08/05/2021
Harmful cyanobacterial blooms pose an environmental health hazard due to the release of water-soluble cyanotoxins. One of the most prevalent cyanotoxins in nature is microcystins (MCs), a class of cyclic heptapeptide hepatotoxins, and they are produced by several common cyanobacteria in aquatic environments. Once released from cyanobacterial cells, MCs are subjected to physical chemical and biological transformations in natural environments. MCs can also be taken up and accumulated in aquatic organisms and their grazers/predators and induce toxic effects in several organisms, including humans. This brief review aimed to summarize our current understanding on the chemical structure, exposure pathway, cytotoxicity, biosynthesis, and environmental transformation of microcystins.
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09/03/2020
According to the UNICEF, children between 0–14 years represent ~26% of the total global population (~45% in Africa; 22% in USA, of which 90% attend school; ranging from 85–100% across countries). With high case-fatality ratios between 4.5–7.5% (Germany/Iran/USA/Brazil/Canada) and 11.9–16.4% (Spain/Italy/UK/France/Belgium), there is a critical need to empower citizens, especially children (often asymptomatic carriers), with education strategies to control COVID-19. Especially, there is need to support facemask citizen science and experiential education among children and families as the globe exits from the current lockdown, and teachers and students desire and seek for safe strategies to return to densely-attended schools. COVID-19 is a pandemic respiratory disease that disseminates as infectious respiratory or saliva droplets are released into the environment as people talk, sneeze, and cough. Currently the most publicized methods to prevent local transmission of COVID-19 and promote “droplet safety” in hospitals and communities include hand washing, social distancing, and stay-at-home strategies. In contrast to established benefits for medical masks in hospitals, the benefits of wearing masks or face covers/coverings (hereafter, “facemask”) in the community have been inconsistently debated by the media, creating confusion, and misinformation. Furthermore, high-profile political leaders in countries heavily affected by the pandemic have given misleading signs regarding containment measures associated with COVID-19 increasingly polarizing local communities around arguments on the value of facemasks in promoting public health, which is critically important to incentivize during the emergence of citizens from their lockdowns and during the phase of reopening local economies.
First publication and copyright by Frontiers Media.
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01/01/1997
Viral and bacterial abundances were determined in various habitats (water, sediments, soil, leaves) within a northeastern Ohio catchment. Viral densities ranged from 1.98 to 2.02 x 10(7)/mL in water and from 1.65 to 6.68 x 10(8)/g AFDM in :particulate samples; their abundance was not correlated with bacterial abundance. Bacterial numbers were typical for similar lotic habitats with means of 1.63 x 10(6)/mL for water, 5.79 x 10(8) and 1.09 x 10(9)/g AFDM for sediments and leaves, respectively. The virus to bacterium ratio was highest in water and lowest on leaves.
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01/01/2005
Here we present a stochastic biogeochemical model for the formation, transformation and mineralization of natural organic matter (NOM). The model is agent-based, with each software agent representing a single molecule of defined composition. Molecular properties and reactivities are estimated from composition and environmental parameters. Environmental parameters including temperature, pH, light intensity, dissolved O2, moisture and enzyme activities are user controlled. Time is treated in discrete steps, and during each step potential reaction probabilities are evaluated for each molecule based on its structure and the environmental parameters. When reactions occur, the molecular composition is modified accordingly. The model uses small natural products and biopolymers for inputs, and the composition of the molecules produced is constrained only by the inputs and reaction stoichiometries, not by pre-defined structures. Example simulations using the program AlphaStep are presented, in which the breakdown of biopolymers and the condensation of small molecules both lead to molecular assemblages with elemental composition and average properties similar to those of aquatic NOM. This batch-reactor model can be expanded to include spatial information and environmental feedback.
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09/01/2004
There is increasing evidence that subcellular targeting of signaling molecules is an important means of regulating the protein kinase A (PKA) pathway. Subcellular organization of the signaling molecules in the PKA pathway insures that a signal initiated at the receptor level is transferred efficiently to a PKA substrate eliciting some cellular response. This subcellular targeting appears to regulate the function of a highly specialized cell such as the cardiac myocyte. This review focuses on A-kinase anchoring proteins (AKAPs) which are expressed in the heart. It has been determined that, of the approximately 13 different AKAPs expressed in cardiac tissue, several of these are expressed in cardiac myocytes. These AKAPs bind several PKA substrates and some appear to regulate PKA-dependent phosphorylation of these substrates. AKAP tethering of PKA may be essential for efficient regulation of cardiac muscle contraction. The ability of an AKAP to anchor PKA may be altered in the failing heart, thus compromising the ability of the myocyte to respond to stimuli which elicit the PKA pathway.
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04/01/1999
Abundance of virus-like particles (VLP) was determined in Lake Erie subsurface water.The relationship between VLP and the bacterial and phytoplankton communities were investigated. Viral and bacterial numbers were determined using nucleic acid stains and epifluorescent microscopy. Phytoplankton abundance was estimated by chlorophylls extraction. Viral abundance averaged 1.05 x 106 VLP/ml and the ratio of viral to bacterial number was less than 1.0 across most sampling sites and dates. Viral abundance was not correlated with either bacterial abundance or chlorophyll a concentration. Viral abundance was found to be most similar to other Great Lakes and marine systems and dissimilar to other freshwater systems.
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01/01/2005
The population sizes of three bacterial species, Acinetobacter calcoaceticus, Burkholderia cepacia, and Pseudomonas putida, were examined in water and sediment from nine streams in different parts of the United States using fluorescent in situ hybridization (FISH). Population sizes were determined from three sites (upstream, midstream, and downstream) in each stream to compare differences in the occurrence and distribution of the species within each stream and among streams. Physical and chemical variables measured reflected differences in environmental conditions among the streams. In the water, B. cepacia numbers were highest in the agricultural, Iowa stream. P. putida numbers were highest in the southern coastal plain streams, Black Creek (GA) and Meyers Branch (SC). Compared to the other two species, the abundance of A. calcoaceticus was similar in all the streams. In sediment, the greatest abundance of all three species was found in the Iowa stream, while the lowest was in Hugh White Creek (NC). Detrended correspondence analysis (DCA) explained 95.8% and 83.9% of the total variation in bacterial numbers in water and sedment of the streams, respectively. In sediments and water, B. cepacia numbers were related to nitrate concentrations. A. calcoaceticus in water clustered with several environmental variables (i.e., SRP, pH, and conductivity) but benthic populations were less well correlated with these variables. This study reveals the potential influence of various environmental conditions on different bacterial populations in stream communities.
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10/25/2021
Adenosine Deaminases that Act on RNA (ADARs) are RNA editing enzymes that play a dynamic and nuanced role in regulating transcriptome and proteome diversity. This editing can be highly selective, affecting a specific site within a transcript, or nonselective, resulting in hyperediting. ADAR editing is important for regulating neural functions and autoimmunity, and has a key role in the innate immune response to viral infections, where editing can have a range of pro- or antiviral effects and can contribute to viral evolution. Here we examine the role of ADAR editing across a broad range of viral groups. We propose that the effect of ADAR editing on viral replication, whether pro- or antiviral, is better viewed as an axis rather than a binary, and that the specific position of a given virus on this axis is highly dependent on virus- and host-specific factors, and can change over the course of infection. However, more research needs to be devoted to understanding these dynamic factors and how they affect virus–ADAR interactions and viral evolution. Another area that warrants significant attention is the effect of virus–ADAR interactions on host–ADAR interactions, particularly in light of the crucial role of ADAR in regulating neural functions. Answering these questions will be essential to developing our understanding of the relationship between ADAR editing and viral infection. In turn, this will further our understanding of the effects of viruses such as SARS-CoV-2, as well as many others, and thereby influence our approach to treating these deadly diseases.
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01/01/2004
Algal-bacterial co-variation has been frequently observed in lentic and marine environments, but the existence of such relationships in lotic ecosystems is not well established. To examine possible co-variation, bacterial number and chlorophyll-a concentration in water and sediments of nine streams from different regions in the USA were examined. In the water, a strong relationship was found between chlorophyll concentration and bacterial abundance. There was not a significant linear relationship between the abundance of sediment bacteria and sediment or water chlorophyll concentration. The linear regression results obtained between bacterial numbers and chlorophyll concentration in water were generally similar to those reported in other studies on lentic and marine systems suggesting that factors that cause this co-variation may be similar.
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04/13/2007
Phosphatidic acid (PA) is a minor but important phospholipid that, through specific interactions with proteins, plays a central role in several key cellular processes. The simple yet unique structure of PA, carrying just a phosphomonoester head group, suggests an important role for interactions with the positively charged essential residues in these proteins. We analyzed by solid-state magic angle spinning 31P NMR and molecular dynamics simulations the interaction of low concentrations of PA in model membranes with positively charged side chains of membrane-interacting peptides. Surprisingly, lysine and arginine residues increase the charge of PA, predominantly by forming hydrogen bonds with the phosphate of PA, thereby stabilizing the protein-lipid interaction. Our results demonstrate that this electrostatic/hydrogen bond switch turns the phosphate of PA into an effective and preferred docking site for lysine and arginine residues. In combination with the special packing properties of PA, PA may well be nature's preferred membrane lipid for interfacial insertion of positively charged membrane protein domains.
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