Examination of the genetic basis for sexual dimorphism in the Aedes aegypti (dengue vector mosquito) pupal brain.
BACKGROUND
Most animal species exhibit sexually dimorphic behaviors, many of which are linked to reproduction. A number of these behaviors, including blood feeding in female mosquitoes, contribute to the global spread of vector-borne illnesses. However, knowledge concerning the genetic basis of sexually dimorphic traits is limited in any organism, including mosquitoes, especially with respect to differences in the developing nervous system.


METHODS
Custom microarrays were used to examine global differences in female vs. male gene expression in the developing pupal head of the dengue vector mosquito, Aedes aegypti. The spatial expression patterns of a subset of differentially expressed transcripts were examined in the developing female vs. male pupal brain through in situ hybridization experiments. Small interfering RNA (siRNA)-mediated knockdown studies were used to assess the putative role of Doublesex, a terminal component of the sex determination pathway, in the regulation of sex-specific gene expression observed in the developing pupal brain.


RESULTS
Transcripts (2,527), many of which were linked to proteolysis, the proteasome, metabolism, catabolic, and biosynthetic processes, ion transport, cell growth, and proliferation, were found to be differentially expressed in A. aegypti female vs. male pupal heads. Analysis of the spatial expression patterns for a subset of dimorphically expressed genes in the pupal brain validated the data set and also facilitated the identification of brain regions with dimorphic gene expression. In many cases, dimorphic gene expression localized to the optic lobe. Sex-specific differences in gene expression were also detected in the antennal lobe and mushroom body. siRNA-mediated gene targeting experiments demonstrated that Doublesex, a transcription factor with consensus binding sites located adjacent to many dimorphically expressed transcripts that function in neural development, is required for regulation of sex-specific gene expression in the developing A. aegypti brain.


CONCLUSIONS
These studies revealed sex-specific gene expression profiles in the developing A. aegypti pupal head and identified Doublesex as a key regulator of sexually dimorphic gene expression during mosquito neural development.
Eck Institute for Global Health, Galvin Life Sciences, University of Notre Dame, Notre Dame 46556, IN, USA ; Department of Biological Sciences, Galvin Life Sciences, University of Notre Dame, Notre Dame 46556, IN, USA.
Michael
M
Tomchaney
Eck Institute for Global Health, Galvin Life Sciences, University of Notre Dame, Notre Dame 46556, IN, USA ; Department of Medical and Molecular Genetics, Indiana University School of Medicine, Raclin-Carmichael Hall, South Bend 46617, IN, USA.
Keshava
K
Mysore
Eck Institute for Global Health, Galvin Life Sciences, University of Notre Dame, Notre Dame 46556, IN, USA ; Department of Biological Sciences, Galvin Life Sciences, University of Notre Dame, Notre Dame 46556, IN, USA.
Longhua
L
Sun
Eck Institute for Global Health, Galvin Life Sciences, University of Notre Dame, Notre Dame 46556, IN, USA ; Department of Medical and Molecular Genetics, Indiana University School of Medicine, Raclin-Carmichael Hall, South Bend 46617, IN, USA.
Ping
P
Li
Eck Institute for Global Health, Galvin Life Sciences, University of Notre Dame, Notre Dame 46556, IN, USA ; Department of Computer Science and Engineering, University of Notre Dame, Notre Dame 46556, IN, USA.
Scott J
SJ
Emrich
Eck Institute for Global Health, Galvin Life Sciences, University of Notre Dame, Notre Dame 46556, IN, USA ; Department of Biological Sciences, Galvin Life Sciences, University of Notre Dame, Notre Dame 46556, IN, USA ; Department of Medical and Molecular Genetics, Indiana University School of Medicine, Raclin-Carmichael Hall, South Bend 46617, IN, USA.
David W
DW
Severson
Eck Institute for Global Health, Galvin Life Sciences, University of Notre Dame, Notre Dame 46556, IN, USA ; Department of Biological Sciences, Galvin Life Sciences, University of Notre Dame, Notre Dame 46556, IN, USA ; Department of Medical and Molecular Genetics, Indiana University School of Medicine, Raclin-Carmichael Hall, South Bend 46617, IN, USA.
Molly
M
Duman-Scheel
Aedes aegypti; Brain; Development; Dimorphism; Doublesex; Mosquito; Nervous system; Optic lobe; Pupae; Vector