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  • 1
    Electronic Resource
    Electronic Resource
    Biomechanics Turning the key on Drosophila audition (2001)
    [s.l.] : Nature Publishing Group
    Nature 411 (2001), S. 908-908 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] The genetic dissection of Drosophila audition is advancing considerably, but complementary studies are needed to unravel the chain of mechanosensory events that bring about hearing in the fly. Here we investigate the delicate biomechanics of the fly's minute antennal hearing organs and show ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/35082144
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  • 2
    Electronic Resource
    Electronic Resource
    Compensatory head rolling during corrective flight steering in locusts (1990)
    Springer
    Journal of comparative physiology 166 (1990), S. 685-693 
    Details
    ISSN: 1432-1351
    Keywords: Locust ; Flight steering ; Optomotor response ; Compensatory head movement
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary 1. Locusts (Locusta migratoria) flying under open-loop conditions respond to simulated course deviations (movements of an artificial horizon around the roll axis) with compensatory head movements and with steering reactions of wing muscles (Figs. 3, 4). Steering was quantified as shifts of the relative latency between spikes in the left and right M97 (first basalar muscle). For practical reasons these shifts are a more useful measure than corrective torque itself, to which they are linearly proportional over much of the range (Fig. 2). 2. Steering in M97 is elicited visually (horizon movement) and by proprioceptive input reporting head movements (neck reflexes). Compensatory head movements reduce the strength of steering because the reduction in visual information signalling deviations is only partially balanced by proprioceptive input from the neck (Fig. 4C). 3. Under closed-loop conditions, flying locusts stabilize the position of an artificial horizon against a constant bias (Figs. 5–7), the horizon oscillating slightly along the normal orientation. Head movements do not follow the horizon movements as closely as under open-loop conditions, but on average head movements are compensatory, i.e. the mean mismatch between head and horizon is less than the mean mismatch between body and horizon. 4. The horizon position is stabilized when the head is free to move, but also when the head is immobilized. In the latter case the oscillations along the straight flight path are more pronounced (Fig. 7), indicating that the reduction of steering by compensatory head movements (as seen under open-loop conditions, Fig. 4C) reduces overshoot. 5. The control and the significance of (compensatory) head movements for course control are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00240018
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  • 3
    Electronic Resource
    Electronic Resource
    Visual steering under closed-loop conditions by flying locusts: flexibility of optomotor response and mechanisms of correctional steering (1988)
    Springer
    Journal of comparative physiology 164 (1988), S. 15-24 
    Details
    ISSN: 1432-1351
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary 1. Tethered locusts,Locusta migratoria, flying in a laminar air flow react to motion of the visual world with compensatory steering. 2. Vertical gratings surrounding the animal and rotating around the yaw axis elicit an optomotor yaw response. At the low light level used, gratings of spatial periods (λ) below 10° or of contrast frequency (CF) above 15 Hz are less effective. 3. In a flight simulator which converts torque into angular velocity of the vertical grating, the locust can control the motion of its visual surroundings. When the negative feedback loop is closed, locusts stabilize a vertical grating by modulation of their yaw torque. This indicates that the correctional steering behaviour described under open loop conditions is functionally relevant. 4. Under the same conditions, the optomotor reactions lead to the stabilization of a single vertical stripe in the frontal visual area (fixation). 5. With positive feedback (i.e. the pattern turns in the same direction as the torque), no corresponding inversion of steering is observed, and stabilization around the yaw axis fails. 6. Under similar negative feedback conditions, locusts stabilize the position of the visual horizon around the roll axis by modulating their roll torque. Positive feedback leads, however, to the stabilization of the horizon in the inverted position (reverse albedo). 7. The results suggest the existence of two steering strategies, one based on the parameters of visual movement and the other on position in the visual field and relative luminance. The use of these strategies is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00612713
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  • 4
    Electronic Resource
    Electronic Resource
    The histological architecture of the auditory organs in the parasitoid fly Ormia ochracea (2000)
    Springer
    Cell & tissue research 301 (2000), S. 447-457 
    Details
    ISSN: 1432-0878
    Keywords: Acoustic parasitism Insect hearing Mechanoreception Chordotonal organ 3-D reconstruction Scolopales Attachment cells Diptera Ormia ochracea (Insecta)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. Gravid females of the parasitoid fly species Ormia ochracea (Diptera: Tachinidae) rely on their sense of hearing to detect and localize their hosts, field crickets of the genus Gryllus. As in any hearing insect species, the fly's auditory system consists of a rather complex cascade of mechanical and physiological mechanisms, starting with the conversion of the acoustic energy in the sound field into mechanical vibrations that, in turn, are sensed in the auditory sensory organs by multicellular mechanoreceptive units – the scolopidia. This article reports on the histological architecture of the sensory organs using conventional histological serial sections and their three-dimensional reconstructions, and confocal laser microscopy. The scolopidia's spatial distribution and the three-dimensional organization of the actin-containing attachment cells are described. Morphometric measurements show that individual scolopales vary in their size and shape. Pronounced intersexual differences have been previously shown to exist in auditory function, in particular with respect to frequency sensitivity, peripheral auditory anatomy, and notably behavior. The present results show that intersexual differences in the histoarchitecture of the sensory organs are small. Results are compared with some other insect auditory systems and are also discussed in terms of their significance for frequency sensitivity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004410000257
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  • 5
    Electronic Resource
    Electronic Resource
    The tympanal hearing organ of a fly: phylogenetic analysis of its morphological origins (1995)
    Springer
    Cell & tissue research 282 (1995), S. 251-268 
    Details
    ISSN: 1432-0878
    Keywords: Key words: Chordotonal organ ; Tracheal system morphology ; Parasitoid Tachinidae ; Ormia ochracea ; Myiopharus doryphorae ; Eurosta solidaginis ; Neobellieria bullata (Insecta)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. A key adaptation for any parasitoid insect is the sensory modality that it uses to locate its host insect. All members of the speciose family Tachinidae (Diptera) are parasitoids, but only flies of the tribe Ormiini use acoustic cues to find their hosts. Ormiine flies are para-sitoids of various genera of crickets and katydids. Gravid females of one ormiine species, Ormia ochracea, hear the reproductive calling song of male field crickets and home in on those calls to locate their hosts. While many flies possess various kinds of ”ears” to detect airborne sounds, only ormiine flies have been reported to possess true tympanal hearing organs. Such organs are well-known to occur in their cricket and katydid hosts. The ormiine ear is an evolutionary innovation within Diptera. Our objective was to trace the phylogenetic origins of the tympanal hearing organ among higher flies. Since the ormiine hearing organ is a complex organ within the prothorax, we examined possible precursor structures in the prothoraces of selected Diptera. We have uncovered a suite of characters that define the ormiine ear. These characters in the prothorax include a pair of prosternal tympanal membranes, a pair of chordotonal sensory organs, and modifications of the tracheal system. We have been able to identify and trace the presumptive homologs of these ormiine characters through selected species of related Diptera, using the method of outgroup comparison.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004410050477
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  • 6
    Electronic Resource
    Electronic Resource
    The tympanal hearing organ of a fly: phylogenetic analysis of its morphological origins (1995)
    Springer
    Cell & tissue research 282 (1995), S. 251-268 
    Details
    ISSN: 1432-0878
    Keywords: Chordotonal organ ; Tracheal system morphology ; Parasitoid Tachinidae ; Ormia ochracea ; Mytopharus doryphorae ; Eurosta solidaginis ; Neobellieria bullata (Insecta)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract A key adaptation for any parasitoid insect is the sensory modality that it uses to locate its host insect. All members of the speciose family Tachinidae (Diptera) are parasitoids, but only flies of the tribe Orminini use acoustic cues to find their hosts. Ormiine flies are parasitoids of various genera of crickets and katydids. Gravid females of one ormiine species, Ormia ochracea, hear the reproductive calling song of male field crickets and home in on those calls to locate their hosts. While many flies possess various kinds of “ears” to detect airborne sounds, only ormiine flies have been reported to possess true tympanal hearing organs. Such organs are wellknown to occur in their cricket and katydid hosts. The ormiine ear is an evolutionary innovation within Diptera. Our objective was to trace the phylogenetic origins of the tympanal hearing organ among higher flies. Since the ormiine hearing organ is a complex organ within the prothorax, we examined possible precursor structures in the prothoraces of selected Diptera. We have uncovered a suite of characters that define the ormiine ear. These characters in the prothorax include a pair of prosternal tympanal membranes, a pair of chordotonal sensory organs, and modifications of the tracheal system. We have been able to identify and trace the presumptive homologs of these ormiine characters through selected species of related Diptera, using the method of outgroup comparison.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00319116
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  • 7
    Electronic Resource
    Electronic Resource
    RNA in the nucleus of a motile plant spermatozoid: Characterization by enzyme-gold cytochemistry and in situ hybridization (1988)
    New York, NY [u.a.] : Wiley-Blackwell
    Molecular Reproduction and Development 1 (1988), S. 49-56 
    Details
    ISSN: 1040-452X
    Keywords: mRNA ; Differentiation ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: To investigate the decrease of transcription and to determine the localization of RNA molecules during spermiogenesis in the fern Scolopendrium, we have used the enzyme-gold electron microscope method. During cell differentiation, the labeling decreases over the cytoplasm and increases over the nucleus. In the latter, the nucleolus disappears at the beginning of differentiation and the gold particles that were at first situated over the dispersed chromatin are then located over the condensed chromatin. In mature gametes, gold particles linked to RNA are abundant over the dense and homogeneous nucleus and sparse over the cytoplasm. By using in situ hybridization of RNA-poly(A) tails with radioactive poly(U) probes, we have shown that these RNA molecules are mRNA; they are located in the condensed chromatin of the mature sperm nucleus.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1080010108
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  • 8
    Electronic Resource
    Electronic Resource
    Structural organization of the sperm chromatin in a fern (Scolopendrium vulgare) studied by spreading methods (1987)
    New York, NY : Wiley-Blackwell
    Gamete Research 17 (1987), S. 21-33 
    Details
    ISSN: 0148-7280
    Keywords: spermatozoid; nucleus; beaded ; smooth ; knobby fibers ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: To investigate chromatin organization, we applied the spreading techniques to nuclei isolated from Scolopendrium spermatozoids.Well-dispersed chromatin shows three types of fibers: beaded fibers corresponding to a nucleosomal filament with adjacent nucleosomes in close contact, smooth fibers (14 nm in diameter) associated in a complex network, and knobby fibers constituted by local supercoiling of a very thin (4 nm) smooth filament. Along the knobby fibers, beads of variable size are irregularly spaced.The knobby fibers lie parallel and coalesce in thick bundles. The sperms basic proteins identified by electrophoretic analysis probably promote the supercoiling and the side-to-side attachment of the knobby fibers, which are all the more abundant in spread preparations. These results indicate that knobby fibers are probably located in the outer part of the sperm nucleus in which the chromatin is densely packed. As for the nucleosomal and smooth filaments, they may be situated in the inner part.
    Additional Material: 17 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1120170104
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  • 9
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    Biomechanics of a moth scale at ultrasonic frequencies (2018)
    National Academy of Sciences
    Details
    Publication Date: 2018-11-12
    Description: The wings of moths and butterflies are densely covered in scales that exhibit intricate shapes and sculptured nanostructures. While certain butterfly scales create nanoscale photonic effects, moth scales show different nanostructures suggesting different functionality. Here we investigate moth-scale vibrodynamics to understand their role in creating acoustic camouflage against bat echolocation, where scales on wings provide ultrasound absorber functionality. For this, individual scales can be considered as building blocks with adapted biomechanical properties at ultrasonic frequencies. The 3D nanostructure of a full Bunaea alcinoe moth forewing scale was characterized using confocal microscopy. Structurally, this scale is double layered and endowed with different perforation rates on the upper and lower laminae, which are interconnected by trabeculae pillars. From these observations a parameterized model of the scale’s nanostructure was formed and its effective elastic stiffness matrix extracted. Macroscale numerical modeling of scale vibrodynamics showed close qualitative and quantitative agreement with scanning laser Doppler vibrometry measurement of this scale’s oscillations, suggesting that the governing biomechanics have been captured accurately. Importantly, this scale of B. alcinoe exhibits its first three resonances in the typical echolocation frequency range of bats, suggesting it has evolved as a resonant absorber. Damping coefficients of the moth-scale resonator and ultrasonic absorption of a scaled wing were estimated using numerical modeling. The calculated absorption coefficient of 0.50 agrees with the published maximum acoustic effect of wing scaling. Understanding scale vibroacoustic behavior helps create macroscopic structures with the capacity for broadband acoustic camouflage.
    Print ISSN: 0027-8424
    Electronic ISSN: 1091-6490
    Topics: Biology , Medicine , Natural Sciences in General
    Published by National Academy of Sciences
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  • 10
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    Mechanism for rapid passive-dynamic prey capture in a pitcher plant (2015)
    National Academy of Sciences
    Details
    Publication Date: 2015-10-05
    Description: Plants use rapid movements to disperse seed, spores, or pollen and catch animal prey. Most rapid-release mechanisms only work once and, if repeatable, regaining the prerelease state is a slow and costly process. We present an encompassing mechanism for a rapid, repeatable, passive-dynamic motion used by a carnivorous pitcher plant to catch prey. Nepenthes gracilis uses the impact of rain drops to catapult insects from the underside of the canopy-like pitcher lid into the fluid-filled trap below. High-speed video and laser vibrometry revealed that the lid acts as a torsional spring system, driven by rain drops. During the initial downstroke, the tip of the lid reached peak velocities similar to fast animal motions and an order of magnitude faster than the snap traps of Venus flytraps and catapulting tentacles of the sundew Drosera glanduligera. In contrast to these active movements, the N. gracilis lid oscillation requires neither mechanical preloading nor metabolic energy, and its repeatability is only limited by the intensity and duration of rainfall. The underside of the lid is coated with friction-reducing wax crystals, making insects more vulnerable to perturbations. We show that the trapping success of N. gracilis relies on the combination of material stiffness adapted for momentum transfer and the antiadhesive properties of the wax crystal surface. The impact-driven oscillation of the N. gracilis lid represents a new kind of rapid plant movement with adaptive function. Our findings establish the existence of a continuum between active and passive trapping mechanisms in carnivorous plants.
    Print ISSN: 0027-8424
    Electronic ISSN: 1091-6490
    Topics: Biology , Medicine , Natural Sciences in General
    Published by National Academy of Sciences
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