Joan Ruderman

Joan Ruderman originally came to the MBL in 1974 as a postdoctoral student enrolled in the annual Embryology course (MBL, 2014). She would come back for the next 41 summers to research, teach courses, and eventually serve as director. She also played a pivotal role in the discovery of cyclin by Tim Hunt in 1982.

In 1978, Ruderman was working as faculty at the Harvard Medical School in the Department of Anatomy and each summer she would bring several students to the MBL to conduct research. In the summer of 1978, Ruderman was also co-teaching the Embryology course with Tom Humphries.

Ruderman worked primarily with surf clam (Spisula solidissima) oocytes, or clam eggs. Clam oocytes are good to conduct developmental research on because a single female clam can produce three hundred to four hundred million eggs at one time, leaving researchers with a lot of material. Clam oocytes are arrested at Gap 2 in the cell cycle - the point in the cell cycle where the cell has increased significantly in size and the DNA has replicated, but has not yet begun to divide (Jackson, 2008: 200). After the oocytes are fertilized, mitosis begins, and the cells divide.

Ruderman used clam oocytes to study the proteins involved in cell division. Clam eggs, once they are fertilized, become clam embryos and those embryos undergo unequal cleavage, or division. Cleavage is a cellular process whereby the cells of an embryo undergo rapid division. In many species, the resulting cells are exact copies of one another, but in clams and many other Spiralia (including molluscs and annelids), the initial division of one cell into two and two cells into four produces four unequal sized cells. Those cells - named A, B, C, and D - develop into different parts of the clam. A and B cells develop into the clam’s skin and nervous system and C and D develop into the clam’s gut and organs. The fates of those cells is determined at the embryonic stage, and Ruderman hypothesized that proteins may be behind the eventual fates of those cells (Ruderman interview, 6/5).

In order to determine if that was true, Ruderman and her graduate student Eric Rosenthal attempted to take two cell clam embryos and separate the two cells. They then wanted to test the two cells for different proteins to determine which were conserved across cells and which differed. However, Ruderman and her student found it difficult to separate the cells without damaging them and therefore began looking at a different phenomena (Ruderman interview, 6/5). They looked at the different proteins produced in activated or fertilized clam eggs and inactivated or unfertilized clam eggs. They found that within eight to ten minutes, the proteins produced by the unfertilized clam eggs completely switched to a new set of proteins in the fertilized clam eggs. To Ruderman, the speed at which the proteins switched indicated that the switch was translational. In cells, proteins are produced through a series of steps. The gene for a particular protein is first transcribed or copied by messenger RNA (mRNA). The mRNA then carries that information into the cytoplasm of the cell where another cellular molecule, a ribosome, reads the genetic information and translates it for transfer RNA (tRNA), which then begins assembling the protein based on the received genetic instructions. Transcription, the process of taking the genetic information from the DNA into the cytoplasm of the cell and then producing proteins from it takes significantly longer than translation. The speed of production of the new cellular proteins, in Ruderman’s eyes, required that the process be translational. The confirmation of that, however, did not come until the next summer with the help of Tim Hunt.

Suggested citation
Abboud, Alexis. 2015. "Cyclins at the MBL". MBL History Project digital exhibit. http://history.archives.mbl.edu/exploring/exhibits/cyclins-mbl
Bibliography

What are Cyclins?

Early Work with Cyclins

Tim Hunt and His Discovery of Cyclin

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Cyclins and Genetics

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