Egg-born monotreme mammal genomes, platypus and echidna, were published in the prestigious journal Nature, providing a valuable public resource for research in mammalian biology and evolution, with claims for their conservation and health.
Monotremes exhibit a unique combination of mammalian and reptilian traits and form the group of living mammals farthest, and least understood. Their genetic plan provides a basic overview of the specific biology and evolution of all mammals.
Platypus and echidna are the only mammals that lay eggs, so they are a way of understanding the change in reproductive strategy from egg-laying to juvenile production in their young. -all other mammals. “
Marilyn Renfree, Professor, School of Biosciences, University of Melbourne
“While short in egg, they are one of the three main egg proteins used to make the yolk in chickens, but after laying both platypus and echidna complex milk is like other mammals to support their offspring during the long lactation period. . “
The research was the result of an international collaboration involving Australian scientists from the Universities of Melbourne, Adelaide, Sydney, LaTrobe University, as well as researchers from China, Japan, the USA and Denmark.
The 40 researchers brought together expertise in bioinformatics, cytogenetics, developmental and molecular biology to extract and study the first echidna genome and a highly developed high-quality platypus genome sequence.
Professor Frank Grutzner from the University of Adelaide, who co-directed the study, said the findings were important.
“More than 15 years ago we discovered that monotremes have different sex chromosomes than all other mammals,” Dr. Grutzner said.
“This discovery transformed our understanding of mammalian sex chromosome evolution but also raised fundamental new questions. With the new genomes we can now address important questions about how sex chromosomes hold control of monotreme sexual development, and how they evolved. “
The co-author of the study, University of Adelaide Dr Linda Shearwin-Whyatt, said the system for safely removing the oxygen transport, hemoglobin from the blood was thought to be common to all moms.
“We were surprised when we found out that the system was missing from monotremes, meaning it had recently evolved into the ancestor of all other mammals,” she said.
In contrast, Dr Fenelon at the University of Melbourne reveals that monotremes have lost several major tooth genes and their adult teeth.
Professor Jenny Graves of LaTrobe University said the egg-laying monotremes, unique in Australia, help answer some of our deepest questions about -m mammalian growth.
“We last shared an ancestor with the platypus and echidna about 180 million years ago, so comparing the monotreme and human genomes can tell us about our common ancestor,” Dr. Graves said.
Knowledge of monotreme reproduction is also relevant for capture conservation and breeding programs. Researchers are thrilled that the new genome sequences also provide a roadmap for the genetic control of endangered echidna populations and interesting new directions for drug development through the detection of novel peptides in platypus venom.
Dr Renfree said the new understanding would help preserve these unique and special mammals in Australia.
Source:
Magazine Reference:
Zhou, Y., et al. (2021) Platypus and echidna genomes reveal mammalian biology and evolution. Nature. doi.org/10.1038/s41586-020-03039-0.