Fasciola hepatica and Schistosoma mansoni: immunofluorescent antigen localization and cross-reactivity

In an attempt to identify the tissue sources of biochemically purified antigenic fractions of Fasciola hepatica and Schistosoma mansoni, antisera were tested against plastic-embedded sections of worms of various ages by an indirect fluorescent-antibody-labeling technique. Antibodies prepared against antigens purified by chromatography of F. hepatica whole worm extract through concanavalin A-Sepharose 4B labeled the parenchyma and tegument of adult F. hepatica strongly while antibodies developed against antigens purified by antibody-affinity chromatography against antibodies of S. mansoni labeled only the parenchyma. Antigens common to these two groups clearly originated from F. hepatica parenchyma. Certain of these common antigens are known to provide significant protection in mice to challenge with S. mansoni cercariae, and in the present study antisera against F. hepatica extracts cross-labeled S. mansoni adult male parenchyma. Reciprocal cross-reactions between antisera against S. mansoni and the parenchyma of adult F. hepatica were also noted. FhFIIb, an extract of F. hepatica which Tailliez described as not cross-reacting with S. mansoni, was found to contain no F. hepatica parenchymal antigens. Antigenic fractions of F. hepatica and S. mansoni collected from the surface of worms after incubation in nonionic detergent were unexpectedly found to contain much parenchymal antigen, suggesting leakage of internal components into the supernatant during preparation. Antisera to F. hepatica developed during a natural infection in rabbits labeled tegumental components and gut strongly but did not react with parenchymal tissue. Antisera against extracts of adult schistosomes labeled the parenchyma of male worms and the glycocalyx of the cercarial tegument, indicating the presence of common antigens in the adult and the cercarial stage. Reciprocal reactions between anticercarial sera and adult sections provided further evidence of shared antigenicity. Antisera against S. mansoni egg antigens strongly labeled sections of eggs in liver tissue and cross-reacted with cercarial glycocalyx, indicating the existence of common antigens between these two stages. The antisera also cross-reacted with what appeared to be non-membrane-bound protein in the tegument of F. hepatica. The soluble egg antigen extract shared antigenicity with the parenchyma of both S. mansoni and F. hepatica but circumoval precipitin had no cross-reactivity with this tissue. Thus S. mansoni eggs contain nondiffusable components sharing antigenic specificity with adult parenchymal tissue.(ABSTRACT TRUNCATED AT 400 WORDS)     

Effect of photosynthesis on dark mitochondrial respiration in green cells

Green plant cells can generate ATP in both chloroplasts and mitochondria. Hence the effect of photosynthesis on dark mitochondrial respiration can be considered at a variety of levels. Turnover of ceitric acid cycle dehydrogenases, which is essential for supply of carbon skeletons for amino acid synthesis, seems to be largely unaffected during photosynthesis. The source of carbon for the anaplerotic function of the citric acid cycle in light is however, not known with certainty. NADH generated in these reactions is probably not oxidised via the mitochondrial electron transfer chain coupled to ATP synthesis. However, it may be oxidised by the alternative cyanide-insensitive pathway, exported to the cytosol via the oxaloacetate-malate dicarboxylate shuttle or directly utilised for cytosolic nitrate reduction. Oxidation of succinate via cytochrome oxidase may also be similarly inhibited in light. Whether increase in the cytosolic ATP/ADP ratio in light is responsible for the inhibition of mitochondrial electron transfer to O₂ is not clearly established, because the ATP/ADP ratio is reported to be already quite high in the dark. Effective collaboration between photophosphorylation and oxidative phosphorylation in order to maintain the cytosolic energy charge at a present high level is discussed.     

Sedimentation properties of chitosomes fromMucor rouxii

Summary This study was undertaken to assess the distribution and localization of chitin synthetase in a fungal cell and to evaluate the sedimentation behavior of chitosomes (microvesicular containers of chitin synthetase). Chitosomes were isolated from cell-free extracts of yeast cells ofMucor rouxii by rate-zonal and isopycnic sedimentation in sucrose density gradients. Because of their small size and low density, chitosomes were effectively separated from other subcellular particles. Rate-zonal sedimentation was a suitable final step for isolating chitosomes as long as ribosomes had been eliminated by enzymic digestion. By isopycnic centrifugation, chitosomes could be separated directly from a crude cell-free extract; they cosedimented with a sharp symmetrical peak of chitin synthetase at a buoyant density of d=1.14–1.15g/cm³; the only significant contaminants were particles of fatty acid synthetase complex. From such sedimentations, we estimated that 80–85% of the chitin synthetase activity in the cell-free extract was associated with chitosomes; the rest was found in two smaller peaks sedimenting at d=1.19–1.20 and d=1.21–1.22 (5–10%), and in the cell wall fraction (5–10%). By consecutive rate-zonal and isopycnic sedimentations, chitosome preparations with relatively few contaminating particles were obtained. Potassium/sodium phosphate buffer (pH 6.5)+MgCl₂ was the most effective isolation medium for chitosomes. Other buffers such as TRIS-MES+MgCl₂ led to massive aggregation of chitosomes and a change in sedimentation properties. This tendency of chitosomes to aggregate could explain why most of the chitin synthetase activity of a fungus is sometimes found associated with other subcellular structures,e.g., plasma membrane.     

Molecular and cytological characteristics of nuclear DNA and chromatin for angiosperm systematics: DNA diversification in the evolution of four orchids

The species- and genus-specific DNA content, average base composition of nuclear DNA, presence or absence of satellite DNA, the percentage of heterochromatin and other characteristics of nuclear DNA and nuclear structure allow to deduce the molecular changes which accompanied, or more probably caused, cladogenesis in the orchids studied. It is suggested that saltatory replication (generative amplification) of certain DNA sequenes, diversification of reiterated DNA sequences, and loss of DNA play an important role in the evolution of orchids.—The relationship between changes of genome composition and of nuclear structure and ultrastructure is discussed on the basis of cot curves, heterochromatin staining with Giemsa (C banding), electron microscopy of nuclei, and molecular hybridization in situ.Some aspects of this paper have been presented at the Helsinki Chromosome Conference, August 1977 (Nagl & Capesius 1977).     

Genetics of the peroxidase isoenzymes in Petunia

Summary By starch gel electrophoresis three mobility variants of a cathodic moving doublet of bands, encoded by the structural gene prxC, were detected in all organs of flowering petunias. In root tissue two of the variants showed a lower electrophoretic mobility than in other organs. During development of flower buds the PRXc enzymes showed an increase in mobility. The gene prxC was located on chromosome IV by showing linkage to the genes An3 and Dw1, by trisomic segregation, and by the construction of triply heterozygous trisomics IV. The gene order on chromosome IV is B1-An3/Dw1-prxC. It was concluded that the temporal programming difference in the expression of the alleles prxC2 and prxC3 is caused by internal site mutation. Analysis of progeny obtained by crossing of lines to the trisomic IV with genotype prxC1/C1/C2 showed differential expression of the two prxC1 alleles of the trisomic IV.     

Ultrastructural localization of alkaline phosphatase in the cyanobacteriaCoccochloris peniocytis andAnabaena cylindrica

Summary Histochemical techniques applied at the ultrastructural level have established the periplasmic space as the site of cell bound alkaline phosphatase activity inAnabaena cylindrica andCoccochloris peniocytis. For localization of activity unfixed cells were reacted with calcium nitrate, which acts as the initial capture reagent. After this deposition, the cells were suspended in 2% lead nitrate to convert the calcium phosphate to more electron dense lead phosphate. The majority of cell bound activity appeared to be associated with layer 3 of the cell wall. InA. cylindrica a secondary site of cell bound activity appeared to be in the sheath. Placement in a phosphate free medium caused a substantial increase in the enzyme activity ofA. cylindrica while the activity present in log phase cells ofC. peniocytis was similar to that found in phosphate starved cells.C. peniocytis also secretes the enzyme into the surrounding medium.     

The distribution of hydroxycinnamic acid amides in flowering plants

Hydroxycinnamic acid amides have been identified as the main phenolic constituents in the reproductive organs of a range of flowering plants.     

Discrimination between12C and13C by marine plants

Summary The natural abundance¹³C/¹²C ratios (as δ¹³C) of organic matter of marine macroalgae from Fife and Angus (East Scotland) were measured for comparison with the species' ability to use CO₂ and HCO ₃ ^- for photosynthesis, as deduced from previously published pH-drift measurements. There was a clear difference in δ¹³C values for species able or unable to use HCO ₃ ^- . Six species of Chlorophyta, 12 species of Phaeophyta and 8 species of Rhodophyta that the pH-drift data suggested could use HCO ₃ ^- had δ¹³C values in the range -8.81‰ to -22.55‰. A further 6 species of Rhodophyta which the pH-drift data suggested could only use CO₂ had δ¹³C values in the range -29.90‰ to-34.51‰. One of these six species (Lomentaria articulata) is intertidal; the other five are subtidal and so have no access to atmospheric CO₂ to complicate the analysis. For these species, calculations based on the measured δ¹³C of the algae, the δ¹³C of CO₂ in seawater, and the known¹³C/¹²C discrimination of CO₂ diffusion and RUBISCO carboxylation suggest that only 15–21% of the limitation to photosynthesisin situ results from CO₂ diffusion from the bulk medium to the plastids; the remaining 79–85% is associated with carboxylation reactions (and, via feedback effects, down-stream processes). This analysis has been extended for one of these five species,Delesseria sanguinea, by incorporating data onin situ specific growth rates, respiratory rates measured in the laboratory, and applying Fick's law of diffusion to calculate a boundary layer thickness of 17–24 μm. This value is reasonable for aDelesseria sanguinea frondin situ. For HCO ₃ ^- -using marine macroalgae the range of δ¹³C values measured can be accommodated by a CO₂ efflux from algal cells which range from 0.306 of the gross HCO ₃ ^- influx forEnteromorpha intestinalis (δ¹³C=-8.81‰) in a rockpool to 0.787 forChondrus crispus (δ¹³C=-22.55‰). The relatively high computed CO₂ efflux for those HCO ₃ ^- -users with the more negative δ¹³C values implies a relatively high photon cost of C assimilation; the observed photon costs can be accommodated by assuming coupled, energy-independent inorganic carbon influx and efflux. The observed δ¹³C values are also interpreted in terms of water movement regimes and obtaining CO₂ from the atmosphere. Published δ¹³C values for freshwater macrophytes were compared with the ability of the species to use CO₂ and HCO ₃ ^- and again there was an apparent separation in δ¹³C values for these two groups. δ¹³C values obtained for marine macroalgae for which no pH-drift data are available permit predictions, as yet untested, as to whether they use predominantly CO₂ or HCO ₃ ^-     

Soil acidification as caused by the nitrogen uptake pattern of Scots pine (Pinus sylvestris)

Three-year-old Scots pine (Pinus sylvestris) trees were grown on a sandy forest soil in pots, with the objective to determine their NH₄/NO₃ uptake ratio and proton efflux. N was supplied in three NH₄-N/NO₃-N ratios, 3:1, 1:1 and 1:3, either as ¹⁵NH₄+¹⁴NO₃ or as ¹⁴NH₄+¹⁵NO₃. Total N and ¹⁵N acquisition of different plant parts were measured. Averaged over the whole tree, the NH₄/NO₃ uptake ratios throughout the growing season were found to be 4.2, 2.5, and 1.5 for the three application ratios, respectively. The excess cation-over-anion uptake value (C_a-A_a) appeared to be linearly related to the natural logarithm of the NH₄/NO₃ uptake ratio. Further, this uptake ratio was related to the NH₄/NO₃ ratio of the soil solution. From these relationship it was estimated that Scots pine exhibits an acidifying uptake pattern as long as the contribution of nitrate to the N nutrition is lower than 70%. Under field circumstances root uptake may cause soil acidification in the topsoil, containing the largest part of the root system, and soil alkalization in deeper soil layers.