THE FAMILY TREE GETS FISHY: SEA MONSTER AND HUMANS SHARE A BRAIN CONNECTION
 |
| Sea Lamprey (Petromyzon marinus) |
Ever pondered the age-old question: 'Where did life originate from?' It's one of science's most intriguing mysteries, right up there with the classic dilemma, 'Which came first: the egg or the chicken?' While the latter may spark a chuckle, the former has kept researchers up on their toes for generations. The hypothesis, often taught in schools, suggests that life emerged from the vast depths of the sea. As years roll by and research advances, this theory gains traction, with scientists steadily narrowing down the possibilities through rigorous investigation and discovery.
A recent study led by Investigator Robb Krumlauf, Ph.D., from the Stowers Institute for Medical Research, offers a glimpse into how the brains of ancient animals evolved. The team unexpectedly uncovered that a crucial molecular cue is very broadly required during vertebrate hindbrain development. The hindbrain is responsible for various physiological functions including regulation of breathing, heart rate, digestion, and the maintenance of the sleep-wake cycle. The team also discovered that the hindbrain of both sea lampreys and humans are constructed using a similar molecular and genetic toolkit.
The sea lamprey (Petromyzon marinus) also dubbed as the ‘Vampire of the Great Lakes’ has a history dating back 500 years. With its sharp teeth and specialized suction cup for feeding, the ancient fish makes for a formidable predator. These cartilaginous, jawless vertebrae are notorious for their feeding habits, extracting bodily fluids from other marine fishes and often killing them. With a high reproduction rate and virtually no natural predators, the sea lamprey wreaks havoc on fish populations, particularly in its native habitat of Michigan.
Unlike most vertebrates with jaws, the sea lamprey lack jaws, making them invaluable research subjects, to unlock the secrets of how vertebrate traits evolved. Alice Bedois Ph.D., lead author of the study, highlights a key evolutionary split: “Around 500 million years ago, vertebrates diverged in jawless and jawed lineages.” Bedois and her team wanted to understand how the vertebrate brain evolved, and whether jawed creatures possess unique brain features compared to their jawless counterparts.
Building a brain isn't just about the blueprints (genes). It's also about the construction crew (signalling molecules) that sets the foundation and guides the process. Previous research from the Krumlauf Lab and the lab of Dr. Marianne Bronner at the California Institute of Technology revealed that sea lampreys share the same ‘brain architecture’ (Gene Regulatory Network) with jawed vertebrates, including humans. The new study has data suggesting that the evolutionary connection between jawless and jawed vertebrates runs deeper. The team identified a crucial signalling molecule playing a key part in orchestrating the sea lamprey's hindbrain formation.
Bedois and her team found that the same genes and cues are involved in sea lamprey hindbrain development. These findings suggest that this process is ancestral to all vertebrates.
The cue is called Retinoic acid (RA), commonly called vitamin A. The researchers knew that retinoic acid cues the gene circulatory to build the hindbrain in complex species. What they did not anticipate was uncovering the involvement of Retinoic acid in initiating sea lamprey core hindbrain development. Krumlauf commented that this study provided a few strong pieces of evidence to prove the close relationship between humans, the sea lamprey, and even rats.
This discovery, pinpointing the formation of the gene circuitry governing hindbrain development to around 500 million years ago, serves as a springboard for further exploration. Researchers are now driven to investigate even deeper into our evolutionary past, seeking the very first instance of this conserved brain-building process.
REFERENCES
- Stowers Institute for Medical Research. "An awkward family reunion: Sea monsters are our cousins." ScienceDaily. ScienceDaily, 21 February 2024. <www.sciencedaily.com/releases/2024/02/240221160425.htm>.
- Bedois AMH, Parker HJ, Price AJ, Morrison JA, Bronner ME, Krumlauf R. Sea lamprey enlightens the origin of the coupling of retinoic acid signaling to vertebrate hindbrain segmentation. Nat Commun. 2024;15(1):DOI: 10.1038/s41467-024-45911-x.
Comments
Post a Comment