Caenorhabditis brenneri as a complementary model organism to C. elegans: Insights from ecological, molecular and comparative biology

The Caenorhabditis elegans is a well-established model in the advancement of cell and molecular biology, lead-compound discovery and multidisciplinary research. However, its sibling species C. brenneri, remains relatively underexplored despite its hyperdiverse genome and ecological significance. This study sought to discover sister species of C. elegans through ecological surveys, genetic characterization, and biological comparisons with C. elegans (N2), with the aim of positioning of wild isolates as complementary model organisms. Sampling was conducted across 11 distinct bio-ecological zones, followed by cultivation and independent propagation of bacterivorous nematodes. Distinct morphological traits with the amplification of ITS2 and 18s rRNA regions confirmed isolates of C. brenneri, Oscheus sp., and surprisingly, Tarantobrlus jeffdanielsi and Rhabditella axei. The genetic diversity analysis based on ITS2 sequences of C. brenneri isolates revealed that diversities and polymorphisms are consistent with neutral evolution rather than selection. A comparative analysis of C. elegans and wild C. brenneri isolates including lifespan, fecundity, thermo-tolerance, anthelmintic sensitivity and bacterial killing assay revealed that, compared to C. elegans N2 strain, C. brenneri isolates live longer, produce fewer eggs than C. elegans, exhibited higher survival under prolonged heat stress and significantly greater survival against bacteria and transient lethality in anthelmintics. This pioneering investigation confirms the availability of C. brenneri and other previously undiscovered nematodes in different regions of Bangladesh, outlines its evolutionary context, resilience to stressors and warns altered host adaptability. These findings highlight the potential of C. brenneri as a robust complementary model for research into species-specific responses to environmental or pathogenic stressors.