Brookhaven Biology Research History

A damaging sun
Brookhaven biologist Richard Setlow holds a beaker of backcross hybrids of Xiphophorus fish, a species used to demostrate how exposure to sunlight is related to skin caner.

Clues in flowers
Beginning in 1958, Brookhaven researchers pioneered the use of Tradescantia flowers as one of the first tools in cell mutation studies. These flowers were used because their petals can be made to change color in response to mutagens such as chemicals or radiation.

Gene breakthrough
In 1992, Brookhaven biologists pioneered a new way to decipher DNA structure. They've since decoded the genome of the bacterium that causes Lyme disease, which will aid in the search for new vaccines.

Tritiated Thymidine

In 1956, Brookhaven researchers discovered a new way to study DNA by attaching the radioisotope tritium to thymidine, one of the building blocks of DNA.

Tritiated thymidine was first used in an investigation of chromosomes, the carriers of double-stranded DNA (left). In 1957, Brookhaven biologists tested the Watson and Crick model of the molecular structure of DNA by using tritiated thymadine to produce a photographic image of DNA synthesis in plant roots. The astonishing results provided the first evidence that Watson and Crick's model of DNA replication operated at the level of individual chromosomes. This experiment also provided the first microscopic identification of "sister chromatid exchange," a cellular phenomenon now extensively used to study genetic damage caused by exposure to toxic substances.

Tritiated thymidine also proved useful in studies of cell migration and growth throughout the body. Following initial studies with mice, the first human clinical studies were done in 1957. This research showed how long it takes for labeled bone marrow cells to appear in peripheral blood. Later studies focused on cell proliferation in various cancers and in the gastrointestinal tract. Within a few months after this work was presented by Brookhaven researchers at a 1958 meeting, tritiated thymidine was in great demand all over the world. Today, it is used in many different immunological tests and has become a standard for studies in cell proliferation.

UV Light and Cancer 

DNA is present in the nucleus of every cell in the human body. When a cell divides, its DNA copies itself so the genetic message remains intact. However, the genetic message sometimes becomes flawed because the DNA has been damaged. One of the constituents of sunlight, ultraviolet (UV) light can cause several kinds of chemical changes in DNA.

In 1979, Brookhaven biologists conducted experiments in which human skin cells were exposed to several small doses of UV light, rather than one single dose, to mimic what happens to humans who receive multiple, small sunlight exposures. This was the first time human cells were shown to be transformed to a pre-malignant stage by UV exposure. Later experiments by Brookhaven biologist Richard Setlow used backcross hybrids of a species of fish called Xiphophorus to show that malignant melinoma, a deadly skin cancer, could be induced by both UV-A and UV-B sunlight. Previously, it was believed that only UV-B exposure could induce such cancers.

Virus mechanisms

Perhaps someday every species' DNA sequence will be a matter of record. But in 1982, this was far from the case. That's when scientists at Brookhaven finished determining the sequence of the DNA of the virus T7, the longest DNA sequence then known. In all, 39,936 base pairs were counted and identified. The genetic map was correlated with T7's protein production, which led to a detailed understanding of how such viruses control their own replication. At left, Brookhaven biologists William Studier (seated) and John Dunn check the results of analysis of protein production using T7 RNA polymerase.