10.17912/ECSM-MP67
Fechner, Sylvia
Sylvia
Fechner
Loizeau, Frédéric
Frédéric
Loizeau
Nekimken, Adam L
Adam L
Nekimken
Pruitt, Beth L
Beth L
Pruitt
Goodman, Miriam B
Miriam B
Goodman
The bodies of dpy-10(e128) are twice as stiff as wild type
microPublication Biology
2018
ResearchArticle
2018
DPY-10 is a collagen protein in the nematode's cuticle. Mutations in the dpy-10 gene induce various morphological changes that lead to animals with a dumpy or roller phenotype (Levy, Yang & Kramer, 1993). Here, we asked how such mutations affect body stiffness by comparing force-indentation curves in dpy-10(e128) and wild type worms. On average, dpy-10(e128) worms have a steeper force-indentation relationship, leading to a higher body stiffness (Fig 1.C). Average stiffness values were 2.5 0.9 N/m, SD, (n = 24) for dpy-10(e128) and 0.9 0.3 N/m, SD, (n = 25) for wild type (N2) hermaphrodites. Qualitatively, we observed that some of the dpy-10(e128) worms had a disrupted cuticle and their bodies spontaneously eviscerated after being immobilized to an agarose pad. Finally, we confirm the finding that dpy-10(e128) worms are shorter (Fig 1.D) and fatter (Fig 1.E) than wild type worms with an average body length of 712 68 µm (SD, n = 24) compared to wild type N2 worms 900 68 µm (SD, n = 25) and an average body width at the pharynx of 42 5.6 µm (SD, n = 24) compared to wild type N2 worms 36 4 µm (SD, n = 25) (Levy, Yang & Kramer, 1993). Panel F shows the Body relationship to scale.
From these results, we conclude that the bodies of dpy-10(e128) are twice as stiff as wild type: to reach the same indentation, a much higher force was necessary to be applied to dpy-10(e128) than to wild type worms (Fig 1. A). Prior measurements of body stiffness with the same method revealed that dpy-5(e61) worms are softer than wild type worms (Park et al. 2007). Thus, body shape does not predict body stiffness. Why is one Dpy animal softer than wild-type and another one stiffer? We propose that dpy-10 is stiffer than wild-type because it has an increased internal glycerol concentration and increased pressure, that is absent from dpy-5(e61) (Wheeler and Thomas 2006).