Restriction fragment length polymorphism at the HLA-C locus

We have used the HLA-C-specific DNA probe pC250 to investigate restriction fragment length polymorphism (RFLP) at the HLA-C locus. Genomic Southern blot hybridization included DNA prepared from a panel of homozygous typing cells representing serological specificities Cw1 to Cw8 and also from samples representing Cw blanks. Although many restriction nucleases failed to reveal any polymorphism, RFLPs were evident with Taq I, Pvu II, Bst XI, Nde 1, and Nci I in addition to the previously reported Eco RI. In the case of Bst XI, a unique RFLP defined a subset of serologically defined Cw blanks. Comparison of RFLP sizes with restriction fragment lengths obtained from the known HLA-Cw3 gene sequence permitted the localization of intragenic C locus RFLLs and the identification of a variable Taq I site in the second intron, a variable Nci I site near the end of the fourth exon, and a variable Pvu lI site in the fifth intron.     

Characterization of a class of small auxin-inducible soybean polyadenylated RNAs

Four new auxin-responsive RNAs from soybean (Glycine max (L.) Merr., var. Wayne) are described. The RNAs were identified by hybridization to three cDNA probes obtained from a library enriched for sequences which increase in abundance within 60 min after 2,4-D (2,4-dichlorophenoxyacetic acid) treatment. These RNAs appear to define a new class of small (i.e. approximately 550 nucleotides) RNAs that respond extremely rapidly to application of exogenous auxin. In excised elongating hypocotyl sections, an increase in the abundance of these RNAs can be detected 2 to 5 min after treatment with 50 M 2,4-D. This response is half maximal after 10 min and reaches steady state in 60 min. RNA blot analysis shows that these RNAs are expressed differentially in various parts of the seedling. The degree of inducibility by auxin is also organ-specific, with the elongating hypocotyl being the most responsive of the organs tested. The RNAs display identical response specificities with one exception. Accumulation of one RNA, designated 10A, is completely abolished by simultaneous addition of cycloheximide and 2,4-D. This RNA also displays a different 2,4-D dose response than other RNAs examined. These results suggest that more than one mechanism is involved in rapid modulation of gene expression by auxin.     

External factors involved in the regulation of an extracellular proteinase synthesis in Bacillus megaterium

Summary A mathematical model was formulated to describe the kinetics and stoichiometry of growth and proteinase production in Bacillus megaterium. Synthesis of the extracellular proteinase in a batch culture is repressed by amino acids. The specific rate of formation of the enzyme (r _E) can be described by the formula {ie373-1}, where k ₂ and k ₃ stand for the non-repressible and repressible part of enzyme synthesis respectively, k _{S 2} is a repression coefficient and S ₂ indicates the concentration of amono acids; the values of k ₂ and k _{S 2} depend on the composition of the mixture of amino acids. Even in a high concentration, a single amino acid is less effective than a mixture of amino acids. The dependence of the proteinase repression on the concentration of an external amino acid (leucine) follows the same course as its rate of incorporation into proteins, approaching saturation at concentrations higher than 50 M (half saturation approximately 10 M). However, the total uptake of leucine did not exhibit any saturation even at 500 M external concentration.Symbols X biomass concentration, g/l - E proteinase concentration, unit/l - t time, h - S ₁ concentration of glucose, g/l - S ₂ concentration of amino acids, g/l - specific growth rate, l/h - rE specific rate of enzyme production, unit/g/h - k ₁ growth kinetic constant, l/h - k ₂ product formation kinetic constant (for non-repressible part of enzyme synthesis), unit/g - k ₃ product formation kinetic constant (for repressible portion of enzyme synthesis), unit/g - k _{S 1} saturation constant, g/l - k _{S 2} repression coefficient for a certain amino acid or amino acids mixture, g/l     

Physiological activity of immobilized cells of Claviceps fusiformis during long-term semicontinuous cultivation

Summary The 550-day semicontinuous cultivation of Claviceps fusiformis immobilized in calcium alginate is documented. The vegetative mycelium from seed or from early-production submerged culture is the best choice for immobilization. No extracellular glucans are produced by immobilized cells. Immobilized spores give low yields of clavine alkaloids. Alginate concentrations in a range of 2%–4% do not influence yield and spectrum of alkaloids. The cytoplasm of the immobilized cells becomes condensed (after 3 days), polysaccharides disappear, and centres of lipid synthesis are formed in the cytoplasm. After 60 days the cells harbour a great number of lipid particles, mitochondria are diminishing and their cristae partly disappear, indicating a decreased respiration capacity. After 350–500 days the volume of most cells is increased many times and the cells are filled with large oval bodies of electrondense material. Chloramphenicol protects immobilized cultures against bacterial contamination.     

Antimicrobial effects of some mono- and bishydrazones

Antibacterial, antifungal and antiprotozoal effects of nine mono- and bishydrazones of glycolaldehyde, glyoxal, methoxyacetaldehyde and glutaraldehyde were studied using eight model organisms. It was found that bishydrazones are much more efficient antimicrobial agents than monohydrazones in the case of all model microorganisms.     

Expression of HLA-DR antigens on tumour cells does not contribute to skin reactivity to autologous cholesteryl hemisuccinate (CHS)-treated tumour cells in patients with metastatic melanoma

Summary Skin tests with autologous cholesteryl hemisuccinate (CHS)-treated and untreated cells were performed in ten metastatic melanoma patients. In the majority of cases evident reaction was noted with CHS-treated cells (9/10) while the reaction with untreated cells was mostly negative (7/10). Tumour cell suspensions used for skin tests were characterized for reactivity with monoclonal antibody TAL 1B5 detecting the HLA-DR alpha chain. There were no differences between CHS-treated and untreated cells with respect to HLA-DR expression and no correlation was found between grade of skin reaction to CHS-treated cells and the proportion of HLA-DR positive cells in the injected cell sample.     

Limiting factors for seed production in Cynoglossum officinale

Summary Over three years of study, small plants of Cynoglossum officinale consistently produced more flowers per unit of dry weight than large plants. In contrast to earlier results, weight of all seeds tended to increase more than proportional to size. As a result a positive correlation existed between seed set per flower and plant size. The correlation between the mean number of pollinator visits per flower and size was positive but not significant. In a field experiment we found that resources rather than pollen were limiting seed set. Thus, it is unlikely that enhanced pollination of the largest plants causes the size-dependency of seed set per flower. Alternative hypotheses are discussed briefly.Publication of the Meijendel Comité, New Series No. 96     

Phosphoribosyl pyrophosphate and the measurement on inorganic pyrophosphate in plant tissues

This work provides further evidence that plants contain appreciable amounts of inorganic pyrophosphate (PPi), and that breakdown of phosphoribosyl pyrophosphate (PPRibP) does not contribute significantly to the PPi detected in plant extracts. Inorganic pyrophosphate in extracts of the roots of Pisum sativum L., clubs of the spadices of Arum maculatum L., and the developing endosperm of Zea mays L. was assayed with pyrophosphate fructose 6-phosphate 1-phosphotransferase (EC 2.7.1.90), and with sulphate adenyltransferase (EC 2.7.7.4). The two different assays gave the same value for PPi content, and for recovery of added PPi. It was shown that PPRibP is converted to PPi during the extraction of PPi. However, the amounts of PPRibP in clubs of A. maculatum and the developing endosperm of Z. mays were negligible in comparison with the contents of PPi.Abbreviations EDTA ethylenediaminetetraacetic acid - PFK(PPi) pyrophosphate fructose 6-phosphate 1-phosphotransferase - PPi inorganic pyrophosphate - PPRibP phosphoribosyl pyrophosphate