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Heterogeneous ribosome populations are present in Plasmodium berghei during development in its vector
Author(s) -
Thompson Joanne,
Van Spaendonk Rosalina M. L.,
Choudhuri Rangana,
Sinden Robert E.,
Janse Chris J.,
Waters Andrew P.
Publication year - 1999
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1046/j.1365-2958.1999.01167.x
Subject(s) - biology , plasmodium berghei , ribosomal rna , ribosome , gene , zygote , parasite hosting , transcription (linguistics) , rna , 18s ribosomal rna , genetics , microbiology and biotechnology , malaria , embryogenesis , immunology , linguistics , philosophy , world wide web , computer science
The genome of the rodent malaria parasite, Plasmodium berghei , contains two sets of variant ribosomal RNA (rRNA) genes, termed the A and S types, that are expressed predominantly during the vertebrate and mosquito stages of the parasite's development respectively. Using in situ hybridization, we have examined the transcriptional activity of the A‐ and S‐type rRNA genes, and the switch in expression of the ribosome populations that occurs after parasite transmission to the mosquito. By detection of precursor rRNA molecules, we show that A‐type rRNA transcription is downregulated throughout development in the mosquito, whereas the initiation of S‐type rRNA transcription is linked to the proliferative phase of the oocyst. Mature A‐type rRNA persists during development of the zygote into the ookinete/young oocyst. In contrast, mature S‐type rRNA is first detectable in young oocysts and is subsequently present at high levels during further development of oocysts and sporozoites. These results demonstrate that the switch in transcription between the A‐ and S‐type rRNA genes is developmentally regulated, taking place only as the parasite begins to proliferate in the mosquito. A‐type ribosomes are therefore not only translationally active in the early stages of development in the mosquito, but are also crucial at this phase.