scholarly journals An Optimized Metabarcoding Method for Mimiviridae

2020 ◽  
Vol 8 (4) ◽  
pp. 506
Author(s):  
Florian Prodinger ◽  
Hisashi Endo ◽  
Yasuhiro Gotoh ◽  
Yanze Li ◽  
Daichi Morimoto ◽  
...  
Keyword(s):  
Dna Polymerase ◽  
Environmental Samples ◽  
Environmental Dna ◽  
Degenerate Primer ◽  
Polymerase Gene ◽  
Operational Taxonomic Units ◽  
Ecological Relevance ◽  
Seawater Samples ◽  
Multiple Samples ◽  
Pcr Conditions

Mimiviridae is a group of viruses with large genomes and virions. Ecological relevance of Mimiviridae in marine environments has been increasingly recognized through the discoveries of novel isolates and metagenomic studies. To facilitate ecological profiling of Mimiviridae, we previously proposed a meta-barcoding approach based on 82 degenerate primer pairs (i.e., MEGAPRIMER) targeting the DNA polymerase gene of Mimiviridae. The method detected a larger number of operational taxonomic units (OTUs) in environmental samples than previous methods. However, it required large quantities of DNA and was laborious due to the use of individual primer pairs. Here, we examined coastal seawater samples using varying PCR conditions and purification protocols to streamline the MEGAPRIMER method. Mixing primer pairs in “cocktails” reduced the required amount of environmental DNA by 90%, while reproducing the results obtained by the original protocol. We compared the results obtained by the meta-barcoding approach with quantifications using qPCR for selected OTUs. This revealed possible amplification biases among different OTUs, but the frequency profiles for individual OTUs across multiple samples were similar to those obtained by qPCR. We anticipate that the newly developed MEGAPRIMER protocols will be useful for ecological investigation of Mimiviridae in a larger set of environmental samples.

scholarly journals Seeing through sedimented waters: environmental DNA reduces the phantom diversity of sharks and rays in turbid marine habitats

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Yin Cheong Aden Ip ◽  
Jia Jin Marc Chang ◽  
Kelvin K. P. Lim ◽  
Zeehan Jaafar ◽  
Benjamin J. Wainwright ◽  
...  
Keyword(s):  
High Throughput Sequencing ◽  
Environmental Dna ◽  
Historical Collections ◽  
Operational Taxonomic Units ◽  
Marine Habitats ◽  
The Pacific ◽  
Elasmobranch Species ◽  
Reef Sharks ◽  
Seawater Samples ◽  
Diversity Estimates

Abstract Background Sharks and rays are some of the most threatened marine taxa due to the high levels of bycatch and significant demand for meat and fin-related products in many Asian communities. At least 25% of shark and ray species are considered to be threatened with extinction. In particular, the density of reef sharks in the Pacific has declined to 3–10% of pre-human levels. Elasmobranchs are thought to be sparse in highly urbanised and turbid environments. Low visibility coupled with the highly elusive behaviour of sharks and rays pose a challenge to diversity estimation and biomonitoring efforts as sightings are limited to chance encounters or from carcasses ensnared in nets. Here we utilised an eDNA metabarcoding approach to enhance the precision of elasmobranch diversity estimates in urbanised marine environments. Results We applied eDNA metabarcoding on seawater samples to detect elasmobranch species in the hyper-urbanised waters off Singapore. Two genes—vertebrate 12S and elasmobranch COI—were targeted and amplicons subjected to Illumina high-throughput sequencing. With a total of 84 water samples collected from nine localities, we found 47 shark and ray molecular operational taxonomic units, of which 16 had species-level identities. When data were compared against historical collections and contemporary sightings, eDNA detected 14 locally known species as well as two potential new records. Conclusions Local elasmobranch richness uncovered by eDNA is greater than the seven species sighted over the last two decades, thereby reducing phantom diversity. Our findings demonstrate that eDNA metabarcoding is effective in detecting shark and ray species despite the challenges posed by the physical environment, granting a more consistent approach to monitor these highly elusive and threatened species.

scholarly journals Accumulation curves of environmental DNA sequences predict coastal fish diversity in the coral triangle

2020 ◽  
Vol 287 (1930) ◽  
pp. 20200248 ◽  
Author(s):  
Jean-Baptiste Juhel ◽  
Rizkie S. Utama ◽  
Virginie Marques ◽  
Indra B. Vimono ◽  
Hagi Yulia Sugeha ◽  
...  
Keyword(s):  
Dna Sequences ◽  
Environmental Dna ◽  
Reference Database ◽  
Fish Diversity ◽  
Sampling Effort ◽  
Coral Triangle ◽  
Model Framework ◽  
Operational Taxonomic Units ◽  
Accumulation Curves ◽  
Seawater Samples

Environmental DNA (eDNA) has the potential to provide more comprehensive biodiversity assessments, particularly for vertebrates in species-rich regions. However, this method requires the completeness of a reference database (i.e. a list of DNA sequences attached to each species), which is not currently achieved for many taxa and ecosystems. As an alternative, a range of operational taxonomic units (OTUs) can be extracted from eDNA metabarcoding. However, the extent to which the diversity of OTUs provided by a limited eDNA sampling effort can predict regional species diversity is unknown. Here, by modelling OTU accumulation curves of eDNA seawater samples across the Coral Triangle, we obtained an asymptote reaching 1531 fish OTUs, while 1611 fish species are recorded in the region. We also accurately predict ( R ² = 0.92) the distribution of species richness among fish families from OTU-based asymptotes. Thus, the multi-model framework of OTU accumulation curves extends the use of eDNA metabarcoding in ecology, biogeography and conservation.

scholarly journals Genetic evidence for two protein domains and a potential new activity in bacteriophage T4 DNA polymerase.

Genetics ◽  
1990 ◽  
Vol 124 (2) ◽  
pp. 213-220 ◽  
Author(s):  
L J Reha-Krantz
Keyword(s):  
Dna Polymerase ◽  
Bacteriophage T4 ◽  
Rnase H ◽  
Ribonuclease H ◽  
Temperature Sensitive ◽  
Polymerase Gene ◽  
Dna Polymerase I ◽  
E Coli ◽  
Intragenic Complementation ◽  
Polymerase I

Abstract Intragenic complementation was detected within the bacteriophage T4 DNA polymerase gene. Complementation was observed between specific amino (N)-terminal, temperature-sensitive (ts) mutator mutants and more carboxy (C)-terminal mutants lacking DNA polymerase polymerizing functions. Protein sequences surrounding N-terminal mutation sites are similar to sequences found in Escherichia coli ribonuclease H (RNase H) and in the 5'----3' exonuclease domain of E. coli DNA polymerase I. These observations suggest that T4 DNA polymerase, like E. coli DNA polymerase I, contains a discrete N-terminal domain.

Exploring the plant environmental DNA diversity in soil from two sites on Deception Island (Antarctica, South Shetland Islands) using metabarcoding

2021 ◽  
pp. 1-10
Author(s):  
Micheline Carvalho-Silva ◽  
Luiz Henrique Rosa ◽  
Otávio H.B. Pinto ◽  
Thamar Holanda Da Silva ◽  
Diego Knop Henriques ◽  
...  
Keyword(s):  
High Throughput Sequencing ◽  
Crater Lake ◽  
Environmental Dna ◽  
Food Sources ◽  
South Shetland Islands ◽  
Deception Island ◽  
Shetland Islands ◽  
Operational Taxonomic Units ◽  
First Time ◽  
Impacted Site

Abstract The few Antarctic studies to date to have applied metabarcoding in Antarctica have primarily focused on microorganisms. In this study, for the first time, we apply high-throughput sequencing of environmental DNA to investigate the diversity of Embryophyta (Viridiplantae) DNA present in soil samples from two contrasting locations on Deception Island. The first was a relatively undisturbed site within an Antarctic Specially Protected Area at Crater Lake, and the second was a heavily human-impacted site in Whalers Bay. In samples obtained at Crater Lake, 84% of DNA reads represented fungi, 14% represented Chlorophyta and 2% represented Streptophyta, while at Whalers Bay, 79% of reads represented fungi, 20% represented Chlorophyta and < 1% represented Streptophyta, with ~1% of reads being unassigned. Among the Embryophyta we found 16 plant operational taxonomic units from three Divisions, including one Marchantiophyta, eight Bryophyta and seven Magnoliophyta. Sequences of six taxa were detected at both sampling sites, eight only at Whalers Bay and two only at Crater Lake. All of the Magnoliophyta sequences (flowering plants) represent species that are exotic to Antarctica, with most being plausibly linked to human food sources originating from local national research operator and tourism facilities.

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