Import, export, and recycling of dissolved nutrients in the Ogeechee River estuary (Georgia, USA)

We constructed an empirical mass balance model of nutrient fluxes in the Ogeechee River estuary (Georgia, USA) from eight surveys of seasonal estuarine nutrient concentrations during 2015 and 2016. The model results indicated a net removal of dissolved phosphorus and a net production of dissolved nitrogen (N) within the estuary over an annual cycle. During summer and autumn low flow periods, much of the dissolved N discharged to the ocean seems to be recycled into the estuary in the form of phytoplankton biomass. As a result, the outwelled N is not new nitrogen fueling coastal production but is nitrogen trapped within a recycling loop across the ocean–estuarine boundary. Higher flows in the fall and winter lead to direct discharge of nutrients with minimal recycling. A balanced N budget for the Ogeechee River estuary requires that estuarine N-fixation must exceed burial and denitrification losses within the estuary

Exosomes Mediate Zika Virus Transmission Through SMPD3 Neutral Sphingomyelinase in Cortical Neurons

The harmful effects of ZIKA virus (ZIKV) infection are reflected by severe neurological manifestations such as microcephaly in neonates and other complications associated with Guillain-Barre syndrome in adults. The transmission dynamics of ZIKV in or between neurons, or within the developing brains of the foetuses are not fully understood. Using primary cultures of murine cortical neurons, we show that ZIKV uses exosomes as mediators of viral transmission between neurons. Cryo-electron microscopy showed heterogeneous population of neuronal exosomes with a size range of 30-200 nm. Increased production of exosomes from neuronal cells was noted upon ZIKV infection. Neuronal exosomes contained both ZIKV viral RNA and protein(s) that were highly infectious to naive cells. RNaseA and neutralizing antibodies treatment studies suggest the presence of viral RNA/proteins inside exosomes. Exosomes derived from time- and dose-dependent incubations showed increasing viral loads suggesting higher packaging and delivery of ZIKV RNA and proteins. Furthermore, we noted that ZIKV induced both activity and gene expression of neutral Sphingomyelinase (nSMase)-2/SMPD3, an important molecule that regulates production and release of exosomes. Silencing of SMPD3 in neurons resulted in reduced viral burden and transmission through exosomes. Treatment with SMPD3 specific inhibitor GW4869, significantly reduced ZIKV loads in both cortical neurons and in exosomes derived from these neuronal cells. Taken together, our results suggest that ZIKV modulates SMPD3 activity in cortical neurons for its infection and transmission through exosomes perhaps leading to severe neuronal death that may result in neurological manifestations such as microcephaly in the developing embryonic brains

The impact of obstructive sleep apnea variability measured in-lab versus in-home on sample size calculations

<p>Abstract</p> <p>Background</p> <p>When conducting a treatment intervention, it is assumed that variability associated with measurement of the disease can be controlled sufficiently to reasonably assess the outcome. In this study we investigate the variability of Apnea-Hypopnea Index obtained by polysomnography and by in-home portable recording in untreated mild to moderate obstructive sleep apnea (OSA) patients at a four- to six-month interval.</p> <p>Methods</p> <p>Thirty-seven adult patients serving as placebo controls underwent a baseline polysomnography and in-home sleep study followed by a second set of studies under the same conditions. The polysomnography studies were acquired and scored at three independent American Academy of Sleep Medicine accredited sleep laboratories. The in-home studies were acquired by the patient and scored using validated auto-scoring algorithms. The initial in-home study was conducted on average two months prior to the first polysomnography, the follow-up polysomnography and in-home studies were conducted approximately five to six months after the initial polysomnography.</p> <p>Results</p> <p>When comparing the test-retest Apnea-hypopnea Index (AHI) and apnea index (AI), the in-home results were more highly correlated (r = 0.65 and 0.68) than the comparable PSG results (r = 0.56 and 0.58). The in-home results provided approximately 50% less test-retest variability than the comparable polysomnography AHI and AI values. Both the overall polysomnography AHI and AI showed a substantial bias toward increased severity upon retest (8 and 6 events/hr respectively) while the in-home bias was essentially zero. The in-home percentage of time supine showed a better correlation compared to polysomnography (r = 0.72 vs. 0.43). Patients biased toward more time supine during the initial polysomnography; no trends in time supine for in-home studies were noted.</p> <p>Conclusion</p> <p>Night-to-night variability in sleep-disordered breathing can be a confounding factor in assessing treatment outcomes. The sample size of this study was small given the night-to-night variability in OSA and limited understanding of polysomnography reliability. We found that in-home studies provided a repeated measure of sleep disordered breathing less variable then polysomnography. Investigators using polysomnography to assess treatment outcomes should factor in the increased variability and bias toward increased AHI values upon retest to ensure the study is adequately powered.</p

Nearshore internal bores and turbulent mixing in southern Monterey Bay

We observed transient stratification and mixing events associated with nearshore internal bores in southern Monterey Bay using an array of instruments with high spatial and temporal resolution. The arrival of the bores is characterized by surging masses of dense (cold) water that tend to stratify the water column. The bore is followed by a gradual drop in the temperature throughout the water column over several hours (defined here as the bore period) until a sharp warm-front relaxation, followed by high frequency temperature fluctuations, returns the column back to nearly its original state (defined here as the mixing period). Mixing periods revealed increased temperature variance at high frequencies (ω \u3e ), as well as a greater percentage of events where dynamic instabilities may be present (Ri\u3c 0.25), suggesting active mixing of the stratified water column. Turbulent dissipation rates in the stratified interior during the mixing period, estimated using the technique of isopycnal slope spectra, revealed mean values the same order of magnitude as near-bed bottom-generated turbulence. Observations indicate that local shear-produced turbulent kinetic energy by the warm front relaxations dominates mixing in the stratified interior. The non-canonical nature of these bore and relaxation events is also investigated with a numerical model, and the dynamics are shown to depend on the internal Iribarren number. Our results suggest that nearshore internal bores interacting with local bathymetry dramatically alter local dynamics and mixing in the nearshore with important ecological implications

Discovery of Exosomes From Tick Saliva and Salivary Glands Reveals Therapeutic Roles for CXCL12 and IL-8 in Wound Healing at the Tick-Human Skin Interface

Ticks secrete various anti-coagulatory, anti-vasoconstrictory, anti-inflammatory, and anti-platelet aggregation factors in their saliva at the bite site during feeding to evade host immunological surveillance and responses. For the first time, we report successful isolation of exosomes (small membrane-bound extracellular signaling vesicles) from saliva and salivary glands of partially fed or unfed ixodid ticks. Our data showed a novel role of these in vivo exosomes in the inhibition of wound healing via downregulation of C-X-C motif chemokine ligand 12 (CXCL12) and upregulation of interleukin-8 (IL-8). Cryo-electron microscopy (cryo-EM) analysis revealed that tick saliva and salivary glands are composed of heterogeneous populations of in vivo exosomes with sizes ranging from 30 to 200 nm. Enriched amounts of tick CD63 ortholog protein and heat shock protein 70 (HSP70) were evident in these exosomes. Treatment of human skin keratinocytes (HaCaT cells) with exosomes derived from tick saliva/salivary glands or ISE6 cells dramatically delayed cell migration, wound healing, and repair process. Wound healing is a highly dynamic process with several individualized processes including secretion of cytokines. Cytokine array profiling followed by immunoblotting and quantitative-PCR analysis revealed that HaCaT cells treated with exosomes derived from tick saliva/salivary glands or ISE6 cells showed enhanced IL-8 levels and reduced CXCL12 loads. Inhibition of IL-8 or CXCL12 further delayed exosome-mediated cell migration, wound healing, and repair process, suggesting a skin barrier protection role for these chemokines at the tick bite site. In contrast, exogenous treatment of CXCL12 protein completely restored this delay and enhanced the repair process. Taken together, our study provides novel insights on how tick salivary exosomes secreted in saliva can delay wound healing at the bite site to facilitate successful blood feeding

Northern Monterey Bay upwelling shadow front : observations of a coastally and surface-trapped buoyant plume

Author Posting. © American Geophysical Union, 2009. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research 114 (2009): C12013, doi:10.1029/2009JC005623.During the upwelling season in central California, northwesterly winds along the coast produce a strong upwelling jet that originates at Point Año Nuevo and flows southward across the mouth of Monterey Bay. A convergent front with a mean temperature change of 3.77 ± 0.29°C develops between the warm interior waters and the cold offshore upwelling jet. To examine the forcing mechanisms driving the location and movement of the upwelling shadow front and its effects on biological communities in northern Monterey Bay, oceanographic conditions were monitored using cross-shelf mooring arrays, drifters, and hydrographic surveys along a 20 km stretch of coast extending northwestward from Santa Cruz, California, during the upwelling season of 2007 (May–September). The alongshore location of the upwelling shadow front at the northern edge of the bay was driven by: regional wind forcing, through an alongshore pressure gradient; buoyancy forces due to the temperature change across the front; and local wind forcing (the diurnal sea breeze). The upwelling shadow front behaved as a surface-trapped buoyant current, which is superimposed on a poleward barotropic current, moving up and down the coast up to several kilometers each day. We surmise that the front is advected poleward by a preexisting northward barotropic current of 0.10 m s−1 that arises due to an alongshore pressure gradient caused by focused upwelling at Point Año Nuevo. The frontal circulation (onshore surface currents) breaks the typical two-dimensional wind-driven, cross-shelf circulation (offshore surface currents) and introduces another way for water, and the material it contains (e.g., pollutants, larvae), to go across the shelf toward shore.Funded primarily by the Gordon and Betty Moore Foundation and the David and Lucile Packard Foundation

Arthropod EVs Mediate Dengue Virus Transmission Through Interaction With a Tetraspanin Domain Containing Glycoprotein Tsp29Fb

Dengue virus (DENV) is a mosquito-borne flavivirus that causes dengue fever in humans, worldwide. Using in vitro cell lines derived from Aedes albopictus and Aedes aegypti, the primary vectors of DENV, we report that DENV2/DENV3-infected cells secrete extracellular vesicles (EVs), including exosomes, containing infectious viral RNA and proteins. A full-length DENV2 genome, detected in arthropod EVs, was infectious to naïve mosquito and mammalian cells, including human-skin keratinocytes and blood endothelial cells. Cryo-electron microscopy showed mosquito EVs with a size range from 30 to 250 nm. Treatments with RNase A, Triton X-100, and 4G2 antibody-bead binding assays showed that infectious DENV2-RNA and proteins are contained inside EVs. Viral plaque formation and dilution assays also showed securely contained infectious viral RNA and proteins in EVs are transmitted to human cells. Up-regulated HSP70 upon DENV2 infection showed no role in viral replication and transmission through EVs. In addition, qRT-PCR and immunoblotting results revealed that DENV2 up-regulates expression of a mosquito tetraspanin-domain–containing glycoprotein, designated as Tsp29Fb, in A. aegypti mosquitoes, cells, and EVs. RNAi-mediated silencing and antibody blocking of Tsp29Fb resulted in reduced DENV2 loads in both mosquito cells and EVs. Immunoprecipitation showed Tsp29Fb to directly interact with DENV2 E-protein. Furthermore, treatment with GW4869 (exosome-release inhibitor) affected viral burden, direct interaction of Tsp29Fb with E-protein and EV-mediated transmission of viral RNA and proteins to naïve human cells. In summary, we report a very important finding on EV-mediated transmission of DENV2 from arthropod to mammalian cells through interactions with an arthropod EVs-enriched marker Tsp29Fb

Discovery of Exosomes From Tick Saliva and Salivary Glands Reveals Therapeutic Roles for CXCL12 and IL-8 in Wound Healing at the Tick–Human Skin Interface

© Copyright © 2020 Zhou, Tahir, Wang, Woodson, Sherman, Karim, Neelakanta and Sultana.Ticks secrete various anti-coagulatory, anti-vasoconstrictory, anti-inflammatory, and anti-platelet aggregation factors in their saliva at the bite site during feeding to evade host immunological surveillance and responses. For the first time, we report successful isolation of exosomes (small membrane-bound extracellular signaling vesicles) from saliva and salivary glands of partially fed or unfed ixodid ticks. Our data showed a novel role of these in vivo exosomes in the inhibition of wound healing via downregulation of C-X-C motif chemokine ligand 12 (CXCL12) and upregulation of interleukin-8 (IL-8). Cryo-electron microscopy (cryo-EM) analysis revealed that tick saliva and salivary glands are composed of heterogeneous populations of in vivo exosomes with sizes ranging from 30 to 200 nm. Enriched amounts of tick CD63 ortholog protein and heat shock protein 70 (HSP70) were evident in these exosomes. Treatment of human skin keratinocytes (HaCaT cells) with exosomes derived from tick saliva/salivary glands or ISE6 cells dramatically delayed cell migration, wound healing, and repair process. Wound healing is a highly dynamic process with several individualized processes including secretion of cytokines. Cytokine array profiling followed by immunoblotting and quantitative-PCR analysis revealed that HaCaT cells treated with exosomes derived from tick saliva/salivary glands or ISE6 cells showed enhanced IL-8 levels and reduced CXCL12 loads. Inhibition of IL-8 or CXCL12 further delayed exosome-mediated cell migration, wound healing, and repair process, suggesting a skin barrier protection role for these chemokines at the tick bite site. In contrast, exogenous treatment of CXCL12 protein completely restored this delay and enhanced the repair process. Taken together, our study provides novel insights on how tick salivary exosomes secreted in saliva can delay wound healing at the bite site to facilitate successful blood feeding