Università di Firenze, Dipartimento di Biologia, Via Romana 17, 50125 Firenze, Italy.
Institute of Biological Environmental and Rural Sciences, Aberystwyth University, Penglais, Aberystwyth, SY23 3DA, UK.
Sci Rep. 2016 Oct 19;6:35575. doi: 10.1038/srep35575.
Animals that use astronomical cues to orientate must make continuous adjustment to account for temporal changes in azimuth caused by Earth's rotation. For example, the Monarch butterfly possesses a time-compensated sun compass dependent upon a circadian clock in the antennae. The amphipod Talitrus saltator possesses both a sun compass and a moon compass. We reasoned that the time-compensated compass mechanism that enables solar orientation of T. saltator is located in the antennae, as is the case for Monarch butterflies. We examined activity rhythms and orientation of sandhoppers with antennae surgically removed, or unilaterally occluded with black paint. Removing or painting the antennae did not affect daily activity rhythms or competence to orientate using the sun. However, when tested at night these animals were unable to orientate correctly to the moon. We subsequently measured circadian gene expression in the antennae and brain of T. saltator and show the clock genes period and cryptochrome 2 are rhythmically expressed in both tissues, reminiscent of other arthropods known to possess antennal clocks. Together, our behavioural and molecular data suggest that, T. saltator has anatomically discrete lunar and solar orientation apparatus; a sun compass, likely located in the brain and a moon compass in the antennae.
利用天文线索定位的动物必须不断调整以适应地球自转引起的方位时间变化。例如，帝王蝶具有依赖触角生物钟的时间补偿太阳罗盘。沙蚤既具有太阳罗盘又具有月亮罗盘。我们推断，使 T. saltator 能够进行太阳定位的时间补偿罗盘机制位于触角中，就像帝王蝶一样。我们检查了触角被手术切除或单侧用黑漆阻塞的沙蚤的活动节律和定向能力。切除或涂漆触角不会影响使用太阳进行日常活动节律或定向的能力。但是，当在夜间进行测试时，这些动物无法正确地根据月亮进行定向。随后，我们测量了 T. saltator 触角和大脑中的昼夜节律基因表达，并表明生物钟基因周期和隐色素 2 在这两种组织中都呈节律性表达，这与已知具有触角钟的其他节肢动物相似。总之，我们的行为和分子数据表明，T. saltator 具有解剖上离散的月亮和太阳定位器官；一个太阳罗盘，可能位于大脑中，一个月亮罗盘位于触角中。
