Project description:Venoms have convergently evolved in all major animal lineages and are ideal candidates to unravel the underlying genomic processes of convergent trait evolution. However, few animal groups have been studied in detail, and large-scale comparative genomic analyses to address toxin gene evolution are rare. Hyper-diverse hymenopterans are the most speciose group of venomous animals, but the origin of their toxin genes have been largely overlooked. We combined proteo-transcriptomics with comparative genomics compiling an up-to-date list of core bee venom proteins to investigate the origin of 11 venom genes in 30 hymenopteran genomes including two new stingless bees.
Project description:Hox proteins have been proposed to act at multiple levels within regulatory hierarchies and to directly control the expression of a plethora of target genes. However, for any specific Hox protein or tissue, very few direct in vivo-regulated target genes have been identified. Here, we have identified target genes of the Hox protein Ultrabithorax (UBX), which modifies the genetic regulatory network of the wing to generate the haltere, a modified hindwing. We used whole-genome microarrays and custom arrays including all predicted transcription factors and signaling molecules in the D. melanogaster genome to identify differentially expressed genes in wing and haltere imaginal discs. To elucidate the regulation of selected genes in more detail, we isolated cis-regulatory elements (CREs) for genes that were specifically expressed in either the wing disc or haltere disc. We demonstrate that UBX binds directly to sites in one element, and these sites are critical for activation in the haltere disc. These results indicate that haltere and metathoracic segment morphology is not achieved merely by turning off the wing and mesothoracic development programs, but rather specific genes must also be activated to form these structures. The evolution of haltere morphology involved changes in UBX-regulated target genes, both positive and negative, throughout the wing genetic regulatory network. Keywords: tissue comparison
Project description:Amongst the various different insect groups, there is remarkable diversity in the number and size of wings. However the development of the basic body plan in insects is similar to a large extent. The genes of the hox complex regulate various pathways to bring about the development or modification of different organs. Ubx, a gene of the bithorax hox complex is expressed in the third thoracic segment of insects and is known to specify the fate of wing appendage in that segment.To understand the role of Ubx and how its regulatory mechanism has evolved through the course of evolution we have compared its genome wide targets in different insect orders. The identification of regulatory pathways and the key players Ubx regulates is crucial to understand how it has controlled wing development across insect orders. Our lab has previously identified direct targets of Ubx in Drosophila using ChIP-chip (Agrawal et al, 2011). To further our knowledge on the role of regulation in development and modification of hind wing appendage we have studied the targets in the hind wings of other insects (silk moth; Lepidoptera and honeybee; Hymenoptera) and performed a comparative analysis. We have employed ChIP followed by illumina sequencing to identify the targets of Ubx in developing hind and fore wing buds of Bombyx larvae. This is a first next generation sequencing study in Lepidoptera in an attempt to understand wing development.
Project description:Amongst the various different insect groups, there is remarkable diversity in the number and size of wings. However the development of the basic body plan in insects is similar to a large extent. The genes of the hox complex regulate various pathways to bring about the development or modification of different organs. Ubx, a gene of the bithorax hox complex is expressed in the third thoracic segment of insects and is known to specify the fate of wing appendage in that segment.To understand the role of Ubx and how its regulatory mechanism has evolved through the course of evolution we have compared its genome wide targets in different insect orders. The identification of regulatory pathways and the key players Ubx regulates is crucial to understand how it has controlled wing development across insect orders. Our lab has previously identified direct targets of Ubx in Drosophila using ChIP-chip (Agrawal et al, 2011). To further our knowledge on the role of regulation in development and modification of hind wing appendage we have studied the targets in the hind wings of other insects (silk moth; Lepidoptera and honeybee; Hymenoptera) and performed a comparative analysis. We have employed ChIP followed by illumina sequencing to identify the targets of Ubx in developing hind and fore wing buds of Bombyx larvae. This is a first next generation sequencing study in Lepidoptera in an attempt to understand wing development. Chromatin Immunoprecipitation (ChIP) was used to identify genome wide targets bound by Ubx in Bombyx larval wing buds. The experiment to enrich Ubx bound regions was carried out using a Bombyx N terminal-Ubx specific poylclonal antibody raised in Rabbit and purified against a Protein A column to obtain IgG fraction. An Immunoprecipitation (IP) with Normal Rabbit IgG was used as a negative control to eliminate the regions that pertained to non specific binding to an Immunogloubulin. The normalization of both ChIP and IgG was done against sequenced input chromatin. Two replicates of single end 36 bp reads were sequenced using Ilumina for all the three conditions and for both fore and hind wing tissue samples.The peaks common to both the replicates were considered after applying a FDR cutoff.The fore wing target set was used for comparison with the hind wing targets.
Project description:The honey bee is a key pollinator in many agricultural operations as well as a model organism for studying the genetics and evolution of social behaviour. The Apis mellifera genome has been sequenced and annotated twice over, enabling proteomics and functional genomics methods for probing relevant aspects of their biology. One troubling trend that emerged from proteomic analyses is that honey bee peptide samples consistently result in lower peptide identification rates compared to other organisms. This suggests that the genome annotation can be improved, or atypical biological processes are interfering with the mass spectrometry workflow. First, we tested whether high levels of polymorphisms could explain some of the missed identifications by searching spectra against the reference proteome (OGSv3.2) versus a customized proteome of a single honey bee, but our results indicate that this contribution was minor. Likewise, error-tolerant peptide searches lead us to eliminate unexpected post-translational modifications as a major factor in missed identifications. We then used a proteogenomic approach with ~1,500 raw files to search for missing genes, new exons, and revive discarded annotations and identified over 2,000 new coding regions. These results will contribute to a more comprehensive genome annotation and facilitate continued research on this important insect.
Project description:Hox proteins are transcription factors and key regulators of segmental identity along the anterior posterior axis across all bilateral animals. Despite decades of research, mechanism by which Hox proteins select their targets and specify segmental identity remains elusive. To address this question we carried out whole genome ChIP-chip experiments to identify direct targets of Hox protein Ultrabithorax (Ubx) during haltere development in Drosophila. When mis-expressed in wing segment (T2) Ubx converts its identity to that of haltere segment (T3). We used CbxHm/+ wing discs ectopically expressing Ubx in the pouch region of discs to obtain chromatin. This helped us focus on targets of Ubx involved in pouch development without mixing with the targets involved in notum development. Polyclonal Ubx antibodies against N-terminal region (excluding homeodomain) were generated in our lab and used to pull down Ubx bound regions from CbxHm/+ wing discs. Mock DNA (No antibody) was used as control. Test Vs. Mock experiment. CbxHm/+ discs for Chromatin source. Biological replicates: 3 [Agilent two-color ChIP-on-Chip experiment,Organism: Drosophila melanogaster ,Drosophila Whole Genome ChIP-on-Chip Set 244K Microarray 1 of 2 (AMADID: 014816 and 014817)]