Isolation of mixis-related genes from the rotifer Brachionus plicatilis using subtractive hybridization

Abstract

The monogonont rotifer Brachionus plicatilis produces resting eggs through sexual reproduction (mixis), which is affected by external and internal factors. We collected resting eggs from rotifers cultured at 15 and 25°C and hatched them with and without 14-day dormancy in the dark. Stem females hatched from both conditions were further cultured at 15, 20 and 25°C. We obtained two phenotypes, one with high mixis (more than 50%), which was hatched from resting eggs formed at 15°C without dormancy, and another in which sexual reproduction occurred at 25°C and resting eggs were formed at 15°C with a 14-day dormancy. In the latter phenotype, mictic females appeared at 15°C, but not at 25°C. Using subtractive hybridization, we isolated one gene from the latter phenotype of females that had no significant similarity to known genes in BLAST searches. We propose that this gene is unique to rotifer mictic reproduction. Ongoing characterization of this gene attempts understand its role in mixis.