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African trypanosomes that cycle between mammalian hosts and the tsetse fly vector must be poised to survive in different environments. The control of stage-specific gene expression is undoubtedly one of the keys to successful adaptation, but no regulatory elements have been defined to date. Procyclins (also known as procyclic acidic repetitive proteins) are(More)
The procyclin-associated genes (PAGs) of Trypanosoma brucei are located downstream of tandemly repeated procyclin genes and belong to the same alpha-amanitin-resistant polycistronic transcription units. In procyclic form trypanosomes the PAG 1 pre-mRNA is alternatively spliced to give rise to three transcripts of 2.7 kb, 1.8 kb and 1.3 kb. The two larger(More)
Infection of breeding hens with Eimeria maxima induces production of Eimeria-specific IgG antibodies which are transferred to hatchlings via the egg yolk and confer a high degree of maternal immunity against homologous challenge and partial immunity to infection with another important species, Eimeria tenella. As an example, in an experiment using(More)
The DNA coding for ribosomal RNA in Physarum polycephalum exists as a collection of extra-chromosomal molecules of molecular weight 37 X 10(6). We have investigated the replication of rDNA, with the following results. (a) Replication of rDNA is unscheduled. This means that molecules that are replicated at any particular time in one mitotic cycle have an(More)
The oocysts of Eimeria tenella, one of the most pathogenic of several species causing chicken coccidiosis, are difficult to distinguish microscopically from several other infective Eimeria species. One copy of a gene coding for 5S ribosomal RNA has been cloned from E. tenella and sequenced. A coding region of 120 nucleotides and an intergenic region of 608(More)
Affinity-purified gametocyte antigens (APGA) from Eimeria maxima, emulsified in Freund's adjuvant, were injected intramuscularly into breeding hens on two or three occasions. As a result, progeny of the immunized hens were partially immune to infection with E. maxima, Eimeria tenella and Eimeria acervulina (with a reduction in total oocyst output of 45-63%(More)