Freezing of tissue-limits for the autoradiographic localization of diffusible substances

Frozen thin sections and sections from freeze-dried and embedded tissue are used for the autoradiographic localization of diffusible substances at the electron microscope level. The presence of ice crystals in such sections may limit the autoradiographic resolution. Ice crystals are formed during freezing and may grow during subsequent processing of tissue. The contribution of ice crystal growth to the final image was estimated by measuring the distribution of the ice crystal sizes in freeze-etch replicas and in sections from freeze-dried and embedded tissues. A surface layer (10-15 mu) without visible ice crystals was present in both preparations. Beneath this surface layer the diameter of ice crystals increased towards the interior with the same relationship between crystal size and distance from the surface in the freeze-etch preparation as in the freeze-dry preparation. Ice crystal growth occurring during a much longer time during freeze-drying compared to freeze-etching does not significantly contribute to the final image in the electron microscope. The formation of ice crystals during freezing determines to a large extent the image (and therefore the autoradiographic resolution) of freeze-dry preparations and this probably holds also for thin cryosections of which examples are given.     

Intensification of phenol biodegradation by humic substances

Phenol biodegradation was carried out in a batch system by the bacterial strain Cupriavidus metallidurans in the presence of potassium humate that was prepared by alkaline extraction from oxyhumolite. The experiments were focused on the assessment of the humate effect on biodegradation activity of the tested bacterial strain. The achieved results demonstrated that the humate has a positive influence on the biodegradation of phenol and reduces the incubation time necessary for phenol removal. Higher biodegradation rate and more intensive growth were observed during the cultivation in presence of humate in comparison to the cultivation without its addition. Adsorption of the humate on bacterial biomass was observed as well. Subsequently, a phenol biodegradation testing in a continuous-flow system using a biofilm reactor was also carried out. Although the reactor was inoculated by C. metallidurans only, the microbial composition under an aerobic non-aseptic condition during this long-term cultivation changed. The phenol removal efficiency obtained in the biofilm reactor was higher than 92% when phenol concentration in a treated medium was 1200 mg l⁻¹.     

Fixation and imaging of biological elements: heavy metals, diffusible substances, ions, peptides, and lipids

We tested various fixation and analysis methods to demonstrate by electron microscopy elemental imaging in tissues and cells, i.e., soluble substances such as many kinds of ionic elements, water soluble low molecular peptides, and even organic solvent soluble substances such as lipids. For the ionic elements, we tested frozen dried or freeze-substituted methods and organic or inorganic special chemical precipitation methods combined with microwaved fixation methods. The data were analyzed with electron beam X-ray microanalysis, electron energy filtered imaging analysis, and electron microscope autoradiography. The data were demonstrated as elemental distribution images and were calculated quantitatively. For the soluble low molecular peptides, we developed a tannic acid and aldehyde method combined with microwaved fixation. We discuss the theoretical background of the tannic acid fixation and microwaved fixation methods. For the organic solvent soluble substances, i.e., lipids including steroids, we successfully tested the use of a mixed fixative of aldehyde and osmium, digitonization, and osmification with the use of p-phenylendiamine or imidazole. We also proposed some new ideal biotracers for electron beam X-ray microanalysis and electron energy filtered imaging analysis.     

石油烃和酚类物质在土中的生物降解与土壤酶活性

本文通过模拟实验,研究了不同条件下石油烃和酚类物质在土中的降解进程及其与土壤酶活性的关系,并在此基础上,对所述污染物的土地处理提出了若干建议。     

Detection of proteins and phenol in DNA samples with second-derivative absorption spectroscopy.

We have employed near-uv second-derivative spectra of DNA, N-acetyl-L-tryptophanamide, N-acetyl-L-tyrosinamide, N-acetyl-L-phenylalanine ethyl ester, and phenol in a matrix least-squares multicomponent analysis algorithm to detect the presence of tryptophan, tyrosine, phenylalanine, and/or phenol in DNA preparations. With this method, each of these compounds can be detected in a DNA sample (absorbance, 0.1) at absorbance levels of less than 0.002. In practice, the presence of proteins can be detected at absorbance levels of less than 0.003. Using second-derivative spectra of proteins, contents of mixtures of proteins and DNA can be determined with less than 1% error. Mixtures of DNA and RNA can also be quantitatively analyzed with an error of approximately 2%. This technique can be easily implemented with computer-controlled spectrophotometers equipped with standard spectral analysis software. With prerecorded standard spectra, the time of analysis does not exceed a few seconds.     

Effects of growth substances on the absorption and transport of iron plants

The effects of a number of growth substances on the absorption and translocation of iron were studied in bean plants. Gibberellic acid application to the trifoliate leaf enhanced absorption of Fe applied to the primary leaf. 2-Chloroethyltrimethylammonium chloride increased absorption by the primary leaf while 6-furfurylaminopurine (kinetin) increased the transport of Fe from the primary leaf to other parts. When the roots were pretreated with gibberellic acid, the absorption of Fe by the primary leaf and subsequent transport to the trifoliate leaves were increased. Triiodobenzoic acid reduced the absorption and transport of Fe.     

天麻矿物质吸收及其营养机理探讨

探讨了天麻吸收矿物质过程和天麻的营养机理。研究蜜环菌在天麻的金属元素、非金属元素吸收中起的作用, 阐明天麻的有机营养吸收过程。提出了天麻吸收非金属元素的两个途径,分析了天麻吸收金属元素的“泵”的作用机理。指出了天麻蜜环菌之间的游离氨基酸特别是天冬氨酸和谷氨酸的交流是天麻和蜜环菌生长发育的关键。     

Effect of sympathomimetic substances and analogues on tail absorption of frog larva

Similarly to the effect of T3, the tail absorption of frog larvae (Rana arvalis) was stimulated in vitro by the sympathomimetic agents adrenaline, isoproterenol, ephedrine and the adrenaline analogue MMT. The effect of T3 administration was not inhibited by adrenaline, isoproterenol and MMT, but it was by ephedrine and T3 pretreatment. The adrenaline and isoproterenol effect manifested itself after early administration, but not after late and while ephedrine and MMT were effective at long-term administration, even it administered at a later time. Our experiments draw attention to the metamorphotic effect of substances capable of binding to beta-receptors. Their effect may be explained partly by the increase in the cAMP level, partly by a relationship existing between the beta-receptor and the T3 receptor.     

Determination of heavy elements in organic substances by X-ray absorption

Selective X-ray absorption method has been worked out to determine concentration of heavy elements in organic substances. The method is applicableOn leave from: Biological Research Center, Institute of Biophysics, Odesszai krt 62, H-6701 Szeged, Hungary in vivo.     

Simultaneous measurement of optical rotation dispersion and absorption spectra for chiral substances

We present a new method based on optical null methods for simultaneously measuring the optical rotatory dispersion (ORD) and absorption spectra of chiral substances. The optical rotation angle at a specific wavelength can be obtained from the optical nulls of the Malus curves with and without the sample. We use the optical nulls of the two curves as benchmark points and the readings to the right of the benchmark points by a certain angular offset to eliminate the influence of the analyzer on the light intensity and obtain the absorbance of the chiral substance at a specific wavelength. The 4096 pixels of the line scan CCD can measure multiple wavelengths simultaneously so that continuous ORD and absorption spectra can be obtained. The experimental results show that the standard deviation of the specific optical rotation is 0.11 deg mL g⁻¹ dm⁻¹, the standard deviation of the maximum absorption wavelength is 0.45 nm, and that absorbance of the sample varies linearly with the concentration. This method is helpful for simplifying the experiment and has a profound influence on the analysis of the contents and molecular configurations of chiral substances in the future.     

Cellular adsorption and absorption of antimony (III) by Mycobacterium smegmatis

Adsorption studies of Sb (III) as the antimonyl (125Sb) tartrate complex using acidified, non-proliferative suspensions of Mycobacterium smegmatis show that the uptake of Sb by the biomass increases with the external concentration of antimony ([Sb]) and decreases, at given concentration, with increasing pH. Measurements of Sb uptake in the cells under growth conditions in liquid culture indicate that the cellular concentration factor of antimony is of the order of 10 when the concentration of antimony in the medium is 10 microM, i.e., close to the minimum inhibitory concentration.     

Gel filtration and absorption spectroscopic investigations on humic substances from organic fertilizers

Summary Three organic fertilizers: a farmyard manure (FYM), humified poplar barks (PBF) and spruce barks (SBF) were investigated by means of chemical analysis and by the study of humic substances extracted by 0.1M sodium pyrophosphate (pH=10.0). The organic carbon content and the C/N ratio were higher in SBF, probably as a consequence of the short fermentation period (5 months). Yields of organic substances removed by three consecutive extractions with Na₄P₂O₇ solution were in the order: PBF>FYM>SBF. Nominal molecular weight distribution of total extracts was studied using Sephadex G type gels; TRIS buffer (pH=9.0) was the eluant, since the use of water produced complex gel-solute interactions. It was shown that SBF had a higher content of small size particles than the other two products which exhibited quite similar elution curves. Slopes of log A(absorbance)vs log plots and ratio of absorbances at 465 and 665 nm (E₄/E₆) of fractions containing particle of lower size were the steepest and the highest, respectively.     

Cellular absorption of anthraquinones emodin and chrysophanol in human intestinal Caco-2 cells

The intestinal absorption characteristics of anthraquinones emodin and chrysophanol were observed by measuring the intracellular accumulation across Caco-2 cells by the reverse-phase high performance liquid chromatography. The intracellular accumulation of chrysophanol was much greater than that of emodin, the maximum absorption of emodin and chrysophanol being 414.02+/-15.28 and 105.56+/-11.57 nmol/l x mg x protein, respectively. The absorption of each anthraquinone was significantly lower at 4 degrees C than that of 37 degrees C. The effects of the transport inhibitors, verapamil, cyclosporine and phloridzin, on the intracellular accumulation were also examined. Verapamil and cyclosporine increased the absorption of emodin and chrysophanol, while phloridzin inhibited their absorption, all in a dose-dependent manner. These results suggest that the absorption characteristics of emodin and chrysophanol were closely related to their special structure with the hydroxy groups. It is also likely that a specific transport system mediated the intracellular accumulation of emodin and chrysophanol across the Caco-2 cells.