Morphogenesis of Newcastle Disease Virus in Chorioallantoic Membrane

Chick embryo chorioallantoic membrane, infected with the Blacksburg strain of Newcastle disease virus, was examined with an electron microscope to investigate the sequence of viral-induced host cell alterations. These were evident mostly in the endodermal epithelial cells lining the allantoic sac and were divided arbitrarily into three stages. Stage 1 was characterized by commencement of cell hypertrophy and hyperplasia and presence of fewer cytoplasmic inclusion bodies normally found in the cells; in stage 2, juxtanuclear nucleocapsid-glycogen aggregates appeared, and there were increased numbers of microvilli; stage 3 was characterized by increased cytoplasmic density and evidence of viral assembly and release. The morphological features of viral assembly and the virion are also described.     

The Occurence of δ-Tocopherylquinone in Higher Plants and Its Relation to Senescence

δ-Tocopherylquinone (δTQ) content was determined in tobacco and yellow maple leaves, green ivy leaves and cactus tissues. It was found that the concentration of δ-TQ was highest in mature or senescent tissues, such as white tobacco leaves (0.02 μmole/g dry wt) while its detection was uncertain in young, green leaves from the apex of tobacco plants. Fractionation by centrifugation of senescent tobacco leaves showed that the osmiophilic globule fraction was enriched in δ-TQ. Electron microscope studies of young, mature and senescent tobacco tissues showed progressive changes in the size and number of osmiophilic globules. After chloroplast breakdown in senescent tobacco leaves, these globules became the predominant constituents of the organelle. δ-TQ which is associated with osmiophilic globules may play a role in the development of plants, particularly during senescence.     

Wirtskreis und Infektionscyclus eines neu isolierten Bdellovibrio bacteriovorus-Stammes

Zusammenfassung Der neu isolierte Stamm W von Bdellovibio bacteriovorus infiziert und lysiert Rhodospirillum rubrum F und alle anderen untersuchten Athiorhodaceae, nicht aber Pseudomonas aeruginosa und Spirillum serpens. Er befällt auch zahlreiche Enterobacteriaceae und von den grampositiven Bakterien Streptococcus faecalis und Lactobacillus plantarum.Nach dem Festheften an der Zellwand wird diese in 3–20 min durchdrungen. In 10–60 min ist Bdellovibrio vollständig in die Zelle eingedrungen und hat sich im Raum zwischen Zellwand und cytoplasmatischer Membran angesiedelt.In 3–5 Std wird der gesamte Zellinhalt bis auf die Membranen aufgelöst. In dieser Phase erfolgt die Vermehrung von Bdellovibrio. In den ghosts sind die Parasiten in lebhafter Bewegung. Die Geißel hat einen Gesamtdurchmesser von 29 m und eine Länge von etwa 3 . Sie ist von einer Geißelscheide umgeben, die in Verbindung zur Zellwand steht. Der Durchmesser der Geißel ohne Scheide beträgt etwa 18 m. Bdellovibrio kann oberhalb eines Sauerstoffpartialdruckes von 4–5 mm Hg infizieren und sich vermehren. Der Titer von Bdellovibrio nimmt bei Aufbewahrung in lysierten Kulturen in 36 Tagen von 10⁸ auf 10¹ pfu (plaque forming units) je ml ab. Bei Aufbewahrung in Nährkultur sinkt der Titer nur auf 10⁴ pfu/ml ab. Die Zahl der Plaques im Verhältnis zum Titer der Impfsuspension von Bdellovibrio schwankt in Abhängigkeit vom Wirtsstamm. Wenn man die Plaque-Bildungsrate bei R. rubrum gleich 1 setzt, beträgt sie bei Serratia marcescens 0,0001, bei Proteus vulgaris 10. Bd. bacteriovorus, Stamm W wächst nicht in synthetischer Nährlösung oder Lysaten. Ein geringes Wachstum ohne Zellteilung findet in Zellextrakten von R. rubrum statt. Der Stamm vermehrt sich jedoch in hitzeinaktiviertem R. rubrum. Die Plaque-Bildungsrate ist unter diesen Bedingungen aber sehr niedrig.In Lysaten treten encystierte Dauerformen von Bdellovibrio bacteriovorus auf.

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The host range and the infectious cycle of a new isolated, on gram-positive and gram-negative bacteria parasiting Bdellovibrio bacteriovorus strain

Summary Rhodospirillum rubrum and all other investigated Athiorhodaceae are infected and lysed by the new isolated strain W of Bdellovibrio bacteriovorus. This strain W parasites on numerous Enterobacteriaceae and the gram-positive bacteria Streptococcus faecalis and Lactobacillus plantarum, but not on Pseudomonas aeruginosa and Spirillum serpens.After attachment of Bdellovibrio to the host, the cell wall is penetrated in 3 to 20 min. In 10 to 60 min Bdellovibrio has completely entered the host cell. He remains in the space between cell wall and cytoplasmic membrane of the host.The host cell is completely lysed within 3 to 5 hours. During this phase the size and cell number of Bdellovibrio are increased and a new flagellum is likely to be formed. In the ghosts of the host cell a strong movement is observed. The single polar flagellum of Bdellovibrio has a diameter of 29 m. The flagellum consists of an inner core ( 18 m) and an outer sheath which is continued into the cell wall. Bdellovibrio is able to grow and to infect only under aerobic or semiaerobic conditions (oxygen partial pressure 4 to 5 mm Hg and more). The titer of Bdellovibrio is gradually decreased from 10⁸ to 10¹ plaque forming units (pfu) per ml, when kept in the lysate for 36 days. In a synthetic medium there is a diminution of 10⁴ pfu/ml only. The plating efficiency is dependent of the host strain. If the plating efficiency of Bdellovibrio with Rhodospirillum rubrum is 1.0, the rate varies from 0.0001 with Serratia marcescens to 10 with Proteus vulgaris. Bdellovibrio bacteriovorus strain W does not grow in a synthetic medium. However, it grows but does not multiply in cell free extracts of Rhodospirillum rubrum. The parasite is also able to infect and lyse heat inactivated R. rubrum. But the plating efficiency in this case is very low.It has been observed that in lysed cells of R. rubrum certain amount of Bdellovibrio is encysted. The morphology and fine structure of these cells is quite different from the normal virulent type.