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1982 (2)
1980 (1)
1Author    Wilhelmine Erckens, Wolfgang MartinRequires cookie*
 Title    Exogenous and Endogenous Control of Swimming Activity in Astyanax mexicanus (Characidae, Pisces) by Direct Light Response and by a Circadian Oscillator I. Analyses of the Time-Control Systems of an Epigean River Population  
 Abstract    1. The swimming activity of 6 specimens of an Astyanax mexicanus' river population was tested with regard to its time control under various light-dark(LD)cycles and under constant conditions. 2. Activity is classified into three different forms according to the special experimental arrange­ ment: surface activity, bottom activity and the sum of both (total activity). 3. All applied LD-cycles act as socalled forcing signals (Zeitgeber) and entrain the activity. 4. The maximum values of surface activity correspond to the dark phases of a LD-cycle, those of bottom activity to the light phases. This inversity causes a less strong entrainment of the total activity up to a loss of a significant oscillation in extreme cases. 5. This inverse pattern is kept the more stronger the more the period length of a LD deviates from 24 h. In the range of resonance about 24 h there is a greater flexibility with regard to the phase relation of the maximum values. 6. Activity reacts very sensitive to the differential parameter of the forcing signal. Therefore, no phaseangle difference occurs between forcing and forced signal. Moreover, the system needs no swing-in time to become entrained when starting a LD. 7. After transition from LD to D D (= constant darkness) the forced signal does not die away immediately, but damps out within one or a few cycles with decreasing amplitude and unchanged frequency. 8. In nearly all applied LDs a non-synchronized circadian rhythm can be observed in addition to the entrained frequency, which is dominant. 9. Also, in D D a freerunning circadian rhythm is detectable. 10. We suggest the model that first a passive system with a nearly unlimited range of entrain­ ment controls activity. In contrary to extremely passive systems, it is able to oscillate. Moreover, it acts like a linear system with respect to frequency transfer: In the tested cases, output and input frequency are equal. In addition, activity is under control of an endogenous circadian oscillator. Its effects are overlapped under forcing conditions, but they become obvious under constant con­ ditions. Furthermore, nonstationary processes are features of this circadian rhythm. The proper­ ties of a passive and a circadian system alone do not explain the flexible patterns in the range of resonance. Therefore, a time-dependent controller is demanded to control the phase relation of the maxima. 
  Reference    Z. Naturforsch. 37c, 1253—1265 (1982); received August 16 1982 
  Published    1982 
  Keywords    Astyanax, Epigean Ancestor, Circadian, Swimming Activity, Light Response 
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 TEI-XML for    default:Reihe_C/37/ZNC-1982-37c-1253.pdf 
 Identifier    ZNC-1982-37c-1253 
 Volume    37 
2Author    Wilhelmine Erckens, Wolfgang MartinRequires cookie*
 Title    Exogenous and Endogenous Control of Swimming Activity in Astyanax mexicanus (Characidae, Pisces) by Direct Light Response and by a Circadian Oscillator D. Features of Time-Controlled Behaviour of a Cave Population and their Comparison to a Epigean Ancestral Form  
 Abstract    1. The swimming activity of 6 specimens of the Pachon cave form of Astyanax mexicanus was tested with regard to its time control under various light-dark(LD)cycles and constant conditions, and it is compared to that of a river form. 2. In general, activity is entrainable by all applied LDs, but even if the amplitude of a forcing signal increases the signal energies are lower than in the river fish. 3. In case of entrainment the maximum values of surface activity correspond to the dark phases, those of bottom activity to the light phases of a LD. Flexible patterns -as often observed in the river form in the range of resonance about 24 h — are very seldom. Furthermore, disturbances of­ ten occur in the entrainment of one activity form, or one form runs arrhythmic while the other is still entrained. 4. The activity answers to changing environmental conditions are not as uniformly quick as in the river fish. But the system hardly needs a swing-in time to become entrained when a L D starts. 5. After transition from LD to D D (= constant darkness) the entrained rhythms disappear im ­ mediately. 6. In no LD with a period length differing from 24 h a circadian rhythm can be observed in ad­ dition to the entrained frequency. 7. These results show that the passive system of the river form has developped into an extremely passive one being unable to oscillate and thus has become simplified during regressive evolution. Concerning the circadian oscillator of the epigean ancestor, it was also subjected to regression, but it has not been completely lost. After a LD with a period length about 24 h the circadian oscillator is able to act as a stable system, clearly shown by the freerunning circadian rhythms of surface activity. But out of this range the oscillator is unable to control activity. In D D after all other LDs activity patterns are arrhythmic. 
  Reference    Z. Naturforsch. 37c, 1266—1273 (1982); received August 16 1982 
  Published    1982 
  Keywords    Astyanax, Cave Fish, Regressive Evolution, Circadian, Light Response 
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 TEI-XML for    default:Reihe_C/37/ZNC-1982-37c-1266.pdf 
 Identifier    ZNC-1982-37c-1266 
 Volume    37 
3Author    G. Ottfried, W. Iedenm, Ann, WolfgangM. ArtinRequires cookie*
 Title    Running Activity Patterns of Females and Last Larval Instars of the Cockroach Leucophaea maderae  
 Abstract    Virgin females of Leucophaea maderae reveal a circadian rhythm in their locomotor activity which is superimposed by the ovarial cycle. Locomotor activity of last larval instars does not exhibit a circadian pattern. 
  Reference    Z. Naturforsch. 35c, 816—818 (1980); received June 161980 
  Published    1980 
  Keywords    Circadian, Leucophaea, Ovarial Cycle, Running Activity, Time Series Analysis 
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 TEI-XML for    default:Reihe_C/35/ZNC-1980-35c-0816.pdf 
 Identifier    ZNC-1980-35c-0816 
 Volume    35