Search

Objective To investigate the effects of metformin(Met) on the proliferation of pancreatic cancer cells under different glucose concentration culture conditions, and to find the potential role of miR-139-5p in the process. Methods PANC-1 cells were treated with different concentrations of metformin(0/5/10/20 mmol/L) in 25 mmol/L(high-glucose group,HG) or 5 mmol/L(normal-glucose group,NG) glucose culture, cell proliferation, apoptosis, migration and cell cycle were detected after 48 h. The expression of miR-139-5p was quantitatively detected by RT-qPCR, and the miR-139-5p mimics were transfected into PANC-1 cells to clarify the role of miR-139-5p. Results Metformin inhibited the proliferation, promoted apoptosis, and induced S phase and G2/M phase arrest of PANC-1 cells under in high glucose and normal glucose culture conditions, and its anti-proliferation and pro-apoptosis effects were more significant in the normal glucose groups. The expression of miR-139-5p was up-regulated by metformin treatment in normal but not in high glucose culture. Further studies showed that miR-139-5p mimics inhibited of PANC-1 cells proliferation without metformin pre-incubation and enhanced the anti-proliferation effect of 5 mmol/L metformin. The pro-apoptotic effect of 10 mmol/L metformin in normal glucose culture conditions. Conclusions In normal-glucose culture conditions, metformin can inhibit proliferation, induce apoptosis and cell cycle arrest of PANC-1 cells more significantly than in higher-glucose culture, which may be partly related to the up-regulation of miR-139-5p.

In this review, the research reports on the dispersion processes of carbon nanotubes (CNTs) in aqueous cementitious materials are intensively introduced and summarized. The main processes for the CNTs dispersion in aqueous systems include high shear emulsification, ultrasonic treatment, covalent modification, and non-covalent modification. The influences of various factors on the dispersity of CNTs are evaluated, and the pros and cons of dispersion processes of CNTs are analyzed, along with the dispersion mechanism of CNTs in aqueous materials. Several novel techniques are also introduced, including arc thermal excitation and electromagnetic field-induced method, etc. In addition, the challenges when CNTs dispersion are further involved in cementitious alkali pore solution and the improvement means are also described in detail. And, the direct dispersion process (in situ growth process) of CNTs in cementitious materials has also been discussed in depth.

Microbial proton-pump rhodopsin (PPR)-based phototrophy, a light-harvesting mechanism different from chlorophyll-based photosystems, may contribute significantly to solar energy entry into the marine ecosystem. PPR transforms solar energy into cellular energy that is used for various metabolic processes in the cells or flagellar movement. Although rhodopsins or their encoding genes have been documented in a wide phylogenetic range of cultured dinoflagellates, information is limited about how widespread and how spatiotemporally dynamical dinoflagellate PPR (DiPPR) are in natural marine ecosystems. In this study, we investigated DiPPR in Long Island Sound (LIS), a temperate estuary of the Atlantic Ocean between Connecticut and Long Island, New York, USA. We isolated six novel full-length dinoflagellate proton-pump rhodopsin cDNAs, expanding the DiPPR database that is crucial to PPR research. Based on these new sequences and existing sequences of DiPPR, we designed primers and conducted quantitative PCR and sequencing to determine the abundance and diversity of DiPPR genes spatially and temporally throughout a year in the water samples collected from LIS. DiPPR genes were found year-round and throughout LIS but with higher abundances in the eutrophic Western Sound and in April and July. The gene diversity data suggest that there are at least five distinct rhodopsin-harboring groups of dinoflagellates throughout the year. The abundance of DiPPR genes, measured as copy number per mL of seawater, appeared not to be influenced by water temperature or nitrogen nutrient concentration but exhibited weak negative correlations with orthophosphate concentration and salinity and a positive correlation with the abundance of DiPPR-harboring dinoflagellates. This first quantitative profiling of PPR in natural plankton reveals the prevalence and dynamics of this plastid-independent photoenergy harvesting mechanism in a temperate estuary and provides efficient DiPPR primers potentially useful for future research. Furthermore, this study shed light on the potential role of DiPPR in phosphor nutrition and dinoflagellate population, which warrants further studies. [ABSTRACT FROM AUTHOR]

Typical (peridinin-containing) dinoflagellates possess plastid genomes composed of small plasmids named "minicircles". Despite the ecological importance of dinoflagellate photosynthesis in corals and marine ecosystems, the structural characteristics, replication dynamics, and evolutionary forcing of dinoflagellate plastid genomes remain poorly understood. Here, we sequenced the plastid genome of the symbiodiniacean species Fugacium kawagutii and conducted comparative analyses. We identified psbT -coding minicircles, features previously not found in Symbiodiniaceae. The copy number of F. kawagutii minicircles showed a strong diel dynamics, changing between 3.89 and 34.3 copies/cell and peaking in mid-light period. We found that F. kawagutii minicircles are the shortest among all dinoflagellates examined to date. Besides, the core regions of the minicircles are highly conserved within genus in Symbiodiniaceae. Furthermore, the codon usage bias of the plastid genomes in Heterocapsaceae, Amphidiniaceae, and Prorocentraceae species are greatly influenced by selection pressure, and in Pyrocystaceae, Symbiodiniaceae, Peridiniaceae, and Ceratiaceae species are influenced by both natural selection pressure and mutation pressure, indicating a family-level distinction in codon usage evolution in dinoflagellates. Phylogenetic analysis using 12 plastid-encoded proteins and five nucleus-encoded plastid proteins revealed accelerated evolution trend of both plastid- and nucleus-encoded plastid proteins in peridinin- and fucoxanthin-dinoflagellate plastids compared to plastid proteins of nondinoflagellate algae. These findings shed new light on the structure and evolution of plastid genomes in dinoflagellates, which will facilitate further studies on the evolutionary forcing and function of the diverse dinoflagellate plastids. The accelerated evolution documented here suggests plastid-encoded sequences are potentially useful for resolving closely related dinoflagellates. [ABSTRACT FROM AUTHOR]

We demonstrate automated adaptation, and stabilization of a silicon photonic wavelength-division multiplexing (WDM), polarization-independent receiver. A two-channel, tunable WDM polarization-independent receiver is designed, and used to demonstrate automated WDM polarization control. Using a control algorithm based on Barzilai, and Borwein's two-point step size gradient descent method, we realize automated polarization adaptation, and wavelength stabilization for two arbitrarily polarized input data streams. 10 Gb/s on-off keying, and 20 Gb/s pulse-amplitude modulation 4-level formats are generated as the high-speed input data streams. In addition, we implement a long-duration experiment, in which we measure the bit-error-ratio for continuously varying polarization states, and changing chip temperatures. The experimental results show that, with the automated control, the WDM polarization-independent receiver can adapt, stabilize, and track the arbitrary input polarization states from a standard optical fiber into the transverse electric mode of a silicon waveguide, and simultaneously stabilize the transmitted wavelength channels at various chip temperatures. We also show how the presented WDM polarization-independent receiver scales with N channels, and propose an improved design for large-scale WDM applications. [ABSTRACT FROM AUTHOR]

We experimentally demonstrate compact broadband directional couplers using subwavelength gratings for silicon-on-insulator wafers with silicon layers of 220 nm. The dispersion properties of the optical modes are engineered using subwavelength gratings, which allow broadband operation. Finite-difference time-domain (FDTD)-based band structure calculations, with significantly reduced simulation time, were used to analyze the design, which included both the structure and material dispersions. Compact broadband direction couplers, with device lengths shorter than 14 \mu\textm, which cover a bandwidth of 100 nm for power splitting ratios of 50/50, 40/60, 30/70, and 20/80, are designed and fabricated for the fundamental transverse electric mode with a central operating wavelength of 1550 nm. [ABSTRACT FROM PUBLISHER]

A ring resonator based 4 channel wavelength division multiplexing (WDM) receiver with polarization diversity is demonstrated at 10 Gb/s per channel. By forming a waveguide loop between the two output ports of a polarization splitter-rotator (PSR), the input signals in the quasi-transverse-electric (quasi-TE) and the quasi-transverse-magnetic (quasi-TM) polarizations can be demultiplexed by the same set of ring resonator filters, thus reducing the number of required channel control circuits by half compared to methods which process the two polarizations individually. Large signal measurement results indicate that the design can tolerate a signal delay of up to 30% of the unit interval (UI) between the two polarizations, which implies that compensating for manufacturing variability with optical delay lines on chip is not necessary for a robust operation. The inter-channel crosstalk is found negligible down to 0.4nm (50 GHz) spacing, at which point the adjacent channel isolation is 17 dB, proving the design's compatibility for dense WDM application.