Temporal dynamics in a red alga dominated geothermal feature in Yellowstone National Park.

Alga-dominated geothermal spring communities in Yellowstone National Park (YNP), USA, have been the focus of many studies, however, relatively little is known about the composition and community interactions which underpin these ecosystems. Our goal was to determine, in three neighboring yet distinct environments in Lemonade Creek, YNP, how cells cope with abiotic stressors over the diurnal cycle. All three environments are colonized by two photosynthetic lineages, and , both of which are extremophilic Cyanidiophyceae red algae.

"Antibacterial properties of nine indium(III) complexes of substituted pyrazoles/pyrazolate and the structural and solution characterization of the mer- and trans‑indium(III) complexes of 4-Me-pzH".

Two indium(III) complexes of formula mer-[InCl(4-Me-pzH)] and trans-[InCl(4-Me-pzH)]Cl·(4-Me-pzH)·(HO) were isolated from the same reaction mixture and crystallographically characterized. The two complexes exist in dynamic equilibrium and their dynamic behavior was probed by variable temperature H NMR spectroscopy in the 202 to 296 K range. Powder X-ray diffraction of the batch confirmed existence of both complexes in a 1:2 ratio.

Arsinothricin Inhibits Proliferation in Blood and Blocks Parasite Transmission to Mosquitoes.

Malaria, caused by protozoal parasites, remains a leading cause of morbidity and mortality. The parasite has a complex life cycle, with asexual and sexual forms in humans and mosquitoes. Most antimalarials target only the symptomatic asexual blood stage.

The ArsQ permease and transport of the antibiotic arsinothricin.

The pentavalent organoarsenical arsinothricin (AST) is a natural product synthesized by the rhizosphere bacterium Burkholderia gladioli GSRB05. AST is a broad-spectrum antibiotic effective against human pathogens such as carbapenem-resistant Enterobacter cloacae. It is a non-proteogenic amino acid and glutamate mimetic that inhibits bacterial glutamine synthetase.

Arsenic and Mercury Distribution in an Aquatic Food Chain: Importance of Femtoplankton and Picoplankton Filtration Fractions.

Arsenic (As) and mercury (Hg) were examined in the Yellowstone Lake food chain, focusing on two lake locations separated by approximately 20 km and differing in lake floor hydrothermal vent activity. Sampling spanned from femtoplankton to the main fish species, Yellowstone cutthroat trout and the apex predator lake trout. Mercury bioaccumulated in muscle and liver of both trout species, biomagnifying with age, whereas As decreased in older fish, which indicates differential exposure routes for these metal(loid)s.

Arsenic Metabolism, Toxicity and Accumulation in the White Button Mushroom .

Mushrooms have unique properties in arsenic metabolism. In many commercial and wild-grown mushrooms, arsenobetaine (AsB), a non-toxic arsenical, was found as the dominant arsenic species. The AsB biosynthesis remains unknown, so we designed experiments to study conditions for AsB formation in the white button mushroom, .

Selective Methylation by an ArsM -Adenosylmethionine Methyltransferase from GSRB05 Enhances Antibiotic Production.

Arsenic methylation contributes to the formation and diversity of environmental organoarsenicals, an important process in the arsenic biogeochemical cycle. The gene encoding an arsenite (As(III)) -adenosylmethionine (SAM) methyltransferase is widely distributed in members of every kingdom. A number of ArsM enzymes have been shown to have different patterns of methylation.

Chemical synthesis of the organoarsenical antibiotic arsinothricin.

We report two routes of chemical synthesis of arsinothricin (AST), the novel organoarsenical antibiotic. One is by condensation of the 2-chloroethyl(methyl)arsinic acid with acetamidomalonate, and the second involves reduction of the -acetyl protected derivative of hydroxyarsinothricin (AST-OH) and subsequent methylation of a trivalent arsenic intermediate with methyl iodide. The enzyme AST -acetyltransferase (ArsN1) was utilized to purify l-AST from racemic AST.

The ArsI C-As lyase: Elucidating the catalytic mechanism of degradation of organoarsenicals.

Organoarsenicals such as monosodium methylarsenate (MSMA or MAs(V)) and roxarsone (4-hydroxyl-3-nitrophenylarsenate or Rox(V)) have been extensively used as herbicides and growth enhancers for poultry, respectively. Degradation of organoarsenicals to inorganic arsenite (As(III)) contaminates crops and drinking water. One such process is catalyzed by the bacterial enzyme ArsI, whose gene is found in many soil bacteria.

An ArsRC fusion protein enhances arsenate sensing and detoxification.

Arsenical resistance (ars) operons encode genes for arsenic resistance and biotransformation. The majority are composed of individual genes, but fusion of ars genes is not uncommon, although it is not clear if the fused gene products are functional. Here we report identification of a four-gene ars operon from Paracoccus sp.

Arsenic in medicine: past, present and future.

Arsenicals are one of the oldest treatments for a variety of human disorders. Although infamous for its toxicity, arsenic is paradoxically a therapeutic agent that has been used since ancient times for the treatment of multiple diseases. The use of most arsenic-based drugs was abandoned with the discovery of antibiotics in the 1940s, but a few remained in use such as those for the treatment of trypanosomiasis.

Identification of the Biosynthetic Gene Cluster for the Organoarsenical Antibiotic Arsinothricin.

The soil bacterium Burkholderia gladioli GSRB05 produces the natural compound arsinothricin [2-amino-4-(hydroxymethylarsinoyl) butanoate] (AST), which has been demonstrated to be a broad-spectrum antibiotic. To identify the genes responsible for AST biosynthesis, a draft genome sequence of GSRB05 was constructed. Three genes, , in an arsenic resistance operon were found to be a biosynthetic gene cluster responsible for synthesis of AST and its precursor, hydroxyarsinothricin [2-amino-4-(dihydroxyarsinoyl) butanoate] (AST-OH).

Antimicrobial Activity of Metals and Metalloids.

Competition shapes evolution. Toxic metals and metalloids have exerted selective pressure on life since the rise of the first organisms on the Earth, which has led to the evolution and acquisition of resistance mechanisms against them, as well as mechanisms to weaponize them. Microorganisms exploit antimicrobial metals and metalloids to gain competitive advantage over other members of microbial communities.

Selenite Inhibits Notch Signaling in Cells and Mice.

Selenium is an essential micronutrient with a wide range of biological effects in mammals. The inorganic form of selenium, selenite, is supplemented to relieve individuals with selenium deficiency and to alleviate associated symptoms. Additionally, physiological and supranutritional selenite have shown selectively higher affinity and toxicity towards cancer cells, highlighting their potential to serve as chemotherapeutic agents or adjuvants.

Organoarsenicals inhibit bacterial peptidoglycan biosynthesis by targeting the essential enzyme MurA.

Trivalent organoarsenicals such as methylarsenite (MAs(III)) are considerably more toxic than inorganic arsenate (As(V)) or arsenite (As(III)). In microbial communities MAs(III) exhibits significant antimicrobial activity. Although MAs(III) and other organoarsenicals contribute to the global arsenic biogeocycle, how they exert antibiotic-like properties is largely unknown.

Semisynthesis of the Organoarsenical Antibiotic Arsinothricin.

Arsinothricin [AST ()], a new broad-spectrum organoarsenical antibiotic, is a nonproteinogenic analogue of glutamate that effectively inhibits glutamine synthetase. We report the chemical synthesis of an intermediate in the pathway to , hydroxyarsinothricin [AST-OH ()], which can be converted to by enzymatic methylation catalyzed by the ArsM As(III) -adenosylmethionine methyltransferase. This is the first report of semisynthesis of , providing a source of this novel antibiotic that will be required for future clinical trials.

Removal of As(III) from Water Using the Adsorptive and Photocatalytic Properties of Humic Acid-Coated Magnetite Nanoparticles.

The oxidation of highly toxic arsenite (As(III)) was studied using humic acid-coated magnetite nanoparticles (HA-MNP) as a photosensitizer. Detailed characterization of the HA-MNP was carried out before and after the photoinduced treatment of As(III) species. Upon irradiation of HA-MNP with 350 nm light, a portion of the As(III) species was oxidized to arsenate (As(V)) and was nearly quantitatively removed from the aqueous solution.

Lithium promotes malignant transformation of nontumorigenic cells in vitro.

Because of the deficiency of water caused by the regional disparities of rainfall due to global warming, attention has been given to the use of well water as drinking water in developing countries. Our fieldwork study in Afghanistan showed that there was a maximum value of 3371 μg/L and an average value of 233 μg/L of lithium in well drinking water. Since the level of lithium in well water is higher than the levels in other countries, we investigated the health risk of lithium.

Reduction of Organoarsenical Herbicides and Antimicrobial Growth Promoters by the Legume Symbiont .

Massive amounts of methyl [e.g., methylarsenate, MAs(V)] and aromatic arsenicals [e.

Arsinothricin, an arsenic-containing non-proteinogenic amino acid analog of glutamate, is a broad-spectrum antibiotic.

The emergence and spread of antimicrobial resistance highlights the urgent need for new antibiotics. Organoarsenicals have been used as antimicrobials since Paul Ehrlich's salvarsan. Recently a soil bacterium was shown to produce the organoarsenical arsinothricin.

The antibiotic action of methylarsenite is an emergent property of microbial communities.

Arsenic is the most ubiquitous environmental toxin. Here, we demonstrate that bacteria have evolved the ability to use arsenic to gain a competitive advantage over other bacteria at least twice. Microbes generate toxic methylarsenite (MAs(III)) by methylation of arsenite (As(III)) or reduction of methylarsenate (MAs(V)).

Directed Evolution of for Increased Selenium Accumulation.

Selenium-enriched yeast (selenium yeast) are one of the most popular sources of selenium supplementation used in the agriculture and human nutritional supplements industries. To enhance the production efficiency of selenium yeast, we sought to develop a method to identify, and ultimately select for, strains of yeast with enhanced selenium accumulation capabilities. Selenite resistance of four genetically diverse strains of was assayed in various conditions, including varying carbon sources, nitrogen sources, and phosphate amounts, and they were correlated with selenium accumulation in a commercially relevant selenium-containing growth medium.

A disadvantageous effect of adsorption of barium by melanin on transforming activity.

At present, beneficial effects of melanin and harmful effects of barium have been reported. However, little is known about the adsorption of barium, and even less is known about the biological significance of adsorption of barium by melanin. In this study, we showed that there was a strong correlation between the digitalized level of skin pigmentation and barium level in murine skin compared to the correlations between skin pigmentation level and levels of homologous elements of barium (magnesium, calcium and strontium).

Hepatic ZIP8 deficiency is associated with disrupted selenium homeostasis, liver pathology, and tumor formation.

Zrt/Irt-like protein 8 (ZIP8) (encoded by Slc39a8) is a multifunctional membrane transporter that influxes essential metal cations Zn, Mn, Fe, and nonmetal inorganic selenite (HSeO). Physiological roles of ZIP8 in different cell types and tissues remain to be elucidated. We aimed to investigate ZIP8 functions in liver.

A comprehensive study including monitoring, assessment of health effects and development of a remediation method for chromium pollution.

Chromium (Cr) pollution caused by wastewater from tanneries is a worldwide environmental problem. To develop a countermeasure, we performed a comprehensive study using Hazaribagh, the tannery area in Dhaka City, Bangladesh, as a model. Our environmental monitoring indicated that the soluble form of Cr, but not barium or arsenic, in Buriganga River is derived from Hazaribagh.