Yixian Zheng’s lab has a long-standing interest in cell division. In recent years, their findings have broadened their research using animal models, to include the study of stem cells, genome organization, and lineage specification—how stem cells differentiate into their final cell forms. They use a wide range of tools, including genetics in different model organisms, cell culture, biochemistry, proteomics, and genomics.

Cell division is essential for all organisms to grow and live. During a specific time in a cell’s cycle the elongated apparatus consisting of string-like micro-tubules called the spindle is assembled to move the chromosomes into two new cells. Another structure near the cell’s nucleus, the centrosome, is important for creating the microtubules and for assembling the spindle. Researchers are trying to understand the regulation of the spindle assembly, the structure of the centrosome, and how it organizes the microtubules and participates in spindle assembly.

The scientists use the frog Xenopus for their research.  The centrosome consists of a pair of cylinder-shaped structures called centrioles, which are surrounded by a material called pericentriolar material (PCM). Microtubules arise from this PCM. The Zheng scientists discovered a ring complex containing an essential protein component of microtubules called γ -tubulin. They found that the ring complex, named γ TuRC, is essential for centrosomes to form microtubules. They also uncovered an important signaling pathway controlled by a protein made in the nucleolus called GTPase Ran that regulates multiple aspects of cell division.

To study genome organization in development and aging, they use various tools to study how genomes obtain their organization in stem cells and during development. To understand the influence of the process of the cell beginning to shape, called cell morphogenesis, on the eventual type of cell it turns into, the researchers use a technique called pre-implantation mouse embryos. The development of a pre-implanted embryo allows them to discern the first type of cell differentiation, or lineage specification, in a small number of initially similar cells independent of any influence from other tissues. By using live-imaging and computational modeling and tracking, they uncovered unique cellular behaviors that are associated with lineage specification during pre-implantation development, key to analyzing how various physical and chemical changes in the developing cell influence which genes are turned on.

Zheng was a Howard Hughes Medical Investigator from 2000 to 2012. She studied biology as an undergraduate in China before moving to Ohio State University where she received a PhD in 1992. She was a postdoctoral fellow at the University of California, San Francisco from 1992 to 1996, when she moved to Carnegie as a staff scientist and became Acting Director of the department in early 2016.  For more see the Zheng lab

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November 10, 2016

Baltimore, MD—A first-of-its-kind study on almost 20,000 K-12 underrepresented public school students shows that Project BioEYES, based at Carnegie’s Department of Embryology, is effective at increasing students’ science knowledge and positive attitudes about science. Younger students had the greatest attitude changes. The study covered five years and tested students before and after the one-week BioEYES program. The research is published in the November 10, 2016, issue of PLOS Biology.

BioEYES (www.bioeyes.org) uses live zebrafish to teach basic scientific principles, animal development, and genetics. The zebrafish embryo is clear, making it ideal for observations. Each BioEYES

Carnegie Science, Carnegie Institution, Carnegie Institution for Science
November 2, 2016

Baltimore, MD— New work led by Carnegie’s Steven Farber, with help from Yixian Zheng’s lab, sheds light on how form follows function for intestinal cells responding to high-fat foods that are rich in cholesterol and triglycerides. Their findings are published in the Journal of Biological Chemistry.

Enterocytes are specialized cells that line the insides of our intestines. The intestinal surface is like a toothbrush, with lots of grooves and protrusions that allow the cells there to grab and absorb nutrients from food as it is digested, including the lipid molecules from fatty foods. The cells absorb, process, and package these lipids for distribution throughout our bodies. Clearly

Carnegie Science, Carnegie Institution, Carnegie Institution for Science
October 5, 2016

Baltimore, MD---Athletes, the elderly and those with degenerative muscle disease would all benefit from accelerated muscle repair. When skeletal muscles, those connected to the bone, are injured, muscle stem cells wake up from a dormant state and repair the damage. When muscles age, however, stem cell number and function declines, as do both tissue function and regenerative ability.  Carnegie’s Christoph Lepper and team*, including researchers from the University of Missouri, investigated muscle stem cell pool size. In particular, they asked if stem cell number could be increased, and if there would be any associated functional benefits.

Using genetically modified mice, the

September 23, 2016

Washington, D.C.—  Zehra Nizami has been a graduate student and postdoc in Joe Gall’s lab at the Department of Embryology. She is the fourth recipient of the Postdoctoral Innovation and Excellence (PIE) Award, which are made through nominations from the department directors and chosen by the Office of the President. Her career at Embryology includes outstanding accomplishments in the three areas recognized by the PIE Award—science, education, and community service.

Nizami is co-discoverer of a new class of RNA molecules in amphibian egg cells called stable intronic sequence (sis) RNA. These sequences were not anticipated. It was believed for 35 years that introns—bits of DNA that

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The Zheng lab studies cell division including the study of stem cells, genome organization, and lineage specification. They study the mechanism of genome organization in development, homeostasis—metabolic balance-- and aging; and the influence of cell morphogenesis, or cell shape and steructure,  on cell fate decisions. They use a wide range of tools and systems, including genetics in model organisms, cell culture, biochemistry, proteomics, and genomics.

 

The Spradling laboratory studies the biology of reproduction. By unknown means eggs reset the normally irreversible processes of differentiation and aging. The fruit fly Drosophila provides a favorable multicellular system for molecular genetic studies. The lab focuses on several aspects of egg development, called oogenesis, which promises to provide insight into the rejuvenation of the nucleus and surrounding cytoplasm. By studying ovarian stem cells, they are learning how cells maintain an undifferentiated state and how cell production is regulated by microenvironments known as niches. They are  also re-investigating the role of steroid and prostaglandin hormones in controlling the

Stem cells make headline news as potential treatments for a variety of diseases. But undertstanding the nuts and bolts of how they develop from an undifferentiated cell  that gives rise to cells that are specialized such as organs, or bones, and the nervous system, is not well understood. 

The Lepper lab studies the mechanics of these processes. overturned previous research that identified critical genes for making muscle stem cells. It turns out that the genes that make muscle stem cells in the embryo are surprisingly not needed in adult muscle stem cells to regenerate muscles after injury. The finding challenges the current course of research into muscular dystrophy, muscle

The Marnie Halpern laboratory studies how left-right differences arise in the developing brain and discovers the genes that control this asymmetry. Using the tiny zebrafish, Danio rerio, they explores how regional specializations occur within the neural tube, the embryonic tissue that develops into the brain and spinal cord.

The zebrafish is ideal for these studies because its basic body plan is set within 24 hours of fertilization. By day five, young larvae are able to feed and swim, and within three months they are ready to reproduce. They are also prolific breeders. Most importantly the embryos are transparent, allowing scientists to watch the nervous system develop and to

Peter van Keken studies the thermal and chemical evolution of the Earth. In particularly he looks at the causes and consequences of plate tectonics; element modeling of mantle convection,  and the dynamics of subduction zones--locations where one tectonic plate slides under another. He also studies mantle plumes; the integration of geodynamics with seismology; geochemistry and mineral physics. He uses parallel computing and scientific visualization in this work.

He received his BS and Ph D from the University of Utrecht in The Netherlands. Prior to joining Carnegie he was on the faculty of the University of Michigan.

Peter Driscoll studies the evolution of Earth’s core and magnetic field including magnetic pole reversal. Over the last 20 million or so years, the north and south magnetic poles on Earth have reversed about every 200,000, to 300,000 years and is now long overdue. He also investigates the Earth’s inner core structure; core-mantle coupling; tectonic-volatile cycling; orbital migration—how Earth’s orbit moves—and tidal dissipation—the dissipation of tidal forces between two closely orbiting bodies. He is also interested in planetary interiors, dynamos, upper planetary atmospheres and exoplanets—planets orbiting other stars. He uses large-scale numerical simulations in much of his research

Andrew Newman works in several areas in extragalactic astronomy, including the distribution of dark matter--the mysterious, invisible  matter that makes up most of the universe--on galaxies, the evolution of the structure and dynamics of massive early galaxies including dwarf galaxies, ellipticals and cluster. He uses tools such as gravitational lensing, stellar dynamics, and stellar population synthesis from data gathered from the Magellan, Keck, Palomar, and Hubble telescopes.

Newman received his AB in physics and mathematics from the Washington University in St. Louis, and his MS and Ph D in astrophysics from Caltech. Before becomming a staff astronomer in 2015, he was a

Gwen Rudie studies the chemical and physical properties of very distant, so-called  high-redshift galaxies and their surrounding circumgalactic medium. She is primarily an observational astronomer working on the analysis and interpretation of high-resolution spectroscopy of high-redshift Quasi Stellar Objects and low to medium-resolution near-infrared and optical spectroscopy of high-redshift galaxies. She is interested in understanding the intergalactic medium as a tool for understanding galaxy evolution and the physical properties of very distant galaxies such as the composition of stars and their star formation rates

Rudie received her AB from Dartmouth College and her Ph D