Effects of Oleate Starvation in a Fatty Acid Auxotroph of Escherichia coli K-12

The effects of oleate starvation on an oleate auxotroph of Escherichia coli K-12 were investigated. Following removal of oleate from the mutant growing in a minimal glycerol-peptone medium, the cells stopped making deoxyribonucleic acid, ribonucleic acid, protein, and phospholipids; they began to die exponentially and finally lysed. During oleate starvation in minimal medium minus peptone, inhibition of macromolecular syntheses and death occurred; however, lysis did not follow. When growth ceased, no further dying was observed. It is shown that none of the early effects (inhibition of macromolecular syntheses and death) can be due to leakiness of the cells, induction of a prophage or a colicin, or lack of energy sources. The cause of inhibition of macromolecular syntheses remained unknown. Since the rate of death was the same as the generation time under different conditions, it appears that death is due to the defective synthesis of some cellular structure (quite possibly, cytoplasmic membrane) during phospholipid deficiency. Lysis was found to require protein synthesis; electron microscopy revealed a peculiar type of "lysis from within"; i.e., the shape of the cells did not change but fragmentation of the inner layer of the cell envelope occurred. The murein was found to be unaltered. Most likely, lysis was a consequence of the cell's attempt to synthesize cytoplasmic membrane with altered phospholipid composition or during phospholipid deficiency. Several membrane functions (respiration, adenosine triphosphate formation, permeability) existing before oleate removal were not lost during starvation. Therefore, general damage to the membrane did not occur, and it could be that most, if not all, described effects were due to defective de novo membrane synthesis.     

Occurrence of two l-threonine (l-serine) dehydratases in the thermophile Chloroflexus aurantiacus

The thermophilic phototrophic prokaryote, Chloroflexus aurantiacus was shown to contain high constitutive l-threonine (l-serine) deaminating activity. Separation of cellular proteins by DE 52-cellulose chromatography and by polyacrylamide gel electrophoresis with subsequent activity staining of the gels yielded two bands, one representing an isoleucine-sensitive, the other one an isoleucine-insensitive form of l-threonine dehydratase. Both enzymes had a molecular weight of 120,000 but were distinguished by their different affinities to the two substrates, l-threonine and l-serine.Abbreviations SDH l-serine dehydratase - TDH l-threonine dehydratase     

NADH-dependent glutamate synthase and nitrogen metabolism in Neurospora crassa

The GDH (NADPH) mutant strain $\text{am-1}$ of $\text{N. crassa}$ has sizable pools of glutamine and glutamate under ammonium-limited conditions for which requires an elevated glutamine synthetase activity. Glutamine in the pre$\text{s}$ ence of 2-oxoglutarate, stimulated nicotinamide nucleotide oxidation by crude and purified extracts of the $\text{am-1}$ strain and led to a reductant dependent formation of two molecules of glutamate. Aminooxyacetate did not have any effect on the reaction, whereas azaserine inhibited it completely. It is concluded that in $\text{N. crassa}$ glutamine synthetase and glutamate synthase are responsible for the assimilation of low ammonium concentrations.     

Social influences on first reproductive success and related behaviors in the saddle-back tamarin (Saguinus fuscicollis,callitrichidae)

Some aspects of sociosexual behavior and the age at which maturing females experienced their first evident pregnancy and at which maturing males caused their first evident pregnancy were recorded in Saguinus fuscicolliscohabiting from 6 months of age with either an adult or a maturing sex partner. The following pair combinations and trios were studied: young male -young female, young male-adult female, adult male-young female, and adult male-young male-young female. The most frequent type of social interaction between young animals was rough and tumble play, while huddling was the most frequent interaction between young animals and their adult partners. Grooming and sexual interactions were very infrequent and there were no differences in the frequencies of these interactions among subject groups. Maturing females cohabiting with an adult male conceived significantly earlier than maturing females cohabiting with a male of their own age. Maturing males cohabiting with adult females sired offspring at a significantly earlier age than males cohabiting with a female of their own age. Some possible behavioral and physiological processes involved in the causation of early reproductive success in young tamarins cohabiting with adults are discussed. Saguinus fuscicollis fuscicollis andSaguinus fuscicollis illigeri.     

Lichtinduzierte Farbstoffbildung bei Saccharomyces cerevisiae var. ellipsoideus

Zusammenfassung Die lichtinduzierte Pigmentbildung wird in Abhängigkeit von verschiedenen Faktoren untersucht und ihre Kinetik gemessen. Der Farbstoff entsteht nur in einem stickstoffhaltigen Medium. — Der Temperaturbereich, innerhalb dessen Pigmentbildung möglich ist, liegt zwischen 14° und 39° C mit einem Optimum bie 29° C. — Für die Anfangskonzentration von Glucose im Medium wird ein Optimum bei 3% gefunden. Nach Verbrauch der Glucose hört die Farbstoffbildung auf, sofern nicht ein anderer Faktor begrenzend wirkt wie z. B. hohe Lichtintensität, durch die die Pigmentproduktion stark eingeschränkt, schließlich sogar völlig verhindert wird. In Abhängigkeit von der Lichtintensität findet sich ein Optimum der Pigmentbildung je nach Lichtsensibilität der Zellen zwischen 26 und 45 kerg · sec^-1 · cm^-2. Hohe Lichtintensität wirkt zerstörend auf bereits entstandenes Pigment. — Die Aktivität des pigmentbildenden Systems sowie die erreichbare Farbstoffendkonzentration hängen ferner vom Beginn der Belichtung ab. Nennenswerte Pigmentsynthese ist nur möglich bei einem Belichtungsbeginn innerhalb der ersten 10–12 Std und ist um so intensiver, je früher die Belichtung einsetzt. — Bei im übrigen günstigen Kulturbedingungen arbeitet das pigmentbildende System nur während der Lichteinwirkung. — Kinetische Untersuchungen der Farbstoffbildung zeigen, daß das Pigment im Medium entsteht und von dort in die Zellen aufgenommen wird. Demnach muß eine Synthese von Pigmentvorstufen in den Zellen und ihre Abgabe an das Medium angenommen werden.

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Light-induced pigment production by Saccharomyces cerevisiae var. ellipsoideus Physiology of pigment production

Summary Light-induced pigment synthesis by cells of Saccharomyces cerevisiae var. ellipsoideus is investigated under the influence of various factors, and kinetic studies of its formation are performed. Pigmentation only occurs with nitrogen in the medium. The temperature favouring pigment production ranges between 14° C and 39° C, and has its optimum at 29° C. Optimum glucose concentration in the medium is 3%. Pigment formation continues until glucose is completely exhausted provided that no other factor — as for instance high light intensity — limits pigment synthesis before. The lowest possible light intensity for pigment production was found at 3 kerg · sec^-1 · cm^-2, the optimum lies between 26 and 45 kerg ¢ sec^-1 · cm^-2 — depending on the light sensibility of the cells. Still higher light intensities finally destroy part of the pigment already formed. — There is a clear influence of the onset of light exposure a) on the activity of the pigment producing system and b) on the end concentration of pigment. Only cells exposed to light within the first 10–12 hours of culture give rise to considerable pigment synthesis which is the more active the more the onset of light approaches that of the culture. If all other factors are favourable the pigment producing system once working continues to do so only as long as light is on. —Kinetic experiments show the pigment to be formed in the medium and then to be incorporated by the cells. It must be concluded therefore that pigment precursors are synthesised in the cell and from there transferred into the medium.

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Herrn Prof. Dr. W. Simonis zum 60. Geburtstag gewidmet.     

Elektronenmikroskopische Untersuchungen am Pinealorgan von Pterophyllum scalare Cuv. et Val. (Cichlidae,Teleostei)

Zusammenfassung Das Pinealorgan (Epiphysis cerebri) des Knochenfisches Pterophyllum scalare besteht aus nervösen und gliösen Zellelementen. Sehr stark ausgebildet sind die ependymalen Stützzellen. Sie umhüllen mit ihren Ausläufern, die sich überlappen können, andere Zellelemente, z.B. Rezeptorzellen und marklose Nervenfasern. Neben dieser Neuroglia-Art finden sich auch noch oligodendrocytenähnliche Gliazellen. In ihrer Grundstruktur entsprechen die Rezeptoren den Epiphysensinneszellen anderer Knochenfische. Vom cilientragenden Teil des Außenglieds geht ein schürzenartiger Lamellenstapel aus. Dieser besteht aus 50–70 Lamellenplatten von etwa 6 m Länge. Im basalen Teil der Rezeptorzelle sind neben schlanken Mitochondrien mit unregelmäßigen Cristae und Tubuli auch noch große, runde Mitochondrien mit einer regelmäßigen Cristastruktur zu beobachten. Der basale Fortsatz der Rezeptorzelle ist auf die axial verlaufenden Axonbündel ausgerichtet. Synapsenartige Kontakte sind selten. Die Zahl der marklosen Axone nimmt hirnwärts zu; dieser Befund wurde in partiellen Rekonstruktionen gesichert. Am Übergang in den Epiphysenstiel treten einige markhaltige Axone auf. Zur Verteilung der Zelltypen und zum Verlauf der Axonbündel im Epiphysenstiel des Skalars liegen detailliertere Angaben vor als bei anderen bisher untersuchten Knochenfischepiphysen. In der Diskussion werden nach Vergleich der pinealen Rezeptoren verschiedener Fische drei Außengliedformen unterschieden: Bürsten-, Schürzen- und Kappentyp. Diese Varianten werden in Verbindung mit den bekannten physiologischen Reaktionsformen der Pinealorgane diskutiert. Die elektrophysio logischen Unterschiede lassen sich nicht mit verschiedenen Strukturtypen des Außenglieds erklären.

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Electron microscopic studies of the pineal organ in Pterophyllum scalare cuv. et val. (Cichlidae, Teleostei)

Summary The pineal organ (epiphysis cerebri) of Pterophyllum scalare is formed by neuronal and glial elements. Ependymal supportive cells are very abundant, and their cytoplasmic processes envelop adjacent receptor cells and unmyelinated nerve fibers by an intertwining network. In addition to this type of neuroglia, oligodendrocytic cells have also been identified. The receptor cells show the general structural pattern (outer segment, inner segment, basal process) of teleostean pineal receptors. The ciliary part of the outer segment bears a dome-like stack of 50–70 curved saccules each of average length of 6 m. In the basal part of the receptor cell, slender mitochondria containing irregular cristae and tubules, and also some more spherical mitochondria with a highly regular arrangement of cristae, can be observed. The basal cytoplasmic process radiates into neuropile-like areas that contain axial bundles of axons. Synaptoid contacts rarely occur. The number of unmyelinated axons of the pineal stalk, increases in a proximad direction (towards the brain). This finding has been verified in partial reconstructions. In the transitional zone leading from the pineal body into the pineal stalk, a few myelinated fibers become visible. With respect to cell types and the axonic bundles of the pineal stalk in Pterophyllum scalare, more detailed data are presented than for most other teleostean pineal organs examined thus far. The comparison of pineal sensory cells in several fishes allows a distinction among three different types of outer segments, i.e., a slender type, a dome-like type, and a cap-like type. These structural types are discussed with respect to the relevant physiological results. The existence of particular structural types of the outer segment does not explain the different electrophysiological reactions observed in different pineal organs.

Ein Druckkostenzuschuß wurde von beiden Instituten zur Verfügung gestellt.     

Kurze Mitteilungen

Ohne Zusammenfassung     

Lichtmikroskopische und elektronenoptische Untersuchungen über den Aufbau pflanzlicher Chromosomen im Pachytän der Meiosis

Ohne ZusammenfassungTeil einer Dissertation der Naturwiss.-mathem. Fakultät der Universität Freiburg i. Br.Herrn Professor Dr. Dr. H. Marquardt danke ich sehr für die Überlassung des Themas und für sein stetes Interesse, ebenso Herrn Dr. W. Liese für die Einführung in die Technik der Elektronenmikroskopie.     

Cloning and Physical Mapping of an Early Region of the Bacteriophage T4 Genome

We have cloned DNA restriction fragments from the largely nonessential region of bacteriophage T4 located between genes 39 and 56. The cloned DNA fragments were used to construct a precise map of the sites in this region recognized by eight restriction endonucleases. This restriction map allowed us to compare the cytosine-containing T4 DNA used for cloning with the hydroxymethylcytosine-containing DNA of wild-type T4; there were no detectable rearrangements in the region tested. We were also able to determine the physical locations of several deletion end points and of several genes.