During aging, etiologies of senescence cause multiple pathologies, leading to morbidity and death. To understand aging requires identification of these etiologies. For example, Caenorhabditis elegans hermaphrodites consume their own intestinal biomass to support yolk production, which in later life drives intestinal atrophy and ectopic yolk deposition. Yolk proteins (YPs; vitellogenins) exist as three abundant species: YP170, derived from vit-1–vit-5; and YP115 and YP88, derived from vit-6. Here, we show that inhibiting YP170 synthesis leads to a reciprocal increase in YP115/YP88 levels and vice versa, an effect involving posttranscriptional mechanisms. Inhibiting YP170 production alone, despite increasing YP115/YP88 synthesis, reduces intestinal atrophy as much as inhibition of all YP synthesis, which increases life span. By contrast, inhibiting YP115/YP88 production alone accelerates intestinal atrophy and reduces life span, an effect that is dependent on increased YP170 production. Thus, despite copious abundance of both YP170 and YP115/YP88, only YP170 production is coupled to intestinal atrophy and shortened life span. In addition, increasing levels of YP115/YP88 but not of YP170 increases resistance to oxidative stress; thus, longevity resulting from reduced vitellogenin synthesis is not attributable to oxidative stress resistance.

The nematode Caenorhabditis elegans exhibits rapid senescence that is promoted by the insulin/IGF-1 signalling (IIS) pathway via regulated processes that are poorly understood. IIS also promotes production of yolk for egg provisioning, which in post-reproductive animals continues in an apparently futile fashion, supported by destructive repurposing of intestinal biomass that contributes to senescence. Here we show that post-reproductive mothers vent yolk which can be consumed by larvae and promotes their growth. This implies that later yolk production is not futile; instead vented yolk functions similarly to milk. Moreover, yolk venting is promoted by IIS. These findings suggest that a self-destructive, lactation-like process effects resource transfer from postreproductive C. elegans mothers to offspring, in a fashion reminiscent of semelparous organisms that reproduce in a single, suicidal burst. That this process is promoted by IIS provides insights into how and why IIS shortens lifespan in C. elegans.

The bioenergetics of light-harvesting by photosynthetic antenna proteins in higher plants is well understood. However, investigation into the regulatory non-photochemical quenching (NPQ) mechanism, which dissipates excess energy in high light, has led to several conflicting models. It is generally accepted that the major photosystem II antenna protein, LHCII, is the site of NPQ, although the minor antenna complexes (CP24/26/29) are also proposed as alternative/additional NPQ sites. LHCII crystals were shown to exhibit the short excitation lifetime and several spectral signatures of the quenched state. Subsequent structure-based models showed that this quenching could be explained by slow energy trapping by the carotenoids, in line with one of the proposed models. Using Fluorescence Lifetime Imaging Microscopy (FLIM) we show that the crystal structure of CP29 corresponds to a strongly quenched conformation. Using a structure-based theoretical model we show that this quenching may be explained by the same slow, carotenoid-mediated quenching mechanism present in LHCII crystals.