Sammendrag
The enormous contrasts in light and seasonal productivity in high-latitude pelagic marine environments bespeaks an environment in which microorganisms must adapt to extremes in light and productivity. As important regulators of host diversity and nutrient recycling, viruses are critical components of the marine environment and the marine food web. The interdependence of viruses on the hosts they infect suggests that virus assemblages in high-latitude marine biomes may vary in step with season- and depth-driven variation in host populations. Furthermore, the extreme nature of the Arctic biome may house previously undescribed viral diversity. In order to survey of Arctic marine virus assemblages, we conducted research cruises to the west and north of Svalbard across one calendar year, sampling at depths from surface to 1000m. We extracted total nucleic acids from virus concentrates prepared from 50L of tangential flow-concentrated 0.45 or 0.2 µm-filtered seawater fractions. RNA and ssDNA virus genomes were converted to dsDNA using a combination of reverse transcription and second-strand synthesis. Total libraries, potentially representing all combinations of single-stranded or double-stranded and DNA or RNA virus genomes, were then amplified using random PCR and sequenced using Illumina MiSeq v3 PE300. Virus metagenomes were analyzed using both MG-RAST and by manual quality-trimming and assembly followed by analysis using the MetaVir2 platform. Preliminary taxonomic analysis of virus metagenomes suggests a high diversity of virus genome types, including a predominance of dsDNA and ssDNA genomes and a lesser contribution from RNA virus genomes. We observed large functional diversity in metagenomes, with an indication of depth-dependence on functional repertoire. Assembly of virus metagenomes resulted in the generation of almost entirely contigs
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