1
|
Seeber PA, Batke L, Dvornikov Y, Schmidt A, Wang Y, Stoof-Leichsenring K, Moon K, Vohr SH, Shapiro B, Epp LS. Mitochondrial genomes of Pleistocene megafauna retrieved from recent sediment layers of two Siberian lakes. eLife 2024; 12:RP89992. [PMID: 38488477 PMCID: PMC10942779 DOI: 10.7554/elife.89992] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/17/2024] Open
Abstract
Ancient environmental DNA (aeDNA) from lake sediments has yielded remarkable insights for the reconstruction of past ecosystems, including suggestions of late survival of extinct species. However, translocation and lateral inflow of DNA in sediments can potentially distort the stratigraphic signal of the DNA. Using three different approaches on two short lake sediment cores of the Yamal peninsula, West Siberia, with ages spanning only the past hundreds of years, we detect DNA and identified mitochondrial genomes of multiple mammoth and woolly rhinoceros individuals-both species that have been extinct for thousands of years on the mainland. The occurrence of clearly identifiable aeDNA of extinct Pleistocene megafauna (e.g. >400 K reads in one core) throughout these two short subsurface cores, along with specificities of sedimentology and dating, confirm that processes acting on regional scales, such as extensive permafrost thawing, can influence the aeDNA record and should be accounted for in aeDNA paleoecology.
Collapse
Affiliation(s)
| | - Laura Batke
- Department of Biology, University of Konstanz, Konstanz, Germany
| | - Yury Dvornikov
- Agroengineering Department/Department of Landscape Design and Sustainable Ecosystems, Agrarian and Technological Institute, RUDN University, Moscow, Russian Federation
- Laboratory of Carbon Monitoring in Terrestrial Ecosystems, Institute of Physicochemical and Biological Problems of Soil Science of the Russian Academy of Sciences, Pushchino, Russian Federation
| | | | - Yi Wang
- Department of Biology, University of Konstanz, Konstanz, Germany
| | - Kathleen Stoof-Leichsenring
- Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research, Polar Terrestrial Environmental Systems, Potsdam, Germany
| | - Katie Moon
- Department of Ecology and Evolutionary Biology, University of California, Santa Cruz, Santa Cruz, United States
- Howard Hughes Medical Institute, University of California, Santa Cruz, Santa Cruz, United States
| | | | - Beth Shapiro
- Department of Ecology and Evolutionary Biology, University of California, Santa Cruz, Santa Cruz, United States
- Howard Hughes Medical Institute, University of California, Santa Cruz, Santa Cruz, United States
| | - Laura S Epp
- Department of Biology, University of Konstanz, Konstanz, Germany
| |
Collapse
|
2
|
Benthic Foraminiferal Indices and Environmental Quality Assessment of Transitional Waters: A Review of Current Challenges and Future Research Perspectives. WATER 2021. [DOI: 10.3390/w13141898] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Transitional waters straddle the interface between marine and terrestrial biomes and, among others, include fjords, bays, lagoons, and estuaries. These coastal systems are essential for transport and manufacturing industries and suffer extensive anthropogenic exploitation of their ecosystem services for aquaculture and recreational activities. These activities can have negative effects on the local biota, necessitating investigation and regulation. As a result of this, EcoQS (ecological quality status) assessment has garnered great attention as an essential aspect of governmental bodies’ legislative decision-making process. Assessing EcoQS in transitional water ecosystems is problematic because these systems experience high natural variability and organic enrichment and often lack information about their pre-human impact, baseline, or “pristine” reference conditions, knowledge of which is essential to many commonly used assessment methods. Here, foraminifera can be used as environmental sentinels, providing ecological data such as diversity and sensitivity, which can be used as the basis for EcoQS assessment indices. Fossil shells of foraminifera can also provide a temporal aspect to ecosystem assessment, making it possible to obtain reference conditions from the study site itself. These foraminifera-based indices have been shown to correlate not only with various environmental stressors but also with the most common macrofaunal-based indices currently employed by bodies such as the Water Framework Directive (WFD). In this review, we firstly discuss the development of various foraminifera-based indices and address the challenge of how best to implement these synergistically to understand and regulate human environmental impact, particularly in transitional waters, which have historically suffered disproportionate levels of human impact or are difficult to assess with standard EcoQS methods. Further, we present some case studies to exemplify key issues and discuss potential solutions for those. Such key issues include, for example, the disparate performance of multiple indices applied to the same site and a proper assignment of EcoQS class boundaries (threshold values) for each index. Disparate aptitudes of indices to specific geomorphologic and hydrological regimes can be leveraged via the development of a site characteristics catalogue, which would enable the identification of the most appropriate index to apply, and the integration of multiple indices resulting in more representative EcoQS assessment in heterogenous transitional environments. In addition, the difficulty in assigning threshold values to systems without analogous unimpacted reference sites (a common issue among many transitional waters) can be overcome by recording EcoQS as an ecological quality ratio (EQR). Lastly, we evaluate the current status and future potential of an emerging field, genetic biomonitoring, focusing on how these new techniques can be used to increase the accuracy of EcoQS assessment in transitional systems by supplementing more established morphology-based methods.
Collapse
|
3
|
Lake Sedimentary DNA Research on Past Terrestrial and Aquatic Biodiversity: Overview and Recommendations. QUATERNARY 2021. [DOI: 10.3390/quat4010006] [Citation(s) in RCA: 47] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The use of lake sedimentary DNA to track the long-term changes in both terrestrial and aquatic biota is a rapidly advancing field in paleoecological research. Although largely applied nowadays, knowledge gaps remain in this field and there is therefore still research to be conducted to ensure the reliability of the sedimentary DNA signal. Building on the most recent literature and seven original case studies, we synthesize the state-of-the-art analytical procedures for effective sampling, extraction, amplification, quantification and/or generation of DNA inventories from sedimentary ancient DNA (sedaDNA) via high-throughput sequencing technologies. We provide recommendations based on current knowledge and best practises.
Collapse
|
4
|
Pawłowska J, Wollenburg JE, Zajączkowski M, Pawlowski J. Planktonic foraminifera genomic variations reflect paleoceanographic changes in the Arctic: evidence from sedimentary ancient DNA. Sci Rep 2020; 10:15102. [PMID: 32934321 PMCID: PMC7492196 DOI: 10.1038/s41598-020-72146-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2020] [Accepted: 07/08/2020] [Indexed: 11/09/2022] Open
Abstract
Deciphering the evolution of marine plankton is typically based on the study of microfossil groups. Cryptic speciation is common in these groups, and large intragenomic variations occur in ribosomal RNA genes of many morphospecies. In this study, we correlated the distribution of ribosomal amplicon sequence variants (ASVs) with paleoceanographic changes by analyzing the high-throughput sequence data assigned to Neogloboquadrina pachyderma in a 140,000-year-old sediment core from the Arctic Ocean. The sedimentary ancient DNA demonstrated the occurrence of various N. pachyderma ASVs whose occurrence and dominance varied through time. Most remarkable was the striking appearance of ASV18, which was nearly absent in older sediments but became dominant during the last glacial maximum and continues to persist today. Although the molecular ecology of planktonic foraminifera is still poorly known, the analysis of their intragenomic variations through time has the potential to provide new insight into the evolution of marine biodiversity and may lead to the development of new and important paleoceanographic proxies.
Collapse
Affiliation(s)
- Joanna Pawłowska
- Institute of Oceanology Polish Academy of Sciences, Sopot, Poland.
| | | | | | - Jan Pawlowski
- Institute of Oceanology Polish Academy of Sciences, Sopot, Poland.,University of Geneva, Geneva, Switzerland
| |
Collapse
|
5
|
The potential of sedimentary ancient DNA for reconstructing past sea ice evolution. ISME JOURNAL 2019; 13:2566-2577. [PMID: 31235841 PMCID: PMC6776040 DOI: 10.1038/s41396-019-0457-1] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/15/2019] [Revised: 05/02/2019] [Accepted: 05/24/2019] [Indexed: 11/24/2022]
Abstract
Sea ice is a crucial component of the Arctic climate system, yet the tools to document the evolution of sea ice conditions on historical and geological time scales are few and have limitations. Such records are essential for documenting and understanding the natural variations in Arctic sea ice extent. Here we explore sedimentary ancient DNA (aDNA), as a novel tool that unlocks and exploits the genetic (eukaryote) biodiversity preserved in marine sediments specifically for past sea ice reconstructions. Although use of sedimentary aDNA in paleoceanographic and paleoclimatic studies is still in its infancy, we use here metabarcoding and single-species quantitative DNA detection methods to document the sea ice conditions in a Greenland Sea marine sediment core. Metabarcoding has allowed identifying biodiversity changes in the geological record back to almost ~100,000 years ago that were related to changing sea ice conditions. Detailed bioinformatic analyses on the metabarcoding data revealed several sea-ice-associated taxa, most of which previously unknown from the fossil record. Finally, we quantitatively traced one known sea ice dinoflagellate in the sediment core. We show that aDNA can be recovered from deep-ocean sediments with generally oxic bottom waters and that past sea ice conditions can be documented beyond instrumental time scales. Our results corroborate sea ice reconstructions made by traditional tools, and thus demonstrate the potential of sedimentary aDNA, focusing primarily on microbial eukaryotes, as a new tool to better understand sea ice evolution in the climate system.
Collapse
|
6
|
Torti A, Jørgensen BB, Lever MA. Preservation of microbial DNA in marine sediments: insights from extracellular DNA pools. Environ Microbiol 2018; 20:4526-4542. [PMID: 30198168 DOI: 10.1111/1462-2920.14401] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2018] [Revised: 07/04/2018] [Accepted: 09/05/2018] [Indexed: 01/15/2023]
Abstract
Marine sediments harbour extracellular DNA (exDNA) not associated with currently living organisms. Including this exDNA in genetic surveys may distort abundance and diversity estimates of living prokaryotic communities. We separately extract exDNA and intracellular DNA (inDNA) from 11 horizons in a 10-m deep sediment core from Aarhus Bay (Denmark) that spans > 9000 years of Holocene sedimentation. We compare depth profiles of bacterial and archaeal 16S rRNA gene compositions to those of macrofaunal activity (bioturbation), sulfate and methane concentrations, sediment age and lithology. Among these variables, bioturbation shows the strongest relationship with the two DNA pools. In bioturbated surface sediments, the majority of Operational Taxonomic Units (OTUs) present in exDNA is absent from inDNA, thus belonging to microorganisms that were not alive at the time of sampling. Below the bioturbation zone, the two DNA pools display a much higher phylogenetic similarity. At all depths, the majority of exDNA and inDNA sequences show highest sequence similarities to sediment microorganisms, a finding that is additionally supported by separate analyses on low- and high-molecular weight exDNA. Our results indicate that in Aarhus Bay the vast majority of prokaryotic exDNA is turned over, thus not contributing to a genetic archive of past environmental change.
Collapse
Affiliation(s)
- Andrea Torti
- Department of Bioscience, Center for Geomicrobiology, Aarhus University, Aarhus, Denmark
| | - Bo Barker Jørgensen
- Department of Bioscience, Center for Geomicrobiology, Aarhus University, Aarhus, Denmark
| | - Mark Alexander Lever
- Department of Bioscience, Center for Geomicrobiology, Aarhus University, Aarhus, Denmark.,Department of Environmental Systems Science, Institute of Biogeochemistry and Pollutant Dynamics, ETH Zurich, Zurich, Switzerland
| |
Collapse
|
7
|
Hou W, Wang S, Briggs BR, Li G, Xie W, Dong H. High Diversity of Myocyanophage in Various Aquatic Environments Revealed by High-Throughput Sequencing of Major Capsid Protein Gene With a New Set of Primers. Front Microbiol 2018; 9:887. [PMID: 29774020 PMCID: PMC5943533 DOI: 10.3389/fmicb.2018.00887] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2018] [Accepted: 04/18/2018] [Indexed: 12/02/2022] Open
Abstract
Myocyanophages, a group of viruses infecting cyanobacteria, are abundant and play important roles in elemental cycling. Here we investigated the particle-associated viral communities retained on 0.2 μm filters and in sediment samples (representing ancient cyanophage communities) from four ocean and three lake locations, using high-throughput sequencing and a newly designed primer pair targeting a gene fragment (∼145-bp in length) encoding the cyanophage gp23 major capsid protein (MCP). Diverse viral communities were detected in all samples. The fragments of 142-, 145-, and 148-bp in length were most abundant in the amplicons, and most sequences (>92%) belonged to cyanophages. Additionally, different sequencing depths resulted in different diversity estimates of the viral community. Operational taxonomic units obtained from deep sequencing of the MCP gene covered the majority of those obtained from shallow sequencing, suggesting that deep sequencing exhibited a more complete picture of cyanophage community than shallow sequencing. Our results also revealed a wide geographic distribution of marine myocyanophages, i.e., higher dissimilarities of the myocyanophage communities corresponded with the larger distances between the sampling sites. Collectively, this study suggests that the newly designed primer pair can be effectively used to study the community and diversity of myocyanophage from different environments, and the high-throughput sequencing represents a good method to understand viral diversity.
Collapse
Affiliation(s)
- Weiguo Hou
- State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Beijing, China
| | - Shang Wang
- CAS Key Laboratory of Environmental Biotechnology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences (CAS), Beijing, China
| | - Brandon R Briggs
- Department of Biological Sciences, University of Alaska Anchorage, Anchorage, AK, United States
| | - Gaoyuan Li
- State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Beijing, China
| | - Wei Xie
- State Key Laboratory of Marine Geology, Tongji University, Shanghai, China
| | - Hailiang Dong
- State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Beijing, China.,Department of Geology and Environmental Earth Science, Miami University, Oxford, OH, United States
| |
Collapse
|
8
|
End-member modelling as a tool for climate reconstruction-An Eastern Mediterranean case study. PLoS One 2017; 12:e0185136. [PMID: 28934332 PMCID: PMC5608325 DOI: 10.1371/journal.pone.0185136] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2017] [Accepted: 09/05/2017] [Indexed: 11/19/2022] Open
Abstract
The Eastern Mediterranean Sea is a sink for terrigenous sediments from North Africa, Europe and Asia Minor. Its sediments therefore provide valuable information on the climate dynamics in the source areas and the associated transport processes. We present a high-resolution dataset of sediment core M40/4_SL71, which was collected SW of Crete and spans the last ca. 180 kyr. We analysed the clay mineral composition, the grain size distribution within the silt fraction, and the abundance of major and trace elements. We tested the potential of end-member modelling on these sedimentological datasets as a tool for reconstructing the climate variability in the source regions and the associated detrital input. For each dataset, we modelled three end members. All end members were assigned to a specific provenance and sedimentary process. In total, three end members were related to the Saharan dust input, and five were related to the fluvial sediment input. One end member was strongly associated with the sapropel layers. The Saharan dust end members of the grain size and clay mineral datasets generally suggest enhanced dust export into the Eastern Mediterranean Sea during the dry phases with short-term increases during Heinrich events. During the African Humid Periods, dust export was reduced but may not have completely ceased. The loading patterns of two fluvial end members show a strong relationship with the Northern Hemisphere insolation, and all fluvial end members document enhanced input during the African Humid Periods. The sapropel end member most likely reflects the fixation of redox-sensitive elements within the anoxic sapropel layers. Our results exemplify that end-member modelling is a valuable tool for interpreting extensive and multidisciplinary datasets.
Collapse
|
9
|
Kouduka M, Tanabe AS, Yamamoto S, Yanagawa K, Nakamura Y, Akiba F, Tomaru H, Toju H, Suzuki Y. Eukaryotic diversity in late Pleistocene marine sediments around a shallow methane hydrate deposit in the Japan Sea. GEOBIOLOGY 2017; 15:715-727. [PMID: 28434198 DOI: 10.1111/gbi.12233] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/19/2016] [Accepted: 01/25/2017] [Indexed: 06/07/2023]
Abstract
Marine sediments contain eukaryotic DNA deposited from overlying water columns. However, a large proportion of deposited eukaryotic DNA is aerobically biodegraded in shallow marine sediments. Cold seep sediments are often anaerobic near the sediment-water interface, so eukaryotic DNA in such sediments is expected to be preserved. We investigated deeply buried marine sediments in the Japan Sea, where a methane hydrate deposit is associated with cold seeps. Quantitative PCR analysis revealed the reproducible recovery of eukaryotic DNA in marine sediments at depths up to 31.0 m in the vicinity of the methane hydrate deposit. In contrast, the reproducible recovery of eukaryotic DNA was limited to a shallow depth (8.3 m) in marine sediments not adjacent to the methane hydrate deposit in the same area. Pyrosequencing of an 18S rRNA gene variable region generated 1,276-3,307 reads per sample, which was sufficient to cover the biodiversity based on rarefaction curves. Phylogenetic analysis revealed that most of the eukaryotic DNA originated from radiolarian genera of the class Chaunacanthida, which have SrSO4 skeletons, the sea grass genus Zostera, and the seaweed genus Sargassum. Eukaryotic DNA originating from other planktonic fauna and land plants was also detected. Diatom sequences closely related to Thalassiosira spp., indicative of cold climates, were obtained from sediments deposited during the last glacial period (MIS-2). Plant sequences of the genera Alnus, Micromonas, and Ulmus were found in sediments deposited during the warm interstadial period (MIS-3). These results suggest the long-term persistence of eukaryotic DNA from terrestrial and aquatic sources in marine sediments associated with cold seeps, and that the genetic information from eukaryotic DNA from deeply buried marine sediments associated with cold seeps can be used to reconstruct environments and ecosystems from the past.
Collapse
Affiliation(s)
- M Kouduka
- Department of Earth and Planetary Science, The University of Tokyo, Tokyo, Japan
| | - A S Tanabe
- Graduate School of Science, Kobe University, Kobe, Japan
| | - S Yamamoto
- Graduate School of Human Development and Environment, Kobe University, Kobe, Japan
| | - K Yanagawa
- Graduate School of Social and Cultural Studies, Kyushu University, Fukuoka, Japan
| | - Y Nakamura
- Institute of Geology and Geoinformation, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Japan
| | - F Akiba
- Diatom Minilab Akiba Ltd., Saitama, Japan
| | - H Tomaru
- Department of Earth Sciences, Graduate School of Science, Chiba University, Chiba, Japan
| | - H Toju
- Graduate School of Human and Environmental Studies, Kyoto University, Kyoto, Japan
| | - Y Suzuki
- Department of Earth and Planetary Science, The University of Tokyo, Tokyo, Japan
| |
Collapse
|
10
|
Vuillemin A, Horn F, Alawi M, Henny C, Wagner D, Crowe SA, Kallmeyer J. Preservation and Significance of Extracellular DNA in Ferruginous Sediments from Lake Towuti, Indonesia. Front Microbiol 2017; 8:1440. [PMID: 28798742 PMCID: PMC5529349 DOI: 10.3389/fmicb.2017.01440] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2017] [Accepted: 07/17/2017] [Indexed: 01/20/2023] Open
Abstract
Extracellular DNA is ubiquitous in soil and sediment and constitutes a dominant fraction of environmental DNA in aquatic systems. In theory, extracellular DNA is composed of genomic elements persisting at different degrees of preservation produced by processes occurring on land, in the water column and sediment. Extracellular DNA can be taken up as a nutrient source, excreted or degraded by microorganisms, or adsorbed onto mineral matrices, thus potentially preserving information from past environments. To test whether extracellular DNA records lacustrine conditions, we sequentially extracted extracellular and intracellular DNA from anoxic sediments of ferruginous Lake Towuti, Indonesia. We applied 16S rRNA gene Illumina sequencing on both fractions to discriminate exogenous from endogenous sources of extracellular DNA in the sediment. Environmental sequences exclusively found as extracellular DNA in the sediment originated from multiple sources. For instance, Actinobacteria, Verrucomicrobia, and Acidobacteria derived from soils in the catchment. Limited primary productivity in the water column resulted in few sequences of Cyanobacteria in the oxic photic zone, whereas stratification of the water body mainly led to secondary production by aerobic and anaerobic heterotrophs. Chloroflexi and Planctomycetes, the main degraders of sinking organic matter and planktonic sequences at the water-sediment interface, were preferentially preserved during the initial phase of burial. To trace endogenous sources of extracellular DNA, we used relative abundances of taxa in the intracellular DNA to define which microbial populations grow, decline or persist at low density with sediment depth. Cell lysis became an important additional source of extracellular DNA, gradually covering previous genetic assemblages as other microbial genera became more abundant with depth. The use of extracellular DNA as nutrient by active microorganisms led to selective removal of sequences with lowest GC contents. We conclude that extracellular DNA preserved in shallow lacustrine sediments reflects the initial environmental context, but is gradually modified and thereby shifts from its stratigraphic context. Discrimination of exogenous and endogenous sources of extracellular DNA allows simultaneously addressing in-lake and post-depositional processes. In deeper sediments, the accumulation of resting stages and sequences from cell lysis would require stringent extraction and specific primers if ancient DNA is targeted.
Collapse
Affiliation(s)
- Aurèle Vuillemin
- GFZ German Research Centre for Geosciences, Section 5.3: GeomicrobiologyPotsdam, Germany
| | - Fabian Horn
- GFZ German Research Centre for Geosciences, Section 5.3: GeomicrobiologyPotsdam, Germany
| | - Mashal Alawi
- GFZ German Research Centre for Geosciences, Section 5.3: GeomicrobiologyPotsdam, Germany
| | - Cynthia Henny
- Research Center for Limnology, Indonesian Institute of SciencesCibinong-Bogor, Indonesia
| | - Dirk Wagner
- GFZ German Research Centre for Geosciences, Section 5.3: GeomicrobiologyPotsdam, Germany
| | - Sean A. Crowe
- Department of Microbiology and Immunology, University of British Columbia, VancouverBC, Canada
- Department of Earth, Ocean, and Atmospheric Sciences, University of British Columbia, VancouverBC, Canada
| | - Jens Kallmeyer
- GFZ German Research Centre for Geosciences, Section 5.3: GeomicrobiologyPotsdam, Germany
| |
Collapse
|
11
|
Capo E, Debroas D, Arnaud F, Perga ME, Chardon C, Domaizon I. Tracking a century of changes in microbial eukaryotic diversity in lakes driven by nutrient enrichment and climate warming. Environ Microbiol 2017; 19:2873-2892. [DOI: 10.1111/1462-2920.13815] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2016] [Revised: 05/21/2017] [Accepted: 05/30/2017] [Indexed: 11/28/2022]
Affiliation(s)
- Eric Capo
- CARRTEL, INRA, Université de Savoie Mont Blanc; Thonon-les-bains 74200 France
| | - Didier Debroas
- Université Clermont Auvergne, Université Blaise Pascal, Laboratoire «Microorganismes: Génome et Environnement»; BP 10448 Clermont-Ferrand 63000 France
- CNRS, UMR 6023, LMGE; Campus Universitaire des Cézeaux, 63171 Aubière France
| | - Fabien Arnaud
- CNRS, UMR 5204 EDYTEM, Université Savoie Mont Blanc; Le Bourget du Lac Cedex France
| | - Marie-Elodie Perga
- CARRTEL, INRA, Université de Savoie Mont Blanc; Thonon-les-bains 74200 France
| | - Cécile Chardon
- CARRTEL, INRA, Université de Savoie Mont Blanc; Thonon-les-bains 74200 France
| | - Isabelle Domaizon
- CARRTEL, INRA, Université de Savoie Mont Blanc; Thonon-les-bains 74200 France
| |
Collapse
|
12
|
Simdyanov TG, Guillou L, Diakin AY, Mikhailov KV, Schrével J, Aleoshin VV. A new view on the morphology and phylogeny of eugregarines suggested by the evidence from the gregarine Ancora sagittata (Leuckart, 1860) Labbé, 1899 (Apicomplexa: Eugregarinida). PeerJ 2017; 5:e3354. [PMID: 28584702 PMCID: PMC5452951 DOI: 10.7717/peerj.3354] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2016] [Accepted: 04/26/2017] [Indexed: 11/20/2022] Open
Abstract
BACKGROUND Gregarines are a group of early branching Apicomplexa parasitizing invertebrate animals. Despite their wide distribution and relevance to the understanding the phylogenesis of apicomplexans, gregarines remain understudied: light microscopy data are insufficient for classification, and electron microscopy and molecular data are fragmentary and overlap only partially. METHODS Scanning and transmission electron microscopy, PCR, DNA cloning and sequencing (Sanger and NGS), molecular phylogenetic analyses using ribosomal RNA genes (18S (SSU), 5.8S, and 28S (LSU) ribosomal DNAs (rDNAs)). RESULTS AND DISCUSSION We present the results of an ultrastructural and molecular phylogenetic study on the marine gregarine Ancora sagittata from the polychaete Capitella capitata followed by evolutionary and taxonomic synthesis of the morphological and molecular phylogenetic evidence on eugregarines. The ultrastructure of Ancora sagittata generally corresponds to that of other eugregarines, but reveals some differences in epicytic folds (crests) and attachment apparatus to gregarines in the family Lecudinidae, where Ancora sagittata has been classified. Molecular phylogenetic trees based on SSU (18S) rDNA reveal several robust clades (superfamilies) of eugregarines, including Ancoroidea superfam. nov., which comprises two families (Ancoridae fam. nov. and Polyplicariidae) and branches separately from the Lecudinidae; thus, all representatives of Ancoroidea are here officially removed from the Lecudinidae. Analysis of sequence data also points to possible cryptic species within Ancora sagittata and the inclusion of numerous environmental sequences from anoxic habitats within the Ancoroidea. LSU (28S) rDNA phylogenies, unlike the analysis of SSU rDNA alone, recover a well-supported monophyly of the gregarines involved (eugregarines), although this conclusion is currently limited by sparse taxon sampling and the presence of fast-evolving sequences in some species. Comparative morphological analyses of gregarine teguments and attachment organelles lead us to revise their terminology. The terms "longitudinal folds" and "mucron" are restricted to archigregarines, whereas the terms "epicystic crests" and "epimerite" are proposed to describe the candidate synapomorphies of eugregarines, which, consequently, are considered as a monophyletic group. Abolishing the suborders Aseptata and Septata, incorporating neogregarines into the Eugregarinida, and treating the major molecular phylogenetic lineages of eugregarines as superfamilies appear as the best way of reconciling recent morphological and molecular evidence. Accordingly, the diagnosis of the order Eugregarinida Léger, 1900 is updated.
Collapse
Affiliation(s)
- Timur G. Simdyanov
- Faculty of Biology, Department of Invertebrate Zoology, Lomonosov Moscow State University, Moscow, Russian Federation
| | - Laure Guillou
- UMR 7144, Laboratoire Adaptation et Diversité en Milieu Marin, CNRS, Paris, Roscoff, France
- UMR 7144, Station Biologique de Roscoff, CNRS, Sorbonne Universités, Université Pierre et Marie Curie - Paris 6, Paris, Roscoff, France
| | - Andrei Y. Diakin
- Faculty of Science, Department of Botany and Zoology, Masaryk University, Brno, Czech Republic
| | - Kirill V. Mikhailov
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, Russian Federation
- Institute for Information Transmission Problems, Russian Academy of Sciences, Moscow, Russian Federation
| | - Joseph Schrével
- CNRS 7245, Molécules de Communication et Adaptation of Micro-organisms, Paris, France
- Muséum National d’Histoire Naturelle, UMR 7245, Sorbonne Universités, Paris, France
| | - Vladimir V. Aleoshin
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, Russian Federation
- Institute for Information Transmission Problems, Russian Academy of Sciences, Moscow, Russian Federation
| |
Collapse
|
13
|
Slon V, Hopfe C, Weiß CL, Mafessoni F, de la Rasilla M, Lalueza-Fox C, Rosas A, Soressi M, Knul MV, Miller R, Stewart JR, Derevianko AP, Jacobs Z, Li B, Roberts RG, Shunkov MV, de Lumley H, Perrenoud C, Gušić I, Kućan Ž, Rudan P, Aximu-Petri A, Essel E, Nagel S, Nickel B, Schmidt A, Prüfer K, Kelso J, Burbano HA, Pääbo S, Meyer M. Neandertal and Denisovan DNA from Pleistocene sediments. Science 2017; 356:605-608. [DOI: 10.1126/science.aam9695] [Citation(s) in RCA: 215] [Impact Index Per Article: 30.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2017] [Accepted: 04/07/2017] [Indexed: 12/11/2022]
|
14
|
Lundholm N, Ribeiro S, Godhe A, Rostgaard Nielsen L, Ellegaard M. Exploring the impact of multidecadal environmental changes on the population genetic structure of a marine primary producer. Ecol Evol 2017; 7:3132-3142. [PMID: 28480012 PMCID: PMC5415532 DOI: 10.1002/ece3.2906] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2016] [Revised: 02/13/2017] [Accepted: 02/21/2017] [Indexed: 01/29/2023] Open
Abstract
Many marine protists form resting stages that can remain viable in coastal sediments for several decades. Their long‐term survival offers the possibility to explore the impact of changes in environmental conditions on population dynamics over multidecadal time scales. Resting stages of the phototrophic dinoflagellate Pentapharsodinium dalei were isolated and germinated from five layers in dated sediment cores from Koljö fjord, Sweden, spanning ca. 1910–2006. This fjord has, during the last century, experienced environmental fluctuations linked to hydrographic variability mainly driven by the North Atlantic Oscillation. Population genetic analyses based on six microsatellite markers revealed high genetic diversity and suggested that samples belonged to two clusters of subpopulations that have persisted for nearly a century. We observed subpopulation shifts coinciding with changes in hydrographic conditions. The large degree of genetic diversity and the potential for both fluctuation and recovery over longer time scales documented here, may help to explain the long‐term success of aquatic protists that form resting stages.
Collapse
Affiliation(s)
- Nina Lundholm
- The Natural History Museum of Denmark University of Copenhagen Copenhagen K Denmark
| | - Sofia Ribeiro
- Glaciology and Climate Department Geological Survey of Denmark and Greenland (GEUS) Copenhagen K Denmark
| | - Anna Godhe
- Department of Marine Sciences University of Gothenburg Göteborg Sweden
| | - Lene Rostgaard Nielsen
- Deparment of Geosciences and Natural Resource Management University of Copenhagen Frederiksberg Denmark
| | - Marianne Ellegaard
- Department of Plant and Environmental Sciences University of Copenhagen Frederiksberg Denmark
| |
Collapse
|
15
|
Cutting the Umbilical: New Technological Perspectives in Benthic Deep-Sea Research. JOURNAL OF MARINE SCIENCE AND ENGINEERING 2016. [DOI: 10.3390/jmse4020036] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
|
16
|
Klouch KZ, Schmidt S, Andrieux-Loyer F, Le Gac M, Hervio-Heath D, Qui-Minet ZN, Quéré J, Bigeard E, Guillou L, Siano R. Historical records from dated sediment cores reveal the multidecadal dynamic of the toxic dinoflagellateAlexandrium minutumin the Bay of Brest (France). FEMS Microbiol Ecol 2016; 92:fiw101. [DOI: 10.1093/femsec/fiw101] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/04/2016] [Indexed: 01/01/2023] Open
|
17
|
Temporal Succession of Ancient Phytoplankton Community in Qinghai Lake and Implication for Paleo-environmental Change. Sci Rep 2016; 6:19769. [PMID: 26805936 PMCID: PMC4726407 DOI: 10.1038/srep19769] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2015] [Accepted: 11/10/2015] [Indexed: 11/24/2022] Open
Abstract
Tibetan lake sediments in NW China are sensitive recorders of climate change. However, many important plankton members do not leave any microscopic features in sedimentary records. Here we used ancient DNA preserved in Qinghai Lake sediments to reconstruct the temporal succession of plankton communities in the past 18,500 years. Our results showed that seven classes and sixteen genera of phytoplankton in the lake underwent major temporal changes, in correlation with known climatic events. Trebouxiophyceae and Eustigmatophyceae were predominant during the cold periods, whereas Chlorophyceae, Phaeophyceae, Xanthophyceae, Bacillariophyceae, and Cyanophyceae were abundant during the warm periods. The inferred changes in temperature, nutrients, precipitation, and salinity, as driven by the Westerlies and summer Monsoon strength, likely contributed to these observed temporal changes. Based on these correlations, we propose the phytoplankton index as a proxy to reconstruct the stadial versus interstadial climate change history in Qinghai Lake. This taxon-specific index is free of terrestrial contamination, sensitive to short-term climatic oscillations, and continuous in recording all climatic events in the lake. The validity of this index and its applicability to other lakes is demonstrated by its good correlations with multiple climate records of Qinghai Lake and another lake on the Tibetan Plateau, Kusai Lake.
Collapse
|
18
|
Torti A, Lever MA, Jørgensen BB. Origin, dynamics, and implications of extracellular DNA pools in marine sediments. Mar Genomics 2015; 24 Pt 3:185-96. [DOI: 10.1016/j.margen.2015.08.007] [Citation(s) in RCA: 167] [Impact Index Per Article: 18.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2015] [Accepted: 08/29/2015] [Indexed: 12/17/2022]
|
19
|
Capo E, Debroas D, Arnaud F, Domaizon I. Is Planktonic Diversity Well Recorded in Sedimentary DNA? Toward the Reconstruction of Past Protistan Diversity. MICROBIAL ECOLOGY 2015; 70:865-75. [PMID: 26022714 DOI: 10.1007/s00248-015-0627-2] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/13/2014] [Accepted: 05/12/2015] [Indexed: 05/25/2023]
Abstract
Studies based on the coupling of a paleolimnological approach and molecular tools (e.g., sequencing of sedimentary DNA) present a promising opportunity to obtain long-term data on past lacustrine biodiversity. However, certain validations are still required, such as the evaluation of DNA preservation in sediments for various planktonic taxa that do not leave any morphological diagnostic features. In this study, we focused on the diversity of planktonic unicellular eukaryotes and verified the presence of their DNA in sediment archives. We compared the molecular inventories (high-throughput sequencing of 18S ribosomal DNA) obtained from monitoring the water column with those obtained for DNA archived in the first 30 cm of sediment. Seventy-one percent of taxonomic units found in the water samples were detected in sediment samples, including pigmented taxa, such as Chlorophyta, Dinophyceae, and Chrysophyceae, phagotrophic taxa, such as Ciliophora, parasitic taxa, such as Apicomplexa and Chytridiomycota, and saprotrophs, such as Cryptomycota. Parallel analysis of 18S ribosomal RNA (rRNA) transcripts revealed the presence of living eukaryotic taxa only in the top 2 cm of sediment; although some limits exist in using RNA/DNA ratio as indicator of microbial activity, these results suggested that the sedimentary DNA mostly represented DNA from past and inactive communities. Only the diversity of a few groups, such as Cryptophyta and Haptophyta, seemed to be poorly preserved in sediments. Our overall results showed that the application of sequencing techniques to sedimentary DNA could be used to reconstruct past diversity for numerous planktonic eukaryotic groups.
Collapse
Affiliation(s)
- Eric Capo
- INRA, UMR 42 CARRTEL, 74203, Thonon-les-bains Cedex, France
- Université Savoie Mont Blanc, UMR 42 CARRTEL, 73379, Le Bourget du Lac, France
| | - Didier Debroas
- Clermont Université, Université Blaise Pascal, CNRS, UMR 6023 LMGE, 63171, Aubière, France
| | - Fabien Arnaud
- CNRS, UMR 5204 EDYTEM, Université Savoie Mont Blanc, 73379, Le Bourget du Lac Cedex, France
| | | |
Collapse
|
20
|
Kyle M, Haande S, Ostermaier V, Rohrlack T. The Red Queen race between parasitic chytrids and their host, Planktothrix: a test using a time series reconstructed from sediment DNA. PLoS One 2015; 10:e0118738. [PMID: 25793898 PMCID: PMC4368186 DOI: 10.1371/journal.pone.0118738] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2014] [Accepted: 01/07/2015] [Indexed: 11/19/2022] Open
Abstract
Parasitic chytrid fungi (phylum Chytridiomycota) are known to infect specific phytoplankton, including the filamentous cyanobacterium Planktothrix. Subspecies, or chemotypes of Planktothrix can be identified by the presence of characteristic oligopeptides. Some of these oligopeptides can be associated with important health concerns due to their potential for toxin production. However, the relationship between chytrid parasite and Planktothrix host is not clearly understood and more research is needed. To test the parasite-host relationship over time, we used a sediment core extracted from a Norwegian lake known to contain both multiple Planktothrix chemotype hosts and their parasitic chytrid. Sediment DNA of chytrids and Planktothrix was amplified and a 35-year coexistence was found. It is important to understand how these two antagonistic species can coexistence in a lake. Reconstruction of the time series showed that between 1979-1990 at least 2 strains of Planktothrix were present and parasitic pressure exerted by chytrids was low. After this period one chemotype became dominant and yet showed continued low susceptibility to chytrid parasitism. Either environmental conditions or intrinsic characteristics of Planktothrix could have been responsible for this continued dominance. One possible explanation could be found in the shift of Planktothrix to the metalimnion, an environment that typically consists of low light and decreased temperatures. Planktothrix are capable of growth under these conditions while the chytrid parasites are constrained. Another potential explanation could be due to the differences between cellular oligopeptide variations found between Planktothrix chemotypes. These oligopeptides can function as defense systems against chytrids. Our findings suggest that chytrid driven diversity was not maintained over time, but that the combination of environmental constraints and multiple oligopeptide production to combat chytrids could have allowed one Planktothrix chemotype to have dominance despite chytrid presence.
Collapse
Affiliation(s)
- Marcia Kyle
- Norwegian University of Life Sciences (NMBU), Environmental Sciences, Ås, Norway
| | - Sigrid Haande
- Norwegian Institute for Water Research (NIVA), Oslo, Norway
| | | | - Thomas Rohrlack
- Norwegian University of Life Sciences (NMBU), Environmental Sciences, Ås, Norway
| |
Collapse
|
21
|
Pawłowska J, Lejzerowicz F, Esling P, Szczuciński W, Zajączkowski M, Pawlowski J. Ancient DNA sheds new light on the Svalbard foraminiferal fossil record of the last millennium. GEOBIOLOGY 2014; 12:277-288. [PMID: 24730667 DOI: 10.1111/gbi.12087] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/28/2013] [Accepted: 04/19/2014] [Indexed: 06/03/2023]
Abstract
Recent palaeogenetic studies have demonstrated the occurrence of preserved ancient DNA (aDNA) in various types of fossilised material. Environmental aDNA sequences assigned to modern species have been recovered from marine sediments dating to the Pleistocene. However, the match between the aDNA and the fossil record still needs to be evaluated for the environmental DNA approaches to be fully exploited. Here, we focus on foraminifera in sediments up to one thousand years old retrieved from the Hornsund fjord (Svalbard). We compared the diversity of foraminiferal microfossil assemblages with the diversity of aDNA sequenced from subsurface sediment samples using both cloning and high-throughput sequencing (HTS). Our study shows that 57% of the species archived in the fossil record were also detected in the aDNA data. However, the relative abundance of aDNA sequence reads and fossil specimens differed considerably. We also found a limited match between the stratigraphic occurrence of some fossil species and their aDNA sequences, especially in the case of rare taxa. The aDNA data comprised a high proportion of non-fossilised monothalamous species, which are known to dominate in modern foraminiferal communities of the Svalbard region. Our results confirm the relevance of HTS for studying past micro-eukaryotic diversity and provide insight into its ability to reflect fossil assemblages. Palaeogenetic studies including aDNA analyses of non-fossilised groups expand the range of palaeoceanographical proxies and therefore may increase the accuracy of palaeoenvironmental reconstructions.
Collapse
Affiliation(s)
- J Pawłowska
- Institute of Oceanology Polish Academy of Sciences, Sopot, Poland
| | | | | | | | | | | |
Collapse
|
22
|
Lejzerowicz F, Esling P, Majewski W, Szczuciński W, Decelle J, Obadia C, Arbizu PM, Pawlowski J. Ancient DNA complements microfossil record in deep-sea subsurface sediments. Biol Lett 2013; 9:20130283. [PMID: 23658006 DOI: 10.1098/rsbl.2013.0283] [Citation(s) in RCA: 77] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Deep-sea subsurface sediments are the most important archives of marine biodiversity. Until now, these archives were studied mainly using the microfossil record, disregarding large amounts of DNA accumulated on the deep-sea floor. Accessing ancient DNA (aDNA) molecules preserved down-core would offer unique insights into the history of marine biodiversity, including both fossilized and non-fossilized taxa. Here, we recover aDNA of eukaryotic origin across four cores collected at abyssal depths in the South Atlantic, in up to 32.5 thousand-year-old sediment layers. Our study focuses on Foraminifera and Radiolaria, two major groups of marine microfossils also comprising diverse non-fossilized taxa. We describe their assemblages in down-core sediment layers applying both micropalaeontological and environmental DNA sequencing approaches. Short fragments of the foraminiferal and radiolarian small subunit rRNA gene recovered from sedimentary DNA extracts provide evidence that eukaryotic aDNA is preserved in deep-sea sediments encompassing the last glacial maximum. Most aDNA were assigned to non-fossilized taxa that also dominate in molecular studies of modern environments. Our study reveals the potential of aDNA to better document the evolution of past marine ecosystems and opens new horizons for the development of deep-sea palaeogenomics.
Collapse
Affiliation(s)
- Franck Lejzerowicz
- Department of Genetics and Evolution, University of Geneva, Genève 4, Switzerland.
| | | | | | | | | | | | | | | |
Collapse
|
23
|
Orsi W, Biddle JF, Edgcomb V. Deep sequencing of subseafloor eukaryotic rRNA reveals active Fungi across marine subsurface provinces. PLoS One 2013; 8:e56335. [PMID: 23418556 PMCID: PMC3572030 DOI: 10.1371/journal.pone.0056335] [Citation(s) in RCA: 147] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2012] [Accepted: 01/08/2013] [Indexed: 02/01/2023] Open
Abstract
The deep marine subsurface is a vast habitat for microbial life where cells may live on geologic timescales. Because DNA in sediments may be preserved on long timescales, ribosomal RNA (rRNA) is suggested to be a proxy for the active fraction of a microbial community in the subsurface. During an investigation of eukaryotic 18S rRNA by amplicon pyrosequencing, unique profiles of Fungi were found across a range of marine subsurface provinces including ridge flanks, continental margins, and abyssal plains. Subseafloor fungal populations exhibit statistically significant correlations with total organic carbon (TOC), nitrate, sulfide, and dissolved inorganic carbon (DIC). These correlations are supported by terminal restriction length polymorphism (TRFLP) analyses of fungal rRNA. Geochemical correlations with fungal pyrosequencing and TRFLP data from this geographically broad sample set suggests environmental selection of active Fungi in the marine subsurface. Within the same dataset, ancient rRNA signatures were recovered from plants and diatoms in marine sediments ranging from 0.03 to 2.7 million years old, suggesting that rRNA from some eukaryotic taxa may be much more stable than previously considered in the marine subsurface.
Collapse
Affiliation(s)
- William Orsi
- Department of Geology and Geophysics, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts, United States of America.
| | | | | |
Collapse
|
24
|
Schippers A, Kock D, Höft C, Köweker G, Siegert M. Quantification of Microbial Communities in Subsurface Marine Sediments of the Black Sea and off Namibia. Front Microbiol 2012; 3:16. [PMID: 22319518 PMCID: PMC3268179 DOI: 10.3389/fmicb.2012.00016] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2011] [Accepted: 01/09/2012] [Indexed: 12/04/2022] Open
Abstract
Organic-rich subsurface marine sediments were taken by gravity coring up to a depth of 10 m below seafloor at six stations from the anoxic Black Sea and the Benguela upwelling system off Namibia during the research cruises Meteor 72-5 and 76-1, respectively. The quantitative microbial community composition at various sediment depths was analyzed using total cell counting, catalyzed reporter deposition – fluorescence in situ hybridization (CARD–FISH) and quantitative real-time PCR (Q-PCR). Total cell counts decreased with depths from 109 to 1010 cells/mL at the sediment surface to 107–109 cells/mL below one meter depth. Based on CARD–FISH and Q-PCR analyses overall similar proportions of Bacteria and Archaea were found. The down-core distribution of prokaryotic and eukaryotic small subunit ribosomal RNA genes (16S and 18S rRNA) as well as functional genes involved in different biogeochemical processes was quantified using Q-PCR. Crenarchaeota and the bacterial candidate division JS-1 as well as the classes Anaerolineae and Caldilineae of the phylum Chloroflexi were highly abundant. Less abundant but detectable in most of the samples were Eukarya as well as the metal and sulfate-reducing Geobacteraceae (only in the Benguela upwelling influenced sediments). The functional genes cbbL, encoding for the large subunit of RuBisCO, the genes dsrA and aprA, indicative of sulfate-reducers as well as the mcrA gene of methanogens were detected in the Benguela upwelling and Black Sea sediments. Overall, the high organic carbon content of the sediments goes along with high cell counts and high gene copy numbers, as well as an equal abundance of Bacteria and Archaea.
Collapse
Affiliation(s)
- Axel Schippers
- Geomicrobiology, Federal Institute for Geosciences and Natural Resources Hannover, Germany
| | | | | | | | | |
Collapse
|