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Poster Full Abstracts - RNA Biology
Poster board number is above title. The first author is the presenter
349
Fredericton, New Brunswick, Canada.
Pseudogenes are generally considered to be non-functional due to mutations. However, some pseudogenes are transcribed and functional. For instance, in
flies and mice, some pseudogenes play a role in regulating the expression of closely related genes through the endogenous small interfering RNA (siRNA)
pathway. This work focuses on
CR14033
, a pseudogene copy of
CG9203
. Both genes are highly maternally expressed and
CG9203
has a domain associated
with DNA repair. Compared to
CG9203
, the
CR14033
coding region has nonsense and frameshift mutations yet it has retained 73% nucleotide sequence
identity with
CG9203
across 41% of its transcript length. High throughput sequencing of RNAs bound to AGO2 identified small RNAs with sequences
shared between
CR14033
and
CG9203
. Furthermore, the level of intact
CG9203
transcript is enhanced in the male germline of a
Dcr-2
mutant, supporting a
role for the siRNA pathway in its regulation (Czech
et al.
2008). We are examining the functions of
CG9203
and
CR14033
using P element excision to make
deletion mutations. Of the 19 independent excisions of
P{SUPor-P}CG9203
KG05829
, all but one are viable. Two P element insertions were used to generate
excisions from the
CR14033
region. For one P element insertion,
P{SUPor-P}tkv
KG01923
, 15 independent excisions were generated and 11 of these have a
similar large clear-body 3
rd
instar larval lethal phenotype.
CR14033
lies in an intron of thickveins, yet we found that the 11 lethal alleles complement a
tkv
allele. For the other P element insertion,
P{lacW}l(2)k01302
k01302
, 24 independent excisions are all viable when uncovered by a deficiency of the
tkv
region.
PCR amplification of genomic DNA from the 11 lethal mutant homozygotes using primers flanking the P element insertion site shows variations in product
size. Further mapping of these mutations, combined with sequencing and transcript analysis, is now being done to determine if they are indeed lethal alleles
of
CR14033
.
814A
The roles of
Drosophila RNase Z
L
in mitochondrial function and dysfunction.
Xie Xie, Veronica Dubrovskaya, Nancy Yacoub, Tara Gleason, Joanna
Walska, Edward Dubrovsky. Biological Sciences, Fordham University, Bronx, NY.
Drosophila RNase Z
L
(
dRNaseZ
) encodes a member of the ELAC1/ELAC2 protein family with homologs in every living organism. Previously, we showed
that dRNaseZ is involved in nuclear and mitochondrial tRNA 3’-end maturation and is essential for viability. Tissue-specific knockdown of dRNaseZ affects
cell proliferation in imaginal discs and cell growth in endoreplicating salivary glands. In this study, we analyzed the subcellular localization of dRNaseZ, and
identified the functional mitochondrial targeting signal (MTS) and nuclear localization signal (NLS). Using GAL4/UAS system, we ubiquitously expressed a
mutant construct lacking MTS (
RNZ
ΔMTS
) in
dRNaseZ
knockout animal.
RNZ
ΔMTS
larvae arrested their development at the third larval instar and survived for
at least 2 weeks with reduced body mass. As expected, these larvae display a strong reduction in mitochondrial activity; however, they have a 3-fold increase
in mitochondrial DNA level. Since the mitochondrial genome encodes 22 tRNAs that are transcribed within long polycistronic transcripts separating the
mRNA and rRNA genes, precise endonucleolytic cleavages before and after tRNA sequences are required to yield the mature mRNA/rRNA transcripts.
Northern blot analysis revealed that mitochondrial specific knockout of
dRNaseZ
affects not only the generation of mature tRNA, but also affects the
processing of mitochondrial mRNA and rRNA molecules. We therefore conclude that the mitochondrial dRNaseZ is responsible for the normal functionality
of this organelle.
815B
The role of piRNAs in genome stability and germline maintenance in
Drosophila virilis
.
Mauricio Galdos
2
, Chris Harrison
1
, Kim Box
1
, Michelle
Wickersheim
1
, Christine Yoder
1
, Jianwen Fang
3
, Justin Blumenstiel
1
. 1) Ecology and Evolutionary Biology, University of Kansas, Lawrence, KS; 2)
Molecular Biosciences, University of Kansas, Lawrence, KS; 3) Applied Bioinformatics Lab, University of Kansas, Lawrence, KS.
Transposition, natural selection and RNA silencing are three forces that jointly determine transposable element (TE) proliferation. piRNAs are a class of
small RNAs that are essential for epigenetic regulation of TEs in animals. They are primarily found in the germline, where they control TE mobilization
through a Dicer-independent pathway. In our current study, we investigate the role of piRNAs in protecting the germline using the hybrid dysgenesis system
in
Drosophila virilis
. In this system, when male flies with a higher TE copy number are mated with females that have a reduced copy number, progeny
become sterile. This is likely due to TE mobilization in the germline. In this particular system, we have found that protective mothers have much higher
levels of piRNA abundance corresponding to TEs that mobilize in the progeny, including the telomeric TART elements. We have also found that TEs appear
generally destabilized in the inducer strain. Furthermore, we have determined that the degree of hybrid sterility is highly dependent on the dose of inducer
chromosomes, either present in the mother, or inherited from the father. These results suggest that genome instability can be an inherent feature that can be
transmitted across generations in an epigenetic and dose dependent manner.
816C
U bodies respond to nutrient stress in
Drosophila
.
MICKEY BUCKINGHAM, JI-LONG LIU. MRC Functional Genomics Unit, Department of
Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom.
The neurodegenerative disease spinal muscular atrophy (SMA) is caused by mutation of the
survival motor neuron 1 (SMN1)
gene. Cytoplasmic SMN
protein-containing granules, known as U snRNP bodies (U bodies), are thought to be responsible for the assembly and storage of small nuclear
ribonucleoproteins (snRNPs) which are essential for pre-mRNA splicing. U bodies exhibit close association with cytoplasmic processing bodies (P bodies),
which are involved in mRNA decay and translational repression. The close association of the U body and P body in
Drosophila
resemble that of the stress
granule and P body in yeast and mammalian cells. However, it is unknown whether the U body is responsive to any stress. Using
Drosophila
oogenesis as a
model, this study compares the morphology of U bodies and the U body-P body interaction between well-fed and starved
Drosophila
. Here we show that U
bodies increase in size following nutritional deprivation. Despite nutritional stress, U bodies maintain their close association with P bodies. Our results show
that U bodies are responsive to nutrition changes, presumably through the U body-P body pathway.
817A
Characterization of in vivo targets of the nuclear RNA-binding protein Lark during oogenesis.
Christopher Ferrari
1
, Gerard McNeil
1,2
. 1) Doctoral
Program in Biology, The Graduate Center, The City University if New York, New York, NY; 2) Department of Biology, York College, The City University
if New York, Jamaica, NY.
Early Drosophila development is controlled by maternal gene expression. It is these maternally expressed gene products that are required for development