## 3 Discussion  
Bottom-up proteomics strategies have been applied to study the venom protein profiles of several animals, such as cindarians [31], mollusks [32], snakes [33], and ants. In fact, the compositional differences of the bullet ant _P. clavata_ crude venoms that were collected by manual gland dissection and electrical stimulation were thus elucidated [34]. In another study, the venom protein content of the ponerine ant _Pachyondyl striata_ was determined employing both in-gel (2-D electrophoresis) and in-solution digestion proteomics, resulting in the identification of 42 spots and 5 proteins [35]. Recently, several proteins were identified from the venom of the trap jaw ant _O. monticola_ by in-solution digestion venom proteomics [36]. In the present study, the experimental data of our venomic analysis, which was performed using both in-gel and in-solution-based proteomics approaches, was compared with two transcriptomic datasets of the _D. quadriceps_ venom glands, namely, (1) the predicted peptide products of 496 contigs from 800 Applied Biosystems (ABI) Prism files from the Sanger sequencing of venom gland cDNA library and (2) 18,546 assembled transcripts from more than 2,500,000 raw reads obtained from Ion Torrent RNA sequencing [23]. The majority of proteins identified by gel-based proteomics confirmed the transcriptional repertoires expressed in the _D. quadriceps_ venom gland and counterparts found in the venoms of not only other ant species, but also of wasps and honey bee, despite of their species-specific composition. For instance, in the _D. quadriceps_ venom proteome, there are toxins that shared similarity with the venom dipeptidyl peptidase-4 from the parasitic ant _Ectatemma tuberculatum_[37]; the odorant-binding protein and venom allergen 2 from the fire ant _S. [PERSON]_[7]; the phospholipase A1 2, hyaluronidase, venom allergen 3, and glucose dehydrogenase FAD from the stinging ant _P. striata_[35]; and the hyaluronidase and venom allergen 2 from the ponerine ant _[PERSON]. [PERSON]_ were identifed [36]. Moreover, the intra- and interspecific variation of venom components is a known biological phenomenon observed from arthropods to snakes [38; 39; 40] herein observed. The limit of detection for proteins in the Coomassie-stained polyacrylamide gels is approximately 50 ng with a dynamic range of up to 500 ng. Based on this, the resolution of the giant ant crude venom with one-dimensional SDS-PAGE allowed the visualization of the predominant venom polypeptide components of _D. quadriceps_ (Figure 1, Table S1). Accordingly, the venom of the giant ant _D. quadriceps_ is predominantly composed of venom allergens (major venom allergen 3 and 2/4-like), hydrolases (dipeptidyl peptidase-4, hyaluronidase, GDH, and PLA1), major royal jelly-like protein, and Kunitz-type toxin. However, considering the data from the in-solution proteomics, two additional classes of toxins of lower molecular mass should be included in the giant ant venom composition: pilosulin- and ponericin-like peptides (dinopomeratoxins) and cysteine-stabilized knottins (ICK-like). These experimental data are summarized in Tables S1 and S2. In the venom cocktail, these polypeptide components can act in combination to efficaciously exert their effect in interfering with victim and/or prey homeostasis. For instance, the venom dipeptidylpeptidase-4-like can modulate the chemotactic activity of immune cells after the sting and trigger immunoglobulin E (IgE)-mediated allergic reactions produced by basophils. Such venom enzyme is also known as allergen C (Api m 5) in the honey bee _A. mellifera_ and Ves v 3 in the common wasp _V. vulgaris_. It is also known as the major allergen of the European paper wasp _Polistes dominula_ venom [28; 41]. However, the role of glucose dehydrogenase [FAD, quinone] in the venom and venom gland of _D. quadriceps_ remains unknown. In fruit fly _D. melanogaster_, similar enzyme, UniProtKB-P18173 (DHGL_DROME), is responsible for cuticular modification during morphogenesis.