Analysis of two genomes from the mitochondrion-like organelle of the intestinal parasite Blastocystis: complete sequences, gene content, and genome organization.

Acquisition of mitochondria by the ancestor of all living eukaryotes represented a crucial milestone in the evolution of the eukaryotic cell. Nevertheless, a number of anaerobic unicellular eukaryotes have secondarily discarded certain mitochondrial features, leading to modified organelles such as hydrogenosomes and mitosomes via degenerative evolution. These mitochondrion-derived organelles have lost many of the typical characteristics of aerobic mitochondria, including certain metabolic pathways, morphological traits, and, in most cases, the organellar genome. So far, the evolutionary pathway leading from aerobic mitochondria to anaerobic degenerate organelles has remained unclear due to the lack of examples representing intermediate stages. The human parasitic stramenopile Blastocystis is a rare example of an anaerobic eukaryote with organelles that have retained some mitochondrial characteristics, including a genome, whereas they lack others, such as cytochromes. Here we report the sequence and comparative analysis of the organellar genome from two different Blastocystis isolates as well as a comparison to other genomes from stramenopile mitochondria. Analysis of the characteristics displayed by the unique Blastocystis organelle genome gives us an insight into the initial evolutionary steps that may have led from mitochondria to hydrogenosomes and mitosomes

Comparative analysis of two genomic regions among four strains of Buchnera aphidicola, primary endosymbiont of aphids.

Preliminary analysis of two selected genomic regions of Buchnera aphidicola BCc, the primary endosymbiont of the cedar aphid Cinara cedri, has revealed a number of interesting features when compared with the corresponding homologous regions of the three B. aphidicola genomes previously sequenced, that are associated with different aphid species. Both regions exhibit a significant reduction in length and gene number in B. aphidicola BCc, as it could be expected since it possess the smallest bacterial genome. However, the observed genome reduction is not even in both regions, as it appears to be dependent on the nature of their gene content. The region fpr-trxA, that contains mainly metabolic genes, has lost almost half of its genes (45.6%) and has reduced 52.9% its length. The reductive process in the region rrl-aroK, that contains mainly ribosomal protein genes, is less dramatic, since it has lost 9.3% of genes and has reduced 15.5% of its length. Length reduction is mainly due to the loss of protein-coding genes, not to the shortening of ORFs or intergenic regions. In both regions, G+C content is about 4% lower in BCc than in the other B. aphidicola strains. However, when only conserved genes and intergenic regions of the four B. aphidicola strains are compared, the G+C reduction is higher in the fpr-trxA region

Intracerebral haemorrhage in a dog with steroid-responsive meningitis arteritis

A one-year and six-month-old female neutered Boxer dog was presented with a four-day history of pyrexia, lethargy and neck pain. An intracerebral haemorrhage and a mediastinal mass were identified. Cerebrospinal fluid analysis revealed severe neutrophilic pleocytosis, and steroid-responsive meningitis arteritis (SRMA) was suspected. A significant improvement was observed with immunosuppressive steroid therapy and subsequent imaging revealed a reduction in size of the intracerebral haemorrhage and disappearance of the mediastinal mass. SRMA is a systemic disease with potential involvement of multiple organs. Intracerebral haemorrhage can occur secondary to SRMA and can have a successful outcome

Intra-parenchymal brainstem haemorrhage secondary to iatrogenic needle injury after a parenteral injection in a cat

Case summary A 6-month-old female domestic shorthair cat was presented with acute onset non-ambulatory right hemiparesis and horizontal nystagmus following an injection attempt in the neck, during which the cat did not cooperate. Magnetic resonance imaging (MRI) revealed a well-defined intra-axial lesion on the right side of the myelencephalon. The lesion was T2-weighted hypointense and T1-weighted hypointense to isointense to grey matter, non-contrast enhancing, with perilesional oedema and signal void on T2*-weighted images. A linear hyperintense lesion in the muscles of the right dorsolateral aspect of the neck on short tau inversion recovery images was also observed. These MRI findings were consistent with iatrogenic brainstem haemorrhage and a muscle needle tract. The cat made a good recovery with just mild residual neurological deficits 6 weeks after the injury. Relevance and novel information To our knowledge, this is the first report of an iatrogenic brainstem needle injury in a cat and the first report of a central nervous system iatrogenic trauma after a parenteral injection. Care should be taken with neck parenteral injections, especially in the cranial cervical area