On The Search For A Gene

As I am on the search for a drosophila gene, I’ve come across several genes that have caught my interest. Some are closely related to each other and some are very different, almost polar opposite in terms of function. They all surround the d. melanogaster species, which is mostly studied. In researching, I did not have any specific genes in mind. As I sat there, my first thought was, “why not start with an embryo? Just start from the beginning.” I started with embryo development, and then went on to body or mesoderm functions. From there, it scattered and went to sexual behavioral genes. I did come across some gene that seemed interesting at first, but didn’t quite catch my eye. Ironically, most of the genes I had researched had funny names, first starting with tinman.

We’ve all heard the story of Dorothy in the Wizard of Oz, and she meets a particular set of people along the journey to Oz. One person she meets is a man made out of tin. He can talk, move (if oiled), but he has no heart. Thus, the drosophila mutant does not grow a heart giving the name tinman. On Mendeley, I found an article titled “The gene tinman is required for specification of the heart and visceral muscles in Drosophila”. This article provides the genetic and developmental reasoning behind this mysterious gene. Reading more into this article, I discovered that the gene twist is necessary for mesoderm formation and tinman gene is not expressed in twist mutant, therefore gave an interest in the twist gene.

In the article “twist: a myogenic switch in Drosophila” from Mendeley, it explains that the transcription factor twist initiates mesoderm development, which includes the formation of the heart, somatic muscle, and other cell types.  It also claims that altering amounts of Twist reveals high levels of twist are required somatic myogenesis and stop the formation of other mesodermal formations. Another article I found quite enticing is “A Drosophila model to study the functions of TWIST orthologs in apoptosis and proliferation”, also on Mendeley.  It covers the idea that twist is a potential oncogene antagonizing the P-53 dependent apoptosis, or the idea that human twist is able to induced cell proliferation in drosophila.

As I started to explore deeper, I discovered the gene called tribbles on sdbonline.org. It gives information about what it is, its role in drosophila, and its affects. It explains that tribbles is a novel cell regulator and is critical during development. It affects the number of germ cell divisions during oogenesis. The article also explains that tribbles can lead to gastrulation defects and coordinates entry into mitosis. An article from Nature.com states that SKIP3 is an ortholog of tribbles and it is involved is slowing cell-cycle progression during development.

Another gene that really caught my eye was called fru, or fruitless gene. This gene controls sexual orientation. On Sciencedirect.com, an article discusses that the fru gene produces both sex-specifically and non-sex specifically spliced transcripts. They also examine the central nervous system to better explain and understand the fru gene’s behavioral role. An article from Stanford News Online gave an interesting outlook of this gene, phenotypically. It explains that a fru gene male with a normal copy of the gene lists one wing and vibrates it in a rhythmic song. Males with a small alteration or mutation of the fru gene have subtle changes to their songs. Other males with strong mutation were unable to produce a song, and can only click their wings.

Looking back at all the genes I have research, I have not yet decided on which gene I would like to choose. All of these genes are very interesting and I would love to really explore them all, but I must decide which is far more interesting and which one really intrigues me. I am leaning towards the fru or fruitless gene because it’s a gene that determines the drosophila fly’s meaning in life, which is to reproduce. I have plenty of more research to do, more time to think, and I know my decision will come easier then.

Introduction

 Drosophila is one of the major organisms for the study of genetics, evolution, and population biology. It has been used to discover the fact that genes were related to proteins and the study of genetic inheritance rules. In more recent studies, it was used for developmental biology and how such a complex organism arises from a simple fertilized egg. Most of the attention has been focused on embryotic development but there are also interests in some adult structures develop in the pupa such as the compound eye, wings, legs, and other organs. It has been used for research for almost 100 years, and now, many scientist are interested and researching on the many different aspects of Drosophila. According to Genetics-gsa.org, there have been many awards granted towards this research. It had won the Nobel prize in medicine/physiology to Ed Lewis, Christane Nusslein-Volhard and Eric Wieschaus in 1995. Drosophila was the perfect organism to research toward human health. We already know so much about this tiny organism- it has a short life cycle of two weeks, it is easy to understand and handle, it doesn't costs a large amount of money to get our hands on, and it's easy to keep large numbers.

Because they are a model organism of many aspects of biology, these flies and the entire genome have recently been fully sequenced. There are 12 fully sequenced species, such as Drosophila psuedoobscura, D. persimilis, D. willistoni, D. mojavensis, and D. virilis to name a few. This data has used to correlate evolutionary genome comparisons.

The species I had chosen is Drosophila virilis.

It has been said that D. virilis originated somewhere in the ancient deciduous forest of China or arid regions, and remained isolated from the rest of the species. This species live near the watersides. In north and in high altitudes, these species have only on generation a year. They are larger than many of the other Drosophila species. They are dark colored, male tends to have a red abdomen, and they do not have sex combs in their front legs. They also have cross-veins on their wings and even larger cross-veins around it along the shadow. The females are able to recognize species-specific characters of the male song, but with this type of species they do not need to hear the song before mating. They also have a high thermotolerance and a high tolerance for ethanol, allowing them to adapt and survive in many different environments.