Transcriptome analysis of the binucleate ciliate Tetrahymena thermophila cells after mating and re-feeding.

During macronuclear development the five germline chromosomes undergo massive rearrangement, and the entire epigenome is remodeled from an obligate heterochromatic to obligate euchromatic state. The ~180 unique macronuclear chromosomes undergo two development waves of endo-reduplication to achieve a final copy number of ~45C, while the 21 kb rDNA minichromosome is amplified to ~9000C. The first period (endoreplication phase I) involves two rounds of DNA replication and generates an 8 C macronucleus (6–18 h after mating). Upon re-feeding, a second re-replication period (endoreplication phase II) is initiated generating a macronuclear DNA content of 32–64 C. This study focused on RNA expression profile of cell in endoreplication phase II. Cell of different mating types were induced to conjugate by mixng after overnight starvation (19 hours). RNA was isolated at 2 hours after refeeding cells that were mated for 24 hours (endoreplication phase II). Non-mating cells that were starved for 24 hours and then refed for 2 hours were used as control (vegetative cell cycle, early S phase).