Search

Purpose: Fibrin sealant (FS) was approved as a hemostatic agent, sealant, and adhesive by the Food and Drug Administration in 1998. Our study sought to determine whether FS also reduced edema and pain in rhinoplasty without osteotomy.Materials and Methods: We conducted a prospective randomized trial involving patients who underwent open rhinoplasty without osteotomy. The patients were randomly assigned to 1 of 2 groups: those treated with aerosolized FS (FS group) and those not treated (control group). The effect of FS on edema of the eyelid, edema of the dorsum and tip of the nose, and periorbital ecchymosis was separately rated postoperatively using a scale of 0 to 4 or 0 to 3. Postoperative pain was evaluated using questionnaires quantified with a visual analog scale. The Mann-Whitney U and Wilcoxon tests were used to compare parameters between the groups.Results: A total of 41 patients were included in this study. The FS group (n = 20) consisted of 13 male and 7 female patients with a mean age of 34.8 ± 5.8 years. The control group (n = 21) consisted of 15 male and 6 female patients with a mean age of 32.4 ± 4.8 years. There were no statistically significant differences between the 2 groups with respect to age, gender, or combined surgical techniques (P > .05). Aerosolized FS significantly reduced not only ecchymosis and swelling in the periorbital area but also edema of the nasal dorsum (P < .05).Conclusions: Aerosolized FS can be effective for reducing eyelid edema, dorsal edema, and periorbital ecchymosis after open rhinoplasty. FS may serve as an adhesive for minimizing dead space by promoting adherence of the skin flap and as a hemostatic agent in reducing the amount of postoperative bleeding by sealing capillary vessels. [ABSTRACT FROM AUTHOR]

Perovskite solar cells (PSCs) have been significantly improved by utilizing an inorganic hole-transporting layer (HTL), such as nickel oxide. Despite the promising properties, there are still limitations due to defects. Recently, research on self-assembled monolayers (SAMs) is being actively conducted, which shows promise in reducing defects and enhancing device performance. In this study, we successfully engineered a p-i-n perovskite solar cell structure utilizing HC-A1 and HC-A4 molecules. These SAM molecules were found to enhance the grain morphology and uniformity of the perovskite film, which are critical factors in determining optical properties and device performance. Notably, HC-A4 demonstrated superior performance due to its distinct hydrophilic properties with a contact angle of 50.3°, attributable to its unique functional groups. Overall, the HC-A4-applied film exhibited efficient carrier extraction properties, attaining a carrier lifetime of 117.33 ns. Furthermore, HC-A4 contributed to superior device performance, achieving the highest device efficiency of 20% and demonstrating outstanding thermal stability over 300 h. [ABSTRACT FROM AUTHOR]

The Pacific Arctic Ocean has experienced a rapidly changing climate, sea-ice retreat, and enhanced primary production over the past few decades. The export production generated by photoautotrophs and heterotrophs has been characterized in the Arctic Ocean, but their seasonal variations in relative proportion are largely unknown due to the limited access in the ice-covered season. We measured the concentration and nitrogen isotope ratio of individual amino acids from sinking particles in the northern east Siberian Sea (KAMS1), northern Chukchi Sea (KAMS2), and Northwind Ridge (KAMS4) from August 2017 to July 2019. The average trophic position, based on differences in the nitrogen isotope ratios of glutamic acid and phenylalanine, can indicate the relative proportions of biogenic organic matters derived from photoautotrophs and heterotrophs in sinking particles. Decreasing values (close to 1.0) in summer at KAMS2 in 2018 suggest that primary producers are responsible for most of the downward flux of sinking particles. However, the average trophic position at KAMS1 in 2017 increased to >1.5 in autumn and was maintained at approximately 1.7 during ice-covered winter periods, likely due to greater contributions from heterotrophic organisms. Exceptionally high average trophic positions (close to 2.0) of sinking particles in summer at KAMS1 in 2017 and KAMS4 in 2018 were likely due to small export of photoautotrophs due to the surface seawater stratification and limited pelagic production. The average trophic position in sinking particles should reflect the spatiotemporal variation in export particle composition in the Pacific Arctic Ocean. • Biogenic sources of sinking particles in the Pacific Arctic Ocean were investigated using nitrogen isotopes of amino acids. • The trophic position of sinking particles reflected proportions of organic matter derived from autotroph and heterotroph. • The Arctic planktonic ecosystem showed dynamic spatiotemporal variability of the sources of sinking organic particles. [ABSTRACT FROM AUTHOR]

Low-concentration hypochlorous acid (HOCl) is an endogenous antibacterial and antiviral agent. The purpose of this study was to evaluate the effectiveness of HOCl irrigation in patients with chronic rhinosinusitis (CRS) refractory to medical therapy. Forty-three adult patients (mean age 45.5 years) were enrolled in this study. They were randomly chosen to receive nasal irrigation with either low-concentration HOCl generated by a Salicid device ( n = 21), or a placebo (saline; n = 22) for 8 weeks. The outcome measures were scores on the 20-Item SinoNasal Outcome Test (SNOT-20), rhinosinusitis disability index (RSDI), nasal endoscopic score, and bacterial cultures. The SNOT-20 scores were significantly lower in the HOCl group than in the placebo group after 2 weeks of treatment ( p < 0.05) and remained lower after 4 weeks of treatment. With respect to the RSDI scores, there was a significant improvement in the HOCl group at 1 week after treatment and in both groups at 2 weeks after treatment ( p < 0.05). There were no significant differences in the endoscopic scores between the two groups after the treatment. The bacterial culture rates were lower in the HOCl group than in the placebo group after 4 weeks of treatment, but this was not significant ( p > 0.05). Our results showed that low-concentration HOCl irrigation resulted in a greater improvement in CRS symptoms as compared to saline irrigation. [ABSTRACT FROM AUTHOR]

Hypertemporal image (HTI) is often used to exploit the seasonal characteristics of environmental phenomena such as sea ice concentration (SIC). However, it is difficult to analyse the long-term time series acquired at high temporal frequencies and over extensive areas. This study performed temporal mixture analysis (TMA), which is algebraically similar to spectral mixture analysis (SMA), but occurs in the time domain instead of the spectral domain. TMA was used to investigate the temporal characteristics of Antarctic sea ice. Because endmember (EM) selection is critical to the success of both SMA and TMA, it is important to select proper EMs from large quantities of HTI. In this study, a machine learning (ML) technique is incorporated in identifying EMs without prior information to address the limitations of previous research. A fully linear mixing model was then implemented in an attempt to produce more robust and physically meaningful abundance estimates. Experiments that quantitatively and qualitatively evaluated the proposed approaches were conducted. A TMA of high-temporal-dimensional data provides a unique summary of long-term Antarctic sea ice and noise-whitened reconstruction images via inverse processing. Furthermore, comparisons of regional sea ice fractions from experimental results enhance the understanding of the overall Antarctic sea ice changes. [ABSTRACT FROM PUBLISHER]

Photo-protective functions were investigated in phytoplankton assemblages at Kongsfjorden, Svalbard in spring, using their UV-absorbing compounds (mycosporine-like amino acids (MAAs)), xanthophyll pigments (diadinoxanthin (DD) and diatoxanthin (DT)) and < beta >- dimethylsulphoniopropionate (< beta >DMSP). The dominant phytoplankton species in the inner bay were dominated by Phaeocystis spp. and nanoflagellates, while the offshore waters were dominated by Thalassiosira spp. In the inner bay, UVabsorbing compounds and xanthophyll pigments exhibited higher ratios of MAA to chlorophyll a (MAA:chl a ratio), and both DD and DT to chlorophyll a (DD:chl a ratio and DT:chl a ratio), respectively. Thus, the photoprotective-pigments such as DD and DT appear to complement MAAs in the natural phytoplankton assemblage. However, the ratio of < beta >DMSP to chlorophyll a (< beta >DMSP:chl a ratio) did not show a distinct spatial distribution according to environmental factors or interspecies differences. In this study, we found that photoprotective compounds occurred in a manner dependent on the phytoplankton species composition in Kongsfjorden Bay, where Phaeocystis is the dominant species. [ABSTRACT FROM AUTHOR]

We investigated the microzooplankton community and its grazing impact on major phytoplankton groups in the Chukchi Sea and in the western Canada Basin during the period July–August 2010. The study area was divided into three regions based on topography, hydrographic properties and trophic conditions: (1) a productive region over the Chukchi Sea shelf (CSS) with high phytoplankton biomass dominated by diatoms, (2) an oligotrophic region over the Northwind Abyssal Plain (NwAP) with low phytoplankton biomass dominated by picophytoplankton, and (3) the Northwind Ridge (NwR), over which waters were dominated by picophytoplankton and diatoms. The spatial distribution of microzooplankton biomass and its composition were related to differences in phytoplankton biomass and assemblage composition in the three water masses. Heterotrophic dinoflagellates (HDF) and ciliates were significant components of microzooplankton populations. Athecate HDF was the most important component in the CSS, where diatoms were dominant. Naked ciliates were dominant microzooplankton in the NwR. Microzooplankton grazing rate varied by the assemblage composition of both phytoplankton and microzooplankton. Microzooplankton was capable of consuming an average of 71.7±17.2% of daily phytoplankton production. Growth rates of smaller phytoplankton (i.e., picophytoplankton and autotrophic nanoflagellates) and grazing rates on them were higher than rates for diatoms. Microzooplankton grazed more on picophytoplankton (PP grazed=89.3±20.5%) and autotrophic nanoflagellates (PP grazed=82.3±22.5%) than on diatoms (PP grazed=62.5±20.5%). The dynamics of predator and prey populations were almost balanced in waters in which smaller phytoplanktons were dominant. Picophytoplankton production was consumed by microzooplankton allowing transfer to larger consumers. On average, microzooplankton grazed 62.5% of the diatom production in the waters we studied, indicating that the classical food chain (with carbon flux from diatoms to copepods) is likely operational and of significance in this region. Overall, microzooplankton grazing was an important process controlling phytoplankton biomass and composition in the Chukchi Sea and the western Canada Basin during early summer. [ABSTRACT FROM AUTHOR]

Irradiance profiles were measured during the Korean 2012 summer Arctic Ocean cruise and optical properties were studied. The optical attenuation coefficient in all surface waters was low, as the nutrients in the surface layers became exhausted and phytoplankton growth was only possible at the subsurface where optimal conditions of nutrients and sufficient illumination existed. This high attenuation zone was at about 40–60 m. The attenuation properties were categorized to three types. Type-1 waters had weaker maximum attenuation coefficients and were located at the Chukchi Plateau and the north margin of the study region. Type-2 water had an intense maximum of attenuation coefficient up to 0.56/m located on west flank of Mendeleev Ridge and continental slope of East Siberian Sea. Two integral parameters, attenuation depth and optical thickness, were mapped by spatial distribution. The attenuation depth was basically shallower (40 m) to the west and deeper to the east (100 m). The averaged optical thickness at the level of 30–60 m was the main zone of high attenuation. Both the optical attenuation property and the physical features of the water indicated two subsurface water masses: one is the cold shelf water well mixed with river water and transported to the east by a subsurface current along the East Siberian Slope. The other is the warmer water from the Pacific with lower nutrients and transported to the northwest along the north margin of the observed region. A cyclonically re-circulated branch of shelf water passing over the Chukchi Abyssal Plain was described in this study. [ABSTRACT FROM AUTHOR]

Three new thieno[3,2- b][1]benzothiophene ( TBT)-based donor-π-acceptor (D-π-A) sensitizers, coded as SGT- 121, SGT- 129, and SGT- 130, have been designed and synthesized for dye-sensitized solar cells (DSSCs), for the first time. The TBT, prepared by fusing thiophene unit with the phenyl unit of triphenylamine donor, is utilized as the π-bridge for all sensitizers with good planarity. They have been molecularly engineered to regulate the highest occupied molecular orbital (HOMO)-lowest unoccupied molecular orbital (LUMO) energy levels and extend absorption range as well as to control the electron-transfer process that can ensure efficient dye regeneration and prevent undesired electron recombination. The photovoltaic performance of SGT-sensitizer-based DSSCs employing Co(bpy)32+/3+ (bpy = 2,2′-bipyridine) redox couple is systematically evaluated in a thorough comparison with Y123 as a reference sensitizer. Among them, SGT- 130 with benzothiadiazole-phenyl ( BTD- P) unit as an auxiliary acceptor exhibits the highest power-conversion efficiency (PCE) of 10.47% with Jsc = 16.77 mA cm−2, Voc = 851 mV, and FF = 73.34%, whose PCE is much higher than that of Y123 (9.5%). It is demonstrated that the molecular combination of each fragment in D-π-A organic sensitizers can be a pivotal factor for achieving the higher PCEs and an innovative strategy for strengthening the drawbacks of the π-bridge. [ABSTRACT FROM AUTHOR]

Viruses are important regulatory factors of the marine microbial community including microeukaryotes. However, little is known about their role in the northern Chukchi Sea in the Arctic basin, which has oligotrophic conditions in summer. To clarify the link between microbial eukaryotic communities and viruses as well as environmental conditions, we investigated the community structures of microeukaryotes (from 3 to144 μm and from 0.23 μm size bio‐particles collected from seawater) and Imitervirales (from 0.23 μm size bio‐particles collected from seawater), a dominant group of viruses infecting marine microeukaryotes. To the best of our knowledge, no study has investigated both Imitervirales and eukaryotic communities in the Arctic Ocean. Surface water samples were collected at 21 ocean stations located in the northeastern Chukchi Sea and an adjacent area outside the Beaufort Gyre (Adjacent Sea), and at two melt ponds on sea ice in the summer of 2018. At the ocean stations, nutrient concentrations were low in most of the locations, except the shelf in the adjacent sea. The community variations were significantly correlated between eukaryotes and Imitervirales, even within the northeastern Chukchi Sea characterized by relatively homogeneous environmental conditions. The association of the eukaryotic community with the viral community was stronger than that with geographical and physicochemical environmental factors. These results suggest that Imitervirales actively infect their hosts even in the cold and oligotrophic seawater in the Arctic Ocean. [ABSTRACT FROM AUTHOR]

Abstract: The primary production of bottom ice algae is an important food source for sympagic, pelagic and benthic organisms in the Arctic Ocean as well as Antarctic Ocean. Using 13C-15N isotope tracers, the recent ice algal production at Barrow during the spring season was lower in 2003 than three decades ago, although the maximum chlorophyll-a concentration for the bottom ice algae was similar to the values from previous studies. Estimated recent new and total production rates of the ice algae were 0.8 g C m-2 yr-1 and 2.0 g C m-2 yr-1 respectively, while the rates of water column phytoplankton were 0.2 g C m-2 yr-1 and 0.7 g C m-2 yr-1 for the spring sampling period in 2003. The ice algae contributed 74% of the pelagic primary production under the landfast sea ice at Barrow before the phytoplankton spring bloom. At the end of the season in 2003, a high carbon allocation of lipids in the ice algae was found. Three possible explanations- nutrient depletion, increasing light, and/or changes in species composition- were suggested for the high carbon incorporation into lipids. This high lipid synthesis of the bottom ice algae might be significant to zooplankton and benthic fauna grazers because lipids are the most energy dense biomolecules. [Copyright &y& Elsevier]

Abstract: Cruises to Bering Strait and the Chukchi Sea in US waters from late June in 2002 to early September in 2004 and the Russian–American Long-term Census of the Arctic (RUSALCA) research cruise in 2004 covered all major water masses and contributed to a better understanding of the regional physics, nutrient dynamics, and biological systems. The integrated concentration of the high nitrate pool in the central Chukchi Sea was greater in this study than in previous studies, although the highest nitrate concentration (∼22μM) in the Anadyr Water mass passing through the western side of Bering Strait was consistent with prior observations. The chlorophyll-a concentrations near the western side of the Diomede Islands ranged from 200 to 400mgchl-a m−2 and the range in the central Chukchi Sea was 200–500mgchl-a m−2 for the 2002–2004 Alpha Helix (HX) cruises. Chlorophyll-a concentrations for the 2004 RUSALCA cruise were lower than those from previous studies. The mean annual primary production of phytoplankton from this study, using a 13C–15N dual-isotope technique, was 55gCm−2 for the whole Chukchi Sea and 145gCm−2 for the plume of Anadyr–Bering Shelf Water in the central Chukchi Sea. In contrast, the averages of annual total nitrogen production were 13.9gNm−2 (S.D.=±16.2gNm−2) and 33.8gNm−2 (S.D.=±14.1gNm−2) for the Chukchi Sea and the plume, respectively. These carbon and nitrogen production rates of phytoplankton were consistently two-or three-fold lower than those from previous studies. We suggest that the lower rates in this study, and consequently more unused nitrate in the water column, were caused by lower phytoplankton biomass in the Bering Strait and the Chukchi Sea. However, we do not know if the lower rate of production from this study is a general decreasing trend or simply temporal variations in the Chukchi Sea, since temporal and geographical variations are substantially large and presently unpredictable. [Copyright &y& Elsevier]

Human activities such as fossil fuel combustion, land-use change, nitrogen (N) fertilizer use, emission of livestock, and waste excretion accelerate the transformation of reactive N and its impact on the marine environment. This study elucidates that anthropogenic N fluxes (ANFs) from atmospheric and river deposition exacerbate Arctic warming and sea ice loss via physical–biological feedback. The impact of physical–biological feedback is quantified through a suite of experiments using a coupled climate–ocean–biogeochemical model (GFDL-CM2.1-TOPAZ) by prescribing the preindustrial and contemporary amounts of riverine and atmospheric N fluxes into the Arctic Ocean. The experiment forced by ANFs represents the increase in ocean N inventory and chlorophyll concentrations in present and projected future Arctic Ocean relative to the experiment forced by preindustrial N flux inputs. The enhanced chlorophyll concentrations by ANFs reinforce shortwave attenuation in the upper ocean, generating additional warming in the Arctic Ocean. The strongest responses are simulated in the Eurasian shelf seas (Kara, Barents, and Laptev Seas; 65°–90°N, 20°–160°E) due to increased N fluxes, where the annual mean surface temperature increase by 12% and the annual mean sea ice concentration decrease by 17% relative to the future projection, forced by preindustrial N inputs. [ABSTRACT FROM AUTHOR]

Consecutive intramolecular desymmetrization and kinetic resolution of 2-substituted N-phenoxycarbonylserinols have been achieved in one-pot by a single chiral catalyst, bisox(7)–CuCl2, to form oxazolidinones with remarkable enantioselectivities (94–99% ee) as tert-alkylamine building blocks. The process culminates in a dual-function of the chiral catalyst. [ABSTRACT FROM AUTHOR]

(−)-Kaitocephalin has been synthesized. With the C9 stereocenter from Garner's aldehyde, the C4 quaternary carbon was installed by the desymmetrization of the Cbz-protected serinol. The remaining stereogenic centers were generated through mercuriocyclization, epoxidation and regioselective epoxide opening, in which the quaternary carbon most likely played crucial roles in the stereoinduction. [ABSTRACT FROM AUTHOR]

Retinal swelling due to the accumulation of fluid is associated with the most vision-threatening retinal diseases. Optical coherence tomography (OCT) is the current standard of care in assessing the presence and quantity of retinal fluid and image-guided treatment management. Deep learning methods have made their impact across medical imaging, and many retinal OCT analysis methods have been proposed. However, it is currently not clear how successful they are in interpreting the retinal fluid on OCT, which is due to the lack of standardized benchmarks. To address this, we organized a challenge RETOUCH in conjunction with MICCAI 2017, with eight teams participating. The challenge consisted of two tasks: fluid detection and fluid segmentation. It featured for the first time: all three retinal fluid types, with annotated images provided by two clinical centers, which were acquired with the three most common OCT device vendors from patients with two different retinal diseases. The analysis revealed that in the detection task, the performance on the automated fluid detection was within the inter-grader variability. However, in the segmentation task, fusing the automated methods produced segmentations that were superior to all individual methods, indicating the need for further improvements in the segmentation performance. [ABSTRACT FROM AUTHOR]

To clarify the influence of sea ice concentration on phytoplankton community distribution in the rapidly warming Arctic Ocean, we conducted field surveys in August 2012 and August 2015 in the Chukchi and East Siberian Seas. The phytoplankton community structures (derived from pigment analysis) were compared according to environmental variables between the two periods. August 2012 had the lowest average sea ice concentration since sea ice observations began in 1979, along with higher sea surface temperatures. A deeper mixed layer depth and higher surface nitrate concentrations were observed in 2012, caused by exposure of the sea surface to wind. The euphotic depth and subsurface chlorophyll maximum layer were deeper in 2015 than in 2012, and whereas the low surface phytoplankton biomass in both years indicated post-bloom periods. Similar phytoplankton biomass and different phytoplankton community structure were found between ice and melt years. Small phytoflagellates (e.g., prymnesiophytes, prasinophytes, dinoflagellates, and cryptophytes) dominated the phytoplankton biomass with different community structures in the eastern and western areas in 2012, while diatoms dominated over the whole study area in 2015. Several environmental factors affect the variation in phytoplankton community structure in the Chukchi and East Siberian Seas; however, the phytoplankton, especially diatoms, appeared to be controlled mainly by seeding from sea ice in the surface layer. Furthermore, euphotic depth and water mass structure are likely the main factors influencing the spatial distribution of phytoplankton in the subsurface layer of this area, indicating that the phytoplankton community structure might be influenced by the water mass distribution under future ice-free conditions. • Similar phytoplankton biomass and different phytoplankton community structures between ice and melt years. • The distribution of phytoplankton, especially diatoms might be influenced by the sea ice concentration in the study area. • Phytoplankton community structure is likely to be more water-mass-specific in the ice-free period. [ABSTRACT FROM AUTHOR]

Abstract During the RV-ARAON cruise, a comparative study on the biosynthesis of mycosporine-like amino acids (MAAs) was conducted for the size-fractionated phytoplankton of the Beaufort Sea (Arctic). The MAAs contents in the micro-phytoplankton community (>20 μm size) is considerably higher than that observed in the nano- (20–2 μm size) and pico-phytoplankton (<2 μm size) communities. The micro-phytoplankton of the Mackenzie Shelf had a relatively higher Chlorophyll a (Chl a) concentration. Considering the total phytoplankton community, the MAAs concentration as well as net production of individual MAAs (such as shinorine and palythine) were higher at the Mackenzie Shelf rather than at the sites located beyond the Beaufort Sea; precisely, the highest net production rates of shinorine and palythine were 0.211 (±0.02) ng C L−1 d−1 and 0.136 (±0.001) ng C L−1 d−1 respectively (No other MAAs were detected). The micro-phytoplankton used around 0.5% of the total carbon uptake for the synthesis of MAAs. Compared to the smaller phytoplankton community, the micro-phytoplankton utilized more of their energy for the biosynthesis of MAAs; on the other hand, nano- and pico-phytoplankton focused on cellular activity and had poor biosynthesis of MAAs. This clearly indicates the phytoplankton size-dependent variation in the biosynthesis of MAA in the natural phytoplankton community. This study revealed the environmental adaptation of the various sizes of phytoplankton community as well as their physiological response in the Arctic Beaufort Sea. Highlights • MAAs contents in the micro-phytoplankton are considerably higher than other smaller phytoplankton • MAAs concentration and net production were higher at the Mackenzie Shelf than other sites • Phytoplankton size-dependent variation was found in the MAAs biosynthesis in the Arctic Beaufort Sea [ABSTRACT FROM AUTHOR]

The carbon allocations of phytoplankton into different photosynthetic end products (lipids, LMWM, polysaccharides, and proteins) were determined to understand physiological conditions of phytoplankton in the northern Chukchi Sea during the Korean Arctic expedition, 2011, using the 13 C isotope tracer technique. The carbon allocation rates of lipids, LMWM, polysaccharides, and proteins were 0.00009–0.00062 h −1 , 0.00001–0.00049 h −1 , 0.00001–0.00025 h −1 , and 0.00001–0.00062 h −1 within the euphotic depths from surface to 1% light depths during our cruise period, respectively. Significant relationships between protein production rates and chlorophyll a concentrations (large and total) were found in this study. Moreover, we found a significant negative relationship between lipid production rates and ammonium concentrations. These relationships match well with the previous results for environmental/physiological conditions for phytoplankton growth. Overall, phytoplankton allocated more photosynthetic carbon into lipids (42.5 ± 17.7%) whereas relatively lower to proteins (20.4 ± 15.5%) in this study. The lipid-rich and protein-poor allocation patterns in this study suggest that phytoplankton in the northern Chukchi Sea were in a stationary growth phase under nutrient deficient condition based on biological and environmental conditions observed during our study period. Based on comparison with the previous studies in the northern Bering Sea and southern Chukchi Sea, we found that the photosynthetic carbon allocation patterns depending on physiological status of phytoplankton under the different growth and/or nutrient conditions could be largely vary at different regions in the Arctic Ocean. More intensive research on the physiological status of phytoplankton is further required to determine how phytoplankton response to the changing environmental conditions and consequently how they impact on higher trophic levels in marine ecosystems in the Arctic Ocean. [ABSTRACT FROM AUTHOR]

In recent decades, the Yellow Sea has experienced severe environmental deterioration due to increasing input of anthropogenic pollutants and consequently accelerated eutrophication. Whilst there have been significant advances in documenting historical records of metal pollution in the Yellow Sea region, changes in phytoplankton community structures affected by eutrophication remain understudied. Here, we present a new record of dinoflagellate cyst-based signals in age-dated sediment cores from the Yellow Sea mud deposits to provide better insight into eutrophication history and identification of associated responses of the regional phytoplankton community. It is worthy of note that there were significant variations in abundances and community structures of dinoflagellate cysts in three historical stages in association with increasing anthropogenic activity over the last 400 years. Pervasive effects of human interference altering the Yellow Sea environments are recognized by: 1) an abrupt increase of organic matter, including the diatom-produced biogenic opal concentrations (∼1850); 2) a distinct shift in phytoplankton composition towards dinoflagellate dominance (∼1940), and 3) recent acceleration of dinoflagellate cyst accumulation (∼1990). Particularly in the central Yellow Sea shelf, the anomalously high deposition of dinoflagellate cysts (especially Alexandrium species) is suggested to be a potentially important source of inoculum cells serving as a seed population for localized and recurrent blooms in coastal areas around the Yellow Sea. [ABSTRACT FROM AUTHOR]

Sedimentation processes influenced by late Cenozoic ice-sheet dynamics and bottom-current activity can be extracted from the seismic stratigraphic record of the Ross Sea continental slope and rise, where more continuous sedimentary successions are preserved compared to the continental shelf. In this study, we present a seismic stratigraphic analysis of the Central Basin that lies in the northwestern Ross Sea, using newly acquired and existing legacy seismic reflection data that are correlated to adjacent scientific drill sites. The chronostratigraphy of Ross Sea seismic sequences lying above the mid-Miocene sequence boundary (RSU4, ca. 16.5–15.5 Ma) is based on the former Antarctic Offshore Stratigraphy (ANTOSTRAT) project. Depth-contour and isopach maps of sedimentary sequences bounded by two major unconformities of RSU4 and RSU2 (the late Pliocene boundary, ca. 4.0–2.8 Ma) and the present-day seafloor were produced to illustrate the evolution of paleo-seafloor morphology, distribution of sediments and depocenter migration in the western Ross Sea outer margin. The results of seismic stratigraphic analysis indicate that gravity sedimentation processes dominated the Central Basin infill up to the mid-Miocene, and then downslope sediment supply gradually diminished through the late Miocene and Quaternary, likely reflecting a shift toward a cooler, less erosive glacial regime change. Since the late Pliocene, a topset-truncated glacial prograding wedge developed in the upper continental slope at the mouth of the Joides Basin and the sediment depocenter was shifted from the basin floor to the upper slope, suggesting the more persistent occurrence of grounded ice sheets on the outer continental shelf. Meanwhile, persistent along-slope bottom-current processes formed contourites on the slope and over the crests of banks surrounding the Central Basin since the mid-Miocene. In the late Pliocene, the contourites that formed off the Joides Basin mouth were overlain by glaciogenic debris flows, while the growth of contourites continued over and along the flanks of banks, farther to the north. This suggests that along-slope bottom-current processes near the Joides Basin mouth were diminished or dominated by the glacial discharge to the continental shelf edge. The sediment stacking patterns differ between the Joides/Central Basins and the Drygalski/Adare Basins located on the westernmost Ross Sea margin, suggesting that distinctive glacial/interglacial behavior of the former grounded ice streams and sediment supplies in the troughs feeding these basins were largely controlled by the paleo-seafloor morphology of the western Ross Sea continental shelf. [ABSTRACT FROM AUTHOR]

ArcticChlamydomonassp. is a dominant microalgal strain in cold or frozen freshwater in the Arctic region. The full-length open reading frame of the omega-6 fatty acid desaturase gene (AChFAD6) was obtained from the transcriptomic database of ArcticChlamydomonassp. from the KOPRI culture collection of polar micro-organisms. Amino acid sequence analysis indicated the presence of three conserved histidine-rich segments as unique characteristics of omega-6 fatty acid desaturases, and three transmembrane regions transported to plastidic membranes by chloroplast transit peptides in the N-terminal region. The AChFAD6 desaturase activity was examined by expressing wild-type and V254A mutant (Mut-AChFAD6) heterologous recombinant proteins. Quantitative gas chromatography indicated that the concentration of linoleic acids inAChFAD6-transformed cells increased more than 3-fold [6.73 ± 0.13 mg g−1dry cell weight (DCW)] compared with cells transformed with vector alone. In contrast, transformation with Mut-AChFAD6increased the concentration of oleic acid to 9.23 ± 0.18 mg g−1DCW, indicating a change in enzymatic activity to mimic that of stearoyl-CoA desaturase. These results demonstrate that AChFAD6 of ArcticChlamydomonassp. increases membrane fluidity by enhancing denaturation of C18 fatty acids and facilitates production of large quantities of linoleic fatty acids in prokaryotic expression systems. [ABSTRACT FROM PUBLISHER]

• Biogeography of dinoflagellate cysts in the Pacific Arctic Ocean were investigated. • Strong regionality infers a growing impact of southern waters on warming Arctic Ocean. • Toxic- Alexandrium cyst accumulations point to potential bloom initiation in Arctic Ocean. • Dinoflagellate cysts are useful indicators of Arctic marine conditions under global warming. The Pacific sector of the Arctic Ocean, a region with the fastest sea-ice loss in recent decades, is experiencing unprecedented biological regime shifts in its marine ecosystems today. However, a shelf-wide characterization of marine plankton communities over this region and environmental processes behind it remain largely unresolved, despite phytoplankton phenology is now considered to be an important factor for assessing how Arctic Ocean interacts with global climate change. Here, we present the first detailed description of recent dinoflagellate cyst assemblages in 32 surface sediment samples from the Chukchi–East Siberian Sea shelves, the Pacific Arctic Ocean, to examine their biogeographic patterns and associated environmental forcing factors. We find a strong regionalization in the species composition and distribution along the shallow-shelf cyst accumulation zone; in the Chukchi Sea sector, northward flow of warm-Pacific water along with extreme seasonality, sufficient nutrient supplies and higher light availability leads to a large occupation of cosmopolitan, opportunistic-nature taxa, whilst the East Siberian Sea sector with more extensive sea-ice cover and lower temperatures is primarily dominated by "round brown spiny cyst" taxa that have a strong affinity for cold, polar conditions. Specifically, an exclusive dominance of heterotrophic taxa at the East Siberian Sea region is inferred to be closely tied to Atlantic-origin water intrusions that lift nutrient-rich, cold bottom water up to oligotrophic surface layer to grow diatoms and other prey organisms. The observed contrast in this geographical "hot spot", where the Pacific- and Atlantic-origin waters face each other, clearly manifests a growing expansion of southern waters into an increasingly ice-free Arctic Ocean that reshapes Arctic Ocean biogeography from the base of marine food chains. Our study highlights considerable potential of dinoflagellate cysts as a valuable environmental proxy to indicate complex interactions between ocean physics and marine biology under the rapidly changing Arctic climate system. [ABSTRACT FROM AUTHOR]

The venerid clam ( Mactra veneriformis Reeve 1854) is one of the main cultured bivalve species in intertidal and shallow subtidal ecosystems along the west coast of Korea. To understand the effects of ocean acidification on the early life stages of Korean clams, we investigated shell growth and abnormality rates and types in the D-shaped, umbonate veliger, and pediveliger stages of the venerid clam M. veneriformis during exposure to elevated seawater pCO. In particular, we examined abnormal types of larval shell morphology categorized as shell deformations, shell distortions, and shell fissures. Specimens were incubated in seawater equilibrated with bubbled CO-enriched air at (400±25)×10 (ambient control), (800±25)×10 (high pCO), or (1 200±28)×10 (extremely high pCO), the atmospheric CO concentrations predicted for the years 2014, 2084, and 2154 (70-year intervals; two human generations), respectively, in the Representative Concentration Pathway (RCP) 8.5 scenario. The mean shell lengths of larvae were significantly decreased in the high and extremely high pCO groups compared with the ambient control groups. Furthermore, under high and extremely high pCO conditions, the cultures exhibited significantly increased abundances of abnormal larvae and increased severity of abnormalities compared with the ambient control. In the umbonate veliger stage of the experimental larvae, the most common abnormalities were shell deformations, distortions, and fissures; on the other hand, convex hinges and mantle protuberances were absent. These results suggest that elevated CO exerts an additional burden on the health of M. veneriformis larvae by impairing early development. [ABSTRACT FROM AUTHOR]

Antarctica is considered a relatively uncontaminated region with regard to the infectious diseases because of its extreme environment, and isolated geography. For the genetic characterization and molecular epidemiology of the newly found penguin adenovirus in Antarctica, entire genome sequencing and annual survey of penguin adenovirus were conducted. The entire genome sequences of penguin adenoviruses were completed for two Chinstrap penguins (Pygoscelis antarctica) and two Gentoo penguins (Pygoscelis papua). The whole genome lengths and G+C content of penguin adenoviruses were found to be 24,630–24,662 bp and 35.5–35.6%, respectively. Notably, the presence of putative sialidase gene was not identified in penguin adenoviruses by Rapid Amplification of cDNA Ends (RACE-PCR) as well as consensus specific PCR. The penguin adenoviruses were demonstrated to be a new species within the genus Siadenovirus, with a distance of 29.9–39.3% (amino acid, 32.1–47.9%) in DNA polymerase gene, and showed the closest relationship with turkey adenovirus 3 (TAdV-3) in phylogenetic analysis. During the 2008–2013 study period, the penguin adenoviruses were annually detected in 22 of 78 penguins (28.2%), and the molecular epidemiological study of the penguin adenovirus indicates a predominant infection in Chinstrap penguin population (12/30, 40%). Interestingly, the genome of penguin adenovirus could be detected in several internal samples, except the lymph node and brain. In conclusion, an analysis of the entire adenoviral genomes from Antarctic penguins was conducted, and the penguin adenoviruses, containing unique genetic character, were identified as a new species within the genus Siadenovirus. Moreover, it was annually detected in Antarctic penguins, suggesting its circulation within the penguin population. [ABSTRACT FROM AUTHOR]