Metabolism of benzo[a]pyrene in cell suspension cultures of parsley (Petroselinum hortense,Hoffm.) and soybean (Glycine max L.)

Cell suspension cultures of parsley and soybean were incubated for 38 h with ¹⁴C-labeled benzo[a]pyrene; autoclaved cultures were used as controls. Metabolites were isolated by a sequential extraction procedure and further studied by chromatography or by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate. The soluble metabolites amounted to 1–2.2% in the case of parsley cells, and 19–28% in the case of soybean cells. These metabolites varied in polarity, some being soluble in organic solvent or aqueous buffer while other metabolite fractions were soluble only in hot aqueous sodium dodecylsulphate. In addition, a significant amount of an insoluble metabolite fraction was isolated from the culture fluid as well as the cellular material of soybean suspension cultures.Abbreviations BP benzo[a]pyrene - SDS sodium dodecyl sulfate - TCA trichloroacetic acid     

Standardization of high-resolution flow cytometric DNA analysis by the simultaneous use of chicken and trout red blood cells as internal reference standards

Determination of nuclear DNA content by flow cytometry requires comparison with a reference standard. The use of external standards such as lymphocytes or granulocytes is time-consuming and inaccurate. Chicken red blood cells (CRBC) have a DNA content of 35% of the human diploid value and have been widely used as internal standard. The ratio calculated on the basis of the peak channel numbers of the standard and the sample and used to indicate the DNA content (DNA ratio) is, however, very sensitive to changes in the zero level adjustment of the flow cytometer. If two internal standards are used the DNA ratio becomes independent of the zero level. Rainbow trout red blood cells (TRBC) have a DNA content of 80% of human diploid cells. A mixture of CRBC and TRBC was prepared and stored in small aliquots at -80 degrees C. This mixture was added to the sample before staining. The day-to-day variation of the DNA ratio obtained by use of the two standards was smaller than that obtained by CRBC alone. The possibility of sex related differences in DNA content of CRBC and TRBC was examined. The results indicated that a new batch of standards should be tested against the old batch to avoid the introduction of a systematic error.     

Esr,a second locus in the house mouse controlling esterase-5

Electrophoretic variation characterized by the presence (ES-5B⁺) or absence (ES-5B^–) of esterase-5B in the plasma of the house mouse has been observed. It is suggested that the expression of esterase-5B is controlled by an autosomal locus, Esr, linked to Ldr-1 on chromosome 6, in addition to the presumptive structural locus Es-5, which is located on chromosome 8. A gene order of Lyt-3-Esr-Ldr-1 was determined by two crosses.Supported by the Deutsche Forschungsgemeinschaft (SFB 46).This is communication No. 33 of a research program devoted to the investigation of cellular distribution and genetics of nonspecific esterases.     

The effect of different iron compounds on transferrin receptor expression in term human cytotrophoblast cells

During pregnancy, the mother is faced with an increased food demand. A good example of this increased demand is iron (Fe). Fe is needed in all growing cells. During pregnancy, the Fe transport to the fetus increases enormously. This amount can easily induce an Fe deficiency in the mother. Fe suppletion is very important for her, but not for the Fe status of the fetus, which is protected against Fe toxicity as well as deficiency. The placenta seems to be autonomous in Fe uptake. Likely there is a regulation mechanism. The human placenta is hemomonochorial. The cell layer of the fetus in contact with the maternal blood is formed by syncytiotrophoblasts. Fe is transported to the placenta by transferrin. Transferrin binds to a transferrin receptor on the trophoblast membrane and is internalized via an endocytic pathway. During this cycle, Fe is released from transferrin and the transferrin-transferrin receptor complex is recycled to the membrane. Isolated trophoblast cells from term placentas form a syncytium in vitro, and transferrin receptors are expressed. Expression depends on the number of cells in culture, culture time, the amount of Fe available, and the Fe compound. By regulation of the number of transferrin receptors, trophoblasts are able to control their Fe uptake.     

FITC-labeled lectins and calcofluor white ST as probes for the investigation of the molecular architecture of cell surfaces. Studies on conjugatophycean species

Summary In a screening program with 7 FITC-labeled lectins as probes, ConA receptors were identified in all of the 28 members of theConjugatophyceae, being under investigation. In nearly all of them RCA₁₂₀ receptors, too, are expressed. In 3 species only, PNA receptors, and in 2 species UEA receptors have been detected. No binding of DBA, SBA, and WGA was observed. The receptors for ConA, RCA₁₂₀, and UEA were shown to be associated with different molecules. Each lectin exhibits a unique and specific binding pattern, both chemically, as well as with regard to the topographic distribution on cell surfaces. While ConA receptors predominantly are associated with constituents of the cell wall, RCA₁₂₀ receptors mostly form part of the surrounding mucilage; the same holds for UEA receptors. Besides a variability of topographic distribution and species-to-species variation, a cell-to-cell variation exists in many species, suggesting that the expression of a lectin receptor is due to the developmental state of the cell and/or depends on external stimuli. In conclusion, we may point out, that FITC-labeled lectins turned out to be extremely useful probes for the investigation of the molecular architecture of cell walls. Calcofluor white ST binding to fibrillar polysaccharides (most probably cellulose) was shown to be inhibited by external incrustations of the cell wall. One species does not show any reaction with calcofluor white ST at all.     

A method for subgrouping the S-type of CMS forms in maize

Summary Simple correlations were calculated between nine different cms sources (cms-S, -R, -ML, -L, -CA, -EK, -C, -Rb, -T) on the basis of the weighted restoring reactions of 41 inbred lines. The Principal Component Analysis was applied to a 9 × 9 matrix which clearly grouped cytoplasms according to their similarities. The Principal Component I included S, R, ML, L, CA and EK cytoplasms; the Principal Component II contained C and Rb cytoplasms while T-cytoplasms was placed in Principal Component III. This corresponds to the main groupings indicated in the literature (Beckett 1971). However, after varimax rotation of the Principal Components, the S main group, including the 6 tested cytoplasms, fell into 3 subgroups: I.: S, R, ML; II.: L, CA; III.: EK.These data indicate that the Principal Component Analysis can be used to select a limited number of cms sources from the S group, representing the variability of the cytoplasmic gene pool of that group.     

Esterase-16 (Es-16): Characterization,polymorphism, and linkage to chromosome 3 of a kidney esterase locus of the house mouse

A polymorphism for an isozyme of a presumed arylesterase, esterase-16 (EC 3.1.1.2), has been detected in kidney, heart, and spleen of the house mouse, Mus musculus, by means of isoelectric focusing and by disc electrophoresis. Three phenotypes can be distinguished: the ES-16A phenotype (IEP 5.9) was found in C57BL/10Sn and many other laboratory inbred strains; the ES-16B phenotype (IEP 6.1) was found in M. m. molossinus; and the ES-16C phenotype (IEP 5.9; very weak activity) was found in Peru-Coppock. Esterase-16 is strongly inhibited by 10^?3 m p-chloromercuribenzoate, but not by 2·10^?4 m bis-p-nitrophenyl phosphate or by 10^?3 m Diamox. It stains well with indoxyl acetate and other indigogenic substrates but only weakly with α-naphthyl acetate. Esterase-16 is completely insoluble in water. It is apparently governed by a structural gene locus, Es-16, with three alleles, Es-16 ^a , Es-16^b, and Es-16 ^c, respectively. Es-16 is closely linked to Car-1 and Car-2 on chromosome 3. Typing of 94 animals of the backcross (C57BL/10Sn × M. m. mol.) F₁ × M. m. mol. revealed a recombination frequency of 8.51±2.9%.     

Spore ultrastructure in Sporothrix schenckii

Pathogenic strains of Sporothrix schenkii may show triangular spores, whose angular shape is maintained by a tiebeam effect in the inner cell wall structure. This difference in wall structure lies adjacent to a folded and possibly more active part of the spore cytoplasm. The supposed generation of asci in old cultures was simulated by the death of hyphae which are reinvaded by intrahyphal growth with intrahyphal spore production, while true asci were not seen.