Optische Eigenschaften der Ommatidien im Komplexauge von Musca

Summary Optical characteristics of the dioptric system in the ommatidia of Musca have been analysed by use of antidromic illumination of the eye. The results indicate that the distal endings of the rhabdomers terminate near the focal plane of the dioptrics and that the quality of the lens is high enough to resolve some details of their shape. — Using optical methods it has been possible to confirm directly that the optical axes of 7 individual rhabdomers from 7 different ommatidia all converge to a common point in the distant surroundings. This is a characteristic for compound eyes of the neural superposition type. — The results are discussed on the basis of the hypothesis that the Musca eye is composed of two functionally different subsystems: One system (D) with high absolute sensitivity and low spatial resolution consisting of the sense cells no. 1 to 6, and a second system (H) with high spatial resolution and low absolute sensitivity composed of cells no. 7 and 8.

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Wir danken Herrn Dr. K. G. Götz, Herrn Prof. W. Reichardt und Herrn Dr. D. Varjú für wertvolle Diskussionen, Fräulein T. Wiegand für Mithilfe bei den Experimenten, sowie Herrn E. Freiberg für das Fertigstellen der Abbildungen.     

Die Verarbeitung stationärer optischer Nachrichten im Komplexauge von Limulus

Summary The functional properties of the processing of visual information by the complex eye of Limulus was studied. The spatial distribution of activity that results in the optic nerve when the Limulus eye is exposed to a stationary optical pattern depends upon the transfer characteristics of two subsystems: the dioptric apparatus and the nervous interactions comprising the lateral inhibition system. — The transfer characteristic of the dioptric apparatus is determined by the sensitivity distribution function of single ommatidia. This distribution was measured and found to be approximately of Gauss-function type. The sensitivity falls off to 1/e at a distance of one ommatidium; thus the visual fields of adjacent ommatidia strongly overlap. As a consequence of the overlap, amplitudes of the spatial Fourier components, of which the brightness distribution of the optical surround is made up, are more and more reduced with increasing frequency in the intensity distribution on the receptor mosaic. The amplitude of the spatial frequency 1/=0,25 ( in units of interommatidial distance) is reduced to half of the maximum value, which is attained at zero frequency. It is shown that the amplitude frequency characteristic of the sensitivity distribution function has no zeros, which means that no loss of optical information results from overlap of visual fields. Thus the resolving power of the dioptric apparatus is limited only by the number of receptors per unit area. — The transfer characteristic of the lateral inhibition system in the Limulus eye depends on the distribution of the inhibitory coefficients around the individual receptors. This distribution function was determined from excitatory responses in the optic nerve elicited by a spatial light intensity step function on the receptor mosaic. It is found that this distribution is also Gaussian in form, but decays to 1/e at a distance of eight to nine ommatidia along the major axis of the eye. The average value of the inhibitory coefficients between adjacent ommatidia was found to be 0,025. The amplitude frequency response of the inhibitory system is constant for high spatial frequencies down to 1/=0,1 while amplitudes of lower frequency sinusoids are reduced down to nearly half of the maximum value at frequency zero. The amplitude frequency characteristic of the inhibitory system ensures a one to one correspondence between the intensity distribution on the receptor mosaic and the excitation distribution in the optic nerve. The overall transfer characteristic of the eye is derived from the transfer characteristics of the dioptric apparatus and the inhibitory system. This characteristic is of bandpass type with a maximum amplitude response at a frequency of 1/=0,07. The overall transfer characteristic was independently confirmed in a separate experiment. The nature of the overall transfer characteristic shows that the inhibitory system does not exactly correct for the overlap of the visual fields of single ommatidia, which in principal the system could do if the distributions of inhibitory coefficients and ommatidia sensitivity were equal. The overall transfer characteristic of the Limulus eye garantees a one to one correspondence between patterns in the optical surround and excitation distributions in the optic nerve. — The average values of the inhibitory coefficients derived from these experiments are at least a factor ten smaller than those determined directly by other investigators. Possible explanations of this discrepency are discussed. — In a separate chapter the overall transfer characteristic for eyes submerged in water is described. It was found that this characteristic does not differ from that determined in air for the eye region which was investigated in the experiments. This result is explained by two properties of the eye which are dependent on the refractive index of the surround medium and whose influences cancel each other: the visual fields of ommatidia are reduced under water, while the divergence angles between the optical axes of adjacent ommatidia also diminish.

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This research was supported in part by the United States Air Force under Grant No. AF-EOAR-62-41 and monitored by the European Office, Office of Aerospace Research.     

Optomotorische Untersuchung des visuellen systems einiger Augenmutanten der Fruchtfliege Drosophila

Summary The optical properties of the compound eye of Drosophila have been analysed using the optomotor reactions of flies with normal and mutant eye pigmentation. The stimulus was provided by cylindrical patterns with different periodic intensity distributions rotating at different speeds. The response consists of a torque about the vertical axis and was recorded under conditions of fixed flight. (Maximum reaction is about 0.04 dyn · cm). The transfer characteristics of the optical system are determined by the inter-ommatidial angle , influencing the resolving power and by the width of the visual field of single ommatidia , influencing the response at high spatial frequencies. The values = 4.6° and = 3.5° are obtained from stimulus-response experiments with Drosophila. They are independent of the presence of screening pigments. Differences in the response of flies with strong (+, se), weak (w ^a), and missing (w) pigmentation can be explained by the increased amount of scattered light in the pigment-deficient eyes. The overall intensities in the equally illuminated receptors are expected to be in the ratio 11825, respectively. The perception of motion depends only on the temporal, not on the spatial phase relations between periodic intensity variations in neighbouring ommatidia. Therefore the inhomogeneous distribution of the inter-ommatidial angle changes the resolving power in different parts of the eye without changing the response to motion. Different simultaneous stimuli of equal strength in different parts of the eye are averaged in the perceptive system of Drosophila according to the number of ommatidia in these parts.     

Die Sehfelder der zentralen Ommatidien in den Appositionsaugen von Apis mellifica und Cataglyphis bicolor (Apidae,Formicidae; Hymenoptera)

Experimental equipment has been developed to make possible continuous recordings of intensity distribution curves as a function of angle of incidence of light in single ommatidia of arthropod compound eyes. — As preliminary experiment, the visual fields of ommatidia in Limulus, Apis and Cataglyphis have been ascertained without a light measuring instrument. A point source was moved through the visual field and the angular position of the light source on both sides of the visual field at which the rhabdome in the cut-off eye viewed from proximal turned dark was determined. In the dorsal part of the Limulus eye, the cranio-caudal width of the visual field is 42.6±0.3°. The width of the visual field of central ommatidia in Apis is 6.68±0.14° in the dorsoventral plane and 7.42±0.24° in the cranio-caudal direction, in Cataglyphis 15.5±0.5° and 12.5±0.4° respectively.— Similar Gaussian curves for light and dark adapted ommatidia resulted from the continuous recordings of intensity distribution curves in Apis. The rotatory symmetric curve of the worker bee has a half-width of =2.57°. The standardized curve of amplitude one may be approximated by the function y=exp (-0.41 [degree^–2] ²). In Cataglyphis, the half-width of the intensity distribution curve is =8.8° in the dorso-ventral plane and =6.8° in the cranio-caudal plane. Near the axis, the functions y=exp(-0.04 [degree^–2]²) and y=exp(-0.06 [degree^–2] ²) approximate the standardized curves. — Knowledge of intensity distributions in connection with interommatidial angles allows estimation of contrast transfer and resolving power of the array of the dioptric systems. Correlations with behavioural findings are attempted.

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Mit Unterstützung durch den Schweizerischen National-fonds zur Förderung der wissenschaftlichen Forschung, Kredit Nr. 3.315.70, die Eidgenössische Konstruktionswerkstätte (Thun) sowie die Firmen Philips AG (Zürich) und Wild AG (Heerbrugg).     

Bau und optische Leistungen des Komplexauges der StielaugenfliegeCyrtodiopsis dalmanni Wiedemann

Zusammenfassung Die großen Sehfelder der Komplexaugen der malayischen StielaugenfliegeCyrtodiopsis dalmanni überschneiden sich 3–4 mm vor den Augen. Eine Entfernungswahrnehmung von Objekten, die sich in den Sehfeldern beider Facettenaugen befinden, ist deshalb sehr wahrscheinlich.Interferometrische Messungen amCyrtodiopsis-Auge führten zu gleichen Brechungsquotienten für die Ommatidienstrukturen wie beiCalliphora erythrocephala. Die geometrischoptischen Berechnungen ergaben für den dioptrischen Apparat des Ommatidiums imCyrtodiopsis-Auge eine objektseitige Brennweite von 29 m. Hieraus und aus den Durchmessern der Rhabdomeren-Kappen — sie liegen in der Brennebene — resultieren die Öffnungswinkel von2,5° für die Rhabdomere 1–6 und von1,6° für das 7. Rhabdomer. Diese Öffnungswinkel sind kleiner als die der Ommen, die bei8,8° liegen. Im einzelnen Ommatidium kann eine höhere Auflösung erzielt werden, da die Beugungsscheibe jeweils nur eine Kappe bedeckt.

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Morphology and physiology of the compound eye of the stalked-eye flyCyrtodiopsis dalmanni Wiedemann

Summary The large visual fields of the compound eyes of the Malayan flyCyrtodiopsis dalmanni overlap 3–4 mm in front of the eyes. Depth perception of objects placed within the visual fields of both eyes is therefore very probable. Interferometrical studies on theCyrtodiopsis eye indicated that refractive indices of the ommatidial structures are the same as in the blowfly. The focal length of the dioptric apparatus of the stalked-eye fly ommatidium was found to be 29 m on the object side. The angles of aperture calculated from this focal length and from the diameters of the corresponding rhabdomeric prolongations—located in the focal plane-are 2.5° for the rhabdomeres 1–6, and 1.6° for the rhabdomere 7. These opening angles are smaller than those of the ommatidia, which are about 8.8°. Calculations based on the diffraction theory lead to the conclusion that higher resolution is obtained in the single ommatidium because the airy disc covers only one rhabdomeric prolongation.

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Mit Unterstützung der Deutschen Forschungsgemeinschaft.     

Some optical features of the eyes of stomatopods

The optics of a variety of stomatopod eyes has been investigated using goniometric eye-mapping techniques and anatomical measurements. The species examined come from 3 of the 4 existing superfamilies: the Gonodactyloidea, Lysiosquilloidea and Squilloidea. This paper examines acuity, optical axes and general features of eye shape. Stomatopod eyes are divided into 3 clearly distinct zones; the mid-band and two hemispheres. Each hemisphere consists of an edge region, a visual streak and a near mid-band region. The optical axes of many ommatidia from both hemispheres are skewed inwards towards the centrally placed mid-band and are rarely normal to the corneal surface. The large skew angle enables each hemisphere to examine an area which extensively overlaps that of the other hemisphere. As a result monocular distance judgement is possible. Most of the ommatidia in each hemisphere are part of a horizontally aligned but vertically acute visual streak area. There is one visual streak per hemisphere and both look into the same 5–10° strip. This narrow strip is also the area in space the mid-band ommatidia examine. An acute zone is present in the eyes of lysiosquilloid and gonodactyloid stomatopods and includes ommatidia, from both the hemispheres and the mid-band. Here inter-ommatidial angles, especially those in the horizontal direction, are reduced. Acute zone facets are enlarged to increase sensitivity rather than aid spatial resolution.Abbreviations and definitions AZ Acute Zone - MB Mid-band - D Corneal facet diameter, as MB facets are asymmetrical, values for width and height of each facet are given - DH dorsal hemisphere - f Focal length of each ommatidium, estimated from the centre of the corneal lens to the tip of the rhabdom - NeMB Near mid-band ommatidia - R Resolving power=1/2_average - R_h Horizontal resolving power=1/2_h - R_v Vertical resolving power=1/2_v - VH ventral hemisphere - Geometrical acceptance angle (a/f×57.3) of each ommatidium - _h Horizontal inter-ommatidial angle, between facets along a row - _v Vertical inter-ommatidial angle, between rows; Superfamily Gonodactyloidea - g.c. Gonodactylus chiragra - O.s. Odontodactylus scyllarus - H.e. Hemisquilla ensigera; Superfamily Lysiosquilloidea - L.t. Lysiosquilla tredecimdentata - C.s. Coronis scolopendra; Superfamily Squilloidea - O.o. Oratosquilla solicitans     

The eyes of mesopelagic crustaceans

Summary In Streetsia challengeri left and right eyes have fused and become a single cylindrical photoreceptor, which occupies the basal half of a forward directed head projection. This unusual compound eye consists of approximately 2500 ommatidia, which are arranged in such a way that the animal has almost circumferential vision, but cannot look ahead or behind. It is thought that the eye operates on light-guide principles, and that the crystalline cones are the major dioptric component. Ommatidia in anterior-posterior rows show a greater overlap of visual fields than dorso-ventrally arranged ommatidia. Cone layer and retinula are separated by a 4 m thick screen-membrane, which contains tiny pigment granules of 0.15 m diameter. Cells of unknown function and origin, containing unusual multitubular organelles, are regularly found near the proximal ends of the crystalline cone threads. The twisted rhabdoms measure 18–20 m in diameter, and consist of microvilli 0.05 m in width, which belong to five retinula cells and which show no trace of disintegration. The position of interommatidial screening pigment, the density of retinula cell vesicles and inclusions, and the narrowness of the perirhabdomal space all suggest that the eyes have been light-adapted at the time of fixation for electron microscopy. The retinula cell nuclei lie on the proximal side of the heavily pigmented basement membrane. A tapetum or basal retinula cells are not developed. It is concluded that the eye optimally combines acuity with sensitivity, and that for distance estimation parallax may be important.Address until January 25th 1978: Scott Base, Ross Dependency, Antarctica (C/-Chief Post Office, Christchurch, New Zealand)     

Adaptation und Photoregeneration im Fliegenauge

Zusammenfassung Adaptationsversuche mit quantengleichen monochromatischen Lichtern zeigen, daß die Empfindlichkeit der Miegenretina 3 min nach monochromatischer Helladaptation annähernd proportional der Sehfarbstoffkonzentration in den Rezeptoren ist. Spektralphotometrisch wurde nachgewiesen, daß während der Helladaptation sich photochemische Gleichgewichte zwischen dem Sehpigment P 490–500 und einem thermostabilen Folgefarbstoff M 550–560 einstellen.

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Adaptation and photoregeneration in the eye of the blow fly

Summary Adaptation with equal quanta monochromatic lights causes in the photoreceptors of the blow flyCalliphora three minutes after cessation in darkness an increase of threshold up to a level which is nearly proportional to the concentration of visual pigment P 490–500. Photometric measurements have shown that monochromatic illumination causes a photoequilibrium between visual pigment P 490–500 and its thermostable Metarhodopsin M 550–560.

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Mit Unterstützung der Deutschen Forschungsgemeinschaft im Rahmen des Schwerpunktsprogramms Rezeptorphysiologie und SFB-114. — Die Meßdaten der Abb. 3 stellte freundlicherweise Dr. J. Schwemer zur Verfügung.     

Visual pattern discrimination as an element of the fly's orientation behaviour

Summary The visually guided orientation behaviour of stationarily flying Musca domestica (females) has been investigated. Under such conditions, the flight activity does not influence the visual stimulus (openloop) and the tendency of a fly to orientate towards some visual object can be recorded as a yaw torque reaction (orientation response).—Orientation responses to flickering stripes reveal two different mechanisms of visual integration, namely a local flicker detecting mechanism and a specific kind of dynamic lateral interactions (Figs. 3, 5). The lateral interactions are mediated by a field of interconnections of receptors which are separated by at least 4 to 6 vertical rows of ommatidia (Figs. 3, 8). While stimulation of not more than 3 vertical rows of ommatidia activates only flicker detection, stimuli of more than 6° width may in addition exert an excitatory or an inhibitory influence as a consequence of the associated nonlinear interactions (Figs. 5, 7). The relevance of these lateral interactions for tracking and chasing behaviour is discussed. It is suggested that the fly's visual pattern discrimination rests essentially on these lateral interactions.     

Changes of cytoplasmic free Ca2+ in the green alga Mougeotia scalaris as monitored with indo-1, and their effect on the velocity of chloroplast movements

The fluorescent calcium-sensitive dye 1-[2-amino-5-(6-carboxyindol-2-yl)-phenoxy]-2-(2-amino-5-methylphenoxy)-ethane-N,N,N,N-tetraacetic acid (indo-1) was loaded by a transplasmalemma pH gradient into filamentous cells and protoplasts of Mougeotia scalaris, such that most of the indo-1 fluorescence originated from the cytoplasm. Incubation of M. scalaris filaments in ethylene glycol-bis(-aminoethyl ether)-N,N,N,N-tetraacetic acid (EGTA)-buffered media (-log [Ca²⁺] (=pCa) 8 versus pCa 3) caused a consistent and significant decrease in the cytoplasmic free [Ca²⁺]. Pulses of the fluorescence excitation light (UV-A 365 nm, 0.7 s) caused an increase in cytoplasmic free [Ca²⁺] in M. scalaris that was nearly independent of the external [Ca²⁺] and of chloroplast dislocation by centrifugation. This calcium flux, highest in UV-A light, compared with blue or red light, probably resulted from a release of Ca²⁺ from intracellular stores. Increased cytoplasmic [Ca²⁺] may affect the velocity of chloroplast rotation since UV-A-light-mediated chloroplast movement was faster than in blue or red light. Consistently, the calcium ionophore A23187 and the calcium-channel agonist Bay-K8644 both increased the velocity of the red-light-mediated chloroplast rotation. Based on these and other observations, a Ca²⁺-induced decrease in cytoplasmic viscosity in Mougeotia is presumed to occur.Abbreviations EGTA ethylene glycol-bis-(-aminoethyl ether)N,N,N,N-tetraacetic acid - indo-1 1-[2-amino-5-(6-carboxyindol-2-yl)-phenoxy]-2-(2-amino-5-methylphenoxy)-ethane-N,N,N,Ntetraacetic acid - pCa log [Ca²⁺] - P_fr far-red-absorbing form of phytochrome - P_r red-absorbing form of phytochrome - x_G geometric mean Dedicated to Professor Wolfgang Haupt on the occasion of his 70th birthdayThis paper is part of the Ph.D. thesis of U. Russ at the Justus-Liebig-Universitat Giessen (FRG). Part of this work has been presented at a meeting on Calcium and intracellular signalling in plants in Plymouth, UK, Dec. 1990We are indebted to Dr. G. Seibold and Dipl. Phys. H. Weintraut for their advice on the technique of microspectrofluorometry and for allowing access to the microspectrophotometric facilities in the Strahlenzentrum der Justus-Liebig-Universität, Giessen, FRG. We thank Mrs. A. Quanz for reliable culture of the algae and evaluation of the videotapes. Bay-K8644 was a generous gift of Bayer AG, Wuppertal, FRG. U. russ was supported by a scholarship according to the Hessisches Graduierten Förderungsgesetz. This work was supported by the Deutsche Forschungsgemeinschaft.     

Le contrôle automatique du flux lumineux dans l'oeil composé des Diptères

In the compound eye of the fly Musca, tiny pigment granules move within the cytoplasm of receptor cells Nos. 1–6 and cluster along the wall of the rhabdomeres under light adaptation, thus attenuating the light flux to which the visual pigment is exposed (Kirschfeld and Franceschini, 1969). Two recently developed optical methods (the neutralization of the cornea and the deep pseudopupil) combined with antidromic and orthodromic illumination of the eye (Fig. 1) make it possible to analyse the properties of the mechanism at the level of the single cell, in live and intact insects (Drosophila and Musca). The mechanism is shown to be an efficient attenuator in the spectral range (blue-green) where cells Nos. 1–6 have been reported to be maximally sensitive (Figs. 4c and d, 5b and 11b). In spite of the fact that the granules do not penetrate into the rhabdomere, the attenuation spectrum they bring about closely matches the absorption spectrum of the substance of which they are composed (ommochrome pigment, dotted curve in Fig. 11b). The dramatic increase in reflectance of the receptors after light adaptation (Figs. 3, 4b, 5a and 11a) can be explained as a mere by-product of the high absorption index of the ommochrome pigment, especially if one takes into account the phenomenon of anomalous dispersion (Chapter 8). The vivid green or yellow colour of the rhabdomeres would thus have a physical origin comparable to a metallic glint. Contrasting with the lens eye in which the pupillary mechanism is a common attenuator for both receptor types (rods and cones), the compound eye of higher Diptera is equiped with two types of pupils adapted respectively to both visual subsystems. A scotopic pupil is present in each of the six cells (Nos. 1–6) whose signals are gathered in a common cartridge of the first optic ganglion. This pupil comes into play at a moderate luminance (0,3 cd/m² in Drosophila; 3 to 10 cd/m² in Musca. Figs 13, 14, 15, 16). A photopic pupil is present in the central cell No. 7 whose signal reaches one column of the second optic ganglion. Attenuating the light flux for both central cells 7 and 8, the photopic pupil has its threshold about two decades higher than the scotopic pupil, just at the point where the latter reaches saturation (Fig. 3b, e-State II of Figs. 6b and 15). The photopic pupil itself saturates at a luminance one to two decades higher still (Fig. 3c, f=State III of Figs. 6c and 15). The two-decades-shift in threshold of these pupil-mechanisms supports the view that receptors 1–6 are a scotopic subsystem, receptors 7 and 8 a photopic subsystem of the dipteran eye. The luminance-threshold of the scotopic pupil (as determined with the apparatus described in Fig. 2) appears to be located at least 3.5 decades (Drosophila) or even 5 decades (Musca) higher than the absolute threshold of movement perception (Fig. 16). After a long period (1 hr) of darkness a light step of high intensity can close the scotopic pupil within about 10 sec (time constant 2 sec as in Fig. 9) and the photopic pupil within no less than 30–60 sec. Some mutants of Drosophila possess only a scotopic pupil (w , Figs. 4 and 5) whereas ommochrome deficient mutants lack both types of pupil (v, cn, see Fig. 7c, d). Comparable reflectance changes, accomplished within about 60 sec of light adaptation, are described for two insects having fused rhabdomes: the bee and the locust (Fig. 17).     

Die Auslösung kerninduzierter Regeneration bei gealterten kernlosen Zellteilen vonAcetabularia und ihre Auswirkungen auf die Synthese von Ribonucleinsäure und Cytoplasmaproteinen

Summary By grafting a rhizoid with its nucleus onto one end of an enucleate posterior part ofAcetabularia 21 days after enucleation (transplantation —those parts do not show any morphogenetic capacity or net synthesis—or by injecting an isolated nucleus into it (implantation), regeneration occurs at the opposite end of the old enucleate part after a few days: a new stalk, whorls and finally a cap are formed. During the whole process there is a typical difference in morphology and colour of the former enucleate part and the newly formed regenerate. No changes occur in the amount of RNA and soluble cytoplasmic proteins of the former enucleate parts during 20–23 days whereas the growing regenerate shows a linear increase of both substances during the same time; thus it behaves like a normal growing nucleated cell ofAcetabularia. Removal of the nucleus by cutting off the rhizoid from the graft has the same effects as enucleation of normal cells: the net synthesis of RNA in the regenerate ceases, protein synthesis and morphogenetic capacity continue to function for a limited time.

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Mit 7 Textabbildungen

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Der Deutschen Forschungsgemeinschaft wird für die gewährten Unterstützungen gedankt.     

Elementary detectors for vertical movement in the visual system of Drosophila

Optomotor thrust responses of the fruitfly Drosophila melanogaster to moving gratings have been analysed in order to determine the arrangement of elementary movement detectors in the hexagonal array of the compound eye. These detectors enable the fly to perceive vertical movement. The results indicate that, under photopic stimulation of a lateral equatorial eye region, the movement specific response originates predominantly from two types of elementary movement detectors which connect neighbouring visual elements in the compound eye. One of the detectors is oriented vertically, the other detector deviates 60° towards the anterior-superior direction (Fig. 5b). The maximum of the thrust differences to antagonistic movement is obtained if the pattern is moving vertically or along a superior/anterior — inferior/posterior direction 30° displaced from the vertical (Fig. 3d,e, Fig. 6). Only one of the detectors coincides with one of the two detectors responsible for horizontal movement detection. This indicates that a third movement specific interaction in the compound eye of Drosophila has to be postulated. — The contrast dependence of the thrust response (Fig. 2) yields the acceptance angle of the receptors mediating the response. The result coincides with the acceptance angle found by analysis of the turning response of Drosophila (Heisenberg and Buchner, 1977). This value corresponds to the acceptance angle expected, on the basis of optical considerations, for the receptor system R 1–6. — The movement-specific neuronal network responsible for thrust control is not homogeneous throughout the visual field of Drosophila. Magnitude and preferred direction of the thrust response in the upper frontal part of the visual field seem to vary considerably in different flies (Fig. 6).     

Über die Cuticula von Platynereis dumerilii (Polychaeta)

Zusammenfassung Die Cuticula von Platynereis dumerilii liegt den Epidermiszellen auf. Ihre Matrix ist von zahlreichen, oberflächenparallelen, extrazellulären Fibrillenlagen durchzogen, die sich schichtweise kreuzen. In den Maschen dieser gekreuzten Fibrillenroste ziehen durchschnittlich 80 m weite Mikrovilli der Epidermiszellen bis in die Epicuticula. Die Oberfläche der Cuticula bildet Falten und ist von einer elektronendichten Cuticulamembran überzogen. Die Cuticula der Augenregion und des übrigen Körpers weist keine charakteristischen Unterschiede auf. — Die Bedeutung der Ultrastruktur der Cuticula für die Entstehung der beobachteten Interferenzfarben wird diskutiert.

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Summary The cuticle of Platynereis dumerilii covers the epidermal cells. Many sheets of extracellular, parallel fibers are embedded in the matrix of the cuticular layer. These sheets go parallel to the surface. The fiber run alternates from one sheet to the other. Microvilli of the epidermal cells measuring about 80 m in diameter extend through the meshes of the fiber grates up to the epicuticle. The surface of the cuticle is folded and covered by an electron-dense cuticle membrane. In the cuticle region covering the eye no corneal specializations are observed. — The structure of the cuticle is discussed with respect to the structural colours visible on the Platynereis body surface.

     

Wo beginnt bzw. wo endet der Biotop der Feldlerche?

Zusammenfassung Feldlerchen besiedeln innerhalb ihres Verbreitungsgebietes auch unabhängig von Bodentyp,-feuchtigkeit, -nutzung nicht Freiland schlechthin. Sie halten vielmehr proportional zu Flächengröße und vertikaler Höhe eines benachbarten Wald- oder des ihm gestaltmäßig äquivalenten Siedlungsgebietes einen bestimmten Trennabstand ein. Dieser Abstand beträgt in der nordwestdeutschen Kulturlandschaft (Raum Peine, Hannover—Braunschweig) durchschnittlich 160 m, maximal 220 m (gegenüber Waldungen und Siedlungen von mehr als 500 ha Größe), minimal 0 m (gegenüber Einzelbäumen oder Einzelgebäuden). Für das Biotopmuster Feld und dementsprechend die Biotopwahl der Feldlerche besitzen physiognomische Struktur und Flächengröße eines Raumes über dasde facto besiedelte Territorium hinaus Bedeutung.

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Summary Skylarks(Alauda arvensis) within their distribution range show a clear relation between the distance of their territories and the size and vertical height of adjacent woodlands or urban areas (Northwest Germany, around Peine, Hannover—Braunschweig). Open landper se, is not always occupied irrespective of edaphic or climatic factors. The limiting distance between the territories and the edges of adjacent woodlands and urban areas is 160 m in the average, with a maximum of 220 m (to woodland or urban areas over 500 ha size) and a minimum of 0 m (in an open landscape with scattered single trees or buildings). The physiognomy and size of adjacent areas thus influences the acceptability of open land, in other words, habitat selection in the Skylark involves features outside its territorial boundaries.

     

Requirements for in vitro propagation of seven nitrogen-fixing Alnus species

Studies on the in vitro propagation of Alnus crispa, A. glutinosa, A. incana, A. japonica, A. rubra, A. sinuata and A. viridis indicated interspecific as well as intraspecific variations in their requirements for in vitro culture. The WPM and Blaydes media supported, respectively, growth of A. glutinosa and A. crispa but not that of both species, while the MS medium induced equal or significantly better growth than WPM and Blaydes media for both species. The optimum type and concentration of sugar to be used in the multiplication medium varied with species. Only A. glutinosa showed good growth on sucrose while glucose was optimum for all other species but at different concentrations. All species rooted in 3 weeks on half-strength MS medium including 1 M IBA. All clones of A. glutinosa and A. rubra rooted 100%, whereas easy-to-root and difficult-to-root clones were observed in the other species. In the rooting medium, glucose promoted rooting of the difficult-to-root clones better than sucrose. Survival following transfer to an artificial substrate was 100% for all species. Nodulation tests using pure cultures of two Frankia strains showed 100% nodulation on all Alnus clones.     

Deducing the lateral distribution of proteins in lipid bilayer membranes

We consider four models of the lateral distribution of proteins in lipid bilayer membranes and study the fraction of lipids which are adjacent to at least one protein (adjacent lipids) and how this quantity depends upon protein concentration. The models are (i) hard hexagons free to move from one lattice site to another; (ii) hard disks moving on a continuum; (iii) a mixture of two sizes of nearly-hard disks moving on a continuum; (iv) a modification of (ii). The hexagons or disks represent proteins, while unocupied lattice sites or the remainder of the continuum represents lipids. In (iii) large disks represent proteins and small disks represent lipids. In (iv) some of the continuum between pairs of disks, where packing defects might occur, is not occupied by lipids. We find that an analytical expression for the adjacent lipids (Hoffmann et al. 1981), which is in excellent agreement with the results of the Hexagon model (i), breaks down at a packing density of f _A0.805, and we show by considering the hexagon pair correlation function, that this indicates the onset of random close packing, and that a transition to ordered close packing occurs at f _A=0.866. We thus obtain an operational definition for a random distribution of hexagons: distributions of packing densities0.805. We show that the Disk model (ii) gives results for adjacent lipids that are greater than the Hexagon model and compare these results to the Two Disk model (iii) which gives a result substantially less than the Hexagon model (Mountain et al. 1986). We show that the Modified Disk model (iv) gives results in essential agreement with the Hexagon model except for f _A0.77. Finally we discuss the general appearance of the motion restricted ESR spectrum and conclude that, of these four models, the Modified Disk or the Hexagon models best account for the data. We discuss why this is so with reference to the representation of a 3-dimensional membrane by a 2-dimensional plane.Abbreviations ESR Electron Spin Resonance     

Das Auge von Platynereis dumerilii (Polychaeta) Sein Feinbau im ontogenetischen und adaptiven Wandel

Zusammenfassung Der Feinbau des Auges von Platynereis dumerilii wurde auf drei Entwicklungsstadien untersucht: beim Jungwurm, beim ausgewachsenen atoken und beim epitoken Wurm.Das Juvenilauge besteht aus zwei Sehzellen mit Receptorkeulen und aus zwei Pigmentbecherzellen, welche den Pigmentbecher und die Füllmasse bilden.Im ausgewachsenen Auge entsprechen den Pigmentbecherzellen des Juvenilauges die Stützzellen. Cytoplasmatische Fortsätze der Stützzellen bilden im Augeninnern die Füllmasse (Linse); sie bleiben mit den Leibern der Stützzellen durch schmale Cytoplasmatische Säulen verbunden, welche den Receptorsaum durchqueren. Die Stützzellen werden der Länge nach von Stützfibrillen durchzogen. — Die Receptorkeule (Stäbchen) der Sehzelle ist mit vielen unregelmäßig angeordneten Mikrovilli besetzt und enthält Vesikel, paarige Membranen und ein Basalkorn mit einer Wimperwurzel. — Der Becher aus Stützzellpigment wird von Pigmentgranula in den Sehzellen vervollständigt.Die epidermale Umgebung des Auges wird beschrieben; sie ist frei von Interzellularlücken.Die Pupillenregionen hell- und dunkel-adaptierter Tiere werden miteinander verglichen. Mögliche Mechanismen des Pupillenspiels werden diskutiert.

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Summary The fine structure of the eye of Platynereis dumerilii was examined in the juvenile worm, in the atokal adult, and in the epitokal polychaete.The juvenile eye consists of two visual cells with receptor clubs and of two pigment cells forming the Füllmasse and the pigment cup.In the adult worm the supporting cells correspond to the pigment cells in the juvenile eye. The central processes of the supporting cells build up the Füllmasse (lens); they remain connected with the supporting cells by narrow cytoplasmic stalks which pass the photoreceptor region. Fibrils run through the entire length of the supporting cells. — The receptor club (rod) of the visual cell shows irregularly arranged microvilli; it contains vesicles and paired membranes and a basal body with a striated rootlet. — The pigment granules of both visual and supporting cells form the pigment cup of the eye.The epidermal surroundings of the eye are described, there are no intercellular gaps.The pupillar region of light and dark-adapted specimens was examined and the kinetics of pupillar movements are discussed.

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Herrn Prof. Dr. W. Bakgrann zum 60. Geburtstag gewidmet. — Die Untersuchung wurde mit dankenswerter Hilfe der Deutschen Forschungsgemeinschaft durchgeführt.     

Fermenttopochemische Untersuchungen an der Nebennierenrinde des Meerschweinchens nach Abschluss einer langfristigen Cortisonvorbehandlung

Zusammenfassung Das histotopochemische Verhalten verschiedener Fermente wurde an der Nebenniere von 28 Tage lang mit Cortison vorbehandelten Meerschweinchen untersucht.Es findet sich bei allen beobachteten Fermenten mit Ausnahme der DPN-Diaphorase zum Zeitpunkt des Absetzens der Vorbehandlung ein Aktivitätsabfall in der Zona Fasciculata. In der Zona Glomerulosa war nur bei den sauren Phosphatasen, der Glucose-6-phosphatdehydrogenase und der 3-ol-Steroiddehydrogenase eine Verminderung der Aktivität festzustellen.Die Normalaktivität wurde von den einzelnen Fermenten nach verschieden langen Zeiträumen wieder erreicht. Bei 3-ol-Steroiddehydrogenase, Glucose-6-phosphatdehydrogenase und den alkalischen Phosphatasen tritt dabei ein rebound auf.Zwischen den gefundenen Fermentveränderungen und dem Verhalten der Kernvolumina und der 17-OHCS-Ausscheidungskurve in der Restitutionsphase bestehen Zusammenhänge, die diskutiert werden.

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Summary The histotopochemical distribution of various enzymes is studied in the adrenal cortex of Guinea-pigs after a 28 days administration of cortisone.All the enzymes investigated show a decrease of enzymatic activity in the zona fasciculata directly after the administration of cortisone has ceased. In the zona glomerulosa only acid phosphatases, glucose-6-phosphatedehydrogenase and 3-ol-steroiddehydrogenase show a decrease of activity. The enzymes concerned reached normal activity after different periods. A rebound was noted with 3-ol-steroiddehydrogenase, glucose-6-phosphatedehydrogenase and alkaline phosphatases.The relations between the changes in the enzymatic activity, the reaction of the nuclear volumes and the 17-OHCS-excretion curve in the restoration period are discussed.

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Mit Unterstützung durch die Deutsche Forschungsgemeinschaft.

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Ausgeführt unter Leitung von Priv.-Doz. Dr. M. Herrmann.     

Der hemmende Einfluß gleichzeitig bewegter Beuteattrappen auf das Beutefangverhalten der Erdkröte (Bufo bufo L.)

Zusammenfassung Durch simultane visuelle Bewegungsreize, die von mehreren Beutetieren (z.B. Mehlkäferlarven) ausgehen, wird der Beutefang der Erdkröte (Bufo bufo L.) gehemmt. An diese Verhaltensheobaehtung anknüpfend, wurde die Abhängigkeit dieses inhibitorischen Umfeldeffektes von verschiedenen visuellen Reizparametern im Attrappen versuch quantitativ gemessen: Im frontalen Gesichtsfeld der Kröte rotierte vor dunklem Hintergrund eine weiße, rechteckige, 2,5 × 20° große Beuteattrappe (Zentralattrappe, z) mit dem Rechteckzentrum im Drehpunkt. Zusätzlich konnten mehrere Kreisscheiben von 5 bzw. 10° (Peripherattrappen, p) um die Zentralattrappe bewegt werden.Die Beutefangaktivität R _z [Beutefangreaktionen x min^–1] auf die allein gebotene Zentralattrappe war bei einer Sehwinkelgeschwindigkeit v _s der distalen Attrappenkanten 10v _s30 [grad x see^–1] maximal und sank für kleinere oder größere Winkelgeschwindigkeiten wieder ab. Eine mit v _s=25 [grad x sec^–1] allein bewegte Peripherattrappe löste maximale Beutefangaktivität R _p aus. Mit zunehmender Anzahl n _p simultan bewegter Peripherattrappen sank die Beutefangaktivität ab.Mehrere, um den gleichen Drehpunkt bewegte Peripherattrappen, deren Abstand untereinander =10° betrug, blieben von der Kröte unbeantwortet. Sie bildeten ein inhibitorisches Umfeld und hemmten dadurch die Reaktion auf die gleichzeitig bewegte Zentralattrappe z. — Die im Simultanreizungsversuch gemessene Beutefangaktivität R _zp war abhängig vom Abstand [grad] zwischen Zentralattrappe und Peripherattrappen ( : Kürzester Abstand zwischen z und p): Für =10° war R _zp0 und stieg für >10° an. — Kontrollversuche, die jeweils auf die Simultanreizung mit z allein folgten (R _z), ließen eine -abhängige Nachhemmung erkennen. — Die hemmende Wirkung auf die Beantwortung von z war auch von der Sehwinkelgeschwindigkeit v _s der Peripherattrappen abhängig; sie war bei derjenigen Sehwinkelgeschwindigkeit (v _s=25 [grad × sec^–1]) maximal, mit der die Zentralattrappe, allein geboten, maximale Beutefangaktivität auslöste; für v _sg25 [grad × sec^–1] nahm die Hemmung wieder ab.Die Versuchsergebnisse lassen auf inhibitorische Verknüpfungen innerhalb des zentralen visuellen Systems schließen. Es wird vermutet, daß die Reiz-Verhaltens-reaktionsbeziehungen in den visuellen Simultanreizungsversuchen durch eine Art zentrale laterale Inhibition bestimmt werden.

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Inhibitory effect of simultaneously moved prey dummies on the prey catching behaviour of the common toad (Bufo bufo L.)

Summary The prey catching behaviour of the toad (Bufo bufo L.) is generally inhibited by simultaneously visual moving stimuli caused by a group of prey animals (mealworms). According to this behavioural observation the dependence of this inhibitory effect on several visual parameters were quantitatively measured in dummy experiments: in the frontal visual field of the toad a white rectangular prey dummy of 2,5×20° (central dummy, z) was rotating in a centre against dark background. In addition several disks of 5 or 10° diameter (peripheral dummies, p) could simultaneously rotate around the central dummy (Figs. 1 and 7).The prey catching activity R _z [catching reactions x min^–1] released by rotation of only the central dummy z increased with increasing angular velocity v _s of the stimulus distal edges, reaching a maximum for 10v_s30 [degrees x sec^–1] and decreasing for v _s>30 [degrees x sec^–1] (Fig. 5).A single peripheral dummy p, moved at v _s=25 [degrees x sec^–1], released maximal catching activity R _p. The activity R _p decreased with the increasing number n _p of simultaneously offered dummies (Fig. 6).The prey catching behaviour of the toad was inhibited, when several peripheral dummies p were moved around the centre with a distance =10° from each other. They caused an inhibitory field and they also inhibited the response to a simultaneously moved central dummy z. The prey catching activity, measured in experiments in which z and p rotated simultaneously, depends on the distance [degrees] between z and p ( being the shortest distance between z and p). For =10°, R _zp was zero; R _zp increased for >10° (Figs. 9 and 10). — Control experiments carried out with z allone — after having applied the simultaneous stimulation — showed a - dependent after-inhibition (Fig. 9). — The inhibitory effect on the response to z also depended on the angular velocity v _s of p; the inhibition was at a maximum for v _s25 [degrees x sec^–1], and it decreased for v _s25 [degrees x sec^–1] (Fig. 11).The experimental results suggest inhibitory interactions within the central visual system. It is supposed that the relation between stimulus and behavioural reaction in simultaneous stimulating experiments results from some kind of central nervous lateral inhibition.

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Mit Unterstützung der Deutschen Forschungsgemeinschaft (Ew 7/4+5).