Die Bedeutung quergestreifter Faserstrukturen für die Fibrillogenese in der Scheide von Chordomen bei Amphibienbastardlarven

Zusammenfassung In der Scheide von Chordatumoren bei Krötenbastardlarven werden besondere gebÄnderte Fasern mit einer typischen MakroperiodizitÄt von 1100 å dargestellt. Der Vergleich mit Ähnlichen extrazellulÄren Strukturen in normalen und pathologisch verÄnderten Geweben anderer Species macht es wahrscheinlich, da\ es sich hierbei um eine Form des sogenannten fibrous long-spacing collagen (FLS-collagen) oder Tropokollagen handelt. Nach der unterschiedlichen Feinstruktur der hier dargestellten Fasern lassen sich verschiedene Typen unterscheiden, die als transitorische Stufen einer unter dem Tumoreinflu\ vermehrten Fibrillogenese aufgefa\t werden.

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The importance of cross-banded fibers for the fibrillogenesis in the sheath of chordoma of hybrid toad larvae

Summary Special banded fibers with a typical periodicity of 1100 å were found in the sheath of chordoma of hybrid toad larvae. The comparison with analogous extracellular structures in normal and pathological tissues of some other species indicates that the banded fibres are a kind of the fibrous long-spacing collagen (FLS-collagen) or tropocollagen. In respect to the different finestructure of the fibres described here, we can differentiate various types which represent probably different transitional stages of fibrillogenesis increased by the influence of the tumor.

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Der Deutschen Forschungsgemeinschaft sei für ihre materielle Unterstützung, Fr.Beyerle von Wehren für ihre technische Hilfe gedankt.     

Hunting Behavior in the Ctenizidae

The most primitive way of hunting in Mygalomorph spiders seemsto be the free roaming and catching of encountered prey Theraphosidae.The trap-door spiders Ctenizidae, Actinopodidae and Barychelidawhich are entirely sedentary, lie in wait behind the trap-doorand leap at prey that happens to pass close to the door. Somespecies spin radial silk threads outside the door which functionas stumbleor signal-lines, and some Australian species use grassblades and other litter in the same way. A further evolutionarystep leads to species which do not build a trap-door but crowntheir burrow by a funnel-shaped web. The Dipluridae finallyare real web-builders, which depend on a sheet-web to catchtheir prey. Generally they do not dig a burrow but hide in asmall retreat from which a funnel-web leads to the net. With a few exceptions Ctenizidae are entirely nocturnal. Theirrhythm of activity has been analyzed. The "Zeitgeber" is thedaylight during the last half hour before sunset. Most trapdoorspiders never leave their burrow during their whole life. Theyneed three to four years from hatching to become adults. Adultmales die during or at the end of the restricted mating-season;they take no food when adult. Females, which undergo post-adultmolts, can probably live for 15–20 years. Nemesia caementaria, like most other species, hunts during thewhole night. The mean time of activity is about Si/o hours,consisting of periods of lying in wait and periods of intermediaterests. The spiders make an average of three leaps per nightto catch a prey, but only about 10% of all bounds are successful.A hungry animal, lurking in vain, shows unmotivated leaps. The effects of light, moisture, and temperature on hunting activityare analyzed. Ctenizidae hunt during autumn, winter, and springbut interrupt their activity in summer for an estivation whichlasts usually two months. The females of some species capture the male after mating andeat him; others never attack him. This difference in behaviorlias repercussions on reproduction. Among certain species the young nymphs of the third instar refuseall food until they have made their own burrow and can huntby themselves. The young of other species stay with the motherfor one year and leave her at the fifth or sixth instar to maketheir own burrow. The young of Nemesia caementaria can remainin the burrow of the mother until they are almost adult, i.e.,for two or three years, and feed on the prey the mother hascaught. The behavior of Ctenizidae can be grouped. Some species lurkbehind the closed or almost closed trap-door. Another groupopens the trap-door and puts the pedipalpi and the two anteriorpairs of legs radially out onto the rim of the burrow, whilethe cephalothorax is hidden behind the trap-door. A third groupspins threads of silk radially about the entrance and uses themas signal-lines. A fourth group can come out and pursue theprey, then drags it to the trap-door and into the burrow. The nature of the prey depends on the bio tope. The Ctenizidaefeed almost exclusively on insects, mainly ants and beetles;in the laboratory crickets are accepted as prey. Ctenizidae have no tarsal organ. They have different types oftrichobothria, transversal and longitudinal slit-organs, andlyriform organs. With these three kinds of sense-organs, thefunctions of which are not clearly understood, the trap-doorspiders are able to perceive the approach of prey, to judgeits distance from the trap-door, and to locate it in direction.They seem to have an organ of smell, since certain groups ofinsects are repulsive to them. Sight is not used for hunting.     

Nitrogenase activity in extracts of heterocystous and non-heterocystous blue-green algae

Summary Cell-free extracts capable of acetylene reduction and cyanide reduction have been prepared from heterocystous (Anabaena cylindrica) and non-heterocystous (Plectonema boryanum 594) blue-green algae. Extracts from Anabaena were obtained from cultures grown in blulk under aerobic conditions, while the Plectonema cultures were grown in bulk on nitrate-nitrogen, then washed free from nitrate and sparged with A/CO₂ for 40 h after which time maximum nitrogenase activity was detected. The nitrogenases of both algae are similar and resemble in many respects nitrogenases from bacteria and legumes. Activity is located primarily in a 40,000xgx15 min supernatant fraction and the rate of C₂H₂ reduction observed is about 10 per cent of whole cell activity. ATP and a source of reducing power (Na₂S₂O₄) are required for efficient functioning of the enzyme. ATP-dependent hydrogen evolution occurs, the extracts are cold labile and highly sensitive to oxygen and the oxygen inhibition is irreversible.     

Metabolic Studies and Clinical Observations During L-Dopa Treatment of Parkinson's Disease

Twenty-two patients with Parkinson''s disease were treated for the periods of up to six months with L-dopa. In nine of the male patients metabolic observations were made after oral administration of ¹⁴C-L-dopa.Peak serum levels of total radioactivity represented small fractions of the dose given and occurred at one to two hours after ingestion. Two-thirds of the dose was excreted as metabolites in urine in eight hours. Insignificant fractions of the dose were excreted in stool and expired air. These results indicate rapid and complete absorption from the gastrointestinal tract, as well as rapid distribution and excretion. Clinical observations confirmed that L-dopa is an effective treatment for Parkinson''s disease. Improvements in disability averaged 47% at 30 days, 55% at 50 days, and 60% at three months. Degree of improvement tended to be inversely related to age of patient, duration of illness, and severity of disease. Side-effects were seen in most patients, but were always reversible with dose reduction. Nausea was the chief dose-limiting side-effects in early therapy and choreoathetosis after two months of treatment. The average tolerated daily dose was 3 g. On the basis of this experience it seems that the drug can be used safely and effectively on an outpatient basis provided that dosage increments are introduced gradually, maximum dosage is limited to 4 g. a day, and supervision is both close and continuous.