Evidence for an association between calmodulin and membrane patches containing gonadotropin-releasing hormone — receptor complexes in cultured gonadotropes

Summary Participation of calmodulin, clathrin, and actin in receptor mediated endocytosis of gonadotropin-releasing hormone (GnRH) was studied in an in vitro system of dispersed pituitary cells with a triple staining procedure. Cells were incubated in D-Lys⁶-Pro⁹-Des¹⁰-GnRH-biotin and stained with avidin-peroxidase-diaminobenzidine. Calmodulin, clathrin, and actin as well as luteinizing hormone were identified by indirect immunofluorescence with FITC- and rhodamine-labeled second antibody. The results indicate a close spatial association of calmodulin, but not of clathrin and actin, with GnRH-containing plasma membrane patches.Supported by PHS grants NIH NS1761401, HS 09914, and HD 19899     

Preparation of h and m antigens ofHistoplasma capsulatum free of heterologous antigens

Salt gradient elution of crude histoplasmin on CM-Sepharose CL6B at pH 3.0 was used in essentially a one-step procedure to isolate the h, m, and non-m antigens ofHistoplasma capsulatum and free them of any c antigen common to other pathogenic fungi. The h antigen fraction was pure; the isolated m and non-m antigens contained less than 0.1% of the c antigen present in the original preparation. The residual c antigen in these fractions was removed by affinity chromatography on Affigel-10 coupled to aBlastomyces dermatitidis fungal antiserum. The final preparations of h, m, and non-m were pure when tested by immunodiffusion (ID), sodium-dodecyl-sulfate-polyacrylamide-gel electrophoresis (SDS-PAGE), or electrofocusing. The antigens were serologically stable at neutral pH for at least three months at 10°C. The relative molecular weights, isoelectric points, and amino acid composition of the antigens are described.     

Myelogenesis and estimation of the number of axons in the anterior commissure of the chick (Gallus gallus)

Summary By use of light- and electron microscopy the anterior commissure of the chick was studied at different times during development. Between the 19th day of incubation and the 35th day after hatching the cross-sectional area of the anterior commissure, as determined from mid-sagittal sections, undergoes a 6-fold increase in size. Thereafter the area remains fairly constant. The total number of fibres in the anterior commissure was estimated to be 89000. The full complement of fibres is already present by the 19th day of incubation. Myelogenesis occurs mainly between the 19th day of incubation and the 35th day after hatching, concomitant with the increase in cross-sectional area. From the 35th day after hatching, myelinated fibres comprise approximately 40% of the total number of fibres. The median diameter of unmyelinated fibres is about 0.35–0.40 m. The median diameters of myelinated axons and fibres are 0.8–1.0 m and 1.1–1.3 m, respectively.     

A review of the genusChironomus (Diptera,Chironomidae)

Two cytologically distinguishable species have been found in material ofChironomus australis. These species have been calledCh. australis andCh. duplex. Both belong to thepseudothummi-cytological grouping because they have the chromosome arm combinations AE, BF, CD, G.Ch. duplex shows a modified arm pattern due to a tandem fusion of arm G to arm E.—The banding patterns of the polytene chromosomes of the two species are compared to each other and to the Australian standard species,Ch. oppositus. Ch. australis is very close cytologically toCh. oppositus, whileCh. duplex, which is considered a derived species because of the tandem fusion, shows a number of inversion differences from the morphologically similarCh. australis. Ch. duplex is polymorphic for six inversions, four of which are simple inversions, the other two are complex involving also the transposition of some bands.Ch. australis appears to be monomorphic.     

Unterschiede im angriffsverhalten vonFormica-arten (Hymenoptera,Formicidae) gegenüber lycaenidenraupen (Lepidoptera)

Zusammenfassung VonFormica (Serviformica) rufibarbis, F. (S.) cunicularia undF. (Raptiformica) sanguinea werden die sonst an Ameisen angepassten Lycaenidenraupen nur in unmittelbarer Nähe des Nesteinganges eines Ameisennestes angegriffen. BeiF. (F.) rufa ist diese Agressivität nicht raum-, sondern vermutlich stimmungsabhängig. Bei verglichenen anderenFormica-Arten trat sie nicht auf.

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Summary Lycaenid caterpillars which usually are adapted to the aggressive behavior of ants are, despite of their adaptations, attacked byFormica (Serviformica) rufibarbis, F. (S.) cunicularia, F. (Raptiformica) sanguinea, andF. (F.) rufa. In the three first-mentionned species this agression happens only in the immediate neighborhood of the entrance to an ant-hill. On the contrary the aggressivity ofF. rufa seems to depend upon the actual mood of the ants but not upon the distance to an entrance. In other species of the genusFormica compared in experiments with Lycaenid larvae no aggressive behavior was observed.

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Résumé Formica (Serviformica) rufibarbis, F. (S.) cunicularia etF. (Raptiformica) sanguinea n'attaquent les chenilles de Lycénides normalement adaptées aux fourmis qu'à proximité immédiate d'une entrée de la fourmilière. ChezFormica (F.) rufa, cette agressivité ne dépend pas du lieu, mais probablement de l'humeur. Chez les autres fourmis étudiées à titre comparatif, on n'a pas constaté d'agressivité envers les chenilles de Lycénides.

     

Herring bodies; an electron microscopic study of local degeneration and regeneration of neurosecretory axons

Summary The Herring bodies in the posterior lobe of the bovine hypophysis are very large (2–600 ) and can be classified into three types. The type I Herring body contains an accumulation of neurosecretory granules. These Herring bodies are very scarce and should not be confused with the numerous, but small, axonal swellings which also contain neurosecretory granules.The type II Herring body is characterized by the presence of a varying number of normal, moderately electron dense and empty vesicles, autophagic vacuoles, multilamellate bodies and occasional mitochondria. These Herring bodies are frequently observed.The type III Herring body is typified by the presence of dense vesicles connected to tubular formations which contain material of variable electron density, of filaments, and of long slender and very numerous mitochondria.The presence of multilamellate bodies and autophagic vacuoles suggests that the type II Herring body is in a degenerating phase. This concept is further substantiated by the similarity between this type of Herring body and transected neurosecretory axons in which degeneration is occurring.A similar comparison suggests that the type III Herring body is undergoing a regenerative process. Our current concept of the structure and function of Herring bodies is revised in the discussion.This work was supported by grants 5 RO1 NB 06641 NEUA and 5 R0107492 NEUA from the National Institutes of Health and the Space Sciences Research Center of the University of Missouri. The technical assistance of Mrs. G. Clark and Mr. R. Faup, and the clerical assistance of Mrs. S. Schmidt are gratefully acknowledged.Fellow of the Conséjo National de Investigaciones Científicas y Tecnicas de la República Argentína.     

The fine structure of the newborn rat adrenal cortex

Summary The structural changes of the zona juxtamedullaris of the rat adrenal cortex at birth, have been examined by the light and the electron microscope. In this zone clusters of medullary cells lying among the strands of cortical tissue were observed. In the inner portion of the zona juxtamedullaris two types of adrenocortical cells were found: light and very-dark cells. The latter are smaller than the light cells and are always in close connection with the medullary tissue. The ultrastructural features of the very-dark cells suggest that these elements are in degeneration. This finding supports the hypothesis that at birth there is a partial degeneration of the rat zona juxtamedullaris, i.e. the zone corresponding to the fetal zone of some mammalian species.It is proposed that in all mammalian species at birth there is a partial regression of the zona juxtamedullaris and that the regression of the fetal zone is only the quantitative increase of this phenomenon. This hypothesis is discussed in relation to numerous data demonstrating that there are enzymatic conditions in the rat during fetal life, which permit a discrete hypertrophy of the adrenal cortex.The author wishes to express his appreciation to Dr. A. Gambino and to Mr. G. Gottardo for technical assistance.     

Inhibition ofras oncogene: A novel approach to antineoplastic therapy

The most frequently detected oncogene alterations, both in animal and human cancers, are the mutations in the ras oncogene family. These oncogenes are mutated or overexpressed in many human tumors, with a high incidence in tumors of the pancreas, thyroid, colon, lung and certain types of leukemia. Ras is a small guanine nucleotide binding protein that transduces biological information from the cell surface to cytoplasmic components within cells. The signal is transduced to the cell nucleus through second messengers, and it ultimately induces cell division. Oncogenic forms of p21(ras) lead to unregulated, sustained signaling through downstream effectors. The ras family of oncogenes is involved in the development of both primary tumors and metastases making it a good therapeutic target. Several therapeutic approaches to cancer have been developed pointing to reducing the altered gene product or to eliminating its biological function: (1) gene therapy with ribozymes, which are able to break down specific RNA sequences, or with antisense oligonucleotides, (2) immunotherapy through passive or active immunization protocols, and (3) inhibition of p21(ras) farnesylation either by inhibition of farnesyl transferase or synthesis inhibition of farnesyl moieties.     

Rétablissement du cytoplasme et de la force motrice au cours de la restauration de la cyclose chezNitella après irradiation

Résumé En irradiant (500 kR) une fraction seulement du volume cellulaire de la cellule internodale deNitella, il est possible de distinguer au cours des phénomènes de restauration du mouvement cytoplasmique ceux qui dépendent de Pendoplasme (observation de la cyclose dans la zone protégée) et ceux qui dépendent de l'ectoplasme siège de la force motrice (observation de la cyclose dans la zone irradiée).Dans la zone protégée, la vitesse de la fraction endoplasmique irradiée se rétablit en fonction du temps suivant une équation du second ordre. L'augmentation du volume irradié diminue la rapidité du premier des deux processus de restauration et la quantité d'endoplasme qui reste altérée s'accroît.Dans la zone irradiée, le courant cytoplasmique est suspendu; il ne reprend que 4 minutes après le traitement alors que la couche chloroplastique se réorganise. Le glissement des inclusions qu'il charrie se fait un certain temps par saccades. La vitesse de la fraction endoplasmique protégée y augmente régulièrement témoignant ainsi du rétablissement de la force motrice. Le rétablissement a lieu suivant un schéma analogue à celui de Pendoplasme irradié sauf que ce phénomène y est plus rapide et que la force motrice du moins pendant les premières heures se rétablit intégralement. Ces résultats sont discutés (rôle des groupes SH, effet indirect d'empoisonnement, nature des lésions) et comparés à ceux obtenus pour des cellules irradiées in toto.

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Cytoplasm and motive force separated recovery during the re-establishment of the gyclosis in irradiatedNitella cells

Summary In these experiments onNitella internodal cells, only a fraction of the cellular volume is irradiated (by 500 kR). The restoring of the endoplasm (by measurement of the cyclosis in the shielded zone) and the restoring of the ectoplasm where the motive force is generated (by measurement of the cyclosis in the irradiated zone) can be examinated separately during the recovery of the cytoplasmic streaming.In the shielded zone, the plot on a semi-logarithmic scale of a typical rate of streaming-time curve shows that the speed of the irradiated endoplasm. increases again according to a second order equation. With increasing irradiated cellular volume, there are a gradual slowing down of the first processus of restauration and an increase of the definitively altered fraction of the endoplasm.In the irradiated zone, the cytoplasmic streaming stopped completely. About 4 minutes after the treatment, when the chloroplasts layer is reorganising, it exhibits a tendency to flow again. The carried inclusions slide then in jerks during several minutes. The rate of the protected fraction of the endoplasm increases regularly, proving the recovery of the motive force. An analysis of this processus versus time shows that it can be exprimed by a second order equation as that of the irradiated endoplasm. But it is faster and the motive force resumes until full recovery (at least during the first hours).These results are discussed (importance of SH-groups, indirect poisoning effect, kind of lesions) and compared with those observed in completely irradiated cells.

     

Determination of transference numbers from membrane potential data

A system composed of two ionic solutions, solution () and solution (), which are isotonic and separated by a membrane permeable to the solvent and to at most two of the ionic components present in the solutions, is considered. The variations of the difference of electric potential between solution () and solution (), in the steady state and for zero electric current, corresponding to variations in the composition of e.g. solution (), are found to depend only on the properties of the membrane phase at the boundary with solution (). This result is deducible under loose assumptions as to the dependence of the properties of transport and absorption of the permeant components in the membrane on their activities in solution. It can therefore be particularly useful for the study of systems, like biological membranes, whose structural and chemical composition is so poorly known that any assumption about that dependence is hardly justifiable.