High Nucleotide Substitution Rates Associated with Retrotransposon Proliferation Drive Dynamic Secretome Evolution in Smut Pathogens.

Transposable elements (TEs) play a pivotal role in shaping diversity in eukaryotic genomes. The covered smut pathogen on barley, Ustilago hordei, encountered a recent genome expansion. Using long reads, we assembled genomes of 6 U. hordei strains and 3 sister species, to study this genome expansion. We found that larger genome sizes can mainly be attributed to a higher genome fraction of long terminal repeat retrotransposons (LTR-RTs). In the studied smut genomes, LTR-RTs fractions are the largest in U. hordei and are positively correlated with the mating-type locus sizes, which is up to ~560 kb in U. hordei. Furthermore, LTR-RTs were found to be associated with higher nucleotide substitution levels, as these occur in specific genome regions of smut species with a recent LTR-RT proliferation. Moreover, genes in genome regions with higher nucleotide substitution levels generally reside closer to LTR-RTs than other genome regions. Genome regions with many nucleotide substitutions encountered an especially high fraction of CG substitutions, which is not observed for LTR-RT sequences. The high nucleotide substitution levels particularly accelerate the evolution of secretome genes, as their more accessory nature results in substitutions that often lead to amino acid alterations. IMPORTANCE Genomic alteration can be generated through various means, in which transposable elements (TEs) can play a pivotal role. Their mobility causes mutagenesis in itself and can disrupt the function of the sequences they insert into. They also impact genome evolution as their repetitive nature facilitates nonhomologous recombination. Furthermore, TEs have been linked to specific epigenetic genome organizations. We report a recent TE proliferation in the genome of the barley covered smut fungus, Ustilago hordei. This proliferation is associated with a distinct nucleotide substitution regime that has a higher rate and a higher fraction of CG substitutions. This different regime shapes the evolution of genes in subjected genome regions. We hypothesize that TEs may influence the error-rate of DNA polymerase in a hitherto unknown fashion.

Effect of sex difference on platelet aggregation using an optical method in healthy subjects.

There are many studies reporting conflicting results of sex differences on various platelet functions. The purpose of this study was to investigate whether sex differences could affect platelet aggregation results using an optical method in healthy subjects. A total of 42 subjects, 21 males and 21 females, were included in the study. Platelet aggregation was induced by adenosine diphosphate (ADP; 5 microm), collagen (2 microg/ml), and epinephrine (10 microm). Optical aggregation was performed using a turbidometric method. In all platelet aggregation tests ADP, collagen and epinephrine were studied; there was no significant difference between females and males in platelet aggregation amplitudes and slopes. As a result, sex difference does not affect platelet aggregation performed with this optical method in healthy subjects. This result supports that there is no need for sex differentiation while composing control groups in platelet aggregation studies using the optical method.