Effect of visual cues from female on the postejaculatory operant behavior of male rat

Bar-press response reinforced by the contact with estrous female were investigated in male rats in two experimental situations, when the visual communication with female was prevented or when it was permitted. After the instrumental responses directly preceded by ejaculations, depending on the increasing duration of response latency, three categories of male behavior were observed: avoiding of the contact with female, precopulatory behavior, or copulatory behavior. The enabling the visual communication with a female caused the significant increase of occurrence of copulatory behavior and significant decrease of contact-avoiding behavior, whereas the precopulatory behavior showed unsignificant increase. It is suggested that when prevented to see the female male rats can perform the instrumental response even when the sexual arousal is to low for precopulatory behavior. Such unrewarded responses lead to the appearance of frustration. On the contrary, when the female is visible the instrumental response is delayed up to the moment when the visual cues coming from female can evoke at least precopulatory behavior.     

Electrorotation of lymphocytes—The influence of membrane events and nucleus

Electrorotation—the spin of cells in rotating high frequency electric fields—has been used to investigate properties of human peripheral blood lymphocytes. The rotation spectra of lymphocytes deviate from those of single shell spheres. The deviations are caused by the electrical properties of the nucleus in the cell interior.Electrorotation allows the distinction between successfully stimulated lymphocytes and unstimulated cells after application of concanavalin A. Notwithstanding the fact that only a proportion of the cells will be mitogenically stimulated we detected an enhanced cell membrane conductivity for the whole cell population immediately after the addition of mitogen.     

Rate theory models for ion transport through rigid pores. I. Time-dependent analysis in the case of vanishing interactions

In this first of a series of papers concerning the theoretical analysis of rate theory models for ion transport through rigid pores, the case of vanishing interactions is investigated. "Rigidity" means that ions crossing membranes through pores see a fixed structure of the pores, not changing in time. A single pore is considered to be a sequence of (n + 1) activation barriers separated by n energy minima. The explicit analytical treatment is restricted to pores with regular internal barrier structure, including the nonequilibrium situation of an applied electric field. In this case the connection with continuum diffusion models is demonstrated by performing in the limit n leads to infinity (n = number of binding sites within the pores) the transition to continuum. Thus, from diffusion equations describing a discrete number of jumps, the corresponding diffusion-like partial differential equations and boundary conditions are generated. For regular pores, from the time dependent solutions of the discrete equations, the corresponding solutions of the continuum equations are explicitly generated. The time-dependent relaxation behaviour of the discrete model is in good agreement with the continuum model if one assumes more than two binding sites in the pores.     

Uptake of l-Ascorbate by Intact Spinach Chloroplasts

Uptake of l-[1-¹⁴C]ascorbate by intact ascorbate-free spinach (Spinacia oleracea L. cv Vital^r) chloroplasts has been investigated using the technique of silicone oil filtering. Rates greater than 100 micromoles per milligram chlorophyll per hour (external concentration, 10 millimolar) of ascorbate transport were observed. Ascorbate uptake into the sorbitol-impermeable space (stroma) followed the Michaelis-Menten-type characteristic for substrate saturation. A K_m of 18 to 40 millimolar was determined. Transport of ascorbate across the chloroplast envelope resulted in an equilibrium of the ascorbate concentrations between stroma and medium. A pH optimum of 7.0 to 7.5 and the lack of alkalization of the medium upon ascorbate uptake suggest that only the monovalent ascorbate anion is able to cross the chloroplast envelope. The activation energy of ascorbate uptake was determined to be 65.8 kilojoules (16 kilocalories) per mole (8 to 20°C). Interference of ascorbate transport with substrates of the phosphate or dicarboxylate translocator could not be detected, but didehydroascorbate was a competitive inhibitor. Preloading of chloroplasts with didehydroascorbate resulted in an increase of V_max but did not change the K_m for ascorbate. Millimolar concentrations of the sulfhydryl reagent p-chloromercuriphenyl sulfonate inhibited ascorbate uptake. The data are interpreted in terms of ascorbate uptake into chloroplasts by the mechanism of facilitated diffusion mediated by a specific translocator.     

Placental alkaline phosphatase types in Germany

Summary Two children with autosomal deletion (46,XY,del(12)(p11) and 46,XY/46,XY, del(5)(p13)) and normal phenotype were found among 5049 consecutive newborn children. The mother of the proband with deletion short arm 5 had the karyotype 46,XX,9qh+, but the parents had otherwise normal chromosome constitution.

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Zusammenfassung Zwei Kinder mit autosomaler Deletion (46,XY,del(12)(p11) und 46,XY/46,XY,del(5)(p13)) bei normalem Phänotyp wurden unter 5049 auslesefrei gewonnenen Neugeborenen entdeckt. Die Mutter des Probanden mit der Deletion am kurzen Arm von Nr. 5 hatte den Karyotyp 46,XX,9qh+; sonst hatten die Eltern normale Chromosomen.

     

Tagesperiodik,Revierverhalten und Beutefang der Geißelspinne Admetus pumilio C. L. Koch im Freiland*

Auf einer Fläche von ca. 40 × 60 m eines Regenwaldes bei Manaus/Amazonas wurden über 30 Admetus pumilio untersucht, sowie Temperatur, Feuchte und Helligkeit im Biotop registriert. Man findet immer nur ein Tier in einer Höhle am Fuß großer Bäume; nahezu jedes derartige Versteck ist besetzt. Der Aktivitätsverlauf zeigt im Freiland 3 Aktivitätsschübe: der abendliche dient der Nahrungsaufnahme, der nachmitternächtliche dem Verlassen des engeren Reviers zu Partnersuche oder zum Höhlenwechsel, der morgendliche zur Rückkehr ins Versteck. Der Aktivitätsbeginn gegen 16 Uhr ist endogen, das Aktivitätsende gegen 6.30 Uhr weitgehend exogen bestimmt. Der Rückzug in die Höhle am Morgen erfolgt bei 10fach niedrigerer Helligkeit als der Auszug aus dieser am Abend. Adulte Geißelspinnen behalten über mehrere Wochen die gleiche Höhle bei; beobachtet wurde bis zu 65 Tagen. Innerhalb eines untersuchten Umkreises von 7—10 m können sie sich hervorragend orientieren — vermutlich olfaktorisch. Die Beutefanghandlung wird beschrieben und die Orientierung hierbei analysiert. Zwei mechanorezeptorische Systeme werden nach- oder nebeneinander wirksam: Trichobothrien auf den Schreitbeinen leisten die Fernorientierung und dirigieren die Annäherung an die Beute bis in den Wirkungsbereich der Tastbeine, die die Orientierung im Nahbereich übernehmen, vor allem beim Packen der Beute. Die kutikularen Haarsensillen auf den Beinen werden kurz beschrieben.     

A COMPARATIVE STUDY OF THE PRIMARY VASCULAR SYSTEM OF CONIFERS. I. GENERA WITH HELICAL PHYLLOTAXIS

The primary vascular system of 23 species belonging to 18 genera of conifers with helical phyllotaxis has been investigated with the intent of determining the architecture of the system. Special attention has been given to nodal and subnodal relations of the vascular bundles. The vascular system seems to be composed solely of relatively discrete sympodia, that is, axial vascular bundles from which leaf traces branch unilaterally. Although the discreteness of the sympodia is not immediately apparent because of their undulation and lateral contacts with neighboring ones, close examination, including a statistical analysis of the tangential contacts, seems to reveal that each sympodium maintains its identity throughout. Although two traces may be apparent at nodal levels, the trace supply to a leaf originates, in all species, as a single bundle. An analysis is made of the relationship between the vasculature and the phyllotaxis. It is observed that the direction of trace divergence can be accurately predicted when the direction of the ontogenetic spiral, the angle of divergence of leaf traces, and the number of sympodia are known.