Greetings, I am Ph.D. seeking student in my 3rd year at FSU. I'm currently studying developmental molecular biology with soon to be famous Andy Johnson; the lab is primarily interested in mesodermal patterning, the molecular aspects of germ cell formation, and most recently the evolution of developmental mechanisms . The students in the lab are also very interested in ethanol consumption and exploiting the hox genes that are required for multiple wing formation in G. gallus (not to mention the holy grail of hox genes- BJT). Actually, besides eating wings and throwing back a few cold ones, the molecular evolution of germ cell formation is what really interests me.
A picture of the lab taken at the annual Christmas "Lab Night Out" 1998, pictured from left to right- Jessica (little sis, Emory), Anthea (The Princess, UF), Myself, Tom (self proclaimed king of the lab), Brian (The thing), AJ (aka Commander McBragg), and Ferrell (medical school somewhere in the Caribbean) Not pictured but still loved, Merredith, Amy, and Jen (you may expect to see them in the 1999 Lab Night Out 'Beach party' photo...coming soon!).
Amphibians are widely used as model systems for studying the early embryonic development of vertebrates. Although many aspects of early amphibian development is very similar, frogs (Anura) differ radically from salamanders (Urodele) in the way that the germ cell lineage is determined. The frog germ line is endodermal and is formed by a deterministic mechanism similar to that seen in protostomes (such as C. elegans an D. melanogaster). In salamanders the germ cells are mesodermal derivatives and form by epigenetic mechanisms, which is in both regards, similar to higher vertebrates (such as mouse and human). Several genes known to govern germ cell development have been identified and these appear to be conserved in the animal kingdom. Mammalian forms of three such genes-- oct 3/4, dazl and vasa-- have been shown to be critical for germ cell determination. Along with Dr. Brian Crother and Dr. Mary White of South East Louisiana University, I am employing phylogenetic methods to analyze the homologous genes from frogs and salamanders to investigate whether the evolution of germ cell-specific genes reflects the mode of germ cell determination (salamanders being more similar to mammals) or the phylogenetic relationship of the organisms (salamanders and frogs being more closely related). Preliminary results suggest that germ cell-specific genes from salamanders are more closely related to the mammalian homologues than to the anuran ones, supporting the idea that the evolution of the genes tracks the mode of cell determination rather than the animal phylogeny.
It is also a goal of mine to understand the evolutionary history of amphibians, not just their developmental similarity with mammals. Two different theories involving the origin of amphibians have been argued. One polyphyletic based theory has modern amphibians being represented by two independent derivations from lobe-finned fishes. This seems plausible when one considers the extreme differences in the amphibian developmental processes such as somitogenesis, notochord formation, mesoderm induction, and as discussed earlier, the method of germ cell formation. The other theory, now widely accepted, simply states a single animal emerged from a late Paleozoic-era ocean and subsequently gave rise to all terrestrial vertebrates some 300 million years ago; and therefore, extant amphibians are each others closest relatives and all comprise a single monophyletic group. Because this primitive animal had to be amphibious in nature, it is only logical to assume it looked like either a salamander or a frog. Morphological data as well as fossil data seems to overwhelmingly support the idea that the ancestor to all terrestrial vertebrates looked like a salamander. To further answer this question, I believe we have to look at several characteristics of the three amphibian orders as well as other animals that can be utilized as out groups in a phylogenetic comparison. I also believe morphological data is no longer adequate, since we now have the ability to clone DNA, molecular data seems to be the right option to better understand the possible complex origins of amphibians. To accomplish this I have cloned the homologs to the RNA binding protein dazl from all three amphibian orders- Rana pipians (Anura), Notopthalmus viradecins (Urodele), and Typhlonectes natans (Gymnophiona), in the hopes of gaining an better understanding of the phylogenetic relationship of the three extant taxa. For out group comparison, I used the murine and zebrafish homologs to the dazl gene (already cloned by different labs) and I PCR'ed the gene from chicken (Gallus gallus) and lizard (Gekko gekko) using ovary cDNA. Again using degenerate primers, I have also cloned the dazl homolog from the primitive African lungfish (Protopterus annectans) and hope to clone it from Coelacanth (Latameria chalumne).
After obtaining the dazl sequences from each of the aforementioned species, I hope to do three things: First, run dazl-probed tissue northerns to show tissue specificity in each species. The gene dazl encodes a protein which is part of a large family of RNA binding molecules, therefore it is essential that I demonstrate this gene is specific to the germ cells. Once I do this I will perform in situ hybridizations with lungfish and cacealian eggs utilizing each species specific dazl clone as a template. This assay should provide me with the spatial expression of the gene within the egg. If there is a localization in the vegetal hemisphere, I will assume that the method of germ cell formation in these species is analogous with that of lower protostomes. Then questioning the mechanisms of gene migration will be of great importance. I believe this question can be addressed by cloning and sequencing the 3' UTR's (untranslated regions) from the dazl gene via PCR. These UTR's are paramount to localization events in Drosophila and Xenopus; this domain binds specific proteins that target the RNA's to the vegetal hemisphere. Salamanders do not have this extensive UTR region, and therefore do not have localized germ plasm. Finally, I would like to sequence the conserved region of the dazl gene from as many related taxa. Having the sequences from both primitive and derived species will allow me to develop a phylogeny based on this novel gene.
I am really excited about my Ph.D. project. I feel I can significantly contribute to a very important biological question with the work that I am undertaking. It seems very unusual, in the biological sciences today, to be able to answer a general question such as this, and even more unusual to be able to bridge disciplines (molecular biology, development, and evolution) in an attempt to elucidate embryological origins. I hope to complete this work as well as completely characterize the Axolotl vasa gene in the next eighteen months. I also hope to lower my golf handicap to single digits, compete in an ironman distance triathlon, Run low 8's in my car, and marry Mira Sorvino (I will probably stick with Science... I got a little carried away). So anyway, when I'm not working hard in the lab (which is seldom if ever), I love to race my supercharged Pontiac, play golf and coach the best class 'B' softball team in Tallahassee. I also like to ride my bicycle and watch any sports; BTW, I have the top 10 college football predictions for the upcoming year.
10. The Colorado Buffalos, after
thrashing the Neuheisal-led Huskies 55-3, will win the 1999 national championship
beating a strong Florida State team 28-24 in the most thrilling sugar bowl
to date.
9. The University of Florida's head
coach Steve "mini-Richard" Spurrier will bitch and moan about "they hit
our quarterback late", and "those FSU players play dirty" when FSU goes
to the swamp and annihilates the Gators.
8. Beano Cook will grow another
chin, and once again predict a PSU-Notre Dame national championship game,
and like usual, he will be wrong.
7. Coach Corso will say "not so
fast my friend" 22 times this season breaking the old record of 18 set
in 1997, and Fowler, tired of being #2 will kick Herbstreet in the ass
so hard that even Craig James will feel it.
6. All of the teams in the new "Mountain
West" conference will suck as bad as they did when they were in the WAC
(it takes more then a name change to make it in Division 1 guys).
5. The lone FSU receiver that is
not injured, or academically ineligible, or on probation for drug
use, or in jail, will win the Heisman trophy in 1999.
4. Bobby Bowden, Joe Paterno, Lou
Holtz, LaVelle Edwards, and Howard Schnellenberger will all get together
and discuss the birth of Christ..... from first had experience.
3. Two University of Florida Cheerleaders
are on the top of the Leon County Civic Center. Which will come down
first.... The Civic Center.
2. The University of Colorado, after
recruiting a female kicker, will see the error of their ways and send the
girl to the Home Economics department where she can learn to cook and clean
like she should.
1. And finally, Even though all
of these predictions will come to pass, Bristol University School of Football
still won't accept me.
"When I am king, I will put an end to air pollution. All of my subjects will drive around in ethanol powered golf carts. I however, will tool around town in 1973 El camino with a ram air induction, a 510 cubic inch stroked hemi big block, 2-650 cfm Holley double pumper carbs, open headers and a 'no fat chicks' license plate bracket......Silence......"
- The man show 1999