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It will mark 10 years in 2021 since the Fukushima nuclear accident.

I have been belonged to Otaki laboratory that launched “Fukushima project” two months after the accident and

became known worldwide* for the paper published in August, 2012.

This is a study of the biological effects of the accident using the pale grass blue butterfly (Zizeeria Maha).

Six years have passed since I participated in Fukushima project.

I reared thousands of them but never get tired of them.

When they flutter, the pale blue color of wing surface appears and disappears, and it holds my sight.

In this work, one year in Otaki lab. will be documented in a diary format from March 11, 2020 to March 11, 2021.

I would be happy if I could convey a little bit of ambition of the research to people who have supported Fukushima project and

share the moment of the 10th anniversary.

Scroll down for older date. 


3/11/2021: 10 years have passed since the accident. This will be the last post and I want to join my hands in prayer at the end as well as the beginning.


3/10/2021: Professor Otaki, who has led Fukushima project, in his not so tidy room. He always loves butterflies and enjoys science. I wonder how many things he has undertook that we students do not know about for the last 10 years.


3/7/2021: The pale grass blue in Fukushima is now overwintering in the larval stage and will  flutter their wings probably in early May. The image is the overwintering individual actually found in our field survey at Iwaki city, Fukushima prefecture in March 2018. It's thought that they were receiving initial exposure to more than 10 kinds of radioactive materials after March 11th, 2011, cowering beside Oxalis in this way.


3/3/2021: DNA sample extracted from the thorax of the pale grass blue collected in Fukushima and Ibaraki prefectures since 2011. They change their figures and lie in a freezer. The importance of these samples, especially at the time of the accident, cannot be explained in a few lines. The research at a gene level  is currently ongoing using dozens of generations.


2/28/2021: In the most recent paper published, we discuss the larval food plant for the first time.  Looking at the cross section of larva, the body is filled with food. The pale grass blue is a monophagous and eats only Oxalis leaves in the larval stage, so this species highly depends on Oxalis. The pale grass blue is not the only one living in radioactively contaminated environment. Without considering the ecosystem including Oxalis and nectar sources (food), spiders and frogs (predators), ants (symbionts), bees and flies (parasites), and so on, the whole picture of Fukushima never appears.


2/22/2021: The fruit of Oxalis that is food of the pale grass blue is called “Basanaigwa” meaning small banana in Okinawa dialect. It also called “Mehajicha” meaning the fruit exploding because the seeds burst vigorously when touched with a finger. Flying distance of seeds can be over 1 m. Oxalis has an astonishing number of names and more than 180 in various dialects are known nationwide.


2/18/2021: A shell casing was used to shield natural radiation for measuring radioactivity concentration. It came into steelworks as scrap from the end of the Showa period (1926-1989) to the beginning of the Heisei period (1989-2019). The military base is right there.


2/14/2021: Last night, an earthquake with a maximum intensity of 6 upper on the Japanese sale of 7 (equal to a magnitude 7.3) hit off the coast of Fukushima. I remembered spending time in 2011, taking a picture until the cherry blossoms fell. Yesterday, today, tomorrow, counting one, two, three pictures, eases my anxiety. February, it is the blooming season of Taiwan cherry in Okinawa.


2/12/2021: He is one of the members who started Fukushima project and senior remaining in the lab. We chased hundreds of butterflies, searched for several overwintering larvae, and collected tens of thousands of food plant leaves. I rely on him and lean from him, so I am who I am today. He also bakes sweet.


2/9/2021: Imaging plate is one of ways to visualize radiation. The image is natural radiation on my palm for five minutes. I cannot help but stare at them when I think of them coming from space or inside the earth. What is invisible is always far beyond our expectation.


2/1/2021: Romerillo thrives in Okinawa. It can benefit and also harm humans, but  the pale grass blue like especially this flower nectar, in my opinion. At this time of the year, there are few of insects and it's quiet around the flowers.


1/27/2021: Even if they are born on the same day from the same parents and reared in the same container feeding the same food, some grow fast and small, and others do slow and large. Some are male, and others are female. Some have morphological abnormality, and others do not. Some die early, and others survive.


1/20/2021: Okinawa prefecture’s own state of emergency was declared today, but there is no change in university life, as before. I weigh Oxalis leaves to the nearest 0.000 mg.


1/15/2021: One of supporters remodeled the storage room into the laboratory six years ago. Lead blocks are arranged inside tanks filled with water, and radiation source is placed behind the blocks. For the safety of experimenters, the outside of the tank is shielded to natural radiation level. Although not currently in use, two external irradiation experiments were carried out between 2015-2019.


1/10/2021: January is the coldest month in Okinawa, but it still exceeds 15 degrees Celsius during the day. Dandelions are underfoot. I miss the white breath in the winter air. The image is Oxalis having pink flowers in this season (Oxalis corymbosa). It's one of the six species of Oxalis native to Japan and introduced during the Edo period (1600-1868). The  pale grass blue doesn't eat this Oxalis (see 2/10).


1/5/2021: Eclosion is a life threatening event and its timing is delicately controlled by multiple hormones. Even under the normal rearing conditions, some individuals die in the pupal stage or process of eclosion, but this number increases with radiation exposure. The image is a dead pupa from Fukushima city, Fukushima prefecture, in 2011. While the effects of radiation exposure appear in morphological changes, it can also disrupt the balance of physiological functions such as hormones. We listen to the voice of butterflies that ended their lives without fluttering.


12/30/2020: The simple wing color pattern: black spots on a white background, makes it easy to identify abnormality and is one of reasons why the pale grass blue is suitable for research. Nevertheless, individual differences do exist and can be difficult to distinguish from abnormalities. In such a case, confirmation by several people is necessary, but it doesn't take long to come to an agreement.


12/23/2020Two of the third year students who newly joined the lab in this October are working on Fukushima Project. He is one of them and from Fukushima. He was an elementary school student at the time of the accident. How will he go back for 10 years during his graduation research with the pale grass blue coming from his hometown?


12/18/2020Although maple and ginkgo trees aren't found in Okinawa, autumn leaves can be seen. Walking around the school on a sunny day, Chinese tallow tree shimmers in the blue sky.   


12/11/2020Radiation workers are required to undergo a health checkup every six months. Height, weight, chest measurement, eye test, hearing test, blood pressure measurement, medical examination, electrocardiogram, blood test, and urine test. The words on the medical interview sheet sent chills down my spine for a moment and pull myself together after “Fukushima” becomes a daily occurrence.


12/7/2020For rearing experiments to see the transgenerational effects, eggs were obtained from the field sampled females in contaminated areas. More than 10,000 individuals were reared during three years, 2011-2013 and the image is a few of them.  Just imagining a huge amount of work: collecting leaves for food everyday, recording the growth process, and searching morphological abnormalities, makes me dizzy and out of breath. The senior experimenter was graduated but he is still chasing butterflies for his job.


11/30/2020Oxalis leaves are only food of the pale grass blue but a troublesome weed for humans. Its collection is like playing a cat and mouse game with grass cutting work, and recently we have been loosing. In the evening, my junior and I looked around the school for the clustering spots.


11/24/2020A larva of the pale grass blue looks cute from a distance, but they actually have a face like this. What looks like a raised eye is antenna with a  projection in the center. Each of the grains on outer of both antennae is a monocular eye detecting the light. In an adult, they form a visual structure called a compound eye, which consists of smaller individual eyes, ommatidia. Scale: 1.00 mm.


11/20/2020I won’t tell the details, but ingestional toxicity experiment is currently going on. Various compounds will be added to artificial diet instead of fresh Oxalis leaves and the effects on development will be seen.


11/17/2020Life during a rearing experiment revolves around the butterfly time. Students are busy with class, teaching practice, dissertation, job hunting, studying for entrance exam, part time job, internship, but in between, they clean up larval droppings and feed them.


11/13/2020I pin a butterfly as a hobby. Some I caught on my way to school, some I begged from graduating seniors, some I got from juniors after a rearing experiment, some came into the front door or bathroom of my flat, and some I brought back from the field survey…


11/6/2020Using a digital microscope, the morphological abnormalities of the pale grass blue are observed in detail. The image on the computer screen shows a specimen from Hirono town, Fukushima prefecture, about 20 km south of the nuclear power plant. The offspring of the field sampled individuals in 2011 and reared under the unexposed condition, 99.33% of them were lethal or morphologically abnormal. “Something is going on”


11/1/2020: In prewar Okinawa, there was a custom for brides to wear a ring called “Husai-Binagi” and return home the day after their wedding ceremony. Each of seven auspicious designs has own meaning and the second from the right, butterfly, is “a messenger from heaven” (Restored by Ms. Kazuko Aragaki in 2006: Collection of Fujukan, University of the Ryukyus)


10/28/2020On the anniversary of my senior’s passing, I open her research notebook. Each day blows through the pages like a gust of wind. Compared to hers, my days are like a breeze.


10/22/2020The package of the pale grass blue was arrived from Fukushima. Only three individuals were females out of 30 but there is no sex difference in the field population. Males are more active in flight, so that they are easily found by people. The morphological abnormality rate, etc. were calculated for the current record. For nine and a half years since the accident, we have received countless packages like this from supporters.


10/13/2020DNA was extracted from six year old specimens of the pale grass blue, and the specific sequence was amplified. When the regent that binds to double stranded DNA and emits light under UV is added, DNA is visualized. The rows are the number of samples. The same height of light shows that the same sequence is successfully obtained for all 10 specimens.


10/6/2020Opening the door of the laboratory breathlessly, there was a junior student in the midday light and silence. She has been working on Fukushima project for three years and will graduate next spring.


10/2/2020The pale grass blue metamorphoses into egg, 1st to 4th instar larva, prepupa, pupa and adult. During the larval stage, they're monophagous, eating only Oxalis leaves, and thin skin remains in the eat marks of the 1st instar larvae. Humans have also been involved with Oxalis for long. It's used in Chinese medicine for skin disease, polishing Buddhist altars, one of the five major family crests and also appears in “The Pillow Book” in the year about 1000.


9/28/2020At radioisotope center of the university, the exposure limit is set at 20 mSv/year. Eating and drinking are prohibited and medical checkup is required every six months. Returning to Fukushima, they're guaranteed a “normal life” with the same dose. Being protected by the law let us realize that Fukushima is a special land.


9/25/2020The wing length, growth rate, eaten area on leaves by single larva per day, nutrient components of host plant… life phenomena are fragmented into data and numbers are orderly lined up in Excel.


9/17/2020Radiation workers are required to wear a personal dosimeter. After the accident, elementary school students in my howetown hang the same one on their school bags. Sometimes, figures of them run through my mind.


9/7/2020The fury of the typhoon can be seen all around the campus. Many of us might have been secretly watching over the Taiwan cherry, which booms in different colors in February.


9/3/2020A lace pattern appears on the surface of an egg of the pale grass blue when magnified 200 times. Sitting in front of the microscope and adjusting the white balance, magnification, light intensity, and focus one by one, another world opens up.


8/27/2020Greenery grows and the population of the pale grass blue increases outside in this season. They lay eggs less than 1 mm on the underside of Oxalis leaves. Even in emergency, there is the usual summer scenery at my feet.


8/25/2020γ ray measurement with the germanium semiconductor detector is ongoing. There is a peak of cesium-137 at 662 keV.  What “Fukushima (Oxalis leaves)” tells directly becomes the starting point for research.


8/20/2020Liquid nitrogen (-196℃) is supplied to keep the germanium semiconductor detector running and a full container is too heavy to carry by one person. To measure radioactivity, some physical work is needed.


8/16/2020The experiment on how much soil adheres to the body surface of larva. Roll one by one on the soil. In a time like this, I feel close to this little creature.


8/13/2020Germanium semiconductor detector for γ-ray measurement. Move eight lead blocks which is approximately 11 kg each with your index finger and center the sample inside. Once you get the hang of it, it’s nothing for small woman like me.


8/6/2020Preparation for radioactivity measurement of Oxalis leaves, the pale grass blue’s food, collected last month in Fukushima. After dry, crush and put in a special columnar container.


8/1/2020From today to 15th, Okinawa prefecture-specific state of emergency is announced. The first infected person is found at the university and only graduate students and above can enter the campus. Chased by time, I carefully measure the wing length.


7/30/2020In a rearing experiment, I put individual number and keep a record of the date of egg collection, pupation date, eclosion date, sex, morphological abnormality, death date and wing length. Wing length of dried specimen is measured recently and wings are less than 30 mm when spread. Wings don’t shrink due to drying and it’s used as the evaluation of body size commonly in butterfly.


7/27/2020Egg collection of the pale grass blue. Set host plant, Oxalis, planted pots and creeping daisy for nectar, and release several females in an aquarium. When I turn off the light in lab., going back home, it appears impressively.


7/24/2020On the silent holiday under the coronavirus situation, U.S. military aircraft roars in the campus. For some reason, many fly in this morning.


7/20/2020Speciments are reviewed as a fourth year graduation research. One generation turns in one month for the pale grass blue, so it’s 47-48th generation now from the accident. The image is the individual with a bent wing collected in Fukushima, 2011.


7/14/2020On the last day of the survey, we visited Science museum of atomic energy in Ibaraki prefecture which is next to Fukushima. There is one of the largest cloud chambers in the world. Could we change if we can see radiation?


7/11/2020: Namie town. Small copper flies in bushes where it still shows over 3.50 μSv/h ground dose. Okinawa is out of the distribution area, but we come across them often in Fukushima. Its cuteness captures eyes of all of us for a moment.


7/10/2020A truck carries bags of contaminated soil. Everyday life in Fukushima hangs from the window of our rental car.


7/9/2020Getting in Fukushima prefecture for field survey, the scent of long rain and the deep purple of hydrangea, the feeling of hometown gradually comes back.


7/1/2020All grades are permitted admission for their research today. Campus stays quiet and there is only mechanical sounds of some analyzer. The image is tubes for measuring DNA concentration.


6/26/2020From senior to junior, the research is entrusted and continues.


6/23/2020Okinawa memorial day. “Scented, scented  shell ginger flower  booms forever  flower heart  unchanging life  unchanging heart  summer of homeland” (Shell ginger flower: music and lyrics by Yutaka Umisedo)


6/12/2020Rainy season ends 28 days earlier than last year. Students are still restricted to enter the campus at “Level 2”


6/8/2020Lab. meeting takes place on every Monday. Today, the first meeting was held remotely and everyone gathered beyond the screen for the fist time in a few months.


6/3/2020The pale grass blue is still few outside in this year. Instead, plains cupid that feeds on Japanese sago palm flies around. Although the distribution is expanding northward, it’s not found in Tohoku region including Fukushima. Similar to the pale grass blue, but once you get used to it, you won’t mistake.


5/29/2020In our lab., butterflies are reared not only for Fukushima Project. Common mormon has been begun to collect eggs earlier than the pale grass blue. It lives south of the Tokara islands and isn’t rare in Okinawa. I stop at its presence different from that of lycaenidae.


5/22/2020Doctor and above are conditionally permitted to enter the campus from yesterday. Around this time, it’s covered in fog.


5/2/2020Home study continues. Organize numbers, apply to statistics, plot them, see the result and imagine what appears. Facing computer, repeat this all day.


4/23/2020University closure is announced from day after tomorrow. I hurry to weight radioactively contaminated soil to bring back as mush as data possible.


4/21/2020From the new semester to the begging of rainy season, it’s the best time to start rearing experiment. It’s still empty rack in this year.


4/17/2020Something that would be wiped away normally still remains in deserted campus.


4/10/2020Unintentionally, I remember last year’s today. On April 10th, 2019, we were creeping and finding the pale grass blue overwintering in Rifu town, Miyagi prefecture (next to Fukushima). The following day, it snowed as cherry blossom was coming out.


4/9/2020Home study is encouraged to prevent coronavirus ​infection, so the new semester raised the curtain quietly today. Two postdocs, two masters, four fourth years, all students did't meet each other and new attendance board showed many “Home”


3/24/2020The graduation ceremony was canceled and the diploma awarding was held with only people concerned. In our lab., two of the four graduates including me completed Fukushima Project.


3/23/2020: Predators, symbionts, parasites and flowers fed on, all live in the continuity of ecosystem. Investigation into food of the pale grass blue has just started. The image is frozen samples of host plant, Oxalis, leaves.


3/11/2020Mayflower blooming in March in Okinawa. For more than ten thousand years, we have offered flowers.


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