The Arabidopsis thaliana trehalase is a plasma membrane-bound enzyme with extracellular activity

The lack of trehalose accumulation in most plant species has been partly attributed to the presence of an active trehalase. Although trehalose synthesis enzymes are thought to be cytosolic, and previous studies have indicated that trehalase activity is extracellular, the exact location of the enzyme has not yet been established in plant cell. We present evidence that the yet uncharacterised full-length Arabidopsis trehalase is a plasma membrane-bound protein, probably anchored to the membrane through a predicted N-terminal membrane spanning domain. The full-length AtTRE1, when expressed in yeast can functionally substitute for the extracellularly active trehalase Ath1p, by sustaining the growth of an ath1 null mutant strain on trehalose and at pH 4.8. We further demonstrate that AtTRE1 expressed in yeast is plasma membrane-bound as in plant cell. In light of these findings, the regulation of plant cell endogenous trehalose by trehalase is discussed.     

Abundance and Distribution of Sperm Whales in the Canary Islands: Can Sperm Whales in the Archipelago Sustain the Current Level of Ship-Strike Mortalities?

Sperm whales are present in the Canary Islands year-round, suggesting that the archipelago is an important area for this species in the North Atlantic. However, the area experiences one of the highest reported rates of sperm whale ship-strike in the world. Here we investigate if the number of sperm whales found in the archipelago can sustain the current rate of ship-strike mortality. The results of this study may also have implications for offshore areas where concentrations of sperm whales may coincide with high densities of ship traffic, but where ship-strikes may be undocumented. The absolute abundance of sperm whales in an area of 52933 km², covering the territorial waters of the Canary Islands, was estimated from 2668 km of acoustic line-transect survey using Distance sampling analysis. Data on sperm whale diving and acoustic behaviour, obtained from bio-logging, were used to calculate g(0) = 0.92, this is less than one because of occasional extended periods when whales do not echolocate. This resulted in an absolute abundance estimate of 224 sperm whales (95% log-normal CI 120–418) within the survey area. The recruitment capability of this number of whales, some 2.5 whales per year, is likely to be exceeded by the current ship-strike mortality rate. Furthermore, we found areas of higher whale density within the archipelago, many coincident with those previously described, suggesting that these are important habitats for females and immature animals inhabiting the archipelago. Some of these areas are crossed by active shipping lanes increasing the risk of ship-strikes. Given the philopatry in female sperm whales, replacement of impacted whales might be limited. Therefore, the application of mitigation measures to reduce the ship-strike mortality rate seems essential for the conservation of sperm whales in the Canary Islands.     

An essential role of STIM1, Orai1, and S100A8-A9 proteins for Ca2+ signaling and FcγR-mediated phagosomal oxidative activity

Phagocytosis is a process of innate immunity that allows for the enclosure of pathogens within the phagosome and their subsequent destruction through the production of reactive oxygen species (ROS). Although these processes have been associated with increases of intracellular Ca(2+) concentrations, the mechanisms by which Ca(2+) could regulate the different phases of phagocytosis remain unknown. The aim of this study was to investigate the Ca(2+) signaling pathways involved in the regulation of FcγRs-induced phagocytosis. Our work focuses on IgG-opsonized zymosan internalization and phagosomal ROS production in DMSO-differentiated HL-60 cells and neutrophils. We found that chelation of intracellular Ca(2+) by BAPTA or emptying of the intracellular Ca(2+) store by thapsigargin reduced the efficiency of zymosan internalization. Using an small interfering RNA strategy, our data establish that the observed Ca(2+) release occurs through two isoforms of inositol 1,4,5-triphosphate receptors, ITPR1 and ITPR3. In addition, we provide evidence that phagosomal ROS production is dependent on extracellular Ca(2+) entry. We demonstrate that the observed Ca(2+) influx is supported by ORAI calcium release-activated calcium modulator 1 (Orai1) and stromal interaction molecule 1 (STIM1). This result suggests that extracellular Ca(2+) entry, which is required for ROS production, is mediated by a store-operated Ca(2+) mechanism. Finally, our data identify the complex formed by S100A8 and S100A9 (S100 calcium-binding protein A8 and A9 complex), two Ca(2+)-binding proteins, as the site of interplay between extracellular Ca(2+) entry and intraphagosomal ROS production. Thus, we demonstrate that FcγR-mediated phagocytosis requires intracellular Ca(2+) store depletion for the internalization phase. Then phagosomal ROS production requires extracellular Ca(2+) entry mediated by Orai1/STIM1 and relayed by S100A8-A9 as Ca(2+) sensor.     

Selection of large quantities of embryogenic calli from indica rice seeds for production of fertile transgenic plants using the biolistic method

The microprojectile bombardment of immature embryos has proven to be effective in transforming many indica rice varieties. One of the drawbacks of using immature embryos is the requirement of a large number of high quality immature embryos, which itself is a tedious and laborious process. To circumvent these problems, we have developed a procedure, using indica variety TN1 as a model that generates highly homogenous populations of embryogenic subcultured calli by selectively propagating a small number of regeneration-proficient calli derived from seeds. Thousands of embryogenic calli were produced from 50 seeds within 10 weeks. Ten to 20 independent R0 transgenic lines were regenerated per 500 embryogenic calli bombarded. The convenience and reliability offered by this transformation system has made transformation of indica rice a routine procedure.Abbreviations 2,4-D 2,4-dichlorophenoxy acetic acid - NAA naphthalene acetic acid - BAP 6-benzylaminopurine - kb kilobase - GUS -glucuronidase - X-gluc 5-bromo-4-chloro-3-indolyl--D-glucuronide - HPH hygromycin B phosphotransferase     

Importance of N2-Fixation on the Productivity at the North-Western Azores Current/Front System,and the Abundance of Diazotrophic Unicellular Cyanobacteria

To understand the impact of the northwestern Azores Current Front (NW-AzC/AzF) system on HCO₃⁻-and N₂-fixation activities and unicellular diazotrophic cyanobacteria (UCYN) distribution, we combined geochemical and biological approaches from the oligotrophic surface to upper mesopelagic waters. N₂-fixation was observed to sustain 45–85% of the HCO₃⁻-fixation in the picoplanktonic fraction performing 47% of the total C-fixation at the deep chlorophyll maximum north and south of the AzF. N₂-fixation rates as high as 10.9 μmol N m^-3 d^-1 and surface nitrate δ¹⁵N as low as 2.7‰ were found in the warm (18–24°C), most saline (36.5–37.0) and least productive waters south of the AzF, where UCYN were the least abundant. However, picoplanktonic UCYN abundances up to 55 cells mL^-1 were found at 45–200m depths in the coolest nutrient-rich waters north of the AzF. In this area, N₂-fixation rates up to 4.5 μmol N m^-3 d^-1 were detected, associated with depth-integrated H¹³CO₃⁻-fixation rates at least 50% higher than observed south of the AzF. The numerous eddies generated at the NW-AzC/AzF seem to enhance exchanges of plankton between water masses, as well as vertical and horizontal diapycnal diffusion of nutrients, whose increase probably enhances the growth of diazotrophs and the productivity of C-fixers.     

Combination of Insecticide Treated Nets and Indoor Residual Spraying in Northern Tanzania Provides Additional Reduction in Vector Population Density and Malaria Transmission Rates Compared to Insecticide Treated Nets Alone: A Randomised Control Trial

Indoor residual spraying (IRS) combined with insecticide treated nets (ITN) has been implemented together in several sub-Saharan countries with inconclusive evidence that the combined intervention provides added benefit. The impact on malaria transmission was evaluated in a cluster randomised trial comparing two rounds of IRS with bendiocarb plus universal coverage ITNs, with ITNs alone in northern Tanzania. From April 2011 to December 2012, eight houses in 20 clusters per study arm were sampled monthly for one night with CDC light trap collections. Anopheles gambiae s.l. were identified to species using real time PCR Taq Man and tested for the presence of Plasmodium falciparum circumsporozoite protein. ITN and IRS coverage was estimated from household surveys. IRS coverage was more than 85% in two rounds of spraying in January and April 2012. Household coverage with at least one ITN per house was 94.7% after the universal coverage net campaign in the baseline year and the proportion of household with all sleeping places covered by LLIN was 50.1% decreasing to 39.1% by the end of the intervention year. An.gambiae s.s. comprised 80% and An.arabiensis 18.3% of the anopheline collection in the baseline year. Mean An.gambiae s.l. density in the ITN+IRS arm was reduced by 84% (95%CI: 56%-94%, p = 0.001) relative to the ITN arm. In the stratum of clusters categorised as high anopheline density at baseline EIR was lower in the ITN+IRS arm compared to the ITN arm (0.5 versus 5.4 per house per month, Incidence Rate Ratio: 0.10, 95%CI: 0.01–0.66, p-value for interaction <0.001). This trial provides conclusive evidence that combining carbamate IRS and ITNs produces major reduction in Anopheles density and entomological inoculation rate compared to ITN alone in an area of moderate coverage of LLIN and high pyrethroid resistance in An.gambiae s.s.