An Age Old Question

You may be thinking of many different questions this could possibly be about, such as: "Which came first, the chicken or the egg?" - nope! Or, "Why did the chicken cross the road?" - try again! How about, "What is the meaning of life?" - wrong.

The correct answer is, "Are viruses alive?"!!

This has been very controversial in the scientific community for many, many years. The most commonly accepted answer is, no. The basic requirements for an entity to be considered "alive" are as follows: capability of homeostasis, being composed of one or more cells, presence of DNA and RNA, metabolic activity, ability to grow, adaptability, response to stimuli, and the ability to reproduce.

Based on these qualifications, viruses fall short. However, a group of scientists in Illinois disagree. Since one of the main arguments is that viruses are not able to survive outside of a host, this group argues that there are other living species that rely on a host to complete their life cycle, so technically without that host, the other organism would cease to live and/or reproduce.

Other supporting evidence these researchers are gathering and focusing on is the composition of a tree of life that includes viruses by tracking their evolutionary history through their protein folds. These folds give a virus its shape and hundreds of these folds have been found in both viruses and cells. Also, viruses have been able to adapt and become infectious to cells that had been previously resistant, which is said to be the "hallmark of parasitism." Only about 5% of the estimated population of viruses have been discovered and sequenced, so it is possible that the key to this question lies in that 95%!

Do you think this is enough to change your mind? If not, what evidence (if any) would satisfy your skepticism? Comment below!!

Sources:
http://www.sciencedaily.com/releases/2015/09/150925142658.htm
https://en.wikipedia.org/wiki/Life
http://www.biolegend.com/NewsLegend/091615blog/AreVirusesAlive2.png

The New Workhorse of Gene Editing - CRISPR/Cas9

So what is CRISPR/Cas9? (I don't know why, but to me the first part sounds like how some people like their bacon) CRISPR stands for "Clustered Regularly Interspaced Short Palindromic Repeats" - quite a mouthful, huh? - and Cas refers to any CRISPR-associated genes/proteins. CRISPR sequences originate from prokaryotes and are most abundantly found in archaea. These organisms use this mechanism as their "immune system" as it allows them to cut beneficial genes from outside DNA sources and incorporate them into their own genome or to just inactivate harmful DNA from invaders, such as viruses or other bacteria.

There are multiple Cas proteins, but Cas9 is the main one associated with gene editing and silencing. Different forms of this protein play various roles in the editing process; for example, one form can induce double-stranded DNA breaks, while another form may only be able to bind to the target DNA and control the expression of that gene. This system is only 3 years old so there is much more potential to be discovered!


More detailed explanations and more can be found at the following sites:

https://www.neb.com/tools-and-resources/feature-articles/crispr-cas9-and-targeted-genome-editing-a-new-era-in-molecular-biology

https://en.wikipedia.org/wiki/CRISPR


Hope you enjoyed it!
-Michelle

Cats aren't the only ones that play with balls of yarn

Ever seen a cat playing with a ball of yarn? If not, watch this adorable video (or watch it anyway for guaranteed grins and giggles). 

The kittens are super cute, but the ball usually gets destroyed and yarn goes everywhere. However, with scientific advances, the yarn ball can fight back! Well.... not against a cat, but how about cancer?! In a recent study, researchers have developed a highly effective way to introduce gene editing proteins into living cells using a nano-vesicle in the shape of a clew (a.k.a. a fancy name for a ball of yarn). This structure is completely made of DNA, so the cell can easily recognize it and take it in. Inside, it contains a CRISPR-Cas9 complex, which is responsible for the gene editing function. A single guide RNA (sgRNA) can be designed to target certain areas of the genome to let the complex know exactly which DNA segments to cleave before they can be corrected.

So basically, the tiny ball of yarn sneaks its way into a tumor cell, for example, makes its way into the nucleus like nothing is going on, searches the genome, and if/when the sgRNA finds a bad gene, then bam! it sends the CRISPR-Cas9 complex to chop up the bad portion and then put it back together the way it should be through normal DNA-repair pathways. This will hopefully allow the cell to regain its original function and stop displaying tumor cell properties, such as the ability to bypass cell-division checkpoints, mobilize itself, or even avoid apoptosis, which are necessary qualities for tumor cells to proliferate and eventually develop into a cancerous cell line. So the next time you see a ball of yarn, think of the endless possibilities!!

Until next time!
-Michelle

1. Wujin Sun, Wenyan Ji, Jordan M. Hall, Quanyin Hu, Chao Wang, Chase L. Beisel, Zhen Gu. Self-Assembled DNA Nanoclews for the Efficient Delivery of CRISPR-Cas9 for Genome Editing. Angewandte Chemie International Edition, 2015; DOI: 10.1002/anie.201506030

Not familiar with the CRISPR-Cas9 system? Come back next week for a quick explanation!