 Hi everyone and thank you for joining in. My name is Christian and in this presentation I'll present the research that I'm doing during my IS fellowship at the August Institute of Advanced Studies. I'm an IS Co-Found Fellow and Assistant Professor at August Institute of Advanced Studies and here I'm researching in comparative animal physiology where I want to understand how animals function in the in the natural environments. And here I study a subgroup of animal physiology called respiration physiology with the goal of understanding how some animals can take up oxygen from the environment transported by the blood and release it to the tissues. And here I'm particularly interested in animals that have higher capacities to perform these physiological functions and try to understand the physiological and biochemical mechanisms that these animals utilize to better transport oxygen within their bodies. So the oxygen transport cascade is a multi step process where first oxygen is taking up into the bodies of animals either over the gills or over the lungs. It is transported by the blood to the respiring tissues and the final process or the final step in the oxygen transport cascade is the diffusion of oxygen from the red blood cell into the respiring tissues. And here oxygen is gradually depleted over distance so at the capillary wall the oxygen levels so the partial pressure of oxygen is very high. But when oxygen diffuses into the tissues, oxygen is gradually taking up into the cells and the oxygen levels are reduced eventually reaching zero so at a point where there's no oxygen left. And here the cells cannot function anymore because they don't have the sufficient amount of oxygen to generate energy to function. And for that reason, all the cells or all the tissues within our bodies have a very dense capillary network that allows for sufficient amount of oxygen diffusion into all the cells in our bodies so that they can function properly. This applies to almost all tissues but one particular tissue is special and that is the retina within our eyes. The retina is a neuronal tissue and the overall function of this tissue is to transform the light impulses that comes into the eye into a neuronal signal that can go into our brains and be interpreted as visual input. The retina has an inverted design and that means that light must transmit through all the different neuronal layers before reaching the light sensitive cells, the photoreceptors that line the back of the retina. And here you can imagine that any capillaries or blood vessels that are present in this part of the retina will scatter and scatter light and absorb the photons before the light reaches the photoreceptors and thereby reduce visual acuity. So for that reason, almost all vertebrate animals only have a network of capillaries in the back of the retina that allows for oxygen diffusion into the retina. But as you can imagine, oxygen is rapidly taken up so that reduces the the thickness of the retina that dictates visual performance. So if we look at the distribution of retinal thicknesses across different vertebrate species where each dot represents a different species, some of the visually poor performing animals such as blind cave fishes, particularly locating bats or electric fishes, they have very thin retinas and poor visual performance. And here our models for oxygen diffusion applies well because oxygen can easily diffuse from the from this capillary network into the whole retina. So if we look at some of the visually well performing animals such as hawks and eagles and and other birds and some fishes, they have a very, very thick retina that is over 600 micrometers thick, where oxygen can by no means diffuse over such long distances. And therefore these animals are interesting in terms of understanding physiological mechanisms to boost oxygen supply to neural tissues. So therefore I'm interested in understanding the physiological and biochemical mechanisms that allows these animals to boost their oxygen supply to neural tissues. These mechanisms may have supported the evolution of superior vision in birds and some of the other well visually performing animals. So to understand this I want to gain information about the physiological mechanisms that animals used to transport oxygen within the retina. I want to gain a molecular understanding of these physiological mechanisms, and I want to investigate this in a more comparative or evolutionary context. So there's kind of three different layers in my research. In the physiological studies I want to understand how oxygen diffuses within the retina. So here I can anesthetize birds and and other animals and insert a very thin glass electrode into the into the eye and gain information about the different oxygen levels that are that are found in different parts of the retina. And by fitting different mathematical models for oxygen diffusion to the data, then I can gain information about the physiological mechanisms underlying underlying gas diffusion. I also apply some molecular approaches to to understand the biochemical mechanisms underlying the physiological mechanisms for gas diffusion. Here use a technique called spatial transcriptomics where we can take a histological cryo section and put it on a gene expression slide where we can capture messenger RNA in the different parts of the retina. And here we can gain information about the transcriptomes in individual cell types within the body and also with relation to the to the oxygen levels that are found in the cell types. So we can map the expression of different genes on a retinal section, and we can also superimpose these oxygen levels that we obtained in the physiological approaches described before. And then we can go in and disentangle what are the effect of the of oxygen levels and cell types on the expression of different gene products. So this provides intricate information about how animals function in terms of supplying oxygen to their eyes. And here we gain very mechanistic insight into how animals function, but I don't just try to understand how individual animals function in isolation but also try to look at this in a more broader perspective. So here I study both birds but also their closely related reptile sister species. And by by knowing their phylogenetic relationship, so the tree of life that connects these different species. It is possible to track back in time how physiology and anatomy have looked in these internal branches so that represents prehistoric ancestors that connects these current living species. And by being able to mathematically backtrack how animals have functioned and looked, it is possible to reconstruct how anatomy, biochemistry and physiology have looked in internal branches of the tree of life, and reconstruct how physiological and soft tissue structures such as the I have evolved over time. This research provides physiological insight into the physiological basis for the evolution of sensory organs with a specific focus on vision. It provides insight into how prehistoric animals have functioned and looked, and it provides insight into how complex physiological systems have evolved over time, which has always been a test case in evolutionary biology. Furthermore, with more future applications, this research provides insight into naturally evolved mechanisms to boost oxygen supply to neural tissue, and this may have biochemical implications if we can translate some of these mechanisms into mammalian disease models. Thank you very much for joining in and feel free to contact me if you have any questions or comments.