Ecotoxicity of soils contaminated with industrial and domestic wastewater in western shenyang,China

Soil samples were collected from 7 sites in the up-, mid-and down-reach along and nearby the wastewater irrigation channel, western Shenyang of China. The concentrations of selected pollutants (mineral oil, PAHs - polycycle aromatic hydrocarbons and Cd) were determined by UV spectrometer, HPLC and AAS (atomic adsorption spectrometer) spectrometer, respectively. Toxicity effects of soils were evaluated by seedling emergence test with root length of wheat as the end-point and by earthworms test with the mortality rate and inhibition rates of body weight as endpoints. Results showed accumulation of pollutants for most soils with concentration of 200.2 mg.kg⁻¹∼1600 mg.kg⁻¹ for mineral oil, 0.33 mg.kg⁻¹∼1.81 mg.kg⁻¹ for Cd and 900.16 mg.kg⁻¹ ∼ 2737.91 mg.kg⁻¹ for PAHs. The inhibition rates of root elongation were from −20% up to 40 %, and mortality rates of earthworms ranged from 0%∼40% from the exposure period of two weeks to eight weeks by sampling interval of two weeks, the inhibition rates of earthworm growth were from −19.36% to 34.53%, showing effects of stimulation at 2 weeks to an increasing effects of inhibition at 4, 6 and 8 weeks, respectively. Mortality rates correlated with the loss of body weight of earthworms.

This study indicated the potential risk of pollutants of environmental low content in soil by the determination of selected chemicals combined with toxicity indexes.

     

The distribution and kinetics of nuclei in rat osteoclasts

Osteoclast development and growth were studied by determining the number of labelled nuclei in osteoclasts of different sizes (based on the number of nuclei per osteoclast, N/O) and the number of osteoclasts with labelled nuclei at various intervals after tritiated thymidine [( 3H]TdR) injection in young rats. The osteoclast smears were made from the cellular periosteum of the proximal tibia. The frequency distribution of the N/O osteoclasts types in the smears had profiles similar to that of in situ osteoclasts in whole mounts of proximal tibia, which indicates that the osteoclast population of the smears was representative of that on the bone surface. A vast majority of the osteoclasts had a 1-6 N/O, and a number of the cells had as many as 26 or more nuclei. Furthermore, profiles of N/O frequency distributions were similar over the course of the study. Nuclei with [3H]TdR label were initially observed in osteoclasts between 4 and 12 hr after isotope injection. However, fusion of labelled nuclei to osteoclasts continued for at least 150 hr. In general, the labelled osteoclasts exhibited a significantly larger number of nuclei than the unlabelled osteoclasts. The probability of an osteoclast incorporating one or more labelled nuclei increased with time after injection and with an increase in N/O. Labelling intensity decreased with time post injection and with an increase in N/O. The data suggest that turnover of nuclei is more rapid in osteoclasts with high N/O values.     

Molecular cloning and expression in Escherichia coli of a cellodextrinase gene from Bacteroides succinogenes S85

A DNA fragment coding for a cellodextrinase of Bacteroides succinogenes S85 was isolated by screening of a pBR322 gene library in Escherichia coli HB101. Of 100,000 colonies screened on a complex medium with methylumbelliferyl-beta-D-cellobioside as the indicator substrate, two cellodextrinase-positive clones (CB1 and CB2) were isolated. The DNA inserts from the two recombinant plasmids were 7.7 kilobase pairs in size and had similar restriction maps. After subcloning from pCB2, a 2.5-kilobase-pair insert which coded for cellodextrinase activity was isolated. The enzyme was located in the cytoplasm of the E. coli host. It exhibited no activity on carboxymethyl cellulose, Avicel microcrystalline cellulose, acid-swollen cellulose, or cellobiose but hydrolyzed p-nitrophenyl-beta-D-cellobioside and p-nitrophenyl-beta-D-lactoside. The Km (0.1 mM) for the hydrolysis of p-nitrophenyl-cellobioside by the enzyme expressed in E. coli was similar to that reported for the purified enzyme from B. succinogenes. Expression of the cellodextrinase gene was subjected to catabolite repression by glucose and was not induced by cellobiose. The origin of the DNA insert from B. succinogenes was confirmed by Southern blot analysis. Western blotting (immunoblotting) using antibodies raised against the purified B. succinogenes cellodextrinase revealed a protein with a molecular weight of approximately 50,000 in E. coli clones which comigrated with the native enzyme isolated from B. succinogenes. These data indicate that the cellodextrinase gene expressed in E. coli is fully functional and codes for an enzyme with properties similar to those of the native enzyme.     

Identification and production of Δ9-cis-1, 18-octadecenedioic acid by Candida tropicalis

Summary The production of ⁹-cis-1, 18-octadecenedioic acid from different substrates by the mutant S₇₆ of Candida tropicalis was studied. It was found that the mutant could convert oleyl alcohol, oleic acid, and methyl oleate to ⁹-cis-1, 18-octadecenedioic acid through either the diterminal oxidation of the alcohol or the -oxidation of the terminal methyl group of the mono acid. The geometric configuration of the product was identified by different analytical methods. The results demonstrated that no change in the geometric configuration of molecular structure happened during the bioconversion of such unsaturated substrates to ⁹-dioic acid. To enhance the production of this dioic acid in the medium, calcium carbonate was added as a trapping agent. The IR spectrum, ¹H NMR and ¹³C-satellite spectra of this compound were presented.Dedicated to Professor Dr. K. Esser on the occasion of his 65th birthday     

鼎突多刺蚁群体结构和生活史的研究

本文报告了鼎突多刺蚁(Polyrhachis vicina Roger)的群体结构和生活史。通过研究表明,鼎突多刺蚁一年发生一代,以蚁后、雄蚁、工蚁、幼虫和卵越冬。卵和幼虫在冬天发育停滞(或极慢)。到了春天,随着气温的上升,卵和幼虫又恢复正常发育。据室内人工饲养观察,卵的发育历期为23.8±2.5天(平均温度26℃)幼虫为20.4±4.4天(26℃),工蚁蛹为19.8±5.5天(27℃)。成长工蚁在5—11月出现;8—11月,雄蚁从蛹中羽化;10月,雌蚁从蛹中羽化。雌蚁分飞交尾后,进入邻近蚁巢或回到原巢,脱翅成为蚁后。蚁巢内存在着多后现象。     

Conversion of apolipoprotein-specific high-density lipoprotein populations during incubation of human plasma

Incubation studies were performed on plasma obtained from subjects selected for relatively low levels of high-density lipoprotein cholesterol (HDL-C) (no greater than 30 mg/dl) and particle size distributions enriched in the HDL3 subclass. Incubation (12 h, 37 degrees C) of plasma in the presence or absence of lecithin: cholesterol acyltransferase activity produces marked alteration in size profiles of both major apolipoprotein-specific HDL3 populations (HDL3(AI w AII), HDL3 species containing both apolipoprotein A-I and apolipoprotein A-II, and HDL3(AI w/o AII), HDL3 species containing apolipoprotein A-I) as isolated by immunoaffinity chromatography. In the presence or absence of lecithin: cholesterol acyltransferase activity, plasma incubation results in a shift of HDL3(AI w AII) species (initial mean sizes of major components, approx. 8.8 and 8.0 nm) predominantly to larger particles (mean size, 9.8 nm). A less prominent shift to smaller particles (mean size, 7.8 nm) accompanies the conversion to larger particles only when the enzyme is active. Combined shifts to larger (mean size, 9.8 nm) and smaller (mean size, 7.4 nm) particles are observed for HDL3(AI w/o AII) particles (mean size, 8.3 nm) also only in the presence of enzyme activity. However, in the absence of enzyme activity, HDL3(AI w/o AII) species, unlike the HDL3(AI w AII) species, are converted to smaller (mean size 7.4 nm) rather than to larger particles. Like native HDL2b(AI w/o AII) particles, the larger HDL3(AI w/o AII) conversion products exhibit a protein moiety with molecular weight equivalent to four apolipoprotein A-I molecules per particle; small HDL3(AI w/o AII) products are comprised predominantly of particles with two apolipoprotein A-I per particle. Incubation-induced conversion of HDL3 particles in the presence of lecithin: cholesterol acyltransferase activity is associated with increased binding of both apolipoprotein-specific HDL populations to low-density lipoproteins (LDL). The present studies indicate that, in the absence of lecithin: cholesterol acyltransferase activity, the two HDL3 populations follow different conversion pathways, possibly due to apolipoprotein-specific activities of lipid transfer protein or conversion protein in plasma. Our studies also suggest that lecithin: cholesterol acyltransferase activity may play a role in the origins of large HDL2b(AI w/o AII) species in human plasma by participating in the conversion of HDL3(AI w/o AII) particles, initially with three apolipoprotein A-I, to larger particles with four apolipoprotein A-I per particle.     

Molecular cloning and expression in Escherichia coli of a cellodextrinase gene from Bacteroides succinogenes S85.

A DNA fragment coding for a cellodextrinase of Bacteroides succinogenes S85 was isolated by screening of a pBR322 gene library in Escherichia coli HB101. Of 100,000 colonies screened on a complex medium with methylumbelliferyl-beta-D-cellobioside as the indicator substrate, two cellodextrinase-positive clones (CB1 and CB2) were isolated. The DNA inserts from the two recombinant plasmids were 7.7 kilobase pairs in size and had similar restriction maps. After subcloning from pCB2, a 2.5-kilobase-pair insert which coded for cellodextrinase activity was isolated. The enzyme was located in the cytoplasm of the E. coli host. It exhibited no activity on carboxymethyl cellulose, Avicel microcrystalline cellulose, acid-swollen cellulose, or cellobiose but hydrolyzed p-nitrophenyl-beta-D-cellobioside and p-nitrophenyl-beta-D-lactoside. The Km (0.1 mM) for the hydrolysis of p-nitrophenyl-cellobioside by the enzyme expressed in E. coli was similar to that reported for the purified enzyme from B. succinogenes. Expression of the cellodextrinase gene was subjected to catabolite repression by glucose and was not induced by cellobiose. The origin of the DNA insert from B. succinogenes was confirmed by Southern blot analysis. Western blotting (immunoblotting) using antibodies raised against the purified B. succinogenes cellodextrinase revealed a protein with a molecular weight of approximately 50,000 in E. coli clones which comigrated with the native enzyme isolated from B. succinogenes. These data indicate that the cellodextrinase gene expressed in E. coli is fully functional and codes for an enzyme with properties similar to those of the native enzyme.     

Factors affecting adhesion of Fibrobacter succinogenes subsp. succinogenes S85 and adherence-defective mutants to cellulose.

Fibrobacter succinogenes subsp. succinogenes S85, formerly Bacteroides succinogenes, adheres to crystalline cellulose present in the culture medium. When the cells are suspended in buffer, adhesion is enhanced by increasing the ionic strength. Heat, glutaraldehyde, trypsin, and pronase treatments markedly reduce the extent of adhesion. Treatment with dextrinase, modification of amino and carboxyl groups with Formalin or other chemical agents, and inclusion of either albumin (1%) or Tween 80 (0.5%) do not decrease the degree of adhesion. Adherence-defective mutants isolated by their inability to bind to cellulose exhibited different growth characteristics. Class 1 mutants grew on glucose, cellobiose, amorphous cellulose, and crystalline cellulose. Class 3 mutants grew on glucose and cellobiose but not on amorphous or crystalline cellulose. No substantial changes were detected in the endoglucanase, cellobiosidase, and cellobiase activities of the wild type and the mutants. These data suggest that adhesion to crystalline cellulose is specific and that it involves surface proteins.