Studies of two gene activities required for early Drosophila embryogenesis

• Main Authors: Chen, Yueh-Jung, 陳月茸
• Other Authors: Liaw, Gwo-Jen
• Format: Others
• Language: en_US
• Published: 2002
• Online Access: http://ndltd.ncl.edu.tw/handle/66090295041811863565

博士 === 國立陽明大學 === 遺傳學研究所 === 90 === Drosophila early embryogenesis is complicated and requires many maternal genes (which are provided by nurse cells during oogenesis) to participate in the developmental process. In this thesis, I characterized the functions of two maternal genes, tramtrack69 (ttk69) and dtlk (drosophila tousled-like-kinase). In the chapter II ( the first part of this thesis), TTK69 was identified to be required for the early (before the end of stage 4) repression of tll transcription. The activated Torso (TOR) receptor tyrosine kinase pathway activates tailless (tll) expression by a relief-of-repression mechanism. Various lines of evidence have suggested that multiple factors are required for this repression. TTK69 was shown to bind to two sites within tll cic-regulatory DNA, TC2 and TC5. In embryos lacking maternal ttk69 activity, the expression of both endogenous and lacZ driven by the tll minimal regulatory region (tll-MRR) are expanded. Furthermore, in the wild-type embryos, the tll-MRR mutated in TC5 drives uniform lacZ expression before late stage 4. In addition, in vitro, TTK69 would be directly phosphorylated by MAPK. These results suggest TTK69 directly acts on promoter to repress expression of tll and its repressive activity was modulated by TOR pathway, which activates tll at the two terminal domains of embryos. In chapter III (the second part of this thesis), I characterized a Drosophila hshpk homologue, Drosophila tousled-like-kinase (dtlk) encoding an evolutionally conserved serine/threonine kinase. First, regard to the expression patter of dtlk, two alternative transcripts (dtlk-l and dtlk-s) were predicted by the GradFly and have different distribution patterns during embryogenesis. dtlk-l is specifically detected in pole cells at early stages; dtlk-s is ubiquitous at early stages except pole cells and restricted in brain lobes and CNS (central nervous system) at late stages. Second, about the ectopic expression, ey>dtlk-l results in a small-eye phenotype and GMR>dtlk-l results in glass-eye phenotype. Third, phenotypic analysis of dtlk mutants, the deficiency and P-element insertion lines, revealed that DTLK perhaps involved in regulation of chromosomal segregation.