Évolution horaire au cours d'une journée normale de la photosynthèse, de la transpiration, de la respiration foliaire et racinaire et de la nutrition N.P.K. chez Zea mays

Hourly development during a normal day of photosynthesis, transpiration, leaf and root respiration, and of N.P.K nutrition in Zea mays. Metabolism of Zea mays L. cv. INRA F₇×F₂ can be measured hourly with the “C₂3A system”, under favourable and constant growth conditions. The photosynthesis is especially stable and is submitted only to a development linked with the leaf surface growth. During the vegetative stage the leaf surface increases regularly both in the day and in the night. The water loss does not change during the diurnal period and remains important during the night if humidity is less than 100%. The leaf respiration is nearly stable. The root respiration, measured with O₂ and CO₂, fluctuates according to a typical rhythm with two maxima. Day and night mean rates were about the same. The respiratory quotient is about one during the vegetative stage. There is no decrease in the rate of phosphate absorption during the night, and a very small decrease in the rate of nitrate absorption. Ammonium is totally consumed in the first hours after renewal of the nutrient solution. At the same time the potassium consumption is decreased, and then presents a maximum followed by a night reduction. Under our conditions, all of the observations allowed us to assume the presence of an adequate reserve of assimilates and suggest the existence of a precise regulation process, which can ensure an even day night functioning of the plant metabolism, but which does not preclude the presence of internal rhythms, as indicated by the oscillation of the root respiration.     

Ultrastructure de la spermiogenèse et du spermatozoïde de Loimosina wikoni et affinités phylétiques des Loimoidae (Plathelminthes, Monogenea, Monopisthocotylea)

In Loimosina, during spermiogenesis, the zone of differentiation of the spermatid contains two centrioles continued as two 9 +‘1’axonemes. One of the axonemes lengthens and will become the principal axoneme of the spermatozoon. The other axoneme is as long as the first one at the beginning of spermiogenesis, but is shorter in the mature sperm cell. The spermatozoon consists of several regions: (a) at the anterior end, the centriolar derivative of the principal axoneme; (b) a short region which shows cortical microtubules coinciding with external ornamentations; (c) a long uniflagellate region, with mitochondrion; (d) a biflagellate region containing the anterior slender part of the nucleus; (e) the posterior part of the nucleus, with no accompanying cytoplasmic organelles. Spermiogenesis and sperm structure in Loimosina differ from what is known in all other described monogeneans, excepting the monocotylid Heterocofyle to which they show close resemblances. However, the alteration of the second axoneme is more complete in Heterocofyle than in Loimosina. Comparative study of spermiogenesis and sperm ultrastructure thus shows an interesting coincidence with classical phylogenies of the monogeneans, in which the families Loimoidae and Monocotylidae are closely related. Chez Loimosina, pendant la spermiogenèse, la zone de différenciation de la spermatide contient deux centrioles prolongés par deux axonemes de type 9 +‘1′. L'un des axonemes s'allonge et deviendra l'axonème principal du spermatozoïde mûr. Le deuxième axontme est aussi long que le premier au début de la spermiogenèse, mais il est plus court dans le spermatozoïde mûr. Le spermatozoïde comprend: (a) à l'avant, le dérivé centriolaire de l'axonème principal; (b) une courte région contenant quelques microtubules corticaw longitudinaux coincidant avec des omementations extramembranaires; (c) une longue région miflagellée avec mitochondrie; (d) une région biflagellée contenant La partie antérieure effilée du noyau; (e) la région postérieure du noyau, sans organites cytoplasmiques accompagnateurs. La spermiogenèse et la structure du spermatozoïde de Loimosina sont différentes de ce qui est connu chez tous les autres Monogènes décrits, excepté le Monocotylidae Heterocofyle auquel elles ressemblent beaucoup. Toutefois, l'altération du deuxième axonème est moins complète chez Loimosina que chez Heterocotyle. L'étude comparée des spermatozoïdes et des spermiogenèses montre une bonne coincidence avec les phylogenèses classiques, dans lesquelles les familles Loimoidae et Monocotylidae sont proches.     

Synthèse et structure de la poly-O-carbobenzoxy L- tyrosine et de copolymères de O-carbobenzoxy L-tyrosine et de glutamate de benzyle ou d'aspartate de benzyle

The optical rotatory dispersion of copolymers of O-carbobenzoxy-L -tyrosine and benzyl L (or D )-glutamate as well as benzyl L -aspartate, dissolved in nonpolar solvent, has been studied. Moffitt's equation permits the determination of b₀ coefficients whose variation, with varying composition in amino acid residues, suggests that the molecules of poly-O-carbobenzoxy-L -tyrosine have a helical structure similar to that of poly-(benzyl L -glutamate). Results obtained from infrared spectroscopy and x-ray diffraction show that the copolymers possess a helical conformation in the solid state, even when they are very rich in carbobenzoxy-L -tyrosine residues. The value of the b₀, coefficient for poly-O-carbobenzoxy-L -tyrosine may be explained by a regular stacking of the chromophore groups around the helical backbone. The ordering of the molecules of this polymer in a purely helical structure seems favored by the insertion of a small number of foreign residues in the polypeptide chain.     

Espaces de réclusion et de rassemblement et expression graphique au Néolithique

Space is an inescapable data to analyse the schematic graphic expression in the Neolithic age and the practices, which are linked with it. A sign has meaning according to its place on the wall, in the shelter and in the area of decorated sites. We suppose that these painted shelters, and widely, the space where they are included, are visited during transition rites. Some of these sites have probably been used for persons in cloistered status. Others shelters are more areas for the gathering of an important group of men. We think that cloistering and gathering are adaptable with the diversity of environment. The Van Gennep's explanation of transition rites in three parts and the spatial analysis allow us to explain the transition and transformation of men on the decorated sites.     

Le Protoaurignacien : première culture de l'homme moderne de Provence et Ligurie

G. Laplace defined the Protoaurignacian in Liguria (“abri Mochi”) as the earliest occurrences of Upper Paleolithic in Italy. Stratigraphic sequences in Var exemplify that the Protoaurignacian is the first sequence of Upper Paleolithic in Provence and widely different from classic Aurignacian defined in southwestern France. Recorded in Languedoc-Roussillon, that one is documented in some other stratigraphic sequences from Monaco to southern Spain (“cueva del boquete de Zafarraya”). The Protoaurignacian argue that first modern humans arrived and occupied all along the Mediterranean coasts from Gibraltar to Toscana.     

Morphologie et Ultrastructure de Spirochona gemmipara Stein, 1852 (Ciliophora,Chonotrichida). II. Appareil Cytoproctal et Système Excréteur de I'Adulte1

ABSTRACT. Examination of the anterior region of Spirochona gemmipara by combined use of interference contrast microscopy, protargol staining, and transmission electron microscopy has revealed the existence of a cytoproctal apparatus and of an excretory system (contractile vacuole complex), that have often been confused with each other and with the cytopharynx. The cytoproctal apparatus is comprised of an external orifice located at the base of the collar, a cytoproctal canal that is about 20 μm long and delimited by a pellicle with alveoli, and the cytoproct itself. The contractile vauole complex is composed of 6–8 sinuous canals, up to 20 μm long, each of which opens to the exterior by a pore situated among the ciliature of the collar. An ostium, which is the internal orifice of each canal, is connected with a contractile vacuole that is contiguous with a well developed tubular spongiome. Although deeply set, the cytoproct and ostia of S. gemmipara do not appear to be basically different from the corresponding structures described in Paramecium and Tetrahymena.