The formation of the front part of the neural tube

Zusammenfassung Die Ontogenese des Zentralnervensystems durchläuft drei frühe Entwicklungsphasen: Proneuromerie, Neuromerie und Postneuromerie. Danach folgen: distale Zellmigrationen in die Neuralrohrwand. Sämtliche Phasen sind mit der Mitosenaktivität korreliert.     

Photoperiodic regulation of mating behaviour in the linden bug,Pyrrhocoris apterus,is mediated by a brain inhibitory factor

Active inhibition of mating behaviour in a male insect is reported here for the first time. InPyrrhocoris apterus L. (Heteroptera), the most important inhibitory pathway runs from the pars intercerebralis (PI) of the brain and does not pass through the corpora allata. The inhibitory activity of the PI is promoted by short day conditions and suppressed by long days. As the effect of photoperiod is delayed, transfer procedures enabled us to record daily rhythms in mating behaviour during short days. While the extirpation of the PI results in a discrete phase shift of the long day rhythm, there is a much less significant phase shift after this operation during short days. Thus the PI has been shown to mediate the effect of photoperiod on both the inhibition and the rhythm of mating behaviour.     

Inorganic polyphosphate induces accelerated tube formation of HUVEC endothelial cells

In this study, the effect of inorganic polyphosphate (polyP) on the initial phase of angiogenesis and vascularization was investigated, applying the HUVEC cell tube formation assay. PolyP is a physiological and high energy phosphate polymer which has been proposed to act as a metabolic fuel in the extracellular space with only a comparably low ATP content. The experiments revealed that polyP accelerates tube formation of human umbilical vein endothelial cells (HUVEC), seeded onto a solidified basement membrane extract matrix which contains polyP-metabolizing alkaline phosphatase (ALP) activity. This effect is abolished by co-addition of apyrase, which degrades ATP to AMP and inorganic phosphate. The assumption that ATP, derived from polyP, activates HUVEC cells leading to tube formation was corroborated by experiments showing that addition of polyP to the cells causes a strong rise of ATP level in the culture medium. Finally, we show that at a later stage of cultivation of HUVEC cells, after 3 d, polyP causes a strong enhancement of the expression of the genes encoding for the two major matrix metalloproteinases (MMPs) released by endothelial cells during tube formation, MMP-9 and MMP-2. This stimulatory effect is again abrogated by addition of apyrase together with polyP. From these results, we propose that polyP is involved either directly or indirectly in energy supply, via ALP-mediated transfer of energy-rich phosphate under ATP formation. This ATP is utilized for the activation and oriented migration of endothelial cells and for the matrix organization during the initial phases of tube formation.     

Isolation and physical-chemical characterization of a humoral,sleep inducing substance in rabbits (factor ‘delta’)

Zusammenfassung Das Hämodialysat schlafender Kaninchen (unter Einfluss thalamischer Reizung) wurde unter Kontrolle der «Delta-Schlaf»-induzierenden Aktivität fraktioniert. Nach Entsalzung über Sephadex G-10 wurde die hypnogene Fraktion durch anschliessende präparative Dünnschichtchromatographie in 6 verschiedene ninhydrin-positive Fraktionen getrennt (MG>Cl^–). Eine davon enthielt die hypnogene Aktivität. Diese Fraktion 2 wurde über Sephadex G-15 in 3 ninhydrin-positive Gipfel aufgetrennt. Nur die Fraktion mit dem geringstenV _e enthielt die hypnogene Aktivität. Durch Vergleich mit dem Elutionsvolumen von Markersubstanzen konnte für die aktive Substanz ein Molekulargewicht zwischen 355 und 1500 geschätzt werden. Präparative Hochspannungs-Papierelektrophorese trennte das aktive Material in vier Unterfraktionen. Nur eine elektrophoretisch und chromatographisch einheitliche Fraktion (2) enthielt die hypnogene Aktivität. Aus dieser Fraktion wurden nach saurer Hydrolyse mindestens 7 verschiedene Aminosäurereste freigesetzt. Dieses Resultat wurde durch Dansylierung vor und nach saurer Hydrolyse verifiziert; gleichzeitig wurden Artefakte durch kontaminierende Aminosäuren aus dem Papier ausgeschlossen. Die Ergebnisse lassen auf die Peptidnatur einer humoralen «Delta-Schlaf»-induzierenden Substanz schliessen (sleep factor delta).     

Assortative mating between chromosome forms of the mole rat,Spalax ehrenbergi

Females of two parapatric chromosomal forms (2n=52 and 2n=58) of the fossorial mole rat,Spalax ehrenbergi, in Israel, were tested for mate selection between two alternative, a homo- and a heterochromosomal, males. Estrous females significantly preferred the male of their own chromosomal form, on the basis of several behavioural criteria. The evolutionary significance of the positive assortative mating found, lies presumably in reinforcing reproductive isolation between the chromosome forms, thereby contributing to finalize speciation.     

Comparison of the biological effects of anemia inducing and polycythemia inducing Friend virus complex

Summary The comparison of the biological effects of FV^P and FV^A showed that leukemogenesis appears to be delayed in FV^A infected mice as compared to FV^P infected animals after injection of comparable quantities of virus as measured in spleen focus forming units. In addition, no CFU-EI, characteristic for FV^P induced leukemia, were found in leukemic spleen or bone marrow of FV^A infected mice. Since it was possible to distinguish both viruses by their different host ranges, which are helper virus determined, it is suggested that the observed differences, especially the lack of CFU-EI in FV^A infected mice, might be due to differences in the helper virus component of the FV complex.Supported by the Deutsche Forschungsgemeinschaft (SFB 112 Zellsystemphysiologie).     

Synthesis of oxytocin: Suppression of dimer formation

Zusammenfassung Die Bildung von Oxytocin-Dimer (+), einem Nebenprodukt der Oxytocin-Synthese, wird verringert durch Ausschluss atmosphärischen Sauerstoffes während der Zyklisation von Oxytocein zu Oxytocin. Das Gleichgewichtsverhältnis von Monomer zu Dimer wird durchschnittlich von 41 auf 111 verbessert.     

Comparison of the biological effects of anemia inducing and polycythemia inducing Friend virus complex.

The comparison of the biological effects of FVP and FVA showed that leukemogenesis appears to be delayed in FVA infected mice as compared to FVP infected animals after injection of comparable quantities of virus as measured in spleen focus forming units. In addition, no CFU-EI, characteristic for FVP induced leukemia, were found in leukemic spleen or bone marrow of FVA infected mice. Since it was possible to distinguish both viruses by their different host ranges, which are helper virus determined, it is suggested that the observed differences, especially the lack of CFU-EI in FVA infected mice, might be due to differences in the helper virus component of the FV complex.     

Assortative mating between chromosome forms of the mole rat, Spalax ehrenbergi.

Females of two parapatric chromosomal forms (2n = 52 and 2n =58) of the fossorial mole rat, Spalax ehrenbergi, in Israel, were tested for mate selection between two alternative, a homo- and a heterochromosomal, males. Estrous females significantly preferred the male of their own chromosomal form, on the basis of several behavioural criteria. The evolutionary significance of the positive assortative mating found, lies presumably in reinforcing reproductive isolation between the chromosome forms, thereby contributing to finalize speciation.     

A frosty disagreement: John Tyndall,James David Forbes,and the early formation of the X-Club

How do glaciers move? This seemingly straightforward question provided the backdrop for a heated debate between the physicists John Tyndall (1820–1893) and James David Forbes (1809–1868) in the late 1850s and early 1860s. Forbes described the motion of glaciers as that of a viscous fluid. After visiting the Alps, Tyndall proposed an alternative theory that combined fracture and regelation. The glacial controversy ensued. Yet the debate was never simply about whether glaciers moved like honey, or if they moved by continuously breaking and re-attaching. This paper shows that the glacial controversy formed an important prelude to the strategies used by the X-Club in reforming science and establishing cultural authority. There was a central difference in the way Forbes and Tyndall presented their scientific arguments. Tyndall and his allies used the changes in the periodical press as part of their strategy for establishing and maintaining cultural and scientific authority. By contrast, Forbes and his supporters, including the North British physicists, were not as quick to make use of this new medium. This paper, therefore, examines in detail the significance of these two publishing strategies in shaping the nature and results of the glacial controversy.     

Dual role of mating in egg production and survival in the cricket,Plebeiogryllus guttiventris walker

Zusammenfassung Bei der Kopulation der GrillePlebeiogryllus guttiventris werden mindestens 2 unabhängige Stimuli wirksam, welche Oviposition und Eiproduktion beeinflussen. Weder künstliche Spermatophorenübertragung noch Kopulation mit kastrierten Männchen stimuliert die Oviposition; letztere bewirkt aber erhöhte Eiproduktion. Künstliche Übertragung von Spermatophoren in hungernde, virgine Weibchen reduziert die Eiproduktion und bewirkt eine Lebensverlängerung.