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Poster Full Abstracts - Evolution and Quantitative Genetics
Poster board number is above title. The first author is the presenter
255
compound eye. In
Tribolium
, by contrast, adult eye development is only mildy sensitive to RNAi mediated knockdown of
toy
and
ey
apparently due to
redundant regulation which involves the transcription factor
dachshund (dac)
. We employed next generation sequencing to further elucidate the architecture
of the
Tribolium
RDGN, comparing the pupal head transcriptomes of untreated,
dac
and
dac+ey+toy
knockdown animals. In addition, we investigated the
transcriptome of eye- depleted pupae from animals injected with dsRNA targeting the
eyes absent (eya)
transcription factor genes. These experiments
identified 2954 candidate eye developmental regulators, 557 of which appear to specifically depend on the synergistic input of
dac
,
ey
and
toy
. In addition,
we identified 362 genes whose expression is enriched in the developing head of eye-depleted animals. We hypothesize that the latter define gene regulatory
specification networks that are antagonistic to eye determination in the developing
Tribolium
head.
457A
New models to Diptera development: Clogmia albipunctata and Megaselia abdita.
Eva Jimenez, Karl R. Wotton, Yogi Jaeger. Systems Biology Unit,
Centre de Regulacio Genomica, PRBB, Barcelona, Spain.
We aim to study the evolution of gene networks by comparing the well characterised gene networks of the fruit fly Drosophila melanogaster with 2 further
fly species: Megaselia abdita and Clogmia albipunctata. Clogmia belongs to a lineage of flies believed to have diverged early in the evolution of the
dipterans, while the lineage leading to Megaselia branched intermediately; at the base of the cyclorraphans. To develop these species as models we are
documenting some classic biology concerning their life cycles and early development. This includes the description of cleavage cycles and other
morphological events using nuclear staining, fluorescence, confocal and time-lapse imaging. Furthermore, we are characterising the transcriptomes of pre-
gastrulating embryos of both species. This morphological and molecular information will be used to aid the investigation into evolving gene networks such
as those involved in segmentation, heart development and bristle patterning using traditional (in situ staining, RNAi) and computational approaches (reverse-
engeneering).
458B
Common and distinct roles of juvenile hormone signaling genes in metamorphosis of holometabolous and hemimetabolous insects.
Marek Jindra
1
,
Barbora Konopova
1
, Vlastimil Smykal
2
. 1) Biology Center ASCR, Ceske Budejovice, Czech Republic; 2) University of South Bohemia, Ceske Budejovice,
Czech Republic.
Insect larvae metamorphose to winged and reproductive adults either directly (hemimetaboly) or through an intermediary pupal stage (holometaboly). In
either case juvenile hormone (JH) prevents metamorphosis until a larva has attained an appropriate phase of development. In holometabolous insects, JH acts
through its putative receptor Methoprene-tolerant (Met) to regulate
Krüppel-homolog 1
(
Kr-h1
) and
Broad-Complex
(
BR-C
) genes. While Met and Kr-h1
prevent precocious metamorphosis in pre-final larval instars, BR-C specifies the pupal stage. How JH signaling operates in hemimetabolous insects is poorly
understood. Here, we compare the function of
Met
,
Kr-h1
and
BR-C
genes in the two types of insects. Using systemic RNAi in the hemimetabolous true bug,
Pyrrhocoris apterus
, we show that Met conveys the JH signal to prevent premature metamorphosis by maintaining high expression of
Kr-h1
. Knockdown of
either
Met
or
Kr-h1
(but not of
BR-C
) in penultimate-instar
Pyrrhocoris
larvae causes precocious development of adult color pattern, wings and genitalia. A
natural fall of
Kr-h1
expression in the last larval instar normally permits adult development, and treatment with an exogenous JH mimic methoprene at this
time requires both
Met
and
Kr-h1
to block the adult program and induce an extra larval instar. Met and Kr-h1 therefore serve as JH-dependent repressors of
deleterious precocious metamorphic changes in both hemimetabolous and holometabolous juveniles, whereas BR-C has been recruited for a new role in
specifying the holometabolous pupa. These results show that despite considerable evolutionary distance, insects with diverse developmental strategies
employ a common-core JH signaling pathway to commit to adult morphogenesis.
459C
High Hemocyte Load Is Associated With Increased Resistance Against Parasitoids in Drosophila suzukii, A Relative of D. melanogaster.
Balint Z.
Kacsoh, Todd A. Schlenke. Department of Biology, Emory University, Atlanta, GA.
Among the most common parasites of Drosophila in nature are parasitoid wasps, which lay their eggs in fly larvae and pupae. D. melanogaster larvae can
mount a cellular immune response against wasp eggs, but female wasps inject venom along with their eggs to block this immune response. Genetic variation
in flies for immune resistance against wasps and genetic variation in wasps for virulence against flies largely determines the outcome of any fly-wasp
interaction. Interestingly, up to 90% of the variation in fly resistance against wasp parasitism has been linked to a very simple mechanism: flies with
increased constitutive blood cell (hemocyte) production are more resistant. However, this relationship has not been tested for Drosophila hosts outside of the
melanogaster subgroup, nor has it been tested across a diversity of parasitoid wasp species and strains. We compared hemocyte levels in two fly species from
different subgroups, D. melanogaster and D. suzukii, and found that D. suzukii constitutively produces up to five times more hemocytes than D.
melanogaster. Using a panel of 24 parasitoid wasp strains representing fifteen species, four families, and multiple virulence strategies, we found that D.
suzukii was significantly more resistant to wasp parasitism than D. melanogaster. Thus, our data suggest that the relationship between hemocyte production
and wasp resistance is general. However, at least one sympatric wasp species was a highly successful infector of D. suzukii, suggesting specialists can
overcome the general resistance afforded to hosts by excessive hemocyte production. Given that D. suzukii is an emerging agricultural pest, identification of
the few parasitoid wasps that successfully infect D. suzukii may have value for biocontrol.
460A
The effects of temperature on developmental timing in species with different optimal growth temperatures.
Steven G. Kuntz
1
, Michael B. Eisen
1,2
. 1)
Department of Molecular and Cell Biology, University of California, Berkeley, CA; 2) Howard Hughes Medical Institute, University of California,
Berkeley, CA.
Drosophila
species live in a variety of different climates and must adapt to their local environments. The genus includes tropical species that prefer
relatively warm climates and temperate species that prefer relatively low temperatures. Species such as
Drosophila melanogaster
and
D. simulans
are able to
adapt to a broad range of temperatures and have become cosmopolitan. Others, such as
D. sechellia
and
D. mojavensis
(subspecies
wrigleyi
), are restricted to
small islands with a stable, uniform climate and may have lost the ability to radiate in the same way. The impact of temperature, which is known to affect the
rate of development, on the embryonic development of species adapted to a single climate versus species adaptable to multiple climates is not known,