Actinomycin D inhibits RNA synthesis on the lateral loops of newt lampbrush chromsomes. Partial inhibition does not provoke marked morphological alteration of ordinary lateral loops, most of which recover to the full their capacity for RNA synthesis within 2 days of treatment. However, occasional ordinary loops do not recover completely within the first few days after treatment, and in such loo...

A total of 5 nudibranch species are reported from the Norwegian coast for the first time (Doridoxa ingolfiana, Goniodoris castanea, Onchidoris sparsa, Eubranchus rupium and Proctonotus mucroniferus). In addition 10 species that can be considered rare in Norwegian waters are presented with new information (Lophodoris danielsseni, Onchidoris depressa, Palio nothus, Tritonia griegi, Tritonia linea...

The large bloom-forming flagellate Gonyostomum semen has been hypothesized to be inedible to naturally occurring zooplankton due to its large cell size and ejection of long slimy threads (trichocysts) induced by physical stimulation. In a grazing experiment using radiolabelled algae and zooplankton collected from lakes with recurring blooms of G. semen and lakes that rarely experience blooms, w...

To examine the hydrodynamic propulsion mechanism of a diving great crested grebe (Podiceps cristatus), the three-dimensional kinematics was determined by digital analysis of sequential video images of dorsal and lateral views. During the acceleration phase of this foot-propelled bird, the feet move through an arc in a plane nearly normal to the bird's line of motion through the water, i.e. the ...

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Newt oocytes were dissected under liquid paraffin and known volumes of clean nucleoplasm and cytoplasm were obtained from oocytes in different stages of oogenesis. The samples were digested in redistilled nitric acid, diluted with deionized water, and their Na and K contents were measured by flame spectrophotometry. The results were expressed as micro-equivalents of Na and K per millilitre of n...

Structure of the cuticle of Metadasynemoides cristatus (Chromadorida: Ceramonematidae) is examined by light, scanning, and transmission electron microscopy. The nematode has more than 600 annuli, and each annulus has eight cuticular plates. Eight longitudinal ridges, beginning on the cephalic capsule, extend the whole length of the body. Where a ridge traverses an annulus, it forms a complicate...