J.M. Ubeda

Trichuris suis and Trichuris trichiura are different nematode species

In this paper, a morphological and biometrical study by optical microscopy and scanning electronic microscopy (SEM) of Trichuris suis isolated from different hosts (Sus scrofa domestica and Sus scrofa scrofa) and Trichuris trichiura isolated from chimpanzee, has been carried out. Our results demonstrate the existence of typical pericloacal papillae in both species. Biometrical parameters of T. suis and T. trichiura overlapped but males and females of T. trichiura tended to be shorter and thinner than those of T. suis. Our results suggest that T. suis and T. trichiura cannot be differentiated using standard procedures as morphological and biometrical determinations. Thus, the ITS1-5.8S-ITS2 region of the ribosomal DNA was sequenced to allow a differentiation between T. suis and T. trichiura on genetic level. The ITS1 and ITS2 sequences derived from T. trichiura eggs isolated from feces of primates (Colobus guereza kikuyensis and Nomascus gabriellae) showed clear differences to the respective sequences of T. suis derived from eggs of different porcine hosts. The 5.8S gene was similar between the two species. Sequences obtained from different populations of the same species showed no significant differences indicating that the ITS1-5.8S-ITS2 sequences reported in this study are representative for T. trichiura and T. suis, respectively. Phylogenetic relationships have been determined attending to the ITS1 and ITS2 sequences from different species of the genus Trichuris. In conclusion, T. trichiura and T. suis are considered to be closely related but genetically different species. Both species can be easily and reliably distinguished by a PCR-RFLP analysis of the ITS1 and ITS2 sequences with different restriction enzymes.

Phylogenetic Relationships in Rhinonyssid Mites (Acari: Rhinonyssidae) Based on Mitochondrial 16S rDNA Sequences

A 390 bp region of the 16S rDNA gene was sequenced from six species ofrhinonyssid mites (Tinaminyssus columbae, T. minisetosum, Sternostomaturdi, S. sternahirundo, S. fulicae and Ptilonyssus euroturdi) andtwo subspecies (Tinaminyssus melloi melloi andTinaminyssus melloi streptopeliae) to examine the level ofsequence variation and the taxonomic levels to show utility in phylogenyestimation. Furthemore, two different geographic locations of T. m.melloi and T. m. streptopeliae were analyzed todetect variation between populations. Molecular data revealed the existence oftwo distinct groups in the genus Tinaminyssus parasitic oncolumbiform birds. These results are in agreement with those reported by someauthors using morphological characters. Sternostoma turdi parasitizing aerial birds appeared to be phylogenetically separated from otherspecies of this genus isolated from aquatic birds. Moreover, our studyaddressesthe validity of the subspecies status of T. melloistreptopeliae. This region of the mitochondrial 16S rDNA gene is auseful marker for inferring phylogenetic relationships among closely relatedrhinonyssid species, but not for more distantly related taxa.

Utility of ITS1-5.8S-ITS2 and 16S mitochondrial DNA sequences for species identification and phylogenetic inference within the Rhinonyssus coniventris species complex (Acari: Rhinonyssidae)

The complete internal transcribed spacer 1 (ITS1), 5.8S rDNA, and ITS2 region of the ribosomal DNA and a 390-bp region of the 16S rDNA gene from five taxa belonging to Rhinonyssus (Rhinonyssus vanellus, Rhinonyssus tringae, Rhinonyssus neglectus, Rhinonyssus echinipes from Kentish plover, and Rhinonyssus echinipes from grey plover) were sequenced to examine the level of sequence variation and the taxonomic levels to show utility in phylogeny estimation. Our data show that these molecular markers can help to discriminate between species and populations included in the Rhinonyssus coniventris complex (R. tringae, R. neglectus, R. echinipes), which are morphologically very close and difficult to separate by classic methods. A comparative study with sequences from other rhinonyssid mites previously published was also carried out. The resulting phylogenetic tree inferred from ITS1–5.8S–ITS2 region sequences obtained in this paper, together with those from other 11 taxa of rhinonyssid, shows slight differences from the current taxonomy of the Rhinonyssidae. This study appeals for the revision of the taxonomic status of the R. coniventris complex, as well as for the species included within it.

Cytochrome oxidase subunit 1 and mitochondrial 16S rDNA sequences of Trichuris skrjabini (Tricocephalida: Trichuridae)

The partial mitochondrial cytochrome c-oxidase subunit 1 gene (cox 1) and partial mitochondrial 16S ribosomal DNA of Trichuris skrjabini (Baskakov 1924) isolated from Capra hircus have been amplified and sequenced. The analyses of multiple sequence alignments of mitochondrial 16S rDNA and cox 1 of T. skrjabini revealed high homology with those of Trichinella species. For the first time, the mitochondrial DNA gene sequences of one species of trichurid nematode have been cited.

Free-living amoebae in sediments from the Lascaux Cave in France

The research was initially supported by the Ministry of Culture and Communication, France, project “Ecologie microbienne de la grotte de Lascaux”. Later, the work was supported by the Spanish Ministry of Science and Innovation, project TCP CSD2007- 00058.