organisation - the Instituto Gulbenkian de Ciência

DEVELOPMENT,
EVOLUTION
AND THE ENVIRONMENT
Christen Mirth Principal Investigator
PhD in Zoology, University of Cambridge, UK, 2002
Post-doctoral associate, Department of Zoology, University of Wahsington, Seattle, USA
Research Specialist, Janelia Farm Research Campus, HHMI, Ashburn, USA
Principal Investigator at the IGC since 2010
link to external website
Our lab studies the regulation and evolution of environmentally-dependent
traits in species from the genus Drosophila. Recently, our efforts have focused
on two traits that depend on nutritional cues:
1. Body size;
2. Larval foraging behaviour.
We use the genetic tools available in Drosophila melanogaster to dissect how environmental
signals, like nutrition, regulate larval growth and foraging choices.
By analysing the changes in these mechanisms across species, we hope to identify
how these environmentally-dependent traits evolve to create species-specific
differences in foraging behaviour and adult body size.
GROUP MEMBERS
Takashi Koyama (Post-doc)
Marisa Oliveira (PhD Student)
Cláudia Mendes (PhD Student, started in April)
Sara Lennox (Technician)
Marisa Rodrigues (Trainee)
COLLABORATORS
Alexander Shingleton (Department of Zoology, Michigan State University, USA)
Élio Sucena (IGC, Portugal)
Marta Zlatic (Janelia Farm Research Campus, Howard Hughes Medical
Institute, USA)
FUNDING
Calouste Gulbenkian Foundation, Portugal
NUTRITION-DEPENDENT REGULATION OF BODY SIZE
IN Drosophila melanogaster
Organisms of all phyla regulate their body size in response to a number of environmental
factors, including nutrition. Both the rate of growth and the length of
the growth period determine final body size. Nutrition regulates growth rates
via the insulin and target of rapamycin (TOR) pathways. In insects, a size-dependent
checkpoint, known as critical weight, determines when growth ceases.
Insulin and TOR signaling in the prothoracic gland (PG) regulates critical weight
by controlling on the production of the steroid hormone ecdysone. Thus nutrition
directly affects both the rate and duration of the growth period. We aim to
understand how nutrition regulates final body size by:
1. Investigating how insulin/TOR controls the nutrition-dependent synthesis
of ecdysone;
2. Determine the role of ecdysone signalling on the growth and differentiation
of the developing adult tissues.
Two manuscripts are in preparations:
Oliveira, M.M., Shingleton, A.W. & Mirth, C.K. (in preparation). How old are you?
A new tool using gene patterning to characterise developmental time in Drosophila
larvae.
Mirth, C.K.,Tang,H.Y., Makhon-Moore, S., Salhadar, S., Riddiford, L.M. & Shingleton,
A.W. (in preparation). Juvenile Hormone controls body size by regulating
insulin signalling in Drosophila.
THE ENVIRONMENTAL REGULATION AND EVOLUTION OF FORAGING
STRATEGIES IN THE GENUS Drosophila
The environment and evolution act to generate a vast diversity of foraging strategies
in insects. We examine two aspects of foraging behaviour: how environmental
cues interact with development to regulate larval foraging behaviour in
D. melanogaster and how behavioural suites evolve to produce differences in
larval foraging strategies between species of the genus Drosophila.
Our most recent efforts investigate the evolution of larval foraging behaviour
using a collection of 47 species of Drosophila. To date, we have analysed all
species for burrowing behaviour. We are continuing our exploration by characterising
the array of behaviours observed when larvae come into contact on
the surface of the food. Exploring these behaviours allows us to generate a
behavioural profile for each species.
We use these profiles to identify closely related species exhibiting divergent
behaviours. Our ultimate goal is to identify genomic sites responsible for the
evolution of foraging strategies. A manuscript is in preparation:
Rivera Alba, M., Kelstrup, H.C.P., Riddiford, L.M. & Mirth, C.K. (in preparation).
The evolution of burrowing behaviour in fruit flies from the genus Drosophila.
Knocking down FoxO and Usp in the prothoracic gland (PG) causes premature
expression of Senseless (Sens) in wing discs of larvae starved of protein. A) A
wing disc from a control larva (PG>). B) A wing disc from a larva in which FoxO is
knocked down in the PG. C) A wing disc from a larva in which Usp is knocked down
in the PG. D) A wing disc from a larva in which both FoxO and Usp are knocked
down in the PG. Arrows point to Sens positive sensory organ precursors.
IGC ANNUAL REPORT ‘11
RESEARCH GROUPS
52