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71.
M. D. Baustian S. Q. Wang K. W. Beyenbach 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1997,167(1):61-70
Plasma and urine of toadfish (Opsanus tau) in sea water and 10% sea water were analyzed to assess responses of an aglomerular fish to hypoosmotic challenge. Following
transfer to 10% sea water, plasma osmotic pressure decreased slowly from 318 to 241 mmol · kg H2O−1, over a period of 10–15 days. Urine osmotic pressure decreased in parallel from 299 to 207 mmol · kg H2O−1, leaving urine/plasma ratios of osmotic pressure essentially unchanged. In contrast, the volume and composition of urine
changed rapidly following transfer to 10% sea water. Urine flow rate increased 110% from 3.0 to 6.3 μl · 100g−1 · h−1 and Na+ excretion increased 346%, while excretion of Mg2− and SO4
2− decreased 81% and 90%, respectively. Excretion rates for Cl− were low in seawater toadfish and decreased further in 10% sea water. An unknown sulfur-containing anion, present in the
urine of seawater toadfish, contributed significantly to the composition and ionic balance in urine of toadfish in 10% sea
water. These results suggest that the inability to produce strongly dilute urine obliges toadfish to lose salt in order to
excrete water, in hypoosmotic media. The decrease in plasma osmotic pressure may be both a strategy to reduce osmotic and
ionic gradients in dilute media and a consequence of the kidney's inability to excrete water without salt.
Accepted: 22 August 1996 相似文献
72.
73.
74.
Sulfur isotope (34S/32S) fractionation during reduction of dissolved sulfate was investigated with a growing batch culture of a thermophilic, gram-negative,
sulfate-reducing bacterium (strain MT-96) at 60 °C. The completely oxidizing strain was isolated from geothermally heated
sediments of a shallow-water hydrothermal vent in the Mediterranean Sea. The hydrogen sulfide produced in the experiments
was enriched in 32S by approximately 19‰ as compared to sulfate, which indicates that stable isotope discrimination by this thermophile is within
the range found previously for mesophilic sulfate-reducing bacteria, and only slightly higher than that observed for the thermophilic
gram-positive Desulfotomaculum nigrificans.
Received: 1 December 1998 / Accepted: 25 May 1999 相似文献
75.
Tritep Vichkovitten Marianne Holmer 《Journal of experimental marine biology and ecology》2005,316(2):183-201
The influence of seagrass Zostera marina on sediment characteristics was examined in two contrasting sediments, one organic-rich and one organic-poor. The presence of plants leads to reduced sediment redox potential in both sediment types compared to bare sediment with the largest effects in the organic-poor sediment. Z. marina stimulated the sulfate reduction rates in organic-poor sediment with ∼50% and higher pools of dissolved organic carbon (DOC) were found. In contrast, sulfate reduction rates were lower in vegetated compared to bare sites in the organic-rich sediment. Despite a low contribution of dissolved carbohydrate (DCHO) to the DOC pool (<5%), the seagrass vegetation was responsible for an increase of ∼50% in DCHO pools with a peak in the root zone suggesting that Z. marina supplied DCHO to the pore waters. The Z. marina meadows also enhanced the contribution of particulate carbohydrate (PCHO) to sedimentary particulate organic carbon (POC) pools by 6-14% compared to bare sediment. Although the PCHO pools were higher in organic-rich than organic-poor sediments, the analyses of carbohydrate composition revealed that three groups of neutral sugars including glucose, galactose and mannose+xylose were the major compounds of PCHO and contributed with >60% to sedimentary carbohydrate pools at both sites. Only glucose showed depletion with depth in the vegetated sediments, whereas the percentage of ribose and rhamnose increased indicating a selective degradation of labile carbohydrates in the meadows. Galactose and mannose+xylose appeared to represent a refractory part of carbohydrate that remained after degradation of the more labile components. The sugar content was rather constant with depth at the bare organic-rich sediment indicating that only recalcitrant carbohydrate pools were buried. There was less difference in the PCHO composition profiles between vegetated and bare organic-poor sediments. 相似文献
76.
Enhanced anaerobic biodegradation of nonylphenol ethoxylates by introducing additional sulfate or nitrate as terminal electron acceptors 总被引:1,自引:0,他引:1
Jian Lu Qiang Jin Yiliang He Jun Wu 《International biodeterioration & biodegradation》2008,62(2):214-218
The potential to enhance the anaerobic biodegradation of nonylphenol ethoxylates (NPEOs) by introducing additional sulfate or nitrate as electron acceptor was investigated. The results showed that adding nitrate or sulfate could significantly enhance the anaerobic biodegradation of NPEOs and alleviate the accumulation of their estrogenic intermediates. However, these terminal electron acceptors had no influence on the component of the anaerobic biodegradation products of NPEOs. To the best of our knowledge, it is the first report of the enhancement of anaerobic biodegradation of NPEOs by introducing additional terminal electron acceptor with relatively high redox potential. These observations have significant environmental implications in terms of the environmental behavior of NPEO contaminants in natural environment. 相似文献
77.
Tatsuya Ueki Nobuaki Furuno Qiang Xu Yuya Nitta Kan Kanamori Hitoshi Michibata 《Biochimica et Biophysica Acta (BBA)/General Subjects》2009
Background
Several species of ascidians accumulate extremely high levels of vanadium ions in the vacuoles of their blood cells (vanadocytes). The vacuoles of vanadocytes also contain many protons and sulfate ions. To maintain the concentration of sulfate ions, an active transporter must exist in the blood cells, but no such transporter has been reported in vanadium-accumulating ascidians.Methods
We determined the concentration of vanadium and sulfate ions in the blood cells (except for the giant cells) of Ascidia sydneiensis samea. We cloned cDNA for an Slc13-type sulfate transporter, AsSUL1, expressed in the vanadocytes of A. sydneiensis samea. The synthetic mRNA of AsSUL1 was introduced into Xenopus oocytes, and its ability to transport sulfate ions was analyzed.Results
The concentrations of vanadium and sulfate ions in the blood cells (except for the giant cells) were 38 mM and 86 mM, respectively. The concentration of sulfate ions in the blood plasma was 25 mM. The transport activity of AsSUL1 was dependent on sodium ions, and its maximum velocity and apparent affinity were 2500 pmol/oocyte/h and 1.75 mM, respectively.General significance
This could account for active uptake of sulfate ions from blood plasma where sulfate concentration is 25 mM, as determined in this study. 相似文献78.
Victor M. Gámez Reyes Sierra-Alvarez Rebecca J. Waltz James A. Field 《Biodegradation》2009,20(4):499-510
Citrate is an important component of metal processing effluents such as chemical mechanical planarization wastewaters of the
semiconductor industry. Citrate can serve as an electron donor for sulfate reduction applied to promote the removal of metals,
and it can also potentially be used by methanogens that coexist in anaerobic biofilms. The objective of this study was to
evaluate the degradation of citrate with sulfate-reducing and methanogenic biofilms. During batch bioassays, the citrate,
acetate, methane and sulfide concentrations were monitored. The results indicate that independent of the biofilm or incubation
conditions used, citrate was rapidly fermented with specific rates ranging from 566 to 720 mg chemical oxygen demand (COD)
consumed per gram volatile suspended solids per day. Acetate was found to be the main fermentation product of citrate degradation,
which was later degraded completely under either methanogenic or sulfate reducing conditions. However, if either sulfate reduction
or methanogenesis was infeasible due to specific inhibitors (2-bromoethane sulfonate), absence of sulfate or lack of adequate
microorganisms in the biofilm, acetate accumulated to levels accounting for 90–100% of the citrate-COD consumed. Based on
carbon balances measured in phosphate buffered bioassays, acetate, CO2 and hydrogen are the main products of citrate fermentation, with a molar ratio of 2:2:1 per mol of citrate, respectively.
In bicarbonate buffered bioassays, acetogenesis of H2 and CO2 increased the yield of acetate. The results taken as a whole suggest that in anaerobic biofilm systems, citrate is metabolized
via the formation of acetate as the main metabolic intermediate prior to methanogenesis or sulfate reduction. Sulfate reducing
consortia must be enriched to utilize acetate as an electron donor in order to utilize the majority of the electron-equivalents
in citrate. 相似文献
79.
It is well known that pulp density and particle size determine the available surface area concentration and have an influence
in the overall rate of bioleaching of minerals. As metal solubilization takes place through the surface area of the particles,
it can be expected that different combinations of pulp densities and particle sizes giving the same surface area concentration
would determine the same leaching rate. The objective of this work was to test this hypothesis on the effect of surface area
concentration, pulp density and particle size of the biooxidation of a pyritic gold concentrate by the thermophilic Archaeon
Sulfolobus metallicus in shake flasks. The gold concentrate was used at 2.5%, 5%, 10%, and 15% w/v pulp density and at four size fractions: 150–106,
106–75, 75–38 and –38 μm. Temperature was 68°C and the initial pH was 2.0. Results showed that the volumetric productivities
of iron and sulfate depend not only on the surface area concentration but also on pulp density and particle size considered
separately. These two variables not only determine surface area but also exert additional effects on the process, so the hypothesis
was not confirmed. Maximum attained iron productivity was 1.042 g/l day with the 75–38 μm fraction at 5% pulp density. Maximum
sulfate productivity was 4.279 g/l day with the 75–38 μm fraction at 10% pulp density. 相似文献
80.
Michael E. Bradley Joshua S. Rest Wen-Hsiung Li Nancy B. Schwartz 《Journal of molecular evolution》2009,68(1):1-13
The enzymes catalyzing the first two reactions in the sulfate activation pathway, ATP-sulfurylase (S) and APS-kinase (K),
are fused as ‘KS’ in animals but are fused as ‘SK’ in select bacteria and fungi. We have discovered a novel triple fusion
protein of K, S, and pyrophosphatase (P) in several protozoan genomes within the Stramenopile lineage. These triple domain
fusion proteins led us to hypothesize that pyrophosphatase enzymes and sulfate activation enzymes physically interact to impact
the thermodynamics of the sulfate activation pathway. In support of this hypothesis, we demonstrate through biochemical assays
that separately encoded KS and P proteins physically interact and that KS/P complexes activate more sulfate than KS alone.
We also conclude on the basis of phylogenetic analyses that all known KS fusions originate from a single fusion event early
in the eukaryotic lineage. Strikingly, our analyses support the same conclusion for all known SK fusions. These observations
indicate that the patchwork of fused and nonfused S and K genes observed in modern-day eukaryotes and prokaryotes are the
result of the two ancestral fusion genes evolving by an assortment of gene fissions, duplications, deletions, and horizontal
transfers in different lineages. Our integrative use of genomics, phylogenetics, and biochemistry to characterize pyrophosphatase
as a new member of the sulfate activation pathway should be effective at identifying new protein members and connections in
other molecular pathways.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.
Nucleotide sequence data reported here are available in the GenBank/DDBJ/EMBL databases under accession number EU352210. 相似文献