Obligatory parthenogenesis and TE load: Bacillus stick insects and the R2 non‐LTR retrotransposon

Abstract

Transposable elements (TEs) are selfish genetic elements whose self-replication is contrasted by the host genome. In this context, host reproductive strategies are predicted to impact on both TEs load and activity. The presence and insertion distribution of the non-LTR retrotransposon R2 was here studied in populations of the strictly bisexual Bacillus grandii maretimi and of the obligatory parthenogenetic Bacillus atticus atticus. Furthermore, data were also obtained from the offspring of selected B. a. atticus females. At the population level, the gonochoric B. g. maretimi showed a significantly higher R2 load than the obligatory parthenogenetic B. a. atticus. The comparison with bisexual and unisexual Bacillus rossius populations showed that their values were higher than those recorded for B. a. atticus and similar, or even higher, than those of B. g. maretimi. Consistently, an R2 load reduction is scored in B. a. atticus offspring even if with a great variance. On the whole, data here produced indicate that in the obligatory unisexual B. a. atticus R2 is active and that mechanisms of molecular turnover are effective. Furthermore, progeny analyses show that, at variance of the facultative parthenogenetic B. rossius, the R2 activity is held at a lower rate. Modeling parental-offspring inheritance, suggests that in B. a. atticus recombination plays a major role in eliminating insertions rather than selection, as previously suggested for unisexual B. rossius progeny, even if in both cases a high variance is observed. In addition to this, mechanisms of R2 silencing or chances of clonal selection cannot be ruled out.

Draft genomes and genomic divergence of two Lepidurus tadpole shrimp species (Crustacea, Branchiopoda, Notostraca)

“…The present analysis, carried out with the same method described in Bast et al (, i.e., read mapping as a proxy for TE content), indicated that the TE content of the putatively parthenogenetic L. apus lubbocki is significantly lower than that of L. arcticus . These preliminary results, therefore, are in line with the hypothesis that TE lineages with lower proliferating activity were selected in parthenogenetic organisms to favour the survival of both host organisms and TE lineages (Bonandin et al, ; Bull, Molineux, & Rice, ; Wright & Finnegan, ). However, it could be interesting to evaluate TE content variation at the population level, considering polymorphic insertions and the relative frequency of these insertions within populations/taxa.…”

“…However, empirical studies on bisexual and parthenogenetic lineages have given contrasting results. Studies on Bacillus stick insects have indicated that some parthenogenetic lineages have a relatively high TE load (Bonandin, Scavariello, Luchetti, & Mantovani, ; Bonandin, Scavariello, Mingazzini, Luchetti, & Mantovani, ), while analyses have shown less insertions in obligately parthenogenetic Daphnia lineages than in cyclically parthenogenetic Daphnia lineages (Valizadeh & Crease, ). Recent genomewide studies have highlighted similar TE contents in bisexual and parthenogenetic taxa, including D. pulex lineages (Bast et al, ; Kraaijeveld et al, ).…”

High Prevalence and Disease Correlation of Autoantibodies Against p40 Encoded by Long Interspersed Nuclear Elements in Systemic Lupus Erythematosus

“…Indeed, transfection of LINE‐1 into cells induces production of IFNβ . Also, a recent study showed that blood mononuclear cells from ~17% of SLE patients have detectable cyclic GMP‐AMP, the second messenger exclusively made by cGAS when it is activated by aberrant intracellular DNA . Given the minute quantities and rapid turnover of this second messenger, these data likely represent an underestimate.…”

Parental species and hybrid descendants of Bacillus (Insecta Phasmatodea) show different patterns of highly amplified, colocalized ribosomal and telomeric sequences

“…We suggest a link between the variability for number and location of colocalized NOR/telomeric sequences and the presence of R2 retrotransposons. R2 retrotransposons, presenting a strict sequence specificity for an insertion target-site in the 28S rDNA, have been reported in bisexual and parthenogenetic populations of B. rossius, with a very high copy-number (Martoni et al 2015;Satovic et al 2016;Bonandin et al 2017;. Moreover, increased chromosome breakages and rearrangements have been observed in all taxa embodying the B. rossius genome, particularly in the parthenogenetic hybrids ( Figure 5(b,c,d)).…”