In memoriam


We have received the sad news that Prof Dr. Adajapalam Natarajan has passed away on August 28th. Our thoughts are with his family. To honor the memory of this dear friend, highly appreciated colleague and outstanding scientist, who received the EEMS award in 1990, our former president Leon Mullenders has summarized some of Natarajan’s activities and achievements.

Prof Dr. Adajapalam Natarajan

On August 28th 2017 Prof Natarajan passed away at the age of 89 years. Natarajan or ‘ Nat ‘ like most colleagues and friends used to know and to call him, grown up in a traditional family in the South of India and followed his passion namely to become scientist to study and understand chromosomes. In 1958 a prestigious Rockerfeller Foundation Fellowship brought him to the Brookhaven National Laboratory USA to study ionizing radiation effects in plants and to the Stockholm University to get a PhD in Radiation Biology. He joined the University of Leiden in 1975 to start his research group at the Department of Radiation Genetics and Chemical Mutagenesis. His work was devoted to cytogenetic research to study and understand chromosomes in mammalian cells. He played a leading role in understanding the impact of ionizing radiation and chemical mutagens on the integrity of chromosomes i.e. the induction of chromosomal alterations. His basic research was directed towards the mechanisms of formation of chromosomal alterations particularly the roles of DNA strand breaks and various repair pathways. In his work he exploited the availability of defined mutant mammalian cells and mouse strains as well as enzymatic approaches to induce defined DNA double strand breaks in order elucidate the mechanisms of DNA strand break repair at the chromosomal level. In this way his research group dissected together with other researchers, the role of homologous recombination and end-joining in the formation of chromosomal alterations. The development of FISH (fluorescence in situ hybridization) and specific probes increased the sensitivity of chromosome analyses spectacularly. The combination of the abovementioned tools and the innovative imaging facilities in Leiden put Natarajan at the forefront of cytogenetic research. His laboratory was a hotspot for young students, postdocs, senior scientists etc. from all parts of the world to take advantages of his mentorship, the infrastructure, new upcoming technologies for chromosome painting, scientific discussion, and surely the many parties.

Natarajan made important basic and applied contributions to environmental research as well. The growing awareness of mutagens in the environment asked for sensitive screening techniques; cytogenetics offered this sensitivity and chromosomal aberrations became a basis for genetic toxicology testing. His research focused on methodologies (e.g. in vivo aneuploidy test), biological dosimetry (Goiania radiation accident in Brazil) and populations studies (e.g arsenic) as well. He was a prominent member of the EEMS and the series of annual workshops on cytogenetics that he organized together with Prof G. Obe are famous and highly appreciated. After his retirement in 1998 he continued to follow his passion for and dedication to chromosome research as a visiting professor at the University of Tuscia in Professor Palitti’s lab in Italy. During his professional life Natarajan published almost 400 papers and received a series of awards including awards of the European and American Environmental Mutagen Societies.

His last paper appeared in October 2016 less then one year before his death. Nat has published an overview of his work entitled: ‘Reflections on a lifetime in cytogenetics’ in Mutation Research (Reviews in Mutation Research) 751,1-6 (2012).

Leon Mullenders

Professor L.H.F. Mullenders
LUMC, Department of Human Genetics
The Netherlands