Sources and spatial variations of heavy metals in offshore sediments of the western Pearl River Estuary.

The concentrations of six heavy metals (Cd, Cr, Cu, Pb, Zn, and As) in offshore surface sediments of western Pearl River Estuary were analyzed to investigate their sources and spatial variations using factorial kriging analysis. Three-scale spatial variations in heavy metal concentrations were identified and separated: nugget, local, and regional scale, which indicated sample errors, anthropogenic pollution and natural variation, respectively. Anthropogenic heavy metals varied sharply and heterogeneous at range of 60 km. Maoming Port, Hailing Bay and coastal area northeastern Hainan Island were potential polluted areas of Cd, Cr, Cu, Pb, Zn and As, also the Nandu River, Baoling River and Wanquan River estuaries were potential polluted areas of As. These polluted areas ranged up to 60 km in size and tended to extend with currents. The natural heavy metals varied continuously and relatively homogeneous at range of 180 km, which was dominated by riverine input and paleo-sea-level changes.

Enhancing Natural Killer Cell-Mediated Cancer Immunotherapy by the Biological Macromolecule Nocardia rubra Cell-Wall Skeleton.

The biological macromolecule Nocardia rubra cell-wall skeleton (Nr-CWS) has well-established immune-stimulating and anti-tumor activities. However, the role of Nr-CWS on natural killer (NK) cells remains unclear. Here, we explore the function and related mechanisms of Nr-CWS on NK cells. Using a tumor-bearing model, we show that Nr-CWS has slightly effect on solid tumor. In addition, using a tumor metastasis model, we show that Nr-CWS suppresses the lung metastasis induced by B16F10 melanoma cells in mice, which indicates that Nr-CWS may up-regulate the function of NK cells. Further investigation demonstrated that Nr-CWS can increase the expression of TRAIL and FasL on spleen NK cells from Nr-CWS treated B16F10 tumor metastasis mice. The spleen index and serum levels of TNF-α, IFN-γ, and IL-2 in B16F10 tumor metastasis mice treated with Nr-CWS were significantly increased. In vitro, the studies using purified or sorted NK cells revealed that Nr-CWS increases the expression of CD69, TRAIL, and FasL, decreases the expression of CD27, and enhances NK cell cytotoxicity. The intracellular expression of IFN-γ, TNF-α, perforin (prf), granzyme-B (GrzB), and secreted TNF-α, IFN-γ, IL-6 of the cultured NK cells were significantly increased after treatment with Nr-CWS. Overall, the findings indicate that Nr-CWS could suppress the lung metastasis induced by B16F10 melanoma cells, which may be exerted through its effect on NK cells by promoting NK cell terminal differentiation (CD27lowCD11bhigh), and up-regulating the production of cytokines and cytotoxic molecules.

Hyaluronic acid functionalized ZnO nanoparticles co-deliver AS and GOD for synergistic cancer starvation and oxidative damage.

Artesunate was reported to have inhibition effect on tumors via amplified oxidative stress while the lack of intratumoral ferrous ions supply greatly hinders its efficacy. Herein, the AS/GOD@HAZnO NPs we proposed could be efficiently taken in by the affinity between hyaluronic acid and the CD44 receptors. DLS and TEM results manifested the nano-size (~ 160 nm) and circular shape of AS/GOD@HAZnO NPs. Due to the acid-responsive degradation, AS/GOD@HAZnO NPs realized responsive release (up to 80%) in acid environment while only 20% was released in neutral medium. The cellular and in vivo experiment showed that co-delivery of AS and GOD via HAZnO NPs could effectively induce the overproduction of ROS and cut the glucose supply of tumor cells, and thus result in efficient cell apoptosis and tumor inhibition.

Highly Biocompatible Apigenin-Loaded Silk Fibroin Nanospheres: Preparation, Characterization, and Anti-Breast-Cancer Activity.

Breast cancer is among the most common fatal diseases among women. Low-toxicity apigenin (AGN) is of interest due to its good antitumor activity, but its clinical application is severely limited due to its poor water solubility and low bioavailability. An effective strategy to enhance the anti-breast-cancer activity of AGN is to develop it as a nanodelivery system. Silk fibroin (SF) is an ideal drug carrier with good biocompatibility, biodegradability, and a simple extraction process. This paper develops a novel and efficient apigenin-loaded silk fibroin nanodelivery system (SF-AGN) by nanoprecipitation with SF as a carrier. The system was characterized in terms of morphology, zeta potential, particle size, ultraviolet (UV), infrared (IR), and synchronous thermal analyses (TG-DSC), and the in vitro cytotoxicity and in vivo pharmacokinetics were examined. Finally, the chronic toxicity of SF-AGN in mice was studied. The SF-AGN nanodelivery system has good dispersibility, a hydrated particle size of 163.35 nm, a zeta potential of -18.5 mV, an average drug loading of 6.20%, and good thermal stability. MTT studies showed that SF-AGN significantly enhanced the inhibitory effect of AGN on 4T1 and MDA-MB-231 cells. Pharmacokinetic studies have demonstrated that SF-AGN can dramatically improve the bioavailability of AGN. The results of toxicity experiments showed that SF-AGN is biocompatible and does not alter normal tissues or organs. In sum, the SF-AGN nanodelivery system is a promising drug-delivery system for the clinical treatment of breast cancer.

Distribution characteristics and environmental fate of PCBs in marine sediments at different latitudinal regions: Insights from congener profiles.

Sediments were sampled from Hangzhou Bay (HB), the South China Sea (SCS), and Antarctica (AZ) to better understand the distribution characteristics and environmental fate of polychlorinated biphenyls (PCBs) at different latitudes. Numerous PCB congeners (68) were detected among the sampling sites, supporting the ubiquity of PCB congeners. High and low chlorinated congeners dominated the PCB profiles of AZ and SCS, respectively, whereas the PCB homologues were evenly distributed in the HB. As a fraction of low chlorinated PCBs originates from an exogenous input, the low mean ratios of ∑Tetra-CBs to ∑PCBs and ∑Tetra-CBs to the sum of ∑Tri- and ∑Di-CBs suggest that microbial transformation of PCBs is weak in marine surface sediments, if any occurs at all. Furthermore, PCB contamination levels in marine sediments may be primarily influenced by latitude rather than pollution sources. Thus, the findings of this study suggest that Antarctica is becoming a prospective hotspot for PCBs.

Sequential extraction procedure to obtain the composition of terrigenous detritus in marine sediments.

The geochemical and isotopic composition of terrigenous clays from marine sediments can provide important information on the sources and pathways of sediments. In order to extract the detrital signal from bulk marine sediments, standard sediment leaching methods are commonly applied to remove carbonate and ferromanganese oxides. In comparison to most previous studies that aimed to extract the terrestrial signal from marine sediments we additionally applied a CsCl wash throughout the sample preparation Simon et al. [1]. The motivation behind that extra step, not frequently applied, is to remove ions that are gained on the clay surface due to re-adsorption of authigenic trace metals in the ocean or during the leaching procedure and thus could alter the original composition of the detrital fraction if no cation exchange was applied. Here we present an improved and detailed step-by-step leaching protocol for the extraction of the detrital fraction of bulk deep-sea sediments including commonly used buffered acetic acid and acid-reductive mix solutions including a final cation exchange wash.•standard method to remove carbonate and ferromanganese oxides and Stokes settling to isolate the clay fractions•additional application of cation cation exchange wash (CsCl)•removal of ions that are gained on the clay surface due to adsorption of authigenic trace metals in the ocean or during the leaching procedure.

Are bacterial communities associated with microplastics influenced by marine habitats?

This study investigates the influence of marine habitats (i.e., the intertidal zone, supralittoral zone, and seawater), and polymer types (i.e., polyethylene, PE; polyethylene terephthalate, PET) on the diversity and structure of bacterial communities in marine microplastics. A three-month exposure experiment was conducted in Zhairuoshan Island, Zhoushan, China, a typical caldera volcanic island with minor anthropogenic disturbances. At the end of the exposure period, the transition for peaks corresponding to oxidized groups was observed using micro-Fourier transform infrared spectroscopy. Damages, including pits and cracks, and microorganisms were observed on the surfaces of the PE and PET pellets using scanning electron microscopy. Next-generation amplicon sequencing of the bacterial communities that had colonized the microplastics revealed that bacterial composition significantly varied depending on marine habitats and exposure times, rather than polymer type. Plastic debris in the intertidal zone exhibited the highest bacterial richness and diversity, and Bacillus was considered a potential degrader of plastic debris. The findings demonstrate that bacterial communities that colonize on microplastics are more potentially shaped by marine habitat and exposure time, and this would deepen our understanding of the ecological niche of microplastics surface.

The distribution characteristics of polychlorinated biphenyls (PCBs) in the surface sediments of Ross Sea and Drake Passage, Antarctica: A 192 congeners analysis.

A total of 23 sediment samples are collected from Ross Sea and Drake Passage to investigate the distribution characteristics of polychlorinated biphenyls (PCBs) in the Antarctic marine sediments. Over 51 kinds of PCBs are detected through exhaustive searches using multiple reaction monitoring system. The results show that the concentration of individual PCB congener and total PCBs vary greatly among sampling sites, ranging from not detected to 49.75 ng g-1 and 3.77 to 246.86 ng g-1, respectively. The average PCBs level in Ross Sea is ten times higher than that in Drake Passage. Two different homologues, hexa- and tetra-CBs, give high contributions to ∑PCBs level in most samples from Ross Sea and Drake Passage, respectively. Our results support that the marine sediments might be an important sink for PCBs. Besides, the biological pump and the primary productivity might be responsible for the distribution differences of PCBs between Ross Sea and Drake Passage.

Culture-Dependent and -Independent Analyses Reveal the Diversity, Structure, and Assembly Mechanism of Benthic Bacterial Community in the Ross Sea, Antarctica.

The benthic bacterial community in Antarctic continental shelf ecosystems are not well-documented. We collected 13 surface sediments from the Ross Sea, a biological hotspot in high-latitude maritime Antarctica undergoing rapid climate change and possible microflora shift, and aimed to study the diversity, structure and assembly mechanism of benthic bacterial community using both culture-dependent and -independent approaches. High-throughput sequencing of 16S rRNA gene amplicons revealed 370 OTUs distributed in 21 phyla and 284 genera. The bacterial community was dominated by Bacteroidetes, Gamma- and Alphaproteobacteria, and constituted by a compact, conserved and positively-correlated group of anaerobes and other competitive aerobic chemoheterotrophs. Null-model test based on ßNTI and RCBray indicated that stochastic processes, including dispersal limitation and undominated fractions, were the main forces driving community assembly. On the other hand, environmental factors, mainly temperature, organic matter and chlorophyll, were significantly correlated with bacterial richness, diversity and community structure. Moreover, metabolic and physiological features of the prokaryotic taxa were mapped to evaluate the adaptive mechanisms and functional composition of the benthic bacterial community. Our study is helpful to understand the structural and functional aspects, as well as the ecological and biogeochemical role of the benthic bacterial community in the Ross Sea.

Sources and burial fluxes of sedimentary organic carbon in the northern Bering Sea and the northern Chukchi Sea in response to global warming.

The Arctic and subarctic seas are the major CO2 sink areas on earth. In this study, the vertical variation characteristics of organic carbon, total nitrogen and their ratio (Corg/Nt), stable isotopes δ13C and δ15N, and BIT (branched and isoprenoid tetraether) index of GDGTs (glycerol dialkyl glycerol tetraethers) in combination with 210Pb-dating were used to analyze the changes in the marine and terrestrial sources of organic carbon in the northern Bering Sea (site 1), western Beaufort Sea slope (site 2) and northern Chukchi Sea (site 3). Organic carbon burial fluxes (OCBF) in the context of global warming were also explored at sites 1 and 3. The results showed that organic matter in these sediments were a mixed input of marine and terrestrial sources, and the BIT index and δ13C of site 2 suggested that the terrestrial soil organic matter was dominant. Based on a combination of 210Pb dating and Corg, the sedimentary OCBF at site 1 was 2.29-3.65 mg cm-2 y-1, and at site 3 was 0.00-0.41 mg cm-2 y-1. The temperature anomalies and sea ice changes in the Arctic in the past 100 years were compared with the burial fluxes of the terrestrial organic carbon. At site 1, the results indicated that fast melting of seasonal sea ice led to earlier arrival of ice algae bloom, enhanced zooplankton feeding and reduced carbon burial from 1947 to 2010, and the sudden increase in carbon burial after 2010 was attributed to an increase in primary productivity and terrestrial organic matter input due to an accelerated melting of sea ice. There was a smaller change in marine organic carbon content in site 3, but OCBF increased after a pre-1965 decrease, mainly controlled by terrestrial organic matter input associated with temperature rising and sea ice melting during recent decades.

Gramella antarctica sp. nov., isolated from marine surface sediment.

A Gram-stain-negative, aerobic, yellow-coloured, motile by gliding, rod-shaped bacterial strain, designated R17H11T, was isolated from surface sediment collected from the Ross Sea, Antarctica. Growth optimally occurred at 25-30 °C, at pH 7.0-7.5 and in the presence of 3 % NaCl (w/v). Phylogenetic trees based on 16S rRNA gene sequences indicated that strain R17H11T clustered together with Gramella flava JLT2011T and fell within the genus Gramella. Strain R17H11T shared the highest 16S rRNA gene similarities (96.1 and 96.0 %) with the type strains of Gramella forsetii and G. flava, and 92.6-95.5 % similarities with those of other known Gramella species. Strain R17H11T contained menaquinone-6 as the only isoprenoid quinone. The major fatty acids (>5 %) were summed feature 3 (17.5 %, comprising C16 : 1ω7c and/or C16 : 1ω6c), iso-C15 : 0 (14.0 %), summed feature 9 (11.8 %, comprising 10-methyl C16 : 0 and/or iso-C17 : 1ω9c), iso-C17 : 0 3-OH (11.8 %), iso-C16 : 0 (7.4 %), C17 : 1ω6c (6.9 %) and anteiso-C15 : 0 (5.1 %). The major polar lipids were phosphatidylethanolamine, four unidentified lipids, an unidentified aminolipid, an unidentified aminophospholipid and an unidentified glycolipid. The DNA G+C content of strain R17H11T was 38.6 mol%. On the basis of the phylogenetic, physiological and chemotaxonomic characteristics, strain R17H11T represents a novel species in the genus Gramella, for which the name Gramellaantarctica sp. nov. is proposed. The type strain of the novel species is R17H11T (=GDMCC 1.1208T=KCTC 52925T).