Dr. Leslie Babonis is a post-doctoral researcher in the Martindale Lab where she works studying the development and origins of cnidocytes, the specialized stinging cells for which the cnidarians (sea anemones, corals, jellyfish) are named.
For Dr. Leslie Babonis, joining the Martindale Lab in June 2011 as a post-doctoral researcher was a sort of homecoming. After graduating from Punahou School ('99), Dr. Babonis chose to leave Hawai'i to pursue her interest in marine science at the University of Miami, where she enrolled in the Marine Science/Biology program. She continued her studies at the University of Florida, where she received her Ph.D. While her move back to Hawai'i was as straightforward as a flight from Jacksonville to Honolulu, her research journey was more circuitous. Her path of research experiences took her through the fields of oceanography, physiology, ecology, and evolutionary developmental biology, the latter eventually leading her home to Hawai'i to work with Dr. Mark Martindale.
"My path through research has been a tumultuous one", explained Dr. Babonis. "As a high school student I took oceanography and marine biology courses and participated in the Waikiki Aquarium's Blue Water Marine laboratory summer program. These were my first experiences with marine research and really got me interested in the field."
As a sophomore at the University of Miami, Dr. Babonis enrolled as a student in the Sea Education Association's SEAmester Program, where she had her first opportunity to carry out an independent research project. During her time in the SEAmester Program, she designed and carried out a field-based project aimed at understanding the physiochemical factors affecting the depth of the euphotic zone a various locations throughout the Caribbean Sea.
"It was a great experience to be in charge of my own project and really helped foster my interest in independent research," said Dr. Babonis.
After graduating from the University of Miami with a Bachelor's degree in Biology, Dr. Babonis spent a year working as a Conservation Intern at Biscayne National Park in Homestead, FL, where she assisted in a large-scale water quality monitoring program aimed at assessing the effects of land use on coastal freshwater runoff.
"During my time with the Park Service, I spent a lot of hours in the hypersaline coastal regions of Biscayne Bay and began to wonder about the diversity of animals that were tolerant of such extreme abiotic conditions," recalls Dr. Babonis. "These observations led me to the University of Florida where I began a PhD project aimed at understanding the evolution of marine habitat use in snakes."
The primary focus of her dissertation research was to understand the relationship between cellular identity and physiological function in the secretory epithelia of marine snake cranial glands and other osmoregulatory tissues. Although the majority of her work was aimed at understanding the functional differences between specialized salt-secreting glands and unspecialized seromucous glands, over time she became deeply interested in understanding the mechanisms underlying the development of specialized salt-secreting glands.
"It has been hypothesized that the evolution of a specialized salt gland results from co-option of a seromucous gland already in place", explained Dr. Babonis. "As I began to think about this hypothesized co-option, I began to wonder about homology at the level of the cell type. This level of inquiry ultimately inspired me to seek out a postdoctoral position aimed at understanding how cells acquire their identity, landing me here at Kewalo!"
Since joining the Martindale lab, Dr. Babonis has been working to understand the mechanisms that regulate the acquisition of cell identity in cnidocytes, the stinging cells for which the cnidarians (sea anemones, corals, jellyfish) are named. To this end, Dr. Babonis has been developing techniques for the selected deletion and/or overexpression of cnidocytes in the starlet sea anemone, Nematostella vectensis. Perhaps the most fruitful of these endeavors so far has been the development of the laser ablation system to induce cnidocyte firing in specific anatomical locations.
"With the use of this tool, I have been working to characterize the temporal markers of cnidocyte development in Nematostella during replacement of the cnidocytes at the tentacle tip", said Dr. Babonis. "Ultimately, I hope to identify the upstream regulators of cnidocyte cell identity by comparing the process of cnidocyte replacement, following firing, and during the development of cnidocytes in early embryos".
In parallel to her cnidocyte research, Dr. Babonis has recently begun working on a project aimed at understanding the potential function of the nematosomes from which the genus Nematostella draws its name. Originally described merely as "multicellular motile bodies", nematosomes appear to be aggregations of various cell types that circulate through the body cavity, including the lumen of the tentacles.
"Although the function of nematosomes has yet to be identified, the conspicuous presence of mature cnidocytes of all three types found in Nematostella epidermis suggests a possible functional role in prey immobilization or digestion, and provides a unique opportunity to understand the developmental origin of cnidocytes", explained Dr. Babonis.
Additionally, Dr. Babonis has been working to characterize the cell types populating the tentacle tips (i.e., to identify those cells interspersed among the cnidocytes in the tentacle epithelium) and the mesenteries (which are both populated by cnidocytes and are thought to be the tissue of origin for the nematosomes) using a combination of scanning electron microscopy and transmission electron microscopy at the Biological Electron Microscopy Facility on the UH Manoa main campus.
"I love being back here in Hawai'i doing research at one of the most ideally situated marine labs in the world. Where else can you look up from a microscope to see beautiful Diamond Head out the window?" said Dr. Babonis.
Laser-induced firing of cnidocytes in the tentacle tip of N. vectensis. The laser target is visible as a bright white spot. (Video by Leslie Babonis).
Time-lapse of a tentacle tip following firing (25 min). Fired cnidocytes and adjacent cells in the tentacle epithelium delaminate from the basement membrane following firing. (Video by Leslie Babonis).
Isolated nematosome. The ability to induce cnidocyte firing using the laser is one indication that these multicellular bodies are composed of mature cnidocytes. (Video by Leslie Babonis).