Chromosomal Gene Analysis of Cephalopods Give Scientists a Sneak Peek Into the Their Evolution

 

A Cephalopods nervous system is about as weird as the creatures’ external features. The evolutionary pathway that led to this infinitely complex nervous system has long been cloudy and less understood than other aquatic species. Recently, chromosomal assemblies of three cephalopod species – two squids  know as Doryteuthis pealeii and Euprymna scolopes along with an octopus species known as Octopus bimaculoides – have allowed scientists to better recognize which specific genes are present and in what order. This newfound knowledge can allow geneticists to further study components within the genome that are driving the expression of these genes (Nature).

Cephalopod genomes are notably different than those found in humans. Genomes within the two species of squid were found to be about 1.5 times larger than that of humans. While the Octopus’ genes more closely resemble a humans at about 90% size. Furthermore, it is found that while humans evolved through meiosis, a process in which two rounds of genome duplication occurs, a cephalopods evolution does not involve whole genome duplication, but instead undergoes “immense genome rearrangements” according to a Science Daily article. Which makes sense given that cephalopods started evolving 300 million years before humans existed. Discovery of this difference in duplication is a foot forward in finding out how these complex and highly intelligent creatures have evolved and thrived.

Change Occurring in the Cytoplasm

 

The article Squid Edit Their Genetic Material in a Uniquely Weird Place details an important discovery of an ability that a certain individual can do unlike most known animals. The Longfin inshore squid or the Doryteuthis pealeii is the only known animal to be able to edit their mRNA or messenger RNA outside of the nerve cell nucleus. Generally most animals are able to make edits to their RNA but do so rarely and when they do they are done within the nucleus and then exported out. The unique ability that the Longfin inshore squid has is that it can do its RNA edits in the cytoplasm.

    The method in which the squid edits their RNA is similar to how CRISPR is used to make edits in DNA. CRISPR has allowed for DNA sequences to be modified to correct genetic defects that are threatening and even aid in the genetic modification of crops. But unlike editing DNA which happens to be a bit tricky because errors are permanent, editing the RNA isn't as dangerous and unlikely to repeat because RNA is broken down. Studies show that it is possible that squid is able to edit their RNA in both the nerve cells (neurons) that send signals to the brain and throughout the body and in the cytoplasm at the same time.With this new discovery it's important to consider this as a possible to track to discovering how to develop therapies that would be useful to treat chronic conditions. While more research is needed it would benefit the medical community to find other alternatives to treat chronic conditions besides just prescribing medications. 

Bacterium using sRNA to communicate with squid host relationship

This article is with regards to the Hawaiian bobtail squid and the mutualistic relationship that it has with a bacterium, V. Fischeri. The bacterium is known to be recruited by squid in a symbiont manner in the light organ to aid in camouflage during night time hunting of the squid. The bacterium creates sRNA in which helps communicates with the squids immune response, and ultimately act as an inhibitor to gene response of the immune system via these signals. This creates an overall mutualistic relationship between the two organisms in which the bacteria is allowed to survive within the tissues of the squid while it aids in the "fitness" of the animal. The article provides a brief understanding of how these mutualistic relationships between these organisms are established and that the information previously gathered on the genetics of the bacterium are not completely understood. It shows that some bacterium do have the ability to communicate between the host and create a relationship based on passing information through RNA. Overall the article is rather interesting in terms of genetics and the way some relationships may form between even the smallest organisms and their ability to manipulate the environment using RNA to form this relationship. It provides perspective more in depth into the animal world and understanding that there may be a lot more of these relationships that are behaving in the same manner, even in a parasitic situation, and being able to understand this may help with creating gene response based on the communication from the RNA to regress other harmful or serious genetic issues if understood to the maximum potential. 

https://www.sciencedaily.com/releases/2020/11/201119103101.htm

https://journals.plos.org/plosbiology/article?id=10.1371/journal.pbio.3000934

Genetically Altered Squid May Pave the Way to New Research Methods

Image shows normal coloration/pigmentation in squid on the left and genetically altered squid on the right 

 Cephalopods have been studied extensively in the field of neurobiology. When conducting research, scientists always have had trouble figuring out the genetics to many unique traits that cephalopods have. Specifically, their ability to change color and texture of their skin as well as their intellectual level. Not being able to see the genomic structure of some of these processes have left scientists stumped. In this article, they talk about how scientists were finally able to alter the gene for coloration in squid. After figuring out how to accurately inject genetic information to developing embryos, scientists were able to alter the coloration in newly developed squid. By being able to do this, they are finally able to start understanding cephalopods at a genetic level. This is extremely important in the neurobiological field as cephalopods are studied extensively for their unique traits. This allows scientists to understand the processes as a whole as well as being able to further enhance studied to grasp a better understanding as to how and why these processes occur. 

    Cephalopods have always been interesting to me and I love reading about them in my own time. Seeing that scientists have been able to finally open the world of genetics into cephalopods is truly an exciting time. These creatures have a complex world of their own, which is highly studied especially on a neurological standpoint. Their intelligence levels are remarkable and their ability to also change color and texture of their skin is so unique. To be able to finally see these traits in a genetic level will help with research in many ways. Understanding their cognition and neural function on a genetic level may be able to help with projects in the neuroscience and medical fields. 

Link to the article

Link to supporting articles: NPR article 

Giant Squid, Giant Eyes, but Rather Small Brain Lobes

Many researchers have questioned the deep sea squid's large eye size compared to other creatures who have a much smaller eye size, such as the cephalopods. Research has shown that even though squids have the largest eye orbit in the animal kingdom, they also have a very small optic lobe. This explains that squids do not rely on visual cues for communication like the cephalopods do because the optic lobe, which integrates visual information with motor tasks, is reduced. This new research is of current fascination because it goes against common anatomical sense and raises the question for future on whether there is some other underlying biological reason for this difference in sea animals.

Article

Squids Can Change Their Genes - And Maybe Ours One Day, Too

A recent study done by Dr. Eli Eisenberg at Tel Aviv University has come to the conclusion that the longfin inshore squid is capable of modifying its own genome sequence. While RNA is known to, typically, transcribe the gene sequence of an organisms DNA without purposeful deviation, some animals have been observed changing the individual nucleotides on the transcribed RNA. More frequently, members of the cephalopod group, including the octopus and squid, have been using this technique of altering their RNA in response to temperature changes and environmental needs. The study discussed in the popular science article focused on the longfin inshore squid, and found that 60% of the transcribed RNA sequences were purposefully edited. Because squids – and other cephalopods – have such complex nervous systems, researchers are theorizing that these changes are a way for the squids to adapt more easily to environmental changes. In fact, in light of the damages inflicted by humans on the climate and especially in the ocean, squids appear to be doing well  , especially compared to the declining numbers of other marine species. Its possible, even likely, that the ability to alter its RNA is what’s allowing the squid to adapt to and survive in the increasing strain of the environment. Beyond just the impressive skills of the squid, this finding bears implications in the human world. Because some pretty serious human diseases are results of issues in RNA transcription, the ability to selectively edit RNA sequences could come in handy. Research is starting on how this discovery can be used to make humans just as hardy as our aquatic friends. 

The DNA ‘blueprint’ of the squid is enrich by prolific RNA editing

According to an article on science daily a new study found that, the squid Doryteuthis pealeii, uses a great amount of RNA editing. When the genetic information is passing from a genomic DNA to messenger RNA to the synthesis of proteins the information is changing during its transition, to perfect the type of proteins created. Yet RNA editing was known to be sparingly used, it was established that the use of RNA editing on mammals and flies were narrow. But now it’s acknowledged that 60% of the RNA transcript it’s edited, after sequences of RNA and DNA from the squid brain was compared. These studies were done by the investigator Joshua Rosenthal and colleagues. Rosenthal found in the squid brain has 57,000 recording sites which surpass the 100 sites known in the humans; the high number of recording sites creates remarkable protein diversity. Because of this diversity it allows the squid to have a better physiological reaction to the environmental variables, like temperature, professor Rosenthal will be challenging his hypothesis during the summer of this year.