On the role of Rossby wave breaking in quasi‐biennial odulation of the stratospheric polar vortex

The boreal‐winter stratospheric polar vortex is more disturbed when the quasi‐biennial oscillation (QBO) in the lower stratosphere is in its easterly phase (eQBO), and more stable during the westerly phase (wQBO). This so‐called “Holton‐Tan effect” (HTE) is known to involve Rossby waves (RWs) but the details remain obscure. This tropical‐extratropical connection is re‐examined in an attempt to explain its intra‐seasonal variation and its relation to Rossby wave breaking (RWB). Reanalyses in isentropic coordinates from the National Center for Environmental Prediction Climate Forecast System for the 1979 – 2017 period are used to evaluate the relevant features of RWB in the context of waveguide, wave mean‐flow interaction, and the QBO‐induced meridional circulation. During eQBO, the net extratropical wave forcing is enhanced in early winter with ~25% increase in upward propagating PRWs of zonal wavenumber 1 (wave‐1). RWB is also enhanced in the lower stratosphere, characterized by convergent anomalies in the subtropics and at high‐latitudes and strengthened waveguide in between at 20‐40°N, 350‐650 K. In late winter, RWB leads to finite amplitude growth, which hinders upward propagating PRWs of zonal wavenumber 2 and 3 (wave‐2‐3). During wQBO, RWB in association with wave‐2‐3 is enhanced in the upper stratosphere. Wave absorption/mixing in the surf zone reinforces a stable polar vortex in early to middle winter. A poleward confinement of extratropical waveguide in the upper stratosphere forces RWB to extend downward around January. A strengthening of upward propagating wave‐2‐3 follows and the polar‐vortex response switches from reinforcement to disturbance around February, thus a sign reversal of the HTE in late winter

On the role of Rossby wave breaking in the quasi-biennial modulation of the stratospheric polar vortex during boreal winter

The boreal‐winter stratospheric polar vortex is more disturbed when the quasi‐biennial oscillation (QBO) in the lower stratosphere is in its easterly phase (eQBO), and more stable during the westerly phase (wQBO). This so‐called “Holton‐Tan effect” (HTE) is known to involve Rossby waves (RWs) but the details remain obscure. This tropical‐extratropical connection is re‐examined in an attempt to explain its intra‐seasonal variation and its relation to Rossby wave breaking (RWB). Reanalyses in isentropic coordinates from the National Center for Environmental Prediction Climate Forecast System for the 1979 – 2017 period are used to evaluate the relevant features of RWB in the context of waveguide, wave mean‐flow interaction, and the QBO‐induced meridional circulation. During eQBO, the net extratropical wave forcing is enhanced in early winter with ~25% increase in upward propagating PRWs of zonal wavenumber 1 (wave‐1). RWB is also enhanced in the lower stratosphere, characterized by convergent anomalies in the subtropics and at high‐latitudes and strengthened waveguide in between at 20‐40°N, 350‐650 K. In late winter, RWB leads to finite amplitude growth, which hinders upward propagating PRWs of zonal wavenumber 2 and 3 (wave‐2‐3). During wQBO, RWB in association with wave‐2‐3 is enhanced in the upper stratosphere. Wave absorption/mixing in the surf zone reinforces a stable polar vortex in early to middle winter. A poleward confinement of extratropical waveguide in the upper stratosphere forces RWB to extend downward around January. A strengthening of upward propagating wave‐2‐3 follows and the polar‐vortex response switches from reinforcement to disturbance around February, thus a sign reversal of the HTE in late winter.</br

Significant Productivity Improvement of the Baculovirus Expression Vector System by Engineering a Novel Expression Cassette

Here we describe the development of a baculovirus vector expression cassette containing rearranged baculovirus-derived genetic regulatory elements. This newly designed expression cassette conferred significant production improvements to the baculovirus expression vector system (BEVS), including prolonged cell integrity after infection, improved protein integrity, and around 4-fold increase in recombinant protein production yields in insect cells with respect to a standard baculovirus vector. The expression cassette consisted of a cDNA encoding for the baculovirus transactivation factors IE1 and IE0, expressed under the control of the polyhedrin promoter, and a homologous repeated transcription enhancer sequence operatively cis-linked to the p10 promoter or to chimeric promoters containing p10. The prolonged cell integrity observed in cells infected by baculoviruses harbouring the novel expression cassette reduced the characteristic proteolysis and aberrant forms frequently found in baculovirus-derived recombinant proteins. The new expression cassette developed here has the potential to significantly improve the productivity of the BEVS

Mixotrophic haptophytes are key bacterial grazers in oligotrophic coastal waters

13 pages, 6 figures, 1 tableGrazing rate estimates indicate that approximately half of the bacterivory in oligotrophic oceans is due to mixotrophic flagellates (MFs). However, most estimations have considered algae as a single group. Here we aimed at opening the black-box of the phytoflagellates (PFs) <20 μm. Haptophytes, chlorophytes, cryptophytes and pigmented dinoflagellates were identified using fluorescent in situ hybridization or by standard 4′,6-diamidino-2- phenylindole staining. Their fluctuations in abundance, cell size, biomass and bacterivory rates were measured through an annual cycle in an oligotrophic coastal system. On average, we were able to assign to these groups: 37% of the total pico-PFs and 65% of the nano-PFs composition. Chlorophytes were mostly picoplanktonic and they never ingested fluorescently labeled bacteria. About 50% of the PF <20 μm biomass was represented by mixotrophic algae. Pigmented dinoflagellates were the least abundant group with little impact on bacterioplankton. Cryptophytes were quantitatively important during the coldest periods and explained about 4% of total bacterivory. Haptophytes were the most important mixotrophic group: (i) they were mostly represented by cells 3-5 μm in size present year-round; (ii) cell-specific grazing rates were comparable to those of other bacterivorous non-photosynthetic organisms, regardless of the in situ nutrient availability conditions; (iii) these organisms could acquire a significant portion of their carbon by ingesting bacteria; and (iv) haptophytes explained on average 40% of the bacterivory exerted by MFs and were responsible for 9-27% of total bacterivory at this site. Our results, when considered alongside the widespread distribution of haptophytes in the ocean, indicate that they have a key role as bacterivores in marine ecosystems. © 2014 International Society for Microbial Ecology All rights reservedThis study was supported by EU project BASICS (EVK3-CT-2002-00078) and a post-doctoral fellowship of the former MECD (SB2001-0166). It was also partially funded by MEC projects ESTRAMAR (CTM2004-12631/MAR), GENmMAR (CTM2004-02586/MAR) and FLAME (CGL2010-16304, MICINN), and by the Spanish-Argentina project PROBA (2007AR0018, CSIC). FN was supported by the Marie-Curie fellowship ESUMAST (MEIF-CT-2005-025000)Peer Reviewe

Genetic modification of a baculovirus vector for increased expression in insect cells

Generating large amounts of recombinant protein in transgenic animals is often challenging and has a number of drawbacks compared to cell culture systems. The baculovirus expression vector system (BEVS) uses virus-infected insect cells to produce recombinant proteins to high levels, and these are usually processed in a similar way to the native protein. Interestingly, since the development of the BEVS, the virus most often used (Autographa californica multi-nucleopolyhedovirus; AcMNPV) has been little altered genetically from its wild-type parental virus. In this study, we modified the AcMNPV genome in an attempt to improve recombinant protein yield, by deleting genes that are nonessential in cell culture. We deleted the p26, p10 and p74 genes from the virus genome, replacing them with an antibiotic selection cassette, allowing us to isolate recombinants. We screened and identified recombinant viruses by restriction enzyme analysis, PCR and Western blot. Cell viability analysis showed that the deletions did not improve the viability of infected cells, compared to non-deletion viruses. However, expression studies showed that recombinant protein levels for the deletion viruses were significantly higher than the expression levels of nondeletion viruses. These results confirm that there is still great potential for improving the BEVS, further increasing recombinant protein expression yields and stability in insect cells

Sol-gel based optically active phenolphthalein encapsulated nanomatrices for sensing application

In this work, synthesis and characterization of phenolphthalein-immobilized titania (T-phph) and silica–titania (ST-phph) nanomatrix is reported. The thin films are deposited by sol–gel method at low temperature. The effect of host–guest chemistry in matrices, on the surface structures, optical and sensing activity of the resultant thin films is studied. The phenolphthalein-immobilized fabricated nanoparticles/nanomatrices are analyzed by field emission scanning electron microscope, energy-dispersive X-ray spectroscopy, atomic-force microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, surface analysis, thermogravimetric analysis, and UV–Vis spectroscopy. Thermally stable and high surface area homogeneous nanoparticles, containing nanocrystalline anatase phase with low refractive index (1.58), low roughness (5.5 nm), and high transparency (95 %) are obtained for phenolphthalein-immobilized ST-phph nanomatrix. Moreover, smaller nanoparticles (56–121 nm) with good incorporation of dye and good response of sensing are obtained. The sensor response is optimized at pH 12 with 10.1 pKa value at 555 nm. Graphical Abstract: [Figure not available: see fulltext