Spring phytoplankton communities of the Labrador Sea (2005–2014): pigment signatures, photophysiology and elemental ratios

The Labrador Sea is an ideal region to study the biogeographical, physiological, and biogeochemical implications of phytoplankton community composition due to sharp transitions between distinct water masses across its shelves and central basin. We have investigated the multi-year (2005–2014) distributions of late spring and early summer (May to June) phytoplankton communities in the various hydrographic settings of the Labrador Sea. Our analysis is based on pigment markers (using CHEMTAX analysis), and photophysiological and biogeochemical characteristics associated with each phytoplankton community. Diatoms were the most abundant group, blooming first in shallow mixed layers of haline-stratified Arctic shelf waters. Along with diatoms, chlorophytes co-dominated at the western end of the section (particularly in the polar waters of the Labrador Current (LC)), whilst Phaeocystis co-dominated in the east (modified polar waters of the West Greenland Current (WGC)). Pre-bloom conditions occurred in deeper mixed layers of the central Labrador Sea in May, where a mixed assemblage of flagellates (dinoflagellates, prasinophytes, prymnesiophytes, particularly coccolithophores, and chrysophytes/pelagophytes) occurred in low-chlorophyll areas, succeeding to blooms of diatoms and dinoflagellates in thermally stratified Atlantic waters in June. Light-saturated photosynthetic rates and saturation irradiance levels were highest at stations where diatoms were the dominant phytoplankton group ( >  70 % of total chlorophyll a), as opposed to stations where flagellates were more abundant (from 40 up to 70 % of total chlorophyll a). Phytoplankton communities from the WGC (Phaeocystis and diatoms) had lower light-limited photosynthetic rates, with little evidence of photoinhibition, indicating greater tolerance to a high light environment. By contrast, communities from the central Labrador Sea (dinoflagellates and diatoms), which bloomed later in the season (June), appeared to be more sensitive to high light levels. Ratios of accessory pigments (AP) to total chlorophyll a (TChl a) varied according to phytoplankton community composition, with polar phytoplankton (cold-water related) having lower AP  :  TChl a. Polar waters (LC and WGC) also had higher and more variable particulate organic carbon (POC) to particulate organic nitrogen (PON) ratios, suggesting the influence of detritus from freshwater input, derived from riverine, glacial, and/or sea ice meltwater. Long-term observational shifts in phytoplankton communities were not assessed in this study due to the short temporal frame (May to June) of the data. Nevertheless, these results add to our current understanding of phytoplankton group distribution, as well as an evaluation of the biogeochemical role (in terms of C  :  N ratios) of spring phytoplankton communities in the Labrador Sea, which will assist our understanding of potential long-term responses of phytoplankton communities in high-latitude oceans to a changing climate

Biogeographical patterns and environmental controls of phytoplankton communities from contrasting hydrographical zones of the Labrador Sea

The Labrador Sea is an important oceanic sink for atmospheric CO2 because of intensive convective mixing during winter and extensive phytoplankton blooms that occur during spring and summer. Therefore, a broad-scale investigation of the responses of phytoplankton community composition to environmental forcing is essential for understanding planktonic food-web organisation and biogeochemical functioning in the Labrador Sea. Here, we investigated the phytoplankton community structure (>4 μm) from near surface blooms (1.2 mg chla m−3) occurred on and near the shelves in May and in offshore waters of the central Labrador Sea in June due to haline- and thermal-stratification, respectively. Sea ice-related (Fragilariopsis cylindrus and F. oceanica) and Arctic diatoms (Fossula arctica, Bacterosira bathyomphala and Thalassiosira hyalina) dominated the relatively cold (<0 °C) and fresh (salinity < 33) waters over the Labrador shelf (e.g., on the southwestern side of the Labrador Sea), where sea-ice melt and Arctic outflow predominates. On the northeastern side of the Labrador Sea, intense blooms of the colonial prymnesiophyte Phaeocystis pouchetii and diatoms, such as Thalassiosira nordenskioeldii, Pseudo-nitzschia granii and Chaetoceros socialis, occurred in the lower nutrient waters (nitrate < 3.6 μM) of the West Greenland Current. The central Labrador Sea bloom occurred later in the season (June) and was dominated by Atlantic diatoms, such as Ephemera planamembranacea and Fragilariopsis atlantica. The data presented here demonstrate that the Labrador Sea spring and early summer blooms are composed of contrasting phytoplankton communities, for which taxonomic segregation appears to be controlled by the physical and biogeochemical characteristics of the dominant water masses

Plankton community respiration and bacterial metabolism in a North Atlantic Shelf Sea during spring bloom development (April 2015)

Spring phytoplankton blooms are important events in Shelf Sea pelagic systems as the increase in carbon production results in increased food availability for higher trophic levels and the export of carbon to deeper waters and the sea-floor. It is usually accepted that the increase in phytoplankton abundance and production is followed by an increase in plankton respiration. However, this expectation is derived from field studies with a low temporal sampling resolution (5–15 days). In this study we have measured the time course of plankton abundance, gross primary production, plankton community respiration, respiration of the plankton size classes (>0.8 µm and 0.2–0.8 µm) and bacterial production at ≤5 day intervals during April 2015 in order to examine the phasing of plankton autotrophic and heterotrophic processes. Euphotic depth-integrated plankton community respiration increased five-fold (from 22 ± 4 mmol O2 m−2 d−1 on 4th April to 119 ± 4 mmol O2 m−2 d−1 on 15th April) at the same time as gross primary production also increased five-fold, (from 114 ± 5 to 613 ± 28 mmol C m−2 d−1). Bacterial production began to increase during the development of the bloom, but did not reach its maximum until 5 days after the peak in primary production and plankton respiration. The increase in plankton community respiration was driven by an increase in the respiration attributable to the >0.8 µm size fraction of the plankton community (which would include phytoplankton, microzooplankton and particle attached bacteria). Euphotic depth-integrated respiration of the 0.2–0.8 µm size fraction (predominantly free living bacteria) decreased and then remained relatively constant (16 ± 3 – 11 ± 1 mmol O2 m−2 d−1) between the first day of sampling (4th April) and the days following the peak in chlorophyll-a (20th and 25th April). Recent locally synthesized organic carbon was more than sufficient to fulfil the bacterial carbon requirement in the euphotic zone during this productive period. Changes in bacterial growth efficiencies (BGE, the ratio of bacterial production to bacterial carbon demand) were driven by changes in bacterial production rates increasing from 0.8 µm during the development of the spring bloom, followed 5 days later by a peak in bacterial production. In addition, the size fractionated respiration rates and high growth efficiencies suggest that free living bacteria are not the major producers of CO2 before, during and a few days after this shelf sea spring phytoplankton bloom.The Leverhulme Trust | Ref. RPG-2017-089UK Natural Environment Research Council (NERC) | Ref. NE/K00168X/1UK Natural Environment Research Council (NERC) | Ref. NE/ K001884/1UK Natural Environment Research Council (NERC) | Ref. NE/K002058/1UK Natural Environment Research Council (NERC) | Ref. NE/K001701/

DIE BIOETHIK UND ANTHROPOLOGIE

Budući da je i bioetika, kako je već naznačeno i u njezinu imenu, posebna, specijalna etika (sadržana i u koncepciji bioetike kao nove, transdisciplinarne znanosti), prvo je rečeno ono osnovno o etici kao disciplini praktičke filozofije, da bi tako postao razgovjetniji i smisao, zadaća i mogućnosti bioetike kao primijenjene etike na područje života općenito, prvenstveno na čovjekov život i zdravlje. Kako je etika kao refleksija o ispravnom i dobrom ljudskom djelovanju bitno povezana s antropologijom kao filozofijskim i znanstvenim promišljanjem naravi, položaja u svijetu i biti čovjekova bića uopće (prirodnoga, društvenoga i duhovnog), to je u drugom dijelu ovoga konspekta pokazana i »pupčana« sveza bioetike s antropologijom, s posebnim obzirom na suvremene ekološke uvjete života, tj. na prijeteću globalnu i strukturalnu ekološku krizu.Since bioethics, as the name itself indicates, is a special kind of ethics (contained in the concept of bioethics as a new, transdisciplinary science), in the beginning, the basic thing about ethics as a discipline of practical philosophy is said, to make, therefore, more comprehensible the sense, task and possibilities of bioethics as applied ethics in the field of life in general, first of all, in human\u27s life and health. And since ethics as a reflection on right and good human activity is essentially connected with anthropology as philosophical and scientific reflexion on nature, on the position in the world and on the essence of human being in general (natural, social and spiritual) , thus, in the second part of this conspectus, the "umbilical" connection between bioethics and anthropology has been shown, with the special regard to contemporary ecological conditions of life, i.e. to the threatening global and ecological crisis.Da auch die Bioethik wie schon aus ihrem Namen hervorgeht eine besondere spezielle Ethik ist (das ist auch in der Konzeption der Bioethik als einer neuen transdisziplinaren Wisenschaft enthalten), wurde zuerst das Grundlegende über Ethik als einer Disziplin der praktischen Philosophie gesagt, damit so auch der Sinn deutlich wird, die Aufgabe und die Möglichkeiten der Bioethik als einer auf dem Gebiet des Lebens allgemein angewandten Ethik, vor allem angewandt auf das menschliche Leben und Gesundheit. Da die Ethik als eine Reflexion über die gute und richtige Wirkung des Menschen im Wesentlichen mit der Anthropologie als philosophische und wissenschaftliche Überlegung der menschlichen Natur verbunden ist, mit der Stellung in der Welt und dem Kern des menschlichen Wesens (natürlichem, gesellschaftlichem und geistigem), so ist im zweiten Teil dieses Konspekts die "Nabelschnurr" — Verbindung der Bioethik mit der Anthropologie dargelegt, und daß mit besonderer Berücksichtigung der heutigen ökologischen Umweltbediengungen., d.h. der droheneden globalen und strukturalen ökologischen Krise

Diatom Biogeography From the Labrador Sea Revealed Through a Trait-Based Approach

Diatoms are a keystone algal group, with diverse cell morphology and a global distribution. The biogeography of morphological, functional, and life-history traits of marine diatoms were investigated in Arctic and Atlantic waters of the Labrador Sea during the spring bloom (2013-2014). In this study, trait-based analysis using community-weighted means showed that low temperatures (< 0°C) in Arctic waters correlated positively with diatom species that have traits such as low temperature optimum growth and the ability to produced ice-binding proteins, highlighting their sea ice origin. High silicate concentrations in Arctic waters, as well as sea ice cover and shallow bathymetry, favoured diatom species that were heavily silicified, colonial and capable of producing resting spores, suggesting that these are important traits for this community. In Atlantic waters, diatom species with large surface area to volume ratios were dominant in deep mixed layers, whilst low silicate to nitrate ratios correlated positively with weakly silicified species. Sharp cell projections, such as processes or spines, were positively correlated with water-column stratification, indicating that these traits promote positive buoyancy for diatom cells. Our trait-based analysis directly links cell morphology and physiology with diatom species distribution, allowing new insights on how this method can potentially be applied to explain ecophysiology and shifting biogeographical distributions in a warming climate

Does α-Amino-β-methylaminopropionic Acid (BMAA) Play a Role in Neurodegeneration?

The association of α-amino-β-methylaminopropionic acid (BMAA) with elevated incidence of amyotrophic lateral sclerosis/Parkinson’s disease complex (ALS/PDC) was first identified on the island of Guam. BMAA has been shown to be produced across the cyanobacterial order and its detection has been reported in a variety of aquatic and terrestrial environments worldwide, suggesting that it is ubiquitous. Various in vivo studies on rats, mice, chicks and monkeys have shown that it can cause neurodegenerative symptoms such as ataxia and convulsions. Zebrafish research has also shown disruption to neural development after BMAA exposure. In vitro studies on mice, rats and leeches have shown that BMAA acts predominantly on motor neurons. Observed increases in the generation of reactive oxygen species (ROS) and Ca2+ influx, coupled with disruption to mitochondrial activity and general neuronal death, indicate that the main mode of activity is via excitotoxic mechanisms. The current review pertaining to the neurotoxicity of BMAA clearly demonstrates its ability to adversely affect neural tissues, and implicates it as a potentially significant compound in the aetiology of neurodegenerative disease. When considering the potential adverse health effects upon exposure to this compound, further research to better understand the modes of toxicity of BMAA and the environmental exposure limits is essential

Active Adenoviral Vascular Penetration by Targeted Formation of Heterocellular Endothelial–epithelial Syncytia

The endothelium imposes a structural barrier to the extravasation of systemically delivered oncolytic adenovirus (Ad). Here, we introduced a transendothelial route of delivery in order to increase tumor accumulation of virus particles (vp) beyond that resulting from convection-dependent extravasation alone. This was achieved by engineering an Ad encoding a syncytium-forming protein, gibbon ape leukemia virus (GALV) fusogenic membrane glycoprotein (FMG). The expression of GALV was regulated by a hybrid viral enhancer-human promoter construct comprising the human cytomegalovirus (CMV) immediate-early enhancer and the minimal human endothelial receptor tyrosine kinase promoter (“eTie1”). Endothelial cell-selectivity of the resulting Ad-eTie1-GALV vector was demonstrated by measuring GALV mRNA transcript levels. Furthermore, Ad-eTie1-GALV selectively induced fusion between infected endothelial cells and uninfected epithelial cells in vitro and in vivo, allowing transendothelial virus penetration. Heterofusion of infected endothelium to human embryonic kidney 293 (HEK 293) cells, in mixed in vitro cultures or in murine xenograft models, permitted fusion-dependent transactivation of the replication-deficient Ad-eTie1-GALV, due to enabled access to viral E1 proteins derived from the HEK 293 cytoplasm. These data provide evidence to support our proposed use of GALV to promote Ad penetration through tumor-associated vasculature, an approach that may substantially improve the efficiency of systemic delivery of oncolytic viruses to disseminated tumors

Deletion of the MAD2L1 spindle assembly checkpoint gene is tolerated in mouse models of acute T-cell lymphoma and hepatocellular carcinoma.

Chromosome instability (CIN) is deleterious to normal cells because of the burden of aneuploidy. However, most human solid tumors have an abnormal karyotype implying that gain and loss of chromosomes by cancer cells confers a selective advantage. CIN can be induced in the mouse by inactivating the spindle assembly checkpoint. This is lethal in the germline but we show here that adult T cells and hepatocytes can survive conditional inactivation of the Mad2l1 SAC gene and resulting CIN. This causes rapid onset of acute lymphoblastic leukemia (T-ALL) and progressive development of hepatocellular carcinoma (HCC), both lethal diseases. The resulting DNA copy number variation and patterns of chromosome loss and gain are tumor-type specific, suggesting differential selective pressures on the two tumor cell types