硫酸盐还原一甲烷化两相厌氧消化系统运行工艺条件的研究

以合成废水为基质,研究了采用硫酸盐还原-甲烷化两相厌氧新型工艺处理含高浓度硫酸盐有机废水的系统运行工艺条件.结果表明,酸化-硫酸盐还原反应器的适宜pH为6.5-7.0;500mg/l的S~(2-)使SRB的硫酸盐还原活性下降;208mg/l的[H_2S]_L抑制MPB活性的95.4%;推导出估算气提塔出水回流比R的模型;以得到的工艺条件为依据处理了含19200mg/1的SO_4~(2-)和29400mg/l COD的味精废水.     

Structure and properties of poly(3-hydroxybutyrate-co-4-hydroxybutyrate) produced by Alcaligenes latus

Summary Random copolymers of 3-hydroxybutyrate (3HB) and 4-hydroxybutyrate (4HB) with a wide range of compositions varying from 0 to 83 mol% 4HB were produced by Alcaligenes latus from the mixed carbon substrates of 3-hydroxybutyric and 4-hydroxybutyric acids. The structure and physical properties of P(3HB-co-4HB) were characterized by¹H and¹³C NMR spectroscopy, gel-permeation chromatography, and differential scanning calorimetry. The isothermal radial growth rates of spherulites of P(3HB-co-4HB) were much slower than the rate of P(3HB) homopolymer. The enzymatic degradation rates of P(3HB-co-4HB) films by a PHB depolymerase were strongly influenced by the copolymer composition.     

Quantitative contribution of the acid production to the intracellular acidification in human neutrophils stimulated by N-formyl-methionyl-leucyl-phenylalanine

A chemotactic peptide, N-formyl-methionyl-leucyl-phenylalanine (fMLP), induced an acidification of cytosol by about 0.05 pH units in 30 sec followed by an alkalinization in human neutrophils. The quantitative contribution of acid production to the acidification was studied. The superoxide (O₂ ^–) production stimulated by fMLP was not involved in the acidification because the production of acids in neutrophils from patients with chronic granulomatous disease who do not produce O₂ ^–, was the same as that in normal neutrophils. The intracellular acidification was completely inhibited by deoxyglucose, suggesting that energy metabolism enhanced upon stimulation by fMLP might be the main source of the acidification. Although enhancement of the lactate formation by fMLP was 0.8 nmol/10⁶ cells, which could lower intracellular pH by 0.08 pH units, the lactate production could not explain the initial acidification because the production of lactate started at 1 min after the stimulation while the intracellular acidification began immediately after the stimulation. Mitochondrial respiratory inhibitors such as KCN and rotenone had no effects on the fMLP-induced intracellular acidification. The fMLP-induced production of CO₂ in 30 sec through the hexose monophosphate shunt was only 2.6 pmol/10⁶ cells, which was calculated to decrease intracellular pH by only 0.0014. Thus, changes of energy metabolism induced by fMLP does not explain the acidification.Abbreviations fMLP N-formyl-methionyl-leucyl-phenylalanine - BCECF-AM 2,7-bis(carboxyethyl)carboxyfluorescein acetoxymethyl ester - PMA phorbol 12-myristate 13-acetate - CGD chronic granulomatous disease - HMP hexose monophosphate - pHi intracellular pH     

Inhibition of Taq DNA polymerase by seaweed extracts from British Columbia, Canada and Korea

Fifty-nine species of marine macrophytes from the coasts of British Columbia, Canada and Korea have been screened for the presence of PCR inhibitors, namely inhibitors of Taq DNA polymerase. Eleven of the species displayed some inhibitor activity. At the concentration of 5 μg of methanol extract in 25μL reaction mixture of PCR containing 1.5 unit of Taq DNA polymerase, one (Ulva sp.) of 8 Chlorophyta, eight (Colpomenia bullosa, Ecklonia cava, Endarachne binghamiae, Fucus distichus, Hizikia fusiformis, Sargassum confusum, Sargassum sagamianum, and Sargassum thunbergii) of 28 Phaeophyta, and one (Symphyocladia latiuscula) of 34 Rhodophyta showed inhibition in PCR amplification. In the case of the water extract, two (Cladophora columbiana, Ulva sp.) Chlorophyta, seven (Endarachne binghamiae, Fucus distichus, Hizikia fusiformis, Sargassum confusum, Sargassum sagamianum, Sargassum horneri, Scytosiphon dotyi) Phaeophyta, no Rhodophyta and one (Phyllospadix scouleri) seagrass showed inhibition in PCR amplification. the methanol fraction of Sargassum confusum and the water fraction of Fucus gardneri (mid–intertidal) have been found to inhibit PCR at level as low as 0.5 μg in 25μL of PCR reaction mixture. This revised version was published online in August 2006 with corrections to the Cover Date.     

Identification of three genetic loci controlling leaf senescence in Arabidopsis thaliana

Four mutants that show the delayed leaf senescence phenotype were isolated from Arabidopsis thaliana . Genetic analyses revealed that they are all monogenic recessive mutations and fall into three complementation groups, identifying three genetic loci controlling leaf senescence in Arabidopsis . Mutations in these loci cause delay in all senescence parameters examined, including chlorophyll content, photochemical efficiency of photosystem II, relative amount of the large subunit of Rubisco, and RNase and peroxidase activity. Delay of the senescence symptoms was observed during both age-dependent in planta senescence and dark-induced artificial senescence in all of the mutant plants. The results indicate that the three genes defined by the mutations are key genetic elements controlling functional leaf senescence and provide decisive genetic evidence that leaf senescence is a genetically programmed phenomenon controlled by several monogenic loci in Arabidopsis . The results further suggest that the three genes function at a common step of age-dependent and dark-induced senescence processes. It is further shown that one of the mutations is allelic to ein2-1 , an ethylene-insensitive mutation, confirming the role of ethylene signal transduction pathway in leaf senescence of Arabidopsis .     

Vinculin Proteolysis Unmasks an ActA Homolog for Actin-based Shigella Motility

In polarized Madin-Darby canine kidney (MDCK) cells, the transferrin receptor (TR) is selectively delivered to the basolateral surface, where it internalizes transferrin via clathrin-coated pits and recycles back to the basolateral border. Mutant tailless receptors are sorted randomly in both the biosynthetic and endocytic pathways, indicating that the basolateral sorting of TR is dependent upon a signal located within the 61–amino acid cytoplasmic domain. To identify the basolateral sorting signal of TR, we have analyzed a series of mutant human TR expressed in MDCK cells. We find that residues 19–41 are sufficient for basolateral sorting from both the biosynthetic and endocytic pathways and that this is the only region of the TR cytoplasmic tail containing basolateral sorting information. The basolateral sorting signal is distinct from the YTRF internalization signal contained within this region and is not tyrosine based. Detailed functional analyses of the mutant TR indicate that residues 29–35 are the most important for basolateral sorting from the biosynthetic pathway. The structural requirements for basolateral sorting of internalized receptors from the endocytic pathway are not identical. The most striking difference is that alteration of G₃₁DNS₃₄ to YTRF impairs basolateral sorting of newly synthesized receptors from the biosynthetic pathway but not internalized receptors from the endocytic pathway. Also, mutations have been identified that selectively impair basolateral sorting of internalized TRs from the endocytic pathway without affecting basolateral sorting of newly synthesized receptors. These results imply that there are subtle differences in the recognition of the TR basolateral sorting signal by separate sorting machinery located within the biosynthetic and endocytic pathways.     

Interaction of an adenovirus 14.7-kilodalton protein inhibitor of tumor necrosis factor alpha cytolysis with a new member of the GTPase superfamily of signal transducers.

The adenovirus (Ad) 14.7-kDa E3 protein (E3-14.7K), which can inhibit tumor necrosis factor alpha (TNF-alpha) cytolysis, was used to screen HeLa cell cDNA libraries for interacting proteins in the yeast two-hybrid system. A new member of the low-molecular-weight (LMW) GTP-binding protein family with Ras and ADP-ribosylation factor homology was discovered by this selection and has been named FIP-1 (14.7K-interacting protein). FIP-1 colocalized with Ad E3-14.7K in the cytoplasm especially near the nuclear membrane and in discrete foci on or near the plasma membrane. Its interaction with E3-14.7K was dependent on the FIP-1 GTP-binding domain. The stable expression of FIP-1 antisense message partially protected the cells from TNF-alpha cytolysis. FIP-1 was associated transiently with several unknown phosphorylated cellular proteins within 15 min after treatment with TNF-alpha. FIP-1 mRNA was expressed ubiquitously but at higher levels in human skeletal muscle, heart, and brain. In addition to homology to other LMW GTP-binding proteins, FIP-1 has regions of homology to two prokaryotic metalloproteases. However, there was no homology between FIP-1 and any of the recently isolated death proteins in the TNF-alpha or Fas/APO1 cytolytic pathway and no interaction with several members of the Bcl-2 family of inhibitors of apoptosis. These data suggest that FIP-1, as a cellular target for Ad E3-14.7K, is either a new intermediate on a previously described pathway or part of a novel TNF-alpha-induced cell death pathway. FIP-1 has two consensus sequences for myristoylation which would be expected to facilitate membrane association and also has sequences for Ser/Thr as well as Tyr phosphorylation that could affect its function.     

Methanogenesis in thermophilic biogas reactors

Methanogenesis in thermophilic biogas reactors fed with different wastes is examined. The specific methanogenic activity with acetate or hydrogen as substrate reflected the organic loading of the specific reactor examined. Increasing the loading of thermophilic reactors stabilized the process as indicated by a lower concentration of volatile fatty acids in the effluent from the reactors. The specific methanogenic activity in a thermophilic pilot-plant biogas reactor fed with a mixture of cow and pig manure reflected the stability of the reactor. The numbers of methanogens counted by the most probable number (MPN) technique with acetate or hydrogen as substrate were further found to vary depending on the loading rate and the stability of the reactor. The numbers of methanogens counted with antibody probes in one of the reactor samples was 10 times lower for the hydrogen-utilizing methanogens compared to the counts using the MPN technique, indicating that other non-reacting methanogens were present. Methanogens that reacted with the probe againstMethanobacterium thermoautotrophicum were the most numerous in this reactor. For the acetate-utilizing methanogens, the numbers counted with the antibody probes were more than a factor of 10 higher than the numbers found by MPN. The majority of acetate utilizing methanogens in the reactor wereMethanosarcina spp. single cells, which is a difficult form of the organism to cultivatein vitro. No reactions were observed with antibody probes raised againstMethanothrix soehngenii orMethanothrix CALS-1 in any of the thermophilic biogas reactors examined. Studies using 2-¹⁴C-labeled acetate showed that at high concentrations (more than approx. 1 mM) acetate was metabolized via the aceticlastic pathway, transforming the methyl-group of acetate into methane. When the concentration of acetate was less than approx. 1 mM, most of the acetate was oxidized via a two-step mechanism (syntrophic acetate oxidation) involving one organism oxidizing acetate into hydrogen and carbon dioxide and a hydrogen-utilizing methanogen forming the products of the first microorganism into methane. In thermophilic biogas reactors, acetate oxidizing cultures occupied the niche ofMethanothrix species, aceticlastic methanogens which dominate at low acetate concentrations in mesophilic systems. Normally, thermophilic biogas reactors are operated at temperatures from 52 to 56° C. Experiments using biogas reactors fed with cow manure showed that the same biogas yield found at 55° C could be obtained at 61° C after a long adaptation period. However, propionate degradation was inhibited by increasing the temperature.     

Uptake of high-density lipoprotein by Y-organs of the crab,cancer antennarius. II. formal characterization of receptor-mediation with isolated membranes

Y-organs are the ecdysial glands of crustaceans, responsible for synthesis and secretion of ecdysteroid hormones. For this purpose, the glands acquire cholesterol as obligate precursor entirely from circulating high-density lipoprotein (HDL). A preceding study provided evidence for the mechanism of acquisition: Y-organs take up cholesterol bound to HDL by an energy-requiring process, receptor-mediated absorptive endocytosis. The present study characterized the receptors involved utilizing isolated Y-organ membranes. HDL binding was saturable and specific; a dissociation constant (K_d) of 1.08 × 10^?7 M and a binding maximum at equilibrium (B_max) of 70 μg HDL protein/mg membrane protein, were obtained. Binding was decreased by protease and was dependent upon calcium. Y-organs are regulated negatively by a peptide hormone from the eystalks, molt-inhibiting hormone (MIH). Y-organ membranes from de-eyestalked crabs (MIH absent) exhibited the same K_d value as membranes from intact crabs, but a B_max 17% higher. Thus, MIH activity apparently does not change the binding affinity of HDL, but decreases the number of binding sites. These results agree with our previous findings that MIH depresses ecdysteroid synthesis in part by inhibiting cholesterol uptake. Generally, Y-organ cells appear to contain receptors for HDL that are of high affinity and high binding capacity, similar to the characteristics reported for the binding of insect HDL (vitellogenin) to fat bodies and oocytes. © 1995 Wiley-Liss, Inc.