A cryptic plastid and a novel mitochondrial plasmid in gen. and sp. nov. (Ochrophyta) push the frontiers of organellar biology.

Complete plastid loss seems to be very rare among secondarily non-photosynthetic eukaryotes. sp. PRA-24, an amoeboid colourless protist related to the photosynthetic algal class Synchromophyceae (Ochrophyta), is a candidate for such a case based on a previous investigation by transmission electron microscopy.

Redefining Chlorobotryaceae as one of the principal and most diverse lineages of eustigmatophyte algae.

Eustigmatophyceae is one of the ∼17 classes of the vast algal phylum Ochrophyta. Over the last decade, the eustigmatophytes emerged as an expansive group that has grown from the initially recognized handful of species to well over 200 genetically distinct entities (potential species). Yet the majority of eustigs, remain represented by unidentified strains, or even only metabarcode sequences obtained from environmental samples.

A new lineage of non-photosynthetic green algae with extreme organellar genomes.

Background: The plastid genomes of the green algal order Chlamydomonadales tend to expand their non-coding regions, but this phenomenon is poorly understood. Here we shed new light on organellar genome evolution in Chlamydomonadales by studying a previously unknown non-photosynthetic lineage. We established cultures of two new Polytoma-like flagellates, defined their basic characteristics and phylogenetic position, and obtained complete organellar genome sequences and a transcriptome assembly for one of them.

Identification of Nucleolus-Associated Chromatin Domains Reveals a Role for the Nucleolus in 3D Organization of the A. thaliana Genome.

The nucleolus is the site of rRNA gene transcription, rRNA processing, and ribosome biogenesis. However, the nucleolus also plays additional roles in the cell. We isolated nucleoli using fluorescence-activated cell sorting (FACS) and identified nucleolus-associated chromatin domains (NADs) by deep sequencing, comparing wild-type plants and null mutants for the nucleolar protein NUCLEOLIN 1 (NUC1).

A telomerase-independent component of telomere loss in chromatin assembly factor 1 mutants of Arabidopsis thaliana.

Dysfunction of chromatin assembly factor 1 in FASCIATA mutants (fas) of Arabidopsis thaliana results in progressive loss of telomeric DNA. Although replicative telomere shortening is typically associated with incomplete resynthesis of their ends by telomerase, no change in telomerase activity could be detected in vitro in extracts from fas mutants. Besides a possible telomerase malfunction, the telomere shortening in fas mutants could presumably be due to problems with conventional replication of telomeres.