Mikhail Navashin

Mikhail Sergeevich Navashin (; 27 February 1896 – 28 September 1973) was a Soviet cytologist and cytogeneticist known for his work on plant chromosomes and chromosome evolution. He was among the first researchers to demonstrate chromosomal translocations in plants and proposed a hypothesis linking translocations to changes in basic chromosome numbers during evolution. Navashin is also known for providing the first explicit cytological description of ring chromosomes in plants, reported in 1930 in species of the genus Crepis. Ring chromosomes were subsequently described in animals by Lilian Vaughan Morgan in Drosophila melanogaster and analyzed in detail in maize by Barbara McClintock in the early 1930s.

Biography

Navashin was born in Kyiv in 1896, the son of the botanist Sergei Navashin. In 1918 he graduated from the agronomy faculty of the Kyiv Polytechnic Institute.

From 1920 to 1924 he worked at the Tbilisi Polytechnic Institute. Between 1924 and 1937 he was affiliated with the Timiryazev Biological Institute in Moscow. From 1927 to 1929 he worked abroad in the laboratory of Ernest B. Babcock at the University of California, Berkeley, where he conducted cytological research on species of Crepis. Navashin came to Berkeley on an International Education Board fellowship and remained for nearly three years, earning a PhD while collaborating with Babcock on cytogenetic studies of the genus Crepis. Their collaboration culminated in a monographic treatment of the genus published in 1930.

From 1934 to 1937 Navashin served as director of the Moscow University Botanical Garden. From 1937 to 1941 he worked at the Institute of Genetics of the Academy of Sciences of the USSR. During 1941–1948 he worked at the Institute of Cytology, Histology, and Embryology of the Academy of Sciences.

From 1948 to 1969 he worked at the Komarov Botanical Institute. In 1955 he became head of the Department of Genetics and Plant Breeding at Leningrad State University. In the same year he was among the signatories of the Letter of Three Hundred, which criticized the dominance of Trofim Lysenko and Lysenkoism in Soviet biology.

In the final years of his career, from 1969 until his death in 1973, Navashin worked at the Semenov Institute of Chemical Physics of the Academy of Sciences.

He died in Moscow on 28 September 1973 and was buried at Peredelkino Cemetery. thumb

Scientific work

Navashin's research focused primarily on the cytogenetics of plants. His early work investigated chromosome morphology, hybridization, and chromosomal variation in species of Crepis. In 1930 he reported the occurrence of ring-shaped chromosomes formed when the ends of a chromosome fuse to create a closed circular structure.

Personal life

His father, Sergei Navashin was a noted botanist and cytologist who discovered double fertilization in flowering plants.

His son, Sergei Mikhailovich Navashin (1924–1998), was a microbiologist and a member of the Academy of Medical Sciences of the USSR.