Imaging of baculovirus actin comet tails. Mueller J, Planzehter J, Winkler C, Nanta A et al. (2014) Fifi PLS novocr Above are several images from a recent paper "Electron Tomography and Simulation of Baculovirus Actin Comet Tails Support a Tethered Filament Model of Pathogen Propulsion". Although Baculovirus is a virus, it hijacks actin and its regulatory proteins in host cells to move within the cytoplasm and out of the cell, like Listeria does. Because the virus is small, it is easier to image in very high resolution. In panel A, localization of the viral particle, actin, and associated proteins along the actin comet tail are quantified. (If it is hard to see the colors, the curves of the graphs from left to right correspond to top to bottom descriptions in the key). Panel B shows a negatively stained image of the actin comet tail viewed by electron microscopy in 3D. The virus particle is on the right (BV). Panel C depicts actin filaments from Panel B, with large black circles indicating the plus ends (small circles indicate branch points). Scale bar is 100nm. Use this information and what you learned in class to answer the following 4 questions. 6. Panel A shows that nucleating proteins (Arp), branching (VASP), capping (CPb) and filament severing (cofilin) proteins are present along the comet tail. Given this initial finding, which hypothesis do you think the authors intended to test? a. Comet tail dynamics depend on multiple host proteins, not just nucleation, and tails may have more complicated structures than that of a single filament. b. Comet tail dynamics depend on multiple host proteins, including those needed to regulate microtubule dynamics. c. Comet tail dynamics depend on multiple host proteins, not just nucleation, which all function to promote rapid extension of a single filament. d. Comet tails are made up of many proteins (Arp, WASP, BP) that all polymerize together to create a larger structure than just a thin actin filament. 7. Actin polymerizing proteins are recruited to the surface of the pathogens to create comet tails. Considering the data shown in the figures, and the authors' additional report that baculoviral comet tails average 3.8+/1m in length, approximately how far from the virus is the highest level of cofilin?a. 100nm d. 3.8m b. 1.9m e. 7.6m c. 0.95m.

1. Imaging of baculovirus actin comet tails. Mueller J, Planzehter J, Winkler C, Nanta A et al. (2014)
Fifi PLS novocr Above are several images from a recent paper "Electron Tomography and
Simulation of Baculovirus Actin Comet Tails Support a Tethered Filament Model of Pathogen
Propulsion". Although Baculovirus is a virus, it hijacks actin and its regulatory proteins in host cells
to move within the cytoplasm and out of the cell, like Listeria does. Because the virus is small, it is
easier to image in very high resolution. In panel A, localization of the viral particle, actin, and
associated proteins along the actin comet tail are quantified. (If it is hard to see the colors, the
curves of the graphs from left to right correspond to top to bottom descriptions in the key). Panel B
shows a negatively stained image of the actin comet tail viewed by electron microscopy in 3D. The
virus particle is on the right (BV). Panel C depicts actin filaments from Panel B, with large black
circles indicating the plus ends (small circles indicate branch points). Scale bar is 100nm. Use this
information and what you learned in class to answer the following 4 questions. 6. Panel A shows
that nucleating proteins (Arp), branching (VASP), capping (CPb) and filament severing (cofilin)
proteins are present along the comet tail. Given this initial finding, which hypothesis do you think
the authors intended to test? a. Comet tail dynamics depend on multiple host proteins, not just
nucleation, and tails may have more complicated structures than that of a single filament. b.
Comet tail dynamics depend on multiple host proteins, including those needed to regulate
microtubule dynamics. c. Comet tail dynamics depend on multiple host proteins, not just
nucleation, which all function to promote rapid extension of a single filament. d. Comet tails are
made up of many proteins (Arp, WASP, BP) that all polymerize together to create a larger
structure than just a thin actin filament. 7. Actin polymerizing proteins are recruited to the surface
of the pathogens to create comet tails. Considering the data shown in the figures, and the authors'
additional report that baculoviral comet tails average 3.8+/1m in length, approximately how far
from the virus is the highest level of cofilin?a. 100nm d. 3.8m b. 1.9m e. 7.6m c. 0.95m