Le collagène du byssus de Mytilus edulis L.

Résumé L'autoradiographie révèle, au niveau du pied, une incorporation massive et sélective de la ³H-Proline dans la glande blanche de Mytilus edulis. Cette étude a permis de suivre le processus qui mène de la synthèse de la sécrétion dans la partie basale des cellules jusqu'a son émission dans le sillon pédieux où elle participe à la formation du filament. La collagénase détruit la presque totalité du marquage, attestant ainsi la nature collagénique du produit sécrété. Les autres glandes pédieuses ainsi que la glande du byssus proprement dite, située à la base du pied, montrent une incorporation très faible, sans commune mesure avec celle de la glande blanche. Ceci démontre de façon définitive que le collagène présent dans le filament prend naissance dans cette glande et justifie la dénomination de glande du collagène. Des contrôles réalisés dans différentes régions (bords du manteau, manteau, branchies) montrent que l'injection du précurseur dans le bord palléal constitue une méthode satisfaisante pour marquer de façon relativement rapide et différentielle le collagène de la glande.

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The collagen of the byssus in Mytilus edulis L.II. Autoradiographic study on the incorporation of ³H-Proline

Summary Autoradiographic studies reveal a strong specific incorporation of ³H-Proline in the white gland in the foot of Mytilus edulis. The author could trace the radioactive secretory product from its synthesis in the basal part of the cells down to its outflow into the pedial groove where it takes part in the formation of the filament. Purified collagenase takes out radioactivity from the sections. This observation confirms the collagenous nature of the secretion.The other foot-glands as well as the main byssus gland located at the base of the foot show but a very weak labelling not comparable with that of the white gland. This clearly evidences that the collagen occuring in the filament originates from the latter. The white gland may be properly called: collagen gland.Control sections through different parts of the body (mantle-edge, mantle, gills) confirm that our injection technique of the precursor into the palleal margin is a suitable method for a rather quick and specific labelling of the glandular collagen.

Cette note fait partie d'un travail pour l'obtention d'une thèse de doctorat.     

The status of the genera Hysterolecithoides Yamaguti, 1934, Neotheletrum Gibson & Bray, 1979 and Machidatrema León-Règagnon, 1998 (Digenea: Hemiuroidea), including a description of M. leonae n. sp. from Australian waters

A diagnosis is given for the lecithasterid genus Hysterolecithoides Yamaguti, 1934, which is now found to have two to six (possibly seven) vitelline masses. The species H. frontilatus (Manter, 1969) is returned to the genus, having been considered a member of the bunocotylid genus Neotheletrum by recent authors. It is redescribed from Siganus nebulosus, Moreton Bay, and S. doliatus, Lizard Island, Great Barrier Reef and New Caledonia, with emphasis on the presence of Juel's organ, a uterine seminal receptacle and the blind sac associated with the genital atrium. It differs from its congeners in the trajectory of the pars prostatica which recurves dorsally to the sinus-sac. Oligolecithoides Shen, 1982 is synonymised with Hysterolecithoides and O. trilobatus Shen, 1982 is synomised with H. epinepheli Yamaguti, 1934. Machidatrema León-Règagnon, 1998 is diagnosed, and found to be close to Hysterolecithoides, but differs in the lack of a blind-sac projecting from the dorsal genital atrium, by its tandem testes, the coiling of the uterus between the testes and the ovary, and the ventral excretory pore. M. leonae n. sp. is described from Siganus fuscescens, S. lineatus, S. doliatus, S. corallinus, S. vulpinus and Scarus globiceps at Heron Island, Queensland. It differs from its closest congener, M. akeh, in the muscular and tegumental flap over the genital pore and details of the terminal genitalia. M. chilostoma (Machida, 1980) and M. kyphosi (Yamaguti, 1970) are redescribed from Kyphosus vaigiensis from Heron Island. Neotheletrum Gibson & Bray, 1979 is diagnosed: it differs from Hysterolecithoides in its confluent excretory arms, blind seminal receptacle (no Juel's organ) and uniformly tripartite vitellarium. A cladistic analysis suggests that M. chilostoma and M. kyphosi are not best accommodated in Machidatrema, that Machidatrema (sensu stricto) is monophyletic and that Hysterolecithoides is paraphyletic. Hysterolecithoides and Machidatrema are considered hysterolecithine lecithasterids, whilst Neotheletrum is retained as an opisthadenine bunocotylid.     

Contribution à l'analyse des structures forestières 1. Le grain des dominances

A method of simultaneous analysis of vertical and horizontal structure is described. It is particulary applicable to forest and shrubland. Data come from point-height analysis of vegetation: 100 sample points are arranged in 4 lines of 25, with 2 m between lines and 1 m between points on lines. At each point, specific lists of spaces intercepted optically are observed by vertical measurement strata. Strata depth is 10 cm when mean vegetation height is lower than 4–5 m, and 50 cm above this height. This study is based on height of upper vegetation presence, and applied to low forests ofNothofagus antarctica (Forest.)Verst. in Southern Chile and Argentina. The authors summarize the data sequence by the cumulative sum technique. This technique allows the rapid and clear delimitation of three dimensional mosaic units of vegetation whose height varies vertically from the mean height. The pattern of these mosaic units is shown as three dimensional block diagrams, giving a good representation of structural dominance patterns.     

Ephemerella readeri Müll. Hal. (Physcomitrella readeri (Müll. Hal.) I.G. Stone & G.A.M. Scott,Funariidae, Bryophyta): a genus and species new to Europe

Abstract

A morphological and molecular analysis of a Physcomitrella, collected from a reservoir margin in the north of England, revealed this to be P. readeri, a species new to Europe. The present study clarifies previous confusion over the taxonomy of P. readeri showing it to be clearly distinct in both sporophytic and gametophytic characters from P. patens and uniform across its world range from England to USA, Japan and Australasia. While phylograms of the ITS1 region from both the Physcomitrella species, Physcomitrium pyriforme (Hedw.) Bruch & Schimp., Enthosthodon attenuatus (Dicks.) Bryhn and Funaria hygrometrica Hedw., place the first two in separate clades, in ITS2 phylograms they occur as sister taxa. This, together with previous genealogical studies on the speciation history of the Physcomitrella–Physcomitrium species complex, and morphology, suggests that generic rank is appropriate for P. readeri. We therefore reinstate the original name Ephemerella readeri Müll. Hal. Recent records at several reservoirs in England indicate that E. readeri may be native to UK, though remarkable congruence in ITS1 with Australian plants also suggests recent arrival as an alternative possibility.