A single female-specific piRNA is the primary determiner of sex in the silkworm

@article{Kiuchi2014ASF,
  title={A single female-specific piRNA is the primary determiner of sex in the silkworm},
  author={Takashi Kiuchi and Hikaru Koga and Munetaka Kawamoto and Keisuke Shoji and Hiroki Sakai and Yuji Arai and Genki Ishihara and Shinpei Kawaoka and Sumio Sugano and T. Shimada and Yutaka Suzuki and Masataka G. Suzuki and Susumu Katsuma},
  journal={Nature},
  year={2014},
  volume={509},
  pages={633-636}
}
The silkworm Bombyx mori uses a WZ sex determination system that is analogous to the one found in birds and some reptiles. In this system, males have two Z sex chromosomes, whereas females have Z and W sex chromosomes. The silkworm W chromosome has a dominant role in female determination, suggesting the existence of a dominant feminizing gene in this chromosome. However, the W chromosome is almost fully occupied by transposable element sequences, and no functional protein-coding gene has been… 
Guardian small RNAs and sex determination
TLDR
The results revealed that female-specific piRNA precursors, which were named Fem and Masc, are transcribed from the sex-determining region of the W chromosome at the early embryonic stage and are processed into a single mature piRNA (Fem piRNA).
Non-coding RNA: Small RNA determines silkworm sex
TLDR
The researchers identified a target gene of Fem-derived piRNA on the Z chromosome, which they called Masc, and found that Silencing of Masc is needed for the production of female-specific isoforms of Bmdsx in female embryos, whereas in male embryos the Masc protein regulates dosage compensation and masculinization.
Transcriptome analysis in the silkworm Bombyx mori overexpressing piRNA-resistant Masculinizer gene
TLDR
Fourteen genes were differentially expressed between Masc-R-overexpressing and control neonate larvae in both sexes, suggesting Masc functions other than dosage compensation and masculinization, and excessive Masc expression strengthens neither dosage compensation nor maleness in males.
A conserved role of the duplicated Masculinizer gene in sex determination of the Mediterranean flour moth, Ephestia kuehniella
TLDR
It is suggested that the C-terminal proline-rich domain, which is identified in all functionally confirmed Masc proteins, in conjunction with the masculinizing domain, is important for transcriptional regulation of sex determination in Lepidoptera.
Bombyx mori histone methyltransferase BmAsh2 is essential for silkworm piRNA-mediated sex determination
TLDR
It is shown here that the silkworm PIWI protein BmSiwi, but not BmAgo3, is essential for silkworm sex determination, and the first evidence that the HMT, BmAsh2, plays key roles in silkworm piRNA-mediated sex determination is provided.
Transgenic Expression of the piRNA-Resistant Masculinizer Gene Induces Female-Specific Lethality and Partial Female-to-Male Sex Reversal in the Silkworm, Bombyx mori
TLDR
The results strongly suggest that Masc is an important regulatory gene of maleness in B. mori.
Structural analysis of spontaneous Z-W translocations in the silkworm, Bombyx mori
TLDR
The W-specific sequences were used to characterize four aberrant sex chromosomes arising from spontaneous translocations between T(W;Z)+ and T(Z;2)Y chromosomes, and molecular evidence was obtained that the breakpoints of the translocation events reside within the W-chromosomal region of the T(w;W)+ chromosome.
A CCCH zinc finger gene regulates doublesex alternative splicing and male development in Bombyx mori
TLDR
The data reveals that Bmznf-2 plays an indispensable role in silkworm male sexual differentiation, and shows that male mutants show delayed developmental timing, smaller body sizes of larvae and malformation of moth wings.
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