Occurrence of virus-like particles in cultured cloudman S-91 melanoma

Zusammenfassung Elektronenmikroskopische Untersuchungen des Cloudman-S-91-Melanomagewebes ergaben das Vorhandensein virusähnlicher Teile in der Kultur, die sich strukturell nicht unterscheiden lassen von den in Mäuse-Mammatumoren beobachteten. Die inneren und äusseren Gewebsteilchen waren morphologisch mit verschiedenen Mäuseneoplasmen vergleichbar.

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This investigation was supported by research grants C-5884 and C-5585 from the National Institute of Health, Public Health Service.     

Fractions of calving interval and reproductive efficiency in italian friesian cows

Riassunto In relazione alle frazioni dell'intervallo interparto è stata studiata l'efficienza riproduttiva nelle vacche (445 soggetti) di razza Frisona italiana, allevate in una grande azienda del Salernitano (Italia), come numero di inseminazioni per concepimento, come percentuale degli aborti sul totale di essi e sui concepimenti, e come lunghezza del periodo dal concepimento all'aborto.     

Ring-canals and intercellular communication within the egg-chamber of a tsetse fly species

Zusammenfassung In der Ovariole der Tsetsefliege werden 15 Trophozyten und eine Oozyte festgestellt, die in wohlgeordneter Weise durch 15 Ringbildungen miteinander verbunden sind. Eine Anordnung, welche die Rekonstruktion der vorausgegangenen Mitosen dieser 16 Zellen möglich macht.

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This work was supported by a grant from the Rockefeller Foundation. I wish to thank Mrs. D.McLachlan and Mr.P. Lisamulla for technical assistance and the East African Trypanosomiasis Research Organization, Tororo, for the provision of tsetse flies.     

Mycoplasma-like organisms in histological sections of infected sandal spike (Santalum album L.)

Résumé Une méthode simple est décrite pour l'étude radioscopique des tissus du bois de Santal (Santalum album L.) infectés par un organisme du type dit mycoplasme. Les techniques comprennent au préalable l'emploi de colorants Giemsa et Dienes, précédant l'étude microscopique. Des organismes du type dit mycoplasme et (ou) des inclusions cytoplasmiques d'origne mycoplasmique ont été localisées dans les tissues contaminés du bois de Santal, surtout dans les régions du xylème et du phloème.     

Effets de la 2-mercaptopropionyl-glycine sur la différenciation de l'œuf d'oursin

Summary 2-Mercaptopropionyl-glycine (Thiola) exerted a strong animalizing action on the development of the sea urchin,Paracentrotus lividus. The action of Thiola on the synthesis of superficial and cortical cellular structures newly synthesized during the segmentation is suggested. These changes may alter the circulation of morphogenetic substances between blastomeres.     

Statistical tests on two characteristics of the shapes of cluster diagrams

A cluster diagram is a rooted planar tree that depicts the hierarchical agglomeration of objects into groups of increasing size. On the null hypothesis that at each stage of the clustering procedure all possible joins are equally probable, we derive the probability distributions for two properties of these diagrams: (1)S, the number of single objects previously ungrouped that are joined in the final stages of clustering, and (2)m _k, the number of groups ofk+1 objects that are formed during the process. Ecological applications of statistical tests for these properties are described and illustrated with data from weed communities of Saskatchewan fields.This work was supported by the Natural Sciences and Engineering Research Council of Canada.