Ectopic expression of aphid genes in fruit flies lead has led to the discovery of sequences critical to the localization of germline protein Vasa to the germ plasm. Germ plasm , the cytoplasm of germ cells, is enriched with germline determinants for the development of germ cells. If germ plasm is maternally supplied, it is usually assembled in a subcellular region within the oocyte and then inherited by the newly laid eggs. Soon after cellularization, embryonic cells that incorporate germ plasm will become the primordial germ cells. By contrast, if formation of the germ plasm occurs zygotically after fertilization, synthesis of the germline determinants within a small population of cells is initiated by inductive signals released from neighboring somatic cells. Existing records show that most animals do not own possess a maternal germ plasm, and a recent study shows that both mice and crickets both share use bone morphogenetic protein (BMP) signaling to induce germline specification. Accordingly, itThis suggests that among animal phyla , the signal induction is a more prevalent and ancestral mode of for germline specification than that specification driven by the germ plasm among animal phyla. Before the identification of a maternal germ plasm in the pea aphid Acyrthosiphon pisum, a hemipteran insect belonging to the Hemimetabola, the germ-plasm- driven mode was regarded as a privilege trait only seen in highly derived insects belonging to the Holometabola. For example, during mid-oogenesis in the fruit fly Drosophila melanogaster, oskar (osk) mRNA and Osk protein are restricted to the posterior pole of the oocyte, acting as “molecular anchors” to restrict the circulation of other germline determinants circulating to the posterior region. Nonetheless, homologous sequences of osk cannot be identified in the genome of A. pisum, suggesting that it chooses uses non-osk molecules to attract other germline determinants to form the germ plasm. Regardless of the presence or absence of osk in flies and aphids, the conserved germline marker Vasa (Vas) is specifically localized to the maternal germ plasm of both insects. In order toTo understand whether aphid Vas (ApVas1), like Drosophila Vas (DmVas), preserves sequence for being localized by Osk, Professor Chun-che Chang—an evolutionary and developmental (evo-devo) biologist developmental geneticist in the Department of Entomology at the National Taiwan University (NTU)—proposed to express ApVas1 in the Drosophila oocytes. This idea, abbreviated as “AID (aphid genes expressed in Drosophila), was soon approved by Dr. Ming-der Lin, an alumnus of NTU and a junior faculty member working on Drosophila oogenesis affiliated to with the Department of Molecular Biology and Human Genetics at the Tzu Chi University. Laboratories ofThe Chang and Lin laboratories collaborated to generate the transgenic flies containing the Apvas1 sequence, aiming to analyze whether ApVas1 could be localized to the germ plasm in the posterior region of the developing oocytes. At firstNot totally unexpectedly, the universal expression of ApVas1, though not totally unexpected, was initially detected in throughout the Drosophila oocytes, indicating that ApVas1 lacks sequences to interact with Osk. Given that both ApVas1 and DmVas are RNA helicases containing conserved DEXDc and HELICc domains, systematic “domain swapping” experiments were then carried out to pinpoint sequences in DmVas that could direct ApVas1 and DmVas itself to the posterior germ plasm. The carpet thorough survey led to a remarkable finding: the HELICc domain of DmVas, either when being linked to ApVas1 or alone, was essential to for posterior localization; moreover, glutamine (Gln) 527 in the HELICc domain of DmVas was found to be critical to for the interaction between Vas and Osk. A corresponding residue of corresponding to Gln527, which is present in the HELICc domains of grasshopper Vas protein rather inbut not in those of aphids, crickets, and mice, may explain why only grasshopper Vas could be restricted to the posterior germ plasm . Published results show that segregation of germ cells in the grasshopper Schistocerca gregaria initiates is initiated during mid- embryogenesis via signal induction rather than being driven by a maternal germ plasm, implicating indicating that the conserved Gln527 residue has existed in some insect Vas proteins long before the presence existence of Osk in Drosophila. The results mentioned above have been published in Scientific Reports, an online and open- access online journal from the publishers of Nature, in September 2015. From the evolutionary and developmental evo-devo study of insect Vas proteins to the discovery of sequences indispensable to the interaction with Osk, members of both the Chang and Lin laboratories felt excited by the unpredicted yet fruitful outcome. Their findings shed light on the evolution of germline specification in insects and on Osk/Vas-dependent germ- plasm assembly in Drosophila. The They expect that the AID project, they expect, can will evolve to facilitate the functional exploration of more additional germline and developmental genes in rising insect models by with the “aid” from of the powerful approaches of used in Drosophila genetics. Szu-Chieh Wang, Hao-Jen Hsu, Gee-way Lin, Ting-Fang Wang, Chun-che Chang & Ming-Der Lin. Germ plasm localisation of the HELICc of Vasa in Drosophila: analysis of domain sufficiency and amino acids critical for localisation. Scientific Reports 5:14703. doi: 10.1038/srep14703 (2015). Reference Szu-Chieh Wang, Hao-Jen Hsu, Gee-way Lin, Ting-Fang Wang, Chun-che Chang and Ming-Der Lin. (2015).Germ plasm localisation of the HELICc of Vasa in Drosophila: analysis of domain sufficiency and amino acids critical for localisation. Scientific Reports, 5:14703. DOI: 10.1038/ srep14703 Professor Chun-che Chang Department & Graduate Institute of Entomology chunche@ntu.edu.tw