With the sea star, also understood as the starfish, this isnt the case. A worldwide group of scientists used hereditary and molecular tools to map out the body of starfish, creating a 3D atlas of their gene expression. Starfish, along with sea urchins and sand dollars, belong to a group of animals called echinoderms. With these, they created a 3D map of gene expression in the sea star to recognize where specific genes are being expressed during the advancement phase. In starfish, numerous of these trunk genes arent expressed in the ectoderm.
“When we compared the expression of genes in a starfish to other groups of animals, like vertebrates, it appeared that an essential part of the body strategy was missing. The genes that are normally associated with the patterning of the trunk of the animal werent revealed in the ectoderm,” Jeff Thompson, study author, stated in a press release.
Micro-CT scan of sea star revealing the skeleton (grey), digestion system (yellow), nerve system (blue), muscles (red) and water vascular system (purple). Image credits: University of Southampton.
An international team of scientists used hereditary and molecular tools to map out the body of starfish, creating a 3D atlas of their gene expression. They found that the “head” of a starfish isnt in any one place. Rather, the headlike areas are dispersed, with some in the center of the sea star in addition to in the center of each limb of its body.
” The response is much more complicated than we expected,” Laurent Formery, the lead author of the brand-new research study and a postdoc scientist in the labs of Stanford University and the University of California, said in a news release. “It is just weird, and more than likely the evolution of the group was much more complex than this.”
Starfish, along with sea urchins and sand dollars, come from a group of animals called echinoderms. They have an unique fivefold symmetric body plan, which implies that their body parts are organized in five equivalent areas. This is different from their bilateral forefathers, which have a left- and right-hand side, as seen in people and many other animals.
They used a mix of high-tech molecular and genomic techniques to comprehend where various genes were expressed during the development and growth of sea stars. This consisted of RNA tomography to identify where genes are revealed in tissue and in situ hybridization, a method that zeroes in on a particular RNA series in a cell.
This then recommends that sea stars and other echinoderms might have evolved their five-section body strategy by losing the trunk area of their bilateral ancestors– so starfish are “mostly head-like animals”. This would have permitted the echinoderms to move and feed in a different way than bilaterally balanced animals, suggesting their development was far more complex than anticipated.
The research study was released in the journal Nature.
In the study, the scientists compared the molecular markers of a sea star to other deuterostomes– a broader animal group that includes echinoderms and bilateral animals, like vertebrates. As they share a common ancestor, the researchers can compare their advancement and discover more about how echinoderms progressed their distinct body plan.
With these, they produced a 3D map of gene expression in the sea star to identify where specific genes are being expressed during the advancement stage. Particularly, they mapped the expression of genes that manage the development of the ectoderm. This is known to mark the front-to-back patterning in the bodies of other deuterostomes.
Mapping stars
When looking at a fish, its extremely clear which end is the head and which is the tail. With the sea star, also understood as the starfish, this isnt the case. Its five identical arms have puzzled researchers for centuries. Lots of biologists have tried to understand what constitutes the head of the starfish and now, for the very first time, they may have found out the most likely response.
They discovered this pattern was related to the midline-to-lateral axis of sea star arms, with the midline of the arm representing the front and the outermost lateral parts being more like the back. In addition, in deuterostomes, theres a set of genes revealed in the ectoderm of the trunk, which is the “main body” (instead of the “head”). In starfish, numerous of these trunk genes arent revealed in the ectoderm.
