The moth Spodoptera frugiperda is a well-known pest of crops throughout the Americas, which consists of two strains adapted to different host-plants: the first feeds preferentially on corn, cotton and sorghum whereas the second is more associated with rice and several pasture grasses. Though morphologically indistinguishable, they exhibit differences in their mating behavior, pheromone compositions, and show development variability according to the host-plant. Though the latter suggest that both strains are different species, this issue is still highly controversial because hybrids naturally occur in the wild, not to mention the discrepancies among published results concerning mating success between the two strains. In order to clarify the status of the two host-plant strains of S. frugiperda, we analyze features that possibly reflect the level of post-zygotic isolation: (1) first generation (F1) hybrid lethality and sterility; (2) patterns of meiotic segregation of hybrids in reciprocal second generation (F2), as compared to the meiosis of the two parental strains. We found a significant reduction of mating success in F1 in one direction of the cross and a high level of microsatellite markers showing transmission ratio distortion in the F2 progeny. Our results support the existence of post-zygotic reproductive isolation between the two laboratory strains and are in accordance with the marked level of genetic differentiation that was recovered between individuals of the two strains collected from the field. Altogether these results provide additional evidence in favor of a sibling species status for the two strains.Electronic supplementary materialThe online version of this article (doi:10.1007/s10709-015-9829-2) contains supplementary material, which is available to authorized users.

No abstract

B cells ensure humoral immune responses due to the production of Ag-specific memory B cells and Ab-secreting plasma cells. In secondary lymphoid organs, Ag-driven B cell activation induces terminal maturation and Ig isotype class switch (class switch recombination [CSR]). CSR creates a virtually unique locus in every B cell clone by intrachromosomal recombination between two switch (S) regions upstream of each C region gene. Amount and structural features of CSR junctions reveal valuable information about the CSR mechanism, and analysis of CSR junctions is useful in basic and clinical research studies of B cell functions. To provide an automated tool able to analyze large data sets of CSR junction sequences produced by high-throughput sequencing (HTS), we designed CSReport, a software program dedicated to support analysis of CSR recombination junctions sequenced with a HTS-based protocol (Ion Torrent technology). CSReport was assessed using simulated data sets of CSR junctions and then used for analysis of Sμ-Sα and Sμ-Sγ1 junctions from CH12F3 cells and primary murine B cells, respectively. CSReport identifies junction segment breakpoints on reference sequences and junction structure (blunt-ended junctions or junctions with insertions or microhomology). Besides the ability to analyze unprecedentedly large libraries of junction sequences, CSReport will provide a unified framework for CSR junction studies. Our results show that CSReport is an accurate tool for analysis of sequences from our HTS-based protocol for CSR junctions, thereby facilitating and accelerating their study.

The viral load of the ubiquitous and nonpathogenic torque teno virus (TTV) is associated with the grade of immunosuppression of its host. The development of next‐generation sequencing (NGS) allowed to describe the human virome of the blood compartment in transplanted patients, and showed that TTV is the most important part of the virome. This study is a descriptive retrospective pilot study of sequencing plasma samples from 15 matched donors and recipients. After sample processing, nucleic acids were amplified by rolling circle amplification and submitted to NGS by ion proton sequencing technology. Results were analyzed after mapping of reads on the 29 TTV reference genomes and de novo assembling of the reads with MIRA software. The number of TTV species present in donors and recipients was, on average, 12 in donors and 33 in recipients. TTV species predominantly present in donors were TTV‐13 and TTV‐18; and in recipients were TTV‐P15‐2, TTV‐27, TTV‐HD14a, and TTV‐22. We highlighted a significant variability in abundance and composition in sequential samples from recipients. Temporal evolution of TTV populations was clearly observed in recipients, but no preferential transmission of a species from donor to recipient was evidenced. Diversity and population expansion were observed in kidney recipients. Further study of TTV species could help assess the potential impact of each species of this virus.