High impact information on ems

• The genes ems and otd encode homeodomain proteins, suggesting that they may function as transcription factors [1].
• Here, we show that ems is a downstream gene that is transcriptionally regulated by Abd-B proteins [2].
• The empty spiracles (ems) homeo box gene is required for the development of the Drosophila larval filzkörper, which are structural specializations of the eighth abdominal segment [2].
• Genetic epistasis tests suggest that both ems and Abd-B are required in combination for the specification of the filzkörper primordia [2].
• Mutant embryos lacking ems protein have severe patterning defects in the anterior head and are missing tracheal structures, including the filzkörper, which are normally developed by the eighth abdominal segment. ems has two different spatial patterns of expression during embryogenesis [3].

Biological context of ems

• Later during embryogenesis ems is expressed in lateral regions of each segment, where the tracheal pits form and lateral neuroblasts originate, as well as in the posterior spiracles [4].
• A collection of chromosomal deficiencies were screened for their ability to modify GFP fluorescence patterns driven by Hox response elements (HREs) from wg and ems [5].
• Transgenic reporter gene lines containing mutations of the TLL binding sites demonstrate that tll directly inhibits the expression of ems in the early embryonic head and the protocerebral brain anlage [6].
• Genetical tests for the frequency of small deletions among ems-induced point mutations in Drosophila [7].

Anatomical context of ems

• During the cellular blastoderm stage ems is expressed in the developing head in a single anterior band [4].
• In ems mutants, invagination of the spiracle cells adjacent to the trachea does not occur, but more posterior cells of the spiracle invaginate normally [8].
• In the posterior brain and VNC ems is necessary for correct axonal pathfinding of specific interneurons [9].
• Hremx, the ascidian homologue of ems/emx, is expressed in the anterior and posterior-lateral epidermis but not in the central nervous system during embryogenesis [10].

Associations of ems with chemical compounds

• In addition to a homeodomain, the N-terminal portion of the predicted protein sequence is very proline-rich, whereas the C-terminus has an acidic profile consistent with the role of the ems gene product as a transcription factor [4].

Other interactions of ems

• Both ems and btd are required in partially overlapping subsets of neuroblasts of the deuterocerebrum and tritocerebrum [11].
• The early expression of the ems gene is controlled by the anterior morphogen bicoid (bcd) [4].
• We found 15 deficiencies that modify the activity of the ems HRE and 18 that modify the activity of the wg HRE [5].
• This regulation is mediated by an Abd-B-dependent ems cis-regulatory element that in early- to mid-stage embryos is activated only in the eighth abdominal segment [2].
• The ems product has the potential to induce sclerotic plates but this potential is suppressed by any of the HOM-C genes, including the labial gene, which we show to be the lowest ranking of the HOM-C hierarchy [12].

References