922 research outputs found
Crossroads, Milestones, amd Landmarks in Insect Development and Evolution: Implications for Systematics
Our understanding of insect development and evolution has increased greatly due to recent advances in the comparative developmental approach. Modem developmental biology techniques such as in situ hybridization and molecular analysis of developmentally important genes and gene families have greatly facilitated these advances. The role of the comparative developmental approach in insect systematics is explored in this paper and we suggest two important applications of the approach to insect systematics--character dissection and morphologicallandmarking. Exi~ng morphological characters can be dissected into their genetic and molecular components in some cases and this will lead to more and richer character information in systematic studies. Character landmarking will be essential - to systematic studies for clarifying structures such as shapes or convergences, which are previously hard to analyze anatomical regions. Both approaches will aid greatly in expanding our understanding of homology in particular, and insect development in general
Evolution of Sex-Specific Traits through Changes in HOX-Dependent doublesex Expression
Analysis in Drosophila suggests that evolutionary changes in the spatial regulation of the transcription factor doublesex play a key role in the origin, diversification, and loss of sex-specific structures
Genome-Wide Tissue-Specific Occupancy of the Hox Protein Ultrabithorax and Hox Cofactor Homothorax in Drosophila
The Hox genes are responsible for generating morphological diversity along the
anterior-posterior axis during animal development. The
Drosophila Hox gene Ultrabithorax
(Ubx), for example, is required for specifying the identity
of the third thoracic (T3) segment of the adult, which includes the dorsal
haltere, an appendage required for flight, and the ventral T3 leg.
Ubx mutants show homeotic transformations of the T3 leg
towards the identity of the T2 leg and the haltere towards the wing. All Hox
genes, including Ubx, encode homeodomain containing
transcription factors, raising the question of what target genes
Ubx regulates to generate these adult structures. To
address this question, we carried out whole genome ChIP-chip studies to identify
all of the Ubx bound regions in the haltere and T3 leg imaginal discs, which are
the precursors to these adult structures. In addition, we used ChIP-chip to
identify the sites bound by the Hox cofactor, Homothorax (Hth). In contrast to
previous ChIP-chip studies carried out in Drosophila embryos,
these binding studies reveal that there is a remarkable amount of tissue- and
transcription factor-specific binding. Analyses of the putative target genes
bound and regulated by these factors suggest that Ubx regulates many downstream
transcription factors and developmental pathways in the haltere and T3 leg.
Finally, we discovered additional DNA sequence motifs that in some cases are
specific for individual data sets, arguing that Ubx and/or Hth work together
with many regionally expressed transcription factors to execute their functions.
Together, these data provide the first whole-genome analysis of the binding
sites and target genes regulated by Ubx to specify the morphologies of the adult
T3 segment of the fly
Robust Target Gene Discovery through Transcriptome Perturbations and Genome-Wide Enhancer Predictions in Drosophila Uncovers a Regulatory Basis for Sensory Specification
CisTarget X is a novel computational method that accurately predicts Atonal governed regulatory networks in the retina of the fruit fly
- β¦