Mailing Address:
University of California, Berkeley
Dept. of Integrative Biology
3060 VLSB #3140
Berkeley, CA 94720-3140
Lab phone: 510/643-4201
Fax: 510/643-5022
Email: mikeperry@uclink.berkeley.edu
University of California, Berkeley
Dept. of Integrative Biology
3060 VLSB #3140
Berkeley, CA 94720-3140
Lab phone: 510/643-4201
Fax: 510/643-5022
Email: mikeperry@uclink.berkeley.edu
Research Interests
Segmentation in Parhyale hawaiiensis
Mechanisms of asymmetric cell division and planar cell polarity
There are two categories of mechanisms that might be used to pattern ectodermal segments derived from the regular division of cell rows in Parhyale. The first involves cell-extrinsic mechanisms of cell to cell signaling to determine row identity. The second involves cell-intrinsic mechanisms that would differentially partition determinants during mitotic divisions, and these determinants would then subsequently regulate genes that are expressed differentially between the two daughters. There is now some evidence from another project in our lab that patterning in the Parhyale ectoderm might involve cell intrinsic mechanisms.
I am beginning to further investigate this possibility by focusing on widely conserved mechanisms of asymmetric cell division, and attempting to determine if they might play a role in patterning Parhyale ectoderm. Some of these conserved mechanisms, such as those involved in sensory organ precursor divisions, might involve a combination of Notch signaling and asymmetric determinants. For example, in sensory organ precursor divisions, opposing protein complexes segregate at each cell division; proteins in these complexes are phylogenetically well conserved. Notch signaling has also been shown to play an important role in these same sensory organ precursor divisions. Another potential pathway that I am investigating involves differential beta-catenin nuclear localization that results from asymmetric anterior/posterior cell divisions. This work involves a combination of drug inhibitors and agonists of portions of the pathway, as well as possible over-expression experiments.
Planar cell polarity plays a role in providing directional information during asymmetric cell division events, and I am also beginning to characterize the localization of proteins such as Disheveled and Par6 in the Parhyale ectoderm. Cells in the most posterior region of the ectoderm do not exhibit any obvious polarity during division. The cells then line up into very regular rows (Parasegment Precursor Rows or PSPRs) and columns, but do not divide for several hours. Once division begins, however, the cells display a strict polarity to the orientation of mitosis. Each of the first two rounds of division occurs in a highly stereotyped way, with an anterior-posterior orientation, and with each daughter cell differentially expressing genes potentially involved in segmentation. Potential asymmetric determinants could rely on these planar cell polarity cues to segregate properly.
Notch signaling
I am continuing a project investigating the role of Notch signaling during segmentation in Parhyale hawaiiensis. Using the gamma-secretase inhibitor DAPT, we have found evidence that Notch plays a dynamic role in patterning events leading up to the first parasegmental precursor row (PSPR) division in the ectoderm. Continued work is aimed at determining if Notch signaling also plays a role in patterning events following the first wave of PSPR divisions by examining the expression of genes that mark specific rows formed by PSPR divisions in DAPT-treated embryos.
Butterfly wing pattern
Notch signaling in wing patterning
I am working with Berkeley undergraduate Amar Gupta on a project involving Notch signaling in developing butterfly wings. Previous work in another lab has discussed a possible role for Notch-mediated lateral inhibition (Reed 2003) in determining which cells become sensory organ precursors. We are using the gamma-secretase inhibitor DAPT in this context to examine the effect of interrupting Notch signaling on fate determination at each round of cell division leading from epidermal differentiation to socket/scale determination. At earlier time points, during larval disc development, we hope to knock down Notch signaling in order to begin to functionally test the hypothesized role of Notch expression on the inter-vein line in localizing the eyespot organizer. Figure 2 shows alternating ground and cover scales beginning to be produced in a 72-hour-after-pupation imaginal wing disc. Figure 3 shows overlapping ground and cover scales as the butterfly nears emergence.
Origins of the wing imaginal discs relative to compartment boundaries
Another project involves determining where the earliest imaginal precursors form during embryonic development, and where these groups of cells sit in relation to putative compartment boundaries. Here I am using expression of compartment-specific genes, and markers for the imaginal disc primordium to determine where boundaries fall. Figure 4 is of a butterfly embryo double labeled for wingless and hedgehog mRNA.
PhD candidate, University of California, Berkeley
Department of Integrative Biology
Dr. Nipam H. Patel, advisor
August 2006– present
M.S., Department of Zoology
University of Florida
2004-2006
B.S. in Zoology, and Microbiology and Cell Science
University of Florida
2000-2004
Fellowships and Grants
NSF Graduate Research Fellowship, 2006
Sigma Xi Grant in Aid of Research, 2004
University Scholars Program Grant (UF), 2003
Teaching Experience
Spring 2005
Teaching Assistant – General Biology Laboratory, University of Florida.
Segmentation in Parhyale hawaiiensis
Mechanisms of asymmetric cell division and planar cell polarity
There are two categories of mechanisms that might be used to pattern ectodermal segments derived from the regular division of cell rows in Parhyale. The first involves cell-extrinsic mechanisms of cell to cell signaling to determine row identity. The second involves cell-intrinsic mechanisms that would differentially partition determinants during mitotic divisions, and these determinants would then subsequently regulate genes that are expressed differentially between the two daughters. There is now some evidence from another project in our lab that patterning in the Parhyale ectoderm might involve cell intrinsic mechanisms.
I am beginning to further investigate this possibility by focusing on widely conserved mechanisms of asymmetric cell division, and attempting to determine if they might play a role in patterning Parhyale ectoderm. Some of these conserved mechanisms, such as those involved in sensory organ precursor divisions, might involve a combination of Notch signaling and asymmetric determinants. For example, in sensory organ precursor divisions, opposing protein complexes segregate at each cell division; proteins in these complexes are phylogenetically well conserved. Notch signaling has also been shown to play an important role in these same sensory organ precursor divisions. Another potential pathway that I am investigating involves differential beta-catenin nuclear localization that results from asymmetric anterior/posterior cell divisions. This work involves a combination of drug inhibitors and agonists of portions of the pathway, as well as possible over-expression experiments.
Planar cell polarity plays a role in providing directional information during asymmetric cell division events, and I am also beginning to characterize the localization of proteins such as Disheveled and Par6 in the Parhyale ectoderm. Cells in the most posterior region of the ectoderm do not exhibit any obvious polarity during division. The cells then line up into very regular rows (Parasegment Precursor Rows or PSPRs) and columns, but do not divide for several hours. Once division begins, however, the cells display a strict polarity to the orientation of mitosis. Each of the first two rounds of division occurs in a highly stereotyped way, with an anterior-posterior orientation, and with each daughter cell differentially expressing genes potentially involved in segmentation. Potential asymmetric determinants could rely on these planar cell polarity cues to segregate properly.
Notch signaling
I am continuing a project investigating the role of Notch signaling during segmentation in Parhyale hawaiiensis. Using the gamma-secretase inhibitor DAPT, we have found evidence that Notch plays a dynamic role in patterning events leading up to the first parasegmental precursor row (PSPR) division in the ectoderm. Continued work is aimed at determining if Notch signaling also plays a role in patterning events following the first wave of PSPR divisions by examining the expression of genes that mark specific rows formed by PSPR divisions in DAPT-treated embryos.
Butterfly wing pattern
Notch signaling in wing patterning
I am working with Berkeley undergraduate Amar Gupta on a project involving Notch signaling in developing butterfly wings. Previous work in another lab has discussed a possible role for Notch-mediated lateral inhibition (Reed 2003) in determining which cells become sensory organ precursors. We are using the gamma-secretase inhibitor DAPT in this context to examine the effect of interrupting Notch signaling on fate determination at each round of cell division leading from epidermal differentiation to socket/scale determination. At earlier time points, during larval disc development, we hope to knock down Notch signaling in order to begin to functionally test the hypothesized role of Notch expression on the inter-vein line in localizing the eyespot organizer. Figure 2 shows alternating ground and cover scales beginning to be produced in a 72-hour-after-pupation imaginal wing disc. Figure 3 shows overlapping ground and cover scales as the butterfly nears emergence.
Origins of the wing imaginal discs relative to compartment boundaries
Another project involves determining where the earliest imaginal precursors form during embryonic development, and where these groups of cells sit in relation to putative compartment boundaries. Here I am using expression of compartment-specific genes, and markers for the imaginal disc primordium to determine where boundaries fall. Figure 4 is of a butterfly embryo double labeled for wingless and hedgehog mRNA.
Education
PhD candidate, University of California, Berkeley
Department of Integrative Biology
Dr. Nipam H. Patel, advisor
August 2006– present
M.S., Department of Zoology
University of Florida
2004-2006
B.S. in Zoology, and Microbiology and Cell Science
University of Florida
2000-2004
Fellowships and Grants
NSF Graduate Research Fellowship, 2006
Sigma Xi Grant in Aid of Research, 2004
University Scholars Program Grant (UF), 2003
Teaching Experience
Spring 2005
Teaching Assistant – General Biology Laboratory, University of Florida.
NIPAM H. PATEL
TO LEFT:
Expression of Phhes-1, an ortholog of the Drosophila hairy/enhancer of split, in Parhyale hawaiiensis. This is one of a set of genes that are expressed in a row-specific manner after each wave of mitotic division in the Parhyale ectoderm, and can serve as a marker of cell fate in experiments such as those using the Notch pathway inhibitor DAPT.
Expression of Phhes-1, an ortholog of the Drosophila hairy/enhancer of split, in Parhyale hawaiiensis. This is one of a set of genes that are expressed in a row-specific manner after each wave of mitotic division in the Parhyale ectoderm, and can serve as a marker of cell fate in experiments such as those using the Notch pathway inhibitor DAPT.
TO LEFT:
Alternating ground and cover scales are beginning to be produced (72 hours after pupation) on the pupal wing disc of the Buckeye butterfly, Precis coenia. Staining in red is phalloidin, which labels actin, and in blue is DRAQ5, which binds DNA.
Alternating ground and cover scales are beginning to be produced (72 hours after pupation) on the pupal wing disc of the Buckeye butterfly, Precis coenia. Staining in red is phalloidin, which labels actin, and in blue is DRAQ5, which binds DNA.
TO LEFT:
An approximately 12 hour old butterfly embryo, stained for wingless in red and hedgehog in purple. We have been examining the location of the earliest imaginal disc primordia in relation to compartment boundaries in the early embryo (see text).
An approximately 12 hour old butterfly embryo, stained for wingless in red and hedgehog in purple. We have been examining the location of the earliest imaginal disc primordia in relation to compartment boundaries in the early embryo (see text).
TO LEFT:
As the butterfly nears emergence, scale production is nearly complete. Individual ridges of each scale can be seen; ground and cover scales overlap one another. Staining in red is phalloidin, which labels actin, and in blue is DRAQ5, which binds DNA.
As the butterfly nears emergence, scale production is nearly complete. Individual ridges of each scale can be seen; ground and cover scales overlap one another. Staining in red is phalloidin, which labels actin, and in blue is DRAQ5, which binds DNA.