From germline genome to highly fragmented somatic genome:genome-wide DNA rearrangement during the sexual process in ciliated protists

Genomes are incredibly dynamic within diverse eukaryotes and programmed genome rearrangements(PGR)play important roles in generating genomic diversity.However,genomes and chromosomes in metazoans are usually large in size which prevents our understanding of the origin and evolution of PGR.To expand our knowledge of genomic diversity and the evolutionary origin of complex genome rearrangements,we focus on ciliated protists(ciliates).Ciliates are single-celled eukaryotes with highly fragmented somatic chromosomes and massively scrambled germline genomes.PGR in ciliates occurs extensively by removing massive amounts of repetitive and selfish DNA elements found in the silent germline genome dur-ing development of the somatic genome.We report the partial germline genomes of two spirotrich ciliate species,namely Strombidium cf.sulcatum and Halteria grandinella,along with the most compact and highly fragmented somatic genome for S.cf.sulcatum.We provide the first insights into the genome rearrangements of these two species and compare these features with those of other ciliates.Our analyses reveal:(1)DNA sequence loss through evolution and during PGR in S.cf.sulcatum has combined to produce the most compact and efficient nanochromosomes observed to date;(2)the compact,transcriptome-like somatic genome in both species results from extensive removal of a relatively large number of shorter germline-specific DNA sequences;(3)long chromosome breakage site motifs are duplicated and retained in the somatic genome,revealing a complex model of chromosome fragmentation in spirotrichs;(4)gene scrambling and alternative pro-cessing are found throughout the core spirotrichs,offering unique opportunities to increase genetic diversity and regulation in this group.

Dynamic changes of wound-related miRNAs after application of autologous platelet-rich gel in diabetic wounds

To the Editor:Diabetic chronic cutaneous ulcers(DCUs)are among the most common and serious complications of diabetes mellitus.Diabetic foot ulcers are the most common type of DCU and are now considered a global epidemic.[1]The clinical prevention and treatment of DCUs are critical and have remained challenging for clinicians.With the exploration of topical treatment methods,autologous platelet-rich gel(APG)is regarded as an adjuvant therapy to promote wound healing,and it has been widely used for wound repair.[2]Some microRNAs that play a critical role in the whole wound healing process have been found in wound tissues,which we call wound-related miRNAs(wr-miRNAs).However,few studies have explored the dynamic changes of wr-miRNAs during APG treatment.Our study aimed to evaluate the efficacy of APG in treating diabetic wounds and explore the dynamic changes of wr-miRNAs during wound healing.