Lysosomes of root tip cells in corn seedlings

Summary Nine acid hydrolases are present in lysosomes which are found in the mitochondrial fraction of a cell-free extract prepared from root tips of corn seedlings.Light and heavy lysosomes can be distinguished. The latter are sedimentable in a sucrose-medium, the former only in sorbitol-medium. The fraction of heavy lysosomes is in turn composed of at least three populations of lysosomes differing in density and enzyme content.Light lysosomes are membrane-bound particles with diameters from 0.3 to 1.5 . Electron micrographs of frozen-etched tissue and isolated particles provide evidence that light lysosomes are identical with small vacuoles. This type of lysosome is characterized by presence of transaminases in addition to that of hydrolases. Heavy lysosomes are small spheres (diameters from 0.1–0.3 ) with membranes resembling those of vacuoles and of the endoplasmic reticulum. These lysosomes are characterized by high specific activities of two oxydoreductases known to occur also in the membranes of the reticulum.The different types of particles are thought to represent stages of the development of the lysosomal apparatus; according to this hypothesis the large vacuole of parenchymatous cells represents the end product of this process.     

Étude pédologique comparative de l'habitat et de l'environnement d'anacanthotermes ochraceus (Burgmeister)

Summary Anacanthotermes ochraceus (Burgmeister), in the oasis of Béni-Abbès (Sahara) will establish its colonies only in the low eathern garden walls and in the clay and straw walls of the houses, where it can find both the water and the malleable clayed materials it requires.Soil analyses have given information on the physico-chemical characteristics of some of the termitaria and of the surrounding sand-hill.The organic matter in the termitarium comes both from the soil and the excrement of the termite. It is high in carbon and low in nitrogen (C/N=2,5), and its mineralization in the présense of gravitational water may result in a loss of mobilizable elements such as the bases.Both the Ph and the aeration of the termitarium favour the mineralization of nitrogenous waste material by bacterial agency.The distribution of calcium carbonate and the condition in which it occurs are more important than the total amount present on account of the part it plays in the texture and structure of the materials, of which the termitarium is composed.A statistical granulometric study of the sand fraction with the results expressed as polar coordinates enables, in comparison with those obtained by mechanical analysis, the texture of the materials colonised byAnacanthotermes ochraceus (Burgmeister) to be defined.

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Zusammenfassung In der Oase Béni-Abbés (Sahara) gründen dieAnacanthotermes ochraceus (Burgmeister) ihre Kolonien nur in den Wänden der Gärten und in den Mauern der Wohnungen. Dort finden sie das nötige Wasser und die tonigen Plastikmaterialien.Die Bodenanalysen geben Auskunft über einige der characteristichen physikalischchemischen Eigenschaften der Materialien in der Termitenbauten und in dem benachbartem Erg.Das organische Material in den Termitenbauten stammt einerseits aus dem Boden und andererseits aus den Ausscheidungen der Termiten. Reich an Kohlenstoff und arm an Stickstoff (C/N=2,5) kann seine Mineralisation, in Gegenwart von gravifischem Wasser, einen Verlust von einsatzfähigen Elementen, wie den Laugen, nach sich ziehen.Die Bedingungen des Ph und der Belüftung der Termitenbauten sind günstig für eine Mineralisation der stikstoffhaltigen Abfallstoffe auf bakteriellem Wege.Die Verteilung und die Beschaffenheit des CO₃Ca sind dort wichtiger als ihre Gesamtauswertung. Der Grund dafür ist die Rolle, die sie auf der Ebene der Textur und des Aufbaus der Materialen in den Termitenbauten spielen.Die Untersuchung der sandigen Bruchstücke durch die granulometrischen Statistiken in Polarkoordinaten, verglichen mit den Ergebnissen der granulometrischen Analyse, erlauben eine Erklärung der Textur der mit Beschlag belegten kolonisierten Materialen durch dieAnacanthotermes ochraceus (Burgmeister).