Use of response surface methodology for selection of nutrient levels for culturing Paecilomyces variotii in eucalyptus hemicellulosic hydrolyzate

Eucalyptus hemicellulose was hydrolyzed by treating eucalyptus wood chips with sulfuric acid. The hydrolyzate was used as the substrate to produce single-cell protein by growing Paecilomyces variotii IOC-3764 for 72 or 96 h. The influences of rice bran, ammonium sulfate and fermentation time were verified by a 23 full-factorial central composite design. At the optimum process conditions, the cell concentration was 12.06 g/l, which was obtained when the microorganisms were cultivated for 89 h in a medium composed of 10 g/l rice bran, 2.0 g/l nitrogen and 1.1 g/l sodium phosphate. The mathematical model Y = 10.65 + 2.40X2 + 2.36X3 + 1.16X2X3 - 2.10X2(2) - 1.06X3(2) describes biomass production by P. variotii in eucalyptus hemicellulosic hydrolyzate with a determination coefficient of R2 = 0.9561, where X2 and X3 are ammonium sulfate and fermentation time, respectively.     

Calcium binding and induction of conidiation in protoplasts of Penicillium cyclopium

Cell wall-free protoplasts of P. cyclopium could regenerate a cell wall and form mycelia in liquid culture with high rates of viability. When calcium was added to the medium, protoplasts displayed biphasic accumulation with an immediate metabolism-independent adsorption phase, followed by slow metabolism-dependent uptake.Exposure of the protoplasts to Ca²⁺ for periods of 2 min, followed by incubation in calcium-free medium for 24 hours, was sufficient to induce conidiation with morphogenetic events parallel to those found in cultures containing calcium throughout the incubation period, and similar to those reported in cultures inoculated from conidia.The conidiation event caused by short exposure to calcium could be reversed, within 2 hours of Ca²⁺ addition, by a brief treatment with the specific calcium chelating agent BAPTA (100 M), which removed 65 to 75% of the total cell calcium.The results implicate the membrane-bound calcium fraction in the process of conidiation induction.     

Equilibrium isotherm studies for the uptake of cadmium and lead ions onto sugar beet pulp

The adsorption of Cd2+ and Pb2+ on sugar beet pulp (SBP), a low-cost material, has been studied. In the present work, the abilities of native (SBP) to remove cadmium (Cd2+) and lead (Pb2+) ions from aqueous solutions were compared. The (SBP) an industrial by product and solid waste of sugar industry were used for the removal of Cd2+ and Pb2+ ions from aqueous water. Batch adsorption studies were carried out to examine the influence of various parameters such as initial pH, adsorbent dose, initial metal ion concentration, and time on uptake. The sorption process was relatively fast and equilibrium was reached after about 70 min of contact. As much as 70-75% removal of Cd2+ and Pb2+ ions for (SBP) are possible in about 70 min, respectively, under the batch test conditions. Uptake of Cd2+ and Pb2+ ions on (SBP) showed a pH-dependent profile. The overall uptake for the (SBP) is at a maximum at pH 5.3 and gives up to 46.1 mg g(-1) for Cd2+ and at pH 5.0 and gives 43.5 mg g(-1) for Pb2+ for (SBP), which seems to be removed exclusively by ion exchange, physical sorption and chelation. A dose of 8 gL(-1) was sufficient for the optimum removal of both the metal ions. The Freundlich represented the sorption data for (SBP). In the presence of 0.1M NaNO3 the level of metal ion uptake was found to reach its maximum value very rapidly with the speed increasing both with the (SPB) concentration and with increasing initial pH of the suspension. The reversibility of the process was investigated. The desorption of Cd2+ and Pb2+ ions which were previously deposited on the (SBP) back into the deionised water was observed only in acidic pH values during one day study period and was generally rather low. The extent of adsorption for both metals increased along with an increase of the (SBP) dosage. (SBP), which is cheap and highly selective, therefore seems to be a promising substrate to entrap heavy metals in aqueous solutions.     

Cell death in cultured human Saos2 osteoblasts exposed to low-density lipoprotein

Osteoporosis (OP) and atherosclerotic-cardiovascular diseases (and possibly dementia) constitute emerging age-related co-morbidity states that might share risk factors. Blood-born lipids, like LDL involved in atherosclerosis and apolipoprotein-E4 (ApoE4) involved in dementia, may also be implicated in development of OP. We examined osteoblast cell lines as a culture model for OP by exposure to lipoproteins. ApoE expression in Saos2 and U2OS osteoblasts was confirmed by PCR. ApoE4 did decrease cell counts relatively to ApoE3, especially in Saos2 cells in which it was less selective for cells with higher alkaline phosphatase (ALP, an osteoblast marker) activity than ApoE3. This associates with ApoE4, being a risk factor for both dementia and OP. Saos2, but not U2OS, showed a decrease in cell counts after 48 h exposure to native LDL (NLDL). Both cell lines had decreased cell counts already after 24 h when exposed to oxidized-LDL (OxLDL) for which Saos2 also showed a higher sensitivity than U2OS. Exposure of Saos2 to both, OxLDL at low concentration (5 microg/ml) and NLDL revealed a shrunken size cell fraction of 17-23% on the fluorescence-activated cell sorter (FACS) analysis. Such shrunken cell fraction was not seen when Saos2 cells were exposed to 50 microg/ml of OxLDL or to OxLDL combined with 10 nM dexamethasone (DEX, a stimulator of osteoprogenitor differentiation). DEX treatment has lysed the cells earlier than 24 h post exposure and has selected more resistant cells that did not show apoptotic shrinkage in the FACS analysis done after 24 h. We interpret this as a failure to detect the apoptotic cell fraction due to their lysis prior to the FACS analysis. Western blots performed at different time points (10 min, 30 min, 4 h, 24 h, and 48 h) under OxLDL + DEX revealed a fall in the positive regulator of pp60Src-kinase phosphotyrosine (pY)418 relative to the DEX controls during the first 4 h. This is consistent with DEX osteogenic induction, known to be negatively regulated by c-Src, although the pY418/pY529 ratios (negative/positive kinase regulation) fell only at the 10 min time point. Contrarily the pY418/pY529 ratio increased, relative to untreated controls, under 5 microg/ml and 50 microg/ml of NLDL at the 4 h time point and under 50 microg/ml NLDL only at the 10 min time point, being consistent with the ability of a higher dose of LDL to antagonize osteoblast differentiation. This could be even more acceptable if the NLDL would have become minimally oxidized during its long purification procedure. Under NLDL, the Bcl-2/Bax ratio was pro-apoptotic at 10 min, 30 min, and 4 h only under 50 microg/ml, whereas under OxLDL + DEX it was pro-apoptotic only after 4 h suggesting that additional pathways contribute to cell death. These results indicate that lipid effects on human osteoblast lines in culture may be used as a model to identify molecular targets shared between OP and atherosclerosis for intervention in this co-morbidity.     

Removal of Pb2+ and Ni2+ by bio-sludge in sequencing batch reactor (SBR) and granular activated carbon-SBR (GAC-SBR) systems

Living bio-sludge from domestic wastewater treatment plant was used as adsorbent of heavy metals (Pb(2+), Ni(2+)) and its adsorption capacity was about 10-30% reduced by autoclaving at 110 degrees C for 10 min. The living bio-sludge acclimatized in synthetic industrial estate wastewater (SIEWW) without heavy metals showed the highest Pb(2+) and Ni(2+) adsorption capacities at 840+/-20 and 720+/-10 mg/g bio-sludge, respectively. The adsorbed Pb(2+) and Ni(2+) were easily eluted (70-77%) from bio-sludge by washing with 0.1 mol/l HNO(3) solution. The heavy metals (Pb(2+), Ni(2+)) removal efficiency of both SBR and GAC-SBR systems were increased with the increase of hydraulic retention time (HRT), or the decrease of organic loading. The SBR system showed higher heavy metals removal efficiency than GAC-SBR system at the same organic loading or HRT. The Pb(2+), Ni(2+), BOD(5), COD and TKN removal efficiencies of GAC-SBR system were 88.6+/-0.9%, 94.6+/-0.1%, 91.3+/-1.0%, 81.9+/-1.0% and 62.9+/-0.5%, respectively with industrial estate wastewater (IEWW) with 410 mg/l glucose, 5 mg/l Pb(2+) and 5 mg/l Ni(2+) under organic loading of 1.25 kg BOD(5)/m(3) d (HRT of 3 days). The bio-sludge quality (sludge volume index: SVI) of the system was less than 80 ml/g. The excess sludge from both SBR and GAC-SBR systems with SIEWW under the organic loading of 1.25-2.50 kg BOD(5)/m(3) d contained Pb(2+) and Ni(2+) at concentrations of 240-250 mg Pb(2+)/g bio-sludge and 180-210 mg Ni(2+)/g bio-sludge, respectively.     

Characterization of Pb<Superscript>2+</Superscript> biosorption from aqueous solution by<Emphasis Type="Italic"> Rhodotorula glutinis</Emphasis>

The yeast Rhodotorula glutinis was examined for its ability to remove Pb(2+) from aqueous solution. Within 10 min of contact, Pb(2+) sorption reached nearly 80% of the total Pb(2+) sorption. The optimum initial pH value for removal of Pb(2+ )was 4.5-5.0. The percentage sorption increased steeply with the biomass concentration up to 2 g/l and thereafter remained more or less constant. Temperature in the range 15-45 degrees C did not show any significant difference in Pb(2+ )sorption by R. glutinis. The light metal ions such as Na(+), K(+), Ca(2+), and Mg(2+) did not significantly interfere with the binding. The Langmuir sorption model provided a good fit throughout the concentration range. The maximum Pb(2+ )sorption capacity q(max) and Langmuir constant b were 73.5 mg/g of biomass and 0.02 l/mg, respectively. The mechanism of Pb(2+) removal by R. glutinis involved biosorption by direct biosorptive interaction with the biomass through ion exchange and precipitation by phosphate released from the biomass.     

Antibody labeling with copper-67 using the bifunctional macrocycle 4-[(1,4,8,11-tetraazacyclotetradec-1-yl)methyl]benzoic acid.

The high kinetic stability of the Cu2+ complex of the chelator 4-[(1,4,8,11-tetraazacyclotetradec-1-yl)-methyl]benzoic acid was demonstrated at physiological pH as well as under acidic conditions. The chelating agent was conjugated to AB35, a monoclonal antibody directed against CEA, without a significant loss of immunoreactivity. The conjugate could, under optimal labeling conditions, be labeled with 67Cu in acetate buffer with a full occupancy of ligands within 20 min. This radiolabeled conjugate showed no transfer of radiocopper to serum proteins in human serum over 7 days. The biodistribution in tumor-bearing mice was measured and compared to that of iodinated AB35. Tumor uptake was high with 15 +/- 3% ID (injected dose)/g after 24 h and 32 +/- 7% ID/g after 96 h for the 67Cu-labeled antibody and 13 +/- 4% ID/g after 24 h and 14 +/- 2% ID/g after 96 h for the 125I-labeled antibody. Whereas radioactivity in normal organs decreased with time after 24 h, increased residence time was shown up to 4 days with the 67Cu-labeled AB35.     

Cysteamine can induce duodenal ulceration in rats without depletion of immunoreactive somatostatin.

Single subcutaneous administration of cysteamine (2-aminoethanethiol, CSH) produces duodenal ulceration in rats within 24 h. Depletion of circulating and tissue somatostatin (SOM), hypergastrinemia and gastric acid hypersecretion have all been postulated as the pathophysiological response to CSH leading to ulceration. The purpose of this study was to analyze the synthesis, storage and secretion of gastrin and SOM as well as structural changes in SOM peptide after CSH treatment. Injection of 300 mg/kg (s.c.) of CSH caused macroscopic duodenal ulcers in seven out of eight rats at 24 h. Hypergastrinemia was seen within 30 min (from 23 +/- 4 to 74 +/- 20 pmol/l), and persisted for 4 h. Antral gastrin content was elevated at 30 min (2539 +/- 114 pmol/g) when compared to saline controls (1589 +/- 101 pmol/g). Plasma SOM did not change over the 24 h but antral SOM increased at 30 min (from 120 +/- 3 to 230 +/- 23 pmol/g) and remained elevated at 2 h (374 +/- 48 pmol/g) and 4 h (357 +/- 37 pmol/g). Fundic and duodenal SOM followed a similar pattern. Antral SOM mRNA was also elevated over the first 4 h (3-fold increase, P less than 0.05). HPLC analysis of antral tissue extracts revealed the presence of additional molecular forms of SOM which, however, differed from the major products of in vitro reduction with either CSH or dithiothreitol. Thus, the in vivo effect of CSH on SOM cannot be solely explained by a reductive opening of the disulphide bond. These results suggest that duodenal ulceration in rats treated with CSH is not related in a simple fashion to depletion of immunoreactive SOM. Early induction of hypergastrinemia may be important in the onset of ulceration. The value of CSH as a SOM depleting tool in gastrointestinal tissue must remain in doubt.     

Dissociation between release and gene expression of gonadotropin alpha-subunit in gonadotropin-releasing hormone-stimulated alpha T3-1 cell line.

The alpha T3-1 cell line which was derived by targeted tumorigenesis in transgenic mice [Windle et al. (1990) Mol. Endocrinol. 4, 597-603] possesses high-affinity binding sites for GnRH analogs coupled to enhanced phosphoinositide turnover and phospholipase D activity. Incubation of alpha T3-1 cells with [D-Trp6]-GnRH analog (GnRH-A) resulted in a rapid increase in gonadotropin alpha-subunit mRNA levels which was detected already at 30 min of incubation (0.1 nM GnRH-A, 3-fold, p < 0.01). The effect diminished with time to reach basal levels at about 12 h of incubation, with a secondary rise in alpha mRNA levels between 12 and 24 h of incubation. Addition of the protein kinase C activator 12-O-tetradecanoylphorbol 13-acetate (TPA, 100 ng/mL) or the Ca2+ ionophore ionomycin (1 microM) to alpha T3-1 cells also resulted in a rapid increase in alpha-subunit mRNA levels. Surprisingly, GnRH-induced alpha-subunit release was detected only after a lag of 4 h of incubation. Thus, dissociation between exocytosis and gene expression can be demonstrated in GnRH-stimulated alpha T3-1 cell line.     

The influence of lead on callose formation in roots ofLemna minor L

The treatment ofLemna minor L. plants with Pb(NO₃)₂ for 90 min, 8 and 24 h resulted in intensified deposition of (l,3)-P-glucan (callose) in plants roots. It was localized in the protodermis of the root tip, and in the center of the stele in the region at the proximal part of the root cap and slightly above     

Cholera toxin-induced changes in force of contraction and cyclic AMP levels in canine ventricular myocardium: Inhibition by carbachol

Cholera toxin (1–10 μg/ml) had a biphasic inotropic action on the isolated canine ventricular muscle: it produced a transient negative and a long lasting positive inotropic effect. The negative effect reached a maximum 43 + 2 min (n = 12) after administration of the toxin, while it took 3–5 hrs for the positive effect to reach a steady level. The positive inotropic effect of cholera toxin was accompanied by a prominent abbreviation of the time to peak tension and the relaxation time of individual contractions. The level of adenosine 3′,5′-cyclic monophosphate (cyclic AMP) of the tissue was elevated by cholera toxin in a time- and concentration-dependent manner. Carbachol (1 μmol/l) administered 3 or 5 hrs after the administration of cholera toxin (10 μg/ml) reversed the increase in force of contraction and the elevation of cyclic AMP levels induced by cholera toxin. These results indicate that cholera toxin exerts a cyclic AMP-dependent positive inotropic effect and a negative inotropic effect which is not related to cyclic AMP levels in canine ventricular myocardium.     

Factors affecting immobilization of heavy metals by purple nonsulfur bacteria isolated from contaminated shrimp ponds

In order to remove heavy metals (HMs) from contaminated shrimp pond at the highest concentrations found of; 0.75 mg/l Cd²⁺, 62.63 mg/l Pb²⁺, 34.60 mg/l Cu²⁺ and 58.50 mg/l Zn²⁺, two strains of purple nonsulfur bacteria isolated from shrimp ponds (NW16 and KMS24) were investigated for their ability to immobilize HMs in 3% NaCl in both microaerobic-light and aerobic-dark conditions. Based on metabolic inhibition and metabolic-dependent studies, it was concluded that both strains removed HMs using biosorption and also bioaccumulation. The efficiency of removal by both strains with both incubating conditions tested was in the order of lead (Pb) > copper (Cu) > zinc (Zn) > cadmium (Cd). Optimal conditions for removal of HMs by strain NW16 were; cells in the log phase at 4.5 mg DCW/ml, pH 6.0, and 30°C for 30 min. With microaerobic-light conditions, the relative percent removal of HMs was: Pb, 83; Cu, 59; Zn, 39; Cd, 23 and slightly more with the aerobic-dark conditions (Pb, 90; Cu, 69; Zn, 46; Cd, 28). Cells in the log phase at 5.0 mg DCW/ml, pH 5.5, and 35°C for 45 min were optimal conditions for strain KMS24 and there were no significant differences for the removal percentages of HMs with either incubating conditions (averages: Pb, 96; Cu, 75; Zn, 46; Cd, 30). The presence of Ca²⁺ and Mg²⁺ significantly decreased the removal capacity of HMs for both strains.     

Permeability of barriers to albumin flux in lungs of sheep resuscitated from hemorrhagic shock

We assessed pulmonary endothelial and epithelial permeability and lung lymph flow in nine adult sheep under base-line conditions and after resuscitation from profound hemorrhagic shock. Animals were mechanically ventilated and maintained on 1% halothane anesthesia while aortic pressure was held at 40 Torr for 3 h. Systemic heparin was not used. After reinfusion of shed blood, sheep recovered from anesthesia and we measured lung lymph flow (QL), lymph-to-plasma concentration ratio for proteins, and time taken to reach half-equilibrium concentration of intravenous tracer albumin in lymph (t1/2). Twenty-four hours after bolus injection of radio-albumin we lavaged subsegments of the right upper lobe and determined fractional equilibration of the tracer in the alveolar luminal-lining layer. In each sheep we had measured these parameters 7 days earlier under base-line conditions. Animals were killed, and the lungs were used for gravimetric determination of extravascular lung water (gravimetric extravascular lung water-to-dry weight ratio) 24 h after resuscitation from shock. Pulmonary endothelial injury after resuscitation was evidenced by marked increase in QL, without fall in lymph-to-plasma ratio. Time taken to reach half-equilibrium concentration fell from 169 +/- 47 (SD) min in base-line studies to 53 +/- 33 min after shock. There was no evidence of lung epithelial injury. Gravimetric extravascular lung water-to-dry weight ratio was significantly increased in these animals killed 24 h after resuscitation (4.94 +/- 0.29) compared with values in our laboratory controls (4.13 +/- 0.09, mean +/- SD). These data demonstrate a loss of lung endothelial integrity in sheep after resuscitation from profound hemorrhagic shock.     

The differential regulation of aldosterone output in hamster adrenal by angiotensinII and adrenocorticotropin.

Aldosterone was isolated from hamster adrenal cells and was identified by high performance liquid chromatography and thermospray mass spectroscopy analysis. Basal outputs from adrenal cell suspensions were of the same order of magnitude, 8.4 ± 1.9 ng and 8.0 ± 0.7 ng/2 h/50,000 cells, for aldosterone and corticosteroid, respectively. The outputs of aldosterone and corticosteroid increased with K⁺ concentrations to reach maxima of 3.3- and 1.6-fold at 10 meq/l of K⁺. Angiotensin_II (A_II) produced dose-dependent increases in aldosterone and corticosteroid outputs with maxima of 3- and 4-fold, respectively. In contrast, ACTH induced relatively no changes in aldosterone output, whereas dose-dependent increases in corticosteroid output were found. In time study experiments, with 10⁻⁸ M A_II, aldosterone and corticosteroid outputs were maximally increased after 1 h (6-fold) and 3 h (1.8-fold), respectively. At 10⁻⁸ M, ACTH had a small stimulatory effect on aldosterone output after 6 h, whereas it provoked a gradual increase in corticosteroid output (up to 7-fold after 8 h of incubation). The effects of A_II and ACTH on adrenal cytochrome P-450_11β involved in the last steps of aldosterone formation were evaluated by c combined in vivo andin vitro experiments. The P-450_11β mRNA level was increased by a low sodium intake but not by a 24 h ACTH stimulus. These results taken together indicate that ACTH and A_II differentially regulate P-450_11β. It is postulated that these two regulatory peptides regulate the hamster adrenal steroidogenesis by different P-450 genes.     

Effect of oxygen enrichment aeration on penicillin G acylase production in high cell density culture of recombinant E. coli

A strain of E. coli 9633 harboring pGL-5 is employed to develop the process producing penicillin G acylase (PGA). Medium studies show that 0.8% glucose is a proper initial carbon source concentration in the start medium. Whereas, study of nitrogen sources in the production medium exhibits that 2% soybean meat hydrolysate and 0.5% casein hydrolysate give the best result in terms of cell concentration. High cell density culture is carried out through the application of oxygen enrichment aeration (OEA). With the treatment of OEA, the cell concentration and specific PGA activity raise to 2.1 and 1.4 times, respectively, as compared to those without OEA. In a 75 l fermentor, the cell concentration can reach 323 (g wet cell weight/l) with a specific PGA activity of 47 (IU/g w.w.) after 24?h under OEA treatment. This means that the PGA activity of the broth can reach 15 (IU/ml).     

Catecholamines and the abundance of blood cells in a fresh water tropical teleost (Colisa fasciatus) in relation to cold-shock.

Intraperitoneal injections of epinephrine (0.05 microng/g) elicited characteristic changes in the abundance of circulating leucocytes at selected time intervals (viz., 3, 15 and 27 min. and, later, at intervals of 48 minutes up to 363 min. and at 12 and 24 h) post-injection in Colisa. Leucocytosis was evident as 15, 27 and 75 min, and tendency towards leucocytosis was observed at 123 and 267 min.; at 3, 171, 219, 315 and 363 min. and at 12 and 24 h, the total leucocyte counts for the experimentals and controls were not significantly different. No such corresponding significant changes were observed in the abundance of circulating erythrocytes or thrombocytes. Leucocyte sequence elicited by epinephrine was also apparent in Colisa which had been exposed to a temperature of 2 degrees C for one minute. Pretreatment with phenoxybenzamine (3.0 mg/l aquarium water), an alpha-adrenergic antagonist, abolished the cold-shock leucocytic phases, except 27 min. leucocytosis which emerged unaffected. Exogenous norepinephrine (2 microng/g) and isoproterenol (0.1 microng/g) failed to elicit any significant change in the number of circulating leucocytes, erythrocytes, or thrombocytes. Clearly adrenergic mechanisms are involved in the cold-shock leucocyte stress sequence. The results suggest alpha-activating role of epinephrine during the leucocyte stress syndrome in Colisa and, apparently, epinephrine is leucocytic.     

Lead inhibition of enzyme synthesis in soil.

Addition of 2 mg of Pb2+/g of soil concident with or after amendment with starch or maltose resulted in 75 and 50% decreases in net synthesis of amylase and alpha-glucosidase, respectively. Invertase synthesis in sucrose-amended soil was transiently reduced after Pb2+ addition. Amylase activity was several times less sensitive to Pb2+ inhibition than was enzyme synthesis. In most cases, the rate of enzyme synthesis returned to control (Pb2+) values 24 to 48 h after the addition of Pb. The decrease in amylase synthesis was paralleled by a decrease in the number of Pb-sensitive, amylase-producing bacteria, whereas recovery of synthesis was associated with an increase in the number of amylase-producing bacteria. The degree of inhibition of enzyme synthesis was related to the quantity of Pb added and to the specific form of lead. PbSO4 decreased amylase synthesis at concentrations of 10.2 mg of Pb2+/g of soil or more, whereas PbO did not inhibit amylase synthesis at 13 mg of Pb2+/g of soil. Lead acetate, PbCl2, and PbS reduced amylase synthesis at total Pb2+ concentrations of 0.45 mg of Pb2+/g of soil or higher. The results indicated that lead is a potent but somewhat selective inhibitor of enzyme synthesis in soil, and that highly insoluble lead compounds, such as PbS, may be potent modifiers of soil biological activity.     

耐铅镉菌株的分离鉴定及其吸附能力

堆肥中添加生物钝化剂是当前降低粪便中重金属生物毒性最为有效的方式之一,为了进一步提高其钝化重金属的能力,文中获得了复合重金属高耐性的钝化剂菌株,并探究其生物学特性和吸附特征。采集猪粪堆肥样品并在改良的牛肉膏培养基中分离和筛选耐铅又耐镉的高耐性菌株,通过形态结合分子生物学鉴定该菌株。该菌株分别在不同pH、温度和盐浓度条件下培养获得其最适的生长条件,进而在该条件下分析其对铅镉吸附的特性。结果获得一株耐铅浓度为600 mg/L、镉浓度为120 mg/L的铅镉复合耐性菌株SC19,该菌株为西地西菌属,其最适生长环境为pH值7.0、温度37℃、盐浓度0.5%。培养36 h的稳定期SC19菌株在吸附时间30min时铅的去除率最高,对铅的最大去除率和吸附量分别为60.7%和329.13mg/g;培养8h的对数期在吸附时间30min时镉的去除率最高,对镉的最大去除率和吸附量分别为51.0%和126.19 mg/g。红外光谱分析显示,SC19菌株对铅镉离子的吸附主要是细胞表面的多种活性基团与金属离子发生络合作用。该研究揭示了SC19菌株有较好的二价态铅镉离子吸附能力,可为生物钝化重金属提供重要的微生物种质资源。     

The plasma membrane-associated NADH oxidase of spinach leaves responds to blue light

The plasma membrane-associated NADH oxidase (NOX) of spinach leaf disks is characterized by oscillations in activity with a regular period length of ca. 24 min. Within a single population of plants exposed to light at the same time, NOX activities of all plants function synchronously. Exposure of plants transferred from darkness to blue light (495 nm, 2 min, 50 micromoles m-2 s-1) resulted in a complex response pattern but with a new maximum in the rate of NOX activity 36 (24+12) min after illumination and then with maxima in the rate of NOX activity every 24 min thereafter. Transient maxima in NOX activity were observed as well after 9.3 + /- 1.4 and 20.7 +/- 2.1 min. The blue light response differed from the response to red (650 nm, 10 min, 50 micromoles m-2 s-1) or white light where activity maxima were initiated 12 min after the light exposure followed by maxima every 24 min thereafter. Green or yellow light was ineffective. The light response was independent of the time in the 24-min NOX cycle when the light was given. The net effects of blue and red light were ultimately the same with a new maximum in the rate of NOX activity at 12+24=36 min (and every 24 min thereafter), but the mechanisms appear to be distinct.