Basic HTML Version
Poster Full Abstracts - Immunity and Pathogenesis
Poster board number is above title. The first author is the presenter
293
steroid input, we observe a severe phenotype (melanotic nodule formation and reduced survival to adulthood) which may be related to defective immune
function.
604A
Wolbachia show asymmetric localization to embryonic and larval neuroblasts and target specific neuronal cell bodies in the D. melanogaster adult
brain.
Roger Albertson
1
, Rachel Leads
1
, William Sullivan
2
. 1) Albion College, Albion, MI; 2) University of California at Santa Cruz, Santa Cruz, CA.
Wolbachia is a maternally transmitted bacterial endosymbiont that infects germline and somatic tissues of arthropods. We show that in both D.
melanogaster and D. simulans, various strains of Wolbachia including wRiv, wMel, and wPop, asymmetrically localize to neuroblast stem cells during
embryonic and larval development. Later in development, Wolbachia localize to specific areas of the adult brain, causing a high titer in those areas. Through
confocal microscopy and fluorescent imaging of D. melanogaster adult brains, we show that wMel and wPop localize to neuronal cell bodies but not to
axons, such as mushroom body axons. Elav and phalloidin staining suggests that wMel and wPop hyperproliferation within host cells leads to cell lysis. This
is most striking in hosts infected with wPop. Relative to embryos and newly eclosed adult flies, hyperproliferation of wPop in the D. melanogaster CNS is
most prominent after seven days of adult development.
605B
Evolutionary analysis of the
bag of marbles
gene reveals an interaction with
Wolbachia
.
Heather A. Flores, Daniel A. Barbash, Charles F. Aquadro.
Dept Molec Biol & Gen, Cornell Univ, Ithaca, NY.
Drosophila germline stem cells (GSCs) can both self-renew and differentiate to give rise to oocytes or sperm thus making them the evolutionary target of
mutations and pathogens trying to ensure their transmission. We have shown that multiple genes involved in GSC regulation are experiencing rapid, adaptive
protein evolution in
Drosophila melanogaster
and the closely related species,
D. simulans
, suggesting that it is beneficial for these proteins to accumulate
amino acid changes. We have focused on one of these adaptively evolving genes,
bag of marbles
(
bam
), to understand the functional consequences of this
adaptive evolution. The best characterized function of
bam
is initiating GSC differentiation in ovaries. We are using interspecies complementation to test
whether adaptive evolution of
bam
has caused detectable functional differences. We have assayed the ability of a
bam
ortholog from
D. simulans
to
complement the male and female sterility associated with a
bam
mutation in
D. melanogaster
. We have found that the
D. simulans bam
ortholog can
complement male sterility but fails to fully complement the female sterility in
D. melanogaster
. These data suggest that the evolutionary force driving the
diversification of
bam
may be focused on the female germline, and we hypothesize this force may be conflict with bacterial endosymbionts due to their
maternal inheritance and reproductive manipulation. The endosymbiont
Wolbachia pipientis
is an obligate, intracellular bacterium that has been shown to
manipulate the germline in a variety of insects. To determine if any interaction existed between
bam
and
Wolbachia
, we tested the ability of
Wolbachia
to
suppress
D. melanogaster bam
hypomorphic mutants and found that the presence of
Wolbachia
can suppress
bam
female sterility. We also found that
Wolbachia
can enhance the female fertility in flies with
D. simulans
transgenic
bam
in our complementation assay. We are currently examining the nature of
the interaction between
bam
and
Wolbachia
to try and understand the mechanism of suppression.
606C
Density of
Wolbachia
in the host insect impacts antiviral protection.
Karyn N Johnson
1
, Sheree E Osborne
1
, Jeremy C Brownlie
2
. 1) School of Biological
Sciences, The University of Queensland, Brisbane, Queensland, Australia; 2) School of Biomolecular and Physical Sciences, Griffith University, Brisbane,
Australia.
Recently the maternally inherited endosymbiotic bacteria
Wolbachia
has been shown to protect insects from a range of microbial and eukaryotic
pathogens.
Wolbachia
-mediated antiviral protection has been demonstrated in
Drosophila
and mosquitoes against RNA viruses, including
Drosophila C
virus
and
Dengue virus
. To explore the mechanism of antiviral protection, we screened five diverse strains of
Wolbachia
within their naturally associated
Drosophila simulans
hosts, to determine if antiviral protection occurred across all
Wolbachia
strains. Although three of the
Wolbachia
strains delayed viral
induced mortality, the other two strains did not. The three strains that mediated antiviral protection were more closely related and more abundant in the host
than the two non-protective strains. We investigated the importance of
Wolbachia
density within the insect host on antiviral protection. To do this, we used
low doses of antibiotic to decrease the density of a protective
Wolbachia
strain in its natural host, to levels that were similar to those observed in the two
non-protective
Wolbachia
strains. Flies were then challenged with the pathogenic
Drosophila C virus
. It was found that when the density of the previously
protective
Wolbachia
strain
w
Au was decreased,
Wolbachia
-mediated antiviral protection was substantially decreased or lost completely. This data suggests
that the density of
Wolbachia
in the insect host is important for the mechanism of antiviral mediated protection and suggests that insects carrying low load of
Wolbachia
will likely not be protected. These findings may facilitate prediction of
Wolbachia
-mediated protection in host-
Wolbachia
associations relevant
for the biocontrol of insect-borne viruses.