The Ayme-Southgate Lab
PROJECTIN: A SCAFFOLD FOR MYOFIBRIL ASSEMBLY IN DROSOPHILA
Agnes J. Ayme-Southgate
Ph.D.,
University of Geneva, Switzerland, 1985
Associate Professor of Biology
Department of Biology
College of Charleston
66 George Street
Charleston, SC 29424
Office: Rita Liddy Hollings Science Center, Rm 218B
Email: southgatea@cofc.edu
Phone: 843-953-6544
Fax: 843-953-5453
Web: Personal site
The research goal of Dr. Agnes Ayme-Southgate is to understand the formation of myofibril in the Drosophila model system and in particular the protein interactions involved.
Current Research
The structure of striated muscles is highly conserved throughout evolution; correlating with a significant conservation of the main myofibrillar proteins. One common feature is the presence of a third filament responsible for muscle elasticity. In Drosophila Indirect Flight Muscles (IFM), these filaments are called the connecting or C-filaments. This filament is responsible for the elasticity and resting stiffness that are involved with the physiological process of stretch activation. This mechanism allows for multiple muscle contractions for each nerve impulse, and therefore the rapid contraction of asynchronous flight muscles leading to the high wing beat of some insects. In insects, the current model for C-filaments implicates 2 proteins, projectin and kettin. Projectin is an extremely large protein at ~1 MgDa, composed of 39 repeating Ig and FnIII domains. Projectin also contains two unique sequences: a kinase domain at the COOH-terminus and a PEVK elastic sequence at the NH2-terminus The PEVK-like sequence is probably located within the I-band
Some of the studies underway in Dr. Ayme-Southgate’s laboratory are aimed at a better understanding of projectin’s elastic domain, including an identification of the amino acid sequence, its position along the sarcomere, and its evolution in various insects. They have created Drosophila transgenic flies expressing various GFP-projectin fusions. The localization of the GFP-tag, and therefore of the associated projectin domain, is analyzed using immunofluorescence microscopy of muscles during various developmental stages. Stretch studies on isolated flight myofibrils are used to identify the elastic domain. BLAST and other software are used to retrieve orthologs of Drosophila projectin in several insect species. These orthologs are analyzed for exon-intron splicing by RT-PCR and for domain structure using CLUSTAL and other software. We are also adressing projectin involvement during stretch-activation through an RNAi approach.
Lab Students
Current and Past Lab Members (click photos to enlarge)
Danielle Adler (’07):
Danielle is a Biology major who has been working in the lab since the
Fall of 2005. She has been working on the identification
of projectin's elastic domain. Initial data were presented at the National
Drosophila conference (March 2006) and Danielle presented at the CofC
Poster Day 2006. She plans to graduate in May 2007.
William Hartley (’06):
William is a Biology major, graduating in the Fall of 2006 and currently
applying to graduate school. He has worked on inhibition
of projectin by RNAi in the lab and recently addressed the question "Is
projectin essential for flight?" He has been active in the lab since
the Fall of 2005 and he presented a
poster at the CofC
Poster Day 2006.
Catherine Kramp (’07):
Catherine is a Biology major, graduating in the May of 2007 and currently
applying to medical schools. She has been active in the lab since
the Fall of 2005. She presented a poster at the CofC
Poster Day 2006 related to "Characterization of projectin elastic
domain in bee." She also contributed to a
poster with preliminary data which were presented at the National Drosophila conference in March of 2006.
Arthur Veloso (’06):
Arthur graduated in the Spring of 2006 and is now attending graduate
school as a Master’s candidate in Marine Biology at the CofC. Arthur
was active in the lab in the Fall of 2005 and Spring of 2006, working
on the Effect of actin mutations on interactions for the GFP fusions.
He contributed to a poster
[PDF] on Projectin Assembly presented at the National Drosophila conference
(March 06).
Jacqueline Roper (’06):
Jacqueline worked in the lab during the Summer of 2006. She is currently
aplying to medical and nursing schools. While in the lab she contributed
to work on "Cloning and expression of fusion proteins for the PEVK
domain."