Nanda-Hamner experiment (Drosophilidae)

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Method synopsis

Experimental protocol to test for circadian rhythmicity in photoperiodic responses by exposing insects to constant day length (12h) with varying night lengths to create non-24h photoperiods, then measuring diapause induction rates.

Synthesized from method descriptions across 1 paper using this protocol.

Procedure from a recent peer-reviewed implementation

Steps below were extracted from the most recent peer-reviewed implementation of this protocol in the corpus — Nanda-Hamner Curves Show Huge Latitudinal Variation but No Circadian Components in <i> Drosophila Montana </i> Photoperiodism (2021), Journal of Biological Rhythms. Implementations in other papers (listed below) may differ.

1. Photoperiodic response curve experiments
   Female diapause proportions were measured in circadian and non-circadian photoperiods comprising 12h light + 4 to 72h darkness (total photoperiod 16 to 84h) and total darkness (DD) in NH experiments. Additionally, several 24h photoperiods between LD 8:16 and LD 24:0 were used for CDL estimation.
   Quantities: 6 LD cycles for NH experiment (LD 12:24, LD 12:36), multiple 24h photoperiods for CDL estimationDuration: Duration of experimental photoperiods not specifiedConditions: 16°C ± 0.3°C, light intensity 300-1000 lux
   Equipment: temperature-controlled chambers, white fluorescent lamps (9 W, Megaman, Germany)
2. Female diapause assessment
   Females were introduced into experimental photoperiods as pupae in malt media bottles. Emerging females and males were maintained together until females reached sexual maturity or entered reproductive diapause. Reproductive state was determined at age 21 ± 1 days by dissecting ovaries under a light microscope. Females were considered diapausing if ovaries were small and transparent and/or if they contained only a little yolk, or sexually mature if ovaries contained fully developed eggs.
   Quantities: Sample sizes given in Supplementary Tables S2 and S3, about 105,000 dissected females totalDuration: 21 ± 1 days from emergence to dissectionConditions: Maintained in experimental photoperiods from pupal stage
   Equipment: light microscope, dissection tools, malt media bottles

Typical Equipment

• temperature-controlled chambers
• white fluorescent lamps
• light microscope

Output Measurements

• female diapause proportions
• photoperiodic response curves

Papers Using This Protocol (1)

Species Studied With This Protocol

Places Where Used