Meet the 2009 Early Career Scientists.
Michael T. Laub
Massachusetts Institute of Technology
Credit: ©2009 Donna Coveney/MIT
Before scientists had ready access to microarrays to measure the activity of thousands of genes simultaneously, Michael Laub built his own as a graduate student. He wanted to dissect the genetic circuitry in the bacterium Caulobacter crescentus, so he designed the tool he needed to find hundreds of genes that ensure that the bacterium divides only when conditions are right. Laub, now at the Massachusetts Institute of Technology, has since expanded his view of how cells process information and control behavior, and he is analyzing the complete set of genes and proteins involved in cell cycle progression and other signaling pathways in Caulobacter. His goal is to determine how feedback loops and other design features link these signaling molecules in elaborate molecular circuits. He is also developing new methods for the rational rewiring of signaling pathways in bacteria.
University of Michigan
Credit: ©2009 Lin Jones/UM Photo Services
During DNA replication, the very ends of a DNA molecule are lost. To prevent erosion, chromosomes are capped with a specialized region of DNA known as a telomere, whose length shortens with each cell division. Telomeres that are too short can accelerate aging; telomeres that remain long can aid the survival of cancer cells. With so much riding on the telomere, University of Michigan structural biologist Ming Lei says that a good look at its protectors is in order, so his lab is working to reveal the exact shape of the molecules that build telomeres and keep them intact. His studies are examining telomeres themselves, as well as the enzyme that lengthens them—telomerase—and a protective protein complex called shelterin, which includes six telomere-associated proteins.
Harmit S. Malik
Fred Hutchinson Cancer Research Center
Credit: ©2009 Susie Fitzhugh
Harmit Malik sees conflicts raging within a cell's nucleus, as genes jockey for evolutionary dominance. These clashes can have a long-term impact on organisms, as they sometimes alter the function of essential genes. Malik, who is at the Fred Hutchinson Cancer Research Center, uses biochemistry and genomics to study the causes and consequences of these genetic conflicts in yeast, fruit flies, and primates. His work has offered novel explanations for host-pathogen interactions and for the evolution of structural DNA elements (centromeres) that are critical for proper cell division. For example, to explore why humans are susceptible to HIV, Malik and his colleagues resurrected an extinct retrovirus that infected chimps and gorillas, but not humans, four million years ago. Malik's research suggests that we may be vulnerable to HIV infection because our defenses evolved to fight off other viruses instead. Recently, Malik and his colleagues have shown that host proteins can evolve to defeat viral “mimicry,” providing yet another nuance to a never-ending arms race between hosts and viruses.
Joshua T. Mendell
The Johns Hopkins University School of Medicine
Credit: ©2009 Keith Weller/JHMI
The Myc gene is a powerful cancer promoter, and Joshua Mendell at the Johns Hopkins University School of Medicine has identified intriguing new details about how it works. According to Mendell's recently published work, Myc accelerates cancer by repressing numerous microRNAs, tiny snippets of RNA that inhibit gene activity. Mendell is using mouse and human cells to discover how microRNAs are regulated and how they affect cell signaling, and he has been building evidence that many microRNAs are themselves oncogenes and tumor suppressors. He plans to begin using zebrafish as a model organism to accelerate the pace of discovery in his lab. As Mendell acknowledges, the field of microRNA research is relatively new and fast-moving—those who hesitate are left behind.
Stanford University School of Medicine
Credit: ©2009 Paul Fetters
Stanford neuroscientist Tirin Moore has made major strides in understanding how the brain chooses which items to process selectively among the overwhelming number contained in a scene—in other words, how the brain “pays attention.” To aid these studies, Moore is continually developing new techniques and approaches for measuring the activity of individual neurons in specific regions of the brains of monkeys as they process visual and spatial information during attention-demanding tasks. Moore has discovered that activating neurons that control a monkey's eye movements can cause the animals to pay closer attention to visual stimuli. This work identified a region of the brain that links looking with visual perception, and has given scientists a foundation for deeper investigations of the neural circuitry of attention. Moore hopes these studies will help determine how that neural circuitry fails in people who have attention-deficit/hyperactivity disorder.
Kenneth D. Poss
Duke University Medical Center
Credit: ©2009 Bill Stagg
Developmental biologist Kenneth Poss uses zebrafish, which readily regrow amputated fins, damaged spinal cord, and injured heart muscle, to study how tissue regeneration occurs in vertebrates. When he arrived at Duke University School of Medicine in 2003, he established what is now one of the largest zebrafish facilities in the country, housing more than 60,000 fish in 4,500 tanks. Poss is developing genetic tools to learn how injury stimulates new growth and how new cells correctly integrate into tissue that is being repaired. He hopes to use findings from his zebrafish studies to encourage regeneration in mammalian tissues that cannot naturally fix themselves.
University of Chicago Medical Center
Credit: ©2009 Adam Przeworski
Having too many chromosomes, a condition called aneuploidy, is the leading cause of miscarriages and developmental disabilities, including Down syndrome. Molly Przeworski, a population geneticist at the University of Chicago, hopes that her research will one day lead to a genetic test that can tell prospective mothers and fathers whether they are at risk for producing an embryo with too many chromosomes. To get there, Przeworski will sift through the genetic profiles of thousands of individuals to search for clues to predict when meiosis, the cell-division process that creates egg and sperm cells, will go awry and produce extra chromosomes. She has already used her data analysis techniques to reveal that a crucial aspect of meiosis—the process by which parental chromosomes are shuffled—varies greatly between humans and chimps and among humans. Because this kind of chromosome reshuffling can lead to aneuploidy, Przeworski intends to find the factors that control it and understand how they differ among individuals.