Food Search Strategy Changes in Caenorhabditis elegans under Chronic Starvation Conditions

Non-coding RNA regulatory networks underlying intestinal degradation in Apostichopus japonicus under starvation stress: Insights from transcriptome analysis

Starvation stress is one of the most common environmental challenges faced by aquatic animals, often leading to compensatory growth, a widespread phenomenon in the animal kingdom, especially among aquatic species. The sea cucumber (Apostichopus japonicus), a key marine economic species in China, has been shown to utilize long non-coding RNAs (lncRNAs) in responding to environmental changes, pathogen infections, and tissue regeneration. In this study, strand-specific high-throughput sequencing was employed to analyze transcriptomic data from degenerated intestines of A. japonicus under starvation conditions. High-quality lncRNAs were identified and classified, and key differentially expressed mRNAs and lncRNAs associated with intestinal degradation were screened. A gene interaction network model based on the competing endogenous RNA (ceRNA) theory was then constructed. The analysis revealed that the "AjSOX9/Aja-miR-2012-5p/MSTRG.2956.1 and MSTRG.5699.1" axes, as well as the "AjWNT9B/Aja-miR-200-3p/MSTRG.19757.1 and MSTRG.21788.1" axes, play significant roles in degraded intestines and may promote intestinal regeneration during compensatory growth. Additionally, the "AjFABP2/Aja-miR-9-5p/MSTRG.9667.1" axis appears to regulate energy metabolism under starvation stress. These findings provide valuable insights into the non-coding gene regulatory networks in invertebrates under starvation stress and offer a scientific foundation for developing stress-resistant sea cucumber strains, contributing to the sustainable development of the sea cucumber aquaculture industry.

Satiety, TAX-4, and OSM-9 Tune the Attraction of C. elegans Nematodes to Microbial Fermentation Products

Animals are sensitive to selective pressures associated with nutrient acquisition, underscoring the evolutionary significance of chemosensation in foraging and its intersection with satiety. For the model nematode Caenorhabditis elegans, isoamyl alcohol (3-methyl-1-butanol) and 2-methyl-1-butanol are produced by microbial fermentation and present in bacterial food sources collected from the natural environments. Both compounds, which are structural isomers of one another, elicit strong attraction in laboratory settings. Using laboratory chemotaxis assays, we show that starvation attenuates attraction to both compounds. Well-fed C. elegans is largely insensitive to the biosynthetic precursors of both alcohols, with the exception of 4-methyl-2-oxovaleric acid, which is a mild repellent. C. elegans chemosensation relies on expression of tax-4 cyclic nucleotide-gated (CNG) and osm-9 transient receptor potential, vanilloid (TRPV) ion channels and animals lacking both genes are taste- and smell-blind. Animals lacking tax-4 fail to attract isoamyl alcohol and 2-methyl-1-butanol and those lacking osm-9 exhibit stronger attraction than the wild-type. Starvation not only attenuates attraction, but also enhances repulsion to 4-methyl-2-oxovaleric acid and uncovers repulsion in tax-4 mutants absent in their well-fed counterparts. Collectively, these findings implicate satiety in regulating response strength, tax-4-dependent chemotaxis in attraction to isoamyl alcohol and 2-methyl-1-butanol, and osm-9-dependent chemotaxis in suppressing responses to biosynthetic precursors.

Food deprivation changes chemotaxis behavior in Caenorhabditis elegans

Exploring for food is important in food-deprived condition. Chemotaxis is one of the important behaviors to search food. Although chemotactic strategies in C. elegans have been well investigated: the pirouette and the weathervane strategies, the change of the chemotactic strategy by food deprivation is largely unclear. Here, we show the change of chemotactic strategy by food deprivation, especially for isoamyl alcohol. To compare chemotaxis under different food-deprivation period, we showed that worms change their chemotactic behaviors by food deprivation. The worms with 1-h food-deprivation change the weathervane strategy. On the other hand, 6-h food deprived animals change the pirouette strategy. These results demonstrate that worms change chemotactic strategy different way depend on period of food deprivation.