A global scientific collaboration, led by University of Malaga researcher Juan Pascual Anaya, has successfully sequenced the genome of myxini, commonly known as hagfish. This achievement is particularly noteworthy as myxini represents the only major vertebrate group without a reference genome. The groundbreaking findings, detailed in the journal Nature Ecology & Evolution, have significant implications for understanding the evolutionary history of genome duplications in vertebrates, including humans.
The research, spanning nearly a decade, involved over 40 authors from seven countries and more than 30 institutions, including the University of Tokyo, RIKEN in Japan, the Chinese Academy of Science, and the Centre for Genomic Regulation in Barcelona. The myxini, residing in deep ocean areas, are known for their mucosal release under threat, a subject of interest for cosmetic companies. They also play a crucial ecological role in the seabed by scavenging and decomposing whale carcasses.
Myxini genomes, characterized by numerous microchromosomes and repetitive sequences, posed challenges due to the complexity and difficulty in accessing biological material. The study focused on sequencing the genome of Eptatretus burgeri, a species residing in the Pacific. The researchers utilized advanced chromosomal proximity techniques (Hi-C) to generate data up to 400 times the genome’s size and assembled it at the chromosome level.
By comparing gene orders with other vertebrates, including sharks and humans, the researchers resolved a significant debate in genomic evolution regarding the number and timing of genome duplications. The study revealed that the common ancestor of all vertebrates experienced a complete genome duplication. Subsequently, the lineages leading to modern mandibular and non-mandibular vertebrates diverged, each independently multiplying their genomes, with mandibular vertebrates duplicating and non-mandibular vertebrates tripling their genomes.
In addition to genome sequencing, the research encompassed an analysis of myxini embryos’ functionality in Professor Shigeru Kuratani’s RIKEN laboratory. Another facet investigated the potential impact of genome duplications on vertebrates, collaborating with Professor Phil Donoghue from the University of Bristol. This multidisciplinary approach provides valuable insights into the evolutionary history of vertebrates, shedding light on the emergence of key characteristics such as brain structure, sensory organs, and increased regulatory complexity.
