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 role of Epstein-Barr virus (EBV) early antigen diffuse component (EA-D) and its relationship with EBV DNA polymerase in EBV genome-carrying cells are unclear, EBV-specified DNA polymerase was purified in a sequential manner from Raji cells treated with phorbol-12,13-dibutyrate and n-butyrate by phosphocellulose, DEAE-cellulose, double-stranded DNA-cellulose, and blue Sepharose column chromatography. Four polypeptides with molecular masses of 110,000, 100,000, 55,000, and 49,000 daltons were found to be associated with EBV-specified DNA polymerase activity. A monoclonal antibody which could neutralize the EBV DNA polymerase activity was prepared and found to recognize 55,000- and 49,000-dalton polypeptides. An EA-D monoclonal antibody, R3 (G. R. Pearson, V. Vorman, B. Chase, T. Sculley, M. Hummel, and E. Kieff, J. Virol. 47:183-201, 1983), was also able to recognize these same two polypeptides associated with EBV DNA polymerase activity. It was concluded that EBV EA-D polypeptides, as identified by R3 monoclonal antibody, are critical components of EBV DNA polymerase. 相似文献
Before 1985 some 54 Ordovician agnostidspecies and subspecies had been described fromChina.They were assigned to the following ele-ven genera and subgenera:Geragnostus,Trinodus,Pseudagnostus,Corrugatagnostus,Pseudoperonop-sis,Girvanagnostus,Geragnostella,Peziziopsis,Sphaeragnostus,Leiagnostus and Micragnostus.Most of them were based on inadequate materialand the range of morphological variation in theseforms largely unknown.After comparison,thepresent author tentatively retain 43 of the 54 spe-cies pendingfu rther material becoming available.They are now reassigned to the following ninegenera:Geragnostus,Arthrorhachis,Corrugatag- 相似文献
Much interest has currently been attached to the length distribution of microtubules polymerized in vitro and the related question of their possible 'dynamic instability'. Fundamental to this question is the mechanism of microtubule nucleation, which controls the rates of assembly and disassembly of microtubule protein in vitro. These kinetics are affected by a number of factors, including both the guanine nucleotides, GTP and GDP, and magnesium ion. Mg2+ exerts complex effects, as indicated by the existence of an optimal Mg2+ concentration for the maximum assembly rate of microtubule protein, and we investigate these effects in this report. At [Mg2+] greater than 0.5 mM, the characteristic lag-phase is substantially increased and the rate of assembly is greatly reduced without affecting the critical concentration significantly. We show that increasing [Mg2+] has two effects on the assembly process: nucleation is less efficient and the intrinsic rate constant for the elongation reaction is reduced. Lowering [Mg2+] (less than 0.5 mM) also inhibits nucleation. These effects of varying [Mg2+] can be explained predominantly in terms of enhanced stability of the microtubule-associated protein-containing oligomeric species present in the microtubule protein preparation. [Mg2+] is thus found to be a further important factor in microtubule nucleation, and hence, in determining length distributions in assembling microtubules. 相似文献
The organisation and expression of the rpl22, rps3, rpl16 and rpl14 genes, which belong to the S10- and spc-like operons of spinach chloroplasts, have been studied. Northern experiments and nuclease S1 mapping show that the two operon-like groups of genes are cotranscribed. It is demonstrated that the intron-containing rpl16 gene is spliced in vivo. Based on amino acid composition and protein sequence data, the products of the rpl22, rpl16 and rpl14 genes are identified respectively as the spinach chloroplast ribosomal proteins CS-L13, CS-L24 and CS-L29. The rpl22 gene product is a 5S rRNA binding protein and therefore is distinguishable from the homologous Escherichia coli L22 ribosomal protein. 相似文献
The cellular events accompanying neutrophil-mediated antibody-dependent cellular cytotoxicity (ADCC) directed against YAC erythroleukemic target cells have been studied by time-lapse fluorescence-intensified microscopy. The YAC plasma membrane and cytosol were labeled with the fluorescent probes diC18Icc and eosin Y, respectively. Fluorescently labeled and IgG-opsonized YAC cells were incubated at 37 degrees C while observed by optical microscopy. During temporal studies of neutrophil-YAC conjugates, the cytosol of YAC cells accumulated in tubular and spherical compartments of the neutrophils' vacuolar apparatuses. To distinguish between several possible mechanisms of target cytosol uptake, diC18Icc-labeled YAC cells were observed during identical conditions. The membrane label diC18Icc was found to accumulate within neutrophils in an identical fashion. At roughly 30 min, 25 and 38% of neutrophils in apparent conjugates had internalized tumor cell cytosol or plasma membrane, respectively, within a vesicular compartment. The IgG-dependent uptake of eosin Y and diC18Icc by neutrophils was diminished by exposure to 2.5 mM sodium azide. When cells were exposed to 5.5 mM sodium azide, 1 mM iodoacetamide, or 4 degrees C, conjugate formation and uptake of eosin Y or diC18Icc were abolished. An artifactual accumulation of eosin Y or diC18Icc in neutrophils was further ruled out by control studies. Non-specific exchanges of eosin Y and diC18Icc labels of YAC cells with tannic acid-treated red blood cells (RBCs) and normal neutrophils were studied. Since hemoglobin binds tightly to eosin Y, RBCs can easily detect eosin Y leakage. No exchange of eosin Y or diC18Icc from YAC cells into bound tannic acid-treated erythrocytes was found.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献