Digestion extracellulaire dans la cavité gastrique de Cerianthus lloydi Gosse. Structure du gastroderme,localisation et propriétés des enzymes protéolytiques

Using histochemical techniques, trypsin and chymotrypsin-like proteases have been detected in the gland cells of enteroids in the gastroderm of Cerianthus lloydi Gosse.These enzymes seem to be concentrated in granules resembling the zymogen granules of mammalian pancreas; the mechanisms of synthesis and the form of their membranes seem to be the same. Trypsin and chymotrypsin of C. lloydi resemble the vertebrates enzymes with respect to their properties and reaction with certain substrates and inhibitors.Trypsin appears to exist as an inactive precursor in the gastroderm of C. lloydi with spontaneous activation at 25°C.     

Ultrastructure de l'ectoderme des tentacules labiaux et marginaux de Pachycerianthus fimbriatus McMurrich

In Pachycerianthus fimbriatus McMurrich, collar cells have been found in the ectoderm layer of marginal and labial tentacles. Villi, nematocytes, spirocysts, two types of mucous gland cells, and trypsinogen gland cells have been described. We have failed to discover special apical structures linked with the uptake of ferritin in solution. The rôle of apical villi and collar cells is discussed.     

Action de l'hormone juvenile et de certains mimetiques sur l'epithelium intestinal chez Galleria mellonella

We have investigated the influence of juvenile hormone (JH) on the intestinal epithelium of G. mellonella, in vivo and in vitro. The larvae undergoing a supernumerary instar present a typical larval epithelium with columnar (CL) and globlet (CF) cells; the spinning period is characterized by a delay and a loss of synchronism in the process of differentiation of intermediates cells (Ci) typical of the pharate pupa. The larval-pupal intermediates show true mosaïcs in which Ci and CF are juxtaposed; however, the ratio of Ci in the epithelium progressively increases.The injection of JH at the beginning of spinning induces the appearance of CF just as Ci should normally grow. Hormone administration during the second half of the spinning period modifies the differentiation of epithelial cells: they become taller. We consider them to be cells engaged in pharate pupal differentiation, and which have then been partially oriented toward larval differentiation.These results show that the intestinal epithelium is a competent tissue, the sensibility of which to JH, is higher than that of the epidermis. The basal cell plasticity is very important and the action of JH on their differentiation may lead to CL or CF, to tall cells, and to Ci, depending on hormonal rate. In vitro, the experiments show that the action of JH is probably direct on the target tissue. The fact that JH can act very late as a modifier of the differentiation of the growing epithelial cells exclude the possibility that the hormone exercises its control through DNA replication.     

Compartments in Scyphozoa

Polyps of Scyphozoa have a cup-shaped body. At one end is the mouth opening surrounded by tentacles, at the other end is an attachment disc. The body wall consists of two tissue layers, the ectoderm and the endoderm, which are separated by an extracellular matrix, the mesoglea. The polyp's gastric cavity is subdivided by septa running from the apical end to the basal body end. The septa consist of two layers of endoderm and according to biology textbooks the number of septa is four. However, in rare circumstances Aurelia produces polyps with zero, two, six, or eight septa. We found that the number was always even. Therefore we propose that two types of endoderm exist, forming alternating stripes running from the oral body end to the aboral end. The stripes have some properties of developmental compartments. Where cells of different compartments meet, they form a septum. We also propose that the ectoderm is subdivided into compartments. The borders of the ectodermal and endodermal compartments are perpendicular to each other. Tentacles of the polyp and rhopalia (sense organs) of the ephyra (young medusa), respectively, develop at the border between two ectodermal compartments. The number can be even or odd. Rhopalia formation is particularly favored where two ectodermal and two endodermal compartments meet.     

Phenylpolyenes d'Aspergillus niger: structure et proprietes de l'asperrubrol

When grown on a synthetic medium containing Zn²⁺ and Cd²⁺ in toxic concentrations and a high concentration of Mg²⁺, the mycelium of Aspergillus niger ATCC 9029 is pigmented yellow. Four pigments have been chromatographically separated. Two are still unknown; the others are asperenone and asperrubrol. Asperrubrol is the methyl ester of a dimethyl 13-phenyl-3-ol-2,4,6,8,10,12-tridecahexaenoic acid. One of the methyl groups is on C₂ and the other is probably at C₈. Asperrubrol has been obtained as the enol of the all trans molecule; ketoe nolisation can be obtained by action of heat or alkalis. When grown on the same medium, 13 of 17 strains of A. niger produced asperrubrol and asperenone.     

Sur quelques echinodermes(Cystoides et Crinoides) de l'Ashgill d'Aragon (Espagne)

The material collected in the outcrops of Fombuenaand Luesma allows to specify the distinctive characters of the genera Corylocrinus and Caryocrinites, to describe two new species and to complete the morphology of Heliocrinites rouvillei and Proteocystites hispanica. The Crinoid association of these localities shows a very close composition with that of Coat-Carrec (Finistère). The new observations establish definitively the structure of the dorsal cup and the oral face of Mespilocystites. The occurence of the genera Stichocystis, Eucystis and Mespilocystites is recorded for the first time in Aragon. Cystoids and Crinoids confirm the existence of Ashgillian in the western part of the Armorican Massive.     

Role des spermatheques dans l'utilisation du sperme et la stimulation de l'ovogenese chez Drosophila melanogaster

Fecundity and fertility of Drosophila females were studied after extirpation of one or two spermathecae. When extirpated females were mated only once, egg deposition was slightly accelerated but total egg production, during twelve days, was the same as in virgin operated females. Egg hatchability was high during two days but decreased more rapidly than in normal or sham-operated femalesWhen males were permanently kept with females, egg production and egg hatchability of operated females remained at a high level during the experiment. In that case, females could copulate frequently and the increase in egg production is interpreted as a consequence of paragonial fluid stimulationThe most significant rôle of spermathecae seems therefore to assume the transmission of the sperm stimulus to the brain; they probably also improve the survival capacities of sperm.     

Modifications de l'équipement endocrine et morphogenèse génitale chez l'embryon de Carausius

It has previously been shown that in Carausius the mechanisms ensuring normal, i.e. female, differentiation of the genital rudiment can be deflected towards male differentiation. A study of bicephalic monsters and microsurgical experiments show that the genital anlage is not affected by a lack or an excess of neurosecretory or allatal components. However, experiments show that the prothoracic glands (=ventral cephalic glands) play an important part in the development of the genital anlage.     

Incorporation de phenylalanine,de glucose et d'acide cinnamique dans les flavonols de l'oignon

In Allium cepa bulb scales, incorporation of ¹⁴C-phenylalanine, cinnamic acid and glucose were studied in relation to flavonol synthesis. The best incorporation into flavonols is obtained with either cinnamic acid or phenylalanine. ¹⁴C-glucose gives a slow incorporation into flavonol aglycone; this is because there is a big pool of free glucose in the scales in which the precursor is diluted. Under certain conditions, free cinnamic acid is quickly incorporated in a complex which may be a glycoside. After short labelling experiments with phenylalanine or cinnamic acid, some free precursor can be found in the scales a few days later but it is not available for flavonol synthesis. In these conditions, flavonol analysis shows in some cases, no turnover and in others, a turnover of 10% per day due to catabolism.     

THE CERIANTHAR1AN NERVOUS SYSTEM

Evidence supporting the presence of nerve cells in the columnand tentacles of Pacliycerianthiis is described. G. F. Gwilliamhas shown that electrical stimuli can be transmitted to theectodermal muscle by the intact epithelium and subepithelialnetwork of the ectoderm of the column. In these preparationsthe ectodermal muscle, mesogloea, and endoderm were cut. Incontrast, preparations in which the ectodermal muscle has beenleft intact and the epithelium and subepithelial network cutdo not show such transmission. The author and Gwilliam have independently used different silverstain methods to demonstrate large cells, piobably nerve cells,with cell bodies in the base of the epithelium and with fibersrunning into the subepithelial network. The author has foundsimilar bipolar cells in the tentacles and column by using macerationtechniques. These cells are compared with other cell types foundin the tentacles.     

Variations du taux d'amp cyclique et des activités spécifiques de l'adénylate cyclase et de l'amp cyclique-phosphodiestérase pendant le cycle cellulaire d'un actinomycète

The variations in the concentrations of intra- and extracellular cyclic AMP and in the specific activities of adenylate cyclase (EC 4.6.1.1) and cyclic AMP phosphodiesterase (EC 3.1.4.17) have been monitored in synchronized culture of Nocardia restricta, a prokaryote belonging to the group of Actinomycetes. At the beginning of the cell cycel, during a first period of RNA and protein synthesis, there is an increasing synthesis of adenylate cyclase which can be suppressed in the presence of chloramphenicol or rifampicin. Simultaneously, the specific activity of cyclic AMP phosphodiesterase decreases and the concentrations of intra- and extracellular cyclic AMP rise. After the end of DNA replication, during a second period of RNA and protein synthesis, the specific activity of cyclic AMP phosphodiesterase increases; during the same time, the specific activity of adenylate cyclase and the level of intracellular cyclic AMP drop. It appears that the overall metabolism of cyclic AMP is coordinated so that the cyclic AMP level will be high at the beginning of DNA replication and will fall thereafter. The results are discussed in comparison with known data about the variations of cyclic AMP during the cell cycle of mammalian cells in cultures.     

Molécules organiques dissoutes dans l'eau de mer: Utilisation de l'acide palmitique,de l'alcool cétylique et du dotriacontane par les invertébrés marins

It has been shown previously that 16-¹⁴C palmitic acid, 1-¹⁴C cetyl alcohol and 16,17-¹⁴C dotriacontane dissolved in sea water are rapidly incorporated into the oyster Ostrea gryphea L. and the sea anemone Calliactis parasitica Couch. In the present communication, we establish that palmitic acid and cetyl alcohol are slowly metabolized, but the hydrocarbon dotriacontane is unchanged after 48 h. The results are discussed.     

Decouverte de Planomalina buxtorfi (gandolfi) et d'autres foraminiferes plancotoniques inattendus dans l'albien superieur d'abbotscliff (kent,angleterre); consequences paleogeographiques et biostratigraphiques

The discovery of Planomalina buxtorfi (GANDOLFI) in the Upper Albian (Stoliczkaia dispar zone) of Abbotscliff (Kent, England), associated with Rotalipora appenninica (RENZ), Praeglobotruncana delrioensis (PLUMMER), Hedbergella simplex (MORROW) and Hedbergella costellata SAINT MARC, appreciably modifies data on the geography and stratigraphical distribution of these species in the boreal realm.     

Dosage de l'hémisuccinate de benfurodil dans le sang et l'urine par chromatographie en phase liquide haute pression

High-pressure liquid chromatographic determination of benfurodil hemisuccinate in blood and urineA sensitive and reliable method for quantitative determination of benfurodil hemisuccinate and benfurodil in plasma by high-pressure liquid chromatography on a Zorbax SIL column with a mean particle size of 7 μm and UV detection at 254 nm is described.Benfurodil hemisuccinate is stable in plasma but not in aqueous solutions. This is explained by its great fixation to plasma proteins which has been shown by equilibrium dialysis.     

Cripto is required for mesoderm and endoderm cell allocation during mouse gastrulation

During mouse gastrulation, cells in the primitive streak undergo epithelial–mesenchymal transformation and the resulting mesenchymal cells migrate out laterally to form mesoderm and definitive endoderm across the entire embryonic cylinder. The mechanisms underlying mesoderm and endoderm specification, migration, and allocation are poorly understood. In this study, we focused on the function of mouse Cripto, a member of the EGF-CFC gene family that is highly expressed in the primitive streak and migrating mesoderm cells on embryonic day 6.5. Conditional inactivation of Cripto during gastrulation leads to varied defects in mesoderm and endoderm development. Mutant embryos display accumulation of mesenchymal cells around the shortened primitive streak indicating a functional requirement of Cripto during the formation of mesoderm layer in gastrulation. In addition, some mutant embryos showed poor formation and abnormal allocation of definitive endoderm cells on embryonic day 7.5. Consistently, many mutant embryos that survived to embryonic day 8.5 displayed defects in ventral closure of the gut endoderm causing cardia bifida. Detailed analyses revealed that both the Fgf8–Fgfr1 pathway and p38 MAP kinase activation are partially affected by the loss of Cripto function. These results demonstrate a critical role for Cripto during mouse gastrulation, especially in mesoderm and endoderm formation and allocation.     

Differential response of epiblast stem cells to Nodal and Activin signalling: a paradigm of early endoderm development in the embryo

Mouse epiblast stem cells (EpiSCs) display temporal differences in the upregulation of Mixl1 expression during the initial steps of in vitro differentiation, which can be correlated with their propensity for endoderm differentiation. EpiSCs that upregulated Mixl1 rapidly during differentiation responded robustly to both Activin A and Nodal in generating foregut endoderm and precursors of pancreatic and hepatic tissues. By contrast, EpiSCs that delayed Mixl1 upregulation responded less effectively to Nodal and showed an overall suboptimal outcome of directed differentiation. The enhancement in endoderm potency in Mixl1-early cells may be accounted for by a rapid exit from the progenitor state and the efficient response to the induction of differentiation by Nodal. EpiSCs that readily differentiate into the endoderm cells are marked by a distinctive expression fingerprint of transforming growth factor (TGF)-β signalling pathway genes and genes related to the endoderm lineage. Nodal appears to elicit responses that are associated with transition to a mesenchymal phenotype, whereas Activin A promotes gene expression associated with maintenance of an epithelial phenotype. We postulate that the formation of definitive endoderm (DE) in embryoid bodies follows a similar process to germ layer formation from the epiblast, requiring an initial de-epithelialization event and subsequent re-epithelialization. Our results show that priming EpiSCs with the appropriate form of TGF-β signalling at the formative phase of endoderm differentiation impacts on the further progression into mature DE-derived lineages, and that this is influenced by the initial characteristics of the cell population. Our study also highlights that Activin A, which is commonly used as an in vitro surrogate for Nodal in differentiation protocols, does not elicit the same downstream effects as Nodal, and therefore may not effectively mimic events that take place in the mouse embryo.     

Disruption of Sphingolipid Biosynthesis Blocks Phagocytosis of Candida albicans

The ability of phagocytes to clear pathogens is an essential attribute of the innate immune response. The role of signaling lipid molecules such as phosphoinositides is well established, but the role of membrane sphingolipids in phagocytosis is largely unknown. Using a genetic approach and small molecule inhibitors, we show that phagocytosis of Candida albicans requires an intact sphingolipid biosynthetic pathway. Blockade of serine-palmitoyltransferase (SPT) and ceramide synthase-enzymes involved in sphingolipid biosynthesis- by myriocin and fumonisin B1, respectively, impaired phagocytosis by phagocytes. We used CRISPR/Cas9-mediated genome editing to generate Sptlc2-deficient DC2.4 dendritic cells, which lack serine palmitoyl transferase activity. Sptlc2^-/- DC2.4 cells exhibited a stark defect in phagocytosis, were unable to bind fungal particles and failed to form a normal phagocytic cup to engulf C. albicans. Supplementing the growth media with GM1, the major ganglioside present at the cell surface, restored phagocytic activity of Sptlc2^-/- DC2.4 cells. While overall membrane trafficking and endocytic pathways remained functional, Sptlc2^-/- DC2.4 cells express reduced levels of the pattern recognition receptors Dectin-1 and TLR2 at the cell surface. Consistent with the in vitro data, compromised sphingolipid biosynthesis in mice sensitizes the animal to C. albicans infection. Sphingolipid biosynthesis is therefore critical for phagocytosis and in vivo clearance of C. albicans.     

An intermediate type of medusa from the early Cambrian Kuanchuanpu Formation,South China

The tetraradial or pentaradial fossil embryos and related hatched individuals from the early Cambrian Kuanchuanpu Formation are of great interest for understanding the early evolution of medusozoans. The phylogenetic and evolutionary significance of their external and internal characters (e.g. manubrium, tentacles, septa and claustra) is still controversial. Here we describe a new pentamerous medusozoan, Hanagyroia orientalis gen. et sp. nov., characterized by five well-developed perradial oral lips around a remarkably large manubrium, a conspicuous equatorial groove, and five short interradial pairs of extensile tentacles at the bell margin. Internally, five broad and stout interradial septa join horizontally to form the claustra. Hanagyroia orientalis lacks the frenula, apertural lappet and velarium seen in coeval microfossils and extant cubozoans. Although H. orientalis resembles extant coronate scyphozoans in its round medusa-like bell margin and equatorial groove, cladistic analysis suggests close affinity with cubozoans. Hanagyroia may represent an intermediate morphological type between scyphozoans and cubozoans. The well-developed oral lips and paired short strong tentacles of Hanagyroia suggest direct development.     

Diverses proprietes de l'absorption du citrate du malate et du succinate par les lutoides du latex d'Hevea brasiliensis

Lutoïds from Hevea latex are microvacuoles with lysosomal character. In vitro in a medium free of energetic substrate citrate, malate and succinate are absorbed. The properties of this absorption and the action of some modifiers are discussed.