Azaspiracid-59 accumulation and transformation in mussels (Mytilus edulis) after feeding with Azadinium poporum (Dinophyceae).

Azaspiracid-59 (AZA-59) was detected in plankton in coastal waters of the Pacific Northwest USA. Given that bivalves metabolize and transform accumulated phycotoxins, a strain of Azadinium poporum isolated from the coast of Washington State that is a known producer of AZA-59 was used in a controlled feeding experiment with mussels (Mytilus edulis) to assess AZA-59 accumulation rates and transformation into shellfish metabolites. Mussels started feeding immediately after the addition of A.

Including the liver in the visceral allograft: Impact on donor-specific anti-HLA antibodies and long-term outcomes.

Humoral immunity emerges as a risk factor for graft failure after visceral transplantation (VTx) and development of donor-specific anti-HLA antibodies (DSAs) has been linked with poor outcomes. In most cases, a simultaneous liver transplant can be safely performed in sensitized patients with DSA and appears protective against lymphocytotoxic antibodies. We investigated the incidence of acute (AR) and chronic rejection (CR) in 32 VTx without any B cell-depleting pre-treatment (6 isolated intestinal transplants (IT) and 26 liver-containing, multivisceral transplants (MVT) and assessed the presence of donor-specific antibodies (DSA) pre- and post-transplantation.

Molecular responses to ocean acidification in an Antarctic bivalve and an ascidian.

Southern Ocean organisms are considered particularly vulnerable to Ocean acidification (OA), as they inhabit cold waters where calcite-aragonite saturation states are naturally low. It is also generally assumed that OA would affect calcifying animals more than non-calcifying animals. In this context, we aimed to study the impact of reduced pH on both types of species: the ascidian Cnemidocarpa verrucosa sp.

Mitochondrial Heteroplasmy and PCR Amplification Bias Lead to Wrong Species Delimitation with High Confidence in the South American and Antarctic Marine Bivalve Species Complex.

The species delimitation of the marine bivalve species complex in South America and Antarctica is complicated by mitochondrial heteroplasmy and amplification bias in molecular barcoding. In this study, we compare different data sources (mitochondrial cytochrome c oxidase subunit I () sequences; nuclear and mitochondrial SNPs). Whilst all the data suggest that populations on either side of the Drake Passage belong to different species, the picture is less clear within Antarctic populations, which harbor three distinct mitochondrial lineages (p-dist ≈ 6%) that coexist in populations and in a subset of individuals with heteroplasmy.

A molecular perspective on the invasibility of the southern ocean benthos: The impact of hypoxia and temperature on gene expression in South American and Antarctic bivalves.

When an organism makes a long-distance transition to a new habitat, the associated environmental change is often marked and requires physiological plasticity of larvae, juveniles, or other migrant stages. Exposing shallow-water marine bivalves () from southern South America (SSA) and the West Antarctic Peninsula (WAP) to changes in temperature and oxygen availability, we investigated changes in gene expression in a simulated colonization experiment of the shores of a new continent after crossing of the Drake Passage, and in a warming scenario in the WAP. Bivalves from SSA were cooled from 7°C () to 4°C and 2°C (future warmed WAP conditions), WAP bivalves were warmed from 1.

Photodegradation of a bacterial pigment and resulting hydrogen peroxide release enable coral settlement.

The global degradation of coral reefs is steadily increasing with ongoing climate change. Yet coral larvae settlement, a key mechanism of coral population rejuvenation and recovery, is largely understudied. Here, we show how the lipophilic, settlement-inducing bacterial pigment cycloprodigiosin (CYPRO) is actively harvested and subsequently enriched along the ectoderm of larvae of the scleractinian coral Leptastrea purpura.

Molecular responses of a key Antarctic species to sedimentation due to rapid climate change.

Rapid regional warming causing glacial retreat and melting of ice caps in Antarctica leads benthic filter-feeders to be exposed to periods of food shortage and high respiratory impairment as a consequence of seasonal sediment discharge in the West Antarctic Peninsula coastal areas. The molecular physiological response and its fine-tuning allow species to survive acute environmental stress and are thus a prerequisite to longer-term adaptation to changing environments. Under experimental conditions, we analyzed here the metabolic response to changes in suspended sediment concentrations, through transcriptome sequencing and enzymatic measurements in a highly abundant Antarctic ascidian.

Sustainable conversion of biomass to rationally designed lithium-ion battery graphite.

The carbon net negative conversion of bio-char, the low value byproduct of pyrolysis bio-oil production from biomass, to high value, very high purity, highly crystalline flake graphite agglomerates with rationally designed shape and size tailored for lithium-ion battery energy storage material is reported. The process is highly efficient, 0.41 g/Wh; the energy content of its co-product of the process, bio-oil, exceeds that needed to power the process.

Appropriate relaxation of non-pharmaceutical interventions minimizes the risk of a resurgence in SARS-CoV-2 infections in spite of the Delta variant.

We analyze the relaxation of non-pharmaceutical interventions (NPIs) under an increasing number of vaccinations in Germany. For the spread of SARS-CoV-2 we employ a SIR-type model that accounts for age-dependence and includes realistic contact patterns between age groups. The implementation of NPIs occurs on changed contact patterns, improved isolation, or reduced infectiousness when, e.

Regional opening strategies with commuter testing and containment of new SARS-CoV-2 variants in Germany.

Background: Despite the vaccination process in Germany, a large share of the population is still susceptible to SARS-CoV-2. In addition, we face the spread of novel variants. Until we overcome the pandemic, reasonable mitigation and opening strategies are crucial to balance public health and economic interests.

Presence of male mitochondria in somatic tissues and their functional importance at the whole animal level in the marine bivalve Arctica islandica.

Metazoans normally possess a single lineage of mitochondria inherited from the mother (♀-type mitochondria) while paternal mitochondria are absent or eliminated in fertilized eggs. In doubly uniparental inheritance (DUI), which is specific to the bivalve clade including the ocean quahog, Arctica islandica, ♂-type mitochondria are retained in male gonads and, in a few species, small proportions of ♂-type mitochondria co-exist with ♀-type in somatic tissues. To the best of our knowledge, we report, for the first time in metazoan, the natural occurrence of male and female individuals with exclusively ♂-type mitochondria in somatic tissues of the bivalve A.

In Vitro Effects of Paralytic Shellfish Toxins and Lytic Extracellular Compounds Produced by Strains on Hemocyte Integrity and Function in .

Harmful effects caused by the exposure to paralytic shellfish toxins (PSTs) and bioactive extracellular compounds (BECs) on bivalves are frequently difficult to attribute to one or the other compound group. We evaluate and compare the distinct effects of PSTs extracted from (Alex5) cells and extracellular lytic compounds (LCs) produced by (NX-57-08) on hemocytes. We used a 4 h dose-response in vitro approach and analyzed how these effects correlate with those observed in a previous in vivo feeding assay.

Molecular mechanisms underlying responses of the Antarctic coral Malacobelemnon daytoni to ocean acidification.

Benthic organisms of the Southern Ocean are particularly vulnerable to ocean acidification (OA), as they inhabit cold waters where calcite-aragonite saturation states are naturally low. OA most strongly affects animals with calcium carbonate skeletons or shells, such as corals and mollusks. We exposed the abundant cold-water coral Malacobelemnon daytoni from an Antarctic fjord to low pH seawater (LpH) (7.

Assessment of effective mitigation and prediction of the spread of SARS-CoV-2 in Germany using demographic information and spatial resolution.

Non-pharmaceutical interventions (NPIs) are important to mitigate the spread of infectious diseases as long as no vaccination or outstanding medical treatments are available. We assess the effectiveness of the sets of non-pharmaceutical interventions that were in place during the course of the Coronavirus disease 2019 (Covid-19) pandemic in Germany. Our results are based on hybrid models, combining SIR-type models on local scales with spatial resolution.

Antarctic ascidians under increasing sedimentation: Physiological thresholds and ecosystem hysteresis.

Glacier melting sediment inputs affect coastal ecosystems on the Antarctic Peninsula. In Potter Cove (South Shetland Islands, Antarctica), the shift from an "ascidian dominated" to a "mixed" assemblage has been linked to sedimentation. However, in recently described newly ice-free areas ascidians became dominant in spite of total suspended particulate matter (TSPM) concentrations, which are the highest measured in Potter Cove.

Nitric oxide mediates metabolic functions in the bivalve Arctica islandica under hypoxia.

The free radical nitric oxide (NO) is a powerful metabolic regulator in vertebrates and invertebrates. At cellular concentrations in the nanomolar range, and simultaneously reduced internal oxygen partial pressures (pO2), NO completely inhibits cytochrome-c-oxidase (CytOx) activity and hence mitochondrial- and whole-tissue respiration. The infaunal clam Arctica islandica regulates pO2 of hemolymph and mantle cavity water to mean values of <5 kPa, even in a completely oxygen-saturated environment of 21 kPa.

Ink synthesis and inkjet printing of electrostatically stabilized multilayer graphene nanoshells.

Hypothesis: Most functional inkjet inks are sterically stabilized nanoparticle dispersions that require a post-printing-process to remove stabilizing materials and gain functionality. This post-process limits material selection and increases fabrication time and complexity for printed devices. By optimizing the electrostatic stability of a carbon nanomaterial dispersed in water or ethylene glycol via pH adjustment, a stable and printable ink should be attainable without a steric stabilizing material and hence the post-process may be avoided.

Mitochondrial Traits Previously Associated With Species Maximum Lifespan Do Not Correlate With Longevity Across Populations of the Bivalve .

The mitochondrial oxidative stress theory of aging posits that membrane susceptibility to peroxidation and the organization of the electron transport system (ETS) linked with reactive oxygen species (ROS) generation are two main drivers of lifespan. While a clear correlation has been established from species comparative studies, the significance of these characteristics as potential modulators of lifespan divergences among populations of individual species is still to be tested. The bivalve , the longest-lived non-colonial animal with a record lifespan of 507 years, possesses a lower mitochondrial peroxidation index (PI) and reduced HO efflux linked to complexes I and III activities than related species.

Hypoxically Induced Nitric Oxide: Potential Role as a Vasodilator in Gills.

Intertidal experience rapid transgression to hypoxia when they close their valves during low tide. This induces a physiological stress response aiming to stabilize tissue perfusion against declining oxygen partial pressure in shell water. We hypothesized that nitric oxide (NO) accumulation supports blood vessel opening in hypoxia and used live imaging techniques to measure NO and superoxide anion ( ) formation in hypoxia-exposed gill filaments.

Separate and combined effects of neurotoxic and lytic compounds of Alexandrium strains on Mytilus edulis feeding activity and hemocyte function.

Multiple toxic and bioactive compounds produced by Alexandrium spp. cause adverse effects on bivalves, but these effects are frequently difficult to attribute to a single compound class. To disentangle the effect of neurotoxic vs lytic secondary metabolites, we exposed blue mussels to either a paralytic shellfish toxin (PST) producing Alexandrium spp.

Benthic meltwater fjord habitats formed by rapid glacier recession on King George Island, Antarctica.

The coasts of the West Antarctic Peninsula are strongly influenced by glacier meltwater discharge. The spatial structure and biogeochemical composition of inshore habitats are shaped by large quantities of terrigenous particulate material deposited in the vicinity of the coast, which impacts the pelagic and benthic ecosystems. We used a multitude of geochemical and environmental variables to identify the radius extension of the meltwater impact from the Fourcade Glacier into the fjord system of Potter Cove, King George Island.

Inter-decadal variability of phytoplankton biomass along the coastal West Antarctic Peninsula.

The West Antarctic Peninsula (WAP) is a climatically sensitive region where periods of strong warming have caused significant changes in the marine ecosystem and food-web processes. Tight coupling between phytoplankton and higher trophic levels implies that the coastal WAP is a bottom-up controlled system, where changes in phytoplankton dynamics may largely impact other food-web components. Here, we analysed the inter-decadal time series of year-round chlorophyll- (Chl) collected from three stations along the coastal WAP: Carlini Station at Potter Cove (PC) on King George Island, Palmer Station on Anvers Island and Rothera Station on Adelaide Island.

Anatomy of a glacial meltwater discharge event in an Antarctic cove.

Glacial meltwater discharge from Antarctica is a key influence on the marine environment, impacting ocean circulation, sea level and productivity of the pelagic and benthic ecosystems. The responses elicited depend strongly on the characteristics of the meltwater releases, including timing, spatial structure and geochemical composition. Here we use isotopic tracers to reveal the time-varying pattern of meltwater during a discharge event from the Fourcade Glacier into Potter Cove, northern Antarctic Peninsula.