Carlos Taboada

In the lab, we work at the intersection of biochemistry, biology, optics, and evolution. We investigate non-model amphibians that exhibit remarkable optical traits such as whole-body transparency, high infrared reflectance, and near-infrared fluorescence. To study these phenomena, we integrate theoretical and experimental approaches at the interface of organismal biology, protein science, chemical biology, and physiology.

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Evolutionary biochemistry and functional diversification of colored proteins

Hundreds of frog species exhibit a leaf-like green coloration. We have identified at least one group of proteins that carry the pigment biliverdin in their blood, lymph, and interstitial fluid. The use of plasmatic proteins to create color is a convergent trait in amphibians, having evolved independently multiple times. In the lab, we discover, identify, and physically characterize new proteins with amphibian-colored properties and investigate the molecular mechanisms that finely tune the colors they produce. To achieve this, we combine field and laboratory approaches to locate species of interest, purify and sequence their proteins, express them physically, and apply evolutionary biochemistry methods to understand the evolutionary changes in the protein landscape that produce the colors we observe in extant frogs, enabling them to efficiently camouflage in the canopy.

Light perception and color changes

Arboreal frogs sleep in various locations within the vegetation, exposing them to different light environments. Amphibians can often modulate their coloration, seemingly as a physiological adaptation to these changing light conditions. Some of these color changes involve complex physiological processes that alter or co-opt multiple biochemical pathways. We investigate how frogs sense their environment and modify their physiology in response to specific wavelengths of light.

Metabolism and transparency

How can glassfrogs and other transparent frogs achieve transparency as an extreme form of camouflage? We found that glassfrogs maintain their transparency by concealing most of their red blood cells inside their livers. This temporary deprivation of the primary vertebrate oxygen carrier would normally impair oxygen delivery to meet metabolic demands. As a result, glassfrogs must rely either on non-oxidative metabolism, alternative oxygen carriers, or highly efficient oxygen diffusion mechanisms through their tissues. In the lab, we investigate these mechanisms using a variety of behavioral, biochemical, and physical approaches.

Anticoagulants and transparency

Packing red blood cells inside the liver for half of the day while they sleep leads to blood stasis, a condition that in other vertebrates, including humans, is known to promote vaso-occlusive events. In sleeping glassfrogs, red blood cells occupy most of the hepatic sinusoids, but surprisingly, they do not form a pathological clot, which presumably makes glassfrogs tolerant to thrombosis. Interestingly, the extrinsic coagulation pathway remains functional, allowing glassfrogs to form clots in response to external trauma such as wounds. This ability to prevent excessive clotting while preserving functional extrinsic pathways is difficult to achieve in clinical settings, where conventional anticoagulant therapies often carry the risk of excessive bleeding. In the lab, we investigate the mechanisms underlying these remarkable hematological adaptations of glassfrogs.

Biological mirrors

Transparent frogs typically coat their internal organs and peritonea with mirror-like tissues. These tissues reflect most of the incident light due to the high scattering properties of large quantities of organic crystals deposited in their cells. In the lab, we investigate various aspects of these phenomena, from the biochemical pathways responsible for the accumulation of the metabolites that form the crystals, to the active roles these crystals play in amplifying colors and regulating metabolic functions.