Hox genes and insect wings: evidence for a combined origin.

Questions about how insect wings evolved has generated much debate between whether they originated in accordance with the pleural or tergal hypotheses (Linz and Tomoyasu, 2018). However, Linz and Tomoyasu (2018) provide evidence for another hypothesis, that both the pleural and tergal areas contribute to the formation of wings, via their analysis of the tissues of the non-wing bearing abdomen. It was found by Linz and Tomoyasu (2018) that through the suppression of certain Hox genes, abdominalA (abdA) and Ultrabithorax (Ubx), within Tribolium (Flour beetle) that an area of wing tissue started to form from both the pleural and tergal regions. This was further investigated by Linz and Tomoyasu (2018) through RNAi.

Click here for the article.

References

Linz, D.M., and Tomoyasu, Y., 2018. Dual evolutionary origin of insect wings supported by an investigation of the abdominal wing serial homologs in Tribolium. PNAS. 115: E658-E667; DOI:10.1073/pnas.1711128115

Image: Linz, D.M., and Tomoyasu, Y., 2018. Figure 6 from Dual evolutionary origin of insect wings supported by an investigation of the abdominal wing serial homologs in Tribolium. PNAS. 115: E658-E667; DOI:10.1073/pnas.1711128115. http://www.pnas.org/content/early/2018/01/08/1711128115 Accessed: 03/06/18.

Victoria Lockwood

HOX genes at the movies

Apparently (I haven't seen the movie) HOX genes are evoked in the new film Annihilation (link for trailer).  In the film, as scientists explore some mysterious Area X they find plants in the shape of human bodies, which they attributed to the plants having human HOX genes.

THIS article in Inverse explains.

Water Bears and Hox Genes

Tardigrades, more commonly known as water bears, are capable of occupying many ecological niches--including arctic glaciers, Lake Michigan, and a Japanese parking lot, where a new species was recently discovered. This is in part due to the diverse morphology of tardigrades' body segments. In early development, Hox genes play a significant role in segmentation development. Researchers have recently discovered that several Hox genes were lost early in the tardigrade lineage resulting in the loss of the intermediate region of the body plan--corresponding to the thorax region in insects. The researchers note that this loss demonstrates that a body plan of an animal may be the result of a large loss of body.

Find the original article here
Read about the newly discovered tardigrade species  here

-Leanne Chambers

Researchers find the ancestral function of the retinoic acid, an essential molecule in the evolution of vertebrates

Researchers at the University of Barcelona have identified a role in gene expression for retinoic acid, important in the embryonic development of vertebrates. The acid seems to regulate the gene expression in cell proliferation and differentiation during the embryonic development and the formation of body symmetry patterns. The researchers showed that retinoic acid controlled cell differentiation in the species P. dumerilii and aided in the proper formation of neurons. This acid likely has roots in the evolution of bilateral symmetry, which is a very basic shared trait amongst Chordates.

Link to news release here.

Kim Foecke

HOX genes and chinese cattle

This article published in Gene caught my interest as it relates to the evolution of body size.  The SIX4 gene is critical to muscle regeneration and the early stages of ontogeny.  Transcription factors for it also correlate with body size measurements such as withers (shoulder) height, back fat thickness, chest depth and circumference, and loin area.  While all this is mostly motivated by economic reasons, its ties to overall body size are interesting as well.  This study found 7 SNPs in the promoter region for SIX4 which ultimately lead to 18 transcription factor compositions.  Two of the resulting polymorphisms were correlated with higher fat content and generally larger cattle.  I would be interested to see if these transcription factors correlate to overall body size and/or fat content in primates as well.

Role of HOX genes in colon cancer development

As colon cancer is one of the leading cause of cancer death in US many research are going on to find treatments for this threatening disease. Recent discoveries indicate the role played by two specific Hox genes HOXA4 and HOXA9 in colon cancer development. As we know, Hox genes are involved in the regulation of stem cells, Dr. Boman and other researchers found that the over expression of these 2 specific HOX genes resulted in stem cell overpopulation, hence, colon cancer development. They proposed that decreasing the expression of these 2 Hox genes could be used as a treatment to prevent the replication of colorectal cancer stem cells.

Link: https://www.news-medical.net/news/20180131/Scientists-discover-role-of-two-specific-HOX-genes-in-colon-cancer-development.aspx

Axelle

We had the genes for walking before we left water!

New and exciting research now provides evidence that our ancestors developed the neural and genetic mechanisms for walking before they transitioned to land.

It was already known that some species of skates can move along the ocean floor by propelling themselves forward with small pelvic fins in a left-right motion. Their spine remains immobile. This style of locomotion also characterizes locomotion in tetrapods (mammals, birds, reptiles), so in essence, some species of skates can walk!

A team of researchers did RNA sequencing to see what genes are expressed in the motor neurons in skates. Skates, they found out, express many of the same type of motor neurons expressed by land mammals such as humans. Because neurons can't fossilize, this study published in Cell, will be paramount to how we understand limb development and, likely, bipedalism in humans.

If you want to see 'skate walking', follow the link to this video and watch between minute 1:07 and 1:22!

- Elizabeth (Liz) Tapanes