scholarly journals Regulation of Plasmodium yoelii Oocyst Development by Strain- and Stage-Specific Small-Subunit rRNA

mBio ◽  
2015 ◽  
Vol 6 (2) ◽  
Author(s):  
Yanwei Qi ◽  
Feng Zhu ◽  
Richard T. Eastman ◽  
Young Fu ◽  
Martine Zilversmit ◽  
...  
Keyword(s):  
Developmental Stages ◽  
Small Subunit ◽  
Plasmodium Yoelii ◽  
Rrna Genes ◽  
Parasite Development ◽  
Rrna Gene ◽  
Small Subunit Rrna ◽  
Malaria Parasites ◽  
Content Type ◽  
Small Subunit Rrna Gene

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. IMPORTANCE 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.

Redescriptions of three trachelocercid ciliates (Protista, Ciliophora, Karyorelictea), with notes on their phylogeny based on small subunit rRNA gene sequences

2013 ◽  
Vol 63 (Pt_9) ◽  
pp. 3506-3514 ◽  
Author(s):  
Ying Yan ◽  
Yuan Xu ◽  
Zhenzhen Yi ◽  
Alan Warren
Keyword(s):  
Sequence Data ◽  
Phylogenetic Analyses ◽  
Small Subunit ◽  
Rrna Genes ◽  
Rrna Gene ◽  
Ssu Rrna ◽  
Small Subunit Rrna ◽  
Small Subunit Rrna Gene ◽  
Ssu Rrna Gene Sequence ◽  
First Time

Three trachelocercid ciliates, Kovalevaia sulcata (Kovaleva, 1966) Foissner, 1997, Trachelocerca sagitta (Müller, 1786) Ehrenberg, 1840 and Trachelocerca ditis (Wright, 1982) Foissner, 1996, isolated from two coastal habitats at Qingdao, China, were investigated using live observation and silver impregnation methods. Data on their infraciliature and morphology are supplied. The small subunit rRNA (SSU rRNA) genes of K. sulcata and Trachelocerca sagitta were sequenced for the first time. Phylogenetic analyses based on SSU rRNA gene sequence data indicate that both organisms, and the previously sequenced Trachelocerca ditis, are located within the trachelocercid assemblage and that K. sulcata is sister to an unidentified taxon forming a clade that is basal to the core trachelocercids.

Phenotypic effects of targeted mutations in the small subunit rRNA gene of Tetrahymena thermophila

1993 ◽  
Vol 13 (8) ◽  
pp. 4814-4825
Author(s):  
R Sweeney ◽  
L Chen ◽  
M C Yao
Keyword(s):  
Tertiary Structure ◽  
Tetrahymena Thermophila ◽  
Ribosomal Subunit ◽  
Small Subunit ◽  
Rrna Genes ◽  
Rrna Gene ◽  
Small Subunit Rrna ◽  
Variable Regions ◽  
Small Subunit Rrna Gene

Tetrahymena thermophila is an ideal organism with which to study functional aspects of the rRNAs in vivo since the somatic rRNA genes of T. thermophila can be totally replaced by cloned copies introduced via microinjection. In this study, we made small insertions into seven sites within the small subunit rRNA gene and observed their phenotypic effects on transformed cells. Two mutated genes coding for rRNA (rDNAs), both of which bear insertions in highly conserved sequences, failed to transform and are therefore believed to produce nonfunctional rRNAs. Three other altered rDNAs produce functional rRNAs that can substitute for most or all of the cellular rRNA. Two of these bear insertions in highly variable regions, and, surprisingly, the other has an insertion in a region that is well conserved for both sequence and secondary structure among eucaryotes. In addition, two other insertions appear to destabilize rRNAs that contain them. Our findings make predictions concerning the positions of some of these sites within the tertiary structure of the small ribosomal subunit and thus serve as an in vivo test of the existing tertiary structure models for the small subunit rRNA. Our results are in good agreement with expectations based on sequence comparison and in vitro work.

scholarly journals Phenotypic effects of targeted mutations in the small subunit rRNA gene of Tetrahymena thermophila.

1993 ◽  
Vol 13 (8) ◽  
pp. 4814-4825 ◽  
Author(s):  
R Sweeney ◽  
L Chen ◽  
M C Yao
Keyword(s):  
Tertiary Structure ◽  
Tetrahymena Thermophila ◽  
Ribosomal Subunit ◽  
Small Subunit ◽  
Rrna Genes ◽  
Rrna Gene ◽  
Small Subunit Rrna ◽  
Variable Regions ◽  
Small Subunit Rrna Gene

Tetrahymena thermophila is an ideal organism with which to study functional aspects of the rRNAs in vivo since the somatic rRNA genes of T. thermophila can be totally replaced by cloned copies introduced via microinjection. In this study, we made small insertions into seven sites within the small subunit rRNA gene and observed their phenotypic effects on transformed cells. Two mutated genes coding for rRNA (rDNAs), both of which bear insertions in highly conserved sequences, failed to transform and are therefore believed to produce nonfunctional rRNAs. Three other altered rDNAs produce functional rRNAs that can substitute for most or all of the cellular rRNA. Two of these bear insertions in highly variable regions, and, surprisingly, the other has an insertion in a region that is well conserved for both sequence and secondary structure among eucaryotes. In addition, two other insertions appear to destabilize rRNAs that contain them. Our findings make predictions concerning the positions of some of these sites within the tertiary structure of the small ribosomal subunit and thus serve as an in vivo test of the existing tertiary structure models for the small subunit rRNA. Our results are in good agreement with expectations based on sequence comparison and in vitro work.

Identification of the four species of human malaria parasites by nested PCR that targets variant sequences in the small subunit rRNA gene

1997 ◽  
Vol 46 (2) ◽  
pp. 91-95 ◽  
Author(s):  
Masatsugu Kimura ◽  
Osamu Kaneko ◽  
Qing Liu ◽  
Mian Zhou ◽  
Fumihiko Kawamoto ◽  
...  
Keyword(s):  
Nested Pcr ◽  
Small Subunit ◽  
Rrna Gene ◽  
Small Subunit Rrna ◽  
Malaria Parasites ◽  
Human Malaria ◽  
Small Subunit Rrna Gene

scholarly journals Specificity of Associations between Bacteria and the Coral Pocillopora meandrina during Early Development

2012 ◽  
Vol 78 (20) ◽  
pp. 7467-7475 ◽  
Author(s):  
Amy Apprill ◽  
Heather Q. Marlow ◽  
Mark Q. Martindale ◽  
Michael S. Rappé
Keyword(s):  
Small Subunit ◽  
Rrna Genes ◽  
Polymorphism Analysis ◽  
Roseobacter Clade ◽  
Small Subunit Rrna ◽  
Content Type ◽  
Sterile Seawater ◽  
Show Evidence ◽  
Coral Health

ABSTRACTRelationships between corals and specific bacterial associates are thought to play an important role in coral health. In this study, the specificity of bacteria associating with the coralPocillopora meandrinawas investigated by exposing coral embryos to various strains of cultured marine bacteria, sterile seawater, or raw seawater and examining the identity, density, and location of incorporated cells. The isolates utilized in this experiment included members of the Roseobacter and SAR11 clades of theAlphaproteobacteria, aPseudoalteromonasspecies of theGammaproteobacteria, and aSynechococcusspecies of theCyanobacteriaphylum. Based on terminal restriction fragment length polymorphism analysis of small-subunit rRNA genes, similarities in bacterial communities associated with 170-h-old planulae were observed regardless of treatment, suggesting that bacteria may have been externally associated from the outset of the experiment. Microscopic examination ofP. meandrinaplanulae by fluorescencein situhybridization with bacterial and Roseobacter clade-specific oligonucleotide probes revealed differences in the densities and locations of planulae-associated cells. Planulae exposed to either raw seawater or strains ofPseudoalteromonasand Roseobacter harbored the highest densities of internally associated cells, of which 20 to 100% belonged to the Roseobacter clade. Planulae exposed to sterile seawater or strains of the SAR11 clade andSynechococcusdid not show evidence of prominent bacterial associations. Additional analysis of the raw-seawater-exposed planulae via electron microscopy confirmed the presence of internally associated prokaryotic cells, as well as virus-like particles. These results suggest that the availability of specific microorganisms may be an important factor in the establishment of coral-bacterial relationships.

Phylogenetic analysis of Blastocystis isolates from different hosts based on the comparison of small-subunit rRNA gene sequences

2003 ◽  
Vol 126 (1) ◽  
pp. 119-123 ◽  
Author(s):  
Christophe Noël ◽  
Corinne Peyronnet ◽  
Delphine Gerbod ◽  
Virginia P Edgcomb ◽  
Pilar Delgado-Viscogliosi ◽  
...  
Keyword(s):  
Phylogenetic Analysis ◽  
Small Subunit ◽  
Rrna Gene ◽  
Small Subunit Rrna ◽  
Gene Sequences ◽  
Small Subunit Rrna Gene

Genetic interrelationships of proteolyticClostridium botulinum types A, B, and F and other members of theClostridium botulinum complex as revealed by small-subunit rRNA gene sequences

1994 ◽  
Vol 64 (3-4) ◽  
pp. 273-283 ◽  
Author(s):  
R. A. Hutson ◽  
D. E. Thompson ◽  
P. A. Lawson ◽  
R. P. Schocken-Itturino ◽  
E. C. B�ttger ◽  
...  
Keyword(s):  
Small Subunit ◽  
Rrna Gene ◽  
Small Subunit Rrna ◽  
Gene Sequences ◽  
Small Subunit Rrna Gene

Free-living nematodes associated with pine cones of Pinus thunbergii and P. taeda at Japanese coastal and inland forest sites

Nematology ◽  
2019 ◽  
Vol 21 (4) ◽  
pp. 389-400 ◽  
Author(s):  
Yudai Kitagami ◽  
Natsumi Kanzaki ◽  
Toko Tanikawa ◽  
Yosuke Matsuda
Keyword(s):  
Gene Sequence ◽  
Small Subunit ◽  
Pinus Thunbergii ◽  
Rrna Gene ◽  
Small Subunit Rrna ◽  
Free Living ◽  
Small Subunit Rrna Gene ◽  
Forest Sites ◽  
High Bootstrap ◽  
Pine Cones

Summary We surveyed the distribution of nematodes in 56 cones of Pinus thunbergii collected from both live branches and on the forest floor in three coastal and inland habitats and in 11 cones of P. taeda collected at different heights. We identified 47 nematodes to family or genera by analysis of an 18S small subunit rRNA gene sequence. The frequencies of occurrence of free-living cone nematodes were 97% in coastal P. thunbergii, 92% in inland P. thunbergii, and 82% in P. taeda. Phylogenetic analysis assigned the nematodes to four clades with high bootstrap values. Nine sequences that were found only in cones on live branches were clustered with Panagrobelus stammeri and an unknown Panagrobelus sp. Our results imply that nematodes are commonly associated with cones in pine forest ecosystems and that a capacity for anhydrobiosis may be a key to surviving above-ground.

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