Basic HTML Version
Poster Full Abstracts - Cell Death
Poster board number is above title. The first author is the presenter
219
sites. Double mutant analysis shows that the two types of euchromatic SC initiation can occur independently, however both pathways are dependent on
cohesion proteins SMC1 and SMC3. In addition, we have genetic evidence that suggests synapsis initiates at many locations along the chromosomes, which
may correspond to crossover sites. This data represents a novel model for SC initiation, which we hope to expand upon in order to gain more insight into the
mechanism behind synapsis initiation. To do this, we investigated synapsis in additional cohesion defective backgrounds. When the cohesion proteins
Stromalin (SCC3) and Nipped-B (SCC2) are knocked-down by RNAi we observed incomplete SC formation, similar to
c(2)M
mutants. Surprisingly, they
were not needed for centromere synapsis as SMC1 and SMC3 are. We are working to determine how these two proteins and others including RAD21
(SCC1), WAPL, ECO, and PDS5 contribute to the synapsis initiation pathway. This analysis of synapsis initiation begins to unweave the intricate details and
relationships that occur during meiotic prophase and gives insight into how proper chromosome segregation is accomplished.
323B
Heterologous segregation during
Drosophila
female meiosis I is preceded by heterologous coorientation at metaphase arrest.
Ashley Snouffer,
Wonbeom Paik, William Gilliland. Biological Science Department, DePaul University, Chicago, IL.
Heterologous Segregation is observed in flies with certain rearranged chromosomes, where non-homologous chromosomes are able to segregate away
from each other at high frequency, even though they do not pair. While the first observation of Heterologous Segregation was made over 70 years ago, it has
never been clear how chromosomes are able to segregate from each other without pairing. The recent discovery that female meiosis undergoes chromosome
congression prior to metaphase arrest provides a new step in meiosis where the coorientation of heterologous chromosomes could take place. If heterologous
segregation is a consequence of congression, then the coorientation of heterologous chromosomes at metaphase arrest should predict their eventual pattern of
segregation. We have examined metaphase-arrested oocytes in flies carrying multiple compound chromosomes that undergo heterologous segregation, using
chromosome-specific FISH. This demonstrated that heterologs are cooriented at the same high rates that they segregate. This demonstrates that congression
provides a mechanism for establishing heterologous segregation patterns.
324C
Genome-wide functional analysis of cyclic transcription in the developing
Drosophila
wing.
Liang Liang
1,2
, Matthew Gibson
1
. 1) Stowers Institute for
Medical Research, Kansas City, MO, USA; 2) OU program, UK.
The development of multicellular organisms relies on the coordinated control of cell division, growth and morphogenesis. Although previous studies have
analyzed global cell cycle-dependent transcription using single celled systems, precisely how cell cycle-dependent processes are integrated in the more
complex context of multicellular development remains unclear. Here, we report the global cell cycle-associated transcriptional profiles of
Drosophila
wing
disc epithelial cells (multicellular system) and cultured S2 cells (unicellular system). With an integrative FACS-microarray technique, we identified over 600
genes with cyclic expression profiles in each context. Intriguingly, despite the common cyclic genes identified, we identified 200 genes cyclically expressed
only in wing disc cells, including many core cell cycle components. Next, we explored the function of these wing disc cyclic genes by tissue-specific RNAi
knockdown. Combining flow cytometry and confocal imaging, we defined 95 cyclic genes that control wing growth, wherein 16 novel cyclic genes
controlled cell cycle progression in the developing wing but not in S2 cells (compared with results from S2 RNAi screens). In addition to several novel
regulators of mitotic cell size and chromosome segregation, we also identified two novel cyclic genes that control Interkinetic Nuclear Migration (IKNM), a
conserved process by which mitotic nuclei translocate to the apical epithelial surface during mitosis. Taken together, our studies reveal a surprising degree of
plasticity of cell cycle regulation at the level of cyclic transcription, and identify several novel genes that control growth and cell proliferation in tissue
development.
325A
Cytokinesis-deficient binucleation in
Drosophila
accessory gland for providing plasticity of organ size.
Kiichiro Taniguchi
1
, Akihiko Kokyuryo
1,2
,
Takao Imano
1,2
, Rumi Sakata
1
, Ryunosuke Minami
3
, Hideki Nakagoshi
3
, Takashi Adachi-Yamada
1,2
. 1) Dept. of Life Sci., Gakushuin Univ., Japan; 2) Dept.
of Biol., Grad. Sch. of Sci., Kobe Univ., Japan; 3) Dept. of Biol., Grad. Sch. of Nat. Sci./Tech., Okayama Univ., Japan.
As cytokinesis theoretically follows karyokinesis during the M phase in a cell cycle, most eukaryotic cells contain only a single nucleus. Nonetheless,
cytokinesis does not occur in particular kinds of cells, such as myocyte, which results in cells containing two nuclei. However, mechanisms to skip
cytokinesis and the significance of binucleation are largely unknown. Here, we examined the binucleation by using the
Drosophila
adult male accessory
gland, a reproductive organ producing seminal fluid proteins. All of the accessory gland epithelial cells are binucleated by cytokinesis-skipping at the final
mitosis.
First, we examined the mechanisms to skip cytokinesis in binucleation. As a result, both the central spindle and contractile ring did not form during
binucleation. Thereby, the activity of Rho GTPase was insufficient to drive cytokinesis completion. Moreover, we found out that Mud, a
Drosophila
NuMA,
was a key regulator of binucleation, which impaired the central spindle formation and following cytokinesis. These results suggest that impairment of central
spindle formation by NuMA leads to a restriction of Rho activity to skip cytokinesis in binucleation. Second, we elucidated the significance of binucleated
state of cells. We compared the apical area in adult accessory gland cells between binucleated, endoreplicated and divided cells. The apical area of
binucleated cells became more enlarged than that in endoreplicated mononucleate cells. On the other hand, the apical area of binucleated cells became more
shrunken after mating than that of divided mononucleate cells. These results suggest binucleation is an effective strategy to provide a higher plasticity in the
apical area size, which turns out that in the organ volume.
326B
Identifying mutations in the chromosomal passenger complex and associated regulators of spindle assembly.
Arunika Das
1
, Shital Shah
2
, Kim
McKim
1
. 1) Waksman Institute, Rutgers University, Piscataway, NJ; 2) University of Medicine and Dentistry, New Jersey.
Accurate segregation of chromosomes during cell division is facilitated by the formation of a bipolar array of microtubules known as the spindle. Kinesin
motor proteins are known to regulate microtubule dynamics of spindle formation. Kinesin 6 family member Subito regulates bipolar spindle assembly and
interacts with the components of the chromosomal passenger complex (CPC), like
Incenp
or
ial
, which encodes for Aurora B. A homozygous mutation in
subito
is synthetic lethal with a heterozygous mutation in a component of the CPC like
Incenp
or
ial
, which led us to hypothesize that
subito
may also