about rini

First, a bit of background and vocabulary to help us understand Rini's research. DNA is a long, connected strand of molecules (four different types, repeated in varying patterns) that gives instructions for the development and maintenance of living things. All living things have DNA, but the instructions for the development and maintenance of a human are different than the instructions for a house cat or a fern, and so the DNA sequence (the order in which its constituent molecules are found along the strand) looks different between those organisms. In total, human DNA has around 3 million of those building block molecules, and specific stretches of it with specific sequences that give specific instructions are called genes. If one were to "read" DNA, one would encounter certain stretches that give instructions (genes, or "coding DNA"), and long stretches in between genes that don't give instructions for anything in particular ("non-coding DNA"). All the genetic information in an organism put together is often referred to as its genome.

The sequence of the molecules in DNA changes often due to mutations, or mistakes that occur when DNA is copied and replicated. Sometimes, these changes don't make much of a difference, but other times they can benefit the organism or result in illness or death. Occasionally, these "new" genes can get passed down to offspring, and this is part of the process of evolution.

There are some genes that have been "conserved" across the tree of life, meaning they evolved a very, very long time ago and are so important that the instructions and DNA sequence haven't changed much, if at all. For example, a gene that dictates the development of body plans in animals (like where, how, and when limbs form in the womb or egg) looks almost the same in fruit flies as it does in mice. So much so, in fact, that scientists have been able to swap the DNA from one animal to another and the fly or mouse develops perfectly naturally!

Until recently, most scientists believed that genes that are essential for life, like the ones that determine body plans, do not evolve quickly, or much at all--meaning, their DNA sequence and the instructions that they give would look the same for a very, very long time. In November of last year, Rini, her research advisor, and a team of collaborators released the results of a study that explored the function of rapidly and recently evolving genes, with some very surprising and important results.

Rini and her team were following up on different researchers' findings from 2010. Those scientists found that, when they examined the purpose of 200 relatively new and rapidly changing genes in Drosophila (druh-SAW-fill-uh), a genus of fruit flies (a genus is a particular grouping of species), more than a quarter of them were necessary for the flies' survival. Interestingly, when they looked at "old" genes, they found that about the same ratio were essential for survival--and that was lower than they expected. This was both confusing and inspiring to many scientists because it went against the previously held belief that very important genes do not change much over time, if at all.

In her recent study, Rini decided to focus on a "family" of genes called ZAD-ZNF. These genes are transcription factors, and their role is to regulate how and when other gene instructions are followed, if at all. When she looked at how old the genes were and how essential they were, she found that 61 of these genes were present in all Drosophila genomes she examined, meaning they were "old"--over 40 million years old, to be precise! Many of them served essential purposes. However, 12 of them were rapidly evolving. Surprisingly, a majority of these rapidly evolving genes were also essential in Drosophila melanogaster, a particular species in the Drosophila genus that Rini and many other scientists study.

One interesting finding about these rapidly changing essential genes is that many of them "live" in parts of the flies' DNA that was thought to be mostly non-coding DNA. The fact that such important genes exist in these relatively unexplored regions of DNA could give researchers new places to look for therapies or cures to rare medical conditions or diseases.