Search

It has been long thought that RNA Polymerase (Pol) II transcriptional regulation does not operate in trypanosomes. However, recent reports have suggested that these organisms could regulate RNA Pol II transcription by epigenetic mechanisms. In this paper, we investigated the role of TbRRM1 in transcriptional regulation of RNA Pol II‐dependent genes by focusing both in genes located in a particular polycistronic transcription unit (PTU) and in the monocistronic units of the SL‐RNA genes. We showed that TbRRM1 is recruited throughout the PTU, with a higher presence on genes than intergenic regions. However, its depletion leads both to the decrease of nascent RNA and to chromatin compaction only of regions located distal to the main transcription start site. These findings suggest that TbRRM1 facilitates the RNA Pol II transcriptional elongation step by collaborating to maintain an open chromatin state in particular regions of the genome. Interestingly, the SL‐RNA genes do not recruit TbRRM1 and, after TbRRM1 knockdown, nascent SL‐RNAs accumulate while the chromatin state of these regions remains unchanged. Although it was previously suggested that TbRRM1 could regulate RNA Pol II‐driven genes, we provide here the first experimental evidence which involves TbRRM1 to transcriptional regulation. [ABSTRACT FROM AUTHOR]

Based on both morphological and molecular information, two new euplotid genera Apodiophrys n. g. and Heterodiophrys n. g. are described in the present paper. Apodiophrys n. g. is defined as sculptured Diophryinae with bipartite adoral zone; frontoventral cirri arranged in Diophrys-pattern; marginal cirri located in two clearly separated groups. Heterodiophrys n. g. is recognizable by the combination of Diophrys-like frontoventral cirri and the unique structure of several marginal cirri that are arranged in a long row. The type species for both new genera, Apodiophrys ovalis n. sp. and Heterodiophrys zhui n. sp., collected from southern China sea, are described. The small subunit rRNA (SSU rRNA) gene sequences for both new taxa are determined. Phylogenetic analyses based on these data indicate that Apodiophrys is most closely related to Paradiophrys, which then clusters with Uronychia species. Thus, Apodiophrys–Paradiophrys is separated from other typical Diophrys-like genera in the SSU rRNA gene trees. The new genus Heterodiophrys is basal to the sister group of Diophrys–Diophryopsis, hence belongs to the “core” Diophrys-complex. [ABSTRACT FROM AUTHOR]

The survival of an isolate of Hyphochytrium catenoides collected from soil in the Blue Mountains in eastern New South Wales, Australia, was tested under extreme conditions in the laboratory. This isolate recovered growth after being subjected to drying on filter paper, to heat while desiccated, to hypersalinity, to strict anaerobic conditions, to freezing temperatures, and to a short period in solutions at pH 2.8–11.2. The capacity to survive under these conditions in the laboratory suggests adaptation to fluctuating conditions in the soil. The partial DNA sequence of the 28S ribosomal RNA gene in the isolate from New South Wales was 98% similar to that in an isolate from Arizona with a similar morphology. [ABSTRACT FROM AUTHOR]