In the study titled, “Experimental Approach Reveals the Role of alx1 in the Evolution of the Echinoderm Larval Skeleton” by Hiroyuki Koga, the alx1 gene was proven to be necessary for the acquisition of the larval skeleton and played a necessary role in the evolution of the larval skeleton (Koga, 2016).
In the study, echinoderm larvae were the model organisms used to see if alx1 is the gene that is necessary for the attainment of the larval skeleton. There are five classes of echinoderm, which include sea urchins, sea cucumbers, brittle stars, starfish, and sea lilies (Koga, 2016). The transcription factors, Ets1/2, Alx1, and Tbr, control the differentiation of primary mesenchyme cells that form the larval skeleton. Scientists pinpointed Alx1 to see if this gene was important with the evolution of the larval skeleton by inducing the expression of alx1 in starfish that do not have a skeleton.
To induce the expression of alx1 in starfish, Koga and his team inserted mRNA that coded for Alx1 into the eggs of the starfish (Koga, 2016). This was done by utilizing microinjection. The goal was to increase the cell numbers of skeletogenic cells, and green fluorescent protein was inserted into starfish embryos, specifically the nuclei. Researchers measured the effects of inserting different types of mRNA. When the researchers inserted high levels of mRNA resulted in prevention of gastrulation (Koga, 2016). This then led to a halt in the process of development. Low levels of mRNA led to a high production of skeletogenic cells in sea urchin. But in starfish embryos, this did not occur (Koga, 2016).
Koga’s team demonstrated that alx1 was necessary for the larval skeletons of sea urchins and sea cucumbers (Koga, 2016). However, alx1 was not expressed in starfish embryos, but was rather highly expressed in adult skeletogenesis. Koga and his team concluded that their data did not support the previous claimed statement that there is high expression of alx1 in embryonic and early larval stage of the starfish. There team also found that alx is replicated in the echinoderm lineage (Koga, 2016). Specifically, this study proved that in echinoderms, the expression of alx1 occurs more frequently in skeletogenic cells of adult and larvae. Starfish do not have tube foot spicules and in starfish, alx1 is expressed in the tube foot. Therefore, Koga and his team concluded that alx organically was necessary for coelomic development (Koga, 2016). One repeated paralog was involved with skletogenesis and researchers therefore concluded that alx is involved with the creation of the larval skeleton and the calcareous skeleton (Koga, 2016).
1. Koga, Hiroyuki, Haruka Fujitani, Yoshiaki Morino, Norio Miyamoto, Jun Tsuchimoto, Tomoko F. Shibata, Masafumi Nozawa, Shuji Shigenobu, Atsushi Ogura, Kazunori Tachibana, Masato Kiyomoto, Shonan Amemiya, and Hiroshi Wada. "Experimental Approach Reveals the Role of alx1 in the Evolution of the Echinoderm Larval Skeleton." PLoS ONE. Public Library of Science, 11 Feb. 2016. Web. 24 Apr. 2017.