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  • 1
    Electronic Resource
    Electronic Resource
    Larva-adult relationships in an ancestral dipteran: A re-examination of sensillar pathways across the antenna and leg anlagen of Chaoborus crystallinus (DeGeer, 1776; Chaoboridae) (1999)
    Springer
    Development genes and evolution 209 (1999), S. 103-112 
    Details
    ISSN: 1432-041X
    Keywords: Key words Imaginal disc ; Axonal trajectories ; Ultrastructure ; Chaoborus (Insecta ; Diptera)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  In one of his classical studies on insect metamorphosis, Weismann compared the imaginal anlagen of the ancestral phantom midge, Chaoborus, with those of advanced brachycerans. We have expanded his findings on the relationships between larval and imaginal organs using electron microscopy and cobalt backfilling of the antenna and leg anlagen and the axonal trajectories of corresponding larval sensilla. We show that both primordia are confluent with the larval antennae and ”leg” sensilla (an ancestral Keilin organ), respectively. These fully developed larval organs represent the distal tips of the imaginal anlagen rather than separate cell clusters. The axons of the larval antenna and leg sensilla project across the corresponding anlagen to their target neuromeres within the central nervous system (CNS). Within the discs, nerves composed of these larval axons, developing afferent fibres and efferences ascending from the CNS are found. Both the structure of the primordia and the axonal trajectories thus relate the situation found in advanced brachycerans with that seen in more ancestral insects. In addition, the larval antennae, legs, wings and even the eyes possess very similar afferent pioneer trajectories supporting the idea that the described pattern is generally used in the ontogeny of sensory systems.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004270050232
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  • 2
    Electronic Resource
    Electronic Resource
    Fly rhabdomeres twist in vivo (1981)
    Springer
    Journal of comparative physiology 142 (1981), S. 43-49 
    Details
    ISSN: 1432-1351
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Electron-microscopic examination shows that the rhabdomeres of the visual cells ofMusca domestica twist in the manner typical ofCalliphora erythrocephala andDrosophila melanogaster. More-over, it can be demonstrated that the rhabdomere section shown by Ribi (1979, Fig. 2) is from a twisting rhabdomere. Rhabdomere twist appears to be a wide-spread feature of dipteran eyes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00605474
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  • 3
    Electronic Resource
    Electronic Resource
    Untersuchung zur Topographie, Mechanik und Strömungsmechanik der Sinneshaare auf dem Kopf der Wanderheuschrecke Locusta migratoria (1970)
    Springer
    Journal of comparative physiology 67 (1970), S. 382-402 
    Details
    ISSN: 1432-1351
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Zusammenfassung 1. Auf dem Kopf von Locusta befinden sich durchschnittlich 430 windempfindliche Haare. 2. Die Längen aller Haare verteilen sich recht gut auf drei Gruppen: 1.1〈150 μm (im Mittel 76%), 2. 150≦1〈230 μm (17%), 3. 1≧230 μm (7%). 3. Die Mechanik des Haarsockels wird an Lebendschnitten mit intaktem Sockelapparat untersucht. Der Haarschaft wird oberhalb der Gelenkmembran von einer Manschette umfaßt. Bei einer Auslenkung des Haares wird der Schaft um die als allseitigen Anschlag wirkende Manschette gekippt; die Gelenkmembran verhält sich dabei wie ein elastisches Band mit geringer Federkonstante. Eine Verformung des Schaftes im Bereich des Sockels läßt sich nicht beobachten. 4. Die bei konstanten Auslenkungen des Haares auftretenden rücktreibenden Kräfte sind von der Richtung unabhängig. 5. Die Auslenkung eines Haares ist vom lokalen Strömungsfeld abhängig; die Auslenkung ist sowohl von der Haarlänge und der Windgeschwindigkeit als auch von der Windrichtung und dem Standort des Haares auf dem Kopf abhängig. 6. Die Ausbildung von örtlichen Auslenk- und Erregungsmustern in Abhängigkeit von der Windrichtung und -geschwindigkeit und ihre mögliche Bedeutung für die Heuschrecke werden diskutiert.
    Notes: Summary 1. Approximately 430 wind-sensitive hairs are found on the head of Locusta. 2. Hair-length-distribution can be satisfactorily divided into three classes: 1. 1〈150 μm (∼76%), 2. 150≦1〈230 μm (∼17%), 3. 1≧230 μm (∼7%). 3. The mechanics of the hair-socket was examined in unfixed sections of the cuticle. The cutting left the sensillum uninjured. The socket wall surrounds the hair on all sides like a close-fitting sleeve. When deflected to any side, the hair engages the sleeve as a fulcrum. The membrane joining the hair with cuticle then behaves as an elastic band easily stretched. No deformation of the hair in the neighbourhood of the socket was observed. 4. Elastic forces generated by deflecting the hair are constant for the same degree of deflection no matter what its direction. 5. When a jet of air is directed at the head of Locusta, the extent of deflection of a hair depends upon the local air current field at the hair; that is, besides hair length and air speed, the degree of deflection depends on the angle of the air stream with the head and on the shape of the head at and near the hair. 6. The effect of air speed and direction on the generation of deflection patterns of the hairs across the head and their corresponding impulse sequences is discussed along with the possible significance of the patterns for the locust.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00297907
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  • 4
    Electronic Resource
    Electronic Resource
    Rezeptor- und Aktionspotentiale der Sinneshaare auf dem Kopf der Wanderheuschrecke Locusta migratoria (1970)
    Springer
    Journal of comparative physiology 70 (1970), S. 335-348 
    Details
    ISSN: 1432-1351
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Zusammenfassung 1. Von den Sensillen werden Rezeptor- und Aktionspotentiale mit Wolfram- und Kapillarelektroden abgeleitet. Die Sensillen werden durch sprungförmige Auslenkungen der Haarschäfte gereizt. 2. Das Rezeptorpotential und die Impulsrate werden im stationären Zustand in Abhängigkeit vom Grad und der Richtung der Auslenkung sowie von der Temperatur gemessen. 3. Die Kennlinie des Sensillums läßt sich in einen Anlaufbereich (Auslenkung α〈3°), einen Arbeitsbereich (3° = α〈12,6°) und einen Sättigungsbereich (α = 12,6°) einteilen. Der auf die Potentialhöhe im Sättigungsbereich bezogene relative Übertragungsfaktor beträgt im Anlaufbereich V rel = 2,1% pro Grad Auslenkung, im Arbeitsbereich V rel = 9,6 % pro Grad Auslenkung. 4. Das Richtdiagramm des Sensillums besitzt einen Halbwerts-Öffnungswinkel von ω=162°. Eine von Nicklaus (1965) bei Periplaneta gefundene richtungsabhängige Hyperpolarisation der Sinneszellmembran tritt bei Locusta nicht auf. 5. Die Impulsrate ist direkt proportional zur Temperatur. Die differentielle Temperaturempfindlichkeit beträgt für die stationäre Impulsrate E ϑ=6,5 Imp/ Grad C; für die unmittelbar nach Beizbeginn gemessene Impulsrate steigt sie auf E ϑ = 51,3 Imp/Grad C an. 6. Die stationären Eigenschaften der Sensillen werden mit denen der Borstenfeld-Sensillen bei Apis (Thurm, 1963, 1964) und der Fadenhaare bei Periplaneta (Nicklaus, 1965) verglichen und diskutiert.
    Notes: Summary 1. Receptor and action potentials were recorded from hair-sensilla of Locusta by means of tungsten electrodes and glass capillaries. Sensilla were excited by steplike deflections of the hair shaft. 2. Receptor potentials and impulse frequency were measured in relation to degree and direction of deflection and also to temperature. 3. The static characteristic curve of the sensilla is divided into three regions: initial region (deflection α 〈 3°), linear region (3°≦α〈12.6°) and saturation region (α≧12.6°). The slope of the initial region amounts to V rel = 2.1, the slope of the linear region to V rel = 9.6% of magnitude in the saturation region per degree deflection. 4. The half-magnitude angle of the directional characteristic diagramm of the sensilla is ω = 162°. Direction-controlled hyperpolarization as Nicklaus (1965) found in Periplaneta was not detected in Locusta. 5. The impulse rate is directly proportional to temperature. Incremental temperature sensitivity of the static impulse rate amounts to E ϑ = 6.5 Imp/ degree C; for the peak impulse rate measured almost immediately after deflection it rises to E ϑ = 51.3 Imp/degree C. 6. Static characteristics of hair-sensilla are compared with those of filiform hairs of Periplaneta (Nicklaus, 1965) and hair-plate sensilla of Apis (Thurm, 1963, 1964).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00297753
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  • 5
    Electronic Resource
    Electronic Resource
    Electrophysiological measurements of spectral sensitivity of central visual cells in eye of blowfly (1976)
    [s.l.] : Nature Publishing Group
    Nature 260 (1976), S. 342-344 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Measurements by electrophysiological methods have given rise to double-peaked sensitivity curves1-3, all having in common a maximum in the ultraviolet range at 350 nm. The other peaks occurred at different wavelengths in the visible range of the spectrum. According to the positions of these maxima ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/260342a0
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  • 6
    Electronic Resource
    Electronic Resource
    Regional differences in a nematoceran retina (Insecta, Diptera) (1985)
    Springer
    Zoomorphology 105 (1985), S. 99-107 
    Details
    ISSN: 1432-234X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The compound eye of Psychoda cinerea comprises two types of ommatidia, arranged so as to divide the retina into distinct dorsal and ventral regions. The P-type ommatidium, in the ventral part of the eye, differs fundamentally from the other dipteran ommatidia so far described, and is regarded as a primitive ommatidium. The acone dioptric apparatus is the same in both types, with a spherical lens and four Semper cells, the processes of which expand below the rhabdom to form a ring of pigment sacs. Only the distal region of the rhabdom is surrounded by a continuous ring of screening pigment, formed by 2 primary and 12–16 secondary pigment cells. The highly pigmented retinula cells penetrate the basement membrane proximally at about the level of their nuclei; in this region they are separated from the hemolymph by glial elements. The rhabdomeres R1–6 are fused to form a tube. The two types of ommatidia are defined by the arrangement of the retinula cells R7/8: in the T type the central rhabdomeres are one below the other, in the usual tandem position, whereas in the P type only R8 is central, with R7 in the peripheral ring. In the proximal region of the retina, retinula cells with parallel microvilli in neighboring ommatidia are joined in rows by lateral processes from the R8 cells. All the rhabdomeres are short and not twisted, which suggests that the retinula cells are highly sensitive to direction of polarization. The eye can adapt by a number of retinomotor processes. These findings, together with observations of behavior, imply that the psychodids have well-developed visual abilities.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00312144
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  • 7
    Electronic Resource
    Electronic Resource
    Compound Eye Evolution: Highly Conserved Retinula and Cone Cell Patterns Indicate a Common Origin of the Insect and Crustacean Ommatidium (1997)
    Springer
    Naturwissenschaften 84 (1997), S. 542-544 
    Details
    ISSN: 1432-1904
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Natural Sciences in General
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001140050442
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  • 8
    Electronic Resource
    Electronic Resource
    Evolution of Small Sense Organs: Sensilla on the Larval Antennae Traced Back to the Origin of the Diptera (1998)
    Springer
    Naturwissenschaften 85 (1998), S. 501-505 
    Details
    ISSN: 1432-1904
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Natural Sciences in General
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001140050539
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  • 9
    Electronic Resource
    Electronic Resource
    Walking on insect paths? Early ommatidial development in the compound eye of the ancestral crustacean, Triops cancriformis (2000)
    Springer
    Naturwissenschaften 87 (2000), S. 308-311 
    Details
    ISSN: 1432-1904
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Natural Sciences in General
    Notes: Abstract  Ommatidia (the compound eye's functional units) in insects are formed by the recruitment of undifferentiated cells under the control of signalling factors. During this process, a sequence of "preclusters" composed of specifically arranged precursor cells is followed. In the growth zone of the eye of Triops, an ancestral crustacean, we observed a patterning process that corresponds well with that of insects. In both taxa, clusters with arc-like, five-cell and eight-cell patterns are found, and the sequence in which the photoreceptor or R-cells of each ommatidium become identifiable is basically the same. The first to appear are R8-like and R2/5-like cells, second are R3/4-like, and third are R1/6- and R7-like cells (if the fly's cell-numbering system is used). Thus, the morphogenetic steps during which the cell identities and the cellular architecture of the ommatidia develop appear to be conserved between these arthropod groups. Furthermore, the individual cells and cell pairs which build an insect ommatidium seem to have their homologues in crustaceans. In the evolution of developmental processes, intercellular recruitment seems to be a mechanism operating on the level of single cells even in distantly related species.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001140050727
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  • 10
    Electronic Resource
    Electronic Resource
    Central projections of Tömösváry’s organ in Lithobius forficatus (Chilopoda, Lithobiidae) (1996)
    Springer
    Cell & tissue research 283 (1996), S. 331-334 
    Details
    ISSN: 1432-0878
    Keywords: Key words: Tömösváry’s organ ; Sensilla ; Sensory projections ; Protocerebrum ; Lithobius forficatus (Antennata ; Opisthogoneata)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. Afferents of Tömösváry’s organ innervate multiple synaptic sites within the ipsilateral protocerebrum, i.e. neuropil areas proximal to the 2nd optic neuropil, in the dorsolateral protocerebrum, and surrounding the pedunculus of the ”mushroom bodies”. Sensory input via Tömösváry’s organ in Lithobius appears to follow a peculiar neuronal pathway bypassing the deutocerebrum and tritocerebrum which are innervated by many head sensilla in arthropods.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004410050543
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