High Levels Of Hydrogen Sulfide Research Articles

The Liver as a Central Regulator of Hydrogen Sulfide

The liver is likely exposed to high levels of hydrogen sulfide (H2S) from endogenous hepatic synthesis and exogenous sources from the gastrointestinal tract. Little is known about the consequence of H2S exposure on the liver or hepatic regulation of H2S levels. We hypothesized that the liver has a high capacity to metabolize H2S and that H2S oxidation is decreased during sepsis, a condition in which hepatic O2 is limited and H2S synthesis is increased. Using a nonrecirculating isolated and perfused liver system, we demonstrated rapid hepatic H2S metabolism up to an infusion concentration of 200' μM H2S. Hydrogen sulfide metabolism was associated with an increase in O2 consumption from a baseline 96.7 ± 7.6 μmol O2/min/kg to 109 ± 7.4 μmol O2/min/kg at an infusion concentration of 150 μM H2S (P < 0.001). Removal of O2 from the perfusate decreased H2S clearance from a maximal 97% to only 23%. Livers isolated from rats subjected to cecal ligation and puncture (CLP) did not differ significantly from control livers in their capacity to metabolize H2S, suggesting that H2S oxidation remains a priority during sepsis. To test whether H2S induces O2 consumption in vivo, intravital microscopy was utilized to monitor the oxygen content in the hepatic microenvironment. Infusion of H2S increased the NADH/NAD+ ratio (645 gray-scale-unit increase, P = 0.035) and decreased hepatic O2 availability visualized with Ru(Phen)3(2+) (439 gray-scale-unit increase, P = 0.040). We conclude that the liver has a high hepatic capacity for H2S metabolism. Moreover, H2S oxidation consumes available oxygen and may exacerbate the tissue hypoxia associated with sepsis.

Interior Proliferation and its Improvement of Hydrogen Sulfide from Hot Springs Gas

For a healthy environment for hot spring recreation, this study discussed the diffusion in the bathroom of hydrogen sulfide gas from hot sulfur springs for an improvement of this harmful situation. Based on empirical measurements and then comparing the results with CFD simulation, the analysis exposed the distribution status of indoor hydrogen sulfide and its diffusion behavior. Results indicate that sulfur springs produce high levels of hydrogen sulfide that are hazardous. And the high concentrations can be improved under ideal ventilation, which was determined by the air exchange rate, flow field efficiency, turbulence and vortex phenomena.

Effect of long-term exposure to sulfides on taurine transporter gene expression in the gill of the deep-sea mussel Bathymodiolus platifrons, which harbors a methanotrophic symbiont

Seawater around deep-sea hydrothermal vents and cold seeps contain high levels of hydrogen sulfide, which is toxic to most animals. Invertebrates inhabiting these environments have been reported to accumulate high levels of thiotaurine, a sulfur-containing amino acid. Thiotaurine is likely to play an important role in sulfide detoxification, but its functions in the detoxification process are still unknown. We cloned methane-seep mussel Bathymodiolus platifrons cDNA encoding the taurine transporter (TAUT), which transports thiotaurine and its precursors across the cell membrane. Phylogenetic analyses revealed that the predicted peptide formed a clade with the TAUTs of shallow-water mussel Mytilus galloprovincialis and the hydrothermal vent mussel Bathymodiolus septemdierum that harbors thioautotrophic bacteria. We then reared B. platifrons in the presence or absence of Na2S and quantified TAUT mRNA using a real-time PCR system. The amount of TAUT mRNA in the gills of B. platifrons increased with rearing in the presence of Na2S for 69 days, but no change was observed in the absence of sulfide. These results suggest that TAUT plays an important role in sulfide detoxification, even in species that do not harbor thioautotrophic bacteria. The TAUT mRNA level was variable in the mantle and low in the foot throughout the entire rearing period, regardless of the presence/absence of sulfide, suggesting that TAUT gene expression is regulated differentially in each tissue.

Hydrogen Sulfide Increases Hypoxia-inducible Factor-1 Activity Independently of von Hippel–Lindau Tumor Suppressor-1 inC. elegans

Rapid alteration of gene expression in response to environmental changes is essential for normal development and behavior. The transcription factor hypoxia-inducible factor (HIF)-1 is well known to respond to alterations in oxygen availability. In nature, low oxygen environments are often found to contain high levels of hydrogen sulfide (H(2)S). Here, we show that Caenorhabditis elegans can have mutually exclusive responses to H(2)S and hypoxia, both involving HIF-1. Specifically, H(2)S results in HIF-1 activity throughout the hypodermis, whereas hypoxia causes HIF-1 activity in the gut as judged by a reporter for HIF-1 activity. C. elegans require hif-1 to survive in room air containing trace amounts of H(2)S. Exposure to H(2)S results in HIF-1 nuclear localization and transcription of HIF-1 targets. The effects of H(2)S on HIF-1 reporter activity are independent of von Hippel-Lindau tumor suppressor (VHL)-1, whereas VHL-1 is required for hypoxic regulation of HIF-1 reporter activity. Because H(2)S is naturally produced by animal cells, our results suggest that endogenous H(2)S may influence HIF-1 activity.

INDUÇÃO DE NECROSE CEREBROCORTICAL EM BEZERROS COM DIETA RICA EM ENXOFRE

Polioencephalomalacia (PEM) is a common degenerative neurologic disease of ruminants around the world. This study evaluates clinical parameters, ruminal hydrogen sulfide concentrations and histopathological features of 6 calves weighing 120 kg and fed sulphur supplements with 0,5% of diet dry matter. Body temperature measurements as well as respiratory and cardiac rates remained within the normal range. Ruminal hydrogen sulfide levels increased after ingestion of the experimental diet. One animal showed severe neurologic signs. Necropsy findings of 2 calves revealed necrosis of cerebrocortical neurons. Clinical and histopathological analyses reported high levels of hydrogen sulfide, confirming the induction of neuronal necrosis in calves with dietary supplementation of sulphur.

Microbial ecology of submerged marine caves and holes characterized by high levels of hydrogen sulphide

Submarine caves, cavities and niches characterised by H2S elevated concentrations are particularly interesting for their inhabiting microflora as well as for the overall chemical, geological and biological parameters. These ecosystems are usually populated by well adapted living forms, physically distributed following the in situ concentration and gradient of micronutrients, O2 and H2S, and also according to the values of temperature and pH. The biota is primarily characterised by prokaryotes (both autotrophic and heterotrophic) adapted to anoxic and/or microaerophilic condition and capable to form extensive biofilms on the rocky surfaces and even on the bottom sediment. These habitats can be defined as extreme, because the scarcity or absence of solar irradiation, the chemo-physical traits and the fact that specialised prokaryotes are often the only inhabitants. This review is focused on the microbial ecology of marine caves and holes characterised by high levels of hydrogen sulphide. Ecological and geological data are already available but very few insights as far as regard microbiology were achieved in order to describe these fascinating habitats. The autochthonous mesophilic and thermotolerant microorganisms living in these caves may have interesting physiological traits and eventually may lead to potential application in biotechnological processes.

Influence of male competition on male mating behaviour in the cave molly, Poecilia mexicana

In many species, male mating behaviour is correlated with male body size, with large males often being preferred by females. Small surface-dwelling Poecilia mexicana males compensate for this disadvantage by being more sexually active and using sneaky copulations. In a cave-dwelling population, however, small males do not show this behaviour. Do small males alter their behaviour in the presence of a large rival? Here, we investigated the influence of male competition on male mating behaviour in the cave form. Two males of different sizes were mated with a female either alone or together with the other male. No aggressive interactions were observed between either fish. There was no statistically significant difference in the frequency of sexual behaviours between the two treatments. In both treatments, large males were more sexually active than small males. Thus, small cave molly males do not switch to an alternative mating behaviour in the presence of a larger rival. Possibly, the extreme environmental conditions in the cave (e.g. low oxygen content and high levels of hydrogen sulphide) favour saving energetic costs, resulting in the absence of alternative mating behaviour in small males.

Spermiogenesis and modified sperm morphology in the "seepworm" Methanoaricia dendrobranchiata (Polychaeta: Orbiniidae) from a methane seep environment in the Gulf of Mexico: implications for fertilization biology.

Spermatogenesis and mature sperm morphology have been described along with limited observations of the ovary in Methanoaricia dendrobranchiata, an orbiniid polychaete associated with dense populations of the mussel Bathymodiolus childressi at brine pools on the Louisiana slope, Gulf of Mexico. The species is gonochoric with gonads serially repeated in numerous segments and each associated with a nexus of blood vessels at the base of the parapodia. In the female, synchronous, intraovarian egg development occurs with the release from the ovary of large, yolky eggs into the coelom at first meiotic metaphase. Sperm develop in the coelom as free-floating, plasmodial clones interconnected via an anuclear cytophore. At the end of spermiogenesis, mature spermatozoa float freely in the coelom. The mature spermatozoon differs significantly from that of shallow-water orbiniid species by possessing an elongated nucleus and a greatly elongated and curved acrosome reaching 19.5 microm in length. The spermatozoon resembles an ent-aquasperm and may not fertilize the eggs directly in seawater in the classical manner. We hypothesize that the unusual spermatozoon morphology in this species has evolved due to the hypoxic environment in which the adults live and that fertilization biology is likely modified in some way to minimize sperm exposure to high levels of hydrogen sulfide. An analysis of life-history features in shallow-water orbiniids is used to infer reproductive features in M. dendrobranchiata that could not be directly documented.

Volatile sulphur compounds in wines related to yeast metabolism and nitrogen composition of grape musts

The influence of nitrogen compounds in grape musts on the content of sulphur compounds of wines was studied. Different vinifications were performed with the addition of methionine (20 mg l −1) and/or cysteine (40 mg l −1) to grape musts before alcoholic fermentation. Six grape musts, with different nitrogen composition, from cultivars of the ‘Vinhos Verdes’ Region, in Portugal, were used. Addition of methionine to grape musts enhanced the content of wines in 3-(methylthio)-1-propanol, acetic acid-3-(methylthio)propyl ester, 3-(methylthio)propionic acid and some unidentified sulphur compounds. Increase of cysteine concentration in musts led to the production of wines with high levels of hydrogen sulphide and cis-2-methyltetrahydro-thiophene-3-OL and also unidentified sulphur compounds; however, the content of 3-(methylthio)propionic acid in the wines decreased considerately with the addition of cysteine to grape musts. This work showed that cultivars from the Vinho Verde Region show different sulphur compound contents. Avesso wines, elaborated from grape musts with low amino acids level, presented the highest total sulphur compounds content. Wines from Azal branco and Alvarinho were characterised by high contents of 4-(methylthio)-1-butanol and 3-(methylthio)propionic acid, respectively. A high content of N-(3-(methylthio) propyl)-acetamide and dimethylsulphone characterise the Loureiro wines. In contrast, Trajadura wines, produced from a must rich in amino acids, presented a low total sulphur compounds content; however, these wines were also characterised by high concentrations of 4-(methylthio)-1-butanol, acetic acid-3-(methylthio)propyl ester and hydrogen sulphide.

Exploitation of a chemosynthetic food resource by the polychaete Capitella sp.

In organically enriched sediments of coastal areas, sulfate-reducing bacteria decom- pose organic matter anaerobically, producing high levels of hydrogen sulfide. Chemoautotrophic sul- fur-oxidizing bacteria proliferate at the sulfide/oxygen interface and use hydrogen sulfide as an elec- tron donor. A few species of small polychaete worms, including Capitella sp. I, often dominate the macrofaunal benthic communities in such sulfide-rich environments in the organically enriched sed- iments. In this study, we conducted 2 laboratory experiments to determine whether Capitella sp. I can benefit trophically through the exploitation of the organic matter chemosynthetically produced by sulfur-oxidizing bacteria. In the first experiment, we reared juveniles of Capitella sp. I with natural sediment of very low organic content, with no additional organic matter, under dark conditions, and exposed them to 3 different levels of sodium sulfide. The worms reared in the sulfide treatments showed better survival, enhanced growth and reproduction. They had lower δ 13 C values (-24.3‰, mean) than control worms (-20.1‰, mean) and the sediments in which the worms were cultured (-21.4‰, mean). The distinctive δ 13 C signature of the worms in the sulfide treatments indicates that they did not share the same carbon source as the control worms. The second experiment was done in the same manner as the first, but the carbonate in the water was replaced with 13 CO2 in order to trace the autotrophic fixation of carbon dioxide by chemosynthetic bacteria occurring within the sedi- ments. The results indicate that fixation of 13 CO2 was promoted in sediments with Na2S amendments, and further enhanced by the presence of Capitella sp. I. The worms in these sediments had extremely high δ 13 C values (+5218.2‰). The results of this study introduce the possibility of enhanced survival and growth of Capitella sp. I in sulfide-rich environments in the organically enriched sediments, facilitated by its utilization of a novel source of organic matter.

GROWTH AND CONDITION OF SEEP MUSSELS (BATHYMODIOLUS CHILDRESSI) AT A GULF OF MEXICO BRINE POOL

The banks of Brine Pool NR1, a brine-filled pockmark in the Gulf of Mexico, are host to a population of Bathymodiolus childressi, a hydrocarbon seep mussel with methanotrophic endosymbionts. The mussel community surrounds the pool, covering an area of ∼540 m2 and can be divided into two distinct zones separated by a transitional area. The inner zone extends inward from the edge of the pool ∼1 m. The water among the mussels in this zone has high methane concentrations (>200 μmol/L) and moderate oxygen concentrations (nondetectable to 161 μmol/L). Hydrogen sulfide was rarely detected in this zone. The outer zone extends ∼1 m inward from the outer edge of the mussel bed. This zone also has high methane concentrations in the water among the mussels (>200 μmol/L), but lower average oxygen levels and areas with very high levels of hydrogen sulfide. The two zones are linked with a transitional area, the middle zone, ranging in width from 1 to 4 m, where intermediate environmental conditions are found. The inner zone was relatively homogenous, while spatial heterogeneity was high in the middle and outer zones, both in the characteristics of the mussel population and in their environment. Size-frequency distributions indicate that the inner zone is an area of active recruitment, with very little recruitment occurring in either the middle or outer zones. Physiological condition indices of the mussels were significantly higher in the inner zone than in the outer zone in some years. Comparisons of growth parameters also indicate better growth conditions in the inner zone. Physiological condition and growth did not change between the first two years of the study. However, a significant change in both was detected between 1994 and 1995, suggesting that this deep-sea community is exposed to an unexpected temporal variability in environmental conditions.

Effects of repeated exposures of hydrogen sulphide on rat hippocampal EEG

Exposure to high levels of hydrogen sulphide (H 2S) in humans has been associated with a number of respiratory and neurological symptoms. Acute toxicity following exposure to high concentrations is well-documented, however, there is little scientific information concerning the effects of exposure to low concentrations. The effects of low levels of H 2S on electroencephalographic (EEG) activity in the hippocampus and neocortex were investigated on the freely moving rat (Sprague-Dawley). Hippocampal electrodes were implanted in the dentate gyrus (DG) and CA1 region. Activity was recorded for 10 min just prior to H 2S exposure in the presence of air (pre-exposure). Rats were exposed to H 2S (25, 50, 75 or 100 ppm) for 3 h/day; data was collected during the final 10 min of each exposure. The total power of hippocampal theta activity increased in a concentration-dependent manner in both DG and CA1; repeated exposures for 5 consecutive days resulted in a cumulative effect that required 2 weeks for complete recovery. The effects were found to be highly significant at all concentrations within subjects. Neocortical EEG and LIA (Large Amplitude Irregular Activity) were unaffected. The results demonstrate that repeated exposure to low levels of H 2S can produce cumulative changes in hippocampal function and suggest selectivity of action of this toxicant.

Efficiency of the decomposition of organic matter, loaded on the sediment, as a result of the biological activity of Capitella sp. I

Over the past three decades, fish farming in net pens has been extensively developed in Japanese coastal seas. Recently, however, many fish farms have suffered from organic pollution of the bottom environment, due to the vast discharge of organic matter from the fish farms themselves. During the summer, the bottom water in organically polluted areas is apt to be anoxic. High levels of hydrogen sulphide are often produced in the organically polluted sediment. We have attempted to treat the organically polluted sediment by exploiting the biological activities of a deposit-feeding polychaete, Capitella sp. I. In experiments in the laboratory, the size of colonies of this species increased very rapidly, and the organic matter that was loaded on the sediment was very efficiently decomposed. The proliferating colonies also promoted the oxidation of the reduced sulphides in the sediment. The results of this study indicate that dense patches of more than 59 000 individuals m −2 have the potential to exhaust the organic matter loaded on the seabed at a depth of 10 m below the net pens used for fish culture. The ability of a Capitella population to decompose organic matter may be applicable to the treatment of organically polluted sediment that accumulates below the fish farms.

Thiobacillus neopolitanus implicated in the degradation of concrete tanks used for potable water storage

Following commissioning of a small water treatment plant, the pH of its finished water dropped by 0.5 units during the fourth year. Concrete surfaces of storage tanks were degrading and submerged steel surfaces became colonized with large rust-coloured nodules. Changes in chemical additions along with engineering changes did not improve the symptoms. Raw water was taken from a eutrophic lake and contained high levels of hydrogen sulphide. Microbiological analyses of various plant sites yielded the presence of Thiobacillus neopolitanus and apparent autotrophic Pseudomonas spp. After evaluating the results a number of modifications were recommended and the major one was that a low hydrogen sulphide containing source water should be used. To address this recommendation the water treatment plant now uses water from a moderately sized river resulting in lower in-plant acid production and a better finished water.

Beach erosion and geochemical factors: Influence on spawning success of horseshoe crabs (Limulus polyphemus) in Delaware Bay

Horseshoe crab spawning activity is spatially patchy within the Delaware Estuary. This study investigated the importance of geochemical and erosional factors to the selection of breeding beaches. Two sandy beaches in Cape May county, New Jersey, USA, were studied; one beach had been subjected to considerable erosion, exposing underlying peat; the second beach, less than 1 km away, had only traces of peat. Reduced sediments with high levels of hydrogen sulfide were correlated with the presence of peat, and significantly fewer crabs utilized sediments in the proximity of peat beds for reproduction. The lower spawning activity on the beach in the vicinity of exposed peat, suggests that crabs may detect, at a distance, the nature of sediments and the quality of beach for spawning activity. Active salt marsh and peat-bank sediments dominate the upper bay shore; these sediments are unsuitable, or at best marginal, for horseshoe crab reproduction. Extensive bulkheading of eroding sandy beach along several New Jersey shore communities has further restricted the availability of suitable spawning habitat, making the remaining stretches of optimal sandy beach critical to the reproductive success of this species.

Geochemical and sedimentological considerations of a permanently anoxic fjord — Framvaren, south Norway

Framvaren, a fjord in south Norway, is an example of extreme anoxia, due to the geomorphological features (sill depth ∼ 2 m, basin depth ∼ 180 m). The postglacial history of Framvaren is outlined emphasizing the preservation of environmental changes in the properties of the water and the sediments. High levels of hydrogen sulfide in the water (170–180 ml l −1 or 7–8 mM H 2S) dense populations of photosynthetic bacteria at the redox boundary (total number ∼ 3 × 10 6ml −1), metal-sulfide formation in the anoxic water (e.g. framboidal pyrite and zinc sulfide) and organic-rich bottom sediments with high metal content (e.g. > 1000 ppm Zn), are typical examples. The rate of sedimentation is estimated in three independent ways suggesting an average, annual flux of ∼ 100 g m −2 yr −1 in the central basin of Framvaren. Fluxes of organic matter and zinc to the sediments are calculated and compared with potential sources.

Desalting 36,000 ppm well water with electrodialysis — a 5-year report

The author reported on the design and initial operation of this unidirectional electrodialysis plant in July 1977. The 36,000 ppm TDS well water is saturated with calcium sulfate and contains high levels of hydrogen sulfide (reported as high as 190 ppm). The 42,000 USGPD plant has now been in service for nearly 5 years and has never failed to provide the potable water needs of the desert camp that it serves. The operation of the pretreatment section of the plant has been modified to reduce the amount of lime fed to the solids contact clarifier thereby reducing the quantity of acid required for pH reduction of the feed water. The only major modification to the electrodialysis portion of the plant has been the installation of new type anion membranes. The membrane stacks are now primarily equipped with two types of anion membranes, both of which operate at a lower electrical resistance and higher ion transfer efficiency. The result of these more efficient anion membranes is a lower power consumption and higher production rate. Improvements to the electrode system have resulted in continuous membrane stack operating periods of over 6000 hours between disassemblies. Equipment to increase the capacity of the plant by 50% is scheduled for installation and start-up in 1981.

Ecologia e contribuição dos anelídeos poliquetos para a biomassa bêntica da zona das marés, no litoral norte do Estado de São Paulo

A pesquisa visou ao conhecimento das condições biológicas de algumas praias do litoral norte do Estado de São Paulo, tendo sido os poliquetos os organismos indicadores. O material estudado proveio de um total de 191 estações, distribuídas em vários níveis da zona das marés, em onze praias da Enseada do Flamengo (continente) e Enseada das Palmas (Ilha Anchieta). Em cada estação foi amostrada uma área de 1/20 m² , com uma profundidade de 10 cm e medidos a temperatura, pH, salinidade e o teor de oxigênio dissolvido da água intersticial. Simultaneamente foram coletadas amostras da água do mar ao nível da baixa-mar, para medida dos mesmos parâmetros. As amostras de sedimento colhidas entre 5 e 10 cm de profundidade, foram analisadas quanto à granulometria, porosidade, conteúdo de calcário e de matéria orgânica. Os resultados mostram que tanto a granulometria, e o teor de matéria orgânica do substrato quanto às características da água intersticial têm papel relevante no condicionamento da endofauna dessas praias. Observou-se ainda ausência de macrofauna em praias de areia grossa com arrebentação intensa. Quando a areia da praia é fina e homogênea, constitui um substrato compacto, praticamente imune a ação das vagas, Esse tipo de substrato ocorre na Praia da Enseada (no continente) e Praia Grande da Ilha Anchieta. Nessas praias constatou-se a existencia das mesmas especies de poliquetos: Nerine agilis, Arenicola brasiliensis e Diopatra cf. cuprea. Os fatores mais seletivos forama salinidade e o teor de matéria orgânica. As espécies amplamente eurialinas, como Laeonereis culveri e Nevine agilis têm uma larga distribuição na faixa entre-marés; porem alcançam sua maior concentração em áreas de salinidade abaixo de 10‰. A Praia do Saco da Ribeira mostrou ser a mais diversificada, com 20 espécies de poliquetos, entre as quais Laeonereis culveri e Diopatra cf. cuprea, que, devido à alta freqüência, contribuem significantemente para a biomassa da área. Esta praia e a da Enseada revelaram certo grau de poluição que provavelmente tem também influência marcante sobre a seleção e distribuição da fauna.