The Effect of Chelating Agents on Soil Sodicity

Results of laboratory and field tests suggest that chelating agents could be used to alleviate adverse soil properties caused by excess sodium, such as low permeability. Adding multi-dentate carboxylic acid chelating agents to sodic soil, or to mixtures of soil with sodium-contaminated waste, significantly reduced sodium adsorption ratio (SAR) values. Judging from cation concentrations in saturated paste (sat. paste) filtrates, chelating agents act to ameliorate soil sodicity by releasing Ca and to a lesser extent Mg from undissolved compounds. After adding chelating agents to moist soils that contained free lime, measured weight losses were consistent with CO ₂ evolution due to CaCO ₃ decomposition. The electrical conductivity (EC) of the sat. paste filtrate of materials treated with chelating agents increased less than when equivalent Ca or Mg was supplied in conventional, soluble form. Bigger sat. paste vacuum filtration volumes, improved soil permeability and faster field infiltration rates were observed after treatment with chelating agents. The Ca- and Mg-complexes of agents such as citric and malic acid degrade in moist soil; such agents could perhaps be used in a series of applications to improve ease of cultivation and permeability of cropped land. The agent ethylenediamine tetraacetic acid (EDTA) forms stable complexes, and could therefore be used as a one-time treatment for sodic materials that are to be disposed of by burial, following guidelines for soil SAR and EC.     

The Mobilization of Copper in Sheep by Chelating Agents

D-penicillamine and 2,3-dimercapto-propane-l-sulphonate (DMPS) were administered orally and disodium-calcium-ethylene-diamine-tetraacetate (Ca-EDTA) subcutaneously into copper loaded sheep. The results showed that D-penicillamine has a copper mobilizing effect, while DMPS and Ca-EDTA do not seem to have this effect to any significant degree. Penicillamine, 52 mg/kg of body weight daily for 6 days, increased the urinary excretion of copper by a factor of 10 to 20. The same dosage (on weight basis) of DMPS increased the excretion of copper in urine by 2 fold. Following Ca-EDTA treatment no increase in urinary excretion of copper was observed. Penicillamine could be used in prophylactic treatment of copper toxicosis in sheep, but it is still too expensive for practical use.     

Analysis of the Chromosome Aberrations Induced by X-Rays in Somatic Cells of DROSOPHILA MELANOGASTER

A technique has been perfected for enabling good microscope preparations to be obtained from the larval ganglia of Drosophila melanogaster. This system was then tested with X-rays and an extensive series of data was obtained on the chromosome aberrations induced in the various stages of the cell cycle.-The analysis of the results obtained offers the following points of interest: (1) There exists a difference in radio-sensitivity between the two sexes. The females constantly display a greater frequency of both chromosome and chromatid aberrations. They also display a greater frequency of spontaneous aberrations. (2) In both sexes the overall chromosome damage is greater in cells irradiated in stages G(2) and G(1). These two peaks of greater radiosensitivity are produced by a high frequency of terminal deletions and chromatid exchanges and by a high frequency of dicentrics, respectively. (3) The aberrations are not distributed at random among the various chromosomes. On the average, the Y chromosome is found to be more resistant and the breaks are preferentially localized in the pericentromeric heterochromatin of the X chromosome and of the autosomes. (4) Somatic pairing influences the frequency and type of the chromosome aberrations induced. In this system, such an arrangement of the chromosomes results in a high frequency of exchanges and dicentrics between homologous chromosomes and a low frequency of scorable translocations. Moreover, somatic pairing, probably by preventing the formation of looped regions in the interphase chromosomes, results in the almost total absence of intrachanges at both chromosome and chromatid level.     

新制癌菌素和平阳霉素诱发蚕豆染色体畸变的比较研究

本文报道了新制癌菌素(NCS)能诱发植物染色体畸变,同时观察了利用咖啡因后处理对NCS、PYM诱发染色体畸变的影响,研究了PYM切断DNA断头的性质。结果表明,NCS切割DNA产生3'-羟基末端和3'-磷酸末端;咖啡因能封闭3'-羟基末端抑制DNA的修复,从而提高诱变频率。PYM加咖啡因后处理,其染色体畸变频率与PYM单独处理无明显差异。说明PYM切断DNA所得到的产物,不是3'-羟基末端,而是3'-磷酸末端。     

一种宫内节育器的染色体畸变试验研究

目的检测一种宫内节育器的体外细胞的染色体畸变作为遗传毒性评价的一部分。方法在加和不加S9活化系统条件下,试验组用三种不同浓度的节育器浸提液处理CHL细胞20h,对照组分别加入阴性、阳性进行交换,各组置37℃培养箱中培养。24h后采集细胞并分析中期细胞染色体畸变情况,计算染色体畸变率。结果在4g/20mL的浓度下受试物对细胞有明显的细胞毒性,其稀释浸提液的畸变率与阴性对照相比,在统计学上无显著性差异(P>0.05)。结论在该试验条件下,受试物稀释浸提液未诱发CHL细胞染色体畸变。     

The Effect of pH on the Action of Respiratory Inhibitors in Avena fatua Seeds

The effects of pH on the action of sodium azide, a cytochome-oxidaseinhibitor, and salicylhydroxamate (SHAM), an alternative respirationinhibitor, on the respiration of dormant seeds of wild oat (Avenafatua L.; line AN-51) were studied. While pH had little effecton seed respiration in controls, it strongly affected the activityof azide. One mM azide inhibited seed respiration at pH5, butstimulated it at pH 7. SHAM (10 mM) completely inhibited thestimulation of respiration by 1 mM azide in an unbuffered medium,but failed to do so when the medium was buffered at pH 7. Inunbuffered medium, 10 mM SHAM actually augmented the stimulationof respiration by 0.25 mM azide to the same degree as when theazide solution was acidified to mimic the pH change incurredwith dissolution of 10 mM SHAM. These results suggest that theinhibitory effect of SHAM on the action of azide in an unbufferedsystem may in part be due to its acidification of the incubationmedium rather than by the inhibition of alternative oxidase.Lower pH favours the formation of the undissociated hydrazoatemolecules causing greater inhibition of cytochrome-oxidase andother azide-sensitive enzymes. Avena fatua L, wild oat, seed dormancy, azide, salicylhydroxamate     

Effect of Respiratory Inhibitors on the Motility of Pseudomonas fluorescens

The translational motility of Pseudomonas fluorescens was weakly inhibited by oligomycin, Dicumarol, 2,4-dinitrophenol, 2n-heptyl-4-hydroxyquinoline N-oxide, and potassium cyanide. Atabrine and antimycin A together with potassium cyanide immediately immobilized this bacterium, but antimycin A alone was without effect. Gramicidin D also immobilized P. fluorescens, but its action was inhibited by K(+) and NH(4) (+) ions. In like manner, the effect of p-chloromercuribenzoate could be counteracted with cysteine, thereby suggesting the involvement of -SH groups in flagellar motility processes. It appears that the energy required for motility of P. fluorescens is generated by oxidative phosphorylation mediated by the cytochrome system.     

Effect of pH on the Activity of Some Respiratory Inhibitors

Inhibition of respiration of cultured cells of Petunia hybrida by NaF, NaN₃, malonic acid, and salicylhydroxamic acid increased at low pH. This increase could be partially reversed by raising the pH of the medium. Uptake experiments show that the greater inhibition of malonic acid at low pH was not the result of greater uptake. The results suggest that the increase in inhibition at low pH could not be attributed to greater cell penetration.     

Effect of Chelating Agents and Metal Ions on Gametangial Formation in the Moss Bryum argenteum Hedw

Chelating agents such as EDTA and EDDHA markedly stimulate theformation of gametangia in the dioecious moss Bryum argenteum,and the effect is more pronounced on male than on female clones.EDTA-stimulated gametangial formation is associated with significantincreases in endogenous iron and copper. Ferric citrate alsoenhances gametangial formation, but copper sulphate is inhibitory.The present findings are discussed in the context of earlierinvestigations on other plants in an attempt to explain thepossible involvement of chelating agents and metal ions in stimulatingthe onset of the reproductive phase in this moss. Bryum argenteum, gametangial formation, chelating agents, metal ions     

On the Power of Additional and Complex Chromosomal Aberrations in CML

Unregulated proliferation of mainly myeloid bone marrow cells and genetic changes in the hematopoietic stem cell system are important features in Chronic Myeloid Leukemia (CML). In clinical diagnosis of CML, classical banding techniques, fluorescence in situ hybridization (FISH) probing for the Philadelphia chromosome (Ph) or polymerase chain reaction amplifying the fusion products of the BCR-ABL fusion are state of the art techniques. Nevertheless, the genome of CML patients harbors many more cytogenetic changes. These might be hidden in subpopulations due to clonal events or involved in extremely complex aberrations. To identify these additional changes, several cytogenetic and molecular genetic techniques could be applied. Nevertheless, it has been proposed that identifying these aberrations is time consuming and costly and since they cannot be converted into a benefit for the patients, the necessity to perform these investigations has been questioned. In the times where highly specialized medicine is advancing into several areas of cancer, this attitude needs to be reassessed. Therefore, we looked at the usefulness of a combination of different techniques to unravel the genetic changes in CML patients and to identify new chromosomal aberrations, which potentially can be correlated to different stages of the disease and the strength of therapy resistance. We are convinced that the combination of these techniques could be extremely useful in unraveling even the most complex karyotypes and in dissecting different clones contributing to the disease. We propose that by doing so, this would improve CML diagnostic and prognostic findings, especially with regard to CML resistance mechanisms and new therapeutic strategies.     

激光及γ射线对有丝分裂染色体畸变感应现象的比较

波长514nm的激光照射可用于研究激光导致有丝分裂染色体畸变的效应。本文提供了一种新的辐照系统,能用于研究突变的感应现象,并与从γ-线辐射源获得的结果进行了比较。 Abstract:Laser irradiation at wavelength 514 nm was used to study the effect of lasers in inducing chromosomal aberrations at mitosis.This study offers a new radiation system which could be used for the induction of mutations.Results are compared with those obtained from studies using γ-rays as irradiation source.