Mar 18, 2022 07:10 PM
(This post was last modified: Mar 18, 2022 07:35 PM by C C.)
Before brains, biomechanics may have ruled animal behavior
https://www.quantamagazine.org/before-br...-20220316/
Biomechanical interactions, rather than neurons, control the movements of one of the simplest animals. The discovery offers a glimpse into how animal behavior worked before neurons evolved.
INTRO: The biophysicist Manu Prakash vividly remembers the moment, late one night in a colleague’s laboratory a dozen years ago, when he peered into a microscope and met his new obsession. The animal beneath the lenses wasn’t much to look at, resembling an amoeba more than anything else: a flattened multicellular blob, only 20 microns thick and a few millimeters across, with neither head nor tail. It moved on thousands of cilia that blanketed its underside to form the “sticky hairy plate” that inspired its Latin name, Trichoplax adhaerens.
This odd marine creature, classified as a placozoan, has practically an entire branch on the evolutionary tree of life to itself, as well as the smallest known genome in the animal kingdom. But what intrigued Prakash most was the well-orchestrated grace, agility and efficiency with which the thousands to millions of cells in Trichoplax moved.
After all, such coordination usually requires neurons and muscles — and Trichoplax has neither.
Prakash later teamed up with Matthew Storm Bull, then his graduate student at Stanford University, to make this strange organism the star of an ambitious project aimed at understanding how neuromuscular systems might have evolved — and how early multicellular creatures managed to move, find food and reproduce before neurons existed.
“I often jokingly call this neuroscience without neurons,” Prakash said.
In a trio of preprints totaling more than 100 pages — posted simultaneously on the arxiv.org server last year — he and Bull showed that the behavior of Trichoplax could be described entirely in the language of physics and dynamical systems. Mechanical interactions that began at the level of a single cilium, and then multiplied over millions of cells and extended to higher levels of structure, fully explained the coordinated locomotion of the entire animal. The organism doesn’t “choose” what to do. Instead, the horde of individual cilia simply moves — and the animal as a whole performs as though it is being directed by a nervous system. The researchers even showed that the cilia’s dynamics exhibit properties that are commonly seen as distinctive hallmarks of neurons.
The work not only demonstrates how simple mechanical interactions can generate incredible complexity, but also tells a compelling story about what might have predated the evolution of the nervous system.
“It’s a tour de force of biophysics,” said Orit Peleg of the University of Colorado, Boulder, who was not involved in the studies. The findings have already started to inspire the design of mechanical machines and robots, and perhaps even a new way of thinking about the role of nervous systems in animal behavior... (MORE - missing details)
New insight into the possible origins of life
https://www.u-tokyo.ac.jp/focus/en/press...00210.html
RELEASE: Researchers at the University of Tokyo have for the first time been able to create an RNA molecule that replicates, diversifies and develops complexity, following Darwinian evolution. This has provided the first empirical evidence that simple biological molecules can lead to the emergence of complex lifelike systems.
Life has many big questions, not least being where did we come from? Maybe you've seen the T-shirts with pictures going from ape to human (to tired office worker). But how about from simple molecule to complex cell to ape?
For several decades, one hypothesis has been that RNA molecules (which are vital for cell functions) existed on primitive Earth, possibly with proteins and other biological molecules. Then around 4 billion years ago, they started to self-replicate and develop from a simple single molecule into diverse complex molecules. This step-by-step change possibly eventually led to the emergence of life as we know it -- a beautiful array of animals, plants, and everything in between.
Although there have been many discussions about this theory, it has been difficult to physically create such RNA replication systems. However, in a study published in Nature Communications, Project Assistant Professor Ryo Mizuuchi and Professor Norikazu Ichihashi at the Graduate School of Arts and Sciences at the University of Tokyo, and their team, explain how they carried out a long-term RNA replication experiment in which they witnessed the transition from a chemical system towards biological complexity.
The team was truly excited by what it saw. "We found that the single RNA species evolved into a complex replication system: a replicator network comprising five types of RNAs with diverse interactions, supporting the plausibility of a long-envisioned evolutionary transition scenario," said Mizuuchi.
Compared to previous empirical studies, this new result is novel because the team used a unique RNA replication system that can undergo Darwinian evolution, i.e., a self-perpetuating process of continuous change based on mutations and natural selection, which enabled different characteristics to emerge, and the ones that were adapted to the environment to survive.
"Honestly, we initially doubted that such diverse RNAs could evolve and coexist," commented Mizuuchi. "In evolutionary biology, the 'competitive exclusion principle' states that more than one species cannot coexist if they are competing for the same resources. This means that the molecules must establish a way to use different resources one after another for sustained diversification. They are just molecules, so we wondered if it were possible for nonliving chemical species to spontaneously develop such innovation."
So what next? According to Mizuuchi, "The simplicity of our molecular replication system, compared with biological organisms, allows us to examine evolutionary phenomena with unprecedented resolution. The evolution of complexity seen in our experiment is just the beginning. Many more events should occur towards the emergence of living systems."
Of course, there are still many questions left to answer, but this research has provided further empirically based insight into a possible evolutionary route that an early RNA replicator may have taken on primitive Earth. As Mizuuchi said, "The results could be a clue to solving the ultimate question that human beings have been asking for thousands of years -- what are the origins of life?"
https://www.quantamagazine.org/before-br...-20220316/
Biomechanical interactions, rather than neurons, control the movements of one of the simplest animals. The discovery offers a glimpse into how animal behavior worked before neurons evolved.
INTRO: The biophysicist Manu Prakash vividly remembers the moment, late one night in a colleague’s laboratory a dozen years ago, when he peered into a microscope and met his new obsession. The animal beneath the lenses wasn’t much to look at, resembling an amoeba more than anything else: a flattened multicellular blob, only 20 microns thick and a few millimeters across, with neither head nor tail. It moved on thousands of cilia that blanketed its underside to form the “sticky hairy plate” that inspired its Latin name, Trichoplax adhaerens.
This odd marine creature, classified as a placozoan, has practically an entire branch on the evolutionary tree of life to itself, as well as the smallest known genome in the animal kingdom. But what intrigued Prakash most was the well-orchestrated grace, agility and efficiency with which the thousands to millions of cells in Trichoplax moved.
After all, such coordination usually requires neurons and muscles — and Trichoplax has neither.
Prakash later teamed up with Matthew Storm Bull, then his graduate student at Stanford University, to make this strange organism the star of an ambitious project aimed at understanding how neuromuscular systems might have evolved — and how early multicellular creatures managed to move, find food and reproduce before neurons existed.
“I often jokingly call this neuroscience without neurons,” Prakash said.
In a trio of preprints totaling more than 100 pages — posted simultaneously on the arxiv.org server last year — he and Bull showed that the behavior of Trichoplax could be described entirely in the language of physics and dynamical systems. Mechanical interactions that began at the level of a single cilium, and then multiplied over millions of cells and extended to higher levels of structure, fully explained the coordinated locomotion of the entire animal. The organism doesn’t “choose” what to do. Instead, the horde of individual cilia simply moves — and the animal as a whole performs as though it is being directed by a nervous system. The researchers even showed that the cilia’s dynamics exhibit properties that are commonly seen as distinctive hallmarks of neurons.
The work not only demonstrates how simple mechanical interactions can generate incredible complexity, but also tells a compelling story about what might have predated the evolution of the nervous system.
“It’s a tour de force of biophysics,” said Orit Peleg of the University of Colorado, Boulder, who was not involved in the studies. The findings have already started to inspire the design of mechanical machines and robots, and perhaps even a new way of thinking about the role of nervous systems in animal behavior... (MORE - missing details)
New insight into the possible origins of life
https://www.u-tokyo.ac.jp/focus/en/press...00210.html
RELEASE: Researchers at the University of Tokyo have for the first time been able to create an RNA molecule that replicates, diversifies and develops complexity, following Darwinian evolution. This has provided the first empirical evidence that simple biological molecules can lead to the emergence of complex lifelike systems.
Life has many big questions, not least being where did we come from? Maybe you've seen the T-shirts with pictures going from ape to human (to tired office worker). But how about from simple molecule to complex cell to ape?
For several decades, one hypothesis has been that RNA molecules (which are vital for cell functions) existed on primitive Earth, possibly with proteins and other biological molecules. Then around 4 billion years ago, they started to self-replicate and develop from a simple single molecule into diverse complex molecules. This step-by-step change possibly eventually led to the emergence of life as we know it -- a beautiful array of animals, plants, and everything in between.
Although there have been many discussions about this theory, it has been difficult to physically create such RNA replication systems. However, in a study published in Nature Communications, Project Assistant Professor Ryo Mizuuchi and Professor Norikazu Ichihashi at the Graduate School of Arts and Sciences at the University of Tokyo, and their team, explain how they carried out a long-term RNA replication experiment in which they witnessed the transition from a chemical system towards biological complexity.
The team was truly excited by what it saw. "We found that the single RNA species evolved into a complex replication system: a replicator network comprising five types of RNAs with diverse interactions, supporting the plausibility of a long-envisioned evolutionary transition scenario," said Mizuuchi.
Compared to previous empirical studies, this new result is novel because the team used a unique RNA replication system that can undergo Darwinian evolution, i.e., a self-perpetuating process of continuous change based on mutations and natural selection, which enabled different characteristics to emerge, and the ones that were adapted to the environment to survive.
"Honestly, we initially doubted that such diverse RNAs could evolve and coexist," commented Mizuuchi. "In evolutionary biology, the 'competitive exclusion principle' states that more than one species cannot coexist if they are competing for the same resources. This means that the molecules must establish a way to use different resources one after another for sustained diversification. They are just molecules, so we wondered if it were possible for nonliving chemical species to spontaneously develop such innovation."
So what next? According to Mizuuchi, "The simplicity of our molecular replication system, compared with biological organisms, allows us to examine evolutionary phenomena with unprecedented resolution. The evolution of complexity seen in our experiment is just the beginning. Many more events should occur towards the emergence of living systems."
Of course, there are still many questions left to answer, but this research has provided further empirically based insight into a possible evolutionary route that an early RNA replicator may have taken on primitive Earth. As Mizuuchi said, "The results could be a clue to solving the ultimate question that human beings have been asking for thousands of years -- what are the origins of life?"
