Using both traditional methods and broad-range 18S ribosomal DNA (rDNA) polymerase chain reaction, we examined 2 cases of lethal cestodiasis, in which the disease agent had been poorly identified or misidentified. In one case, involving a patient with AIDS, we identified the human dwarf tapeworm, Hymenolepis nana, as a cause of aberrant metastatic larval disease. In the second case with similar...

This study examined the sterol compositions of 102 dinoflagellates using clustering and cluster validation techniques, as a means of determining the relatedness of the organisms. In addition, dinoflagellate sterol-based relationships were compared statistically to 18S rDNA-based phylogenetic relationships using the Mantel test. Our results indicated that the examined dinoflagellates formed six ...

Ribosomal RNA genes are abundant repetitive sequences in most eukaryotes. Ribosomal DNA (rDNA) contains many insertions derived from mobile elements including non-long terminal repeat (non-LTR) retrotransposons. R2 is the well-characterized 28S rDNA-specific non-LTR retrotransposon family that is distributed over at least 4 bilaterian phyla. R2 is a large family sharing the same insertion speci...

Recent molecular phylogenetic analyses of 18S rDNA have indicated that parasitic lice (order Phthiraptera) are possibly polyphyletic. These analyses recovered one of the parasitic louse suborders, Amblycera, as the sister group to the free-living booklouse family Liposcelididae. We further tested this hypothesis using DNA sequences from five genes: nuclear 18S rDNA, Histone 3, and wingless and ...

The Buffelgrass (Cenchrus ciliaris L., Poaceae) is one of the most important pasturage grasses due to its high productivity and good forage qualities. This species possess a high adaptability to bioclimatic constraints of arid zones and may be used for the restoration of degraded arid ecosystems. Tunisian populations present three ploidy levels (4x, 5x and 6x) with a basic chromosome number x=9...

Pre-rRNA transcription by RNA Polymerase I (Pol I) is very robust on active rDNA repeats. Loss of yeast Topoisomerase I (Top1) generated truncated pre-rRNA fragments, which were stabilized in strains lacking TRAMP (Trf4/Trf5-Air1/Air2-Mtr4 polyadenylation complexes) or exosome degradation activities. Loss of both Top1 and Top2 blocked pre-rRNA synthesis, with pre-rRNAs truncated predominately i...

The evolutionary history and times of divergence of triatomine bug lineages are estimated from molecular clocks inferred from nucleotide sequences of the small subunit SSU (18S) and the second internal transcribed spacer (ITS-2) of the nuclear ribosomal DNA of these reduviids. The 18S rDNA molecular clock rate in Triatominae, and Prosorrhynchan Hemiptera in general, appears to be of 1.8% per 10...

Wrasses (Labridae) are extremely diversified marine fishes, whose species exhibit complex interactions with the reef environment. They are widely distributed in the Indian, Pacific and Atlantic oceans. Their species have displayed a number of karyotypic divergent processes, including chromosomal regions with complex structural organization. Current cytogenetic information for this family is phy...

The two main rDNA size classes in the genome of Ascaris lumbricoides consist of 8.8 kb and 8.4 kb long repeating units present in a quantitative ratio of roughly 10:1. They both contain the genes coding for 18 , 5.8S and 26S ribosomal RNAs. The length heterogeneity is due to a 450 bp long spacer region localized in the longer repeating unit which begins 870 bp upstream of the 5'-end 18S gene. A...

Demodex mites are a group of hair follicle and sebaceous gland-dwelling species. The species of these mites found on humans are arguably the animals with which we have the most intimate interactions. Yet, their prevalence and diversity have been poorly explored. Here we use a new molecular method to assess the occurrence of Demodex mites on humans. In addition, we use the 18S rRNA gene (18S rDN...