Light in early life: understanding the mechanisms of embryonic photoreception to improve poultry welfare and production

本项目将采用最先进的技术，研究鸟蛋人工孵化过程中光照对胚胎发育、孵化能力和孵化后结果的积极影响。家禽生产是英国和全世界农业部门的重要组成部分。仅在英国，每个月就有超过9000万个卵子被用于孵化。孵化期间的环境条件对正常发育至关重要，并可能在孵化后产生持久的影响。孵化率和孵化同步是业界关注的两个主要领域，因为低孵化率和不同步孵化导致小鸡损失。减少孵化不同步，提高孵化率是提高动物福利和效率的重要手段。在商业环境中，鸡蛋在黑暗中孵育，但孵育期间的光照已成为提高孵化率和孵化同步的潜在手段。我们对光照在孵育期间的作用以及如何优化的理解仍然有限。我们最近的工作表明，视网膜外光感受器（非视蛋白）代表了一种广泛的、进化上古老的光探测和反应形式，可以很容易地调节这些发育效应。我们的数据表明，视网膜外光感受器的表达至少比视视蛋白的表达早几天开始，并在整个发育过程中表现出明显的变化。该项目有三个具体目标：1。确定视网膜外光感受器在发育过程中的解剖定位和个体发生，以确定孵育期间光传递的最佳波长和时间。2. 通过转录组学分析，确定孵育期间光照激活的神经和发育通路，重点确定与孵化同步性相关的通路。具体来说，我们将确定在光照和黑暗条件下孵育反应中表现出表达变化的基因。3. 利用基因编辑的视蛋白敲除鸡系，阐明是否通过额外的视网膜光感受器（VA视蛋白和黑视蛋白）介导光暴露在孵育期间的积极作用。确定视蛋白介导的光检测与内分泌系统（如甲状腺、褪黑激素和糖皮质激素系统）以及孵化率和孵化同步之间的联系。这些研究将为胚胎能够探测和响应光线线索的机制提供独特的见解。这一认识不仅将为商业鸡蛋孵化提供信息，还将为更详细地了解夜间光照如何影响野生鸟类种群提供信息。这个及时的项目与BBSRC的战略重点相关：管理动物的福利，动物健康，可持续提高农业生产，整个生命过程中的健康老龄化和生物科学技术开发，以及罗斯林研究所的BBSRC资助的研究所战略计划：改善动物生产和福利。该项目汇集了一个强大的多学科团队，他们在禽类生理学、新型禽类基因靶向和突变生殖细胞的种系传播方面具有卓越的技能，以产生一个基因编辑的系，可以用作转移基因编辑的原始生殖细胞的无菌宿主（由于缺乏原始生殖细胞）。这项技术将导致高效生产携带所需视蛋白突变的鸟类。

This project will use state of the art technology to investigate the mechanism by which light exposure during artificial incubation of bird eggs exerts positive effects on embryonic development, hatchability and post-hatch outcomes. Poultry production is a major component of the agricultural sector in the UK and worldwide. Over 90 million eggs are set for incubation each month in the UK alone. Environmental conditions during incubation are vital for proper development and can have long lasting consequences post-hatch. Hatchability and hatch synchrony are two areas of major industry concern, as low hatchability and asynchronous hatch result in chick loss. Reduction of hatch asynchrony and improvement of hatchability represents a key means to improve animal welfare and efficiency. In commercial settings eggs are incubated in darkness but light exposure during incubation has emerged as a potential means of improving hatchability and hatch synchrony. Our understanding of how light exposure acts during incubation, and how it can be optimized remains limited. Our recent work has shown that extra-retinal photoreceptors (non-visual opsins) represent a widespread and evolutionarily ancient form of light detection and response that could readily mediate these developmental effects. Our data has shown that extra-retinal photoreceptor expression begins at least several days before that of visual opsin expression and displays marked changes across the developmental time course. The project has 3 specific objectives: 1. Determine the anatomical localization and ontogeny of extra-retinal photoreceptors across development to establish the optimal wavelengths and timing of light delivery during incubation. 2. By using transcriptomic analysis, identify the neural and developmental pathways activated by light exposure during incubation focusing on identification of pathways related to hatch synchronicity. Specifically we will identify genes that show changes in expression in response to incubation under light versus dark conditions. 3. Elucidate if light detection by the extra retinal photoreceptors (VA opsin and melanopsin) mediate the positive effects of light exposure during incubation using gene edited opsin knockout chicken lines. Identify linkages between opsin mediated light detection and the endocrine system e.g. thyroid, melatonin and glucocorticoid systems as well as hatchability and synchrony of hatch.These studies will provide unique insights into the mechanisms by which embryos are able to detect and respond to light cues. This understanding will inform not only commercial egg incubation, but inform a more detailed appreciation of how nocturnal light exposure may impact wild bird populations.This timely project is relevant to the BBSRC strategic priorities: Welfare of Managed Animals, Animal Health, Sustainably Enhancing Agricultural Production, Healthy Ageing Across the Life Course and Technology Development for the Biosciences and the Roslin Institute's BBSRC funded Institute Strategic Program: Improving Animal Production and Welfare. This project brings together a strong multidisciplinary team with exceptional skills in avian physiology as well as novel avian gene targeting and germ line transmission of mutated germ cells to generate a gene-edited line that can be used as a sterile host (due to absence of primordial germ cells) for transferred gene edited primordial germ cells. This technology will lead to highly efficient production of birds carrying the desired opsin mutation.