Genetically encoded ratiometric fluorescent thermometer with wide range and rapid response

Area of Science:

• Biophysics
• Cell Biology
• Genetics

Background:

• Temperature is crucial for biological processes, but conventional thermometers have limitations in range and speed.
• Existing methods struggle with diverse species and lack temporal resolution for dynamic temperature monitoring.
• Understanding cellular and organismal temperature is key to studying metabolism and physiological responses.

Purpose of the Study:

• To develop a novel, genetically encoded thermometer for broad temperature range and rapid response.
• To overcome limitations of conventional thermometry in biological systems.
• To enable precise spatiotemporal temperature measurements from cellular to in vivo levels.

Main Methods:

• Engineered a genetically encoded ratiometric fluorescent temperature indicator (gTEMP) using two fluorescent proteins with distinct temperature sensitivities.
• Utilized ratiometric fluorescence to quantify temperature changes with high temporal resolution (50 ms).
• Applied gTEMP to monitor intracellular temperature dynamics and in vivo temperature in model organisms.

Main Results:

• gTEMP demonstrated a wide temperature sensitivity range (5°C to 50°C) and rapid response time.
• Successfully observed spatiotemporal temperature changes between cytoplasm and nucleus in cells.
• Quantified mitochondrial thermogenesis and monitored temperature in a medaka embryo for 15 hours.

Conclusions:

• gTEMP is a versatile tool for accurate, real-time temperature measurements in diverse biological contexts.
• Enables detailed investigation of thermal dynamics in cellular processes and whole organisms.
• Shows feasibility for in vivo thermometry across various species, advancing physiological research.