vasa-like基因在孤雌生殖豌豆蚜發育過程之表現解析
Developmental characterization of vasa-like genes in the parthenogenetic pea aphids Acyrthosiphon pisum
Date Issued
2006
Date
2006
Author(s)
Lin, Gee-Way
DOI
zh-TW
Abstract
Germ cells are the cells that produce gametes, and they are segregated from somatic cells during early development in most animals. In the model insect Drosophila melanogaster, the specification of primordial germ cells (pole cells) depends on the maternal germline determinants localized to the egg posterior. By the formation of syncytial blastoderm, germline determinants are incorporated into pole cells with the forming cell membranes and then these cells are set to become germ cells. Unlike Drosophila, a maternal germ plasm is not identifiable in the grasshopper Schistocerca gregaria and segregated germ cells are first identified in the margin of abdomen undergoing segmentation, suggesting that germline specification may depend on induction signals released from neighboring somatic cells. I selected to study the parthenogenetic pea aphid Acyrthosiphon pisum because of its special pattern of embryogenesis - the formation of blastoderm resembles to Drosophila whilst the adding of segments in later development is similar to Schistocerca. It thus becomes an excellent model for investigating how germline specification is affected by different types of embryogenesis. Homologues of the Drosophila vasa gene are used as germline markers for this study because vasa is highly conserved in germ cells across many species across invertebrates and vertebrates. I expressed and purified fusion proteins of two pea aphid vasa homologues, pavasa1 and pavasa2, using them as antigens to induce anti-Vasa antiserum respectively. Nevertheless, immuno-staining results showed that no localized Vasa signals were identified in the germ cells. Likewise, in situ signals of localized pavasa1 and pavasa2 mRNAs were not germline positive. Fortunately I cloned pavasa3, the third vasa homologue in pea aphids, demonstrating that it was specifically expressed in germ cells. It strongly suggests that pavasa3 is a germline marker in pea aphids and it can be used as a molecular tool for studying germline development in this species.
Subjects
豌豆蚜
胚胎發育
生殖細胞
vasa
pea aphid
Acyrthosiphon pisum
germ cells
germline marker
Type
thesis
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