A large close relative of C. elegans is slow-developing but not long-lived

Collagen peptides from sturgeon swim bladder prolong the lifespan and healthspan in Caenorhabditis elegans

BACKGROUND

Sturgeon is a popular aquaculture species in many countries. Its swim bladder is rich in collagen but has not yet been exploited scientifically.

RESULTS

Collagen peptides (CPs) prepared from sturgeon swim bladder by trypsinolysis had an average molecular weight of 528.5 Da and consisted of 407 peptides, 16.1% of the content of which was GFPGADGSAGPK. The CPs at 25 mg mL-1 extended the lifespan of Caenorhabditis elegans by 22.6%, which was significantly higher than the extension achieved by other hydrolysis methods and source materials. They also improved fitness-related traits (body size, motor capacity, oxidative stress, cell apoptosis, and epidermal barrier function), indicating prolonged healthspan. Transcriptome analysis showed that the effect was mediated by the mitogen-activated protein kinase pathway, which enhanced stress resistance, the insulin/IGF-1 pathway, which inhibited protein aggregation, and the NHR-80/FAT-6 pathway, which regulated lipid metabolism.

CONCLUSION

Collagen peptides from sturgeon swim bladder by trypsinolysis prolonged the lifespan and healthspan in C. elegans, and might be promising anti-aging agents. © 2024 Society of Chemical Industry.

Abalone peptide increases stress resilience and cost-free longevity via SKN-1-governed transcriptional metabolic reprogramming in C. elegans

A major goal of healthy aging is to prevent declining resilience and increasing frailty, which are associated with many chronic diseases and deterioration of stress response. Here, we propose a loss-or-gain survival model, represented by the ratio of cumulative stress span to life span, to quantify stress resilience at organismal level. As a proof of concept, this is demonstrated by reduced survival resilience in Caenorhabditis elegans exposed to exogenous oxidative stress induced by paraquat or with endogenous proteotoxic stress caused by polyglutamine or amyloid-β aggregation. Based on this, we reveal that a hidden peptide ("cryptide")-AbaPep#07 (SETYELRK)-derived from abalone hemocyanin not only enhances survival resilience against paraquat-induced oxidative stress but also rescues proteotoxicity-mediated behavioral deficits in C. elegans, indicating its capacity against stress and neurodegeneration. Interestingly, AbaPep#07 is also found to increase cost-free longevity and age-related physical fitness in nematodes. We then demonstrate that AbaPep#07 can promote nuclear localization of SKN-1/Nrf, but not DAF-16/FOXO, transcription factor. In contrast to its effects in wild-type nematodes, AbaPep#07 cannot increase oxidative stress survival and physical motility in loss-of-function skn-1 mutant, suggesting an SKN-1/Nrf-dependent fashion of these effects. Further investigation reveals that AbaPep#07 can induce transcriptional activation of immune defense, lipid metabolism, and metabolic detoxification pathways, including many SKN-1/Nrf target genes. Together, our findings demonstrate that AbaPep#07 is able to boost stress resilience and reduce behavioral frailty via SKN-1/Nrf-governed transcriptional reprogramming, and provide an insight into the health-promoting potential of antioxidant cryptides as geroprotectors in aging and associated conditions.

C. elegans ageing is accelerated by a self-destructive reproductive programme

In post-reproductive C. elegans, destructive somatic biomass repurposing supports production of yolk which, it was recently shown, is vented and can serve as a foodstuff for larval progeny. This is reminiscent of the suicidal reproductive effort (reproductive death) typical of semelparous organisms such as Pacific salmon. To explore the possibility that C. elegans exhibits reproductive death, we have compared sibling species pairs of the genera Caenorhabditis and Pristionchus with hermaphrodites and females. We report that yolk venting and constitutive, early pathology involving major anatomical changes occur only in hermaphrodites, which are also shorter lived. Moreover, only in hermaphrodites does germline removal suppress senescent pathology and markedly increase lifespan. This is consistent with the hypothesis that C. elegans exhibit reproductive death that is suppressed by germline ablation. If correct, this would imply a major difference in the ageing process between C. elegans and most higher organisms, and potentially explain the exceptional plasticity in C. elegans ageing.

Opposing directions of stage-specific body shape change in a close relative of C. elegans

Background

Body size is a fundamental organismal trait. However, as body size and ecological contexts change across developmental time, evolutionary divergence may cause unexpected patterns of body size diversity among developmental stages. This may be particularly evident in polyphenic developmental stages specialized for dispersal. The dauer larva is such a stage in nematodes, and Caenorhabditis species disperse by traveling on invertebrate carriers. Here, we describe the morphology of a stress-resistant, dauer-like larval stage of the nematode Caenorhabditis inopinata, whose adults can grow to be nearly twice as long as its close relative, the model organism C. elegans.

Results

We find that a dauer-like, stress-resistant larval stage in two isolates of C. inopinata is on average 13% shorter and 30% wider than the dauer larvae of C. elegans, despite its much longer adult stage. Additionally, many C. inopinata dauer-like larvae were ensheathed, a possible novelty in this lineage reminiscent of the infective juveniles of parasitic nematodes. Variation in dauer-like larva formation frequency among twenty-four wild isolates of C. inopinata was also observed, although frequencies were low across all isolates (< 2%), with many isolates unable to produce dauer-like larvae under conventional laboratory conditions.

Conclusion

Most Caenorhabditis species thrive on rotting plants and disperse on snails, slugs, or isopods (among others) whereas C. inopinata is ecologically divergent and thrives in fresh Ficus septica figs and disperses on their pollinating wasps. While there is some unknown factor of the fig environment that promotes elongated body size in C. inopinata adults, the small size or unique life history of its fig wasp carrier may be driving the divergent morphology of its stress-resistant larval stages. Further characterization of the behavior, development, and morphology of this stage will refine connections to homologous developmental stages in other species and determine whether ecological divergence across multiple developmental stages can promote unexpected and opposing changes in body size dimensions within a single species.

Reproductive Suicide: Similar Mechanisms of Aging in C. elegans and Pacific Salmon

In some species of salmon, reproductive maturity triggers the development of massive pathology resulting from reproductive effort, leading to rapid post-reproductive death. Such reproductive death, which occurs in many semelparous organisms (with a single bout of reproduction), can be prevented by blocking reproductive maturation, and this can increase lifespan dramatically. Reproductive death is often viewed as distinct from senescence in iteroparous organisms (with multiple bouts of reproduction) such as humans. Here we review the evidence that reproductive death occurs in C. elegans and discuss what this means for its use as a model organism to study aging. Inhibiting insulin/IGF-1 signaling and germline removal suppresses reproductive death and greatly extends lifespan in C. elegans, but can also extend lifespan to a small extent in iteroparous organisms. We argue that mechanisms of senescence operative in reproductive death exist in a less catastrophic form in iteroparous organisms, particularly those that involve costly resource reallocation, and exhibit endocrine-regulated plasticity. Thus, mechanisms of senescence in semelparous organisms (including plants) and iteroparous ones form an etiological continuum. Therefore understanding mechanisms of reproductive death in C. elegans can teach us about some mechanisms of senescence that are operative in iteroparous organisms.

Methylglyoxal influences development of Caenorhabditis elegans via lin-41-dependent pathway

Methylglyoxal is a highly reactive dicarbonyl compound. It can be obtained either endogenously through biological enzymatic/non-enzymatic pathways or exogenously via the uptake of certain foods and beverages, such as Manuka honey. Studies about its biological properties are quite controversial, though the majority reported a positive association between methylglyoxal and certain pathologies. In this report, we tested if methylglyoxal can alter the development of animals using Caenorhabditis elegans as the in vivo model. Treatment of methylglyoxal at 0.1 and 1 mmol/L for 2 days significantly inhibited the development of Caenorhabditis elegans, particularly targeting the transition from L3 stage. Pharyngeal pumping rate, the food intake marker was also significantly reduced by methylglyoxal at both 0.1 and 1 mmol/L. Additionally, treatment of 0.1 mmol/L methylglyoxal increased, while 1 mmol/L methylglyoxal decreased the nematodes' average moving speed. The effect of methylglyoxal on development was in part due to the modulation of lin-41, which encodes a homolog of human TRIM71. The mutation of lin-41 could alleviate or abolish the effects of methylglyoxal on growth rate, body size, pumping rate and locomotive activity. In summary, these results suggested that methylglyoxal influenced the development of Caenorhabditis elegans, which is in part via the lin-41-dependent pathway.

Enhanced Healthspan in Caenorhabditis elegans Treated With Extracts From the Traditional Chinese Medicine Plants Cuscuta chinensis Lam. and Eucommia ulmoides Oliv

To uncover potential anti-aging capacities of Traditional Chinese Medicine (TCM), the nematode Caenorhabditis elegans was used to investigate the effects of Eucommia ulmoides and Cuscuta chinensis extracts, selected by screening seven TCM extracts, on different healthspan parameters. Nematodes exposed to E. ulmoides and C. chinensis extracts, starting at the young adult stage, exhibited prolonged lifespan and increased survival after heat stress as well as upon exposure to the pathogenic bacterium Photorhabdus luminescens, whereby the survival benefits were monitored after stress initiation at different adult stages. However, only C. chinensis had the ability to enhance physical fitness: the swimming behavior and the pharyngeal pumping rate of C. elegans were improved at day 7 and especially at day 12 of adulthood. Finally, monitoring the red fluorescence of aged worms revealed that only C. chinensis extracts caused suppression of intestinal autofluorescence, a known marker of aging. The results underline the different modes of action of the tested plants extracts. E. ulmoides improved specifically the physiological fitness by increasing the survival probability of C. elegans after stress, while C. chinensis seems to be an overall healthspan enhancer, reflected in the suppressed autofluorescence, with beneficial effects on physical as well as physiological fitness. The C. chinensis effects may be hormetic: this is supported by increased gene expression of hsp-16.1 and by trend, also of hsp-12.6.

Degradation of the Repetitive Genomic Landscape in a Close Relative of Caenorhabditis elegans

The abundance, diversity, and genomic distribution of repetitive elements is highly variable among species. These patterns are thought to be driven in part by reproductive mode and the interaction of selection and recombination, and recombination rates typically vary by chromosomal position. In the nematode Caenorhabditis elegans, repetitive elements are enriched at chromosome arms and depleted on centers, and this mirrors the chromosomal distributions of other genomic features such as recombination rate. How conserved is this genomic landscape of repeats, and what evolutionary forces maintain it? To address this, we compared the genomic organization of repetitive elements across five Caenorhabditis species with chromosome-level assemblies. As previously reported, repeat content is enriched on chromosome arms in most Caenorhabditis species, and no obvious patterns of repeat content associated with reproductive mode were observed. However, the fig-associated C. inopinata has experienced repetitive element expansion and reveals no association of global repeat density with chromosome position. Patterns of repeat superfamily specific distributions reveal this global pattern is driven largely by a few repeat superfamilies that in C. inopinata have expanded in number and have weak associations with chromosome position. Additionally, 15% of predicted protein-coding genes in C. inopinata align to transposon-related proteins. When these are excluded, C. inopinata has no enrichment of genes in chromosome centers, in contrast to its close relatives who all have such clusters. Forward evolutionary simulations reveal that chromosomal heterogeneity in recombination rate alone can generate structured repetitive genomic landscapes when insertions are weakly deleterious, whereas chromosomal heterogeneity in the fitness effects of transposon insertion can promote such landscapes across a variety of evolutionary scenarios. Thus, patterns of gene density along chromosomes likely contribute to global repetitive landscapes in this group, although other historical or genomic factors are needed to explain the idiosyncrasy of genomic organization of various transposable element taxa within C. inopinata. Taken together, these results highlight the power of comparative genomics and evolutionary simulations in testing hypotheses regarding the causes of genome organization.