Nanosecond-scale kinetics of nematocyst discharge

Functional characteristics of nematocysts found on the scyphomedusa Cyanea capillata

“…The kinetic energies estimated in this study were orders of magnitude less than the kinetic energy of discharged stenotele nematocysts (on the order of femto-versus microJoules; Nuchter et al, 2006). For the O-isorhizas, euryteles and birhopaloids, this is due to our large underestimates of initial velocities and, therefore, the tubule kinetic energies of these nematocysts are likely to be more similar to stenoteles than our data suggests.…”

“…However, the shafts (i.e. ; wide, barbed section of the discharged tubule adjacent to the nematocyst capsule) of the euryteles and birhopaloids were fully discharged within one video frame (0.004 s) and more than half of the tubules of Oisorhizas were also fully discharged within a frame and, therefore, for these nematocysts, our velocities represent the average velocity over the initial 4 milliseconds after discharge and are likely to be gross underestimates of initial velocities (Nuchter et al, 2006).…”

“…Beyond this, most of our current knowledge on prey capture by nematocysts is based upon studies which either relate the nematocyst assemblage found on a medusan species to its diet (Purcell and Mills, 1988;Carrette et al, 2002;Peach and Pitt, 2005), or studies using microscopy to examine preserved samples of nematocysts and their captured prey (Purcell, 1984;Heeger and Möller, 1987;Heeger et al, 1992;Östman and Hydman, 1997;Peach and Pitt, 2005). Due to the inherent difficulty in observing the fastest cellular process identified, few studies have directly observed and described the discharge properties of different types of nematocysts (Holstein and Tardent, 1984;Nuchter et al, 2006). Besides the limited number of studies that have documented discharge velocities of stenotele nematocysts (Holstein and Tardent, 1984; Fig.…”

“…A) intact tentacle with multiple batteries; B) close-up of individual battery from the tentacle; C) close-up of individual battery from the oral arm. Scale bars are 100 μm long in A and 10 μm long in B and C. Nuchter et al, 2006), no studies have documented or compared the basic properties of nematocyst tubules during discharge, including tubule velocity, path and length. Therefore, we do not know whether the tubules of similar types of nematocysts discharge similarly or whether their discharge properties are related to the nematocyst categories identified by taxonomists.…”

Proteome of Hydra Nematocyst

“…The molecular composition of the capsule comprises a highly dense collagenous polymer charged with an osmotic pressure of 150 bars (11,12). Nematocyst discharge, triggered by the mechanosensory cnidocil apparatus, is one of the fastest processes in biology and creates an impact on the harpoon-like expelled tubule comparable with technical bullets (1). Of the protein components constituting the nematocyst, only a small fraction has hitherto been defined.…”