The photoperiodic clock in the blowfly Calliphora vicina

Nunes, Marlies Vaz; Kenny, N. A. P.; Saunders, D. S.

doi:10.1016/0022-1910(90)90151-5

Cited by 36 publications

(16 citation statements)

References 23 publications

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“…Although its value could not be calculated at 26°C, at 24°C it appeared to be approximately 10.5 hr. This accords well with a previously published value for C. vicina at 23.5°C of 10.75 hr (Vaz Nunes et al, 1990). FIGURE 6.…”

Section: Diapause Induction Photoperiodic Response Curvessupporting

confidence: 93%

“…This objection is overcome by external-coincidence models incorporating either a single damping oscillation as the clock (Lewis and Saunders, 1987;Saunders and Lewis, 1987a,b), or a hierarchical pacemaker-slave device with a damping &dquo;photoperiodic&dquo; slave (Vaz Nunes et al, 1991a,b). Details of these models are not required here, but experimental evidence that is consistent with such damping in photoperiodism has been described for C. vicina by Vaz Nunes et al (1990).…”

Section: Discussionmentioning

confidence: 56%

“…Experiments based on the Nanda-Hamner (Nanda and Hamner, 1958) and bistability (Pittendrigh and Minis, 1971 ) protocols have indicated that the time-measuring system in C. vicina may be circadian in nature (Saunders et al, 1988;Vaz Nunes et al, 1990). Unfortunately, the inevitably indirect nature of these experiments, in which the only 1.…”

mentioning

confidence: 98%

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Adult Locomotor Rhythmicity as "Hands" of the Maternal Photoperiodic Clock Regulating Larval Diapause in the Blowfly, Calliphora vicina

Kenny

Saunders

1991

J Biol Rhythms

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Some basic properties of the adult locomotor activity rhythm and of the maternal induction of larval diapause in Calliphora vicina are described. Diapause responses in Nanda-Hamner experiments indicate that circadian rhythmicity is involved in photoperiodic time measurement (PPTM). However, although the locomotor rhythm shows long-lasting changes in free-running period (aftereffects of photoperiod and constant light) and occasional "splitting," thereby indicating a structural complexity to the circadian system, the overt rhythm may be used as an indicator of phase relationships (or "hands") of the covert system involved in PPTM, within the framework of a simple external-coincidence model for the diapause clock. Thus, in light-dark (LD) cycles close to "resonance" with the circadian pacemaker(s) (T 24, LD 12:12; T 48, LD 12:36; and T 72, LD 12:60), light is restricted to the subjective day and diapause incidence is high. In T 36 (LD 12:24) and T 60 (LD 12:48), light falls into the subjective night and illuminates the postulated light-sensitive phase (phi i), and diapause incidence is low. Within the primary range of entrainment, light invades the late subjective night in T 20 (LD 12:8), illuminates phi i, and causes low incidence of diapause; however, it invades the early subjective night in T 30 (LD 12:18) and diapause remains high.

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Section: Diapause Induction Photoperiodic Response Curvessupporting

confidence: 93%

Section: Discussionmentioning

confidence: 56%

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Adult Locomotor Rhythmicity as "Hands" of the Maternal Photoperiodic Clock Regulating Larval Diapause in the Blowfly, Calliphora vicina

Kenny

Saunders

1991

J Biol Rhythms

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“…These results were accounted for using the damped circadian oscillator model, with moderately damping circadian clocks. For the blowfly, C. vicina, a damping circadian clock also had been suggested from other experiments by Vaz Nunes et al (1990a) in which it was found that DD had the same inductive value as about 5 long-night (LD 8:16) cycles. Vaz Nunes and Hardie (1993) demonstrated with this protocol that the photoperiodic clock in the aphid, M. viciae, is based on a self-sustained or slightly damped circadian oscillator instead of an hourglass as was generally accepted (Lees, 1973;Saunders, 1982b); in this species, n cycles of LD 12:60 or LD 12:36 resulted in the same incidence of ovipara producers as did 3n or 2n cycles of LD 12:12, respectively.…”

Section: Experimental Tests Of Clock Models and Their Use In Guiding mentioning

confidence: 60%

Photoperiodic Time Measurement in Insects: A Review of Clock Models

Nunes¹,

Saunders²

1999

J Biol Rhythms

Self Cite

119

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Based on analyses of responses of insects and mites to a wide range of diel and nondiel experimental light-dark schedules, a variety of models have been developed for the photoperiodic clocks in these species by nearly as many investigators. According to some of these models, the photoperiodic clock is based on a mechanism separate from the circadian system, that is, a so-called "hourglass." According to other models, the clock is based on one or more circadian oscillators that may be coupled to each other and that may or may not show a certain degree of damping. In this context, a rapidly damping oscillator could be regarded as an hourglass. The present article gives an overview of the many different clock models and their philosophies, and it makes comparisons among them to provide a better understanding about how these models are related, if at all, and why the double circadian oscillator model is the most favored model at present.

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“…1) is about 22.5 h (Cymborowski et al, 1993) whereas that for photoperiodic induction, as judged from the inter-peak intervals in NandaHamner experiments (Fig. 5), is closer to 24 h. In the former, the rhythm persists undamped for several weeks, whereas for the latter there is evidence suggesting a rather heavily damping oscillator (Vaz Nunes et al, 1990). For D. melanogaster the evidence for the separate nature of overt rhythmicity and photoperiodic timing is more compelling, since the critical day lengths for the period mutants (per s and per L2) are the same as that for wild type (Saunders, 1990), and flies carrying per ~ or those devoid of the per gene (per') are apparently still capable of distinguishing short days from long days, although with a shortened critical day length (Fig.…”

Section: The Circadian Basis Of Photoperiodic Time Measurementmentioning

confidence: 88%

Insect circadian rhythms and photoperiodism

Saunders

1997

Invertebrate Neuroscience

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Two clock-controlled processes, overt circadian rhythmicity and the photoperiodic induction of diapause, are described in the blow fly, Calliphora vicina and the fruit fly, Drosophila melanogaster. Circadian locomotor rhythms of the adult flies reflect endogenous, self-sustained oscillations with a temperature compensated period. The free-running rhythms become synchronised (entrained) to daily light:dark cycles, but become arrhythmic in constant light above a certain intensity. Some flies show fragmented rhythms (internal desynchronisation) suggesting that overt rhythmicity is the product of a multioscillator (multicellular) system. Photoperiodic induction of larval diapause in C. vicina and of ovarian diapause in D. melanogaster is also based on the circadian system but seems to involve a separate mechanism at both the molecular and neuronal levels. For both processes in both species, the compound eyes and ocelli are neither essential nor necessary for photic entrainment, and the circadian clock mechanism is not within the optic lobes. The central brain is the most likely site for both rhythm generation and extra-optic photoreception. In D. melanogaster, a group of lateral brain neurons has been identified as important circadian pacemaker cells, which are possibly also photo-sensitive. Similar lateral brain neurons, staining for arrestin, a protein in the phototransduction 'cascade' and a selective marker for photoreceptors in both vertebrates and invertebrates, have been identified in C. vicina. Much less is known about the cellular substrate of the photoperiodic mechanism, but this may involve the pars intercerebralis region of the mid-brain.

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The photoperiodic clock in the blowfly Calliphora vicina

Cited by 36 publications

References 23 publications

Adult Locomotor Rhythmicity as "Hands" of the Maternal Photoperiodic Clock Regulating Larval Diapause in the Blowfly, Calliphora vicina

Adult Locomotor Rhythmicity as "Hands" of the Maternal Photoperiodic Clock Regulating Larval Diapause in the Blowfly, Calliphora vicina

Photoperiodic Time Measurement in Insects: A Review of Clock Models

Insect circadian rhythms and photoperiodism

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