ALBERT

Description: Bacterial and yeast antagonists isolated from fruit surfaces have been effective in controlling various postharvest diseases and several microbial antagonists have been developed into commercial products. Our knowledge of the fruit microbial community with the exception of grapes, apples and some citrus fruit is rudimentary, and the potential of the resident yeasts for biocontrol remains largely unknown. We determined the occurrence of yeasts on plum surfaces during fruit development from the pre-hardening stage until harvest during two years. A total of 16 species from 13 genera were isolated. Species from three genera, basidiomycetes Rhodotorula (29.5%) and Sporidiobolus (24.7%) and the dimorphic ascomycete genus Aureobasidium (24.7%) constituted 78.7% of all isolations and were recovered throughout fruit development while Cryptococcus spp. constituted only 6.2% of the total plum isolates. The yeast community in the final sampling was significantly different from the first three samplings, reflecting a rapidly changing fruit habitat during the maturation of fruit. For example, Hanseniaspora , Pichia , Zygosaccharomyces , and Wickerhamomyces occurred only on the most mature fruit. Screening of the yeasts for antagonistic activity against Monilinia fructicola , a fungus that causes brown rot, revealed a range of biocontrol activities. Several isolates provided complete control of the decay on plums challenged with a pathogen suspension of 10 3 conidia/ mL, and more than 90% of control on fruit inoculated with the pathogen at a concentration 10 times higher. Some of the best antagonists included A . pullulans and R . phylloplana . Populations of both of these antagonists increased rapidly by several orders of magnitude in wounds of plums incubated at 24 ºC and 4 ºC. Our results indicate that plum surfaces harbor several yeast species with excellent potential for use in biological control of brown rot of stone fruits. This article is protected by copyright. All rights reserved.

Description: [1]  Several regions within California have significant air quality issues. Transport of pollutants emitted in one region to another region may add to the impact of local emissions. In this work, Lagrangian particle dispersion model simulations show the amounts of tracers that are transported within and among four regions, Southern California, the San Francisco Bay Area, the Central Valley, and the rest of the state. The simulations cover May and June of 2010, the CalNex experiment period. Tracers of automobile emissions and one type of agricultural emissions are used. Tracer mixing ratios are compared to airborne and ground-based measurements. The age of tracers in each location is also presented. Vertical profiles and diurnal cycles help to clarify the transport process. As is well known, Southern California emissions are transported to the east and affect the desert areas, and Bay Area automobile emissions are an important source of pollutants in the San Joaquin Valley. A novel result is that the Southern California Bight is filled with a mixture of well-aged carbon monoxide tracer from Southern California and the Bay Area. Air over the Bight is also affected by the agricultural emissions represented by the agricultural tracer, dominantly from the Central Valley where its sources are largest. There is no indication of transport from Southern California to the Central Valley. Emissions from the Central Valley do make their way to Southern California, as shown by the agricultural tracer, but automobile emissions from the Valley are insignificant in Southern California.

Description: [1]  The contemporary global carbon cycle is dominated by perturbations from anthropogenic CO 2 emissions. One approach to identify, quantify, and monitor anthropogenic emissions is to focus on intensely emitting urban areas. In this study, we compare the ability of different CO 2 observing systems to constrain anthropogenic flux estimates in the Los Angeles megacity. We consider different observing system configurations based on existing observations and realistic near-term extensions of the current ad hoc network. We use a high-resolution regional model (STILT-WRF) to simulate different observations and observational network designs within and downwind of the Los Angeles basin. A Bayesian inverse method is employed to quantify the relative ability of each network to improve constraints on flux estimates. Ground-based column CO 2 observations provide useful complementary information to surface observations due to lower sensitivity to localized dynamics, but column CO 2 observations from a single site do not appear to provide sensitivity to emissions from the entire LA megacity. Surface observations from remote, down-wind sites contain weak, sporadic urban signals and are complicated by other source/sink impacts, limiting their usefulness for quantifying urban fluxes in LA. We find a network of 8 optimally located in-city surface observation sites provides the minimum sampling required for accurate monitoring of CO 2 emissions in LA, and present a recommended baseline network design. We estimate that this network can distinguish fluxes on 8 week time-scales and 10 km spatial scales to within ~12 g C m -2 d -1 (~10% of average peak fossil CO 2 flux in the LA domain).

Description: [1]  Nitrous oxide (N 2 O) is an important gas for climate and for stratospheric chemistry, with a lifetime exceeding 100 years. Global concentrations have increased steadily since the 18 th century, apparently due to human-associated emissions, principally from the application of nitrogen fertilizers. However, quantitative studies of agricultural emissions at large spatial scales are lacking, inhibited by the difficulty of measuring small enhancements in atmospheric concentration. Here we derive regional emission rates for N 2 O in the agricultural heartland of California, based on analysis of in-situ airborne atmospheric observations collected using a new quantum cascade laser spectrometer. The data were obtained on board the NOAA WP-3 research aircraft during the CalNex (California Research at the Nexus of Air Quality and Climate Change) program in late spring, 2010. We coupled the WRF (Weather Research and Forecasting) model, a meso-scale meteorology model, with the STILT (Stochastic Time-Inverted Lagrangian Transport) model, a Lagrangian particle dispersion model, to link our in-situ airborne observations to surface emissions. We then used a variety of statistical methods to identify source areas and to optimize emission rates. Our results are consistent with the view that fertilizer application is the largest source of N 2 O in the Central Valley. The spatial distribution of surface emissions, based on California land use and activity maps, was very different than indicated in the leading emissions inventory (EDGAR 4.0). Our estimated total emission flux of N 2 O for California in May and June was 3–4 times larger than the annual mean given for the state by EDGAR and other inventories, indicating a strong seasonal variation. We estimated the statewide total annual emissions of N 2 O to be 0.042 ± 0.011 Tg N/yr, roughly equivalent to inventory values if we account for seasonal variations using observations obtained in the Midwestern United States. This state total N 2 O emission is 20.5 Tg CO 2 equivalent (100-year global warming potential (GWP) = 310 CO 2 eq/g N 2 O), accounting for approximately 4% of the state total greenhouse gas emissions.

Description: Chronic granulomatous disease (CGD) can result from any of four single gene defects involving the components of the superoxide (O−2 ) generating phagocyte nicotinamide adenine dinucleotide phosphate (NADPH) oxidase. We show that transduction of peripheral blood CD34+ hematopoietic progenitors from a p67phox deficient CGD patient with replication defective amphotropic retrovirus encoding p67phox (MFGS-p67phox) significantly corrected the CGD functional defect in phagocyte oxidase activity in vitro. Using a chemiluminescence assay of oxidase activity, we showed that transduced patient CD34+ progenitors differentiating to myeloid cells in culture produced 25% of the total superoxide produced by normal CD34+ progenitors differentiating in culture. A flow cytometric assay of oxidase activity used to assess the oxidase function of individual cells in the cultures indicated that up to 32% of maturing granulocytes derived from transduced CD34+ progenitors from the p67phox CGD patient were oxidase positive with the average level of correction per granulocyte of 85% of that seen with granulocytes in similar cultures of CD34+ progenitors from normal volunteers. Nitroblue tetrazolium dye reduction assays of colonies of transduced progenitors in soft agar indicated that in some studies restoration of oxidase activity occurred in myeloid cells within 44% of granulocyte-erythrocyte-monocyte colonies, and within 28% of the combined group of granulocyte colonies/monocyte colonies/granulocyte-monocyte colonies. These high correction rates were achieved without any selective regimen to enrich for transduced cells. This study provides a basis for development of gene therapy for the p67phox deficient form of CGD.

Description: Chronic granulomatous disease (CGD) can result from any of four single gene defects involving the components of the superoxide (O−2 ) generating phagocyte nicotinamide adenine dinucleotide phosphate (NADPH) oxidase. We show that transduction of peripheral blood CD34+ hematopoietic progenitors from a p67phox deficient CGD patient with replication defective amphotropic retrovirus encoding p67phox (MFGS-p67phox) significantly corrected the CGD functional defect in phagocyte oxidase activity in vitro. Using a chemiluminescence assay of oxidase activity, we showed that transduced patient CD34+ progenitors differentiating to myeloid cells in culture produced 25% of the total superoxide produced by normal CD34+ progenitors differentiating in culture. A flow cytometric assay of oxidase activity used to assess the oxidase function of individual cells in the cultures indicated that up to 32% of maturing granulocytes derived from transduced CD34+ progenitors from the p67phox CGD patient were oxidase positive with the average level of correction per granulocyte of 85% of that seen with granulocytes in similar cultures of CD34+ progenitors from normal volunteers. Nitroblue tetrazolium dye reduction assays of colonies of transduced progenitors in soft agar indicated that in some studies restoration of oxidase activity occurred in myeloid cells within 44% of granulocyte-erythrocyte-monocyte colonies, and within 28% of the combined group of granulocyte colonies/monocyte colonies/granulocyte-monocyte colonies. These high correction rates were achieved without any selective regimen to enrich for transduced cells. This study provides a basis for development of gene therapy for the p67phox deficient form of CGD.

Description: Natural killer (NK) cells have important functions in cancer immunosurveillance, BM allograft rejection, fighting infections, tissue homeostasis, and reproduction. NK cell–based therapies are promising treatments for blood cancers. Overcoming their currently limited efficacy requires a better understanding of the molecular mechanisms controlling NK cell development and dampening their effector functions. NK cells recognize the loss of self-antigens or up-regulation of stress-induced ligands on pathogen-infected or tumor cells through invariant NK cell receptors (NKRs), and then kill such stressed cells. Two second-messenger pathways downstream of NKRs are required for NK cell maturation and effector responses: PIP3 generation by PI3K and generation of diacylglycerol and IP3 by phospholipase-Cγ (PLCγ). In the present study, we identify a novel role for the phosphorylated IP3 metabolite inositol (1,3,4,5)tetrakisphosphate (IP4) in NK cells. IP4 promotes NK cell terminal differentiation and acquisition of a mature NKR repertoire. However, in mature NK cells, IP4 limits NKR-induced IFNγ secretion, granule exocytosis, and target-cell killing, in part by inhibiting the PIP3 effector-kinase Akt. This identifies IP4 as an important novel regulator of NK cell development and function and expands our understanding of the therapeutically important mechanisms dampening NK cell responses. Our results further suggest that PI3K regulation by soluble IP4 is a broadly important signaling paradigm.

Description: The differentiation of natural killer (NK) cells and a subpopulation of NK cells which requires an intact thymus, that is, thymic NK cells, is poorly understood. Previous in vitro studies indicate that double negative (CD4−CD8−, DN) thymocytes can develop into cells with NK cell markers, but these cells have not been well characterized. Herein, we generated and characterized NK cells differentiating from thymic DN precursors. Sorted DN1 (CD44+CD25−) CD122−NK1.1− thymocytes from Rag1−/− mice were adoptively transferred into Rag1−/−Ly5.1 congenic mice. After intrathymic injection, donor-derived cells phenotypically resembling thymic NK cells were found. To further study their differentiation, we seeded sorted DN1 CD122−NK1.1− thymocytes on irradiated OP9 bone marrow stromal cells with IL-15, IL-7, Flt3L, and stem cell factor. NK1.1+ cells emerged after 7 days. In vitro differentiated NK cells acquired markers associated with immature bone marrow–derived NK cells, but also expressed CD127, which is typically found on thymic NK cells. Furthermore, we found that in vitro cells generated from thymic precursors secreted cytokines when stimulated and degranulated on target exposure. Together, these data indicate that functional thymic NK cells can develop from a DN1 progenitor cell population.