| 1. |
- Wilman, H. R., et al.
(författare)
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Genetic studies of abdominal MRI data identify genes regulating hepcidin as major determinants of liver iron concentration
- 2019
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Ingår i: Journal of Hepatology. - : Elsevier. - 0168-8278 .- 1600-0641. ; 71:3, s. 594-602
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Tidskriftsartikel (refereegranskat)abstract
- Background & Aims: Excess liver iron content is common and is linked to the risk of hepatic and extrahepatic diseases. We aimed to identify genetic variants influencing liver iron content and use genetics to understand its link to other traits and diseases. Methods: First, we performed a genome-wide association study (GWAS) in 8,289 individuals from UK Biobank, whose liver iron level had been quantified by magnetic resonance imaging, before validating our findings in an independent cohort (n = 1,513 from IMI DIRECT). Second, we used Mendelian randomisation to test the causal effects of 25 predominantly metabolic traits on liver iron content. Third, we tested phenome-wide associations between liver iron variants and 770 traits and disease outcomes. Results: We identified 3 independent genetic variants (rs1800562 [C282Y] and rs1799945 [H63D] in HFE and rs855791 [V736A] in TMPRSS6) associated with liver iron content that reached the GWAS significance threshold (p <5 × 10−8). The 2 HFE variants account for ∼85% of all cases of hereditary haemochromatosis. Mendelian randomisation analysis provided evidence that higher central obesity plays a causal role in increased liver iron content. Phenome-wide association analysis demonstrated shared aetiopathogenic mechanisms for elevated liver iron, high blood pressure, cirrhosis, malignancies, neuropsychiatric and rheumatological conditions, while also highlighting inverse associations with anaemias, lipidaemias and ischaemic heart disease. Conclusion: Our study provides genetic evidence that mechanisms underlying higher liver iron content are likely systemic rather than organ specific, that higher central obesity is causally associated with higher liver iron, and that liver iron shares common aetiology with multiple metabolic and non-metabolic diseases. Lay summary: Excess liver iron content is common and is associated with liver diseases and metabolic diseases including diabetes, high blood pressure, and heart disease. We identified 3 genetic variants that are linked to an increased risk of developing higher liver iron content. We show that the same genetic variants are linked to higher risk of many diseases, but they may also be associated with some health advantages. Finally, we use genetic variants associated with waist-to-hip ratio as a tool to show that central obesity is causally associated with increased liver iron content.
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| 2. |
- Orejas, C, et al.
(författare)
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Cold-water corals in aquaria: advances and challenges. A focus on the Mediterranean
- 2019
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Ingår i: Mediterranean Cold-Water Corals: Past, Present and Future. - : Springer. - 2213-719X. - 9783319916071
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Bokkapitel (refereegranskat)abstract
- Knowledge on basic biological functions of organisms is essential to understand not only the role they play in the ecosystems but also to manage and protect their populations. The study of biological processes, such as growth, reproduction and physiology, which can be approached in situ or by collecting exemplars and rearing them in aquaria, is particularly challenging for deep-sea organisms such as cold-water corals (CWCs). Present experimental work and monitoring of deep-sea populations is still a chimera. Only a handful of research institutes or companies have been able to install in situ marine observatories in the Mediterranean Sea or elsewhere, which facilitate for a continuous monitoring of deep-sea ecosystems. Hence, today’s best way to obtain basic biological information on these organisms is (1) working with collected samples and analysing them post-mortem and / or (2) cultivating corals in aquaria in order to monitor biological processes and investigate coral behaviour and physiological responses under different experimental treatments. The first challenging aspect is the collection process, which implies the use of oceanographic research vessels in most occasions, since these organisms inhabit areas between ca. 150 m to more than 1,000 m depth, and specific sampling gears. The next challenge is the maintenance of the animals on board (in situations where cruises may take weeks) and their transport to home laboratories. Maintenance in the home labs is also extremely challenging since special conditions and set ups are needed to conduct experimental studies to obtain information on the biological processes of these animals. The complexity of the natural environment from which the corals were collected cannot be exactly replicated within the laboratory setting; a fact which has led some researchers to question the validity of work and conclusions drawn from such undertakings. It is evident that aquaria experiments cannot perfectly reflect the real environmental and trophic conditions where these organisms occur, but: (1) in most cases we do not have the possibility to obtain equivalent in situ information and (2) even with limitations, they produce relevant information about 117 the biological limits of the species, which is especially valuable when considering potential future climate change scenarios. This chapter includes many contributions from different authors and it intends to be both, a practical “handbook” for conducting CWC aquaria work, while at the same time, to offer an overview on the CWC research conducted in Mediterranean labs equipped with aquaria infrastructure. Experiences from Atlantic and Pacific laboratories with extensive experience with CWC work have also contributed to this chapter, as their procedures are valuable to any researcher interested in conducting experimental work with CWC in aquaria. It was impossible to include contributions from all labs in the world currently working experimentally with CWCs in the laboratory, but at the conclusion of the chapter we attempt, to our best of our knowledge, to supply a list of laboratories with operational CWC aquaria facilities.
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| 3. |
- De Clippele, L. H., et al.
(författare)
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The effect of local hydrodynamics on the spatial extent and morphology of cold-water coral habitats at Tisler Reef, Norway
- 2018
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Ingår i: Coral Reefs. - : Springer Science and Business Media LLC. - 0722-4028 .- 1432-0975. ; 37:1, s. 253-266
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Tidskriftsartikel (refereegranskat)abstract
- This study demonstrates how cold-water coral morphology and habitat distribution are shaped by local hydrodynamics, using high-definition video from Tisler Reef, an inshore reef in Norway. A total of 334 video frames collected on the north-west (NW) and south-east (SE) side of the reef were investigated for Lophelia pertusa coral cover and morphology and for the cover of the associated sponges Mycale lingua and Geodia sp. Our results showed that the SE side was a better habitat for L. pertusa (including live and dead colonies). Low cover of Geodia sp. was found on both sides of Tisler Reef. In contrast, Mycale lingua had higher percentage cover, especially on the NW side of the reef. Bush-shaped colonies of L. pertusa with elongated branches were the most abundant coral morphology on Tisler Reef. The highest abundance and density of this morphology were found on the SE side of the reef, while a higher proportion of cauliflower-shaped corals with short branches were found on the NW side. The proportion of very small L. pertusa colonies was also significantly higher on the SE side of the reef. The patterns in coral spatial distribution and morphology were related to local hydrodynamics-there were more frequent periods of downwelling currents on the SE side-and to the availability of suitable settling substrates. These factors make the SE region of Tisler Reef more suitable for coral growth. Understanding the impact of local hydrodynamics on the spatial extent and morphology of coral, and their relation to associated organisms such as sponges, is key to understanding the past and future development of the reef.
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| 4. |
- Hennige, S. J., et al.
(författare)
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The potential for coral reef establishment through free-living stabilization
- 2017
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Ingår i: Scientific Reports. - : Nature Publishing Group. - 2045-2322. ; 7
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Tidskriftsartikel (refereegranskat)abstract
- Corals thrive in a variety of environments, from low wave and tidal energy lagoons, to high energy tidal reef flats, but remain dependent upon suitable substrate. Herein we reviewed the phenomenon of free-living corals (coralliths), examined whether they have the capacity to create their own stable habitat in otherwise uninhabitable, poor substrate environments through 'free-living stabilization', and explore their potential ecological role on coral reefs. This stabilization could be achieved by coral settlement and survival on mobile substrate, with subsequent growth into free-living coralliths until a critical mass is reached that prevents further movement. This allows for secondary reef colonization by other coral species. To preliminarily test this hypothesis we provide evidence that the potential to support secondary coral colonisation increases with corallith size. Due to the limited diversity of corallith species observed here and in the literature, and the lack of physiological differences exhibited by coralliths here to static controls, it seems likely that only a small selection of coral species have the ability to form coralliths, and the potential to create their own stable habitat.
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| 5. |
- Hennige, S. J., et al.
(författare)
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Hidden impacts of ocean acidification to live and dead coral framework
- 2015
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Ingår i: Proceedings of the Royal Society of London. Biological Sciences. - : Royal Society Publishing. - 0962-8452 .- 1471-2954. ; 282:1813
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Tidskriftsartikel (refereegranskat)abstract
- Cold-water corals, such as Lophelia pertusa, are key habitat-forming organisms found throughout the world's oceans to 3000 m deep. The complex three-dimensional framework made by these vulnerable marine ecosystems support high biodiversity and commercially important species. Given their importance, a key question is how both the living and the dead framework will fare under projected climate change. Here, we demonstrate that over 12 months L. pertusa can physiologically acclimate to increased CO2, showing sustained net calcification. However, their new skeletal structure changes and exhibits decreased crystallographic and molecular-scale bonding organization. Although physiological acclimatization was evident, we also demonstrate that there is a negative correlation between increasing CO2 levels and breaking strength of exposed framework (approx. 20-30% weaker after 12 months), meaning the exposed bases of reefs will be less effective load-bearers', and will become more susceptible to bioerosion and mechanical damage by 2100.
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| 6. |
- Kamenos, Nicholas A., et al.
(författare)
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Reconstructing Four Centuries of Temperature-Induced Coral Bleaching on the Great Barrier Reef
- 2018
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Ingår i: Frontiers in Marine Science. - : Frontiers Media S.A.. - 2296-7745. ; 5
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Tidskriftsartikel (refereegranskat)abstract
- Mass coral bleaching events during the last 20 years have caused major concern over the future of coral reefs worldwide. Despite damage to key ecosystem engineers, little is known about bleaching frequency prior to 1979 when regular modern systematic scientific observations began on the Great Barrier Reef (GBR). To understand the longer-term relevance of current bleaching trajectories, the likelihood of future coral acclimatization and adaptation, and thus persistence of corals, records, and drivers of natural pre-industrial bleaching frequency and prevalence are needed. Here, we use linear extensions from 44 overlapping GBR coral cores to extend the observational bleaching record by reconstructing temperature-induced bleaching patterns over 381 years spanning 1620-2001. Porites spp. corals exhibited variable bleaching patterns with bleaching frequency (number of bleaching years per decade) increasing (1620-1753), decreasing (1754-1820), and increasing (1821-2001) again. Bleaching prevalence (the proportion of cores exhibiting bleaching) fell (1670-1774) before increasing by 10% since the late 1790s concurrent with positive temperature anomalies, placing recently observed increases in GBR coral bleaching into a wider context. Spatial inconsistency along with historically diverging patterns of bleaching frequency and prevalence provide queries over the capacity for holobiont (the coral host, the symbiotic microalgae and associated microorganisms) acclimatization and adaptation via bleaching, but reconstructed increases in bleaching frequency and prevalence, may suggest coral populations are reaching an upper bleaching threshold, a "tipping point" beyond which coral survival is uncertain.
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