Transcriptome Analysis on Chlorpyrifos Detoxification in \u3cem\u3eUronema marinum\u3c/em\u3e (Ciliophora, Oligohymenophorea)

Chlorpyrifos (CPF) pollution has drawn widespread concerns in aquatic environments due to its risks to ecologic system, however, the response mechanisms of ciliates to CPF pollution were poorly studied. In our current work, the degradation of CPF by ciliates and the morphological changes of ciliates after CPF exposure were investigated. In addition, the transcriptomic profiles of the ciliate Uronema marinum, with and without exposure with CPF, were detected using digital gene expression technologies. De novo transcriptome assembly 166,829,634 reads produced from three groups (untreated, CPF treatment at 12 h and 24 h) by whole transcriptome sequencing (RNA-Seq). Gene ontology (GO) and Kyoto Encyclopaedia of Genes and Genomes (KEGG) pathways were analyzed in all unigenes and different expression genes to identify their biological functions and processes. Furthermore, the results indicated that genes related to the stress response, cytoskeleton and cell structure proteins, and antioxidant systems might play an important role in the resistance mechanism of ciliates. The enzyme activities of SOD and GST after CPF stress were also analyzed, and the result showed the good antioxidant capacity of SOD and GST in ciliates inferred from the increase of the activities of the two enzymes. The ciliate Uronema marinum showed a resistance response to chlorpyrifos stress at the transcriptomic level in the present work, which indicates that ciliates can be considered as a potential bioremediation agent

Prevalent Introgression Underlies Convergent Evolution in the Diversification of Pungitius Sticklebacks

New mutations and standing genetic variations contribute significantly to repeated phenotypic evolution in sticklebacks. However, less is known about the role of introgression in this process. We analyzed taxonomically and geographically comprehensive genomic data from Pungitius sticklebacks to decipher the extent of introgression and its consequences for the diversification of this genus. Our results demonstrate that introgression is more prevalent than suggested by earlier studies. Although gene flow was generally bidirectional, it was often asymmetric and left unequal genomic signatures in hybridizing species, which might, at least partly, be due to biased hybridization and/or population size differences. In several cases, introgression of variants from one species to another was accompanied by transitions of pelvic and/or lateral plate structures-important diagnostic traits in Pungitius systematics-and frequently left signatures of adaptation in the core gene regulatory networks of armor trait development. This finding suggests that introgression has been an important source of genetic variation and enabled phenotypic convergence among Pungitius sticklebacks. The results highlight the importance of introgression of genetic variation as a source of adaptive variation underlying key ecological and taxonomic traits. Taken together, our study indicates that introgression-driven convergence likely explains the long-standing challenges in resolving the taxonomy and systematics of this small but phenotypically highly diverse group of fish.Peer reviewe