In cycling cells, the rDNAs are expressed from telophase to the end of G2 phase. The early resumption of rDNA transcription at telophase raises the question of the fate of the rDNA transcription machinery during mitosis. At the beginning of mitosis, rDNA transcription is arrested, and the rDNAs are clustered in specific chromosomal sites, the nucleolar organizer regions (NOR). In human cells, w...

The protozoan parasite Toxoplasma gondii causes severe opportunistic infections. Here, we report an unexpected diagnosis of cerebral toxoplasmosis. T. gondii was diagnosed by 16S and D2 large-subunit (LSU) ribosomal DNA (rDNA) sequencing of a cerebral biopsy specimen and confirmed by T. gondii-specific PCR and immunohistochemistry. The patient was later diagnosed with HIV/AIDS.

Gregarines are thought to be deep-branching apicomplexans. Accordingly, a robust inference of gregarine phylogeny is crucial to any interpretation of apicomplexan evolution, but molecular sequences from gregarines are restricted to a small number of small-subunit (SSU) rDNA sequences from derived taxa. This work examines the usefulness of SSU rDNA and b-tubulin sequences for inferring gregarine...

Gregarines are thought to be deep-branching apicomplexans. Accordingly, a robust inference of gregarine phylogeny is crucial to any interpretation of apicomplexan evolution, but molecular sequences from gregarines are restricted to a small number of small-subunit (SSU) rDNA sequences from derived taxa. This work examines the usefulness of SSU rDNA and beta-tubulin sequences for inferring gregar...

Giardia lamblia telomeres have been isolated from a library enriched for repaired chromosome ends by (i) screening with a Plasmodium falciparum telomere and (ii) differential hybridization with Bal 31-digested and total G. lamblia DNA. Analysis of three clones isolated by this strategy has identified multiple tandem repeats of the 5-mer TAGGG. An oligonucleotide containing these repeats recogni...

Panaeolus punjabensis M. Asif, Q. Firdous, A. Izhar, Niazi & Khalid sp. nov. was collected from three different localities (Bahawalnagar, Kasur, and Lahore) in Punjab, Pakistan. Morphological observations phylogenetic analyses based on nuclear encoded internal transcribed spacers (ITS1-5.8S-ITS2 = ITS) D1/D2 domain of large subunit (28S) rDNA confirmed the taxonomic distinctness this specie...

Complete nucleotide sequences have been determined for atp6 from Suillus luteus and cox3 from Suillus sinuspaulianus (Boletales, Hymenomycetes, Basidiomycota), which code for ATPase subunit 6 and cytochrome oxidase subunit 3, respectively. These sequences were used to design PCR primers for the amplification of partial atp6 and cox3 sequences from other members of the Boletales and outgroup tax...

The Tremellomycetes (Basidiomycota) contains a large number of unicellular and dimorphic fungi with stable free-living unicellular states in their life cycles. These fungi have been conventionally classified as basidiomycetous yeasts based on physiological and biochemical characteristics. Many currently recognised genera of these yeasts are mainly defined based on phenotypical characters and ar...

Phylogenetic and genetic relationships among 10 North American Armillaria species were analysed using sequence data from ribosomal DNA (rDNA), including intergenic spacer (IGS-1), internal transcribed spacers with associated 5.8S (ITS + 5.8S), and nuclear large subunit rDNA (nLSU), and amplified fragment length polymorphism (AFLP) markers. Based on rDNA sequence data, the nLSU region is less va...

The Tetrahymena thermophila origin recognition complex (ORC) contains an integral RNA subunit, 26T RNA, which confers specificity to the amplified ribosomal DNA (rDNA) origin by base pairing with an essential cis-acting replication determinant--the type I element. Using a plasmid maintenance assay, we identified a 6.7 kb non-rDNA fragment containing two closely associated replicators, ARS1-A (0...