title: Regulation of Plasmodium yoelii oocyst development by strain- and stage-specific small-subunit rRNA.
abstract: One unique feature of malaria parasites is the differential transcription of structurally distinct rRNA (rRNA) genes at different developmental stages: the A-type genes are transcribed mainly in asexual stages, whereas the S-type genes are expressed mostly in sexual or mosquito stages. Conclusive functional evidence of different rRNAs in regulating stage-specific parasite development, however, is still absent. Here we performed genetic crosses of Plasmodium yoelii parasites with one parent having an oocyst development defect (ODD) phenotype and another producing normal oocysts to identify the gene(s) contributing to the ODD. The parent with ODD--characterized as having small oocysts and lacking infective sporozoites--was obtained after introduction of a plasmid with a green fluorescent protein gene into the parasite genome and subsequent passages in mice. Quantitative trait locus analysis of genome-wide microsatellite genotypes of 48 progeny from the crosses linked an ~200-kb segment on chromosome 6 containing one of the S-type genes (D-type small subunit rRNA gene [D-ssu]) to the ODD. Fine mapping of the plasmid integration site, gene expression pattern, and gene knockout experiments demonstrated that disruption of the D-ssu gene caused the ODD phenotype. Interestingly, introduction of the D-ssu gene into the same parasite strain (self), but not into a different subspecies, significantly affected or completely ablated oocyst development, suggesting a stage- and subspecies (strain)-specific regulation of oocyst development by D-ssu. This study demonstrates that P. yoelii D-ssu is essential for normal oocyst and sporozoite development and that variation in the D-ssu sequence can have dramatic effects on parasite development.
  
  
  OBJECTIVE
  Malaria parasites are the only known organisms that express structurally distinct rRNA genes at different developmental stages. The differential expression of these genes suggests that they play unique roles during the complex life cycle of the parasites. Conclusive functional proof of different rRNAs in regulating parasite development, however, is still absent or controversial. Here we functionally demonstrate for the first time that a stage-specifically expressed D-type small-subunit rRNA gene (D-ssu) is essential for oocyst development of the malaria parasite Plasmodium yoelii in the mosquito. This study also shows that variations in D-ssu sequence and/or the timing of transcription may have profound effects on parasite oocyst development. The results show that in addition to protein translation, rRNAs of malaria parasites also regulate parasite development and differentiation in a strain-specific manner, which can be explored for controlling parasite transmission.
authors.forename: Yanwei
authors.initials: Y
authors.lastname: Qi
authors.forename: Feng
authors.initials: F
authors.lastname: Zhu
authors.affiliation: Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health (NIH), Bethesda, Maryland, USA.
authors.forename: Richard T
authors.initials: RT
authors.lastname: Eastman
authors.affiliation: Department of Pathogenic Biology, The Third Military Medical University, Chongqing, People's Republic of China.
authors.forename: Young
authors.initials: Y
authors.lastname: Fu
authors.affiliation: Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health (NIH), Bethesda, Maryland, USA.
authors.forename: Martine
authors.initials: M
authors.lastname: Zilversmit
authors.forename: Sittiporn
authors.initials: S
authors.lastname: Pattaradilokrat
authors.affiliation: State Key Laboratory of Cellular Stress Biology, Innovation Center for Cell Signaling Network, School of Life Sciences, Xiamen University, Xiamen, Fujian, People's Republic of China.
authors.forename: Lingxian
authors.initials: L
authors.lastname: Hong
authors.affiliation: State Key Laboratory of Cellular Stress Biology, Innovation Center for Cell Signaling Network, School of Life Sciences, Xiamen University, Xiamen, Fujian, People's Republic of China.
authors.forename: Shengfa
authors.initials: S
authors.lastname: Liu
authors.affiliation: Department of Pathogen Biology, The Second Military Medical University, Shanghai, China.
authors.forename: Thomas F
authors.initials: TF
authors.lastname: McCutchan
authors.affiliation: Department of Pathogen Biology, The Second Military Medical University, Shanghai, China.
authors.forename: Weiqing
authors.initials: W
authors.lastname: Pan
authors.affiliation: Department of Pathogenic Biology, The Third Military Medical University, Chongqing, People's Republic of China.
authors.forename: Wenyue
authors.initials: W
authors.lastname: Xu
authors.affiliation: State Key Laboratory of Cellular Stress Biology, Innovation Center for Cell Signaling Network, School of Life Sciences, Xiamen University, Xiamen, Fujian, People's Republic of China fushenghster@gmail.com jianli_204@xmu.edu.cn xsu@niaid.nih.gov.
authors.forename: Jian
authors.initials: J
authors.lastname: Li
authors.affiliation: Department of Pathogenic Biology, The Third Military Medical University, Chongqing, People's Republic of China fushenghster@gmail.com jianli_204@xmu.edu.cn xsu@niaid.nih.gov.
authors.forename: Fusheng
authors.initials: F
authors.lastname: Huang
authors.affiliation: fushenghster@gmail.com jianli_204@xmu.edu.cn xsu@niaid.nih.gov.
authors.forename: Xin-zhuan
authors.initials: XZ
authors.lastname: Su
mesh_terms: D000818:Animals; D002874:Chromosome Mapping; D003433:Crosses, Genetic; D018507:Gene Expression Regulation, Developmental; D055786:Gene Knockout Techniques; D051379:Mice; D018895:Microsatellite Repeats; D033661:Oocysts / Q000254:growth & development*; D010967:Plasmodium yoelii / Q000235:genetics* / Q000254:growth & development*; D040641:Quantitative Trait Loci; D012337:RNA, Ribosomal, 18S / Q000235:genetics*; D011995:Recombination, Genetic
chemical_list: D012337:RNA, Ribosomal, 18S