In the beginning, life was simple. Then, about half a billion years ago, the biology is complicated. Similar cells decrease in the chains of consent and divide the chores between them, developing the first members of the animal kingdom.
Exactly what this prototype animal looks like has long been the subject of debate. A new study has revealed that the line between ancient germs and animals at the beginning can be crossed through an early form of stem cells.
Today, biologists tend to support one of the two contenders for the first & # 39; Earth beast. In one corner, there is Team Sponge. In the opposite corner, Team Comb Jelly.
Each camp has a good reason to suspect that the ancestor of the Animalia kingdom is like their particular phylum that is closer than the other.
Sponges have the kind of anatomy we all want to think of primitive animals. [1
Transcriptome analysis is rapidly becoming a tool of choice for researchers who want to know how cells behave with identical genomes in specific ways.
"This technology is only used for the past few years, but it has helped us finally address an old age question, discovering something completely contrary to anyone suggested," said biologist Sandie Degnan.
"Now we have the opportunity to reconsider the steps that gave the first animals, the basic rules that are the sole cell of a multicellular animal life."
Like all animals, the cells that make up our bodies are individually suited for performing specific tasks. Differentiation sets our organisms apart from the consistent clusters of cells that promote the hope of survival in numbers.
For over a century, biologists thought the first different colonies as close relatives of modern phylum porifera members – the humble sponge.
Because cells called choanocytes that shine in their strengths seem to be suspicious as free life, tailed organisms called choanoflagellates, biologists consider the case closed at first animals in the world.
"Biologists for decades believe that existing theory is a no-brainer, because the choanocyte of the sponge looks similar to the single-celled choanoflagellates – the organism considered to be the closest relative of animals, "Degnan says.
But as all the biologists, are deceiving.
Choanoflagellates may look like they just work on a sunny day 600 million years ago to make sponge, but research shows that there are ficant differences in their genomes and biochemistries.
To further test the connection, Degnan and his research team compared the transcriptomes, behaviors, and life cycles of three different types Amphimedon queenslandica sponge tissue with a choanoflagellate and two other similar, single celled organisms.
It's not like comparing genetic libraries to sponges and pre-animal cells, and more like testing their library cards to see if they are reading from a shared book list. And it turns the sponge cells and the choanoflagellates are not in the same book of the club after all.
It is even more surprising that the library card belongs to an unidentified type of sponge cell called pluripotent mesenchymal archaeocyte. Unpredictable spongy cells look more like an ancestor of early animals than those that have been changed into smoke or skin cells.
"We have found that the first multicellular animal probably does not look like modern sponge cells, but is more like a collection of convertible cells," said Degnan's colleague, scientific marineal Bernie Degnan.
"The grandmother's grandmother of all cells in the animal kingdom, at last may be like a stem cell."
In some respects, it makes a lot of meaning. Animals are made up of a wider range of cell types, compared to plants and fungi.
Developing a talent for rapidly changing faces can provide our animal ancestors one side as they combine. It is possible that the first beasts are separated by developing regulatory systems that allow many differentiated cell types to exist at the same time in the same population.
This understanding has implications beyond our evolution.
These are the early days for the Team Stem Cell, but it is clear that the first animal's debate is far from qualitative.
This research was published in Nature .