Periodic Reporting for period 3 - ParadOX (The hardships for life to become big – rethinking hypoxia as an evolutionary driver for the rise of complex multicellularity)
Okres sprawozdawczy: 2024-01-01 do 2025-06-30
Why complex life evolved on Earth has puzzled scientists for as long as sufficient oxygen has been deemed vital. The problem is that our current explanations have not yet been able to explain the observations. Motivated by recent discoveries, however, this project will investigate the dawning paradox that multicellular life requires low oxygen (hypoxia) internally to thrive in the oxic niche. Central biological mechanisms in animals and plants need protection from oxygen and appears to depend on hypoxic niches. To harness hypoxia may have been essential for animals to maintain cell stemness and thus conquer the previously inaccessible oxic niche. Although life must have invented several solutions to the paradox that tissue renewal requires cell stemness that appear to be facilitated by low-oxygen conditions, the only known is the cell mechanism for cells sense oxygen (HIF-a). Earth history can uniquely evaluate its evolutionary importance through a geologic lens. Insights to the evolutionary importance and processes that underpin biological innovations to harness hypoxia will advance our view on the rise of multicellularity on Earth, on other planets, and even within us as “tumor multicellularity”.
In the ParadOX project, I and a transdisciplinary team explore the role of innovations that harness hypoxia and the processes that led to these innovations. The overall objective is to explore the role of hypoxia for the evolution of multicellularity and to what extent oxygen-sensing mechanisms play a part.
In the ParadOX project, I and a transdisciplinary team explore the role of innovations that harness hypoxia and the processes that led to these innovations. The overall objective is to explore the role of hypoxia for the evolution of multicellularity and to what extent oxygen-sensing mechanisms play a part.
From the beginning and 30 months into the project, the work has entailed for example:
• A comparison how aspects of their oxygen-sensing mechanisms are shared between animals, fungi, and plants. Their mechanisms are functionally convergent.
• Modeling of how daily oxygen fluctuations would affect living conditions at the sediment-water interface on an expanding shallow shelf setting in the Cambrian Period and affect animals with poor versus good oxygen-sensing mechanisms. The work demonstrates that animals on the shallow Cambrian shelf would have been challenged by daily shifts from oxic (in the day) to anoxic (at night), even when testing over a broad parameter space.
• We have also showed that chick embryo development requires an initial phase of hypoxia within the eggshell. It is the exponential growth of the embryo earliest stages that overpowers the influx of oxygen through the eggshell.
• We have geochemically analyzed a drillcore from the Silurian and interpret that for most part of the 15 million years that it spans. We here also discuss how the term hypoxia have different meanings in different academic disciplines.
• A comparison how aspects of their oxygen-sensing mechanisms are shared between animals, fungi, and plants. Their mechanisms are functionally convergent.
• Modeling of how daily oxygen fluctuations would affect living conditions at the sediment-water interface on an expanding shallow shelf setting in the Cambrian Period and affect animals with poor versus good oxygen-sensing mechanisms. The work demonstrates that animals on the shallow Cambrian shelf would have been challenged by daily shifts from oxic (in the day) to anoxic (at night), even when testing over a broad parameter space.
• We have also showed that chick embryo development requires an initial phase of hypoxia within the eggshell. It is the exponential growth of the embryo earliest stages that overpowers the influx of oxygen through the eggshell.
• We have geochemically analyzed a drillcore from the Silurian and interpret that for most part of the 15 million years that it spans. We here also discuss how the term hypoxia have different meanings in different academic disciplines.
If accepted by our peers, it would be progress beyond the state of the art to demonstrate how the Cambrian explosion was the result of increased physiological stress. There is also great progress by demonstrating that even early development of a vertebrate (chick embryo) require a phase of environmental hypoxia.