In Memoriam: Dr. Donald D. Brown (1931-2023)

Professor Donald Brown, highly regarded developmental biologist at Carnegie Institution for Science, Baltimore MD, passed away 31st of May, 2023. He was 91.

Donald Brown, whose pioneering molecular biology research advanced our understanding of the fundamental nature of genes and led to early breakthroughs in genetic engineering, played a leading role in transforming biology from a primarily observational pursuit, in which researchers relied on microscopic observations of processes, to a mechanistic discipline in which investigators used novel techniques to study the interlocking functions of genes coding and cellular components. He is widely recognized for his role in spearheading and championing the ability to manipulate genes in a laboratory environment. In 1995, his group pivoted to studying the genetics underpinning the transformation of tadpoles into frogs.

Among other honors, he recieved the Society for Developmental Biology's SDB Lifetime Achievement Award in 2009 (read more here:https://www.sdbonline.org/sites/Awards/Brown-Life09.pdf). He retired in 2014.

Read the tribute to Donald Brown here on the Carnegie Science Insititute's website: https://carnegiescience.edu/donald-brown-whose-work-revealed-fundamental-nature-genes-has-died

Read In Memoriam: Dondald D. Brown (1931-2023), Halpern & Harland. Developmental Biology (2023) v.501, p.A18-A20: https://www.sciencedirect.com/science/article/pii/S0012160623001094?via=ihub

Read: Thoru Pederson Proceedings of the National Academy of Sciences, Vol. 120, No. 31 https://www.pnas.org/doi/10.1073/pnas.2310224120?ai=11u2g&ui=g66n&af=T

Read: Donald D. Brown (1931–2023) - Nature | Vol 620 | 10 August 2023 | p271

Why metamorphosis?

Metamorphosis in frogs and toads is a set of complex developmental programs controlled by thyroid hormone (TH). The pervasive and dramatic changes that occur as a tadpole turns into a frog have captured the attention of life scientists from many disciplines. For evolutionary biologists, the extent to which related organisms incorporate metamorphosis in their life cycle is of paramount interest. For specialists who study cell death, a burgeoning field of research interest, apoptosis is a major event in metamorphosis. TH can induce it in many tissues, even in whole organs. For endocrinologists, TH-induced metamorphosis is a model for the general problem of the molecular basis of TH action and the interaction of the hypothalamus, the pituitary, and the thyroid glands. However, the emphasis in the Brown laboratory was the use of amphibian metamorphosis to study complex developmental programs such as vertebrate organogenesis, which can be initiated by the simple addition of TH to the tadpole's rearing water.

A developmental program is affected through the expression of many genes, causing changes in phenotype. The traditional way to study complex programs has been to identify mutants that change the phenotype. However, Don saw that there are many important programs that one would like to study in organisms that are not suitable for traditional genetics. This list includes vertebrate organogenesis, amphibian metamorphosis, tissue and organ regeneration, changes after birth in mammals, diseased versus normal tissues, the action of hormones or drugs on their target tissues or organs, and the influence of various environmental stimuli on a particular organ.

The later that a program is expressed in the life cycle of any organism, including those suited for genetics, the more difficult it will be to use traditional genetics. An alternative approach to the analysis of complex programs utilizes molecular biological methods that isolates and identifies genes whose expression change as the programs are executed.

Professor Brown developed a strategy that is generally applicable to the analysis of complex programs, using TH induced metamorphosis in Xenopus laevis as a model, in which they identified genes that are regulated by TH in a variety of tissues and organs by hybridizing probes with micro arrays. Their first array publication is Das et al. Dev. Biol. (2006).

Donald Brown's full publication list can be found on the Xenbase Literature Tab of his profile:

https://www.xenbase.org/xenbase/community/person.do?personId=1072&method=displayProfile