Image depicting glial cells in mammalian brain


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The Department of Biology focuses on teaching and research in four primary areas:

Cell and Developmental Biology

Our Cell and Developmental Biology group studies a set of very diverse problems, but they have an underlying theme based on understanding the molecular machinery that endows cells with the ability to assume different sets of properties or phenotypes and thus carry out very distinct roles in the organism. Furthermore, cells change their properties many times during the transition from a single fertilized cell to the thousands and even billions of cells the make up the adult organism. And they do all this in concert with surrounding cells, moving and changing in a pattern that is constant from one individual to the next and changes very slowly over evolutionary time. Cell and developmental biologists address how cells receive information from their environment (including other cells), how they translate that information into one of thousands of different potential responses through differential activation of genes and finally how the proteins encoded by these genes are assembled into molecular machines that run the activity centers of the cells. Addressing these basic questions involves many different approaches and techniques, and equally challenging, requires the integration of multitudes of independent observations and experiments into a coherent picture of cell function and development.


Evolutionary biologists study the "continuity of life" on earth. They strive to explain through careful observation and experiment the history of all of biodiversity, living and extinct, interwoven with the history of the earth. This grand endeavor will ultimately reveal the origins of life, how species are related, and how the geological and climatic history of the earth has influenced the changing patterns of biodiversity. To fully reconstruct this historical framework will require information from many diverse fields. Reconstruction, however, will allow new insights into problems that profoundly affect our quality of life and our very existence, from the loss of biodiversity and conservation to the role that human activity plays in modifying the ongoing evolution of all species. At the core of evolution are changes in the genetic material that occur over time; sometimes these changes are lost but when the change gives rise to a trait that is useful to the organism it is passed to the next generations. Through many small steps, each favored by the small utility it brings to the organism, large changes accrue that ultimately give rise to new and dramatic features - the eye seems to be the "feature" most often referred to in popular readings. On an every day basis we see "directed" evolution in action in the breeding of new plant crops and new varieties of animals. In the wild it is much more difficult to see, but not impossible as careful studies of changes in animal and plant populations in restricted environments, such as the Galapagos Islands, have shown. Our group of evolutionary biologists work at several levels. Some are studying the differences in DNA sequence between organisms that help us to understand the origin and relatedness of different species. Others are unraveling the molecular basis and history of differences in organization and architecture of DNA in chromosomes between closely related species. And finally, still others are investigating how different organisms have evolved the unique traits that give rise to interdependencies such as parasitism and mutualism.


We are all aware that DNA contains the genetic code or blueprint for each organism. Among asexually reproducing organisms, such as bacteria and yeast, the entire complement of DNA is copied and during cell division is transmitted to each of the two daughter cells. Such organisms give rise to clones, a population of cells with identical DNA. Among sexually reproducing organisms which have two copies of each gene, each offspring receives half of its DNA from each parent, but which copy of each gene we get is not predictable. That is why we never know exactly what our children will look like or behave like. But geneticists do not yet know the details of how this is accomplished, nor do we fully understand the how the genetic information is translated into the proteins that make up the molecular machinery of the cell. Our genetics group studies every aspect of the molecular machinery that is essential to carry out these processes in a variety of organisms. The reason that so many different organisms are used is that each has some unique advantage that allows experimental access to one or more aspect of these processes. Yeast is used to study the details of DNA replication during both mitosis and meiosis (the reduction divisions that give rise to germ cells and the memorization nightmare of all high school and college biology students). The fruit fly, because of its short generation time, has classically been used to study the transmission of genetic traits from one generation to the next and is still a favored organism for studying the genetic basis for development and behavior. Arabadopsis, a plant related to mustard, and the small freshwater aquarium Zebrafish, are being used to study the genetic basis of development and organ formation. Genetics has been profoundly changed by determination of the complete DNA sequences for each of these popular and experimentally tractable model organisms - and many others. This means that we can correlate changes in phenotype (the appearance of the organism) with changes in specific genes and ultimately understand the role of each gene and its product in the development and physiology of an organism.


Our neurobiology group focuses on cellular and molecular analysis of the nervous system, with a particular emphasis on the formation and function of connections between neurons. Each neuron in the nervous system connects with hundreds to thousands of other neurons through long axons, which are principally for output, and shorter dendrites, which are primarily for inputs. The contacts, or synapses, are highly complex multifunctional yet modifiable structures that transmit information. Synapses also change with time, depending on patterns of neural activity. We know that all people have the same senses and that we all perceive and react similarly to simple physical stimuli in our environment. However, we also know that peoples' responses to more complex situations are not identical; we all possess different memories and often act differently according to our different past experiences. Sadly, we also know that disease or disability can adversely affect our perceptions, behavior or memory. All this is reflected in the connectivity among neurons. The general patterns of connections are highly stereotyped, largely the same from one individual to the next, as are the trajectories and branching patterns of the axons and dendrites of each type of neuron. Yet the number, position, structure, and function of connections differ in detail among individuals. Neurological diseases and trauma destroy or alter neural connections and often kill the neurons themselves. The emphasis of the neurobiologists in our department is the molecular machinery that underlies the formation of these patterned connections during development and their function in the mature nervous system. We are also concerned with the dynamic changes in these connections, which appear to be the cellular basis of learning and memory. These are challenging problems in that they involve unraveling the molecular details of the nervous system - the most complex system in the known universe! However, solving these problems has great rewards in the basic understanding of our own behavior and how it can be affected by experience or by disease.