The ability to inherit learned information from parents could be evolutionarily beneficial, enabling progeny to better survive dangerous conditions. We discovered that, after C. elegans have learned to avoid the pathogenic bacteria Pseudomonas aeruginosa (PA14), they pass this learned behavior on to their progeny, through either the male or female germline, persisting through the fourth generation. Expression of the TGF-b ligand DAF-7 in the ASI sensory neurons correlates with and is required for this transgenerational avoidance behavior. Additionally, the Piwi Argonaute homolog PRG-1 and its downstream molecular components are required for transgenerational inheritance of both avoidance behavior and ASI daf-7 expression. Animals whose parents have learned to avoid PA14 display a PA14 avoidancebased survival advantage that is also prg-1 dependent, suggesting an adaptive response. Transgenerational epigenetic inheritance of pathogenic learning may optimize progeny decisions to increase survival in fluctuating environmental conditions.

C. elegans is exposed to many different bacteria in its environment, and must distinguish pathogenic from nutritious bacterial food sources. Here, we show that a single exposure to purified small RNAs isolated from pathogenic Pseudomonas aeruginosa (PA14) is sufficient to induce pathogen avoidance, both in the treated animals and in four subsequent generations of progeny. The RNA interference and piRNA pathways, the germline, and the ASI neuron are required for bacterial small RNA-induced avoidance behavior and transgenerational inheritance. A single non-coding RNA, P11, is both necessary and sufficient to convey learned avoidance of PA14, and its C. elegans target, maco-1, is required for avoidance. A natural microbiome Pseudomonas isolate, GRb0427, can induce avoidance via its small RNAs, and the wild C. elegans strain JU1580 responds similarly to bacterial sRNA. Our results suggest that this ncRNA-dependent mechanism evolved to survey the worm's microbial environment, use this information to make appropriate behavioral decisions, and pass this information on to its progeny.Small RNAs from P. aeruginosa induce species-specific avoidance C. elegans is surrounded by and consumes bacteria as its primary nutrient source. Its natural habitat contains many different bacterial species; about a third of these are in the Pseudomonas family (Samuel et al., 2016), which can be either beneficial or detrimental to the worms. Despite their natural attraction to pathogenic Pseudomonas aeruginosa (PA14), C. elegans can learn to avoid this pathogen after becoming ill (Zhang et al., 2005). Recently, we discovered that worms epigenetically pass on to their progeny this learned avoidance of PA14

The human pathogen Staphylococcus aureus acquires heme iron from hemoglobin (Hb) via the action of a series of iron-regulated surface determinant (Isd) proteins. The cell wall anchored IsdB protein is recognized as the predominant Hb receptor, and is comprised of two NEAr transporter (NEAT) domains that act in concert to bind, extract, and transfer heme from Hb to downstream Isd proteins. Structural details of the NEAT 2 domain of IsdB have been investigated, but the molecular coordination between NEAT 2 and NEAT 1 to extract heme from hemoglobin has yet to be characterized. To obtain a more complete understanding of IsdB structure and function, we have solved the 3D solution structure of the NEAT 1 domain of IsdB (IsdBN1) spanning residues 125–272 of the full-length protein by NMR. The structure reveals a canonical NEAT domain fold and has particular structural similarity to the NEAT 1 and NEAT 2 domains of IsdH, which also interact with Hb. IsdBN1 is also comprised of a short N-terminal helix, which has not been previously observed in other NEAT domain structures. Interestingly, the Hb binding region (loop 2 of IsdBN1) is disordered in solution. Analysis of Hb binding demonstrates that IsdBN1 can bind metHb weakly and the affinity of this interaction is further increased by the presence of IsdB linker domain. IsdBN1 loop 2 variants reveal that phenylalanine 164 (F164) of IsdB is necessary for Hb binding and rapid heme transfer from metHb to IsdB. Together, these findings provide a structural role for IsdBN1 in enhancing the rate of extraction of metHb heme by the IsdB NEAT 2 domain.

15The discovery that methylotrophic bacteria can utilize lanthanides as catalysts for methanol 16 metabolism has opened new areas of biology and biochemistry. Recent studies of lanthanide-17 dependent enzymes have focused on biochemical and kinetic properties or the regulation of 18 encoding genes. Kinetic analysis of a pyrroloquinoline quinone methanol dehydrogenase, XoxF1 19 (MexAM1_1746), from the model methylotroph Methylobacterium extorquens AM1 confirms 20 the use of different lanthanides as cofactors and formaldehyde as a product of methanol 21 oxidation, showing that not all XoxF MDH produce formate as the only end product in vivo. The 22 30 pyrroloquinoline quinone alcohol dehydrogenase ExaF (MexAM1_1139), but not XoxF1, can 31 reduce formaldehyde toxicity when lanthanides are present, providing evidence of a role for 32ExaF during lanthanide-dependent methylotrophy. We conclude from these results that 33 lanthanide-dependent methylotrophy is more efficient than calcium-dependent methylotrophy 34 in M. extorquens AM1, and that this change is due, at least in part, to the lanthanide-dependent 35 enzymes XoxF1 and ExaF. 36 37 IMPORTANCE 38 Lanthanides serve as cofactors for pyrroloquinoline quinone containing alcohol dehydrogenase 39 enzymes in methylotrophic bacteria. The present study addresses a fundamental gap in our 40 understanding of how lanthanides impact metabolism, including a detailed assessment of the 41 metabolic modifications to accommodate enhanced efficiency during methylotrophy. Kinetic 42 characterization of XoxF1 provides a detailed description of the impact of diverse lanthanides 43 on catalytic function for a lanthanide-dependent methanol dehydrogenase. We further show 44 that the lanthanide-dependent ethanol dehydrogenase ExaF can oxidize formaldehyde in vivo, 45 revealing complementary roles for these enzymes. This study provides novel insight into the 46 effects of lanthanides on bacterial metabolism, highlighting the implementation of multiple, 47 redundant and complementary oxidation systems. 48 49 53 5). Thus far, Ln-ADH can be grouped by their phylogeny and primary substrate as either XoxF-54 type methanol dehydrogenases (MDH) or ExaF-type ethanol dehydrogenases (EtDH). Reports 55 have provided evidence for XoxF having roles as both a periplasmic methanol and 56 formaldehyde-oxidation system (6) and as a regulator of expression of the calcium (Ca) 57 dependent MxaFI MDH (6, 7). MxaFI MDH has been considered the canonical primary catalyst 58 for methanol oxidation in Gram-negative methylotrophs (8, 9). MxaFI is a heterotetramer that 59 contains PQQ as a prosthetic group and coordinates a calcium ion (10-12). The discovery that 60 Ln are incorporated into the active site of XoxF MDH in place of Ca, allowing catalytic function, 61 has prompted the reexamination of methanol oxidation in methylotrophic bacteria (3, 13, 14). 62 In addition, we reported the first Ln-dependent EtDH ExaF, showing that Ln can impact multi-63 carbon as well as one-carbon metabolism (5). T...

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C. elegans is exposed to many different bacteria in its environment, and must distinguish pathogenic from nutritious bacterial food sources. Here, we show that a single exposure to purified small RNAs isolated from pathogenic Pseudomonas aeruginosa (PA14) is sufficient to induce pathogen avoidance, both in the treated animals and in four subsequent generations of progeny. The RNA interference and piRNA pathways, the germline, and the ASI neuron are required for bacterial small RNA-induced avoidance behavior and transgenerational inheritance. A single non-coding RNA, P11, is both necessary and sufficient to convey learned avoidance of PA14, and its C. elegans target, maco-1, is required for avoidance. A natural microbiome Pseudomonas isolate, GRb0427, can induce avoidance via its small RNAs, and the wild C. elegans strain JU1580 responds similarly to bacterial sRNA. Our results suggest that this ncRNA-dependent mechanism evolved to survey the worm's microbial environment, use this information to make appropriate behavioral decisions, and pass this information on to its progeny.

Animals face both external and internal dangers: pathogens threaten from the environment, and unstable genomic elements threaten from within. Previously, we discovered that C. elegans protects itself from pathogens by “reading” bacterial small RNAs and using this information to both induce avoidance and transmit memories for several generations. Here we found that these memories can be transferred to naïve animals via Cer1 retrotransposon-encoded capsids. Cer1 functions at the step of transmission of information from the germline to neurons, and is required for C. elegans’ learned avoidance ability and for mothers to pass this information on to progeny. The presence of the Cer1 retrotransposon in wild C. elegans strains correlates with the ability to learn and inherit small RNA-induced pathogen avoidance. Together, these results suggest that C. elegans has co-opted a potentially dangerous retrotransposon to instead protect itself and its progeny from a common pathogen through its inter-tissue signaling ability, hijacking this genomic element for its own adaptive immunity benefit.

Epidemiologic studies have linked the use of aspirin to a decline in chronic inflammation that underlies many human diseases, including some cancers. Aspirin reduces the levels of cyclooxygenase-mediated pro-inflammatory prostaglandins, promotes the production of proresolution molecules, and triggers the production of anti-inflammatory electrophilic mono-oxygenated (EFOX) lipid mediators. We investigated the effects of aspirin in fruit fly models of chronic inflammation. Ectopic Toll/NF-κB and JAK/STAT signaling in mutant D. melanogaster results in overproliferation of hematopoietic blood progenitors resulting in the formation of granuloma-like tumors. Ectopic JAK-STAT signaling also leads to metabolic inflammation. We report that aspirin-treated mutant flies experience reduction in metabolic inflammation, mitosis, ectopic immune signaling, and macrophage infiltration. Moreover, these flies synthesize 13-HODE, and aspirin triggers 13-oxoODE (13-EFOX-L 2) production. Providing the precursor of 13-HODE, linoleic acid, or performing targeted knockdown of the transcription factor STAT in inflammatory blood cells, boosts 13-EFOX-L 2 levels while decreasing metabolic inflammation. Thus, hematopoietic cells regulate metabolic inflammation in flies, and their effects can be reversed by pharmaceutical or dietary intervention, suggesting deep phylogenetic conservation in the ability of animals to resolve inflammation and repair tissue damage. These findings can help identify novel treatment targets in humans.