Publications

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8 Publications visible to you, out of a total of 8

Abstract (Expand)

Factors affecting the establishment of the gut microbiota in animals living in marine environments remain largely unknown. In terrestrial animals, however, it is well established that the juvenile environment has a major impact on the gut microbiota later in life. Atlantic salmon Salmo salar is an anadromous fish important in aquaculture with a juvenile freshwater stage and an adult seawater stage. For wild salmon, there are major dietary changes with respect to availability of long-chain polyunsaturated n-3 fatty acids (LC-n-3 PUFA) with lower abundance in freshwater systems. The aim of our work was therefore to determine the effect of a juvenile freshwater diet with high LC-n-3 PUFA, as compared to a diet low in LC-n-3 PUFA (designed to increase the endogenous LC-n-3 PUFA production), on the transition to a seawater gut microbiota for Atlantic salmon. We found a juvenile freshwater microbiota high in Firmicutes for fish raised with low LC-n-3 PUFA, while the microbiota for fish given high LC-n-3 PUFA feed was high in Proteobacteria. One hundred days after transfer to a common sea cage, fish that were given low LC-n-3 PUFA diets in freshwater showed significantly higher (p = 0.02, Kruskal-Wallis) Mycoplasma content (90 ± 7%; mean ± SD) compared to fish raised on a high LC-n-3 PUFA diet in freshwater (25 ± 31% Mycoplasma). Shotgun metagenome sequencing from fish raised with a low LC-n-3 PUFA diet identified a salmon-associated Mycoplasma in sea, being distinct from currently known Mycoplasma. The genome sequence information indicated a mutualistic lifestyle of this bacterium. Mycoplasma has also previously been identified as dominant (>70%) in sea-living adult Atlantic salmon. Taken together, our results suggest that the juvenile freshwater diet influences the establishment of the gut microbiota in marine Atlantic salmon.

Authors: Y Jin, IL Angell, SR Sandve, LG Snipen, Y Olsen, K Rudi

Date Published: 24th Jan 2019

Publication Type: Not specified

Abstract (Expand)

Gut microbiota associations through habitat transitions are fundamentally important yet poorly understood. One such habitat transition is the migration from freshwater to saltwater for anadromous fish, such as salmon. The aim of the current work was therefore to determine the freshwater-to-saltwater transition impact on the gut microbiota in farmed Atlantic salmon, with dietary interventions resembling freshwater and saltwater diets with respect to fatty acid composition. Using deep 16S rRNA gene sequencing and quantitative PCR, we found that the freshwater-to-saltwater transition had a major association with the microbiota composition and quantity, while diet did not show significant associations with the microbiota. In saltwater there was a 100-fold increase in bacterial quantity, with a relative increase of Firmicutes and a relative decrease of both Actinobacteria and Proteobacteria. Irrespective of an overall shift in microbiota composition from freshwater to saltwater, we identified three core clostridia and one Lactobacillus-affiliated phylotype with wide geographic distribution that were highly prevalent and co-occurring. Taken together, our results support the importance of the dominating bacteria in the salmon gut, with the freshwater microbiota being immature. Due to the low number of potentially host-associated bacterial species in the salmon gut, we believe that farmed salmon can represent an important model for future understanding of host-bacterium interactions in aquatic environments. IMPORTANCE Little is known about factors affecting the interindividual distribution of gut bacteria in aquatic environments. We have shown that there is a core of four highly prevalent and co-occurring bacteria irrespective of feed and freshwater-to-saltwater transition. The potential host interactions of the core bacteria, however, need to be elucidated further.

Authors: Knut Rudi, Inga Leena Angell, Phillip B. Pope, Jon Olav Vik, Simen Rød Sandve, Lars-Gustav Snipen

Date Published: 15th Jan 2018

Publication Type: Not specified

Abstract (Expand)

Amplified marker-gene sequences can be used to understand microbial community structure, but they suffer from a high level of sequencing and amplification artifacts. The UPARSE pipeline reports operational taxonomic unit (OTU) sequences with </=1% incorrect bases in artificial microbial community tests, compared with >3% incorrect bases commonly reported by other methods. The improved accuracy results in far fewer OTUs, consistently closer to the expected number of species in a community.

Author: R. C. Edgar

Date Published: 18th Aug 2013

Publication Type: Not specified

Abstract (Expand)

Plant and microbial metabolic engineering is commonly used in the production of functional foods and quality trait improvement. Computational model-based approaches have been used in this important endeavour. However, to date, fish metabolic models have only been scarcely and partially developed, in marked contrast to their prominent success in metabolic engineering. In this study we present the reconstruction of fully compartmentalised models of the Danio rerio (zebrafish) on a global scale. This reconstruction involves extraction of known biochemical reactions in D. rerio for both primary and secondary metabolism and the implementation of methods for determining subcellular localisation and assignment of enzymes. The reconstructed model (ZebraGEM) is amenable for constraint-based modelling analysis, and accounts for 4,988 genes coding for 2,406 gene-associated reactions and only 418 non-gene-associated reactions. A set of computational validations (i.e., simulations of known metabolic functionalities and experimental data) strongly testifies to the predictive ability of the model. Overall, the reconstructed model is expected to lay down the foundations for computational-based rational design of fish metabolic engineering in aquaculture.

Author: M. Bekaert

Date Published: 14th Nov 2012

Publication Type: Not specified

Abstract (Expand)

MOTIVATION: Biological sequence data is accumulating rapidly, motivating the development of improved high-throughput methods for sequence classification. RESULTS: UBLAST and USEARCH are new algorithms enabling sensitive local and global search of large sequence databases at exceptionally high speeds. They are often orders of magnitude faster than BLAST in practical applications, though sensitivity to distant protein relationships is lower. UCLUST is a new clustering method that exploits USEARCH to assign sequences to clusters. UCLUST offers several advantages over the widely used program CD-HIT, including higher speed, lower memory use, improved sensitivity, clustering at lower identities and classification of much larger datasets. AVAILABILITY: Binaries are available at no charge for non-commercial use at http://www.drive5.com/usearch.

Author: R. C. Edgar

Date Published: 12th Aug 2010

Publication Type: Not specified

Abstract

Not specified

Authors: J. G. Caporaso, J. Kuczynski, J. Stombaugh, K. Bittinger, F. D. Bushman, E. K. Costello, N. Fierer, A. G. Pena, J. K. Goodrich, J. I. Gordon, G. A. Huttley, S. T. Kelley, D. Knights, J. E. Koenig, R. E. Ley, C. A. Lozupone, D. McDonald, B. D. Muegge, M. Pirrung, J. Reeder, J. R. Sevinsky, P. J. Turnbaugh, W. A. Walters, J. Widmann, T. Yatsunenko, J. Zaneveld, R. Knight

Date Published: 11th Apr 2010

Publication Type: Not specified

Abstract (Expand)

Microarray analysis has become a widely used tool for the generation of gene expression data on a genomic scale. Although many significant results have been derived from microarray studies, one limitation has been the lack of standards for presenting and exchanging such data. Here we present a proposal, the Minimum Information About a Microarray Experiment (MIAME), that describes the minimum information required to ensure that microarray data can be easily interpreted and that results derived from its analysis can be independently verified. The ultimate goal of this work is to establish a standard for recording and reporting microarray-based gene expression data, which will in turn facilitate the establishment of databases and public repositories and enable the development of data analysis tools. With respect to MIAME, we concentrate on defining the content and structure of the necessary information rather than the technical format for capturing it.

Authors: A. Brazma, P. Hingamp, J. Quackenbush, G. Sherlock, P. Spellman, C. Stoeckert, J. Aach, W. Ansorge, C. A. Ball, H. C. Causton, T. Gaasterland, P. Glenisson, F. C. Holstege, I. F. Kim, V. Markowitz, J. C. Matese, H. Parkinson, A. Robinson, U. Sarkans, S. Schulze-Kremer, J. Stewart, R. Taylor, J. Vilo, M. Vingron

Date Published: 1st Dec 2001

Publication Type: Not specified

Abstract (Expand)

Atlantic salmon migrates from rivers to sea to feed, grow and develop gonads before returning to spawn in freshwater. The transition to marine habitats is associated with dramatic changes in the environment, including water salinity, exposure to pathogens, and shift in dietary lipid availability. Many changes in physiology and metabolism occur across this life-stage transition, but little is known about the molecular nature of these changes. Here we use a long term feeding experiment to study transcriptional regulation of lipid metabolism in Atlantic salmon gut and liver in both fresh- and saltwater. We find that lipid metabolism becomes significantly less plastic to differences in dietary lipid composition when salmon transitions to saltwater and experiences increased dietary lipid availability. Expression of genes in liver relating to lipogenesis and lipid transport decrease overall and become less responsive to diet, while genes for lipid uptake in gut become more highly expressed. Finally, analyses of evolutionary consequences of the salmonid specific whole-genome duplication on lipid metabolism reveals several pathways with significantly different (p<0.05) duplicate retention or duplicate regulatory conservation. We also find a limited number of cases where the whole genome duplication has resulted in an increased gene dosage. In conclusion, we find variable and pathway-specific effects of the salmonid genome duplication on lipid metabolism genes. A clear life-stage associated shift in lipid metabolism regulation is evident, and we hypothesize this to be, at least partly, driven by non-dietary factors such as the preparatory remodeling of gene regulation and physiology prior to sea migration. This article is protected by copyright. All rights reserved.

Authors: G. Gillard, T. N. Harvey, A. Gjuvsland, Y. Jin, M. Thomassen, S. Lien, M. Leaver, J. S. Torgersen, T. R. Hvidsten, J. O. Vik, S. R. Sandve

Date Published: No date defined

Publication Type: Not specified

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