Studies on the P-element piRNAs associated with hybrid dysgenesis in Drosophila melanogaster

キイロショウジョウバエにおけるP因子piRNAと雑種交配不全との関連の研究

2018-09-25

2018-09-25

P-element transposition in the genome causes P-M hybrid dysgenesis in Drosophila melanogaster. Maternally deposited piRNAs suppress P-element transposition in the P-strain progeny, linking to P-M phenotypes. However, little is known about the extent to which piRNAs are involved in the P-M hybrid dysgenesis in M′ and Q strains, which show different abilities to regulate the P elements from P strains. The defect of suppressing P-element transposition when used as a mother is called P susceptibility, which is low for P and Q strains and high for M and M’ strains. P-strain males have a high ability to mobilize P elements in their progeny (high P inducibility), while M’-, Q- and M-strain males have a low ability. In chapter I, to elucidate the molecular basis of P susceptibility, I analyzed the piRNA levels of P elements in the F1 progeny between males of a P strain and nine-line females of M′ or Q strains (M′ or Q progenies). As a result, it was proved that the M′ progenies, which showed the hybrid dysgenesis phenotype, were characterized by a lower abundance of P-element piRNAs in both young ovaries and embryonic bodies. In chapter II, to reveal the molecular basis of P inducibility, I investigated the genomic constitution and P-element piRNA production, using the F1 hybrid between females of an M strain and four-line males of M′ or Q strains (M′ or Q hybrids). As a result, it was showed that the young ovaries of Q hybrids produced higher levels of piRNAs from P element inserted in piRNA clusters. And amount of those piRNA was linked to gonadal dysgenesis in both F1 and F2. Our results are consistent with an idea that the level of P-element piRNAs is a determinant for dividing strain types between M′ and Q. Additionally, I showed that various expressions of suppressors influenced by the genomic constitution of the paternal P elements lead to phenotypic variation in the progeny.

博士（学術）

京都工芸繊維大学

14303甲第888号

http://hdl.handle.net/10212/2490

eng

ETD

2

Thesis or Dissertation

Thesis