Langmuir supercells on the middle shelf of the South Atlantic Bight: 1. Cell structure

Langmuir circulation cells extending through entire water columns exert a profound influence on sediment transport on shallow shelves, hence their designation as Langmuir Supercells (LSs) upon discovery in 2004 in water of 15 m depth at the Long-Term Ecosystem Observatory (LEO) off New Jersey (United States). Until now, similar high-frequency, full water column measurements of turbulent velocities and density fields have not been reported from significantly deeper continental shelf environments. Such deeper measurements are needed to determine whether LSs exist to influence sediment transport outside the inner shelf. In this article, that deficiency is addressed, using measurements from a midshelf location in the South Atlantic Bight. These data indicate that LSs form during high wind and wave forcing in water of 26 m depth and are thus capable of affecting sediment transport over more than about half of the area of this wide, shallow shelf. Relative to those at LEO, the LSs reported here are less organized and more temporally variable despite similar magnitude forcing. Possible causes of cell weakness and variability are considered

Anatomy of a Langmuir supercell event

Langmuir supercells (LS), which are Langmuir circulations (LC) extending over full water column depth during storms and revealed by high water column backscatter from surface-origin microbubbles and bottom-origin sediment, were discovered in 2003 during several months of measurements in 15 m of water near the coast of New Jersey. Both the structures themselves and the specific forcing conditions under which they occur have been documented elsewhere. This paper provides an account of the broader oceanographic setting of supercell events, focusing on conditions at the start and end. The start of events is associated with the presence of surface waves of intermediate type that “feel bottom” with amplitudes sufficiently large to resuspend sediment and achievement of three conditions for full-depth LC: an unstratified water column, La \u3c ∼0.3 and |Ra| \u3c 105, where Ra and La are dimensionless parameters derived from scaling of the wave-averaged momentum equation. Event cessation is associated with failure of one of the latter two conditions or the reappearance of stratification. There is no fixed order in which conditions necessary for full-depth LC are met or fail. Comparison with data from a deeper site off Georgia suggests that coherent full-depth Langmuir circulations will not generally be observed in unstratified water columns much deeper than 25–30 m, a depth determined primarily by the wavelength of surface waves generated by typical storms. We also document two features of LC acting in the surface layer of the stratified water column that existed prior to onset of the prototype LS event. First, LC confined to the surface layer generated first mode internal waves with frequency that of the stratified interior. Secondly, active surface layer LC did not act efficiently as direct agents of mixed layer deepening, which occurred primarily in two separate episodes of Richardson number lowered by increased shear. Instead, as a result of quasi-organized structure and enhanced vertical penetration relative to stress-driven turbulence, the primary role of LC may be to increase efficiency of momentum transfer to the surface layer, enhancing surface layer acceleration and contributing to onset of the shear instability that does deepen the surface layer

Increase in DNA vaccine efficacy by virosome delivery and co-expression of a cytolytic protein

The potential of DNA vaccines has not been realised due to suboptimal delivery, poor antigen expression and the lack of localised inflammation, essential for antigen presentation and an effective immune response to the immunogen. Initially, we examined the delivery of a DNA vaccine encoding a model antigen, luciferase (LUC), to the respiratory tract of mice by encapsulation in a virosome. Virosomes that incorporated influenza virus haemagglutinin effectively delivered DNA to cells in the mouse respiratory tract and resulted in antigen expression and systemic and mucosal immune responses to the immunogen after an intranasal (IN) prime/intradermal (ID) boost regimen, whereas a multidose ID regimen only generated systemic immunity. We also examined systemic immune responses to LUC after ID vaccination with a DNA vaccine, which also encoded one of the several cytolytic or toxic proteins. Although the herpes simplex virus thymidine kinase, in the presence of the prodrug, ganciclovir, resulted in cell death, this failed to increase the humoral or cell-mediated immune responses. In contrast, the co-expression of LUC with the rotavirus non-structural protein 4 (NSP4) protein or a mutant form of mouse perforin, proteins which are directly cytolytic, resulted in increased LUC-specific humoral and cell-mediated immunity. On the other hand, co-expression of LUC with diphtheria toxin subunit A or overexpression of perforin or NSP4 resulted in a lower level of immunity. In summary, the efficacy of DNA vaccines can be improved by targeted IN delivery of DNA or by the induction of cell death in vaccine-targeted cells after ID delivery.Tessa Gargett, Branka Grubor-Bauk, Darren Miller, Tamsin Garrod, Stanley Yu, Steve Wesselingh, Andreas Suhrbier, and Eric J Gowan

Report on the Second NLG Challenge on Generating Instructions in Virtual Environments (GIVE-2)

We describe the second installment of the Challenge on Generating Instructions in Virtual Environments (GIVE-2), a shared task for the NLG community which took place in 2009-10. We evaluated seven NLG systems by connecting them to 1825 users over the Internet, and report the results of this evaluation in terms of objective and subjective measures

Linking mixing processes and climate variability to the heat content distribution of the Eastern Mediterranean abyss

The heat contained in the ocean (OHC) dominates the Earth’s energy budget and hence represents a fundamental parameter for understanding climate changes. However, paucity of observational data hampers our knowledge on OHC variability, particularly in abyssal areas. Here, we analyze water characteristics, observed during the last three decades in the abyssal Ionian Sea (Eastern Mediterranean), where two competing convective sources of bottom water exist. We find a heat storage of ~1.6 W/m2– twice that assessed globally in the same period – exceptionally well-spread throughout the local abyssal layers. Such an OHC accumulation stems from progressive warming and salinification of the Eastern Mediterranean, producing warmer near-bottom waters. We analyze a new process that involves convectively-generated waters reaching the abyss as well as the triggering of a diapycnal mixing due to rough bathymetry, which brings to a warming and thickening of the bottom layer, also influencing water-column potential vorticity. This may affect the prevailing circulation, altering the local cyclonic/anticyclonic long-term variability and hence precondition future water-masses formation and the redistribution of heat along the entire water-column

The response of the upper ocean to solar heating. I: The mixed layer

The results of two earlier papers on convection in the mixed layer and on the solar heating profile are here introduced into a one-dimensional model in order to investigate the following consequences of the daily cycle of solar heating in the upper ocean: 1. the daytime convection depth becomes less than the turbocline depth; 2. the convective power supply to turbulence in the mixed layer is reduced; 3. the mixed layer below the convection layer becomes stably stratified; 4. the depth of the turbocline is reduced, leaving a diurnal thermocline between it and the top of the seasonal thermocline; 5. the heat content and potential energy of the diurnal and seasonal thermoclines are increased, slowing down the subsequent nocturnal descent of the turbocline. These diurnal changes are illustrated by integrating a one-dimensional model forced by the astronomical cycle of solar heating and seasonal variation of surface meteorology derived from Bunker's climatology. The model is integrated for 18 months to show the seasonal modulation of the diurnal cycle. Nocturnal convection plays a dominant role. The convection depth closely follows the thermal compensation depth during the day when they are less than the turbocline depth. Integrating the model with a 24-hour time step leads to large errors in the seasonal variation of mixed layer temperature and depth, and in the source term of isopycnic potential vorticity. The errors are reduced by using two time steps per day, one for the daytime when convection is quenched, the other for the night when it is active. A novel parametrization based on tuning the daily equivalent solar elevation to surface temperature further reduces the error. This parametrization is used to investigate the sensitivity of the seasonal cycles of mixed layer depth and temperature to: (1) seasonality in the surface fluxes; (2) systematic changes in the net annual solar heating; (3) random changes in the seasonal cycles of solar heating induced (i) monthly and (ii) daily. The sensitivity to uncertainty in seawater turbidity is investigated in the same way. The profile of isopycnic potential vorticity subducted into the thermocline depends on the vernal correlation of mixed layer depth and density, so gyre circulation is sensitive to solar heating in spring

Cancer-initiating cells derived from established cervical cell lines exhibit stem-cell markers and increased radioresistance

<p>Abstract</p> <p>Background</p> <p>Cancer-initiating cells (CICs) are proposed to be responsible for the generation of metastasis and resistance to therapy. Accumulating evidences indicates CICs are found among different human cancers and cell lines derived from them. Few studies address the characteristics of CICs in cervical cancer. We identify biological features of CICs from four of the best-know human cell lines from uterine cervix tumors. (HeLa, SiHa, Ca Ski, C-4 I).</p> <p>Methods</p> <p>Cells were cultured as spheres under stem-cell conditions. Flow cytometry was used to detect expression of CD34, CD49f and CD133 antigens and Hoechst 33342 staining to identify side population (SP). Magnetic and fluorescence-activated cell sorting was applied to enrich and purify populations used to evaluate tumorigenicity in nude mice. cDNA microarray analysis and <it>in vitro </it>radioresistance assay were carried out under standard conditions.</p> <p>Results</p> <p>CICs, enriched as spheroids, were capable to generate reproducible tumor phenotypes in nu-nu mice and serial propagation. Injection of 1 × 10³dissociated spheroid cells induced tumors in the majority of animals, whereas injection of 1 × 10⁵monolayer cells remained nontumorigenic. Sphere-derived CICs expressed CD49f surface marker. Gene profiling analysis of HeLa and SiHa spheroid cells showed up-regulation of CICs markers characteristic of the female reproductive system. Importantly, epithelial to mesenchymal (EMT) transition-associated markers were found highly expressed in spheroid cells. More importantly, gene expression analysis indicated that genes required for radioresistance were also up-regulated, including components of the double-strand break (DSB) DNA repair machinery and the metabolism of reactive oxygen species (ROS). Dose-dependent radiation assay indicated indeed that CICs-enriched populations exhibit an increased resistance to ionizing radiation (IR).</p> <p>Conclusions</p> <p>We characterized a self-renewing subpopulation of CICs found among four well known human cancer-derived cell lines (HeLa, SiHa, Ca Ski and C-4 I) and found that they express characteristic markers of stem cell, EMT and radioresistance. The fact that CICs demonstrated a higher degree of resistance to radiation than differentiated cells suggests that specific detection and targeting of CICs could be highly valuable for the therapy of tumors from the uterine cervix.</p

Activation of transcription factors by extracellular nucleotides in immune and related cell types

Extracellular nucleotides, acting through P2 receptors, can regulate gene expression via intracellular signaling pathways that control the activity of transcription factors. Relatively little is known about the activation of transcription factors by nucleotides in immune cells. The NF-κB family of transcription factors is critical for many immune and inflammatory responses. Nucleotides released from damaged or stressed cells can act alone through certain P2 receptors to alter NF-κB activity or they can enhance responses induced by pathogen-associated molecules such as LPS. Nucleotides have also been shown to regulate the activity of other transcription factors (AP-1, NFAT, CREB and STAT) in immune and related cell types. Here, we provide an overview of transcription factors shown to be activated by nucleotides in immune cells, and describe what is known about their mechanisms of activation and potential functions. Furthermore, we propose areas for future work in this new and expanding field