Overview

About Kamei Lab.

-Aiming to elucidate the biological significance of heat and temperature-

Temperature is one of the important parameters for living organisms, and living organisms inhabit various environmental temperatures. However, the temperature on the nanoscale has not been discussed so far. Recently, nano-scale thermometers utilizing fluorescent proteins and dyes were developed by some research groups, and they reported heterogeneity of temperature in the microenvironment of living cells, respectively. Our group dives into a new research field, biothermology, through investigating the nature of temperature for the living organisms from nano to macro.

RMC Professor KAMEI, Yasuhiro

Overview

-Temperature biology-

Fig.1.Image of heat shock stress response mechanism of cells and laser irradiation to single cells in vivo

Fig.2. Infrared laser irradiation temperature measurement microscope system

 High-speed acquisition of two-wavelength fluorescence images with two sCMOS cameras enables quick observation of temperature rise during infrared laser irradiation.

Many organisms have a heat shock response mechanism that protects cells from heat stress (Fig. 1, left). Laboratory for Biothermology is focusing on heat shock transcription factor (HSF) 1 as one means for clarifying the connection between temperature and organisms, and is conducting research to clarify its temperature sensing mechanism and activation kinetics.

Currently, we are working on the elucidation of the molecular mechanism of HSF1 activation from multiple biological species such as medaka, medaka-related species, flounder, and frog from a biological perspective.

In addition, it is necessary to know the thermophysical properties of biological materials in order to investigate the connection between temperature and living things. Therefore, we are also developing a microscope technology that can measure the temperature of target cells in vivo while heating locally. So far, we have constructed a high-speed living body temperature imaging system (Fig. 2) by applying a fluorescent protein probe (Reference 1) that can measure temperature from the ratio of fluorescence intensity of two wavelengths. Using this, we are trying to analyze thermophysical properties of biological materials.

Reference1. Nakano M, Arai Y, Kotera I, Okabe K, Kamei Y, Nagai T. (2017) Genetically encoded ratiometric fluorescent thermometer with wide range and rapid response. PLoS One, 12(2), e0172344.

-Local gene expression technology and its improvement-

Figure 3. Local temperature changes due to infrared irradiation (temporal change and three-dimensional temperature distribution)

The temperature near the focal point rises sharply by infrared laser irradiation and is kept constant during irradiation (left). In the depth direction, a dozen or more areas are heated (right). 

By utilizing the heat shock response and inserting the target gene downstream of the heat shock promoter and introducing it into an organism, it becomes possible to induce the expression of the target gene by heat shock. Laboratory for Biothermology possesses technology that can induce (manipulate) the expression of target genes only by target cells by focusing and irradiating infrared laser with a microscope to heat single cells in the body (Fig. 1, right). 

This method (IR-LEGO method: Reference 4) is applied to model organisms such as medaka, zebrafish, and Arabidopsis. Many collaborative studies (references 2 and 3) with researchers outside of Japan are carried out using this technology. On the other hand, the current IR-LEGO has some difficulties. In order to overcome it, we are applying the above research to improve IR-LEGO.

Reference 2. Okuyama T, Yokoi S, Abe H, Isoe Y, Suehiro Y, Imada H, Tanaka M, Kawasaki T, Yuba S, Taniguchi Y, Kamei Y, Okubo K, Shimada A, Naruse K, Takeda H, Oka Y, Kubo T and Takeuchi H. (2014) A neural mechanism underlying mating preferences for familiar individuals in medaka fish. Science, 343, 91-94.

Reference 3. Shimada A, Kawasishi T, Kaneko T, Yoshihara H, Yano T, Inohaya K, Kinoshita M, Kamei Y, Tamura K and Takeda H. (2013) Trunk exoskeleton in teleosts is mesodermal in origin. Nat. Commun., 4, 1639.

Reference 4. Kamei Y, Suzuki M, Watanabe K, Fujimori K, Kawasaki T, Deguchi T, Yoneda Y, Todo T, Takagi S, Funatsu T and Yuba S. (2009) Infrared laser-mediated gene induction in targeted single cells in vivo. Nat. Methods 6, 79-81.(Pubmed)