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  • Immunocytochemistry  (97)
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  • 1
    Digitale Medien
    Digitale Medien
    Pitfall-trap catches of the carabid beetle Pterostichus melanarius, in relation to gut contents and prey densities, in insecticide treated and untreated spring barley (1984)
    Springer
    Entomologia experimentalis et applicata 36 (1984), S. 23-30 
    Details
    ISSN: 1570-7458
    Schlagwort(e): Pterostichus melanarius ; Coleoptera ; Carabidae ; pitfall traps ; insecticides ; prey ; hunger ; activity ; Rhopalosiphum padi ; Fenitrothion ; Sumicidin (Fenvalerate) ; spring barley
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Beschreibung / Inhaltsverzeichnis: Résumé Au cours d'essais à grande échelle, effectués en 1981 et 1982, sur orge de printemps, pour évaleur l'effet des insecticides Fenitrothion et Sumicidine (fenvalerate) sur les arthropodes utiles, un accroissement significatif des captures, dans des trappes pièges de Barber, de Pterostichus melanarius (Illiger) a été observé plusierus semaines après le traitement dans les lots traités par rapport aux lots témoins. Significativement plus de femelles de P. melanarius ont été capturées dans les parcelles traitées pendant cette période d'accroissement après traitement. Une diminution correspondante dans les populations de proies a été observée à la suite des traitements. Chaque femelle de P. melanarius des parcelles traitées avait une fraction significativement moins importance de son intestin remplie d'aliments solides (arthropodes) que celles des parcelles non traitées. Des auteurs précédents avaient observé des taux de capture plus rapides dans les trappes et ne plus grande mobilité des carabes affamés. La réduction des populations proies par l'application d'insecticides affamerait les carabes dont l'activité serait par suite plus élevée. Comme le taux de captures dans les trappes est dû à la fois à la taille de la population et à son activité, on en déduit que la capture par trappes seule ne peut donner une image exacte de l'effet des insecticides sur les populations de carabes dans les champs.
    Notizen: Abstract During large-scale field experiments in 1981 and 1982, designed to assess the effects of the insecticides Fenitrothion and Sumicidin (Fenvalerate) on beneficial arthropods in spring barley, significant increases in pitfall-trap catches of Pterostichus melanarius (Illiger) were observed in treated plots compared to untreated controls, several weeks after treatment. Significantly more female P. melanarius were caught in treated plots during these post-treatment increases. Corresponding decreases were observed in prey populations following treatments. Individual female P. melanarius from treated plots had significantly fewer of their gut areas full of solid (arthropod) food when compared to those from untreated control plots. Earlier workers observed both faster recapture rates in pitfalls and higher mobility in hungry carabid beetles. The following hypothesis is suggested: reducing prey populations by the application of insecticides results in hungrier carabid beetles with consequently higher activity. Since pitfall-trap catch is determined not only by population size but also activity, it is argued that pitfall-trap catches alone cannot give a true measure of the effects of insecticides on carabid populations in the field.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00345200
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  • 2
    Digitale Medien
    Digitale Medien
    Ecdysteroids during pupal development of female Xyleborus ferrugineus (1981)
    Springer
    Entomologia experimentalis et applicata 30 (1981), S. 151-156 
    Details
    ISSN: 1570-7458
    Schlagwort(e): Xyleborus ferrugineus ; pupae ; ecdysteroids ; pharate adult ; radioimmunoassay ; Coleoptera ; Scolytidae
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung Der Ecdysteroidtiter weiblicher Puppen von Xyleborus ferrugineus (Fabr.) wurde geschätzt, indem ganze Tiere homogenisiert und radioimmunologisch untersucht wurden. Ein ausgeprägtes Maximum an Ecdysteroiden wurde bei 36 Stunden Puppenent-wicklung beobachtet (743 pg/mg Körpergewicht). Der Titer nahm ab auf 299 pg/mg im Pharatstadium und auf 193 pg/mg unmittelbar vor Schlüpfen der Adulten. Qualitative Studien mit HPLC ergaben in frischen Puppen ein Verhältnis von 3:1 Ecdyson zu 20-Hydrooxyecdyson. Pharatstadien enthielten vor allem 20-Hydrooxyecdyson. Das beobachtete einzige Maximum im Titer stimmt überein mit den Resultaten bei andern untersuchten Coleopteren.
    Notizen: Abstract Ecdysteroid titers were estimated on the whole body homogenates of Xyleborus ferrugineus (Fabr.) female pupae during development by radioimmunoassay. A distinct peak of ecdysteroids was observed at 36-hr pupal development (743 pg/mg body wt). Titer declined to 299 pg/mg by the pharate adult stage and to 193 pg/mg body wt just before adult emergence. Qualitative studies by HPLC revealed a ratio of 3:1 ecdysone to 20-hydroxyecdysone in the initial pupal stage. Pharate adults had mainly 20-hydroxyecdysone. The observed single peak in ecdysteroid titer agrees with findings in other studied coleopteran species.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00300880
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  • 3
    Digitale Medien
    Digitale Medien
    Distribution of proteinases and carbohydrases in the midgut of larvae of the sweetpotato weevilCylas formicarius elegantulus and response of proteinases to inhibitors from sweet potato (1984)
    Springer
    Entomologia experimentalis et applicata 36 (1984), S. 97-105 
    Details
    ISSN: 1570-7458
    Schlagwort(e): Coleoptera ; Curculionidae ; Cylas formicarius elegantulus ; sweetpotato weevil ; sweet potato ; digestion ; enzyme distribution ; trypsin-inhibitors ; resistance
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Beschreibung / Inhaltsverzeichnis: Résumé L'activité endoprotéinase était limitée au liquide de la lumière des régions ventriculaires antérieure et postérieure de l'intestin moyen des larves deCylas formicarius elegantulus Summers. Les aminopeptidases ont été trouvées dans le liquide de la lumière (18%), mais étaient principalement associées avec les fractions insolubles des cellules du ventricule postérieur (82%). Suivant le substrat, l'activité carboxypeptidase était à peu près également répartie entre le liquide de la lumière et les fractions insolubles des cellules du ventricule postérieur. L'amylase, enzyme secrétée, a été observée à la fois dans la lumière antérieure et postérieure. Cinq bandes d'activité amylase ont été révélées sur zymogrammes d'amidon après électrophorèse d'intestins moyens entiers. Trois des bandes d'amylase pouvaient provenir de la plante. Il y avait au moins 2 α-glucosidases, une secrétée et une liée aux cellules du ventricule antérieur. L'activite β-glucosidase était liée aux cellules du ventricule antérieur, fandis que l'activité α-galactosidase était limitée au fluide de la lumière. Les activités β-galactosidase et cellulase ont été trouvées à la fois dans le liquide de la lumière et dans la fraction cellulaire insoluble. Ainsi, la digestion initiale des grosses protéines et des polymères de carbohydrates se produit dans le liquide de la lumière dans les régions ventriculaires antérieure et postérieure. Cependant, l'achèvement de la digestion des oligopeptides se produit principalement dans le ventricule postérieur, tandis que la fin de la digestion des oligosaccharides se produit dans le ventricule antérieur. Les concentrations en inhibiteurs de trypsine de 5 cultivars d'I. batatas L. diffèrent de 1 à 20. Les endoprotéinases deC. formicarius elegantulus ont été inhibées par des extraits de cultivars, mais les cultivars avec des concentrations relativement élevées d'inhibiteur avainent antérieurement montré être susceptibles d'être attaqués par le coléoptère dans des essais en champs.
    Notizen: Abstract Endoproteinase activity was confined to luminal fluid from anterior and posterior ventricular regions of midguts of larvae of the sweetpotato weevil,Cylas formicarius elegantulus (Summers). Aminopeptidase was found in luminal fluid (18%) but was primarily associated with insoluble fractions from cells of the posterior ventriculus (82%). Depending on substrate, carboxypeptidase activity was about equally distributed between luminal fluid and insoluble fractions from posterior ventriculus cells. Amylase was found in luminal fluid in both the anterior and posterior ventriculus. Five bands of amylase activity were detected on starch zymograms following electrophoresis of whole midgut samples. Three of the amylase bands may be plant-derived. At least two α-glucosidases were present, one secreted and one bound to anterior ventriculus cells. β-Glucosidase activity was bound to anterior ventriculus cells whereas α-galactosidase activity was confined to luminal fluid. β-Galactosidase and cellulase activities were found in both luminal fluid and the insoluble cell fraction. Thus, initial digestion of large protein and carbohydrate polymers occurs in luminal fluid in both anterior and posterior ventriculus regions. However, terminal digestion of oligopeptides occurs primarily in the posterior ventriculus while terminal digestion of oligosaccharides occurs in the anterior ventriculus. A 20-fold difference in trypsin-inhibitor concentration was found among five sweetpotato cultivars. Endoproteinases from sweetpotato weevil larvae were inhibited by extracts from the cultivars but cultivars with relatively high concentrations of inhibitor were previously shown to be susceptible to weevil attack in field trials.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00569949
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  • 4
    Digitale Medien
    Digitale Medien
    Characteristics of the S/N ratio of the beat note obtained from the frequency-mixing experiments between a CO2 and an H2O laser (1984)
    Springer
    Applied physics 34 (1984), S. 49-53 
    Details
    ISSN: 1432-0649
    Schlagwort(e): 62.65 ; 42.80
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract The S/N ratio of the beat note obtained from the frequency mixing between a 32 THz CO2 laser, a 10.7 THz H2O laser and a 22 GHz klystron is measured as a function of incident power of both lasers and the klystron on the W-Ni point contact diode. A maximum S/N ratio of 36 dB is obtained. It is found that the S/N ratio arises from the product of the contributions due to the incident power and the fifth coefficient of the current-voltage characteristic of the W-Ni diode. These characteristics are discussed qualitatively.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00697947
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  • 5
    Digitale Medien
    Digitale Medien
    Ninth-order nonlinear polarization and vuv generation in Hg vapor (1984)
    Springer
    Applied physics 34 (1984), S. 171-173 
    Details
    ISSN: 1432-0649
    Schlagwort(e): 42.65 ; 42.80
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract Interference of resonant ninth-order and nonresonant seventh-order nonlinear polarizations in Hg atoms has been studied, and direct conversion of fundamental ir radiation into the vuv has been obtained. The interference has been observed in the form of a Fano-Boitler contour. The efficiency of generation by ninth-order processes appears to be higher than that by seventh-order.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00697511
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  • 6
    Digitale Medien
    Digitale Medien
    Optical-gyroscope application of efficient crossed-channel acoustooptic devices (1984)
    Springer
    Applied physics 35 (1984), S. 113-118 
    Details
    ISSN: 1432-0649
    Schlagwort(e): 42.80
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract An acoustooptic (AO) deflector/modulator using a single-mode crossed-channel waveguide of 2Δn type and an interdigital transducer is fabricated in aY-Z LiNbO3 substrate. This module has shown a high diffraction efficiency. A 50% diffraction efficiency and a bandwidth of 13.4 MHz were obtained with 0.13 W of surface-acoustic wave power centered at 320MHz. Since the cross section of the channel waveguide and that of the optical fiber are comparable, the interfacting of the resultant acoustooptic devices with fiber optical systems would greatly simplified. In addition, the frequency-shifted optical beam can be conveniently used as a reference signal or local oscillator in heterodyne detection. Consequently, this cross-channel acoustooptic device should find a variety of applications in realizing an integrated-optics module with a 50–50% power slit, optical communication, and an optical fiber system. One of those applications, optical gyroscopes, is proposed by using this kind of crossed-channel AO device.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00697430
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  • 7
    Digitale Medien
    Digitale Medien
    Novel spectroscopy (1982)
    Springer
    Applied physics 28 (1982), S. 297-305 
    Details
    ISSN: 1432-0649
    Schlagwort(e): 32 ; 42.80 ; 33 ; 82 ; 34
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00697859
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  • 8
    Digitale Medien
    Digitale Medien
    Origin of laser-output noise of cataphoretic HeSe+ lasers (1982)
    Springer
    Applied physics 28 (1982), S. 373-381 
    Details
    ISSN: 1432-0649
    Schlagwort(e): 42.55 ; 42.80 ; 52
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract We investigated noise and fluctuations of the output power of cataphoretic HeSe+ lasers in positive column plasma. Direct coupling of laser output power noise and fluctuations of the local population inversion was found. An investigation of the positive column plasma showed moving striations being responsible for the gain fluctuations. Whereas the local plasma properties are dominated by high frequency striations in the 100 kHz range, integrated quantities such as laser gain per pass are most strongly influenced by low-frequency waves with a continuous noise spectrum below 200 kHz. External modulation of the discharge voltage or current at a frequency near thehf striations reduces laser noise and increases laser output power.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00686369
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  • 9
    Digitale Medien
    Digitale Medien
    Bragg diffraction of gaussian beams by thick gratings: Numerical evaluations by plane-wave decomposition (1982)
    Springer
    Applied physics 28 (1982), S. 383-390 
    Details
    ISSN: 1432-0649
    Schlagwort(e): 42.10 ; 42.80
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract The validity of 2-D coupled-wave theory is investigated for the case of Bragg diffraction of a Gaussian beam by a thick unslanted phase grating in transmission mode. Fourier plane wave decomposition theory, as presented in a companion article, is used to test 2-D coupled-wave theory under circumstances when its validity is in question, namely when the incident distribution is very narrow or fast-varying, or when the parameterv o, due to Kogelnik (1969), which is proportional to the product of coupling rate and grating thickness, is very large. Numerical evaluations of the field patterns at output from the grating, obtained using plane-wave decomposition, are used to explore the effect of the gradual violation of the conditions (from the previous article) under which 2-D coupled-wave theory is valid.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00686370
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  • 10
    Digitale Medien
    Digitale Medien
    Temporal analysis of a mode-locked Nd-glass laser by four-wave mixing (1982)
    Springer
    Applied physics 29 (1982), S. 263-267 
    Details
    ISSN: 1432-0649
    Schlagwort(e): 42.55 ; 42.65 ; 42.80
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract The duration, shape, and background intensity level of pulses of a passively modelocked Nd-glass laser are determined by noncollinear phase-matched four-photon frequency mixing of time-separated fundamental and second-harmonic pulses in a KI crystal. The pulse shape is found to be slightly asymmetric with slower trailing than rising parts. The background intensity level before and behind the main pulse is about 5¢10−6 the peak pulse intensity.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00689185
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  • 11
    Digitale Medien
    Digitale Medien
    A laser optical method for the determination of tropospheric OH concentrations (1984)
    Springer
    Applied physics 33 (1984), S. 103-113 
    Details
    ISSN: 1432-0649
    Schlagwort(e): 42.68 ; 42.80 ; 42.60
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract A long-path absorption procedure for the determination of tropospheric OH concentrations is described in detail. Initial measurements using this method were carried out in Frankfurt a. M. By including in the evaluation the visible radiation of a frequencydoubled dye laser used in the measurements, it was possible to mathematically reduce the signal fluctuations caused by the scattering and density fluctuations of tropospheric air. The resulting detection limit was 3×106 OH per cm3. SO2 concentrations which had to be simultaneously determined in order to eliminate an interference effect, could be detected in the range of 1–40 ppb on the absorption path.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00688355
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  • 12
    Digitale Medien
    Digitale Medien
    Thick-grating non-divergent focussing device: 2-D analysis (1981)
    Springer
    Applied physics 26 (1981), S. 89-98 
    Details
    ISSN: 1432-0649
    Schlagwort(e): 42.80 ; 42.82 ; 42.10
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract The two-dimensional analysis of a recently reported thick grating Bragg diffraction focussing device is carried out using Solymar's coupled-wave approach. It is shown that the device is capable of operating as a non-divergent lens with beam contraction ratios of better than 100:1, and conversion efficiencies of nearly 100%. It is also shown that it can operate as a novel kind of Fourier spectrum analyser, the focussed diffracted intensity being proportional (as a function of Bragg condition violation) to the modulus squared of the Fourier transform of the incident finite beam. The focussing properties are studied as functions of incident beam profile, width and position, grating strength and Bragg condition violation. Poynting vector optics is used successfully to predict (in conjunction with the dispersion surfaces of x-ray dynamical theory) the off-Bragg behaviour in the focal plane. It is likely that the device could be used as avariable ratio beam contractor in integrated optics, where the grating strength could be controlled (interdigital electrode system) electrooptically.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01284908
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  • 13
    Digitale Medien
    Digitale Medien
    Guided waves and IR lasers (1982)
    Springer
    Applied physics 28 (1982), S. 283-289 
    Details
    ISSN: 1432-0649
    Schlagwort(e): 85.60 ; 42.80 ; 42.55 ; 33
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00697857
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  • 14
    Digitale Medien
    Digitale Medien
    Light-polarization modifications in a multipass cavity (1982)
    Springer
    Applied physics 29 (1982), S. 43-54 
    Details
    ISSN: 1432-0649
    Schlagwort(e): 42.80 ; 32
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract This paper analyses the slight change undergone by the polarization of a laser beam performing a multipass between two spherical mirrors facing each other. We replace the general 16-parameter Mueller formalism by an approximate 7-parameter one, and we give a quantitative experimental criterion for the validity of this approximation. Then we apply this formalism to the analysis of our experimental data. The results evidence:i) intrinsic birefringence in the mirror coatings (typical value per reflexion ∼2 to 4×10−4 rad);ii) birefringence due to off-normal incidence (typically 3.6×10−5 rad per reflexion for an incidence of 2×10−2 rad);iii) optical rotation, of purely geometrical origin (typically 14° for a multipass with revolution symmetry and 100 forward-backward passes under constant incidencei=2°);iv) no observable circular dichroism (≲10−6). Finally these results are discussed in connection with possible associated systematics in a parity violation experiment which motivated this work.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00694368
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  • 15
    Digitale Medien
    Digitale Medien
    Coherent transient phenomena (1982)
    Springer
    Applied physics 29 (1982), S. 179-182 
    Details
    ISSN: 1432-0649
    Schlagwort(e): 33 ; 34 ; 36 ; 42.80
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00688662
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  • 16
    Digitale Medien
    Digitale Medien
    Simultaneous phase-lock of five CO2 lasers to a primary Cs frequency standard (1984)
    Springer
    Applied physics 35 (1984), S. 119-122 
    Details
    ISSN: 1432-0649
    Schlagwort(e): 42.72 ; 42.80 ; 42.60
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract The output of a CO2 laser, operating on theP I(18) transition of13C16O2 at 26941 GHz (11.128 μm) was phase-locked to a 5 MHz signal from a primary Cs frequency standard by means of a frequency chain having only CO2 lasers as infrared sources. Simultaneously, four other CO2 lasers in the chain were phase-locked to the 26941 GHz output. This provided CO2 laser frequencies at 26 450 305, 26 940 815, 28 694 625, 29 442 480, and 33 185 715 MHz having zero long-term-average frequency error relative to the Cs standard, and the ±10−13 (≃3 Hz) long-term absolute uncertainty of the standard.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00697698
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  • 17
    Digitale Medien
    Digitale Medien
    Ellipsometry on magnetooptic thin film multilayer systems (1984)
    Springer
    Applied physics 34 (1984), S. 139-143 
    Details
    ISSN: 1432-0649
    Schlagwort(e): 42.80 ; 78.20L
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract The optical and magnetooptical properties of thin film multilayer systems including a ferromagnetic absorbing layer were measured by ellipsometry. These were compared to calculations, using the ellipsometric data of each individual layer and measuring their thicknesses by FECO to determine the refractive indices and magnetooptical parameters of each layer for the calculation of the whole stack. Agreement between calculated and measured properties of the stack showed to be strongly dependent on the precision in measuring film thickness.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00697506
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  • 18
    Digitale Medien
    Digitale Medien
    Sub-Doppler excited molecule energy transfer spectroscopy (1982)
    Springer
    Applied physics 27 (1982), S. 153-156 
    Details
    ISSN: 1432-0649
    Schlagwort(e): 33 ; 42.80 ; 07.65
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract A sub-Doppler spectroscopic technique involving the detection of vibrational energy transfer in excited molecules with selected velocity components at a microphone diaphragm is demonstrated. The technique is applied to the investigation of thev 3 R(16) transition in HCN and the results compared with a previously derived theoretical model.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00694641
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  • 19
    Digitale Medien
    Digitale Medien
    F-center-laser. Superconductivity (1982)
    Springer
    Applied physics 28 (1982), S. 306-310 
    Details
    ISSN: 1432-0649
    Schlagwort(e): 68 ; 42.70 ; 42.60 ; 61.70 ; 61.50 ; 42.80 ; 29
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00697860
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  • 20
    Digitale Medien
    Digitale Medien
    Formation of blazed holographic gratings (1982)
    Springer
    Applied physics 28 (1982), S. 349-353 
    Details
    ISSN: 1432-0649
    Schlagwort(e): 42.80 ; 42.82
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract Various methods for the recording of blazed holographic diffraction gratings are presented and the regions in the wavelength-groove density plane for which they can be used are shown. The gratings are made in the positive photoresist Shipley AZ-1350. The diffraction efficiency for s and p polarization was measured as a function of wavelength and angle of incidence. An absolute efficiency of 80% was achieved.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00686365
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  • 21
    Digitale Medien
    Digitale Medien
    Conditions for the harmonic-like and efficient amplitude modulation of the cw gaussian laser beam by means of a mechanical chopper (1984)
    Springer
    Applied physics 34 (1984), S. 1-4 
    Details
    ISSN: 1432-0649
    Schlagwort(e): 42.80 ; 42.60
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract The values of the chopping disc slot and mark space widths relative to the radius of the Gaussian beam are found, which achieve optimum harmonic-like and efficient amplitude modulation of the cw laser beam. The simple approximation for the waveform of the modulated laser power valid for these optimum or near optimum values of the chopping disc parameters is presented.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00697456
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  • 22
    Digitale Medien
    Digitale Medien
    Apparent transfer function for partially coherent optical information processing (1982)
    Springer
    Applied physics 28 (1982), S. 359-366 
    Details
    ISSN: 1432-0649
    Schlagwort(e): 42.30 ; 42.80
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract In this paper, the general formulations of the apparent transfer function for the partially coherent optical processor will be derived. Although these formulas show that the apparent transfer function is dependent upon the degree of spatial and temporal coherence, there is actually more variability in the spatial coherence. We note that the obtained formulas may also be used as a criterion in the selection of source size and spectral bandwidth of an incoherent light source. Thus a specific optical information processing operation can be carried out with an incoherent source.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00686367
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  • 23
    Digitale Medien
    Digitale Medien
    Development of an optical time scale (1982)
    Springer
    Applied physics 29 (1982), S. 63-65 
    Details
    ISSN: 1432-0649
    Schlagwort(e): 42.60 ; 42.80
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract A time standard based on the use of an optical oscillation period of a frequencystable He−Ne laser as a time scale is first described. We obtained highly frequency-stable oscillations in the SHF range that were locked to the oscillations of a He−Ne laser stabilized to an absorption resonance in methane at 3.39 μm. A direct comparison of frequency stabilities of a rubidium standard and He−Ne/CH4 laser has been made. The absolute measurement of the frequency of the He−Ne/CH4 laser we performed gave a new value of frequency.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00694370
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  • 24
    Digitale Medien
    Digitale Medien
    Energy transfer processes in two different bifluorophoric laser dyes (1982)
    Springer
    Applied physics 29 (1982), S. 73-77 
    Details
    ISSN: 1432-0649
    Schlagwort(e): 82 ; 78.60 ; 42.80
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract The mechanism of intramolecular energy transfer in two bifluorophoric laser dyes has been investigated by measurements of laser parameters, excited state absorption and phosphorescence spectra. The new value found for the dimethyl-POPOP triplet energy (48.0 kcal/mole) accounts for the different behaviour of the two classes of bifluorophoric dyes used in this investigation.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00692766
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  • 25
    Digitale Medien
    Digitale Medien
    Novel quantum-electronics phenomena and devices (1982)
    Springer
    Applied physics 29 (1982), S. 152-156 
    Details
    ISSN: 1432-0649
    Schlagwort(e): 42.80 ; 42.55
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00688656
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  • 26
    Digitale Medien
    Digitale Medien
    Dynamical nonlinear optics and bistability (1982)
    Springer
    Applied physics 29 (1982), S. 169-175 
    Details
    ISSN: 1432-0649
    Schlagwort(e): 42.80 ; 42.65
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00688660
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  • 27
    Digitale Medien
    Digitale Medien
    Ethylene monitoring by differential absorption with a CO2 waveguide laser (1982)
    Springer
    Applied physics 29 (1982), S. 227-233 
    Details
    ISSN: 1432-0649
    Schlagwort(e): 86 ; 70L ; 07.60 ; 42.80
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract In this paper we report on a differential absorption technique using a CO2 waveguide laser. The method is based on the measurement of the differential absorption between two different frequencies of the same selected CO2 laser line. The sensitivity of the technique depends strongly on the total pressure and has been estimated to be about a few tens of ppb or better over a 1 km path length in C2H4 diluted with air to a total pressure of a few tens of torrs. Its relative simplicity and high sensitivity at low total pressure enable this technique to be applied to gas detection either at high altitude or to local monitoring of a low pressure sample.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00688673
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  • 28
    Digitale Medien
    Digitale Medien
    Harmonic detection with tunable diode lasers —two-tone modulation (1982)
    Springer
    Applied physics 29 (1982), S. 279-285 
    Details
    ISSN: 1432-0649
    Schlagwort(e): 07.65 ; 42.80
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract The minimum absorption detectable by a tunable diode laser spectrometer utilising harmonic techniques is often limited by interference fringes generated by scattered light. The sensitivity of the spectrometer to absorption can be increased by applying a jitter modulation. In this paper, the theory of harmonic response for single- and two-tone modulation over optical fringes and Lorentzian absorption lines is developed and compared to experimental measurements. A simple analytic expression for the two-tone harmonic line shape is derived. This expression provides a physical understanding of the effects of the second modulation, and a means to unravel the effects of the second modulation on the linewidth and line shape. For a specific choice of the jitter frequency and phase, it is possible to simultaneously minimise the fringe signal and increase the harmonic absorption signal. The results of this investigation are applicable to trace gas detection using tunable diode lasers, and to other areas of spectroscopy and magnetic resonance where harmonic techniques are used.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00689188
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  • 29
    Digitale Medien
    Digitale Medien
    Effects of a lossy thin plasma-film on metal-diffused LiNbO3 optical waveguides (1984)
    Springer
    Applied physics 35 (1984), S. 23-30 
    Details
    ISSN: 1432-0649
    Schlagwort(e): 42.80 ; 41
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract I intend to investigate the effects of different kinds of partially reflecting metal film (plasma layer) on the wave characteristics of a stratified titanium-diffused LiNbO3 optical waveguide. The mode number, the equivalent indices, the extinction coefficients, the field distributions and the powers carried in each layer are given as a function of the free-space wavelength, of the diffusion parameters, and of the opticc-axis orientation. Of course, the power of TM-like hybrid waves flows in opposite directions in the plasma and the other regions. For ac-axis varying in the transverse plane, the ith-order hybrid mode is rather complicated in the guide with an aluminum layer. There, in fact, the field mapping can be seen as an overlap of a TE i with a TM i+1, mode because of a sudden transformation of the TM0 mode into a superficial plasma wave (SPW). On the contrary, with a silver layer, the hybrid field is a simple combination of a TE i with a TM i mode with no SPW growing. The guide losses assume the lowest values (1 dB/cm) for an Ag layer which is the prime candidate for making electro-optical or acoustic-optical devices. On the other hand, the nickel film causes the highest losses (≧66 dB/cm).
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00697517
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  • 30
    Digitale Medien
    Digitale Medien
    A diffraction grating autocorrelator for measurement of single ultrashort light pulses (1984)
    Springer
    Applied physics 35 (1984), S. 45-48 
    Details
    ISSN: 1432-0649
    Schlagwort(e): 42.80 ; 06.60Jn
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract A simple autocorrelation scheme for measurement of single ultrashort light pulses in the 1–500 ps range is proposed. Only a diffraction grating and a mirror are utilized to obtain a variable time delay between two collinear beams. The advantages of the proposed method and the effect of the grating dispersion on the autocorrelator performance are discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00697520
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  • 31
    Digitale Medien
    Digitale Medien
    Low threshold optical bistability with optical pumping (1982)
    Springer
    Applied physics 29 (1982), S. 79-87 
    Details
    ISSN: 1432-0649
    Schlagwort(e): 42.50 ; 42.65 ; 42.80
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract By use of circularly polarized light we have exploited optical pumping within the Zeeman sublevels of the ground state to obtain optical bistability in sodium vapours with low threshold power (around 1 mW) and a wide tuning range (〉12 GHz). Experimental results are presented for different conditions of operation and compared to computer calculations, that include propagation effects and inhomogeneous broadening, based on a three-level atomic model that accounts for optical pumping.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00692767
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  • 32
    Digitale Medien
    Digitale Medien
    The analysis of excite and probe measurements of relaxation times with fluctuating pulse duration (1982)
    Springer
    Applied physics 29 (1982), S. 135-138 
    Details
    ISSN: 1432-0649
    Schlagwort(e): 06 ; 42.80
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract The effect of fluctuations in the pulse duration of synchronously pumped modelocked pulse trains on excite and probe measurements is discussed. Relaxation times comparable with the pulse durations can be measured even when large pulse-to-pulse fluctuations in duration exist. The pump and probe pulse durations are assumed to be correlated. When the probe pulses are the second harmonic of the pump, or vice versa, the third harmonic must also be generated to permit deconvolution of experimental excite and probe data. When the pump and probe pulses have the same time dependence, the excite and probe curves consist of the desired response function convolved with the time-averaged second harmonic autocorrelation function which is easily measured. Deconvolution yields the relaxation time but fluctuations in pulse duration increase the root-mean-square voltage fluctuation at the output of the detector system and limit the accuracy with which the relaxation time can be calculated.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00692776
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  • 33
    Digitale Medien
    Digitale Medien
    Surface spectroscopy (1982)
    Springer
    Applied physics 29 (1982), S. 182-185 
    Details
    ISSN: 1432-0649
    Schlagwort(e): 36 ; 42.80 ; 52
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00688663
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  • 34
    Digitale Medien
    Digitale Medien
    Anisotropic selfdiffraction in BaTiO3 (1984)
    Springer
    Applied physics 35 (1984), S. 17-21 
    Details
    ISSN: 1432-0649
    Schlagwort(e): 42.70 ; 42.65 ; 42.80
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract Anisotropic selfdiffraction in BaTiO3 crystals utilizing the large electrooptic coefficientr 42 is described. In the absence of an external electric field the generated space charge field is determined by diffusion processes. The theory is in agreement with the experimental results. The angles between extraordinary and ordinary beams, the intensity and time dependence of transmitted and diffracted beams, and phase conjugation effects are measured and evaluated.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00697516
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  • 35
    Digitale Medien
    Digitale Medien
    Influence of fluctuating pulse durations on the time resolution of probing experiments (1981)
    Springer
    Applied physics 26 (1981), S. 213-216 
    Details
    ISSN: 1432-0649
    Schlagwort(e): 06 ; 42.80
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract Fluctuating pulse durations considerably influence the time resolution of probing experiments. The commonly used arithmetic averaging the experimental data changes the shape of the signal curves and gives longer decay times in the wings. Methods are presented to reduce the effect of fluctuating pulse durations.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00692540
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  • 36
    Digitale Medien
    Digitale Medien
    Three-dimensional surface measurement using the confocal scanning microscope (1982)
    Springer
    Applied physics 27 (1982), S. 211-213 
    Details
    ISSN: 1432-0649
    Schlagwort(e): 06 ; 42.80
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract The use of the depth discriminination property of the confocal scanning microscope for surface profiling has been adapted to provide a method of high-resolution three-dimensional surface profilometry. Measurements on a semiconductor specimen demonstrate the technique; depth variations of the order of 0.1 μm are clearly resolved.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00697444
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  • 37
    Digitale Medien
    Digitale Medien
    On the relation between genetic and environmental variability in animals (1982)
    Springer
    Journal of molecular evolution 18 (1982), S. 310-314 
    Details
    ISSN: 1432-1432
    Schlagwort(e): Neutral mutation theory ; Natural selection ; Protein evolution ; Levene model ; Environmental variability ; Genetic variability ; Drosophila
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary If a phenotypic character is under stabilizing selection, the selective disadvantage of a nonoptimal genotype will decrease exponentially to zero as the proportion of phenotypic variation that is environmental in origin -V e /V p - increases. Under the modified mutation-drift hypothesis of genetic polymorphism, the proportion of mutations that are effectively neutral and average heterozygosity should increase with this ratio. Invertebrates, because of their small size, fast development, and low degree of homeostasis (relative to vertebrates), are expected to show a larger environmental component of phenotypic variation than vertebrates. This may help explain why invertebrates are in general more genetically variable than vertebrates and why, when laboratory populations ofDrosophila are maintained in heterogeneous environments, genetic variability is lost less rapidly than when they are kept in constant conditions.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01733897
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  • 38
    Digitale Medien
    Digitale Medien
    Adjacent chromosomal regions can evolve at very different rates: Evolution of theDrosophila 68C glue gene cluster (1984)
    Springer
    Journal of molecular evolution 20 (1984), S. 251-264 
    Details
    ISSN: 1432-1432
    Schlagwort(e): Drosophila ; Genome evolution ; 68C Glue gene cluster ; Drosophila melanogaster species subgroup
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The 68C puff is a highly transcribed region of theDrosophila melanogaster salivary gland polytene chromosomes. Three different classes of messenger RNA originate in a 5000-bp region in the puff; each class is translated to one of the salivary gland glue proteins sgs-3, sgs-7, or sgs-8. These messenger RNA classes are coordinately controlled, with each RNA appearing in the third larval instar and disappearing at the time of puparium formation. Their disappearance is initiated by the action of the steroid hormone ecdysterone. In the work reported here, we studied evolution of this hormone-regulated gene cluster in themelanogaster species subgroup ofDrosophila. Genome blot hybridization experiments showed that five other species of this subgroup have DNA sequences that hybridize toD. melanogaster 68C sequences, and that these sequences are divided into a highly conserved region, which does not contain the glue genes, and an extraordinarily diverged region, which does. Molecular cloning of this DNA fromD. simulans, D. erecta, D. yakuba, andD. teissieri confirmed the division of the region into a slowly and a rapidly evolving protion, and also showed that the rapidly evolving region of each species codes for third instar larval salivary gland RNAs homologous to theD. melanogaster glue mRNAs. The highly conserved region is at least 13,000 bp long, and is not known to code for any RNAs.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02104731
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  • 39
    Digitale Medien
    Digitale Medien
    Second-harmonic detection with tunable diode lasers — Comparison of experiment and theory (1981)
    Springer
    Applied physics 26 (1981), S. 203-210 
    Details
    ISSN: 1432-0649
    Schlagwort(e): 07.65 ; 42.80
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract A series of experiments are carried out by current modulating a tunable diode laser, and slowly ramping the wavelength to scan weak absorption lines in gases at pressures ranging from 2 to 60 Torr. A lock-in amplifier detects the second harmonic (2f) of the modulation frequency, and the experimental 2f signals are compared with theory. Detailed measurements are made on Lorentzian, Voigt, and Gaussian line profiles, over a wide range of modulation amplitudes. Excellent agreement between experiment and calculation is obtained in all cases. This quantitative understanding enables one to derive true lineshapes and linewidths of very weak absorption lines from measurements of 2f lineshapes only. Results are applicable to trace gas detection using tunable diode lasers, and to other areas of spectroscopy and magnetic resonance where harmonic detection techniques are routinely employed to monitor weak signals.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00692448
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  • 40
    Digitale Medien
    Digitale Medien
    Source encoding for partially coherent optical processing (1982)
    Springer
    Applied physics 27 (1982), S. 99-104 
    Details
    ISSN: 1432-0649
    Schlagwort(e): 42.30 ; 42.80
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract A relation between spatial coherence function and source encoding intensity transmittance function is presented. Since the spatial coherence is depending upon the information processing operation, a strictly broad spatial coherence function may not be required for the processing. The advantage of the source encoding is to relax the constraints of strict coherence requirement, so that the processing operation can be carried out with an extended incoherent source. Emphasis of the source encodings and experimental demonstrations are given. The constraint of temperal coherence requirement is also discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00697556
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  • 41
    Digitale Medien
    Digitale Medien
    Bragg diffraction of finite beams by thick gratings: Two rival theories (1982)
    Springer
    Applied physics 28 (1982), S. 63-72 
    Details
    ISSN: 1432-0649
    Schlagwort(e): 42.10 ; 42.80
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract Two rival techniques used in the analysis of Bragg diffraction of two-dimensional light beams by thick unslanted phase gratings, namely Fourier plane wave decomposition and 2-D coupled-wave theory, are compared. The advantages and regions of applicability of each are discussed, and the conditions found under which they yield identical results. In particular, the results of plane-wave decomposition are used to provide quantitative conditions for validity of 2-D coupled-wave theory. These conditions are not easily derived using any other technique, and set quantitative limits to how narrow or fast-varying the incident distribution may be before 2-D coupled-wave theory fails. It is also shown that 2-D coupled-wave theory is inadequate when the parameterv 0, due to Kogelnik (1969), which is proportional to the product of coupling rate and grating thickness, is very large.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00693894
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  • 42
    Digitale Medien
    Digitale Medien
    Applications of ps-pulses (1982)
    Springer
    Applied physics 28 (1982), S. 246-254 
    Details
    ISSN: 1432-0649
    Schlagwort(e): 42.80 ; 42.65 ; 34 ; 42.55 ; 42.70 ; 78
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00697852
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  • 43
    Digitale Medien
    Digitale Medien
    Theory II (1982)
    Springer
    Applied physics 28 (1982), S. 255-261 
    Details
    ISSN: 1432-0649
    Schlagwort(e): 42.55 ; 36.20 ; 36.10 ; 02 ; 36 ; 42.80
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00697853
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  • 44
    Digitale Medien
    Digitale Medien
    Coherent transient phenomena (1982)
    Springer
    Applied physics 28 (1982), S. 274-282 
    Details
    ISSN: 1432-0649
    Schlagwort(e): 42.80 ; 33 ; 36 ; 36.10 ; 14 ; 32
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00697856
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  • 45
    Digitale Medien
    Digitale Medien
    Thick grating focussing-device-design using poynting-vector-optics (1981)
    Springer
    Applied physics 26 (1981), S. 37-42 
    Details
    ISSN: 1432-0649
    Schlagwort(e): 42.80 ; 42.82 ; 42.10
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract Novel thick grating focussing and de-focussing devices are described which employ uniform phase gratings with special boundary shapes. The analysis used is based upon an eigenmodal approach to Kogelnik's coupled-wave equations, akin to the dynamical theory of x-ray diffraction. The relationship between the direction of phase progression of the coupled-waves at Bragg incidence, and the direction of the Poynting vector is carefully delineated. As a consequence, a new technique-Poynting Vector Optics — is suggested as potentially an important means of designing thick gratings to fulfil certain beam processing roles, especially in integrated optics applications. The two-dimensional coupled-wave equations are briefly employed to illustrate the effectiveness of a particular focussing device.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00702685
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  • 46
    Digitale Medien
    Digitale Medien
    A novel method of DNA transfection by laser microbeam cell surgery (1984)
    Springer
    Applied physics 35 (1984), S. 135-140 
    Details
    ISSN: 1432-0649
    Schlagwort(e): 07.60 ; 42.80 ; 87
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract A new technique is presented to incorporate exogeneous gene materials (DNA) into cells with a microbeam irradiation from an uv pulsed laser. A frequency-multiplied Nd:YAG laser, 355 m wavelength, 5 ns pulse duration, punches a self-healing hole of submicrometer aperture in cell membrane under selected irradiation conditions. It takes a fraction of a second for the aperture to close, long enough to allow the foreign DNA, contained in the medium, to slip into the cell. The method offers a clear advantage over existing methods: increases the success rate of DNA transfection as well as the efficiency of cell modification by orders of magnitude.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00697702
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  • 47
    Digitale Medien
    Digitale Medien
    Faraday rotation in a single-mode fiber with controlled birefringence (1984)
    Springer
    Applied physics 35 (1984), S. 145-148 
    Details
    ISSN: 1432-0649
    Schlagwort(e): 42.80 ; 42.10
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract Faraday rotation within a polarization non-conserving single-mode optical fiber is used for ac magnetic field measurement. For that purpose the intrinsic fiber birefringence on the path to and from the Faraday rotation section is controlled. As control devices externally applied stress birefringence and phase retarder plates were used. With respect to magnetic field measurements on high electric potentials all control devices are placed at fiber input and output only.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00697704
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  • 48
    Digitale Medien
    Digitale Medien
    New lasers II (1982)
    Springer
    Applied physics 28 (1982), S. 233-239 
    Details
    ISSN: 1432-0649
    Schlagwort(e): 42.70 ; 42.55 ; 42.80
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00697850
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  • 49
    Digitale Medien
    Digitale Medien
    Laser fusion (1982)
    Springer
    Applied physics 28 (1982), S. 269-273 
    Details
    ISSN: 1432-0649
    Schlagwort(e): 52 ; 42.55 ; 42.80 ; 51
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00697855
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  • 50
    Digitale Medien
    Digitale Medien
    Fundamental absorption edge of evaporated amorphous WO3 films (1981)
    Springer
    Applied physics 24 (1981), S. 55-59 
    Details
    ISSN: 1432-0630
    Schlagwort(e): 78.20 ; 42.80 ; 85.60
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau , Physik
    Notizen: Abstract The fundamental absorption edge of evaporated WO3 films is investigated. The optical gap of the virgin film is estimated to be 3.41 eV at room temperature and it decreases with increase of annealing temperature up to 200°C. Annealing at 300°C leads to change in the spectral shape, which is caused by crystallization. For the films annealed at 200°C, temperature coefficient of the optical gap is estimated to be −2×10−4 eV/K and the slope of Urbach's tail is found to be independent of measuring temperature up to 200°C. With electrolytic coloration, shift of the optical gap toward higher energy is observed. Magnitude of this shift is estimated to be 0.05 eV at the color center concentration of 7.5×1021 cm−3 when H+ electrolyte is used. If Li+ electrolyte is used, the magnitude of this shift is about three times larger than in the case of H+ electrolyte. This fact is interpreted by a small change in the host matrix structure owing to the injection of proton or Li+ during coloration.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00900398
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  • 51
    Digitale Medien
    Digitale Medien
    Free-running ruby laser annealing of boron implanted silicon (1981)
    Springer
    Applied physics 26 (1981), S. 243-246 
    Details
    ISSN: 1432-0630
    Schlagwort(e): 61.80 ; 42.80 ; 85.30
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau , Physik
    Notizen: Abstract An analytical treatment of the thermal phenomena during free-running ruby laser annealing of boron implanted silicon is presented. The heat equation was solved for a simplified shape of the pulse train consisting of a uniform succession of triangular spikes, identical in energy. During one spike the optical and thermal parameters of the sample were taken constant, but for each new spike, new values of these parameters were calculated taking into account their temperature dependence. Such a model predicts the melting of the top surface before the laser pulse has ended, for energy densities higher than 9×104 J/m2. RHEED confirms the presence of recristallization at about the same value of the laser-pulse energy densities.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00617845
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  • 52
    Digitale Medien
    Digitale Medien
    Time delays in lead-salt semiconductor diode lasers (1984)
    Springer
    Applied physics 33 (1984), S. 181-182 
    Details
    ISSN: 1432-0630
    Schlagwort(e): 42.80
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau , Physik
    Notizen: Abstract Time delays of typically 15–17μ have been measured directly for PbS1−xSex, Pb1−xSnxSe and Pb1−xSnxTe diode lasers at injection levels just above threshold in each case. The corresponding minority carrier lifetimes, as determined using the one-carrier injection model, were typically 2–4μ.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00618753
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  • 53
    Digitale Medien
    Digitale Medien
    The dielectric constant of PbTe at 4.2 K and $$\tilde v$$ =84.15 cm-1, 96.97cm−1, 103.60cm−1 (1982)
    Springer
    Applied physics 28 (1982), S. 229-233 
    Details
    ISSN: 1432-0630
    Schlagwort(e): 77 ; 42.80
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau , Physik
    Notizen: Abstract The dielectric constant of a PbTe epitaxial layer has been measured by surface wave spectroscopy using an optically pumped far-infrared laser and the technique of attenuated total reflection.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00618699
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  • 54
    Digitale Medien
    Digitale Medien
    Full-automatic broad-band wavelength control of a pulsed dye laser (1981)
    Springer
    Applied physics 24 (1981), S. 331-340 
    Details
    ISSN: 1432-0630
    Schlagwort(e): 06.60 ; 42.60 ; 42.80
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau , Physik
    Notizen: Abstract A full-automatic wavelength controled pulsed dye laser has been developed. With the control system, dye laser oscillations of nanosecond pulses are tuned to any wavelength in the visible or scanned in any sweep mode keeping the nearly transform-limited bandwidth of 0.45 GHz. A mechanical tuning of the wavelength is employed, such that the motion of three wavelength selectors is synchronized to give a smooth and precise wavelength control. The basic principle underlying the tuning scheme, various requirements to be met in system construction, and the practical performance of automatic wavelength control are described in this paper.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00899731
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  • 55
    Digitale Medien
    Digitale Medien
    High precision wavelength meter with Fabry-Perot optics (1981)
    Springer
    Applied physics 25 (1981), S. 311-316 
    Details
    ISSN: 1432-0630
    Schlagwort(e): 07.40 ; 07.60 ; 42.60 ; 42.80
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau , Physik
    Notizen: Abstract A high precision wavelength meter in the visible is described, which is based on a Fabry-Perot interferometer with several etalons of different resolution. The interference fringe pattern projected on a photo-diode array detector is computationally processed to give a stepwise refinement of the wavelength value to any adjusted accuracy. The present model intends to provide digital and real-time values of high precision wavelength for dye-laser spectroscopy, and to serve as a monitor or as a pilot for wavelength control of a dye-laser source of nanosecond pulses. The model is, therefore, designed with particular emphasis on its short-pulse capability and on-line mode of operation as well as on its high sensitivity and resolution. Some arrangements of essential necessity are involved therein, such as to avoid an errorneous wavelength readout for a noisy incidence of pulsed field. The ultimate accuracy of wavelength measurement is prescribed by the resolving power of the thickest etalon employed. As applied to the pulsed source, the model determines the wavelength to the accuracy of ±one part in 107 for even a single shot nanosecond incidence of a fraction of μJ energy. The design and performance are described in connection to pulsed dye-laser incidence.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00902989
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  • 56
    Digitale Medien
    Digitale Medien
    Formation of holographic diffraction gratings in photoresist (1981)
    Springer
    Applied physics 26 (1981), S. 143-149 
    Details
    ISSN: 1432-0630
    Schlagwort(e): 42.80 ; 42.82
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau , Physik
    Notizen: Abstract The exposure-development process for the fabrication of holographic diffraction gratings for integrated optics in the positive photoresist Shipley AZ-1350 is theoretically and experimentally investigated. An analysis of the light intensity distribution is carried out, taking into account the reflectivity at the photoresist-substrate interface and the attenuation in the photoresist for two holographic exposure arrangements. The influence of the exposure energy, the development time for a fixed concentration of the developer and the initial photoresist thickness are described. Various grating profiles are calculated for photoresist films, coated on matched and reflective substrates. Scanning electron micrographs demonstrate very good agreement between the actual and calculated gratings profiles.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00614748
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  • 57
    Digitale Medien
    Digitale Medien
    Photoconducting tellurium for submillimeterwave detectors (1982)
    Springer
    Applied physics 27 (1982), S. 35-38 
    Details
    ISSN: 1432-0630
    Schlagwort(e): 42.80 ; 72.40 ; 78.20
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau , Physik
    Notizen: Abstract Undoped tellurium single crystals show at low temperatures (2.2 K) strong photoeffect under submillimeter irradiation. Therefore, tellurium was used as a FIR-detector. For a comparison with other detectors signal-to-noise ratio, response time, and noise equivalent power were determined. Tests were carried out with HCN-laser radiation (λ = 337 μm,≈ν = 30 cm- t). The sensitivity of the Tc-photoconductor is comparable to that of a TGS-bolometer but lower than that of a Ge-bolometer. The Te-detector is much faster than the bolometers.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01197544
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  • 58
    Digitale Medien
    Digitale Medien
    Laser amplification in an optical fiber by evanescent field coupling (1981)
    Springer
    Applied physics 24 (1981), S. 201-203 
    Details
    ISSN: 1432-0630
    Schlagwort(e): 42.10 ; 42.80 ; 42.50
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau , Physik
    Notizen: Abstract A laser signal propagating in an optical fiber is amplified by the evanescent field interacting with the excited Rhodamine 6 G solution surrounding the fiber. A small signal gain of 430 at 600 nm has been measured in a long fiber with a 2 cm long fiber optic amplifier.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00899756
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  • 59
    Digitale Medien
    Digitale Medien
    Optical method for measuring the coupling constant of surface acoustic waves (1982)
    Springer
    Applied physics 27 (1982), S. 95-97 
    Details
    ISSN: 1432-0630
    Schlagwort(e): 42.80 ; 62
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau , Physik
    Notizen: Abstract The coupling constant of common or thin-layered-piezoelectric interdigital transducers for surface acoustic waves up to the highest frequencies can be determined in an optical way with reproducibility better than 3%. Being a nondestructive and noncontact method one can apply it in the technological process for fabricating uniform piezoelectric layered transducers.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00615811
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  • 60
    Digitale Medien
    Digitale Medien
    Space-time resolved reflectivity measurements of picosecond laser-pulse induced phase transitions in (111) silicon surface layers (1982)
    Springer
    Applied physics 27 (1982), S. 153-160 
    Details
    ISSN: 1432-0630
    Schlagwort(e): 78.20 ; 81 ; 42.80
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau , Physik
    Notizen: Abstract The changes in reflectivity of a silicon surface, irradiated by a green picosecond pulse, are probed during and following that pulse with a spatial resolution of 10 μm. The data indicate the development of a liquid phase, and a resolidification either into a single crystal or an amorphous phase. The latter has a characteristic ring-type pattern, and occurs only at locations where the incident picosecond laser fluence lies between 0.2 and 0.26 J/cm2. The reflectivity data appear to be in good quantitative agreement with a “simple heating” model, in which the electrons and phonons maintain a local thermodynamic equilibrium on a picosecond time scale.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00616666
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  • 61
    Digitale Medien
    Digitale Medien
    Radiation sensitivity of thick core all-glass fibers in reactor radiation fields (1982)
    Springer
    Applied physics 28 (1982), S. 45-51 
    Details
    ISSN: 1432-0630
    Schlagwort(e): 42.10 ; 42.80 ; 78.20
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau , Physik
    Notizen: Abstract Radiation induced losses and the recovery behavior of several optical fibers have been determined by in situ steady state and by pulse measurements in a nuclear reactor. Agreement with the literature was found for Suprasil and Fibropsil core fibers in ionizing radiation, but our results on Suprasil-W core fibers show an appreciably higher radiation hardness of this material than reported elsewhere. Additionally, increased long term losses were observed, when the mixed radiation flux contained a noticeable content of neutrons.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00617781
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  • 62
    Digitale Medien
    Digitale Medien
    Mutations affecting the pattern of the larval cuticle inDrosophila melanogaster (1984)
    Springer
    Development genes and evolution 193 (1984), S. 267-282 
    Details
    ISSN: 1432-041X
    Schlagwort(e): Drosophila ; Larval cuticle ; Pattern formation ; Embryonic lethal mutations
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary In a search for embryonic lethal mutants on the second chromosome ofDrosophila melanogaster, 5764 balanced lines isogenic for an ethyl methane sulfonate (EMS)-treatedcn bw sp chromosome were established. Of these lines, 4217 carried one or more newly induced lethal mutations corresponding to a total of 7600 lethal hits. Eggs were collected from lethal-bearing lines and unhatched embryos from the lines in which 25% or more of the embryos did not hatch (2843 lines) were dechorionated, fixed, cleared and scored under the compound microscope for abnormalities of the larval cuticle. A total of 272 mutants were isolated with phenotypes unequivocally distinguishable from wild-type embryos on the basis of the cuticular pattern. In complementation tests performed between mutants with similar phenotype, 48 loci were identified by more than one allele, the average being 5.4 alleles per locus. Complementation of all other mutants was shown by 13 mutants. Members of the complementation groups were mapped by recombination analysis. No clustering of loci with similar phenotypes was apparent. From the distribution of the allele frequencies and the rate of discovery of new loci, it was estimated that the 61 loci represent the majority of embryonic lethal loci on the second chromosome yielding phenotypes recognizable in the larval cuticle.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00848156
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  • 63
    Digitale Medien
    Digitale Medien
    Isolation and characterization of temperature-sensitivelethal (2) giant larva alleles (1984)
    Springer
    Development genes and evolution 193 (1984), S. 90-97 
    Details
    ISSN: 1432-041X
    Schlagwort(e): Drosophila ; Temperature-sensitive ; Neoplasms ; Differentiation ; Imaginal discs
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary EMS induced temperature-sensitivelethal (2) giant larva, 1(2)gl, alleles were isolated by screening against a knownl(2)gl allele. Analysis of the lethal phase of thel(2)gl ts-deficiency heterozygotes demonstrated: (1) the majority of thel(2)gl tslarvae survive to late third instar, (2) at 29°C the majority of thel(2)gl tslarvae failed to pupate and only rarely did they differentiate adult cuticular structures, (3) at 15°C the majority of the larvae pupated and frequently differentiated adult cuticular structures. Examination of the imaginal discs ofl(2)gl tslarvae reared at 29°C revealed the presence of morphologically abnormal wing, haltere and leg imaginal discs. No morphologically abnormal discs were found in thel(2)gl tslarvae reared at 15°C. Studies on both the histology and the developmental capacity of the morphologically normal and abnormall(2)gl tsdiscs were performed. The morphologically normal discs are histologically normal and produce a full complement of adult cuticular structures. However, the morphologically abnormal discs contained both regions that maintained the normal monolayer epithelium and regions that had lost the normal tissue architecture. The implants obtained when the morphologically abnormal discs are injected into metamorphosing larvae contained only a limited number of the normal complement of adult structures and usually only structures found in the ventral wing hinge region were recovered. In addition, the “metamorphosed” morphologically abnormal discs contained undifferentiated tissue that gave rise to transplantable neoplasms when cultured in adults. The results of the studies on the pathology of thel(2)gl tslarvae are discussed with respect to the role of thel(2)gl tsfunction during normal development, the autonomy of the neoplastic development of thel(2)gl tstissues, and similarities between neoplastic development inDrosophila and mammals.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00848636
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  • 64
    Digitale Medien
    Digitale Medien
    Heterospecific combinations of germ cells and gonadal soma betweenDrosophila melanogaster, D. mauritiana andD. ananassae (1984)
    Springer
    Development genes and evolution 194 (1984), S. 99-106 
    Details
    ISSN: 1432-041X
    Schlagwort(e): Drosophila ; Pole cell transplantation ; Heterospecific combinations ; Gametogenesis ; Chorion morphology
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary We transplanted pole cells betweenDrosophila melanogaster, D. mauritiana andD. ananassae to investigate the ability of germ cells to develop in the gonad of a heterospecific host, and to study the interaction between somatic follicle cells and the cells of the germ line in producing the species-specific chorion. FemaleD. mauritiana germ cells in aD. melanogaster ovary produced functional eggs with normal development potential. The same is true for the reciprocal combination. FemaleD. ananassae pole cells in aD. melanogaster host only developed to a very early stage and degenerated afterwards. None of the interspecific combinations of male pole cells led to functional sperm. We could not determine at what stage the transplanted male pole cells were arrested. The cooperation of follicle cells and the oocyte-nurse cell complex in producing the chorion was studied using the germ-line-dependent mutationfs(1) K10 ofD. melanogaster, which causes fused respiratory appendages and an abnormal chorion morphology. Wild-type femaleD. mauritiana germ cells in a mutantfs(1) K10 D. melanogaster ovary led to the production of wild-type eggs withD. melanogaster-specific, short respiratory appendages. On the other hand,D. melanogaster fs(1) K10 germ cells in aD. mauritiana ovary induced the formation of eggs with mutant fused appendages which were, however, typicallyD. mauritiana in length. When.D. mauritiana pole cells developed in aD. melanogaster ovary, the chorion exhibited a new imprint pattern that differs from both species-specific patterns.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00848349
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  • 65
    Digitale Medien
    Digitale Medien
    Normal and lectin-mediated aggregation in aDrosophila cell line (1981)
    Springer
    Development genes and evolution 190 (1981), S. 118-122 
    Details
    ISSN: 1432-041X
    Schlagwort(e): Drosophila ; Aggregation ; Lectins ; Cell surface ; Embryo-derived cell line
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary In this paper we describe the aggregation of cells from embryo-derived cell lines ofDrosophila, measured by examining the ability of single cells to adhere to one another when suspended in culture medium and swirled on a rotary shaker. Using this method we demonstrated the presence of receptors for Concanavalin A, soybean agglutinin, and possibly wheat germ agglutinin on the surface of Schneider's line-2 cells. Our work provides basic descriptive and background information for further studies onDrosophila cells, including those isolated from imaginal discs.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00848405
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  • 66
    Digitale Medien
    Digitale Medien
    Evidence for myosin heterogeneity inDrosophila melanogaster (1981)
    Springer
    Development genes and evolution 190 (1981), S. 297-300 
    Details
    ISSN: 1432-041X
    Schlagwort(e): Myosins ; Drosophila ; muscle
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Electrophoresis of myosin extracts from larvae and adult tissues ofDrosophila melanogaster under non-dissociating conditions indicate that two of the bands seen are myosins. They stain for Ca2+ ATPase activity and when cut and re-run under dissociating conditions are found to contain a myosin heavy chain that co-migrates with rabbit skeletal muscle myosin heavy chain. One of the forms of myosin seen is found primarily in extracts from the leg. The other is common to the adult fibrillar flight muscles and the larval body wall muscles. The electrophoretic evidence for two myosin types is strengthened by the histochemical demonstration of two myofibrillar ATPases on the basis of their lability to acid or alkali preincubation. The myofibrillar ATPase in the leg and the Tergal Depressor of the Trochanter (TDT) are shown to be relatively acid labile and alkali stable. The larval body wall muscles and the adult fibrillar flight muscles have an ATPase which is acid stable and alkali labile. This distribution of the two myofibrillar ATPase coincides with that predicted by electrophoresis of extracts from whole tissue and also locates the two myosins to specific muscle types.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00848758
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  • 67
    Digitale Medien
    Digitale Medien
    Wound healing and regeneration in the imaginal wing disc ofDrosophila (1981)
    Springer
    Development genes and evolution 190 (1981), S. 185-190 
    Details
    ISSN: 1432-041X
    Schlagwort(e): Wound healing ; Regeneration ; Imaginal discs ; Drosophila
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary When complementary fragments of an imaginal disc ofDrosophila are cultured for several days prior to metamorphosis, usually one fragment will regenerate while the other will duplicate. It has been proposed that wound healing plays an important part in disc regulation (French et al. 1976; Reinhardt et al. 1977) by initiating cell proliferation and determining the mode of regulation. We tried to delay the wound healing process by leaving a region of dead cells between the wound edges. In “06” fragments (Bryant 1975a) wound healing has occurred after 1–2 days of culture and the regeneration of missing structures after 2–4 days of culture. We observed that leaving a region of dead cells between the wound edges delays both wound healing and the regeneration of missing structures by 2 days. When disc fragments are cultured in female abdomens and then exposed to3H-thymidine to label replicating cells, then the label is found to be localised around the wound. We observed that delaying wound healing does not delay this localisation of labelled nuclei indicating that wound healing may not be required to initiate DNA replication.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00848301
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  • 68
    Digitale Medien
    Digitale Medien
    Transdetermination in leg imaginal discs ofDrosophila melanogaster undDrosophila nigromelanica (1981)
    Springer
    Development genes and evolution 190 (1981), S. 156-160 
    Details
    ISSN: 1432-041X
    Schlagwort(e): Drosophila ; Imaginal discs ; Transdetermination ; Homeosis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The transdetermination capacities of leg discs ofDrosophila melanogaster were examined by mechanically disrupting and kneading whole discs from late third instar larvae and by culturing the resulting tissue mass for 10–14 days in adult female abdomens where the cells continued to divide. The grown implants were then dissected from the abdomens and injected into third instar larvae to undergo metamorphosis. After this treatment, prothoracic leg discs ofDrosophila melanogaster transdetermined with a high frequency (59% of all implants) to wing. Mesothoracic leg discs also transdetermined to wing, but at a very low frequency (4%). Metathoracic leg discs exhibited the same low frequency of transdetermination (4%), but in this case the direction of transdetermination was to haltere (Table 1,D. melanogaster). Very similar results were obtained with leg discs ofDrosophila nigromelanica (Table 1,D. nigromelanica), showing that the peculiar behavior of the three leg discs is not unique forDrosophila melanogaster. The homeotic mutation Polycomb (Pc 3) which partially transforms meso- and metathoracic legs into prothoracic legs did not significantly increase the frequencies of transdetermination in these leg dises and had clearly no effect on the direction of transdetermination (Table 1).
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00867802
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  • 69
    Digitale Medien
    Digitale Medien
    Correlation between adult transformation and aldehyde oxidase staining pattern in wing discs ofApterous genotypes inDrosophila melanogaster (1982)
    Springer
    Development genes and evolution 191 (1982), S. 285-288 
    Details
    ISSN: 1432-041X
    Schlagwort(e): Drosophila ; Imaginal discs ; homoeosis ; Compartments ; Aldehyde oxidase
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The aldehyde oxidase staining pattern in wing discs ofDrosophila melanogaster bearing the genotypesap blt /ap blt andap blt andap blt /ap 73n showns changes from the wild-type pattern. Extensive areas of the presumptive dorsal posterior wing blade, which are normally unstained, have enzyme activity in these mutants. In wings of these genotypes, dorsal posterior structures are replaced by dorsal anterior wing structures. A strong correlation has been found between the frequencies of various staining patterns in the discs and the extent of transformation in the cuticular structures of the wing, which is consistent with the idea that aldehyde oxidase activity can be used as an indicator in the wing disc of this transformation. Unlike the homoeotic mutationengrailed, apterous has not been interpreted as a selector gene yet the work reported here shows thatapterous alleles can cause changes resembling those of theengrailed phenotype both in aldehyde oxidase staining behaviour and in the cuticular transformation.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00848418
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  • 70
    Digitale Medien
    Digitale Medien
    Effects of the “sexcombless” chromosome (In(1)sx) on males and females ofDrosophila melanogaster (1982)
    Springer
    Development genes and evolution 191 (1982), S. 264-269 
    Details
    ISSN: 1432-041X
    Schlagwort(e): Drosophila ; Sexcombless ; Foreleg basitarsus ; Genital disc
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The chromosome which carries the mutationsexcombless (In(1)sx) affects males and females ofD. melanogaster. In the male foreleg basitarsi the number of sexcomb teeth is dramatically reduced from 10 to 0.7 and the number of transverse rows of bristles is increased from 6 to 8. Females homozygous forIn(1)sx show a normal bristle pattern in the foreleg basitarsus. The genital disc derivatives of both male and femaleIn(1)sx flies are strongly affected. While the external genitalia show a duplicated or a reduced bristle pattern, the internal genitalia are mostly absent. However, the sexually dimorphic tergites and sternites of the abdomen remain unaffected. The male-specific effect on the basitarsus and the general effects on the genital disc derivatives are proposed to represent two different phenotypic effects ofIn(1)sx which may derive from mutations at different gene loci in the inverted chromosome.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00848414
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  • 71
    Digitale Medien
    Digitale Medien
    Growth is required for cell competition in the imaginal discs ofDrosophila melanogaster (1982)
    Springer
    Development genes and evolution 191 (1982), S. 289-291 
    Details
    ISSN: 1432-041X
    Schlagwort(e): Drosophila ; Imaginal discs ; Cell competition
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Imaginal wing discs from late third-instar larvae were gammairradiated to induce clones of rapidly growingMinute − cells in a background of slowly growingMinute cells and culturedin vivo for periods up to 18 days. Clones in discs cultured for 16 to 18 days did not grow significantly larger than clones in uncultured controls, indicating that competition between populations of cells having potentially different mitotic rates does not occur in imaginal discs after their growth is completed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00848419
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  • 72
    Digitale Medien
    Digitale Medien
    Isolation and characterization of temperature-sensitivelethal(2)giant larva alleles (1984)
    Springer
    Development genes and evolution 193 (1984), S. 98-107 
    Details
    ISSN: 1432-041X
    Schlagwort(e): Drosophila ; Neoplasms ; Promotion ; Regeneration ; Temperature-sensitive ; Imaginal discs
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary In this paper we present an analysis of the behavior ofl(2)gl tsimaginal wing discs during culture in adult hosts. Thel(2)gl tslarvae reared at 29° C contain two types of wing discs, those that are morphologically normal and those that are abnormal. When discs of both types are cultured in adult hosts at 29° C, the restrictive temperature, they give rise to transplantable neoplastic tissue. However, when the 29° C reared discs are cultured at 15° C, the permissive temperature, the morphologically normal discs maintain their morphology, but the morphologically abnormal discs give rise to neoplasms. Thel(2)gl tslarvae reared at 15° C contain only morphologically normal discs. When these discs are cultured in adult hosts at 29° C they give rise to neoplasms, however if the discs are cultured at 15° C they maintain their normal morphology. These results demonstrate: (1) that all wing imaginal discs obtained from 29° C rearedl(2)gl tslarvae are competent to undergo neoplastic development, (2) the morphologically abnormal discs obtained from the 29° C rearedl(2)gl tslarvae are committed to neoplastic development, (3) the neoplastic development of the morphologically normal discs is temperature dependent, (4) once the neoplastic development of thel(2)gl tsdiscs has been initiated the process is not readily reversible. In addition, the ability ofl(2)gl tswing discs to perform epimorphic regulation was tested by amputating morphologically normal permissively rearedl(2)gl tswing discs and culturing both fragiments at the permissive temperature. Fragments of control wild-type discs maintained their morphology during culture at the permissive temperature. However, both fragments of txel(2)gl tsdiscs became neoplastic. This result is discussed with respect to a possible role for thel(2)gl +function in epimorphic regulation and with respect to the phenomena of tumor promotion in vertebrates.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00848637
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  • 73
    Digitale Medien
    Digitale Medien
    Sequential gene activation by ecdysteroids in polytene chromosomes ofDrosophila melanogaster (1982)
    Springer
    Development genes and evolution 191 (1982), S. 103-111 
    Details
    ISSN: 1432-041X
    Schlagwort(e): Drosophila ; Polytene Chromosomes ; Ecdysteroids ; Fat Body
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Changes in polytene chromosome 3 L puffing patterns in the fat body ofDrosophila melanogaster larvae and prepupae are compared to those in the salivary gland. While some general features are common to the two tissues, there are differences which reflect their different developmental roles. In vitro experiments with fat body chromosomes show that they have a distinct response to ecdysteroids which is different from that of salivary gland chromosomes, and which does not,in this culture system, reproduce the changes observed in normal development. In short term culture experiments, the fat body chromosomes appear more sensitive to ecdysteroids than the salivary gland chromosomes and, although 20-OH ecdysone is more active than ecdysone in these assays, the possibility is not excluded that ecdysone has a role in normal development as it appears to alter gene activity at physiological levels in these cells.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00848447
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  • 74
    Digitale Medien
    Digitale Medien
    Homologies of positional information in thoracic imaginal discs ofDrosophila melanogaster (1982)
    Springer
    Development genes and evolution 191 (1982), S. 293-300 
    Details
    ISSN: 1432-041X
    Schlagwort(e): Drosophila ; Imaginal discs ; Positional information ; Homology ; Intercalary regeneration
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The regulative behavior of fragments of the imaginal discs of the wing and first leg was studied when these fragments were combined with fragments of other thoracic imaginal discs. A fragment of the wing disc which does not normally regenerate when cultured could be stimulated to regenerate by combination with certain fragments of the haltere disc. When combined with a haltere disc fragment thought to be homologous by the criteria of morphology and the pattern of homoeotic transformation, such stimulated intercalary regeneration was not observed. Combinations of first and second leg disc fragments showed that a lateral first leg fragment could be stimulated to regenerate medial structures when combined with a medial second leg disc fragment but not when combined with a lateral second leg disc fragment. Combinations of wing and second leg disc fragments showed that one fragment of the second leg disc is capable of stimulating regeneration from a wing disc fragment while another second leg disc fragment fails to stimulate such regeneration. It is suggested that absence of intercalary regeneration in combinations of fragments of different thoracic imaginal discs is a result of homology or identity of the positional information residing in the cells of the fragments. The pattern of correspondence of positional information revealed by this analysis is consistant with the pattern of homology determined by morphological observation and by analysis of the positional specificity of homoeotic transformation among serially homologous appendages. The implications of the existence of homologous positional information in wing and second leg discs which share a common cell lineage early in development are discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00848488
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  • 75
    Digitale Medien
    Digitale Medien
    Gap junctions are non-randomly distributed inDrosophila wing discs (1982)
    Springer
    Development genes and evolution 191 (1982), S. 335-339 
    Details
    ISSN: 1432-041X
    Schlagwort(e): Drosophila ; Gap junction ; Wing disc
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The distribution of gap junctions in mature larvalDrosophila melanogaster wing discs was analyzed by means of quantitative electron microscopy. Gap junctions are non-randomly distributed in the proximal-distal disc axis and in the apical-basal cell axis of the epithelium. In the epithelial cells, the surface density, number and length of gap junctions are greatest in the apical cell region and distal disc region. The average gap junction surface density is 0.0572 μm−1 and 2.77% of the lateral cell surface is composed of gap junctions. In the adepithelial cells, the gap junction surface density is 0.0005 μm−1 and 0.06% of the cell surface is composed of gap junctions. No gap junctions were observed between epithelial cells and adepithelial cells. The absolute area of gap junctions was estimated in a proximal-distal strip of cells in the disc and is considerably less in the folded regions of the epithelium compared to the flat notum and wing pouch regions. The results are discussed with respect to pattern formation and growth control in imaginal discs.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00848494
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  • 76
    Digitale Medien
    Digitale Medien
    Imaginal disc development in a non-pupariating lethal mutant inDrosophila melanogaster (1981)
    Springer
    Development genes and evolution 190 (1981), S. 11-21 
    Details
    ISSN: 1432-041X
    Schlagwort(e): Drosophila ; Imaginal discs ; Ecdysteroid ; Lethal mutant ; Morphogenesis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Imaginal disc development in the non-pupariating lethall(1)npr-1, a mutant that maps to an ecdysone early puff site, is studied in situ, in vitro and in transplanted discs. Disc development is slightly abnormal from the middle of the third instar with severe abnormalities appearing after the rise in 20-hydroxyecdysone that triggers metamorphosis. The mutant discs only partly evaginate and do not undergo any of the detailed morphological changes characteristic of metamorphosis. Treatment of the mutant dises in vitro with colcemid and trypsin facilitates evagination but the appendages remain morphologically abnormal. A number of differentiative processes occur in mutant discs in situ and in discs transplanted into wild type hosts in spite of the absence of normal morphogenesis. Implications of the observations for normal disc development are discussed. Possible modes of action of thel(1)npr-1 gene are also discussed in light of the observation that the mutant gene maps to a locus which is thought to have a regulatory function in development.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00868698
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  • 77
    Digitale Medien
    Digitale Medien
    A maternal effect mutation leading to deficiencies of organs and homeotic transformations in the adults ofDrosophila (1981)
    Springer
    Development genes and evolution 190 (1981), S. 132-138 
    Details
    ISSN: 1432-041X
    Schlagwort(e): Maternal effect mutant ; Homeotic-mutants ; Pattern formation ; Drosophila
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The temperature sensitive mutationfs(l)h is characterized at the restrictive temperature of 29°C by both a maternal effect responsible for the early embryonic lethality and pupal zygotic lethality. The two phenotypes are inseparable and map at a short deletion in the X chromosome (7Dl, 7D5-6). At semipermissive temperatures, hemizygous mutant females produce adults with morphological defects, such as organ deficiencies and homeotic transformations of haltere to wing and third leg to second leg. These defects depend on the maternal genotype and are governed by an early temperature sensitive period, which covers the end of oogenesis and the first hours of embryogenesis. Furthermore, this maternal effect mutation interacts with some dominant mutations of the bithorax system. These properties suggest thatfs(l)h is somehow involved in segmental determination.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00867798
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  • 78
    Digitale Medien
    Digitale Medien
    Isolation and characterization ofgrandchildless-like mutants inDrosophila melanogaster (1981)
    Springer
    Development genes and evolution 190 (1981), S. 1-10 
    Details
    ISSN: 1432-041X
    Schlagwort(e): Drosophila ; Grandchildless ; Pole cells ; ts-mutant ; Cytoplasmic determinant
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Two temperature-sensitive sex-linkedgrandchildless (gs)-like mutations (gs(1)N26 andgs(1)N441) were induced by ethylmethane sulphonate inDrosophila melanogaster. They complemented each other and mapped at two different loci (1−33.8±0.7 forgs(1)N26 and 1−39.6±1.7 forgs(1)N441), which were not identical to those of any of thegs-like mutants reported in earlier work. Homozygous females of the newly isolated mutants produced eggs that were unable to form pole cells and developed into agametic adults. Competence of the embryos to form pole cells was not restored by wild-type sperm in either mutant; that is, the sterility caused by these mutations is controlled by a maternal effect. Fecundity and fertility ofgs(1)N26 females were low, and their male offspring showed a higher mortality than that of female offspring, causing an abnormal sex ratio. The frequency of agametic progeny was 93.1% and 55.8%, when the female parents were reared at 25° C and 18° C, respectively. In eggs produced by thegs(1)N26 females reared at 25° C, the migration of nuclei to the posterior pole was abnormal, and almost no pole cell formation occurred in these egg. Furthermore, half of these eggs failed to cellularize at the posterior pole. When the females were reared at 18° C, almost all of the eggs underwent complete blastoderm formation, and in half of these blastoderm embryos normal pole cells were formed. In the other mutant,gs(1)N441, the fecundity and fertility of the females were normal. The agametic frequency in the progeny was 70.8% and 18.6% when the female parents were reared at 25° C and 18° C, respectively. In the eggs laid by females reared either at 25° C or at 18° C, the migration of nuclei to the periphery and cellularization proceeded normally; nevertheless, in the majority of the embryos no pole cell formation occured at the stage when nuclei penetrated into the periplasm. When the females were reared at 18° C, some of the embryos from these females formed some round blastoderm cells with cytologically recognizable polar granules and nuclear bodies, which are attributes of pole cells. The temperature sensitive period ofgs(1)N441 was estimated to extend from stage 9 to 13 of King's stages of oogenesis.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00868697
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  • 79
    Digitale Medien
    Digitale Medien
    Effect of the l(1)su(f)ts67g mutation ofDrosophila melanogaster on glue protein synthesis (1981)
    Springer
    Development genes and evolution 190 (1981), S. 308-312 
    Details
    ISSN: 1432-041X
    Schlagwort(e): Drosophila ; ts-Suppressor mutant ; Glue proteins ; Intermolt puffs ; Electrophoresis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The l(1)su(f)ts67g mutation has been shown to suppress the developmentally regulated expression of glue protein genes at 30°C. Transferring mutant larvae to the restrictive temperature before the end of the second larval instar results in the absence or extreme reduction of glue protein synthesis while general protein synthesis is unaffected. At the same time, the three glue protein correlated chromosomal regions 3C, 25B, and 68C continue to show prominent puffs. The results suggest that the mutation may be affecting the processing or translatability of specific mRNAs rather than the translational machinery itself.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00863267
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  • 80
    Digitale Medien
    Digitale Medien
    Dicephalic — ADrosophila mutant affecting polarity in follicle organization and embryonic patterning (1982)
    Springer
    Development genes and evolution 191 (1982), S. 28-36 
    Details
    ISSN: 1432-041X
    Schlagwort(e): Drosophila ; Polarity ; Maternal effect ; Nurse cells ; Embryogenesis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The mutationdicephalic (dic) affects follicle development and thereby alters the antero-posterior polarity of embryonic patterning. It maps at a single locus (3–46.0±1.0) and can be characterized as a semi-dominant maternal effect mutation with low penetrance. Indic follicles, the 15 nurse cells form two clusters located at opposite poles of the oocyte; the numerical distribution of the nurse cells among the clusters varies from 7:8 to 1:14. Thedic egg shell carries a micropyle (anterior marker) at either pole, but the misshapen respiratory appendages are restricted to one of the two poles in most eggs. The malformed eggs rarely yield larvae and these are always abnormal anteriorly and/or posteriorly. The segment pattern expressed in their cuticle may represent two anterior parts of opposite polarities (double head type), two posterior parts of opposite polarities (double abdomen type, rare) or show uniform polarity. Lability of organization at the cystocyte stage appears as the primary developmental defect of the mutant.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00848543
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  • 81
    Digitale Medien
    Digitale Medien
    Changes in the distribution of gap junctions inDrosophila melanogaster wing discs during the third larval and early pupal stages of development (1984)
    Springer
    Development genes and evolution 193 (1984), S. 187-196 
    Details
    ISSN: 1432-041X
    Schlagwort(e): Drosophila ; Gap junction ; Imaginal disc ; Pattern formation ; EM Stereology
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Developmental changes in the distribution of gap junctions in early, mid and late third larval stage wing discs and in pupariation+6 h and pupariation+24 h stage wing discs fromDrosophila melanogaster were analyzed by quantitative electron microscopy. Gap junctions occur in all 12 intradisc regions examined in each of the five developmental stages. Their distribution is non-random and changes during development which suggests that they are developmentally regulated. The gap junctions are not static structures, rather they grow and regress during development. The changes tend to be gradual ones without sudden increases or decreases. Gap junctions continuously form and grow in size throughout the third larval stage and during the first 6 h following pupariation. Their surface density, number, percent of the lateral plasma membrane area, and absolute area as well as the lateral plasma membrane surface density all increase during this time. Between pupariation+ 6 h and pupariation+24 h all but one of these parameters decrease indicative of gap junctional breakdown. Gap junctions are most numerous and change least during development in the apical cell regions where intercellular contacts are close and stable. They change most in the basal cell regions where intercellular contacts tend to be looser and change during development. The most dramatic change is in the absolute area which increases by a factor of 23 between the early third larval stage and pupariation+24 h. At pupariation the rate of gap junction growth undergoes a transient increase before the phase of disassembly begins. Developmental changes in gap junction surface density are closely coupled with changes in the lateral plasma membrane surface density which suggests that these may be coregulated. Evidence from mutants suggests that when the number and density of gap junctions fail to increase in proportion to lateral plasma membrane growth, wing disc development will be abnormal. Our results support the idea that some minimum gap junction density is required for normal development and that this must increase as development proceeds. The results are consistent with the notion that gap junctions are involved in pattern formation and growth control and are discussed with respect to the acquisition of competence for metamorphosis, disc growth, disc morphogenesis and changes in the hormonal environment.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01260338
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  • 82
    Digitale Medien
    Digitale Medien
    Immunocytochemical and electrophoretic studies on the localization of the major haemolymph proteins (ceratitins) inCeratitis capitata during development (1984)
    Springer
    Development genes and evolution 194 (1984), S. 37-43 
    Details
    ISSN: 1432-041X
    Schlagwort(e): Major haemolymph proteins ; Development ; Cuticle ; Immunocytochemistry ; Ceratitis capitata
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The developmental profile of the major haemolymph proteins (ceratitins) inCeratitis capitata was studied. Ceratitin concentration in the haemolymph decreases dramatically during the last days of pupal life, while the amounts of ceratitins in whole organism extracts remain unchanged. By electrophoretic, immunological and immunofluorescence techniques it was revealed that ceratitins are reabsorbed by the fat body and a fraction of them is deposited in the cuticle. The possible role of ceratitins is discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00848952
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  • 83
    Digitale Medien
    Digitale Medien
    Drosophila melanogaster eggshell development: Localization of the s19 chorion gene (1981)
    Springer
    Development genes and evolution 190 (1981), S. 301-303 
    Details
    ISSN: 1432-041X
    Schlagwort(e): Drosophila ; Geographic strains ; Chorion genes ; Electrophoretic variants
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Further IF screening ofDrosophila melanogaster geographic strains has revealed a variant of the s19 major chorion protein. Developmental analysis of F1 hybrids indicates that the source of the variation is found in the structural gene for this protein. The linkage group of the variant gene was determined to be the third, and the gene was localized by several methods of recombination analysis. The s19 gene was found to be tightly linked to thesepia locus, as had been previously found for the s18 gene (Yannoni and Petri 1980). Lack of recombination between the s19 and s18 genes in double heterozygotes suggested that these two genes are within 0.3 map units of each other. Although more precise localization of the s19 gene failed, the s18 gene could be more specifically located to the right ofsepia, betweensepia andhairy. Contrary to our prediction (ibid.), the s19 and s18 genes have been found to be tightly linked in spite of the fact that they display somewhat different developmental stage specificity.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00848759
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  • 84
    Digitale Medien
    Digitale Medien
    A cell arrangement specific to thoracic ganglia in the central nervous system of theDrosophila embryo: Its behaviour in homoeotic mutants (1981)
    Springer
    Development genes and evolution 190 (1981), S. 370-373 
    Details
    ISSN: 1432-041X
    Schlagwort(e): Drosophila ; Homoeotic mutants ; Ventral cord
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary We describe a set of cells in the central nervous system of theDrosophila embryo which are restricted to the thoracic ganglia in the wildtype. Taking these cells as indication of thoracic identity, we find that the ventral cord of embryos homozygous mutant for different bithorax functions and for Polycomb undergoes homoeotic transformations equivalent to those observed in the larval cuticle.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00863276
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  • 85
    Digitale Medien
    Digitale Medien
    A clonal analysis of cell lineage and growth in the male and female genital disc ofDrosophila melanogaster (1982)
    Springer
    Development genes and evolution 191 (1982), S. 42-55 
    Details
    ISSN: 1432-041X
    Schlagwort(e): Clonal analysis ; Growth ; Cell lineage ; Genital disc ; Drosophila
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary InDrosophila, the terminalia (i.e. internal and external analia and genitalia, except the gonads) are formed by the genital disc. Comparative studies suggested that this disc may have evolved through fusion of the imaginal primordia of the last 3 or 4 abdominal segments. The present report describes the clonal relationships within the complex genital disc. Genetically marked cell clones were induced in male and female embryos and larvae heterozygous for cell marker mutations. 1) Frequencies and sizes of clones suggest that the embryonic disc anlage consists of 14–17 precursor cells: 4–6 for the analia, some 7 for the male genitalia, and 3–4 for the female genitalia. These cells grow exponentially during larval development. 2) In both sexes, the clones were confined to either analia or genitalia, suggesting two separate cell lineages already established at blastoderm. 3) Internal and external genitalia remain in the same compartment at least up to 60 h (end of first instar). 4) A clonal restriction appeared around 84 h (mid second instar), separating a dorsal from a ventral part in the male genitalia. The ventral compartment comprises the ventral part of the lateral plate and clasper, hypandrium, and all internal genitalia. No such boundary was detected in the female. 5) In the female, analia and parovaria originate from the same precursors; another cell lineage forms eighth tergites, vaginal plates, oviduct, receptacle, and spermathecae. 6) In female analia, dorsal and ventral plate share common precursors at least up to 84 h. A medio-lateral boundary may appear at 84 h in the ventral anal plate. No clonal restriction was found in the male analia. 7) At all times, clones could cross between left and right sides of the symmetrical terminalia; they consistently did so via ventral structures. 8) The results are discussed in a phylogenetic context, and we propose that the clonal relations reflect the evolution of the complex genital disc.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00848545
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  • 86
    Digitale Medien
    Digitale Medien
    Maternal effects of zygotic mutants affecting early neurogenesis inDrosophila (1982)
    Springer
    Development genes and evolution 191 (1982), S. 191-201 
    Details
    ISSN: 1432-041X
    Schlagwort(e): Neurogenic mutants ; Maternal effects ; Drosophila
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The size of the neurogenic region ofDrosophila melanogaster is under the control of several genes of zygotic expression. Lack of function from any of those genes produces an increase of the size of the neurogenic region at the expense of the epidermal anlage. However, differences exist in the extent of neuralisation achieved by each of the genetic loci upon mutation. The present results show that in the case ofN andmam phenotype differences are due to different contributions of maternal gene expression. This could be shown by studying the phenotype which appeared in mutant embryos when the oocytes developed from homozygous mutant precursor cells. Clones of mutant cells were induced in the germ line of females heterozygous for the neurogenic mutationin trans over germ line dependent, dominant female sterile mutations. After removing maternal information the phenotype ofN andmam mutants became identical in both cases. Furthermore maternal information fromN + was found to be necessary for viability of the wildtype.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00848335
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  • 87
    Digitale Medien
    Digitale Medien
    Clonal analysis ofsex-lethal, a gene needed for female sexual development inDrosophila melanogaster (1982)
    Springer
    Development genes and evolution 191 (1982), S. 211-214 
    Details
    ISSN: 1432-041X
    Schlagwort(e): Drosophila ; Clonal analysis ; Sex determination
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The mutationSxl f , located on the X-chromosome, is a sex-limited recessive lethal that specifically kills 2X; 2A flies while it does not affect X; 2A flies (Cline 1978). We have analyzed the role ofSxl f on sex determination by a clonal analysis of a new spontaneous allele,Sxl fLS . Female embryos and larvae heterozygous forSxl fLS were irradiated at different times of development to generate homozygousSxl fLS clones which were recognized by linked marker mutations. We have studied the phenotype of such clones on sexually dimorphic regions of the fly (foreleg basitarsus, 5th, 6th and 7th tergites, analia and external genitalia). Despite their female (2X; 2A) chromosomal constitution, clones homozygous forSxl fLS differentiated male structures. These results confirm and extend the preliminary report of Cline (1979). They show that the wildtype product ofSxl f is required for female development.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00848339
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  • 88
    Digitale Medien
    Digitale Medien
    Mutations affecting the pattern of the larval cuticle inDrosophila melanogaster (1984)
    Springer
    Development genes and evolution 193 (1984), S. 296-307 
    Details
    ISSN: 1432-041X
    Schlagwort(e): Drosophila ; Larval cuticle ; Pattern formation ; Embryonic lethal mutations
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary In order to identify X-chromosomal genes required inDrosophila for early patterning and morphogenesis, we examined embryos hemizygous for EMS-induced lethal mutations to determine which of those mutations cause gross morphological defects. Embryos from 2711 lethal lines, corresponding to 3255 lethal point mutations were studied. Only 21% caused death during embryogenesis and of these, only one-sixth, or 3% of the total lethals, were associated with defects visible in the final cuticle pattern. Of the 114 point mutants causing visible cuticle defects, 76 could be assigned to 14 complementation groups. An additional 25 mutations mapping to regions of the X-chromosome not covered by male fertile duplications were assigned to six complementation groups based on similarities of map position and phenotype. Thirteen mutations could not be assigned to complementation groups. All mutations allowed normal development through the cellular blastoderm stage, the first defects associated with the earliest acting loci being observed shortly after the onset of gastrulation. The phenotypes of the various loci range from alterations in segment pattern or early morphogenetic movements to defects in final pigmentation and denticle morphology. Cuticle preparations were also examined for 63 deletions spanning in total 74% of the X-chromosome, as well as for 8 deletions and point mutations derived in saturation mutagenesis screens of the fourth chromosome (Hochman 1976). With the exception of defects in head morphology and defects in cuticle differentiation, none of the hemizygous deletions showed phenotypes other than those predicted by point mutations known to lie in those regions. No deletion caused new or unknown alterations in gastrulation, segmentation or cuticle pattern.These results suggest that the number of genes required zygotically for normal embryonic patterning is small and that most, if not all such loci, are represented by point mutations in our collection.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00848158
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  • 89
    Digitale Medien
    Digitale Medien
    The role of the peripodial membrane of leg and wing imaginal discs ofDrosophila melanogaster during evagination and differentiation in vitro (1984)
    Springer
    Development genes and evolution 193 (1984), S. 180-186 
    Details
    ISSN: 1432-041X
    Schlagwort(e): Drosophila ; Imaginal disc ; Morphogenesis ; Tissue culture
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The thin region of the peripodial membrane is confined to the area overlying the distal anlagen in thoracic discs. During the early stages of evagination the peripodial membrane is greatly stretched, but does not rupture. The appendage then evaginates through the stalk, probably by means of a contraction of the peripodial membrane. The cells of the peripodial membrane of leg and wing discs persist and differentiate sheets of trichomes characteristic of the ventral and lateral thorax. This is discussed in relation to imaginal disc fate maps.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00848893
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  • 90
    Digitale Medien
    Digitale Medien
    TheUbx syndrome ofDrosophila: the prothoracic transformation (ppx) is independent ofbx, bxd andpbx (1984)
    Springer
    Development genes and evolution 193 (1984), S. 263-265 
    Details
    ISSN: 1432-041X
    Schlagwort(e): Drosophila ; Biothorax complex ; Prothoracic transformation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary If, early in development, theUbx + gene is removed by mitotic recombination from cells of the meso-and metathoracic leg primordia, theseUbx − cells develop as in the posterior prothoracic leg. We show that this transformation, termedpostprothorax, is a discrete genetic function that is independent of other homeotic transformations such asbx, pbx orbxd, which also result from the inactivation of theUbx gene.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01260349
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  • 91
    Digitale Medien
    Digitale Medien
    Mutations affecting the pattern of the larval cuticle inDrosophila melanogaster (1984)
    Springer
    Development genes and evolution 193 (1984), S. 283-295 
    Details
    ISSN: 1432-041X
    Schlagwort(e): Drosophila ; Larval cuticle ; Pattern formation ; Embryonic lethal mutations
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The present report describes the recovery and genetic characterization of mutant alleles at zygotic loci on the third chromosome ofDrosophila melanogaster which alter the morphology of the larval cuticle. We derived 12600 single lines from ethyl methane sulfonate (EMS)-treatedst e orrucuca chromosomes and assayed them for embryonic lethal mutations by estimating hatch rates of egg collections. About 7100 of these lines yielded at least a quarter of unhatched eggs and were then scored for embryonic phenotypes. Through microscopic examination of unhatched eggs 1772 lines corresponding to 24% of all lethal hits were classified as embryonic lethal. In 198 lines (2.7% of all lethal hits), mutant embryos showed distinct abnormalities of the larval cuticle. These embryonic visible mutants define 45 loci by complementation analysis. For 32 loci, more than one mutant allele was recovered, with an average of 5.8 alleles per locus. Complementation of all other mutants was shown by 13 mutants. The genes were localized on the genetic map by recombination analysis, as well as cytologically by complementation analysis with deficiencies. They appear to be randomly distributed along the chromosome. Allele frequencies and comparisons with deficiency phenotypes indicate that the 45 loci represent most, if not all, zygotic loci on the third chromosome, where lack of function recognizably affects the morphology of the larval cuticle.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00848157
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  • 92
    Digitale Medien
    Digitale Medien
    Early neurogenesis in wild-typeDrosophila melanogaster (1984)
    Springer
    Development genes and evolution 193 (1984), S. 308-325 
    Details
    ISSN: 1432-041X
    Schlagwort(e): Neurogenesis ; Pattern of neuroblasts ; Drosophila
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary This paper deals with morphological aspects of early neurogenesis inDrosophila, in particular with the segregation of neuroblasts from the neurogenic region of the ectoderm and the pattern formed by those wells within both the germ band and the procephalic lobe. The neurogenic ectoderm was found to contain neural precursors intermingled with epidermal precursors, extending from the midline up to the primordia of the tracheal tree along the germ band and laterodorsally in the procephalic lobe. Germ band neuroblasts segregate from the neurogenic ectoderm during a period of several hours according to characteristic spatial and temporal patterns. During the first half of the segregation process the pattern of germ band neuroblasts was found to be the same in different animals in both spatial arrangement and number of cells; this permitted the identification of individual neuroblasts from different embryos. Later in development several difficulties were encountered which precluded an exact description of the neuroblast pattern. The constitution of the neurogenic region is discussed in relation to the phenotype of mutants affecting neurogenesis.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00848159
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  • 93
    Digitale Medien
    Digitale Medien
    The spatial arrangement of germ line cells in ovarian follicles of the mutantdicephalic inDrosophila melanogaster (1984)
    Springer
    Development genes and evolution 193 (1984), S. 388-393 
    Details
    ISSN: 1432-041X
    Schlagwort(e): Drosophila ; Oogenesis ; Ring canals ; Oocyte determination ; Polarity
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The pattern of intercellular connections between germ line cells has been studied in follicles of the mutantdicephalic (dic), which possess nurse cell clusters at both poles. Staining of follicles with a fluorescent rhodamine conjugate of phalloidin reveals ring canals and cell membranes and thus allows us to reconstruct the spatial organization of the follicle. Each germ line cell can be identified by the pattern of cell-cell connections which reflect the mitotic history of individual cells in the 16-cell cluster. The results indicate that in both wild-type anddicephalic cystocyte clusters one of the two cells with four ring canals normally becomes the pro-oocyte. However, in some follicles (dicephalic and wild-type) oocytes were found with fewer or more than four ring canals. Indic follicles, one or several nurse cells may become disconnected from the other cells during oocyte growth at stage 9–10. Such disconnected cells cannot later on empty their cytoplasm into the oocyte. This, in turn, might be of consequence for the determination of axial polarity of the embryo.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00848229
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  • 94
    Digitale Medien
    Digitale Medien
    Cell interactions during the fusionin vitro ofDrosophila eye-antennal imaginal discs (1984)
    Springer
    Development genes and evolution 193 (1984), S. 406-413 
    Details
    ISSN: 1432-041X
    Schlagwort(e): Drosophila ; Imaginal disc ; Morphogenesis ; Tissue culture
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The fusion of the eye-antennal discs during culturein vitro has been investigated, and the complex morphogenetic movements which occur during the formation of the head capsule of the insect are described. The initial contact between the eye anlagen is by means of cell processes spanning the gap between the two discs. Subsequently the two epithelia become firmly apposed, and then the integrity of the epithelium in the region of fusion breaks down, cells appearing to move to new positions in order to form an epithelium which unites the two discs. The epithelium eventually secretes a pattern of cuticular structures which is continuous between the derivatives of the two discs. Bristles on either side of the line of fusion are perfectly aligned, and structures such as the median ocellus, which are formed jointly by the cells of the two discs, differentiate normally. This is also found when left and right eye-antennal discs of different genotypes are placed side-by-side, indicating that processes of pattern regulation can occur in culture.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00848232
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  • 95
    Digitale Medien
    Digitale Medien
    Localization of phytohemagglutinin in the embryonic axis of Phaseolus vulgaris with ultra-thin cryosections embedded in plastic after indirect immunolabeling (1984)
    Springer
    Planta 162 (1984), S. 548-555 
    Details
    ISSN: 1432-2048
    Schlagwort(e): Immunocytochemistry ; Lectin (localization) ; Phaseolus (lectin) ; Phytohemagglutinin ; Seed (lectin)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract We have examined the properties and subcellular localization of phytohemagglutinin (PHA), the major lectin of the common bean (Phaseolus vulgaris.), in the axis cells of nearly mature and imbibed mature seeds. On a protein basis the axis contained about 15% as much PHA as the cotyledons. Localization of PHA was done with an indirect immunolabeling method (rabbit antibodies against PHA, followed by colloidal gold particles coated with goat antibodies against rabbit immunoglobulins) on ultra-thin cryosections which were embedded in plastic on the grids after the immunolabeling procedure. The embedding greatly improved the visualization of the subcellular structures. The small (4 nm) collodial gold particles, localized with the electron microscope, were found exclusively over small vacuoles or protein bodies in all the cell types examined (cortical parenchyma cells, vascular-bundle cells, epidermal cells). The matrix of these vacuoles-protein bodies appears considerably less dense than that of the protein bodies in the cotyledons, but the results confirm that in all parts of the embryo PHA is localized in similar structures.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00399921
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  • 96
    Digitale Medien
    Digitale Medien
    On the cellular localization of phosphoenolpyruvate carboxylase in Sorghum leaves (1981)
    Springer
    Planta 151 (1981), S. 226-231 
    Details
    ISSN: 1432-2048
    Schlagwort(e): Immunocytochemistry ; (PEP carboxylase) ; PEP carboxylase ; Sorghum
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The localization of phosphoenol pyruvate carboxylase (EC 4.1.1.3.1.) in the leaf cells of Sorghum vulgare was investigated by using three techniques: the conventional aqueous and non aqueous methods gave conflicting results; the immunocytochemical techniques clearly showed that the enzyme is predominantly located in the cytoplasm of mesophyll cells.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00395173
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  • 97
    Digitale Medien
    Digitale Medien
    Tissue-specific and substrate-specific detection of aldehyde and pyridoxal oxidase in larval and imaginal tissues of Drosophila melanogaster (1982)
    Springer
    Biochemical genetics 20 (1982), S. 315-332 
    Details
    ISSN: 1573-4927
    Schlagwort(e): aldehyde oxidase ; pyridoxal oxidase ; tissue specificity ; Drosophila
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Abstract The substrate specificities of aldehyde and pyridoxal oxidases in Drosophila melanogaster have been determined with a variety of aliphatic and aromatic aldehydes. This analysis has led to the discovery that 2,4,5-trimethoxy-benzaldehyde is a specific substrate for pyridoxal oxidase, as based on the histochemical distribution of oxidase activity, the absence of enzymatic activity in the lpo 1strains, and the dosage dependence on the number of lpo +genes present. The tissue-specific localization of aldehyde oxidase (AO) and pyridoxal oxidase (PO) in the larval and adult structures showed that AO was present in all the major internal organs of the larvae and adults, including brain, imaginal discs, Malpighian tubules, digestive system, and reproductive structures. Pyridoxal oxidase is present in many of the same structures which possess AO, but is missing from the cardia, crop, imaginal discs, ovarian follicle cells, paragonia, pericardial cells, and wreath cells. The only structure which possesses PO but lacks AO is the larval salivary gland. These histochemical differences in AO and PO distribution were also confirmed by enzymatic analysis of the activities present in homogenates of ovaries, paragonia, and salivary glands. The general pattern of enzyme expression appears to be established during embryogenesis and maintained throughout the life of the individual.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00484427
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  • 98
    Digitale Medien
    Digitale Medien
    Selection at the α-Gpdh locus in experimental populations of Drosophila melanogaster (1982)
    Springer
    Biochemical genetics 20 (1982), S. 461-474 
    Details
    ISSN: 1573-4927
    Schlagwort(e): Drosophila ; allozymes ; α-Gpdh ; selection ; genetic background
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Abstract Three sets of experiments have been conducted in order to evaluate the role of natural selection at the α-Gpdh locus in Drosophila melanogaster. (1) The evolution of the F-allele frequency has been followed for many generations in 13 experimental populations having different genetic backgrounds. (2) Egg-to-adult viability has been measured in synthetic populations derived from one locality (Brouilly) and the results have been compared with those of a previous experiment involving a different local population (Tostes). (3) The effects of sodium octanoate on egg-to-adult viability have been measured on the genotypes FF, FS, SF, and SS. The results demonstrate that selection operates on a small block of genes which includes the α-Gpdh locus.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00484697
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  • 99
    Digitale Medien
    Digitale Medien
    An esterase duplication in Drosophila: Differences in expression of duplicate loci within and among related species (1982)
    Springer
    Biochemical genetics 20 (1982), S. 929-942 
    Details
    ISSN: 1573-4927
    Schlagwort(e): esterase ; duplication ; gene expression ; Drosophila
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Abstract An esterase duplication is described in the sibling species pair Drosophila mojavensis and Drosophila arizonensis. We present evidence for two separate structural loci mapping at a distance of less than 0.16 recombination units from each other. Alleles at the two loci have the same substrate specificities and form small amounts of interlocus heterodimers. One locus (Est-5) is functioning throughout the insect's life cycle and appears at high concentrations in the hemolymph and the fat body. Its duplicate (Est-4) functions only during the late larval stage and is concentrated mainly in the carcass. No null alleles at either locus were observed in population surveys. An examination of 12 other species from the repleta group, to which D. mojavensis and D. arizonesis belong, suggests that Est-5 is universally present, but the activity levels of Est-4 vary among species and may be totally absent in some species. Variation in the level of Est-4 activity does not closely follow the phylogenetic relationship.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00484070
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  • 100
    Digitale Medien
    Digitale Medien
    Aldehyde oxidases of Drosophila: Contributions of several enzymes to observed activity patterns (1981)
    Springer
    Biochemical genetics 19 (1981), S. 567-583 
    Details
    ISSN: 1573-4927
    Schlagwort(e): aldehyde oxidase ; Drosophila ; evolution ; gene regulation ; isozymes
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Abstract At least four enzymes contribute to histochemically, electrophoretically, or spectrophotometrically detectable aldehyde oxidase (AO) activity in Drosophila melanogaster. The one we designate AO-1 contributes the majority of activity measured in extracts of whole flies. Pyridoxal oxidase (PO) is also a broad range AO. It is prominent only in midgut and Malpighian tubules, where it apparently accounts for a substantial fraction of total AO activity. The tissue distributions of these enzymes are clearly disparate despite close linkage of their structural loci and parallel dependence on the mal, lxd, and cin loci. A similarly related enzyme, xanthine dehydrogenase (XDH), is detected as an AO only in electrophoretic gels. A fourth broad range AO, not dependent on mal, lxd, and cin, is confined to the ejaculatory bulb. A similar array of AO isozymes is present in phylogenetically distant Drosophila species.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00484627
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