What about the males? the C. elegans sexually dimorphic nervous system and a CRISPR-based tool to study males in a hermaphroditic species

Abstract

Sexual dimorphism is a device that supports genetic diversity while providing selective pressure against speciation. This phenomenon is at the core of sexually reproducing organisms. Caenorhabditis elegans provides a unique experimental system where males exist in a primarily hermaphroditic species. Early works of John Sulson, Robert Horvitz, and John White provided a complete map of the hermaphrodite nervous system, and recently the male nervous system was added. This addition completely realized the vision of C. elegans pioneer Sydney Brenner: a model organism with an entirely mapped nervous system. With this 'connectome' of information available, great strides have been made toward understanding concepts such as how a sex-shared nervous system (in hermaphrodites and males) can give rise to sex-specific functions, how neural plasticity plays a role in developing a dimorphic nervous system, and how a shared nervous system receives and processes external cues in a sexually-dimorphic manner to generate sex-specific behaviors. In C. elegans, the intricacies of male-mating behavior have been crucial for studying the function and circuitry of the male-specific nervous system and used as a model for studying human autosomal dominant polycystic kidney disease (ADPKD). With the emergence of CRISPR, a seemingly limitless tool for generating genomic mutations with pinpoint precision, the C. elegans model system will continue to be a useful instrument for pioneering research in the fields of behavior, reproductive biology, and neurogenetics.

Tracking N- and C-termini of C. elegans polycystin-1 reveals their distinct targeting requirements and functions in cilia and extracellular vesicles

“…LOV-1 and PKD-2 are required for male mating behavior and act in the same genetic pathways [ 20 ]. Here we examined male response behavior to hermaphrodite contact and determined male mating efficiency, the latter measures the number of cross progeny sired by males [ 38 , 39 ]. We examined response behavior of the lov-1(C2181S) mutant compared to the deletion mutants of lov-1(sy582) and pkd-2(sy606 ) [ 19 , 20 ].…”

Tracking N- and C-termini of C. elegans polycystin-1 reveals their distinct targeting requirements and functions in cilia and extracellular vesicles

“…LOV-1 and PKD-2 are required for male mating behavior and act in the same genetic pathways [20]. Here we examined male response behavior to hermaphrodite contact and determined male mating efficiency, the latter measures the number of cross progeny sired by males [27, 28]. We examined response behavior of the lov-1(C2181S, GPS) mutant compared to the null deletion mutants of lov-1(sy582) and pkd-2(sy606) [19, 20].…”

“…The immobile, severely unc oordinated unc-52 hermaphrodites are easy targets for males while actively moving dpy-17 hermaphrodites are more difficult mating targets. These unc-52 and dpy-17 mating partners discern differing levels of phenotype severity [28]. The GPS mutant lov-1(C2181S) displayed mating efficiency defects of differing severity.…”

“…LOV-1 and PKD-2 are required for male mating behavior and act in the same genetic pathways [20]. Here we examined male response behavior to hermaphrodite contact and determined male mating efficiency, the latter measures the number of cross progeny sired by males [27,28].We examined response behavior of the lov-1(C2181S, GPS) mutant compared to the null deletion mutants of lov-1(sy582) and pkd-2(sy606) [19,20]. We confirmed that the double-tagged CRISPR mSC::LOV-1::mNG strain was wild type for male contact response to hermaphrodites (Fig 3D), indicating that the double-tagged LOV-1 in the CRISPR edited strain is functional.…”

Stearoyl-CoA desaturases sustain cholinergic excitation and copulatory robustness in metabolically aging C. elegansmales

“…To generate the mutation of him-5 ( e1490 ), a hundred 5- to 10-hour-old adult fat-7 ( lf ) hermaphrodites were microinjected with 50 ng/μL of the CRISPR/Cas9 plasmids, and 50 ng/μL of the oligo repair template. Others have shown the use of an oligo 161 bp long for CRISPR generated him-5 ( e1490 ) ( Walsh et al., 2020 ). In the F2 and F3 generation, males were picked and allowed to mate into fat-7 ( lf ) hermaphrodites.…”