Maelstrom regulates spermatogenesis of the silkworm, Bombyx mori

Area of Science:

• Genetics
• Reproductive Biology
• Molecular Biology

Background:

• Spermatogenesis is vital for animal reproduction, involving numerous genes.
• Maelstrom (Mael) is known to be essential for spermatogenesis in Drosophila and mice.
• Mael's role in the piRNA pathway and oocyte development has been previously studied.

Purpose of the Study:

• To investigate the function of the Maelstrom (Mael) gene in Bombyx mori (silkworm).
• To analyze the effects of BmMael mutations on spermatogenesis and male fertility in silkworms.

Main Methods:

• Generated Bombyx mori Mael mutants using a CRISPR/Cas9 system.
• Analyzed BmMael function in silkworm ovaries and testes.
• Utilized RNA-sequencing and qRT-PCR to examine gene expression related to spermatogenesis defects.

Main Results:

• BmMael is not essential for the piRNA pathway in silkworm ovaries.
• BmMael is crucial for transposon element repression in silkworm testes.
• BmMael mutations lead to male sterility due to defects in spermatogenesis, specifically nuclear concentration arrest during elongation.
• Spermatogenesis defects are linked to disruptions in tight junctions and apoptosis.
• BmMael is not involved in the silkworm sex determination pathway.

Conclusions:

• BmMael plays a critical role in male spermatogenesis in Bombyx mori.
• The findings suggest BmMael's function in transposon repression in testes is key to male fertility.
• Understanding BmMael's function may offer new avenues for controlling lepidopteran pests.