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At least 19 recordsLinked to original sources
PubMed2026

Microbial succession and assembly shaped by sulfur, spatial partitioning, and water flow in a volcanic acidic river of northern Patagonia.

Extreme acidic environments represent natural laboratories for investigating the mechanisms of microbial community assembly, yet the ecological processes structuring these communities remain incompletely understood. Here, we investigate how spatial partitioning, hydrodynamics, and colonization history shape microbial succession in a unique sulfur-rich, acidic river of volcanic origin in northern Patagonia. We combined 16S rRNA gene profiling and shotgun metagenomics with a multi-scale experimental framework encompassing water column fractionation and colonization assays under native and controlled conditions. Microbial diversity was strongly influenced by spatial fractionation, with free-living communities exhibiting higher richness and temporal variability than particle-associated assemblages. Water flow modulated community structure, increasing evenness in free-living fractions under high-flow conditions, but had limited impact on particle-attached communities. Colonization of sulfur-beads followed a structured successional trajectory, with autotrophic sulfur oxidizers dominating early stages and heterotrophs adapted to biofilm lifestyles increasing over time. Ex situ recolonization assays revealed strong priority effects, with initial colonizers determining successional trajectories. Turnover analyses revealed that the balance among stochastic and deterministic assembly processes shifted across communities with pronounced stochasticity in the water column and flow-dependent effects in free-living communities, while biofilm associated communities on sulfur-beads exhibited stronger contribution of deterministic selection. These ecological patterns were mirrored by functional differentiation, with gene enrichment analyses revealing adaptive signatures of substrate attachment and resource acquisition. By integrating fine-scale environmental variation with colonization dynamics, this study reveals how microscale habitat structure and temporal fluxes jointly modulate microbial community assembly rules, offering a nuanced framework to dissect ecological processes in extreme systems.

Sulfur↗
PubMedDate not supplied

Removal of hydrogen sulfide by Chlorobium thiosulfatophilum in immobilized-cell and sulfur-settling free-cell recycle reactors.

Bioconversion of hydrogen sulfide to elementary sulfur by the photosynthetic bacterium Chlorobium thiosulfatophilum was studied in immobilized-cell and sulfur-settling free-cell recycle reactors. The cells immobilized in strontium alginate beads excreted elementary sulfur and accumulated it as crystal in the bead matrices, which made it possible that the reactor broth remained clear and the light penetrated the reactor deeper than with the free cells. In comparison with the free cells, the immobilized cells required 30% less light energy at a H2S removal rate of 2 mM/(L.h) and showed an activity of 2.4 times that of the free cells. However, in 40 h after the reaction the deterioration of the H2S removal efficiency became significant due to the accumulation of sulfur in the beads. The scanning electron micrograph (SEM) and energy-dispersive X-ray spectrometer (EDS) studies showed that the sulfur in the beads existed within a layer of 0.4 mm from the bead surface. In the sulfur-settling free-cell recycle reactor, about 80% of the sulfur excreted by the free cells could be removed in a settler. The 4-L fed batch reactor with the settler improved the light transmission to result in a H2S removal rate of 3 mumol/(mg of protein.h), 50% higher than that without it. The settling recycle reactor was much better in the removal of H2S than the immobilized-cell reactor because the former was a continuous system with the constant removal of sulfur particles by settling and of spent medium by supplying fresh medium at the same rate as the filtering rate of the reactor broth, while the latter was essentially a batch system where toxic metabolites and produced sulfur could not be removed.

Air Pollutants↗
PubMed1989

A thiophilic adsorbent for the one-step high-performance liquid chromatography purification of monoclonal antibodies.

Thiophilic adsorption chromatography, developed originally by Porath and colleagues (1985, FEBS Lett. 185, 306-310) for conventional chromatographic techniques, was transformed to the HPLC mode upon preparation of new and improved sulfur-containing silica beads. The new thiophilic adsorbent is of high capacity and is suitable for the rapid and single-step purification of all subclasses of monoclonal and polyclonal antibodies. Due to its broad specificity, the thiophilic silica column is an efficient, stable, and inexpensive substitute for protein A and protein G columns used today to purify antibodies.

Adsorption↗
PubMed2002

Decorated surfaces by biofunctionalized gold beads: application to cell adhesion studies.

We describe a simple but versatile method to decorate solid surfaces randomly with colloidal gold particles to which ligands of cell receptors can be coupled to generate local attraction sites for the control of cell adhesion. A self-assembled monolayer of (3-mercaptopropyl)trimethoxysilane was deposited on glass slides. Gold beads were anchored to the functionalized surface through the sulfur group. We characterized the gold bead distribution on the functionalized surface with reflection interference contrast microscopy. The gold beads were functionalized with a disulfide-coupled cyclic pentapeptide containing an arginine-glycine-aspartic acid (RGD) tripeptide sequence which is selectively recognized by integrin receptors alpha(V)beta(3) of endothelial cells. A blocking layer of bovine serum albumin was adsorbed onto the surface to prevent non-specific binding of the cells. We demonstrate that the RGD-functionalized colloidal gold beads act as local attraction centers, mediating rapid cell anchoring on a substrate impeding cell adhesion in the absence of attraction centers. Surprisingly, microinterferometry shows that after a time delay of about 1 h, the regions of the cell surface between the gold beads form close contacts with the substrate, which is attributed to strong van der Waals attraction after escape of repeller molecules from the contact surface.

Biophysics↗
PubMed1997

Evaluation of solid-phase labels for gastric emptying studies in cats.

UNLABELLED: Development of appropriate radiolabeled diets for solid-phase gastric emptying studies in experimental animals is important for testing the effects of disease, drugs, surgical procedures and stress. This study evaluates the in vitro and in vivo stability of various radiolabels in commercially available dry, extruded and canned cat foods. METHODS: Dry, extruded cat food was labeled with 99mTc-pertechnetate, 99mTc-sulfur colloid or 99mTc-disofenin. Canned cat food was labeled with 99mTc-Dowex resin beads, 99mTc-pertechnetate, 99mTc-sulfur colloid or 99mTc-disofenin. A sample of each labeled diet and 99mTc-sulfur colloid-labeled egg was digested in water, gastric juice, intestinal juice or gastric juice followed by intestinal juice. The samples were centrifuged and the activity in the samples counted before and after removal of the supernatant. Based on in vitro results, three labeled diets were fed to 10-12 cats for in vivo testing. RESULTS: 99mTc-Dowex beads had the best labeling efficiency in vitro, but were not stable in vivo, resulting in unacceptable levels of circulating 99mTc. Technetium-99m-disofenin labeling resulted in in vitro percent solid-phase retention of 92.5% and 89.5% in water and gastric juice, respectively, for dry food and 86% and 94.9% in water and gastric juice, respectively, for canned food. CONCLUSION: Technetium-99m-disofenin is a suitable label for solidphase gastric emptying studies using commercially available cat foods.

Administration, Oral↗
PubMed2002

Biosorption of phenol from an aqueous solution by Aspergillus niger biomass.

Phenols in trace quantities are usually present in the treated effluent of many wastewater-treatment plants. Phenol contamination of drinking water even at 1 microg/l concentration can cause significant taste and odor problems. This study investigates the use of non-viable pretreated cells of Aspergillus niger to remove phenol from an aqueous solution. Five types of non-viable pretreated A. niger biomass powders were used as a biosorbent to remove phenol present in an aqueous solution at a concentration of 1,000 microg/l. Sulfuric acid-treated non-viable biomass powder, which was the most effective, was used as a biosorbent in a further study. The maximum removal of phenol was observed at an initial pH of 5.1 for the sulfuric acid-treated biomass. The adsorption of phenol by pretreated A. niger biomass was best described by the Brunauer Emmet Teller model. Desorption of phenol using distilled deionized water was found to be approximately 5% suggesting a strong biosorption by the biomass. Sulfuric acid-treated biomass beads developed through immobilization in polysulphone were used in a column study. Approximately 66% of phenol was removed in the column operated at an initial pH of 5.1 and an initial concentration of 1,000 microg/l of phenol.

Adsorption↗
PubMed1986

Evaluation of a new ammonia sampling and analytical procedure.

A new monitoring procedure is described for the collection of ammonia in the workplace environment. Sampling is conducted using air sampling tubes packed with beaded activated carbon coated with sulfuric acid. The low cationic background of this packing permits the analysis of samples to be performed by ion chromatography, a technique which offers considerable advantage over current methods used to analyze industrial hygiene samples for ammonia. Excellent precision and accuracy are demonstrated on samples collected from atmospheres containing 0.5, 1 and 2 times TLV levels of ammonia. The analytical detection limit is such that a concentration 0.05 of TLV may be detected in a 3-L air sample with less than one percent breakthrough found in a 24-L sample at TLV.

Air Pollutants, Occupational↗
PubMedDate not supplied

Evaluation of solid phase radiolabels of dog food for gastric emptying.

99mTc-Pertechnetate, 99mTc-mebrofenin, 99mTc-disofenin, 99mTc-sulfur colloid, and 99mTc-Dowex resin beads were evaluated for in vitro stability as a label for both dry extruded, and canned dog food for gastric emptying scintigraphy. A sample of each radiolabeled diet was added to water, gastric juice, intestinal juice, or gastric juice followed by intestinal juice for in vitro digestion. After a 3-hour digestion period, tubes were centrifuged and percentage solid phase retention (%SPR) was calculated. The experiment was repeated three times over a 14-day period to minimize day-to-day variation. For dry dog food, 99mTc-mebrofenin and 99mTc-disofenin had similar %SPR in water (96 and 93%, respectively) and gastric juice (>95% each) and were significantly higher than other labels. For canned dog food, mebrofenin had a 91% SPR for the water or gastric juice digestions, and 99mTc-Dowex had a %SPR of >99%. 99mTc-mebrofenin and 99mTc-Dowex were also tested in vivo, where 99mTc-Dowex had poor stability, and 99mTc-Mebrofenin had excellent stability. 99mTc-Mebrofenin is a suitable label for dog food for gastric emptying scintigraphy.

Analysis of Variance↗
PubMed1981

[Immunosorbent based on porous cellulose sphere].

The synthesis of an immunosorbent in the form of porous beads is described. The beads were prepared by emulsification of cuprammonium glucose solution in organic solvents, followed by precipitation of beads with a mixture of acetone and sulfuric acid. The product was oxidized with NaIO4 and conjugated with protein antigen or antibodies to obtain an immunosorbent fit for column chromatography. The capacity of the immunosorbent thus obtained was found to be 300-1000 mg of antibodies or 50-70 mg of antigen per 1 g of the sorbent.

Antigen-Antibody Complex↗
PubMed1998

S-Transnitrosation reactions are involved in the metabolic fate and biological actions of nitric oxide.

S-Nitrosothiols are a group of potent, bioactive compounds that form through the reaction of nitric oxide (NO) with thiols in the presence of oxygen. These compounds are naturally occurring in vivo, stabilize NO and potentiate its biological effects. S-Nitrosoglutathione is the most abundant intracellular S-nitrosothiol, and the kinetics for its formation favors de novo synthesis. In this analysis, we studied the formation of S-nitrosothiols by S-transnitrosation, or exchange of -NO for -H between sulfur atoms; we synthesized S-nitroso-glutathionyl-Sepharose 4B beads (SNO-4B) as a reagent with which to measure S-transnitrosation reactions. We detected a maximum of 1.57 +/- 0.24 pmol NO/bead (n = 5) after S-nitrosation of the beads with acidified nitrite. The stability of the S-NO bond was dependent on temperature, but not pH over the 5 to 9 range (except at pH 9 at 37 degrees ), with an estimated t1/2 of 30 hr at 22 degrees C and of approximately 2 wk at 4 degrees C. We demonstrated that SNO-4B transfers -NO to glutathione and to cysteine rapidly and in a pH-dependent manner. The initial rate of transfer of -NO from SNO-4B to glutathione at room temperature was 0.53, 3.03 and 5.14 microM/min at pH 5.0, 7.4 and 9.0, respectively (P < .05). Under the same conditions, the initial rate of -NO transfer to cysteine was 0. 72, 3.71 and 4.69 microM/min at pH 5.0, 7.4 and 9.0, respectively (P < .05). There was no appreciable S-transnitrosation between SNO-4B and bovine serum albumin. We further demonstrated that SNO-4B evokes significant vasodilator and platelet inhibitory responses in plasma-free systems and activates platelet soluble guanylyl cyclase. These data suggest a mechanism by which to explain the metabolic fate and distribution of NO among thiol pools in the vasculature, and implicate S-transnitrosation at the cell surface in NO signal transduction.

Animals↗
PubMedDate not supplied

Ocular nocardia infections with special emphasis on the cornea.

Nocardia are aerobic, gram-positive, nonmotile and branching filamentous bacteria. Corneal infection by Nocardia is rare. Trauma is the most common predisposing factor. Isolated case reports of nocardial infection associated with contact lens wear and laser in situ keratomileusis (LASIK) have been reported. The clinical picture usually consists of superficial patchy infiltrates, which may be arranged in a wreath pattern. Presence of gram-positive, branching, beaded filaments that stain with 1% acid-fast stain (using 1% sulfuric acid, modified Kinyoun's method) in smears of corneal scrapings is suggestive of nocardial infection. Nocardia grow on commonly used media as tiny, white, dry colonies. Available knowledge and clinical experience suggest that although sulfacetamide eyedrops can be tried as the initial drug, trimethoprim-sulfamethoxazole and amikacin are effective drugs. Once therapy is initiated, the infiltrate responds promptly and resolves, forming a corneal scar with or without vascularization, and good visual recovery can be expected.

Anti-Bacterial Agents↗
PubMed2003

Immobilization of Pseudomonas delafieldii with magnetic polyvinyl alcohol beads and its application in biodesulfurization.

Pseudomonas delafieldii was immobilized in magnetic polyvinyl alcohol (PVA) beads using a hydrophilic magnetic fluid, which was prepared by a co-precipitation method. The beads had distinct super-paramagnetic properties and were compared with immobilized cells in non-magnetic PVA beads. Their desulfurizing activity was increased slightly from 8.7 to 9 mmol sulfur kg(-1) (dry cell) h(-1). The main advantages was that the magnetic immobilized cells maintain a high desulfurization activity and remain in good shape after 7 times of repeated use, while the non-magnetic immobilized cells could only be used for 5 times. Furthermore, the magnetic immobilized cells could be easily collected or separated magnetically from the biodesulfurization reactor.

Bacterial Adhesion↗
PubMed1992

Suppression of pulmonary granulomatous inflammation by immunomodulating agents.

We demonstrated previously that macrophages and macrophage-derived cytokines including lymphocyte-activating factors (LAFs) play a critical role in lung granuloma formation in mice and that granulomas sizes correlated with LAF activity in the lesions. In the present study, we examined the effects of D-penicillamine (D-Pc), 2-acetylthiomethyl-3-(4-methyl-benzoyl)propionic acid (KE-298) and dexamethasone (Dex) on dextran bead-induced lung granulomas in mice. KE-298 is a newly synthesized compound containing sulfur (S) similar to D-Pc. Large granulomas developed, which reached peak intensity within 3 days and declined in size thereafter. Aqueous lung extracts of the mice contained high levels of LAF that were correlated with granuloma sizes. The lesions and local LAF activity were inhibited by administration of these agents. The most potent inhibitor was Dex. The suppressive effect of KE-298 was similar to that of D-Pc. These results suggest that suppression of granulomas may be attributed to inhibition of LAF activity/synthesis by these agents.

Animals↗
PubMed2006

Selection of thioaptamers for diagnostics and therapeutics.

Thioaptamers offer advantages over normal phosphate ester backbone aptamers due to their enhanced affinity, specificity, and higher stability, largely due to the properties of the sulfur backbone modifications. Over the past several years, in vitro thioaptamer selection and bead-based thioaptamer selection techniques have been developed in our laboratory. Furthermore, several thioaptamers targeting specific proteins such as transcription factor NF-kappaB and AP-1 proteins have been identified. Selected thioaptamers have been shown diagnostic promise in proteome screens. Moreover, some promising thioaptamers have been shown in preliminary animal therapeutic dosing to increase survival in animal models of infection with West Nile virus.

Animals↗
PubMed1983

Cell affinity chromatography with ligands immobilized through cleavable mercury-sulfur bonds.

A new methodology for cell separation by affinity chromatography is described. We have conjugated the organomercurial mersalyl to trisacryl beads bearing primary amino groups. Thiolated ligands can be immobilized on this matrix through cleavable Hg-S bonds. Two model studies of cell separation are reported: (i) concanavalin A thiolated with N-succinimidyl-3-(2-pyridyldithio)-propionate and immobilized on mersalyl-trisacryl; mouse thymocytes bound to Con A-mersalyl-trisacryl were eluted from the support by short thiol treatment which preserved cell viability; (ii) anti-dinitrophenyl antibodies modified with S-acetyl-mercaptosuccinic anhydride and immobilized on mersalyl-trisacryl; sheep erythrocytes, previously labelled with trinitrobenzene sulfonic acid, bound to this support and were easily recovered by thiol treatment without hemolysis. This methodology should overcome difficulties frequently encountered in cell affinity chromatography. Cell support multivalent interactions or high affinity of cell-ligand bindings often require drastic elution conditions which prevent viable cell recovery.

Animals↗
PubMed2004

Progress in thioaptamer development.

Thioaptamers are thiophosphate ester modified nucleic acids that are isolated via in vitro or bead-based thioaptamer selection against a target molecule such as a protein. Thioaptamers offer advantages over traditional aptamers in their enhanced affinity and specificity and higher stability, largely due to the properties of the sulfur backbone-modifications. An in vitro thioaptamer selection procedure that simultaneously selects for sequence and optimized hybrid phosphoromonothioate or phosphate backbone substitutions is outlined. A novel bead-based thioaptamer selection protocol that can produce mixed phosphorodithioate, phosphoromonothioate or phosphate hybrid backbones is also described. Several examples of thioaptamers targeting specific protein are provided. Such thioaptamers are shown to modulate protein activity in vivo.

Combinatorial Chemistry Techniques↗
PubMed1997

Separation of monoclonal antibodies from cell-culture supernatants and ascites fluid using thiophilic agarose.

A one-step purification procedure will yield monoclonal antibodies from cell-culture supernatants and ascites fluids. The chromatographic adsorbent is thiophilic argose, i.e., beaded agarose gel coupled with ligands of thiophilic nature, often with a sulfone group and a sulfur atom. The chromatographic procedure is simply adsorption, wash, elution. The procedure is simple, efficient, and inexpensive.

Antibodies, Monoclonal↗
PubMedDate not supplied

Biodegradation of hydrogen sulfide by a laboratory-scale immobilized Pseudomonas putida CH11 biofilter.

A heterotrophic Pseudomonas putida CH11 was isolated from livestock farming wastewater and applied for the treatment of H2S-containing gas. Extensive tests including removal characteristics, metabolic products, and removal efficiencies of H2S by P. putida CH11 were examined in batch and continuous systems. The optimum pH required to remove hydrogen sulfide was found in the range of 6-8. The maximum removal rate and the saturation constant were calculated to be Vm = 1.36 g S/day.kg dry bead and Ks = 45.9 ppm, respectively. The main metabolic product of H2S oxidation was determined to be elemental sulfur. When P. putida CH11 was immobilized within Ca alginate, the cells exhibited high H2S removal efficiency, in excess of 96%, at concentration of hydrogen sulfide from 10 to 150 ppm (flow rates of 36 and 72 L/h). These results suggest that P. putida CH11 immobilized within Ca alginate has the potential to be used as a H2S removal agent.

Air Pollutants↗