RESUMEN
All eukaryotes seem to possess proteins that most probably evolved from an ancestral Fe-hydrogenase. These proteins, known as NARF or Nar, do not produce hydrogen. Notably, a small group of rather unrelated unicellular anaerobes and a few algae possess Fe-hydrogenases, which produce hydrogen. In most, but not all organisms, hydrogen production occurs in membrane-bounded organelles, i.e. hydrogenosomes or plastids. Whereas plastids are monophyletic, hydrogenosomes evolved repeatedly and independently from mitochondria or mitochondria-like organelles. A systematic analysis of the various hydrogenosomes and their hydrogenases will contribute to an understanding of the evolution of the eukaryotic cell, and provide clues to the evolutionary origin(s) of the Fe-hydrogenase.
Asunto(s)
Células Eucariotas/enzimología , Hidrogenasas/metabolismo , Proteínas Hierro-Azufre/metabolismo , FilogeniaRESUMEN
The diversity of methanogenic archaea associated with different species of ciliated protozoa in the rumen was analysed. Partial fragments of archaeal SSU rRNA genes were amplified from DNA isolated from single cells from the rumen protozoal species Metadinium medium, Entodinium furca, Ophryoscolex caudatus and Diplodinium dentatum. Sequence analysis of these fragments indicated that although all of the new isolates clustered with sequences previously described for methanogens, there was a difference in the relative distribution of sequences detected here as compared to that of previous work. In addition, many of the novel sequences, although clearly of archaeal origin have relatively low identity to the sequences in database which are most closely related to them.
Asunto(s)
Cilióforos/microbiología , Euryarchaeota/clasificación , ARN de Archaea/análisis , ARN Ribosómico 16S/análisis , Rumen/microbiología , Animales , Cilióforos/parasitología , ADN de Archaea/análisis , ADN Ribosómico/análisis , Euryarchaeota/genética , Filogenia , ARN de Archaea/genética , ARN Ribosómico 16S/genética , OvinosRESUMEN
AIMS: This work was carried out to develop a rapid molecular profiling technique to screen ciliate populations in the rumen of sheep. METHODS AND RESULTS: DGGE was used to study the ciliate diversity in the rumen of sheep. There was considerable variation between sheep which were co-housed, and fed the same diet. However, no difference in the major banding patterns was detected, when samples were collected from a single sheep sampled at different points. Following dietary changes, use of a pair-wise comparison of lanes, demonstrated that although there was still diversity between the ciliate population of sheep, the effects as a result of dietary changes were greater. CONCLUSIONS: The technique generated molecular profiles which are sufficiently different to allow comparison between samples, and to permit molecular ecological studies on the rumen ciliate population. SIGNIFICANCE AND IMPACT OF THE STUDY: The outcome of this study means that ciliate diversity in the rumen may now be studied by those unfamiliar with morphological identification of these organisms.