Circatidal activity rhythm in the mangrove cricketApteronemobius asahinai

Abstract

Mangrove forests are influenced by tidal flooding and ebbing for a period of approximately 12.4 hours (tidal cycle). Mangrove crickets ( Apteronemobius asahinai ) forage on mangrove forest floors only during low tide. Under constant darkness, most crickets showed a clear bimodal daily pattern in their locomotor activity for at least 24 days; the active phases of approximately 10 hours alternated with inactive phases of approximately 2 hours, which coincided with the time of high tide in the field. The free-running period was 12.56±0.13 hours (mean±s.d., n =11). This endogenous rhythm was not entrained by the subsequent 24 hours light–dark cycle, although it was suppressed in the photophase; the active phase in the scotophase continued from the active phase in the previous constant darkness, with no phase shift. The endogenous rhythm was assumed to be a circatidal rhythm. On the other hand, the activity under constant darkness subsequent to a light–dark cycle was more intense in the active phase continuing from the scotophase than from the photophase of the preceding light–dark cycle; this indicates the presence of circadian components. These results suggest that two clock systems are involved in controlling locomotor activity in mangrove crickets.

Vertical Movements of a Mekong Giant Catfish (Pangasianodon gigas) in Mae Peum Reservoir, Northern Thailand, Monitored by a Multi-Sensor Micro Data Logger

“…4 and 5) exhibited no feeding cycle. Thus, the seasonal feeding/fasting cycle in this catfish may be controlled by an endogenous clock system, as seen in other organisms (Gwinner, 1996;Satoh et al, 2008).…”

“…Generally, organisms have various biological rhythms (e.g., circadian, circalunar, circatidal, and circannual rhythms) for reproduction, migration, and feeding (Baggerman, 1985;Boujard and Leatherland, 1992;Foote et al, 1992;Gwinner, 1986Gwinner, , 1996Heilman and Spieler, 1999;Mizushima et al, 2000;Satoh et al, 2008;Wikelski et al, 2009;Takemura et al, 2010). Seasonal feeding rhythms usually involve a fasting period; such a pattern has been identified in various organisms, especially in avian and mammalian species (Hissa, 1997;Piersma et al, 2008).…”

RNAi of the circadian clock geneperioddisrupts the circadian rhythm but not the circatidal rhythm in the mangrove cricket

“…Under constant darkness, adults of this species show a clear and persistent circatidal activity rhythm with a free-running period of approximately 12.6 h [9]. Moreover, a circadian rhythm modifying the circatidal rhythm by inhibiting activity during subjective day free-runs under constant darkness and can be entrained by light -dark cycles [9]. In insects, the molecular basis of the circadian clock has been extensively studied [10], and the predominant role of the gene period (per) is confirmed in some species, including a cricket, Gryllus bimaculatus [11].…”

“…Under constant darkness, adults of this species show a clear and persistent circatidal activity rhythm with a free-running period of approximately 12.6 h [9]. Moreover, a circadian rhythm modifying the circatidal rhythm by inhibiting activity during subjective day free-runs under constant darkness and can be entrained by light -dark cycles [9].…”

“…In A. asahinai, a circadian rhythm modifies activity levels in circatidal active phases [9]. When a circatidal rhythm was detected, the number of infrared beam interruptions was counted for every circatidal period shown by the chi-square periodogram.…”