Discovery of Sympathetic Neurons Originating from the Neural Crest in a Jawless Vertebrate, Challenging the Prevailing Belief about the Evolution of the Sympathetic Nervous System

แนวคิดหลัก

The presence of trunk sympathetic neurons in the sea lamprey, a jawless vertebrate, challenges the prevailing belief that sympathetic ganglia arose only in jawed vertebrates, suggesting that a rudimentary sympathetic nervous system may have been characteristic of the earliest vertebrates.

บทคัดย่อ

The study reports the discovery of trunk sympathetic neurons in the sea lamprey, Petromyzon marinus, an extant jawless vertebrate. These neurons arise from sympathoblasts near the dorsal aorta and undergo noradrenergic specification through a transcriptional program homologous to that described in jawed vertebrates (gnathostomes).

The lamprey sympathoblasts populate the extracardiac space and extend along the length of the trunk in bilateral streams, expressing the catecholamine biosynthetic pathway enzymes tyrosine hydroxylase and dopamine β-hydroxylase. Lineage tracing analysis confirmed that these cells derive from the trunk neural crest. RNA sequencing of the isolated ammocoete trunk sympathoblasts revealed gene profiles characteristic of sympathetic neuron function.

This finding challenges the prevailing dogma that sympathetic ganglia are a gnathostome (jawed vertebrate) innovation. Instead, it suggests that a late-developing rudimentary sympathetic nervous system may have been characteristic of the earliest vertebrates, predating the emergence of jaws.

สถิติ

The sea lamprey, Petromyzon marinus, is an extant jawless vertebrate.
Trunk sympathetic neurons in the sea lamprey express the catecholamine biosynthetic pathway enzymes tyrosine hydroxylase and dopamine β-hydroxylase.
Lineage tracing analysis confirmed that the lamprey sympathoblasts derive from the trunk neural crest.
RNA sequencing of the isolated ammocoete trunk sympathoblasts revealed gene profiles characteristic of sympathetic neuron function.

คำพูด

"Our findings challenge the prevailing dogma that posits that sympathetic ganglia are a gnathostome innovation, instead suggesting that a late-developing rudimentary sympathetic nervous system may have been characteristic of the earliest vertebrates."
"Although jawless vertebrates have sensory ganglia, convention has it that trunk sympathetic chain ganglia arose only in jawed vertebrates."

ข้อมูลเชิงลึกที่สำคัญจาก

Neural crest origin of sympathetic neurons at the dawn of vertebrates - Nature

by Brittany M. ... ที่ www.nature.com 04-17-2024

https://www.nature.com/articles/s41586-024-07297-0

สอบถามเพิ่มเติม

What other key evolutionary innovations may have been present in the earliest vertebrates, beyond the sympathetic nervous system, that are not currently recognized?

In addition to the sympathetic nervous system, other key evolutionary innovations that may have been present in the earliest vertebrates could include the development of specialized sensory organs, the emergence of complex neural circuits for motor control, the evolution of endocrine systems for hormonal regulation, and the establishment of adaptive immune responses. These innovations would have played crucial roles in the survival and diversification of early vertebrates, contributing to their ability to interact with the environment, respond to stimuli, and maintain internal homeostasis.

How might the presence of a rudimentary sympathetic nervous system in jawless vertebrates have influenced the subsequent evolution and diversification of vertebrates?

The presence of a rudimentary sympathetic nervous system in jawless vertebrates could have had significant implications for the subsequent evolution and diversification of vertebrates. This primitive sympathetic system likely provided early vertebrates with the ability to regulate physiological functions such as heart rate, blood pressure, and metabolism, thereby enhancing their capacity to respond to stress and environmental challenges. The development of sympathetic neurons in jawless vertebrates may have facilitated the evolution of more complex neural circuits and behaviors in later vertebrates, contributing to the emergence of sophisticated adaptive responses and increased physiological complexity. Additionally, the presence of sympathetic neurons in jawless vertebrates could have laid the foundation for the evolution of autonomic control systems that are essential for coordinating internal organ function and maintaining homeostasis in vertebrates.

What insights could further comparative studies of the neural crest and its derivatives across a broader range of extant vertebrate lineages provide about the origins and early evolution of the vertebrate nervous system?

Further comparative studies of the neural crest and its derivatives across a broader range of extant vertebrate lineages could offer valuable insights into the origins and early evolution of the vertebrate nervous system. By examining the developmental processes and genetic programs associated with neural crest cell migration, differentiation, and diversification in different vertebrate species, researchers can gain a deeper understanding of the evolutionary changes that have shaped the vertebrate nervous system over millions of years. Comparative studies may reveal conserved molecular pathways and regulatory mechanisms that govern neural crest development across vertebrates, highlighting key genetic factors that have been preserved throughout evolution. Additionally, by analyzing the diversity of neural crest-derived cell types and structures in various vertebrate lineages, researchers can elucidate the evolutionary transitions that have led to the complexity and specialization of the vertebrate nervous system, shedding light on the adaptive changes that have occurred in response to different ecological and physiological challenges. Overall, comparative studies of the neural crest in diverse vertebrates have the potential to uncover fundamental principles underlying the evolution of the nervous system and provide insights into the genetic and developmental mechanisms that have driven its evolutionary history.