|Awards||HHMI Professor, Searle Scholar|
|Thesis||Genetic analysis of the yeast microtubule cytoskeleton (1988)|
|Doctoral advisor||David Botstein|
|Other academic advisors||Marc Kirschner|
Tim Stearns (born 1961 in Huntington, New York) is an American biologist and university administrator, and is the Dean of Graduate and Postgraduate Studies, Vice President of Education, and Head of Laboratory at The Rockefeller University.Stearns was formerly the Frank Lee and Carol Hall Professor in the Department of Biology at Stanford University, with appointments in the Department of Genetics and the Cancer Center in the Stanford Medical School. Stearns served as chair of the Department of Biology at Stanford as well as Acting Dean of Research and Senior Associate Vice Provost of Research. Stearns is an HHMI Professor, and is a member of JASON, a scientific advisory group. He has served on the editorial boards of The Journal of Cell Biology , Genetics and Molecular Biology of the Cell .
Stearns received his B.S. in genetics from Cornell University and did his undergraduate thesis work in the lab of Tom Fox on nuclear control of mitochondrial function in yeast. He received his Ph.D. in biology from the Massachusetts Institute of Technology. His Ph.D. advisor at MIT was David Botstein, and the title of his thesis was "Genetic analysis of the yeast microtubule cytoskeleton." Stearns' thesis identified exceptions to the genetic complementation test that were useful for defining genetic interactions and for the first time used the term "synthetic lethality" in the modern sense of two non-lethal mutations resulting in lethality in the double mutant.Stearns credits Botstein with instilling in him a commitment to teaching, and the belief that teaching and research go hand-in-hand.
Stearns is known for his work on problems in cell biology and developmental biology, with a focus on the structure and function of the centrosome and cilium of eukaryotic cells. He was a Helen Hay Whitney postdoctoral fellow with Marc Kirschner at UCSF, where he published work on gamma-tubulinand in vitro reconstitution of the centrosome. Stearns has been a faculty member in the Department of Biology at Stanford since 1993. His major research accomplishments include the identification and characterization of new members of the tubulin superfamily of proteins, elucidation of mechanisms of centrosome duplication, and identification of properties of the primary cilium.
Stearns has also been active in undergraduate and graduate education, being named an HHMI Professor in 2002,and has chaired the Education committees of the American Society for Cell Biology and the Genetics Society of America. He created a pre-grad program at Stanford to train the next generation of leaders in biology research through close interaction with faculty members in course work, research and advising. Stearns taught the Yeast Genetics course at Cold Spring Harbor Laboratory, and has also taught laboratory workshops in South Africa, Chile, Ghana, and Tanzania.
Stearns is an advisor to the US government on science and technology matters. He was a member of the Defense Science Study Group, and is a current member of JASON,an independent scientific advisory group to the US that provides expertise on problems related to national security.
Stearns and his wife reside in NYC. They previously lived near Stanford University and tended a fruit tree orchardoriginally planted by John Hensill, former dean of Natural Sciences at San Francisco State University, and a founder of the Redwood City Farmers Market. Stearns is an accomplished musician, and student of American traditional music and early jazz.
In cell biology a centriole is a cylindrical organelle composed mainly of a protein called tubulin. Centrioles are found in most eukaryotic cells, but are not present in conifers (Pinophyta), flowering plants (angiosperms) and most fungi, and are only present in the male gametes of charophytes, bryophytes, seedless vascular plants, cycads, and Ginkgo. A bound pair of centrioles, surrounded by a highly ordered mass of dense material, called the pericentriolar material (PCM), makes up a structure called a centrosome.
Microtubules are polymers of tubulin that form part of the cytoskeleton and provide structure and shape to eukaryotic cells. Microtubules can be as long as 50 micrometres, as wide as 23 to 27 nm and have an inner diameter between 11 and 15 nm. They are formed by the polymerization of a dimer of two globular proteins, alpha and beta tubulin into protofilaments that can then associate laterally to form a hollow tube, the microtubule. The most common form of a microtubule consists of 13 protofilaments in the tubular arrangement.
In cell biology, the centrosome is an organelle that serves as the main microtubule organizing center (MTOC) of the animal cell, as well as a regulator of cell-cycle progression. The centrosome provides structure for the cell. The centrosome is thought to have evolved only in the metazoan lineage of eukaryotic cells. Fungi and plants lack centrosomes and therefore use other structures to organize their microtubules. Although the centrosome has a key role in efficient mitosis in animal cells, it is not essential in certain fly and flatworm species.
The microtubule-organizing center (MTOC) is a structure found in eukaryotic cells from which microtubules emerge. MTOCs have two main functions: the organization of eukaryotic flagella and cilia and the organization of the mitotic and meiotic spindle apparatus, which separate the chromosomes during cell division. The MTOC is a major site of microtubule nucleation and can be visualized in cells by immunohistochemical detection of γ-tubulin. The morphological characteristics of MTOCs vary between the different phyla and kingdoms. In animals, the two most important types of MTOCs are 1) the basal bodies associated with cilia and flagella and 2) the centrosome associated with spindle formation.
A basal body is a protein structure found at the base of a eukaryotic undulipodium. The basal body was named by Theodor Wilhelm Engelmann in 1880 It is formed from a centriole and several additional protein structures, and is, essentially, a modified centriole. The basal body serves as a nucleation site for the growth of the axoneme microtubules. Centrioles, from which basal bodies are derived, act as anchoring sites for proteins that in turn anchor microtubules, and are known as the microtubule organizing center (MTOC). These microtubules provide structure and facilitate movement of vesicles and organelles within many eukaryotic cells.
Timothy John Mitchison is a cell biologist and systems biologist and Hasib Sabbagh Professor of Systems Biology at Harvard Medical School in the United States. He is known for his discovery, with Marc Kirschner, of dynamic instability in microtubules, for studies of the mechanism of cell division, and for contributions to chemical biology.
In cell biology, microtubule nucleation is the event that initiates de novo formation of microtubules (MTs). These filaments of the cytoskeleton typically form through polymerization of α- and β-tubulin dimers, the basic building blocks of the microtubule, which initially interact to nucleate a seed from which the filament elongates.
David Moore Glover is a British geneticist and Research Professor of Biology and Biological Engineering at the California Institute of Technology. He served as Balfour Professor of Genetics at the University of Cambridge, a Wellcome Trust investigator in the Department of Genetics at the University of Cambridge, and Fellow of Fitzwilliam College, Cambridge. He serves as the first editor-in-chief of the open-access journal Open Biology published by the Royal Society.
Gamma-tubulin complex component 3 is a protein that in humans is encoded by the TUBGCP3 gene. It is part of the gamma tubulin complex, which required for microtubule nucleation at the centrosome.
Neural precursor cell expressed, developmentally down-regulated 1, also known as Nedd1, is a human gene and encodes the protein NEDD1.
Pericentriolar material is a highly structured, dense mass of protein which makes up the part of the animal centrosome that surrounds the two centrioles. The PCM contains proteins responsible for microtubule nucleation and anchoring including γ-tubulin, pericentrin and ninein.
Centrosomal protein of 192 kDa, also known as Cep192, is a protein that in humans is encoded by the CEP192 gene. It is the homolog of the C. elegans and D. melanogaster gene SPD-2.
Centrosomal protein of 164 kDa, also known as CEP164, is a protein that in humans is encoded by the CEP164 gene. Its function appears two be twofold: CEP164 is required for primary cilium formation. Furthermore, it is an important component in the response to DNA damage by UV light.
Centrosomal protein of 152 kDa, also known as Cep152, is a protein that in humans is encoded by the CEP152 gene. It is the ortholog of the Drosophila melanogaster gene asterless (asl) and both are required for centriole duplication.
Centrosomes are the major microtubule organizing centers (MTOC) in mammalian cells. Failure of centrosome regulation can cause mistakes in chromosome segregation and is associated with aneuploidy. A centrosome is composed of two orthogonal cylindrical protein assemblies, called centrioles, which are surrounded by a protein dense amorphous cloud of pericentriolar material (PCM). The PCM is essential for nucleation and organization of microtubules. The centrosome cycle is important to ensure that daughter cells receive a centrosome after cell division. As the cell cycle progresses, the centrosome undergoes a series of morphological and functional changes. Initiation of the centrosome cycle occurs early in the cell cycle in order to have two centrosomes by the time mitosis occurs.
Ciliogenesis is defined as the building of the cell's antenna or extracellular fluid mediation mechanism. It includes the assembly and disassembly of the cilia during the cell cycle. Cilia are important organelles of cells and are involved in numerous activities such as cell signaling, processing developmental signals, and directing the flow of fluids such as mucus over and around cells. Due to the importance of these cell processes, defects in ciliogenesis can lead to numerous human diseases related to non-functioning cilia. Ciliogenesis may also play a role in the development of left/right handedness in humans.
Tubulin, gamma 1 is a protein in humans that is encoded by the TUBG1 gene. This gene encodes a member of the tubulin superfamily. The encoded protein localizes to the centrosome where it binds to microtubules as part of a complex referred to as the gamma-tubulin ring complex. The protein mediates microtubule nucleation and is required for microtubule formation and progression of the cell cycle.
Tubulin, epsilon 1 is a protein in humans that is encoded by the TUBE1 gene. This gene encodes a member of the tubulin superfamily. This protein localizes to the centriolar sub-distal appendages that are associated with the older of the two centrioles after centrosome duplication. This protein plays a central role in organization of the microtubules during centriole duplication
Sfi1 homolog, spindle assembly associated (yeast) is a protein that in humans is encoded by the SFI1 gene. It localizes to the centriole, and its S. pombe ortholog has been shown to be involved in spindle pole body duplication. SFI1 forms a complex with centrin 2.
Don W. Cleveland is an American cancer biologist and neurobiologist.