Uncovering hidden biodiversity in the Cryptophyta: New picoplanktonic clades from clone library studies at the Helgoland time series site in the southern German Bight.

Cryptophyceae are important group in marine phytoplankton, but little is known about the occurrence and distribution of individual species. Recently, with use of molecular probes and microarray technology, it has been shown that species related to Teleaulax spp. or Chroomonas spp. (clades 4 and 6) contributed most to cryptophyceam biomass in the North Sea. The probe for clades 4 and 6 cannot separate them and the single probe recognises members of both clades. Here, we increase the genetic diversity of our investigations of cryptophycean diversity in the North Sea by sequencing 18S rRNA clone libraries made from fractionated water samples to examine specifically the picoplanktonic fraction and to determine whether clade 4 or 6 were the dominant cyrptophytes. We focused on samples from the spring phytoplankton bloom in 2004 because the microarray signals were the strongest at this time. Excluding chimeric sequences, we detected nine cryptophycean OTUs, seven of which fell into the Teleaulax/ Plagioselmis branch, whereas two grouped with Geminigera spp. Our results indicate that these OTUs, affiliated with clade 4, may be an important component of cryptophyte community during spring bloom in the North Sea

POLEMIKA Z MARCJONIZMEM W ORYGENESA KOMENTARZU DO „LISTU ŚWIĘTEGO PAWŁA DO RZYMIAN”

The Polemic with Marcionism in Origenes’ Commentary to the „Letter of St. Paul to the Romans”The article discusses the references to Marcion of Pont as well as to Marcionites contained in Origenes’ commentary to St. Paul’s Letter to the Romans. It was particularly those places where the commentator mentions the heresiarch by name that were taken into consideration; on this basis the views ascribed to the Marcianites are analyzed. Moreover, the author quotes those fragments of the text which though do not mention Marcion directly, yet which contain remarks directed against certain unspecified heresies; the latter may also be regarded as part of Marcion’s teaching. The analyzed fragments of  the commentary point out, above all, to the most important element of Marcion’s heresy , in Origenes’ view, namely to his insistence on the literal interpretation of the Holy Scripture which had led this preacher from Pont to a rejection of the whole of the Old and a considerable part of the New Testament. Also the interpretation of those writings of St. Paul’s which Marcion regards as inspired turns out to be erroneous precisely due to the author’s failure to use an allegorical exegesis. In the conclusions, the author points out that although Origenes presents Marcion’s views, he does not devote a lot of attention to refuting them. Nevertheless, he points out emphatically that in order to assure the correct theological interpretation of the Holy Scripture, one needs to recognize both the literal and the allegorical sense of it

Uncovering hidden biodiversity in the Cryptophyta: Clone library studies at the Helgoland Time Series Site in the Southern German Bight indentifies the cryptophycean clade potentially responsible for the majority of its genetic diversity during the spring bloom.

Cryptophyceae are important group in marine phytoplankton, but little is known about the occurrence and distribution of individual species. Recently, with use of molecular probes and microarray technology, it has been shown that species related to teleaulax spp. or Chroomonas spp. (clades 4 or 6) contributed the most to cryptophycean biomass in the north Sea. for the microarray study, the single probe (clade 4/6) recognizes members of both clades 4 and 6 and thus cannot separate them. Therefore, it was unknown as to whether the cryptophyte community was composed of clade 4, clade 6 or both of them. Here, we addressed this question and increased the genetic diversity of our investigations of cryptophycean diversity in the north Sea by sequencing 18S rRnA clone libraries made from fractionated water samples to examine specifically the picoplanktonic fraction because that fraction was studied in detail in the earlier microarray study. We focused on samples from the spring phytoplankton bloom in 2004 because the microarray signals were the strongest at this time. Excluding chimeric sequences, we detect- ed nine cryptophycean oTUs, seven of which fell into the teleaulax/Plagioselmis branch, whereas two grouped with Geminigera spp. our results indicate that these oTUs, affiliated with clade 4, may be an important component of cryptophyte community during spring bloom in the north Se

Seasonality of occurrence and recruitment of Arctic marine benthic invertebrate larvae in relation to environmental variables

The Arctic system is one of the regions most influenced by ongoing global climate change, but there are still critical gaps in our knowledge regarding a substantial number of biological processes. This is especially true for processes taking place during the Arctic winter but also for seasonal processes, such as the dynamics of intra-annual meroplankton occurrence. Here, we report on a 1-year study of meroplankton seasonal variability from a fjordic system in the Arctic Archipelago of Svalbard. The study combines an examination of phytoplankton, zooplankton, and hard bottom benthic settlement with measurements of environmental parameters (e.g., water temperature, particulate organic matter, and dissolved organic carbon). Samples were taken on a bi-weekly or monthly basis, and a total of 11 taxa representing six phyla of meroplankton were recorded over a 1-year period from January to December 2007. The occurrence of benthic larvae varied between the seasons, reaching a maximum in both abundance and taxon richness in late spring through early summer. Meroplanktonic larvae were absent in winter. However, settlement of benthic organisms was also recorded during the winter months (February and March), which indicates individual trade-offs related to timing of reproduction and competition. In addition, it suggests that these larvae are not relying on higher summer nutrient concentrations, but instead are dependent on alternative food sources. In parallel with meroplankton abundance, all other measured parameters, both biological (e.g., phyto- and zooplankton abundance and diversity) and physical (e.g., particulate organic matter), exhibited seasonal variability with peaks in the warmer months of the year

Common Presence of Phototrophic Gemmatimonadota in Temperate Freshwater Lakes

Members of the bacterial phylum Gemmatimonadota are ubiquitous in most natural environments and represent one of the top 10 most abundant bacterial phyla in soil. Sequences affiliated with Gemmatimonadota were also reported from diverse aquatic habitats; however, it remains unknown whether they are native organisms or represent bacteria passively transported from sediment or soil. To address this question, we analyzed metagenomes constructed from five freshwater lakes in central Europe. Based on the 16S rRNA gene frequency, Gemmatimonadota represented from 0.02 to 0.6% of all bacteria in the epilimnion and between 0.1 and 1% in the hypolimnion. These proportions were independently confirmed using catalyzed reporter deposition-fluorescence in situ hybridization (CARD-FISH). Some cells in the epilimnion were attached to diatoms (Fragilaria sp.) or cyanobacteria (Microcystis sp.), which suggests a close association with phytoplankton. In addition, we reconstructed 45 metagenome-assembled genomes (MAGs) related to Gemmatimonadota. They represent several novel lineages, which persist in the studied lakes during the seasons. Three lineages contained photosynthesis gene clusters. One of these lineages was related to Gemmatimonas phototrophica and represented the majority of Gemmatimonadota retrieved from the lakes’ epilimnion. The other two lineages came from hypolimnion and probably represented novel photoheterotrophic genera. None of these phototrophic MAGs contained genes for carbon fixation. Since most of the identified MAGs were present during the whole year and cells associated with phytoplankton were observed, we conclude that they represent truly limnic Gemmatimonadota distinct from the previously described species isolated from soils or sediments

Status and trends in the structure of Arctic benthic food webs

Ongoing climate warming is causing a dramatic loss of sea ice in the Arctic Ocean, and it is projected that the Arctic Ocean will become seasonally ice-free by 2040. Many studies of local Arctic food webs now exist, and with this review paper we aim to synthesize these into a large-scale assessment of the current status of knowledge on the structure of various Arctic marine food webs and their response to climate change, and to sea-ice retreat in particular. Key drivers of ecosystem change and potential consequences for ecosystem functioning and Arctic marine food webs are identified along the sea-ice gradient, with special emphasis on the following regions: seasonally ice-free Barents and Chukchi seas, loose ice pack zone of the Polar Front and Marginal Ice Zone, and permanently sea-ice covered High Arctic. Finally, we identify knowledge gaps in different Arctic marine food webs and provide recommendations for future studie

Enrichment of Omnivorous Cercozoan Nanoflagellates from Coastal Baltic Sea Waters

Free-living nano-sized flagellates are important bacterivores in aquatic habitats. However, some slightly larger forms can also be omnivorous, i.e., forage upon both bacterial and eukaryotic resources. This hitherto largely ignored feeding mode may have pronounced implications for the interpretation of experiments about protistan bacterivory. We followed the response of an uncultured group of omnivorous cercozoan nanoflagellates from the Novel Clade 2 (Cerc_BAL02) to experimental food web manipulation in samples from the Gulf of Gdańsk (Southern Baltic Sea). Seawater was either prefiltered through 5 µm filters to exclude larger predators of nanoflagellates (F-treatment), or prefiltered and subsequently 1∶10 diluted with sterile seawater (F+D-treatment) to stimulate the growth of both, flagellates and bacteria. Initially, Cerc_BAL02 were rapidly enriched under both conditions. They foraged on both, eukaryotic prey and bacteria, and were highly competitive at low concentrations of food. However, these omnivores were later only successful in the F+D treatment, where they eventually represented almost one fifth of all aplastidic nanoflagellates. By contrast, their numbers stagnated in the F-treatment, possibly due to top-down control by a concomitant bloom of other, unidentified flagellates. In analogy with observations about the enrichment of opportunistically growing bacteria in comparable experimental setups we suggest that the low numbers of omnivorous Cerc_Bal02 flagellates in waters of the Gulf of Gdańsk might also be related to their vulnerability to grazing pressure