High impact information on eg

• Here we report the expression by eag RNA in Xenopus oocytes of such a channel which incorporates properties of both voltage- and ligand-gated channels [1].
• The permeability of these eag channels to potassium and calcium is dependent on voltage and cyclic AMP [1].
• Similarities in amino acid sequences of Drosophila eag and cyclic nucleotide-gated channels [2].
• Most notably, the kinetics of rat eag channel activation depend strongly on holding membrane potential [3].
• We have cloned a mammalian (rat) homologue of Drosophila ether á go-go (eag) cDNA, which encodes a distinct type of voltage activated potassium (K) channel [3].

Biological context of eg

• The zinc finger protein Eagle (Eg) is expressed in NB 7-3 just after delamination and is present in all NB 7-3 progeny until late stage 17 [4].
• The derived Drosophila and rat eag polypeptides share > 670 amino acids, with a sequence identity of 61%, exhibiting a high degree of similarity at the N-terminus, the hydrophobic core including the pore forming P region and a potential cyclic nucleotide binding site [3].
• These behavioral and synaptic defects are not simply additive in animals carrying both an eag mutation and a transgene for a protein kinase inhibitor, raising the possibility that the phenotypes share a common pathway [5].
• Similar defects in both synaptic transmission and associative learning are produced in Drosophila melanogaster by inhibition of calcium/calmodulin-dependent protein kinase II and mutations in the potassium channel subunit gene eag [5].
• Genomic Southern analysis indicates that Manduca contains a single member of the eag subfamily per haploid genome [6].

Anatomical context of eg

• Identification of genes controlling germ cell migration and embryonic gonad formation in Drosophila [7].
• Embryonic gonad formation involves intimate contact between germ cells and specialized somatic cells along with the complex morphogenetic movements necessary to create proper gonad architecture [8].
• Germline stem cells in the Drosophila ovary descend from pole cells in the anterior region of the embryonic gonad [9].
• Many of these genes are involved in the development of gonadal mesoderm, the tissue that associates with germ cells to form the embryonic gonad [7].
• We find that in the hyperexcitable mutant eag Sh, there are dramatic ultrastructural alterations at synaptic boutons [10].

Associations of eg with chemical compounds

• eagle, a member of the steroid receptor gene superfamily, is expressed in a subset of neuroblasts and regulates the fate of their putative progeny in the Drosophila CNS [11].
• Four independent mutant eag alleles exhibited reduced antennal sensitivity to a subset of nine odorants, all having short aliphatic side chains: ethyl butyrate (EB), propionic acid, 2-butanone, and ethyl acetate [12].
• eagle is required for the specification of serotonin neurons and other neuroblast 7-3 progeny in the Drosophila CNS [13].
• Significantly fewer eag antennal neurons responded to EB compared with control neurons; the proportion sensitive to 2-heptanone was similar to controls [12].
• Three independent mutant alleles of eag revealed reduced antennal responsiveness in adult flies to a subset of odorants, all having short aliphatic side chains: ethyl butyrate (EB), propionic acid, 2-butanone and ethyl acetate (manuscript submitted) [14].

Regulatory relationships of eg

• We have found that Abdominal-B (ABD-B) is expressed in a sexually dimorphic manner in the embryonic gonad [15].

Other interactions of eg

• The differentiation of the serotonergic neurons in the Drosophila ventral nerve cord depends on the combined function of the zinc finger proteins Eagle and Huckebein [4].
• In a pilot experiment, we generated a cDNA library from purified embryonic gonad and identified a novel germline-specific gene, RpL22-like [16].
• 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGCoAr) provides attractive cues to Drosophila germ cells, guiding them toward the embryonic gonad [17].

References