Page 90 - Abstract book - TJSSF-2020

Thailand – Japan Student Science Fair 2020 (TJ-SSF 2020)
“Seeding Innovations through Fostering Thailand – Japan Youth Friendship”

A Study on the Luminous Ability of Vargula Hilgendorfii Luciferin

Kanon Kitazono , Chika Goto , Ito Murakami , Isoda Yuki and Ezumi Yuto
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Advisor: Yuki Kutsunugi
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Hiroshima University High School
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Abstract
We have been studying Vargula Hilgendorfii, or the sea firefly, which is a tiny sea creature that emits
beautiful blue light. Our purpose is to find an effective method to maintain their luminescence for an
extended period of time without losing the luminescence intensity. To achieve this goal, we have set
two sub-goals. The first is to identify the optimum conditions for Vargula Hilgendorfii to emit
light. They emit light when their Vargula Hilgendorfii Luciferin (substrate) and Vargula Hilgendorfii
Luciferase (enzyme) are released in the sea and the substrate is oxidized by the oxygen in the sea water,
catalyzed by luciferase. Previous studies have found that the optimum water temperature for the
reaction is 4℃. It is also known that they emit stronger light in a water with the pH of 7.8 than in a
water with the pH of 6.0. In our study, we attempt to find the optimum combination of the temperature
and the pH of the water. The second sub-goal is to quantify the luminescence intensity more
easily. Previous studies used the luminometer or photometer to quantify the intensity, but they are
available to us because of their expensiveness. Instead, we have been trying to establish another method
that uses an ordinary digital camera and a computer software called Makali'i, which is widely used in
the field of astronomy. So far, we have succeeded in the quantification. We are now trying to clarify
the effects of water temperature on the luminescence time and intensity. We also plan to study the
effects of the pH of water on the luminescence time and intensity. In the end, we will compare the
results we have gained with our new quantification method with those gained by the luminometer and
verify the reliability of our method.

Keywords: Vargula Hilgendorfii, luminescence, optimum condition, quantification,

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