title: Transcriptome analysis of cyst formation in Rhodospirillum centenum reveals large global changes in expression during cyst development.
abstract: BACKGROUND
  Rhodospirillum centenum is a photosynthetic member of the Gram-negative Azospirillum clade members of which exhibit a complex developmental life-cycle featuring morphologically distinct cell types. Under periods of nutrient deprivation, replicative vegetative cells differentiate into metabolically dormant cysts that survive harsh environmental stresses such as desiccation. Encystment involves a multi-stage developmental process that includes the rounding of cells, production of large intracellular storage granules of poly-hydroxybutyrate (PHB) and the excretion of a protective exopolysaccharide coating that envelops dormant cysts.
  
  
  RESULTS
  To study the process of cyst development, we performed RNA-seq studies on cells that were induced to undergo cyst development. To assay for temporal changes in gene expression, RNA was extracted at 4, 24, 48, 72, 96 hours during development and subjected to deep sequence analysis. These results show that 812 genes exhibit log2 ≥ 1.5-fold changes in expression over a 96 hour cyst induction period demonstrating large global changes in gene expression during cyst development.
  
  
  CONCLUSIONS
  Notable changes in expression occurred in numerous genes involved in cell wall and lipid biosynthesis, metabolic enzymes, and numerous regulatory genes such as histidine kinases and transcription factors. Many genes involved in protein synthesis and DNA replication were also significantly reduced during late stages of cyst development. Genes previously identified by genetic screens as being critical for cyst development also exhibited changes of expression during cyst induction. This study provides the first transcriptome profile of global changes in gene expression that occur during development of cysts in a Gram-negative species.
authors.affiliation: Molecular and Cellular Biochemistry Department, Indiana University, Bloomington, IN, 47405, USA. Dong3@indiana.edu.
authors.forename: Qian
authors.initials: Q
authors.lastname: Dong
authors.affiliation: Molecular and Cellular Biochemistry Department, Indiana University, Bloomington, IN, 47405, USA. bauer@indiana.edu.
authors.forename: Carl E
authors.initials: CE
authors.lastname: Bauer
mesh_terms: D000596:Amino Acids / Q000378:metabolism; D002473:Cell Wall / Q000235:genetics / Q000378:metabolism; D004734:Energy Metabolism / Q000235:genetics; D050356:Lipid Metabolism / Q000235:genetics; D042182:Rhodospirillum centenum / Q000235:genetics* / Q000378:metabolism; D017423:Sequence Analysis, RNA; D015398:Signal Transduction / Q000235:genetics; D059467:Transcriptome
chemical_list: D000596:Amino Acids