Although heredity mostly relies on the transmission of DNA sequence, additional molecular and cellular features are heritable across several generations. In the nematode Caenorhabditis elegans, insights into such unconventional inheritance result from two lines of work. First, the mortal germline (Mrt) phenotype was defined as a multigenerational phenotype whereby a selfing lineage becomes sterile after several generations, implying multigenerational memory [1, 2]. Second, certain RNAi effects are heritable over several generations in the absence of the initial trigger [3-5]. Both lines of work converged when the subset of Mrt mutants that are heat sensitive were found to closely correspond to mutants defective in the RNAi-inheritance machinery, including histone modifiers [6-9]. Here, we report the surprising finding that several C. elegans wild isolates display a heat-sensitive mortal germline phenotype in laboratory conditions: upon chronic exposure to higher temperatures, such as 25°C, lines reproducibly become sterile after several generations. This phenomenon is reversible, as it can be suppressed by temperature alternations at each generation, suggesting a non-genetic basis for the sterility. We tested whether natural variation in the temperature-induced Mrt phenotype was of genetic nature by building recombinant inbred lines between the isolates MY10 (Mrt) and JU1395 (non-Mrt). Using bulk segregant analysis, we detected two quantitative trait loci. After further recombinant mapping and genome editing, we identified the major causal locus as a polymorphism in the set-24 gene, encoding a SET- and SPK-domain protein. We conclude that C. elegans natural populations may harbor natural genetic variation in epigenetic inheritance phenomena.

The study of science-making is a growing discipline that builds largely on online publication and citation databases, while prepublication processes remain hidden. Here, we report on results from a large-scale survey of the submission process, covering 923 scientific journals from the biological sciences in years 2006 to 2008. Manuscript flows among journals revealed a modular submission network, with high-impact journals preferentially attracting submissions. However, about 75% of published articles were submitted first to the journal that would publish them, and high-impact journals published proportionally more articles that had been resubmitted from another journal. Submission history affected post-publication impact: Resubmissions from other journals received significantly more citations than first-intent submissions, and resubmissions between different journal communities received significantly fewer citations.

Ribosome biogenesis is a major conserved cellular pathway that requires both ribosomal proteins and many preribosomal factors. Most of the pre-60S factors are recycled into the nucleus; some of them shuttle between the nucleus and the cytoplasm while a few others, like Rei1, are strictly cytoplasmic and are mostly involved in the dissociation/recycling of the pre-60S shuttling factors. Here, we investigated the role of the Jjj1 Hsp40 chaperone in ribosome biogenesis. The absence of Jjj1 leads to a cold sensitive phenotype, a defect in the relative amount of the large ribosomal subunit with the appearance of halfmers, and to cytoplasmic accumulation of shuttling factors such as Arx1 and Alb1, which stay bound to the pre-60S particles. Jjj1 is, thus, a novel pre-60S factor involved in the last cytoplasmic steps of the large ribosomal subunit biogenesis. We report the biochemical association of Jjj1 and Rei1 to similar pre-60S complexes, their two-hybrid interactions, and their functional links. Altogether, these results indicate that Rei1 and Jjj1 share many common features. However, while the functions of Jjj1 and Rei1 partially overlap, we could distinguish specific role of the two proteins in Arx1/Alb1 and Tif6 recycling. We propose that Jjj1 is preferentially required for the release of Arx1 and Alb1 shuttling factors from the cytoplasmic pre-60S particles while Rei1 is preferentially involved in their recycling.