Zum Ortungsverfahren von Gyrinus substriatus Steph

Zusammenfassung Die vorliegende Arbeit befaßt sich mit dem Orientierungsvermögen des Taumelkäfers (Gyrinus substriatus) im Bereich der Wasseroberfläche mit Hilfe der Antennenorgane.Der Taumelkäfer besitzt eine hohe Empfindlichkeit gegenüber Oberflächenwellen und ist in der Lage, deren Einfallsrichtung festzustellen. Im Nahbereich werden Hindernisse, die in die Wasserfläche eintauchen und einen Meniskus hochziehen, gut erkannt.Die mechanischen und elektrophysiologisohen Eigenschaften der Antennen werden ermittelt. Mechanische Erschütterungen rufen Relativbewegungen zwischen Pedicellus und dem frei in die Luft ragenden Flagellum hervor und erregen das Johnstonsehe Organ. Pedicellus und Flagellum sind als schwingungsfähiges System anzusehen, dessen Eigenfrequenz 250 Hz beträgt und dessen relatives Dämpfungsmaß etwa den Wert 0,7 hat. In dem in Frage kommenden Frequenzbereich bis 150 Hz arbeitet das Schwingungssystem vorwiegend als Beschleunigungsmesser.Die elektrophysiologischen Untersuehungsergebnisse stimmen gut mit den auf Grund der Schwingungsmessungen gefundenen Eigenschaften überein. In der vom Antennennerven abgenommenen elektrophysiologischen Signalspannung werden reizsynchrone Pulssalven beobachtet, denen sich bei steigender Erregungsfrequenz ein synchrones Summenpotential überlagert. Vergleiche mit den mechanischen Untersuchungsergebnissen zeigen, daß das Summenpotential seinen Ursprung im Johnstonschen Organ hat. Die Amplitude dieses Signals steigt proportional mit der Relativbewegung zwischen Flagellum und Pedicellus an; sie ist in einem weiten Bereich unabhängig von der Frequenz.Der Käfer ist in der Lage, äußerst feine Erschütterungen der Wasserfläche wahrzunehmen. Wasserwellen, deren Amplitude nur wenige m beträgt, bringen das Johnstonsche Organ zum Ansprechen. Die Empfindlichkeit nimmt mit steigender Frequenz zu. Hat der Käfer eine Eigengeschwindigkeit, die der Ausbreitungsrichtung eines Wellenzuges entgegengerichtet ist, so erkennt er diese Wellen auf Grund des Doppier-Effektes besser. Mit einer ähnlich guten Empfindlichkeit nimmt der Käfer in der Nähe von Hindernissen den Meniskus wahr. Die ansteigende Wasserfläche ruft infolge der Eigengeschwindigkeit des Käfers eine zeitlich sich ändernde Antennenauslenkung hervor. Bei normalen Schwimmgeschwindigkeiten ist sie bereits in der Entfernung von 0,5–1,5 cm vom Rand so groß, daß der Käfer reagiert.

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On the orientation of Gyrinus substriatus StephWhirligig beetle

Summary The orientation of whirligig beetles Gyrinus substriatus on the surface of water by means of the antennae has been investigated. Whirligig beetles are very sensitive to waves on the surface and are able to find out the direction from where the waves come. They are also able to perceive objects which dip into the water surface and form a meniscus.The antennae have been investigated mechanically and electrophysiologically. Mechanic percussions produce movements between the pedicellus and the flagellum which does not touch the surface of water (Figs. 2, 14). These movements excite the Johnston-Organ. Pedicellus and Flagellum form a vibration system; the resonance-frequency is about 250 Hz and the relative attenuation constant is about 0,7. In the interesting frequency range below 150 Hz the system is mainly measuring accelerations.The results of electrophysiological investigations show a good conformity with those found by mechanical measurements. In the electrophysiological signal, derived from the antenna nerve, groups of spikes are to be observed which are in synchronism with the exciting signal. By increasing the exciting frequency a synchronous sum potential appears which is superimposed upon the original signal (Figs. 19...21).Comparisons with mechanical investigations show that the sum potential has its origin in the Johnston-Organ. The amplitude of this signal increases proportionally to the relative motion between flagellum and pedicellus, independent of frequency in a wide range (Fig. 23).The beetle is able to perceive very small percussions of the surface of water. Waves on the surface with an amplitude of several m produce a response in the Johnston-Organ. The sensivity increases with increasing frequency (Fig. 31). If the beetle is moving against a train of waves, it will perceive them better by reason of the Doppler-Effect.The sensivity is similar when the beetle approaches the meniscus near objects. The inclined water surface produces an excursion of the antenna as a function of time depending on the velocity of the beetle. At normal velocities and in an distance of 0.5–1.5 cm this effect will be large enough to produce a response (Fig. 32).

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Der Verfasser dankt Herrn Prof. Dr.-Ing. habil. H. Tischner und Herrn Dr.-Ing. A. Schief für die Anregung zu diesen Untersuchungen und dem Herrn Ministerpräsidenten des Landes Nordrhein-Westfalen — Landesamt für Forschung — für die Bereitstellung der Mittel.     

A phase I trial of recombinant tumor necrosis factor (rTNF) administered by continuous intravenous infusion in patients with disseminated malignancy

rTNF was administered to 28 patients with advanced metastatic cancers by continuous intra venous infusion for 5 consecutive days every 2 weeks. The dose levels were 30, 40, 70, 110, 180 and 290 µg/M²/day. Groups of 3 patients were started at each successive dose level and then on subsequent courses treated with the next dose level through 4 escalations as tolerated. Tumor types were: colon cancer 14; adenocarcinoma of unknown primary, 2; renal cancer, 2; leiomyosarcoma, 2; lung cancer, 1; prostate cancer, 1; thymona, 1; bladder cancer; 1; parotid, 1; Kaposi's sarcoma 2; ovarian 1. Toxicities included fever and chills (usually within the first 8 hours of infusion), fatigue, headache, decreased performance status, hypotension and CNS. All patients experienced leukopenia and thrombocytopenia within 24 hours or less after start of infusion with return of baseline by 72 hours after rTNF was stopped. The fall in these counts averaged 50% and was not dose related. No major changes in liver or renal function, coagulation or blood lipids were seen. Major dose limiting toxicities were fatigue, confusion, thrombocytopenia, seizures, hypotension and decreased performance status. NK cell activity measured against K562 target cells was augmented from about 30% target cell lysis to about 70% target cell lysis over the first 7 days of treatment. Two patients, both with metastatic colon cancer showed transient, objective tumor regression which did not qualify as a partial response. One patient with ovarian cancer had a stable partial response but progressed after 13 courses of treatment. Continuous infusion of TNF can be safely administered to patients with a maximum tolerated dose of only between 30 and 40 µg/M²/day. In addition, the MTD with continuous infusion seems to be highly variable and unpredictable from patient to patient. These data suggest that continuous infusion will not be an optimal way to administer TNF.     

Depth of the facial nerve in face lift dissections

Facial nerve depth was measured in 12 cadaver face halves after bilateral face lift dissections. The main nerve trunk emerged anterior to the midearlobe and was 20.1 +/- 3.1 mm deep. Nerve exit from the parotid edge also was deep, averaging 9.1 +/- 2.8 mm for temporal, 9.2 +/- 2.2 mm for zygomatic, 9.6 +/- 2.0 mm for buccal, and 10.6 +/- 2.7 mm for mandibular branches. Distal to the parotid gland, danger areas where nerve branches became superficial were distal temporal, lower buccal, and upper mandibular branches over the masseter muscle and marginal mandibular as it crossed the facial artery. Some protection in these danger areas was provided by fascia, especially superficial temporal and masseteric, while platysma provided some protection for the mandibular branch. Fascial and muscle protection was less in thin cadavers. Face lift dissection can be rapid in areas where facial nerve branches are deep or absent, such as postauricular, inferior to the zygomatic prominence, and near the earlobe.     

Molecular analysis of theArabidopsis pattern formation geneGNOM: gene structure and intragenic complementation

TheGNOM gene is required for pattern formation along the main body axis of the embryo in the flowering plantArabidopsis thaliana. Mutations in theGNOM gene alter the asymmetric division of the zygote and interfere with the formation of distinct apical-basal regions in the developing embryo. We have isolated theGNOM gene by positional cloning, characterised its structure and determined the molecular lesions in mutant alleles. Although the predicted 163 kDa GNOM protein has a conserved domain in common with the yeast secretory protein Sec7p, it is most closely related in size and overall similarity to the product of the yeastYEC2 gene, which is not essential for cell viability. Four fully complementinggnom alleles carry missense mutations in conserved regions, seven partially complementing alleles have premature stop codon mutations and two non-complementing alleles have splice-site lesions. Our results suggest that the GNOM protein acts as a complex of identical subunits and that partial complementation may involve low levels of full-length protein generated by inefficient translational read-through.Communicated by H. Saedler     

INVITED SPECIAL PAPER: History of the botanical teaching laboratory in the United States

The establishment of teaching laboratories for botany in the United States was strongly influenced in the early part of the 19th century by the founding of a laboratory of natural history at the Rensselaer School by Amos Eaton who inspired numerous educators, particularly women. By midcentury and later, botany programs were established at land-grant colleges and the so-called “new Botany” movement spread from them. In the latter part of the century additional changes were brought about by the influence of German laboratory activity and botanists’ reactions to the introduction of the Huxley-Martin biology programs to America. During these times, Americans were improving their own manufactured microscopes, laboratory supplies, and equipment capabilities. By the beginning of the 20th century, laboratory teaching of botanical subjects was widely accepted as normal in universities and colleges, as well as in some high schools.