Differential accumulation of hydroxyproline-rich glycoproteins in bean root nodule cells infected with a wild-type strain or a C4-dicarboxylic acid mutant of Rhizobium leguminosarum bv. phaseoli

An antiserum raised against deglycosylated hydroxyproline-rich glycoproteins (HPGPs) from melon (Cucumis melo L.) was used to study the relationship between Rhizobium infection and induction of HRGPs in bean (Phaseolus vulgaris L.) root nodule cells infected with either the wild-type or a C₄-dicarboxylic acid mutant strain of Rhizobium leguminosarum bv. phaseoli. In effective nodules, where fixation of atmospheric dinitrogen is taking place, HRGPs were found to accumulate mainly in the walls of infected cells and in peribacteroid membranes surrounding groups of bacteroids. Internal ramifications of the peribacteroid membrane were also enriched in HRGPs whereas the peribacteroid space as well as the bacteroids themselves were free of these glycoproteins. In mutant-induced root nodules, HRGPs were specifically associated with the electron-dense, laminated structures formed in plastids as a reaction to infection by this mutant. The presence of HRGPs was also detected in the host cytoplasm. The aberrant distribution of HRGPs in infected cells of mutant-induced nodules likely reflects one aspect of the altered host metabolism in relation to peribacteroid-membrane breakdown. The possibility that the antiserum used for HRGP localization may have cross-reacted with ENOD 2 gene products is discussed in relation to amino-acid sequences and sites of accumulation.     

Use of pectinases complexed to colloidal gold for the ultrastructural localization of polygalacturonic acids in the cell walls of the fungus Ascocalyx abietina

Summary Three pectinase—gold complexes were used to localize polygalacturonic acids in the fungusAscocalyx abietina (Lagerberg) Schlaepfer-Bernhard. With the pectinesterase and pectin lyase—gold complexes, the labelling was uniformly distributed over the fungus walls and did not seem to be significantly influenced by the tissue preparation. With the polygalacturonase—gold complex, differences in the labelling distribution were noted according to the fixation procedure indicating, therefore, that osmication of the tissues could greatly interfere with the localization of the specific enzyme binding sites. These results demonstrate, for the first time, the possibility of detecting polygalacturonic acids by means of different gold-complexed pectinases.     

Ultrastructural localization of glycoconjugates in the fungus Ascocalyx abietina, the Scleroderris canker agent of conifers, using lectin-gold complexes

Different glycoconjugates were revealed in the fungus Ascocalyx abietina (Lagerberg.) Schlaepfer-Bernhard, by using various lectin-gold complexes. N-acetylglucosamine, N-acetylgalactosamine, and D-mannose were specifically localized in cell walls of fungal cells. N-acetylneuraminic acid (sialic acid) and L-fucose were detected in structures corresponding to lipid bodies, whereas they were totally absent in the cell wall. This is the first report on the occurrence of sialic acid in fungi and of fucose in Ascomycetes. The great advantage of using lectin-gold complexes for ultrastructural localization of sugars in phytopathogenic fungi, as well as in studies concerning host-pathogen interactions, is discussed.     

On the compatibility of carbon uptake rates calculated from stable and radioactive isotope data: implications for the design of experimental protocols in aquatic primary productivity

Basic differences between the ¹³C and the ¹⁴C techniques ofmeasuring carbon uptake by phytoplankton exist at the levelof the isotopic analysis. With the first method, a ratio ofisotopic abundances is measured on the sample, whereas an absoluteamount of isotope is estimated with the second method. If acarbon source other than the labeled one is utilized by thephytoplankton during incubation, the stable isotope method maybe biased. Specific uptake values will be underestimated bythis effect. It is, however, possible to obtain unbiased estimatesof the ¹³C-labeled carbon uptake by using an equation containinga term describing the final particulate carbon concentration.Only under this condition will carbon uptake rates derived from¹³C isotope data be always compatible with the ¹³C method ofmeasuring primary production ^*This paper is the result of a study made at the Group for AquaticPrimary Productivity (GAP), Second International Workshop heldat the National Oceanographic Institute, Haifa, Israel in April–May1984.     

A proton-deuterium exchange study of three types ofDesulfovibrio hydrogenases

Summary Hydrogenases are among the main enzymes involved in bacterial anaerobic corrosion of metals. The study of their mode of action is important for a full comprehension of this phenomenon. The three types ofDesulfovibrio hydrogenases [(Fe), (NiFe), (NiFeSe)] present different patterns in the pH dependence of their activity. The periplasmic enzyme fromDesulfovibrio salexigens and the cytoplasmic enzyme fromDesulfovibrio baculatus both have pH optima at 7.5 for H₂ uptake and 4.0 for H₂ evolution and H⁺–D₂ exchange reaction (measured by membrane-inlet mass-spectrometry). The H₂ to HD ratio at pH above 5.0 is higher than 1.0. The periplasmic hydrogenase fromD. gigas presents the same pH optimum (8.0) for the H⁺–D₂ exchange as for H₂ consumption. In contrast, the enzyme fromD. vulgaris has the highest activity in H₂ production and in the exchange at pH 5.0. Both hydrogenases have a H₂-to-HD ratio below 1.0.     

The relationship between hydrogen metabolism,sulfate reduction and nitrogen fixation in sulfate reducers

Summary Hydrogenase and nitrogenase activities of sulfate-reducing bacteria allow their adaptation to different nutritional habits even under adverse conditions. These exceptional capabilities of adaptation are important factors in the understanding of their predominant role in problems related to anaerobic metal corrosion. Although the D₂–H⁺ exchange reaction indicated thatDesulfovibrio desulfuricans strain Berre-Sol andDesulfovibrio gigas hydrogenases were reversible, the predominant activity in vivo was hydrogen uptake. Hydrogen production was restricted to some particular conditions such as sulfate or nitrogen starvation. Under diazotrophic conditions, a transient hydrogen evolution was followed by uptake when dinitrogen was effectively fixed. In contrast, hydrogen evolution proceeded when acetylene was substituted as the nitrogenase substrate. Hydrogen can thus serve as an electron donor in sulfate reduction and nitrogen metabolism.     

Considérations sur la nature,l'origine,et le comportement des elaioplastes chez les Monocotylédones

Résumé L'étude en microscopie photonique et électronique, chez quatre espèces de Monocotylédones, a permis de mettre en évidence en plus de certains caractères concernant leur morphologie et leur répartition, le comportement des élaïoplastes au cours de la mitose et l'origine intracytoplasmique de ces organites sous forme d'amas de vésicules en relation probable avec reticulum endoplasmique. Enfin des rapprochements ont été faits avec les corps centraux des quelques bryophytes et certaines formations particulières aux Desmidiées.

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Summary The study in photonic and electronic microscopy of four species of monocotyledons allowed us to make obvious, in addition to several characteristcs concerning their morphology and repartition, the behaviour of the elaïoplasts during mitosis, and the intracytoplasmic origin of these organelles in the shape of vesicle gatherings probably related to the endoplasmic reticulum. Besides some comparisons have been made with the central bodies of Bryophyts and several formations peculiar to Desmids.

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Zusammenfassung Die licht- und elektronenmikroskopische Untersuchung von vier Monokotyledonenarten ermöglichte uns, zusammen mit bestimmten Kennzeichen ihrer Morphologie und ihrer Verteilung, das Verhalten der Elaioplasten im Laufe der Mitose und die Bildung der Bläschenhaufen, die mit dem endoplasmatischen Reticulum wahrscheinlich in Verbindung stehen, klarzustellen. Schließlich sind Vergleiche mit den Zentralkörpern der Bryophyten und mit gewissen Bildungen, die den Desmidiaceen eigentümlich sind, angestellt worden.