Assessment of Benthic Flux of Dissolved Organic Carbon in Estuaries Using the Eddy Correlation Technique

Dissolved organic carbon (DOC) is a water quality concern in estuarine environments, as DOC facilitates mobilization of metals and organics in sediments and leads to toxic disinfection byproducts during water treatment. Export of DOC from sediments can vary with changing environmental conditions, including wetland restoration and rising sea levels. Therefore, it is important to quantify flux of DOC across the sediment-water interface (SWI). Existing DOC flux measurement techniques, such as equilibrium dialysis, porewater extraction, and benthic chamber measurement, are intrusive to the sediment environment and underestimate flux by only capturing certain flux contributions. In this research, methods for estimating benthic DOC flux using the eddy correlation technique (also known as the eddy covariance technique) were developed and implemented at three estuarine mudflats and one freshwater wetland throughout Maine and New Hampshire. The eddy correlation technique, first developed for use in atmospheric sciences and later applied to aquatic O2 and groundwater flux measurement, is a non-intrusive, in situ method based on measurement of turbulent fluctuations of properties such as fluid velocity, solute concentration, and temperature. The methods employed here utilized vertical velocity vectors obtained with an acoustic Doppler velocimeter (ADV) and DOC concentrations approximated with a chromophoric dissolved organic matter (CDOM) fluorometer. Both linear regression and moving average techniques were investigated for isolation of turbulent fluctuations in the velocity and concentration data, and spectral analysis was used to analyze flux contribution in the frequency series. DOC flux values obtained using eddy correlation were compared with results from porewater extraction. Eddy flux values were typically an order of magnitude higher than the diffusive fluxes calculated from porewater gradients, which are thought to underestimate flux, as turbulent eddy diffusion dominates vertical transport in these aquatic systems. Reasonable flux estimates are a function of adequate trend removal to separate turbulent fluctuations from mean flows and wave-induced fluctuations. This can be difficult in heterogeneous environments such as the ones studied here. In addition, spectral analysis shows that DOC flux estimates can be compromised by high-frequency noise caused by particle attenuation of the CDOM fluorometer measurements

Bone Marrow Stromal Cells Modulate Mouse ENT1 Activity and Protect Leukemia Cells from Cytarabine Induced Apoptosis

BACKGROUND: Despite a high response rate to chemotherapy, the majority of patients with acute myeloid leukemia (AML) are destined to relapse due to residual disease in the bone marrow (BM). The tumor microenvironment is increasingly being recognized as a critical factor in mediating cancer cell survival and drug resistance. In this study, we propose to identify mechanisms involved in the chemoprotection conferred by the BM stroma to leukemia cells. METHODS: Using a leukemia mouse model and a human leukemia cell line, we studied the interaction of leukemia cells with the BM microenvironment. We evaluated in vivo and in vitro leukemia cell chemoprotection to different cytotoxic agents mediated by the BM stroma. Leukemia cell apoptosis was assessed by flow cytometry and western blotting. The activity of the equilibrative nucleoside transporter 1 (ENT1), responsible for cytarabine cell incorporation, was investigated by measuring transport and intracellular accumulation of (3)H-adenosine. RESULTS: Leukemia cell mobilization from the bone marrow into peripheral blood in vivo using a CXCR4 inhibitor induced chemo-sensitization of leukemia cells to cytarabine, which translated into a prolonged survival advantage in our mouse leukemia model. In vitro, the BM stromal cells secreted a soluble factor that mediated significant chemoprotection to leukemia cells from cytarabine induced apoptosis. Furthermore, the BM stromal cell supernatant induced a 50% reduction of the ENT1 activity in leukemia cells, reducing the incorporation of cytarabine. No protection was observed when radiation or other cytotoxic agents such as etoposide, cisplatin and 5-fluorouracil were used. CONCLUSION: The BM stroma secretes a soluble factor that significantly protects leukemia cells from cytarabine-induced apoptosis and blocks ENT1 activity. Strategies that modify the chemo-protective effects mediated by the BM microenvironment may enhance the benefit of conventional chemotherapy for patients with AML

Phylogenomic analysis of a 55.1 kb 19-gene dataset resolves a monophyletic Fusarium that includes the Fusarium solani Species Complex

Scientific communication is facilitated by a data-driven, scientifically sound taxonomy that considers the end-user¿s needs and established successful practice. In 2013, the Fusarium community voiced near unanimous support for a concept of Fusarium that represented a clade comprising all agriculturally and clinically important Fusarium species, including the F. solani species complex (FSSC). Subsequently, this concept was challenged in 2015 by one research group who proposed dividing the genus Fusarium into seven genera, including the FSSC described as members of the genus Neocosmospora, with subsequent justification in 2018 based on claims that the 2013 concept of Fusarium is polyphyletic. Here, we test this claim and provide a phylogeny based on exonic nucleotide sequences of 19 orthologous protein-coding genes that strongly support the monophyly of Fusarium including the FSSC. We reassert the practical and scientific argument in support of a genus Fusarium that includes the FSSC and several other basal lineages, consistent with the longstanding use of this name among plant pathologists, medical mycologists, quarantine officials, regulatory agencies, students, and researchers with a stake in its taxonomy. In recognition of this monophyly, 40 species described as genus Neocosmospora were recombined in genus Fusarium, and nine others were renamed Fusarium. Here the global Fusarium community voices strong support for the inclusion of the FSSC in Fusarium, as it remains the best scientific, nomenclatural, and practical taxonomic option availabl

Design and Control of a 3-D crane

The goal of this project is to design and construct a 3-D crane for use in a classroom setting for a better understanding of dynamics, vibrations and controls concepts, and develop a manual for its use. The developed control system demonstrates the advantages of closed versus open loop controllers. Using MATLAB®’s Simulink, a control software package, along with a dSPACE ACE 1103 interface board that communicates with the electronic components of the crane, a working educational tool is realized

Primary mouse and human BMSCs supernatant protect leukemia cells from Ara-C induced cytotoxicity.

<p>APL and U-937cells were cultured with or without primary mouse BM stromal cell supernatant (PM-BM SN) or human BM SN (HS5-BM SN) for 2 hours before treatment with Ara-C (0, 250 and 500 ng/ml) (A) or Ara-C (0, 300 and 600 ng/ml) (B) for 24 hours. Leukemia cell viability was assessed by the MTT assay. Each bar represents the mean ± SD of 3 independent experiments. ***<i>p</i><0.001 (leukemia cells versus leukemia cells + mouse or human BM SN).</p

BMSCs secrete a soluble factor(s) that protects APL cells from Ara-C induced apoptosis.

<p>(A) Adherence assay: APL cells were cultured alone, co-cultured with M2-BMSCs or with fibronectin-coated plates for 24 hours. Cells were processed and quantification of APL GR1+ cells in the supernatant and adhered fractions were performed by flow cytometry analysis. Adherence was calculated as the percentage of APL cells present in the adhered fraction in relation to the total amount of APL cells in both fractions. For chemosensitivity studies: (B) APL cells were cultured alone, cultured using fibronectin pre-coated wells, or cultured with M2-BMSCs for 4 hours; (C) APL were cultured with or without M2-BMSCs or using a transwell system. Cultures were incubated for 2 hours before treatment with Ara-C (125, 250, 500 ng/ml) for 24 hours or vehicle alone (control). APL cell death was assessed by flow cytometry using the GR-1-APC mouse antibody and the annexin V-PE apoptosis kit. Each bar represents the mean ± SEM of 3 independent experiments. **p<0.01 and ***p<0.001 (all groups versus APL).</p

BMSC soluble factor(s) inhibits mENT1 activity and protect APL cells from AraC-induced apoptosis.

<p>(A) Measurement of mENT1 activity. APL cells were cultured alone or with M2-BM SN for 24 hours. Cells were harvested and mENT1 activity was measured by the incorporation of radioactive ³H-adenosine (B) RNA extraction from APL cells cultured alone or in presence of M2-BM SN for a time-course of 0, 3, 6, 9, 15, and 24 hours was used for RT-PCR to detect expression of mENT1. (C) Western blot analysis for mENT1 using APL cells with or without M2-BM SN for 24 hours. Each bar represents the mean ± SD of 3 independent experiments. ***<i>p</i><0.001 (APL versus APL SN).</p

BMSCs supernatant caused no APL cell cycle arrest.

<p>APL cells were cultured with or without M2-BM SN for 24 hours. Cells were harvested, fixed and stained with PI and analyzed by flow cytometry. Upper panels show representative histograms of APL cells in the absence (left upper panel) and presence of M2-BM SN (right upper panel). Lower figure shows mean and SD of three separate experiments.</p