scholarly journals An assessment of environmental metabarcoding protocols aiming at favouring contemporary biodiversity in inventories of deep-sea communities

2019 ◽  
Author(s):  
Miriam I. Brandt ◽  
Blandine Trouche ◽  
Nicolas Henry ◽  
Cathy Liautard-Haag ◽  
Lois Maignien ◽  
...  
Keyword(s):  
Spatial Patterns ◽  
Ancient Dna ◽  
Deep Sea ◽  
Messenger Rna ◽  
Environmental Dna ◽  
List Type ◽  
Dna Fragments ◽  
Large Reservoir ◽  
Alpha And Beta Diversity ◽  
Dna And Rna

ABSTRACTThe abyssal seafloor covers more than 50% of planet Earth and is a large reservoir of still mostly undescribed biodiversity. It is increasingly under target of resource-extraction industries although being drastically understudied. In such remote and hard-to-access ecosystems, environmental DNA (eDNA) metabarcoding is a useful and efficient tool for studying biodiversity and implementing environmental impact assessments. Yet, eDNA analysis outcomes may be biased towards describing past rather than present communities as sediments contain both contemporary and ancient DNA.Using commercially available kits, we investigated the impacts of five molecular processing methods on DNA metabarcoding biodiversity inventories targeting prokaryotes (16S-V4V5), unicellular eukaryotes (18S-V4), and metazoans (18S-V1, COI). As the size distribution of ancient DNA is skewed towards small fragments, we evaluated the effect of removing short DNA fragments via size-selection and ethanol reconcentration using DNA extracted from 10 g of sediment at five deep-sea sites. We also compare communities revealed by DNA and RNA co-extracted from 2 g of sediment at the same sites.Results show that removing short DNA fragments does not affect alpha and beta diversity estimates in any of the biological compartments investigated. Results also confirm doubts regarding the possibility to better describe live communities using environmental RNA (eRNA). With ribosomal loci, RNA, while resolving similar spatial patterns than co-extracted DNA, resulted in significantly higher richness estimates, supporting hypotheses of increased persistence of ribosomal RNA (rRNA) in the environment and unmeasured bias due to over-abundance of rRNA and RNA release. With the mitochondrial locus, RNA detected lower metazoan richness and resolved less spatial patterns than co-extracted DNA, reflecting high messenger RNA lability. Results also highlight the importance of using large amounts of sediment (≥10 g) for accurately surveying eukaryotic diversity.We conclude that DNA should be favoured over RNA for logistically realistic, repeatable, and reliable surveys, and confirm that large sediment samples (≥10 g) deliver more complete and accurate assessments of benthic eukaryotic biodiversity and that increasing the number of biological rather than technical replicates is important to infer robust ecological patterns.

scholarly journals Ancient DNA complements microfossil record in deep-sea subsurface sediments

2013 ◽  
Vol 9 (4) ◽  
pp. 20130283 ◽  
Author(s):  
Franck Lejzerowicz ◽  
Philippe Esling ◽  
Wojciech Majewski ◽  
Witold Szczuciński ◽  
Johan Decelle ◽  
...  
Keyword(s):  
Ancient Dna ◽  
Deep Sea ◽  
Environmental Dna ◽  
Small Subunit ◽  
Marine Biodiversity ◽  
Rrna Gene ◽  
Small Subunit Rrna ◽  
Core Sediment ◽  
Subsurface Sediments ◽  
Sediment Layers

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.

scholarly journals Eukaryotic Biodiversity and Spatial Patterns in the Clarion-Clipperton Zone and Other Abyssal Regions: Insights From Sediment DNA and RNA Metabarcoding

2021 ◽  
Vol 8 ◽  
Author(s):  
Franck Lejzerowicz ◽  
Andrew John Gooday ◽  
Inés Barrenechea Angeles ◽  
Tristan Cordier ◽  
Raphaël Morard ◽  
...  
Keyword(s):  
Deep Sea ◽  
Large Scale ◽  
Benthic Communities ◽  
Experimental Studies ◽  
Alpha Diversity ◽  
Environmental Dna ◽  
18S Rrna Gene ◽  
Rrna Gene ◽  
Data Resource ◽  
Dna And Rna

The abyssal seafloor is a mosaic of highly diverse habitats that represent the least known marine ecosystems on Earth. Some regions enriched in natural resources, such as polymetallic nodules in the Clarion-Clipperton Zone (CCZ), attract much interest because of their huge commercial potential. Since nodule mining will be destructive, baseline data are necessary to measure its impact on benthic communities. Hence, we conducted an environmental DNA and RNA metabarcoding survey of CCZ biodiversity targeting microbial and meiofaunal eukaryotes that are the least known component of the deep-sea benthos. We analyzed two 18S rRNA gene regions targeting eukaryotes with a focus on Foraminifera (37F) and metazoans (V1V2), sequenced from 310 surface-sediment samples from the CCZ and other abyssal regions. Our results confirm huge unknown deep-sea biodiversity. Over 60% of benthic foraminiferal and almost a third of eukaryotic operational taxonomic units (OTUs) could not be assigned to a known taxon. Benthic Foraminifera are more common in CCZ samples than metazoans and dominated by clades that are only known from environmental surveys. The most striking results are the uniqueness of CCZ areas, both datasets being characterized by a high number of OTUs exclusive to the CCZ, as well as greater beta diversity compared to other abyssal regions. The alpha diversity in the CCZ is high and correlated with water depth and terrain complexity. Topography was important at a local scale, with communities at CCZ stations located in depressions more diverse and heterogeneous than those located on slopes. This could result from eDNA accumulation, justifying the interim use of eRNA for more accurate biomonitoring surveys. Our descriptions not only support previous findings and consolidate our general understanding of deep-sea ecosystems, but also provide a data resource inviting further taxon-specific and large-scale modeling studies. We foresee that metabarcoding will be useful for deep-sea biomonitoring efforts to consider the diversity of small taxa, but it must be validated based on ground truthing data or experimental studies.

scholarly journals Evaluation of DNA Extraction Methods Developed for Forensic and Ancient DNA Applications Using Bone Samples of Different Age

Genes ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 146
Author(s):  
Catarina Xavier ◽  
Mayra Eduardoff ◽  
Barbara Bertoglio ◽  
Christina Amory ◽  
Cordula Berger ◽  
...  
Keyword(s):  
Dna Extraction ◽  
Ancient Dna ◽  
Extraction Method ◽  
Fragment Size ◽  
Molecular Genetic ◽  
Extraction Methods ◽  
Degraded Dna ◽  
Size Analysis ◽  
Dna Fragments ◽  
Dna Amount

The efficient extraction of DNA from challenging samples, such as bones, is critical for the success of downstream genotyping analysis in molecular genetic disciplines. Even though the ancient DNA community has developed several protocols targeting small DNA fragments that are typically present in decomposed or old specimens, only recently forensic geneticists have started to adopt those protocols. Here, we compare an ancient DNA extraction protocol (Dabney) with a bone extraction method (Loreille) typically used in forensics. Real-time quantitative PCR and forensically representative typing methods including fragment size analysis and sequencing were used to assess protocol performance. We used four bone samples of different age in replicates to study the effects of both extraction methods. Our results confirm Loreille’s overall increased gain of DNA when enough tissue is available and Dabney’s improved efficiency for retrieving shorter DNA fragments that is beneficial when highly degraded DNA is present. The results suggest that the choice of extraction method needs to be based on available sample, degradation state, and targeted genotyping method. We modified the Dabney protocol by pooling parallel lysates prior to purification to study gain and performance in single tube typing assays and found that up to six parallel lysates lead to an almost linear gain of extracted DNA. These data are promising for further forensic investigations as the adapted Dabney protocol combines increased sensitivity for degraded DNA with necessary total DNA amount for forensic applications.

scholarly journals Lung microbiome of stable and exacerbated COPD patients in Tshwane, South Africa

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
T. Goolam Mahomed ◽  
R. P. H. Peters ◽  
M. Allam ◽  
A. Ismail ◽  
S. Mtshali ◽  
...  
Keyword(s):  
Beta Diversity ◽  
Small Sample ◽  
Chronic Obstructive ◽  
Shotgun Metagenomics ◽  
Alpha And Beta Diversity ◽  
Microbiome Composition ◽  
Disease States ◽  
Dna And Rna ◽  
Lung Microbiome ◽  
Copd Patients

AbstractChronic obstructive pulmonary disease (COPD) is characterised by the occurrence of exacerbations triggered by infections. The aim of this study was to determine the composition of the lung microbiome and lung virome in patients with COPD in an African setting and to compare their composition between the stable and exacerbated states. Twenty-four adult COPD patients were recruited from three hospitals. Sputum was collected and bacterial DNA was extracted. Targeted metagenomics was performed to determine the microbiome composition. Viral DNA and RNA were extracted from selected samples followed by cDNA conversion. Shotgun metagenomics sequencing was performed on pooled DNA and RNA. The most abundant phyla across all samples were Firmicutes and Proteobacteria. The following genera were most prevalent: Haemophilus and Streptococcus. There were no considerable differences for alpha and beta diversity measures between the disease states. However, a difference in the abundances between disease states was observed for: (i) Serratia (3% lower abundance in exacerbated state), (ii) Granulicatella (2.2% higher abundance in exacerbated state), (iii) Haemophilus (5.7% higher abundance in exacerbated state) and (iv) Veillonella (2.5% higher abundance in exacerbated state). Virome analysis showed a high abundance of the BeAn 58058 virus, a member of the Poxviridae family, in all six samples (90% to 94%). This study is among the first to report lung microbiome composition in COPD patients from Africa. In this small sample set, no differences in alpha or beta diversity between stable and exacerbated disease state was observed, but an unexpectedly high frequency of BeAn 58058 virus was observed. These observations highlight the need for further research of the lung microbiome of COPD patients in African settings.

Evaluation of biodiversity metrics through environmental DNA metabarcoding compared with visual and capture surveys in river fish community

2019 ◽  
Author(s):  
Hideyuki Doi ◽  
Ryutei Inui ◽  
Shunsuke Matsuoka ◽  
Yoshihisa Akamatsu ◽  
Masuji Goto ◽  
...  
Keyword(s):  
Community Dynamics ◽  
Species Turnover ◽  
Environmental Dna ◽  
List Type ◽  
Visual Capture ◽  
Gamma Diversity ◽  
Community Patterns ◽  
Community Assemblages ◽  
Study Sites ◽  
River Fish

AbstractInformation on alpha (local), beta (between habitats), and gamma (regional) diversity is fundamental to understanding biodiversity as well as the function and stability of community dynamics. The methods like environmental DNA (eDNA) metabarcoding are currently considered useful to investigate biodiversity.We compared the performance of eDNA metabarcoding with visual and capture surveys in estimating alpha/gamma diversity and the variation of the community assemblages of river fish communities, particularly considering community nestedness and turnover.In five rivers across west Japan, with comparing to visual/capture surveys, eDNA metabarcoding detected more species in the study sites, consequently the overall number of species in the region (i.e., gamma diversity) was higher. In particular, the species found by visual/capture surveys were encompassed by those by eDNA metabarcoding.With analyzing the community assemblages between the rivers, we showed the different results between the both methods. While, in the same river, the nestedness and species turnover changing from upstream to downstream did not significantly differ between the both methods. Our results suggest that eDNA metabarcoding may be suitable method, especially for understanding regional community patterns, for fish monitoring in rivers.

ON THE METABOLIC ACTION OF TESTOSTERONE AND RELATED COMPOUNDS

1962 ◽  
Vol 39 (2) ◽  
pp. 223-233 ◽  
Author(s):  
A. Kassenaar ◽  
A. Kouwenhoven ◽  
A. Querido
Keyword(s):  
Dna Content ◽  
Seminal Vesicles ◽  
List Type ◽  
Substitution Therapy ◽  
Kidney Weight ◽  
Dna And Rna ◽  
Rna Content ◽  
Metabolic Action ◽  
Related Compounds ◽  
Rna Concentration

ABSTRACT 1. Changes in nucleic acid composition of the seminal vesicles and kidneys of mice which occur after castration and after substitution therapy with testosterone in castrated animals were studied. 2. It was found that after castration both the DNA and RNA content of the seminal vesicles decreases. The concentration of DNA, however, increases while the RNA concentration in this tissue decreases. 3. These changes are reversed by treatment with testosterone. The rise in RNA content precedes the increase in DNA content of this organ. 4. No changes in DNA content of the kidneys were found either after castration or after treatment with testosterone of castrated mice. The RNA content of this organ changed parallel with the changes in weight. 5. These results strongly suggest that with testosterone treatment, the growth of the seminal vesicles is due to hyperplasia as well as hypertrophy, while the increase in kidney weight is due only to hypertrophy.

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