Nervous and behavioral responses to light in colonies of the free-living bryozoan,Selenaria maculata (Busk)

Summary Bursts of electrical impulses which spread throughout the entire colony were recorded from individual zooids ofSelenaria. Strong illumination caused a rapid increase in the frequency of bursts and also caused the colonies to start moving, usually towards the light the recorded electrical activity may act to trigger locomotor behavior.We are grateful to Dr P. Arnold (James Cook University, Townsville) for his assistance in collecting the live material ofS. maculata, to Miss P. L. Cook and Mr P. J. Chimonides (British Museum (Natural History) for their helpful discussions, and to Dr J.P. Thorpe (University of Liverpool) for suggesting the topic. We thank also the Science and Engineering Research Council for financial support (grant No. GR/A71578).     

Identification of precoccinellin in the ladybird beetle,Coleomegilla maculata

Zusammenfassung Isolierung und Strukturzuteilung für ein Alkaloid ausColeomegilla maculata (Coleoptera: Curculionidae).

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Coleoptera: Curculionidae.

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In cooperation with the Mississippi Agricultural and Forestry Experiment Station, Mississippi State, Mississippi 39762. Received for publication.

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Mention of a proprietary product does not necessarily imply endorsement of this product by the USDA.     

A new pattern of hermaphroditism (inducible hermaphroditism) in populations ofOphryotrocha labronica (Annelida Polychaeta)

Summary A new kind of hermaphroditism, which is called inducible hermaphroditism, has been discovered in the otherwise gonochoristic populations ofOphryotrocha labronica of the Gulf of Naples and of the Lagune of Venice. Inducible hermaphrodites, which are fertile in both the male and female phases, represent 25.8% and 31.8% of the Naples and Venice strains respectively. Inducible hermaphrodites are obtained when pairs between adult females — or female phase hermaphrodites — and juveniles are formed. Crosses between inducible hermaphrodites, in different sex phases, pure male and female individuals give progenies whose sex ratios are clearly correlated with the sex genotypes of the parents.     

A reticulum of nerve-like cells from trochophores of Phyllodoce mucosa (Polychaeta)

Summary The positions of and connections between the 12 principal cells of the larval reticulum are described from Golgi-Cox preparations and sections.Supported by the National Research Council of Canada and carried out in part at the Huntsman Marine Laboratory, St. Andrews, N.B.     

Environmental and racial influences on the masticatory apparatus of mediterranean and atlantic populations ofOphryotrocha labronica (Annelida,Polychaeta)

Summary Significant differences in the length of the definitive upper jaw have been ascertained in 3 populations of the comprehensive speciesO. labronica. The ratio of the variance (F) of the 3 populations has been employed in evaluating the taxonomic distance between the populations. The density of the water and the kind of food strongly influence the length of the definitive upper jaw.     

Observations on the ultrastructure of the non-articulated laticifers ofJatropha podagrica (Euphorbiaceae)

Zusammenfassung Einleitende elektronenmikroskopische Untersuchungen der ungegliederten Milchröhren vonJatropha-podagrica-Embryonen haben das Vorkommen von Verbindungen der Zellkerne, augenfälligen Dictyosomen und reichliche Mengen von Mikrotubuli in diesen aussergewöhnlichen Zellen gezeigt. In den Milchröhren dieser Art wurde kein Vorkommen von Zellverschmelzung beobachtet.

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This research was supported by U.S.P.H.S. Postdoctoral Fellowship No. 5-F2-GM-33, 474-02.     

Role of calcium in the reinitiation of oocyte meiosis in Sabellaria alveolata (L.) (Annelida, Polychaeta)]

Meiotic maturation is triggered by ionophores A 23187 and X 537 A, even in absence of extracellular calcium. CaMg free medium alone initiates 100% maturations while Ca free SW triggers varying percentages of maturation and Mg free SW has no effect.     

Electrophoresis of proteins in three populations ofOphryotrocha labronica La Greca e Bacci 1962 (Annelida Polychaeta)

Summary Different degrees of similarity are found between the electrophoretic patterns of proteins ofOphryotrocha labronica populations collected in 3 different localities.     

The ultrastructure of thiosomes of the mouse brain

Zusammenfassung Nachweis, dass die chromhämatoxylinen, Gomori-positiven Granula in periventrikulären Gliazellen des Säugetiergehirns grosse Organellen mit hohem Schwefelgehalt (Thiosomen) und charakteristischer lamellärer Binnenstruktur darstellen.

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Acknowledgments. I thank Mr.J. Godula, M. Sc., for excellent technical asistance.     

The ultrastructure of a cyclostome interrenal

Résumé Après un exame au microscope électronique, le tissue interrénale de la lamproie,Lampreta planeri, montre tous les caractères essentiels d'un tissue stéroïdogénique, soit un reticulum lisse abondant, la présence de liposomes, de vésicules cytoplasmique très nombreuses et de mitochondries à crêtes tubulaires ou vésiculaires. Ces observations confirment l'idée que ces cellules correspondent au tissu interrénal ou adrénocortical des autres vertébrés.

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This investigation has been supported by financial assistance from the Science Research Council.     

Simple procedure to isolate coelomocyte-free oocytes from coelomic fluid ofPerinereis cultrifera Grübe (Annelida; Polychaeta)

Summary Based on a l-g sedimentation through a Ficoll cushion, a simple and rapid method is described to obtain the complete separation of oocytes and coelomocytes from the coelomic fluid ofPerinereis cultrifera. Light and electron microscope observations have shown that the 2 cell populations are obtained without any cross-contamination and are perfectly suitable for further biological and biochemical investigations.