I am a Cypriot graduate student in the Lauder Lab. My research is fueled by my interest in evolutionary processeses especially those that have led to the vertebrate diversity that has existed throughout time. I have a special fondness for mechanics and I am able to integrate that with evolutionary studies by focusing on the functional morphology and development of organismal tissues. Specifically, I am interested in the effects of the mechanical environment an organism grows in on the development of its connective and skeletal tissues. I am currently working with zebrafish to test some basic hypotheses but hope to move to a comparative approach for my future work.

Curriculum Vitae

Publications

Other Interests

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Routine turns in larval zebrafish raised in high viscosity

Larval zebrafish interact with their physical environment while their locomotor system is still developing, both behavior and anatomy. Do they receive any cues from their mechanical environment as part of their normal development of this system? To explore this question I have raised zebrafish, from hatching until 5 days post fertilization, in increased viscosity water. I then filmed the larvae performing routine turns in the medium they were raised in. The results showed that zebrafish control their turning in stages and not as a single behavior. Furthermore, the angle at the end of stage 1 was constant in all the viscosity treatments while the final angle at the end of the turn became smaller at higher viscosity.

 

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Ontogeny of Zebrafish Locomotion

During my first year at Harvard I have collected data on the ontogeny of routine turning in zebrafish, a part of the animal's food searhing behavior. This is a first step in describing and partially quantifying the mechanical environment of the zebrafish in early ontogeny (5 days post fertilization). Images of the fish performing routine turns were captured at 1000 fps for fish ranging in size from 0.4 to 2.0 cm (FL). The images were analyzed using DPIV software with the PIV algorithm applied to the light image of the animal instead of laser-illuminated particles in the water. From the resulting vector matrices the following kinematic variables were collected: maximum fin velocity during a turn in absolute values and relative to the body, angular velocity of the head, maximum and final angle of the turn and turn duration.

We plotted log-transformed variables against long-body length to describe the growth trends of the kinematics. Some variables changed linearly whereas others showed a biphasic rate change with a transition point when the fish are approximately 1cm long. This is a time of major morpological changes such as ossification of axial and fin bones, complete development of fin musculature and enclosure of the lateral line in canals.

Danos, N. and Lauder, G. V. (2007). The ontogeny of fin function during routine turns in zebrafish Danio rerio. J. Exp. Biol. 210, 3374-3386.

Inside JEB commentary by Blackburn, L. (2007). TURNING PERFORMANCE IN GROWING ZEBRAFISH, vol. 210, pp. iii.

 

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Morphology and Material Properties of Eel Skin

My M.S. work involved describing the material properties and locomotory behavior of skin during locomotion in aquatic salamanders and fish. This project was part of a larger NSF-funded research program to model the complex 3-dimensional contractions of segmented muscles and how these lead to lateral bending in swimming animals. Recently a mathematical model created by Manny Azizi and my M.S. advisor, Beth Brainerd, in collaboration with Gary Gillis (Azizi et al, 2002) described the biomechanical interactions between the muscle segments, the connective tissue sheets that separate them and the vertebral column in the aquatic salamander Siren lacertina. Experimental observations made by Azizi et al. (2002) indicate, however, that there is at least one element in the existing model that is unaccounted for. Even though the skin’s properties have not been incorporated into any locomotion models this as well as other experimental and theoretical studies strongly suggest that the skin may be this missing element. The locomotory role of skin poses an interesting question in the study of functional morphology because there seems to be a compromise between the multiple functional requirements on this tissue: it has been postulated to act as an exotendon and modulates body stiffness, while at the same time it may allows for maximum strain amplification in the myomeres during contraction.

As part of this study I described the interactions between the myoseptal tendons, skin and red muscle outlining the possilbe force transmisison pathways. From the morphological data collected it seems unlikely that the skin comes under tension from the myoseptal tendons or the red muscles.

Danos, N., Fisch, N. and Gemballa, S. (2008). The musculotendinous system of an anguilliform swimmer: Muscles, myosepta, dermis, and their interconnections in Anguilla rostrata. J. Morph. 269, 29-44.

Scanning Electron Micrograph of eel skin showing alternating layers of parallel fibers and different types of transverse fibers that connect the myosepta to the skin.