Aim: What time should I hatch? This fascinating PhD project will investigate the crucial time in every bird’s life: the transition from imprisonment inside an egg shell, to life as a freely moving chick. The overarching questions are what neuroendocrine mechanisms regulate hatch and the stimulation of feeding behaviour? Do these mechanisms differ between precocial and altricial species? The outcomes will have significant implications for our basic understanding of avian early life.
Background: Most wild birds will coordinate and hatch in a clutch at the same time of day, but what environmental factors determines this? Is there an internal biological clock driving hatching? Previous studies have demonstrated that clock genes likely play a key role in organising the anticipation of environmental changes and that the circadian system matures toward the end of incubation (Okabayashi et al 2003). To gain a better understanding of how the circadian system matures during development the project will investigate pre- and postnatal central and peripheral oscillators though the quantification of clock gene expression through RNAseq and qPCR. Altricial (zebra finches) and precocial (quail) will be compared. The molecular machinery that generates circadian oscillations might mature at different rates in different tissues and may shift as the organ’s function changes during development.
For all vertebrates an internal circadian biological clock coordinates the expression of biological rhythms and enables anticipation of the changing environment. Under most conditions, light is the most important exogenous factor that entrains the circadian system and allows organisms to anticipate daily natural environmental changes. The light dark cycle could determine time of hatch and this project will determine the ontogeny of photoreception and the developmental expression of opsins in relation to hatch in precocial and altricial species.
There is evidence that other cues may also play a role in determining hatching e.g. temperature or sound. Are these other signals able to reset or entrain the developing circadian system to synchronise hatching? There will be scope to examine the impact of these other environmental factors on hatching and circadian clock gene expression. Food availability is also a key environmental signal and food (or feeding) can entrain some peripheral clocks (Vujovic et al., 2008). There will also be scope to quantify feeding behaviour and the neural feeding circuits by examining changes in gene expression post hatch.
Training: This project offers a wide range of training opportunities including experimental design, neurobiology, molecular biology, behaviour, bioinformatics, and statistical analysis of a range of types of data. The student will take the lead role in data collection, interpretation and drafting manuscripts for publication. The student will be encouraged to engage with other scientists in the respective institutes to foster their own collaborations and attend and present their findings at UK and international conferences.
Okabayashi N, Yasuo S, Watanabe M, Namikawa T, Ebihara S, Yoshimura T. (2003) Ontogeny of circadian clock gene expression in the pineal and the suprachiasmatic nucleus of chick embryo. Brain Res. 990(1-2):231-4.
Vujovic N, Davidson AJ, Menaker M. (2007) Sympathetic input modulates, but does not determine, phase of peripheral circadian oscillators. Am J Physiol Regul Integr Comp Physiol. 295(1):R355-60.
Mole DJ, Webster SP, Uings I, Zheng X, Binnie M, Wilson K, Hutchinson JP, Mirguet O, Walker A, Beaufils B, Ancellin N, Trottet L, Bénéton V, Mowat CG, Wilkinson M, Rowland P, Haslam C, McBride A, Homer NZ, Baily JE, Sharp MG, Garden OJ, Hughes J, Howie SE, Holmes DS, Liddle J, Iredale JP. (2016) Inhibition of kynurenine-3-monooxygenase activity protects against multiple organ failure in rodent models of severe acute pancreatitis. Nat Med, 22: 202-209.