RESUMEN
Statoliths are the only hard structures in the gelatinous bell of most scyphozoan medusae and investigations on these structures could promote investigations of the understudied population dynamics and phylogeny of jellyfish. We examined the statoliths of Aurelia aurita jellyfish of different ages by light microscopic and microtomographic measurements supplemented by scanning electron microscopy. The morphometric analyses confirmed that statolith numbers and sizes increase during jellyfish development and revealed that newly-formed statoliths had similar shapes that may change during statolith growth. Nevertheless, most statoliths had a typical compact rod shape with an aspect ratio of 1-2.5 at all ages and we suggest that the composition of statolith shapes may be taxa specific. We developed a new approach allowing exact measurements of statolith growth for the first time. The application of calcein as a fluorescent marker resulted in clear fluorescent lines within the statoliths, allowing calculations of the statolith side face growth increments (0.1 µm/day; n=252). A single-crystal analysis revealed that the calcein incubation did not affect the statolith crystal structure. In conclusion, calcein labeling is an excellent method to follow the growth of bassanite statoliths.
RESUMEN
Jellyfish have an increasing impact on marine ecology. Cnidocysts bearing stinging cells afford, amongst others, prey capture and defence. Several different types of stinging capsules are found in one species and they are supposed to have specific functions, e.g. paralysing prey or adhering to it. Due to these assumed different roles of the capsules, it is suggested that toxins, which are contained in the capsules, differ in composition. Analysis of distinct types of nematocysts requires an appropriate method for the separation of the different types. Mixtures of types of nematocysts were obtained of two species of jellyfish, Aurelia aurita and Cyanea lamarckii, by maceration of the tissue. These mixtures were treated with a method called laser microdissection and pressure catapulting (LMPC). Optimized maceration methods, which were firstly introduced as a method for this purpose, in conjunction with optimized LMPC parameters lead to sufficient amounts of separated capsules of individual types for subsequent mass-spectrometric analyses. In case of A. aurita, the resulting mass spectra had some constituents in common, whereas in the overall pattern, the two distinct nematocyst types differed.
Asunto(s)
Venenos de Cnidarios/química , Proteínas/química , Escifozoos/citología , Animales , Rayos Láser , Espectrometría de MasasRESUMEN
Scyphomedusae use inorganic crystals (statoliths) for gravity sensing. The organs which contain the statoliths are called rhopalia. Rhopalia of five different species of the three different orders of the class Scyphozoa were studied with high-end solid-state chemical methods to elucidate the crystallographic nature of the biomineral: synchrotron powder diffraction, synchrotron single-crystal diffraction, synchrotron microtomography, scanning electron microscopy, and energy dispersive X-ray spectroscopy. Each rhopalium contains a large number of statoliths in an ordered way. The statoliths of all species consist of calcium sulfate hemihydrate, a water-deficient phase. This is remarkable for sea-living organisms consisting mostly of water. The phylogenetic relationships within the class Scyphozoa are discussed.
Asunto(s)
Sulfato de Calcio/química , Cnidarios/química , Animales , Cnidarios/anatomía & histologíaRESUMEN
Synchrotron-radiation-based computer microtomography (SRmicroCT) was applied to three biomineralised objects First, embryonic snails of the freshwater snail Biomphalaria glabrata, second, rhopalia (complex sense organs) of the medusa Aurelia aurita, and third, human teeth. The high absorption contrast between the soft tissue and mineralised tissues, i.e. the shell in the first case (consisting of calcium carbonate) and the statoliths in the second case (consisting of calcium sulphate hemihydrate), makes this method ideal for the study of biomineralised tissues. The objects can be non-destructively studied on a micrometre scale, and quantitative parameters like the thickness of a forming a snail shell or statolith crystal sizes can be obtained on a length scale of 1-2 mum. Using SRmicroCT, the dentin-enamel border can be clearly identified in X-ray dense teeth.