The adaptation of Arctic phytoplankton to low light and salinity in Kongsfjorden (Spitsbergen)

The basic environmental variables and adaptability of phytoplankton communities to low light and salinity were studied using incubation experiments in Kongsfjorden, a high Arctic fjord of Spitsbergen, in late summer 2006. Chlorophyll a concentrations were steady or decreased slightly in darkness after one day or one week incubation. Chlorophyll a concentrations showed an initial decline when exposed to natural light after one week incubation in darkness, and then increased significantly. In a salinity experiment, the maximal growth rate was observed at a dilution ratio of 10%, however, higher dilution ratios (≥40%) had an obvious negative effect on phytoplankton growth. We suggest that the phytoplankton communities in fjords in late summer are darkness adapted, and the inflow of glacial melt water is favorable for phytoplankton growth in the outer fjords where the influence of freshwater is limited

Effects of Grain Orientation on Stress State near Grain Boundary of Austenitic Stainless Steel Bicrystals

The stress state at the crack tip of structural components in nuclear power plants used in the SCC quantitative prediction models is based on the assumption that the polycrystalline material is isotropic and homogeneous at present. However, the crystals in polycrystalline materials are anisotropic with different orientations, which would induce a nonuniform stress to cause the initiation and propagation of SCC. By using a finite element method, the elastic responses of anisotropic behaviors of austenitic stainless steel bicrystals are studied. The results indicate that the stress distribution near GBs depends strongly on the crystal orientation. A larger Mises stress concentration exists on the GB with larger stiffness along the load direction. The Mises stress difference is higher in the bicrystal with bigger elastic modulus difference of two neighboring grains along the tensile axis. In the bicrystal with GB perpendicular to the tensile axis, the grain orientation has little effects on the Mises stress far from the GB in both grains. The strain inconsistency in bicrystals is affected by the mismatch of two neighboring grains. The larger the elastic modulus differences between two neighboring grains caused by misorientation, the larger the strain inconsistency in the bicrystal

Bilateral striatal necrosis due to homoplasmic mitochondrial 3697G\u3eA mutation presents with incomplete penetrance and sex bias

© 2019 The Authors. Molecular Genetics & Genomic Medicine published by Wiley Periodicals, Inc. Background: Heteroplasmic mitochondrial 3697G\u3eA mutation has been associated with leber hereditary optic neuropathy (LHON), mitochondrial encephalopathy, lactic acidosis and stroke-like episodes (MELAS), and LHON/MELAS overlap syndrome. However, homoplasmic m.3697G\u3eA mutation was only found in a family with Leigh syndrome, and the phenotype and pathogenicity of this homoplasmic mutation still need to be investigated in new patients. Methods: The clinical interviews were conducted in 12 individuals from a multiple-generation inherited family. Mutations were screened through exome next-generation sequencing and subsequently confirmed by PCR-restriction fragment length polymorphism. Mitochondrial complex activities and ATP production rate were measured by biochemical analysis. Results: The male offspring with bilateral striatal necrosis (BSN) were characterized by severe spastic dystonia and complete penetrance, while the female offspring presented with mild symptom and low penetrance. All offspring carried homoplasmic mutation of NC_012920.1: m.3697G\u3eA, p.(Gly131Ser). Biochemical analysis revealed an isolated defect of complex I, but the magnitude of the defect was higher in the male patients than that in the female ones. The ATP production rate also exhibited a similar pattern. However, no possible modifier genes on the X chromosome were identified. Conclusion: Homoplasmic m.3697G\u3eA mutation could be associated with BSN, which expanded the clinical spectrum of m.3697G\u3eA. Our preliminary investigations had not found the underlying modifiers to support the double hit hypothesis, while the high level of estrogens in the female patients might exert a potential compensatory effect on mutant cell metabolism

Characteristics and variations of the picophytoplankton community in the Arctic Ocean

Picophytoplankton are responsible for much of the carbon fixation process in the Arctic Ocean, and they play an important role in active microbial food webs. The climate of the Arctic Ocean has changed in recent years, and picophytoplankton, as the most vulnerable part of the high-latitude pelagic ecosystem, have been the focus of an increasing number of scientific studies. This paper reviews and summarizes research on the characteristics of picophytoplankton in the Arctic Ocean, including their abundance, biomass, spatial distribution, seasonal variation, community structure, and factors influencing their growth. The impact of climate change on the Arctic Ocean picophytoplankton community is discussed, and future research directions are considered

Spatial distribution of pico- and nano-phytoplankton and bacteria in the Chukchi Sea in relation to water masses

We evaluated the relationships between water masses and pico- and nano-phytoplankton and bacterial abundance in the Chukchi Sea. The abundance of picoplankton ranged from 0.01 × 103 cells∙mL-1 (100 m, station R05) to 2.21 × 103 cells∙mL-1 (10 m, station R05) and that of nanoplankton ranged from 0.03 × 103 cells∙mL-1 (100 m, station R07) to 2.21 × 104 cells∙mL-1 (10 m, station R05). The lowest abundance of bacteria in the whole water column (0.21 × 106 cells∙mL-1) was at 100 m at station R17, and the highest (9.61 × 106 cells∙mL-1) was at 10 m at station R09. Melting sea ice affected the physical characteristics of the Chukchi Sea by reducing salinity of the surface mixed layer, resulting in greater hydrodynamic stability of the water column. These changes were accompanied by increased bacterial abundance. The warm Pacific water brought nutrients into the Chukchi Sea, resulting in greater abundance of bacteria and nano-phytoplankton in the Chukchi Sea than in other regions of the Arctic Ocean. However, the abundance of pico-phytoplankton, which was related to chlorophyll a concentration, was higher in Anadyr water than in the other two water masses. The structures of pico- and nanoplankton communities coupled with the water masses in the Chukchi Sea can serve as indicators of the inflow of warm Pacific water into the Chukchi Sea

Stanniocalcin-1 promotes tumor angiogenesis through up-regulation of VEGF in gastric cancer cells

<p>Abstract</p> <p>Background</p> <p>Stanniocalcin-1(STC-1) is up-regulated in several cancers including gastric cancer. Evidences suggest that STC-1 is associated with carcinogenesis and angiogenic process. However, it is unclear on the exact role for STC-1 in inducing angiogenesis and tumorigeneisis.</p> <p>Method</p> <p>BGC/STC cells (high-expression of STC-1) and BGC/shSTC cells (low- expression of STC-1) were constructed to investigate the effect of STC-1 on the xenograft tumor growth and angiogenesis <it>in vitro </it>and <it>in vivo</it>. ELISA assay was used to detect the expression of vascular endothelial growth factor (VEGF) in the supernatants. Neutralizing antibody was used to inhibit VEGF expression in supernatants. The expression of phosphorylated -PKCβII, phosphorylated -ERK1/2 and phosphorylated -P38 in the BGC treated with STC-1protein was detected by western blot.</p> <p>Results</p> <p>STC-1 could promote angiogenesis <it>in vitro </it>and <it>in vivo</it>, and the angiogenesis was consistent with VEGF expression <it>in vitro</it>. Inhibition of VEGF expression in supernatants with neutralizing antibody markedly abolished angiogenesis induced by STC-1 <it>in vitro</it>. The process of STC-1-regulated VEGF expression was mediated via PKCβII and ERK1/2.</p> <p>Conclusions</p> <p>STC-1 promotes the expression of VEGF depended on the activation of PKCβII and ERK1/2 pathways. VEGF subsequently enhances tumor angiogenesis which in turn promotes the gastric tumor growth.</p