Katsuma Dan
Encyclopedia
Japanese people
The are an ethnic group originating in the Japanese archipelago and are the predominant ethnic group of Japan. Worldwide, approximately 130 million people are of Japanese descent; of these, approximately 127 million are residents of Japan. People of Japanese ancestry who live in other countries...
embryologist and cell biologist
Biologist
A biologist is a scientist devoted to and producing results in biology through the study of life. Typically biologists study organisms and their relationship to their environment. Biologists involved in basic research attempt to discover underlying mechanisms that govern how organisms work...
. He was born in 1905, the youngest son of Baron Dan Takuma
Dan Takuma
was a Japanese businessman who was Director-General of Mitsui, one of the leading Japanese zaibatsu . He was a graduate of Massachusetts Institute of Technology and was married to the younger sister of statesman Kaneko Kentarō....
, president of the Mitsui Gomei Kaisha Corporation. Takuma Dan was educated in the United States, graduating from MIT in 1878. He was one of the first foreign students to be educated at MIT and later, as president of the Japan Steel Works, he initiated and maintained close research ties with The Institute.
After receiving his undergraduate degree in Japan, Katsuma Dan also came to the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
where he studied embryology with Prof. L.V. Heilbrunn at the University of Pennsylvania
University of Pennsylvania
The University of Pennsylvania is a private, Ivy League university located in Philadelphia, Pennsylvania, United States. Penn is the fourth-oldest institution of higher education in the United States,Penn is the fourth-oldest using the founding dates claimed by each institution...
. In addition Dan worked and studied at the Marine Biological Laboratory
Marine Biological Laboratory
The Marine Biological Laboratory is an international center for research and education in biology, biomedicine and ecology. Founded in 1888, the MBL is the oldest independent marine laboratory in the Americas, taking advantage of a coastal setting in the Cape Cod village of Woods Hole, Massachusetts...
at Woods Hole (MBL
MBL
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) from 1931-1934, and later in 1936. It was here that he met his future wife (and longtime scientific collaborator) Jean M. Clark (1910-1978). Clark, who was also a student of Heilbrunn's, studied fertilization in marine invertebrates. The couple raised five children. They also maintained lasting ties to the MBL
MBL
MBL can refer to:* Mobile, used in Cisco documentation* Free Bolivia Movement , a political party in Bolivia* Macquarie Bank, used on the ASX to refer to the bank's shares...
and returned often in later years as summer researchers and lecturers in embryology.
In March 1932, while Dan was studying at the MBL
MBL
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, his father was assassinated in Japan by ultra-nationalist radicals in the 'League of Blood Incident
League of Blood Incident
was a 1932 assassination plot in Japan in which extremists targeted wealthy businessmen and liberal politicians. The group chose twenty victims but succeeded in killing only two: former Finance Minister and head of the Rikken Minseito, Junnosuke Inoue, and Director-General of Mitsui Holding...
'. Katsuma Dan returned to Japan
Japan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...
in the late 1930s and worked at the Misaki Marine Biological Station in Morioso Bay. He and his students maintained a remarkable degree of scientific productivity during World War II. His spirit is reflected in a letter written after the war to a friend in the United States: “...ducking under bombs was not so bad. Rather it was a great excitement. Hide and seek at the expense of your life can't help being exciting. There was, however, an awful side to it too.” Near the end of the war the Japanese Navy took over the Misaki Marine Station and converted it into a base for miniature submarines. Although displaced, Dan and his students set up a crude laboratory nearby and continued their work. At the end of the war Dan posted a hand-written note on the door of Misaki, addressed to advancing America forces, in which he said: “... you can destroy the weapons and the war instruments but save the civil equipments [sic] for the Japanese students. When you are through with your job here notify to the university [sic] and let us come back to our scientific home.” The note was signed, “The last one to go.” The obvious humanity and the mention of American marine biological laboratories appealed to a US Naval officer who passed the note on to the MBL
MBL
MBL can refer to:* Mobile, used in Cisco documentation* Free Bolivia Movement , a political party in Bolivia* Macquarie Bank, used on the ASX to refer to the bank's shares...
. It was later published in Time Magazine under the headline, “Appeal to the Goths”.
Dan's scientific work focused on using marine invertebrates as model organisms to study fundamental questions in cell biology
Cell biology
Cell biology is a scientific discipline that studies cells – their physiological properties, their structure, the organelles they contain, interactions with their environment, their life cycle, division and death. This is done both on a microscopic and molecular level...
and embryonic development. He and his students focused on direct observation of cell behavior using light microscopy and discovered many of the fundamental aspects of fertilization, development
Developmental biology
Developmental biology is the study of the process by which organisms grow and develop. Modern developmental biology studies the genetic control of cell growth, differentiation and "morphogenesis", which is the process that gives rise to tissues, organs and anatomy.- Related fields of study...
, and morphogenesis
Morphogenesis
Morphogenesis , is the biological process that causes an organism to develop its shape...
(e.g., Dan and Okazaki, 1956). To settle a long-standing debate over the existence of the mitotic spindle
Mitotic spindle
In cell biology, the spindle fibers are the structure that separates the chromosomes into the daughter cells during cell division. It is part of the cytoskeleton in eukaryotic cells...
, he encouraged his student, Shinya Inoue, to construct polarized light microscopes and look for evidence of organized polymer
Polymer
A polymer is a large molecule composed of repeating structural units. These subunits are typically connected by covalent chemical bonds...
networks in living cells. And, together with Daniel Mazia
Daniel Mazia
Daniel Mazia was an American cell biologist, best known for his 1951 research with Katsuma Dan that isolated the cell structures responsible for mitosis....
, he was the first to isolate the mitotic apparatus and subject it to biochemical study. This work demonstrated conclusively the existence of the mitotic spindle
Mitotic spindle
In cell biology, the spindle fibers are the structure that separates the chromosomes into the daughter cells during cell division. It is part of the cytoskeleton in eukaryotic cells...
and initiated the modern biochemical study of mitosis
Mitosis
Mitosis is the process by which a eukaryotic cell separates the chromosomes in its cell nucleus into two identical sets, in two separate nuclei. It is generally followed immediately by cytokinesis, which divides the nuclei, cytoplasm, organelles and cell membrane into two cells containing roughly...
.
Dan and his students also developed methods for measuring small, local movements of the cell surface during division. This enabled detailed, quantitative studies of the process of cell cleavage (cytokinesis
Cytokinesis
Cytokinesis is the process in which the cytoplasm of a single eukaryotic cell is divided to form two daughter cells. It usually initiates during the late stages of mitosis, and sometimes meiosis, splitting a binucleate cell in two, to ensure that chromosome number is maintained from one generation...
). Based on this work, Dan proposed the novel idea that cell cleavage is driven directly by elongation of the mitotic spindle
Mitotic spindle
In cell biology, the spindle fibers are the structure that separates the chromosomes into the daughter cells during cell division. It is part of the cytoskeleton in eukaryotic cells...
. That is, the spindle itself attaches to the cell surface via 'astral rays' (microtubules) and physically draws in the cleavage furrow
Cleavage furrow
In cell biology, the cleavage furrow is the indentation that begins the process of cleavage, by which animal and some algal cells undergo cytokinesis. The same proteins responsible for muscle contraction, actin and myosin begin the process of forming the cleavage furrow. This can only happen in...
(Dan, 1943). Subsequent work indicated that cleavage is actually driven by contraction of an actin
Actin
Actin is a globular, roughly 42-kDa moonlighting protein found in all eukaryotic cells where it may be present at concentrations of over 100 μM. It is also one of the most highly-conserved proteins, differing by no more than 20% in species as diverse as algae and humans...
filament network in the cortex rather than by expansion of the spindle but this idea was the forerunner of the current view of cytokinesis
Cytokinesis
Cytokinesis is the process in which the cytoplasm of a single eukaryotic cell is divided to form two daughter cells. It usually initiates during the late stages of mitosis, and sometimes meiosis, splitting a binucleate cell in two, to ensure that chromosome number is maintained from one generation...
, in which interaction of spindle microtubules with the cell cortex
Cortex (anatomy)
In anatomy and zoology the cortex is the outermost layer of an organ. Organs with well-defined cortical layers include kidneys, adrenal glands, ovaries, the thymus, and portions of the brain, including the cerebral cortex, the most well-known of all cortices.The cerebellar cortex is the thin gray...
determines the position of the cleavage furrow
Cleavage furrow
In cell biology, the cleavage furrow is the indentation that begins the process of cleavage, by which animal and some algal cells undergo cytokinesis. The same proteins responsible for muscle contraction, actin and myosin begin the process of forming the cleavage furrow. This can only happen in...
.
Katsuma Dan was professor of zoology
Zoology
Zoology |zoölogy]]), is the branch of biology that relates to the animal kingdom, including the structure, embryology, evolution, classification, habits, and distribution of all animals, both living and extinct...
at the Tokyo Metropolitan University
Tokyo Metropolitan University
Tokyo Metropolitan University is one of the largest public universities in Japan...
from 1949-1968. He also served as president of the university from 1964 until his retirement in 1972. Dan was president of both the Zoological Society of Japan
Japan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...
and the Japanese Society of Developmental biologists. In 1976 he received the Second Order Imperial Medal, and in 1987 he received the Emperor's Award for Cultural Merit. A fellowship honoring Katsuma and Jean Dan was established in 1979 for cultural exchange between the United States and Japan.
Katsuma Dan died in 1996 in Osaka
Osaka
is a city in the Kansai region of Japan's main island of Honshu, a designated city under the Local Autonomy Law, the capital city of Osaka Prefecture and also the biggest part of Keihanshin area, which is represented by three major cities of Japan, Kyoto, Osaka and Kobe...
, Japan
Japan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...
, at the age of 91.
Sources
- Obituary, Falmouth Enterprise, May 24, 1996.
- Schneider, M. (Personal Communication) MBL/WHOI Archives, Woods Hole MA.
- Inoue, S. (1989) Achievements of Professor Katsuma Dan. MBL/WHOI Archives, Woods Hole MA.
- Ewick, D. 2003. Untitled note. Japanisme, Orientalism, Modernism: An archive of Japan in English-language verse.