolites, which are highly toxic to humans and other animals. From a toxicological viewpoint, the cyanotoxins span four major classes: the neurotoxins, hepatotoxins, cytotoxins, and dermatoxins (irritant toxins). However, structurally they are quite diverse. Over the past decade, the biosynthesis pathways of the four major cyanotoxins: microcystin, nodularin, saxitoxin and cylindrospermopsin, have been genetically and biochemically elucidated. This review provides an overview of these biosynthesis pathways and additionally summarizes the chemistry and toxicology of these remarkable secondary metabolites.
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Affiliation(s)
- Leanne Pearson
- School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sydney, NSW, 2052, Australia; E-Mails:
(L.P.);
(T.M.)
| | - Troco Mihali
- School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sydney, NSW, 2052, Australia; E-Mails:
(L.P.);
(T.M.)
| | - Michelle Moffitt
- School of Biomedical and Health Sciences, The University of Western Sydney, Campbelltown, NSW, 2560, Australia; E-Mail:
(M.M.)
| | - Ralf Kellmann
- Department of Molecular Biology, The University of Bergen, P.O. Box 7803, 5020 Bergen, Norway; E-Mail:
(R.K.)
| | - Brett Neilan
- School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sydney, NSW, 2052, Australia; E-Mails:
(L.P.);
(T.M.)
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Kellmann R, Stüken A, Orr RJS, Svendsen HM, Jakobsen KS. Biosynthesis and molecular genetics of polyketides in marine dinoflagellates. Mar Drugs 2010; 8:1011-48. [PMID: 20479965 PMCID: PMC2866473 DOI: 10.3390/md8041011] [Citation(s) in RCA: 82] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2010] [Revised: 03/17/2010] [Accepted: 03/26/2010] [Indexed: 11/20/2022] Open
Abstract
Marine dinoflagellates are the single most important group of algae that produce toxins, which have a global impact on human activities. The toxins are chemically diverse, and include macrolides, cyclic polyethers, spirolides and purine alkaloids. Whereas there is a multitude of studies describing the pharmacology of these toxins, there is limited or no knowledge regarding the biochemistry and molecular genetics involved in their biosynthesis. Recently, however, exciting advances have been made. Expressed sequence tag sequencing studies have revealed important insights into the transcriptomes of dinoflagellates, whereas other studies have implicated polyketide synthase genes in the biosynthesis of cyclic polyether toxins, and the molecular genetic basis for the biosynthesis of paralytic shellfish toxins has been elucidated in cyanobacteria. This review summarises the recent progress that has been made regarding the unusual genomes of dinoflagellates, the biosynthesis and molecular genetics of dinoflagellate toxins. In addition, the evolution of these metabolic pathways will be discussed, and an outlook for future research and possible applications is provided.
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Affiliation(s)
- Ralf Kellmann
- University of Bergen, Department of Molecular Biology, 5020 Bergen, Norway; E-Mail:
- *Author to whom correspondence should be addressed; E-Mail:
; Tel.: +47-5558-4556; Fax: +47-5558-9683
| | - Anke Stüken
- University of Oslo, Department of Biology, Centre for Ecological and Evolutionary Synthesis (CEES), 0316 Oslo, Norway; E-Mails:
(A.S.);
(K.S.J.)
- University of Oslo, Department of Biology, Microbial Evolution Research Group (MERG), 0316 Oslo, Norway; E-Mail:
| | - Russell J. S. Orr
- University of Oslo, Department of Biology, Microbial Evolution Research Group (MERG), 0316 Oslo, Norway; E-Mail:
| | - Helene M. Svendsen
- University of Bergen, Department of Molecular Biology, 5020 Bergen, Norway; E-Mail:
| | - Kjetill S. Jakobsen
- University of Oslo, Department of Biology, Centre for Ecological and Evolutionary Synthesis (CEES), 0316 Oslo, Norway; E-Mails:
(A.S.);
(K.S.J.)
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Kellmann R, Schaffner CA, Grønset TA, Satake M, Ziegler M, Fladmark KE. Proteomic response of human neuroblastoma cells to azaspiracid-1. J Proteomics 2009; 72:695-707. [DOI: 10.1016/j.jprot.2009.02.008] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2008] [Revised: 02/11/2009] [Accepted: 02/16/2009] [Indexed: 12/25/2022]
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Mihali TK, Kellmann R, Neilan BA. Characterisation of the paralytic shellfish toxin biosynthesis gene clusters in Anabaena circinalis AWQC131C and Aphanizomenon sp. NH-5. BMC Biochem 2009; 10:8. [PMID: 19331657 PMCID: PMC2679770 DOI: 10.1186/1471-2091-10-8] [Citation(s) in RCA: 126] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/14/2008] [Accepted: 03/30/2009] [Indexed: 11/10/2022]
Abstract
BACKGROUND Saxitoxin and its analogues collectively known as the paralytic shellfish toxins (PSTs) are neurotoxic alkaloids and are the cause of the syndrome named paralytic shellfish poisoning. PSTs are produced by a unique biosynthetic pathway, which involves reactions that are rare in microbial metabolic pathways. Nevertheless, distantly related organisms such as dinoflagellates and cyanobacteria appear to produce these toxins using the same pathway. Hypothesised explanations for such an unusual phylogenetic distribution of this shared uncommon metabolic pathway, include a polyphyletic origin, an involvement of symbiotic bacteria, and horizontal gene transfer. RESULTS We describe the identification, annotation and bioinformatic characterisation of the putative paralytic shellfish toxin biosynthesis clusters in an Australian isolate of Anabaena circinalis and an American isolate of Aphanizomenon sp., both members of the Nostocales. These putative PST gene clusters span approximately 28 kb and contain genes coding for the biosynthesis and export of the toxin. A putative insertion/excision site in the Australian Anabaena circinalis AWQC131C was identified, and the organization and evolution of the gene clusters are discussed. A biosynthetic pathway leading to the formation of saxitoxin and its analogues in these organisms is proposed. CONCLUSION The PST biosynthesis gene cluster presents a mosaic structure, whereby genes have apparently transposed in segments of varying size, resulting in different gene arrangements in all three sxt clusters sequenced so far. The gene cluster organizational structure and sequence similarity seems to reflect the phylogeny of the producer organisms, indicating that the gene clusters have an ancient origin, or that their lateral transfer was also an ancient event. The knowledge we gain from the characterisation of the PST biosynthesis gene clusters, including the identity and sequence of the genes involved in the biosynthesis, may also afford the identification of these gene clusters in dinoflagellates, the cause of human mortalities and significant financial loss to the tourism and shellfish industries.
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Affiliation(s)
- Troco K Mihali
- School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sydney, NSW 2052, Australia
| | - Ralf Kellmann
- Department of Molecular Biology, University of Bergen, P.O. Box 7803, 5020 Bergen, Norway
| | - Brett A Neilan
- School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sydney, NSW 2052, Australia
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Kellmann R, Mihali TK, Michali TK, Neilan BA, Neilan BA. Identification of a saxitoxin biosynthesis gene with a history of frequent horizontal gene transfers. J Mol Evol 2008; 67:526-38. [PMID: 18850059 DOI: 10.1007/s00239-008-9169-2] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2008] [Revised: 07/04/2008] [Accepted: 09/22/2008] [Indexed: 11/24/2022]
Abstract
The paralytic shellfish poisoning (PSP) toxins, saxitoxin, and its derivatives, are produced by a complex and unique biosynthetic pathway. It involves reactions that are rare in other metabolic pathways, however, distantly related organisms, such as dinoflagellates and cyanobacteria, produce these toxins by an identical pathway. Speculative explanations for the unusual phylogenetic distribution of this metabolic pathway have been proposed, including a polyphyletic origin, the involvement of symbiotic bacteria, and horizontal gene transfer. This study describes for the first time the identity of one gene, sxt1, that is involved in the biosynthesis of saxitoxin in cyanobacteria. It encoded an O-carbamoyltransferase (OCTASE) that was proposed to carbamoylate the hydroxymethyl side chain of saxitoxin precursor. Orthologues of sxt1 were exclusively present in PSP-toxic strains of cyanobacteria and had a high sequence similarity to each other. L. wollei had a naturally mutated sxt1 gene that encoded an inactive enzyme, and was incapable of producing carbamoylated PSP-toxin analogues, supporting the proposed function of Sxt1. Phylogenetic analysis revealed that OCATSE genes were present exclusively in prokaryotic organisms and were characterized by a high rate of horizontal gene transfer. OCTASE has most likely evolved from an ancestral O-sialoglycoprotein endopeptidase from proteobacteria, whereas the most likely phylogenetic origin of sxt1 was an ancestral alpha-proteobacterium. The phylogeny of sxt1 suggested that the entire set of genes required for saxitoxin biosynthesis may spread by horizontal gene transfer.
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Affiliation(s)
- Ralf Kellmann
- Department of Molecular Biology, University of Bergen, P.O. Box 7803, 5020, Bergen, Norway.
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Pomati F, Kellmann R, Cavalieri R, Burns BP, Neilan BA. Comparative gene expression of PSP-toxin producing and non-toxic Anabaena circinalis strains. Environ Int 2006; 32:743-8. [PMID: 16650472 DOI: 10.1016/j.envint.2006.03.010] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/16/2005] [Revised: 03/08/2006] [Accepted: 03/14/2006] [Indexed: 05/08/2023]
Abstract
Blooms of the freshwater cyanobacterium Anabaena circinalis are recognised as an important health risk worldwide due to the production of a range of toxins such as saxitoxin (STX) and its derivatives, also known as paralytic shellfish poisoning (PSP) toxins. In this study the transcriptional profile of PSP toxin-producing and non-toxic strains of A. circinalis was investigated by means of a DNA microarray approach. Additionally, gene expression was studied after exposure of toxic A. circinalis cultures to lidocaine hydrochloride at 1 microM for 2 h. Under standard growth conditions, a limited number of putative toxic-strain distinctive DNA fragments, identified in previous studies, were preferentially expressed in toxic versus non-toxic strains. The same genes did not significantly change their expression after exposure to 1 microM lidocaine, conditions previously shown to induce STX production in the cyanobacterium Cylindrospermopsis raciborskii T3. Lidocaine supplementation, however, enhanced the transcription of genes involved in physiological adaptive responses and bloom formation in cyanobacteria, such as the gas vesicle structural protein A and phycocyanin. The heat shock protein HSP-70 and the chlorophyll-a binding protein isiA were significantly repressed by lidocaine exposure. Stress response proteins and genes implicated in secondary metabolism were repressed, including phosphopantetheinyl transferases. The BGGM1 DNA microarray, used in this study, was shown to be suitable for gene expression studies in cultured toxic cyanobacteria and allowed the analysis of gene transcripts associated with surface scum formation by toxic A. circinalis.
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Affiliation(s)
- Francesco Pomati
- Cyanobacteria and Astrobiology Research Laboratory, School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney 2052, NSW, Australia
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Kellmann R, Mills T, Neilan BA. Functional Modeling and Phylogenetic Distribution of Putative Cylindrospermopsin Biosynthesis Enzymes. J Mol Evol 2006; 62:267-80. [PMID: 16508696 DOI: 10.1007/s00239-005-0030-6] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2005] [Accepted: 06/14/2005] [Indexed: 10/25/2022]
Abstract
The alkaloid cylindrospermopsin is the most recently discovered cyanotoxin and has caused epidemic outbreaks of human poisoning. Cylindrospermopsin producing cyanobacteria have in recent times appeared in countries all over the world where they had not been observed previously and, thus, represent a global public health concern. Three putative cylindrospermopsin biosynthesis genes, encoding an amidinotransferase (aoaA), a nonribosomal peptide synthetase (aoaB), and a polyketide synthase (aoaC), have been described. Most cyanotoxins are the product of nonribosomal peptide and polyketide synthesis, but the involvement of an amidinotransferase is novel. In the present study, functional modeling was carried out to gain insight into the mechanism of precursor recruitment in cylindrospermopsin biosynthesis. In addition, the molecular phylogenies of putative cylindrospermopsin biosynthesis genes and producer organisms were determined. The model indicated that AoaA may catalyze the formation of guanidino acetate from glycine and arginine. The catalytic site of the AoaB adenylation domain provided two aspartate residues, instead of the usual one, which may be involved in the binding of the guanidino moiety of guanidino acetate. Molecular phylogenetic analysis grouped cylindrospermopsin producing cyanobacteria into two divergent groups. Although the phylogeny of the cylindrospermopsin biosynthesis genes followed that of the producer organisms, they were less divergent, which may indicate the recent horizontal transfer of these genes.
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Affiliation(s)
- Ralf Kellmann
- School of Biotechnology and Biomolecular Sciences, Section Microbiology, The University of New South Wales, Biotechnology, Sydney, Australia
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