About This Project

An animal's ability to adapt to short- and long-term changes in temperature is crucial for its survival. Lizards are ectotherms that rely on their environment to regulate body temperature, so they experience a wide range of temperatures. We don't yet know how lizard cells remain viable across extreme temperatures, especially within the brain. We are studying the regulation of brain lipids (i.e., fats) in biological membranes to understand how lizards adapt to and live in extreme environments.

Ask the Scientists

What is the context of this research?

Lipids are the building blocks of cell membranes that influence the membrane's fluidity, or the extent of disorder in the lipid bilayer. We know that cells can regulate the semi-fluid state of membranes in response to changes in temperature.

Senensky (1973) described this process (called homeoviscous adaptation) in which cells at higher temperatures have more saturated lipids. This allows cells to maintain a rigid membrane because saturated lipids are tightly attracted to each other. Membrane fluidity is also governed by unsaturated lipids (Murata & Los, 1997). Decreasing temperature produces kinks in lipid tails that decrease lipid attraction, allowing unsaturated lipids to spread out and prevent the membrane from becoming too rigid.

Our question: does this process occur in lizard brains?

What is the significance of this project?

The interaction between brain lipids and environmental temperature is an important component of how animals adapt to rapidly changing environments. Further, our study provides a molecular model for how adaptation occurs at the cellular level. In fact, cell membrane fluidity affects the function of many proteins in the bilayer that influence cellular activity (Spector & Yorek, 1985).

Studying the biochemical mechanisms of lipid adaptation within the well-known group of Caribbean anole lizards also provides a physiological mechanism for how species evolved to occupy a particular niche within their habitat. Lipid adaptation may also contribute to the variation in behaviors exhibited across species, especially if the lipid profile of the brain evolved to suit a particular environment.

What are the goals of the project?

Our first goal is to use mass spectroscopy analysis of cell membrane extracts from whole brains to describe lipid composition as a function of temperature. We predict that lizards in warmer environments will have a larger ratio of saturated:unsaturated lipids. We collected brain tissues during a field study of 7 Puerto Rican Anolis species that occur in habitats of varying temperature, and during a lab experiment to directly determine how temperature influences brain lipids.

The second goal is to culture primary astrocytes at warm and cool temperatures to directly quantify plasma membrane fluidity by fluorescent polarization. We expect cells at 35°C to exhibit greater fluidity from those cultured at 28°C.

All procedures approved by Trinity's Animal Research Committee (protocol #MJ050615).