On the relative importance of juvenile hormone and vitellogenin for oöcyte growth in the cockroach Nauphoeta cinerea

The corpora allata of castrated females of Nauphoeta grow only very slightly and do not reach a volume greater than that of the glands of normal females during gestation. These small corpora allata are, however, active and are responsible for the synthesis of vitellogenin (female specific protein) in large amounts. Besides vitellogenin the other haemolymph proteins are also synthesized and accumulated in the haemolymph in much higher concentrations than in normal females. Implanted oöcytes grow in castrated as well as in normal females at about the same rate until the tenth day of the oöcyte maturation period. Thereafter they only grow in castrated females. If castrated and normal females are decapitated, their protein content decreases. At the same time the growth stimulating capacity of their haemolymph decreases at a much faster rate. If oöcytes are implanted in castrated and decapitated females after 4 days they cannot grow any more although the vitellogenin titre of the haemolymph is still much higher than it is at any time in normal females. It can be concluded that vitellogenin alone cannot induce oöcyte growth and that juvenile hormone is necessary as well for vitellogenin synthesis as for its incorporation into the oöcytes. However, in insects rich in vitellogenin juvenile hormone leads to a more rapid oöcyte growth than in insects containing only small amounts of this protein.     

Struktur und chemische asymmetrie von nierenmembranen

Zusammenfassung Die elektronenmikroskopische Untersuchung einiger Membranfraktionen des äußeren Cortex der Säugerniere, welche in Anlehnung an Post und Sen (1967), z.T. mittels Zentrifugation im Rohrzuckerdichtegradienten, gewonnen wurden, hat große Inhomogenität der Präparationen aufgezeigt, sowohl hinsichtlich der Art der Strukturelemente als auch der Größe der Membranfragmente. Die isolierten Membranen bilden meist geschlossene Vesikel. Eine Ausnahme stellt die im Zuckergradienten bei d = 1,1 sich anreichernde Fraktion dar. Sie besteht vorwiegend aus 0,1–0,5 großen Membranvesikeln und offenen Membranfragmenten, bei denen es sich sehr wahrscheinlich um Fragmente der Bürstensäume handelt.Markierungsexperimente mit dem SH-Reagens Hg-Phenyl-Azoferritin haben ergeben, daß die isolierten Membranen ebenso wie diejenigen inkubierter Kryostatschnitte Hg-Ferritin ausschließlich auf der cytoplasmatischen Seite binden. Bezüglich der Besetzungsdichte verhalten sich die Nierenmembranen jedoch inhomogen: Während die Membranen der Mikrovilli und Lysosomen praktisch keinerlei Ferritinanlagerung zeigen, sind die Mitochondrienmembranen dicht markiert. Bei den Membranen des basalen Labyrinths findet man neben einzelnen dicht besetzten Ferritininseln weite Membranabschnitte ohne Hg-Ferritin. Daß das Hg-Ferritin mit den Thiolgruppen der Membranen reagiert, beweist die starke Verringerung der Ferritinbindung nach NEM-Vergiftung der Membranen sowie die unverminderte Anlagerung nach NEM-Behandlung in Gegenwart von ATP, welches die SH-Gruppen in den Membranen vor der Blockierung durch NEM schützt.Werden die Phospholipide mit Phospholipase A und Albumin aus den Membranen entfernt, so ändern sich weder die Morphologie der charakteristischen Strukturelemente der Nierenmembranen noch ihr polares Reaktionsvermögen mit Hg-Ferritin wesentlich.

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Structure and chemical asymmetry of kidney membranesElectron microscopic investigations on different membrane fractions of the outer cortex of mammalian kidney

The electron microscopic investigation of several membrane fractions of the outer cortex of mammalian kidney (pig) isolated according to Post and Sen (1967) and by sucrose gradient centrifugation has revealed great inhomogeneity with regard to the kind of the structural elements as well as to the size of the membrane fragments. The isolated membranes mostly form closed vesicles. As an exception a relatively homogeneous fraction bands at a density of d = 1.1. It consists mainly of membrane vesicles and fragments of a diameter of 0.1–0.5 , which most probably are fragments of the brush borders.Labeling experiments with the SH-reagent Hg-phenyl-azoferritin show that the isolated membranes as well as those of the incubated cryostate sections bind Hg-ferritin exclusively at the cytoplasmic surface. As to the density of the ferritin-labeling: while membranes of the microvilli are practically free of ferritin, the mitochondrial membranes are densely labeled. The membranes of the basal labyrinth exhibit small areas closely packed with ferritin as well as long segments free of ferritin. The thiol-group labeling by Hg-ferritin is proved by the decrease in binding after NEM-poisoning of the membranes as well as by the undiminished attachment after NEM-treatment in the presence of ATP, which protects the SH-groups in the membranes from being blocked by NEM.When the phospholipids are extracted from the membranes with phospholipase A and albumen, neither the morphology of the characteristic structural elements of the kidney membranes nor their polar reaction with Hg-ferritin are changed markedly.

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Fräulein Heidi Behre danken wir für sorgfältige Hilfe bei der Durchführung der Untersuchungen.     

Growth of Rio Bravo Virus in Cell Cultures

The growth of Rio Bravo virus (RBV) in eight cell culture systems was studied. Highest yields of virus were produced in BHK-21 (C13), L, and Vero cell lines, but L cells were resistant to low doses of virus. LLC-MK(2), HeLa, and human embryo skin cells produced moderate amounts of virus, but FL amnion and primary chick embryo fibroblasts supported little virus growth. Virus was rapidly inactivated by exposure to pH values below 7.0. Single-cycle growth in BHK-21, L, and LLC-MK(2) cell monolayers was characterized by a latent period of about 12 hr followed by rapid virus production that peaked at 36 to 48 hr. Vero cell cultures can remain chronically infected with RBV for more than 100 days. Such cultures show evidence of cell destruction, and their supernatant fluids contain virus at 10(4) to 10(5) log(10) per ml.     

Temporal nitric oxide dynamics in the paranasal sinuses during humming.

In this study, the temporal shape of voice-induced nitric oxide (NO) signals in exhaled air has been investigated in eight healthy individuals by means of laser magnetic resonance spectroscopy. The results of the experimental part have been compared with calculated signals obtained by using a simple one-compartment model of the paranasal sinuses. In the experimental part, a rapidly increasing NO concentration has been found when the subjects started humming. After reaching a maximum, the emission starts to decrease with the shape of an exponential decay and finally reaches a constant level. The time constant of this decay (NO washout) is 3.0 +/- 1.2 s. The peak height of the NO emission during humming increases when the time between two humming processes increases. When no voice-induced NO emission takes place, the NO concentration in the paranasal sinuses rebuilds again to a maximum concentration. The typical time constant for the NO recovery is 4.5 +/- 3.2 min. A three-compartment model defining exactly the geometry and anatomy of the paranasal sinuses has been developed that is based on three main assumptions of the NO dynamics: 1) constant NO production of the epithelium in the sinuses; 2) the rate of the chemical reaction of NO with the epithelium of the paranasal sinuses is proportional to the NO concentration; and 3) the emission of NO from the sinuses (volume/s) is proportional to the NO concentration. It is shown that the three-compartment model under the experimental conditions can be reduced to a one-compartment model, which describes the complete temporal behavior of the NO exchange.     

Evaluation of quantitative anti-F1 IgG and anti-V IgG ELISAs for use as an in vitro-based potency assay of plague vaccine in mice.

Quantitative anti-F1 and anti-V IgG enzyme-linked immunosorbent assays (ELISAs) were developed to measure the serological response of female Swiss Webster mice after vaccination with the recombinant fusion protein, rF1-V, which is being developed as a plague vaccine. Several fundamental parameters of the ELISA were evaluated: specificity, precision, accuracy, and stability. Experimental results suggested that a potency assay based upon the serological response of female Swiss Webster mice, as measured by quantitative anti-F1 IgG and anti-V IgG ELISAs, might be used to evaluate the rF1-V fusion protein vaccine.     

ISOLATION OF A NON‐PHAGE‐LIKE LYTIC VIRUS INFECTING AUREOCOCCUS ANOPHAGEFFERENS1

We have been working to characterize viruses that infect the HAB‐forming pelagophyte Aureococcus anophagefferens Hargraves et Sieburth. Field samples were collected during brown‐tide events in 2002 and tested for the presence of lytic agents. Here, we describe a recently isolated, lytic virus‐like particle (VLP) that is morphologically similar to particles observed in thin sections of infected A. anophagefferens cells from natural samples. TEM and SEM have revealed VLPs consistent with the morphological characteristics of previously described Phycodnaviridae. Large icosahedral particles (～140 nm) of similar shape and morphology dominate cell lysates and are accompanied by smaller phage‐like particles and heterotrophic prokaryotes that appear to be incurable from our cultures. To determine which of these particles interacts with the Aureococcus cells, we preserved cultures during the early stage of infection so that SEM could be used to visualize those particles that attach to the surface of naïve cultures. SEM revealed that 63% of the large icosahedral‐shaped particles attached to A. anophagefferens cells after only 30 min of exposure, while no significant frequency of attachment to the alga was observed for the phage‐like particles. The results of these observations are in contrast to previous studies, where phage‐like particles were reported to infect cells. When considered in conjunction with field observations, the results suggest that this newly isolated virus represents the dominant virus‐morphotype associated with bloom collapse and termination.