Otolith mass asymmetries in the utricle and saccule of flatfish.

The otolith mass of the saccules and utricles of plaice, Pleuronectes platessa (n = 39) and turbot, Psetta maxima (n = 21) was measured using an electronic microbalance. In the right-eyed plaice, the left utricular otoliths were found to be significantly heavier than the right (p < 0.0001), whereas no significant difference was found between left and right saccular otoliths (p < 0.751). In the left-eyed turbot, both the right utricular and saccular otoliths were found to be significantly heavier (in both cases, p < 0.0001). While the gene and regulative protein responsible for the peripheral biomineralisation process have been identified, it remains unclear how the symmetry between the right and left otoliths in fish species is regulated. Here it is likely that an additional central mechanism is involved. It must be assumed that similar processes govern the systematic asymmetry observed in flatfish such as the plaice and turbot. Taken together these findings are strongly suggestive of concomitant CNS modification and metamorphic plasticity, presumably represented in genetic code.

Loss of serum and glucocorticoid-regulated kinase 3 (SGK3) does not affect proliferation and survival of multiple myeloma cell lines.

Multiple myeloma (MM) is a generally fatal plasma cell cancer that often shows activation of the phosphoinositide 3-kinase/Akt (PI3K/Akt) pathway. Targeted pharmacologic therapies, however, have not yet progressed beyond the clinical trial stage, and given the complexity of the PI3K/Akt signalling system (e.g. multiple protein isoforms, diverse feedback regulation mechanisms, strong variability between patients) it is mandatory to characterise its ramifications in order to better guide informed decisions about the best therapeutic approaches. Here we explore whether serum and glucocorticoid-regulated kinase 3 (SGK3), a potential downstream effector of PI3K, plays a role in oncogenic signalling in MM cells--either in concert with or independent of Akt. SGK3 was expressed in all MM cell lines and in all primary MM samples tested. Four MM cell lines representing a broad range of intrinsic Akt activation (very strong: MM.1s, moderate: L 363 and JJN-3, absent: AMO-1) were chosen to test the effects of transient SGK3 knockdown alone and in combination with pharmacological inhibition of Akt, PI3K-p110α, or in the context of serum starvation. Although the electroporation protocol led to strong SGK3 depletion for at least 5 days its absence had no substantial effect on the activation status of potential downstream substrates, or on the survival, viability or proliferation of MM cells in all experimental contexts tested. We conclude that it is unlikely that SGK3 plays a significant role for oncogenic signalling in multiple myeloma.

Experimentally induced motion sickness in fish: possible role of the otolith organs.

OBJECTIVE: Although the occurrence of motion sickness is largely attributed to sensory conflict, the reasons for the highly variable inter-individual susceptibility to motion sickness remain unclear. One cause may be asymmetry between otoconial masses in the right and left inner ear. This hypothesis has been supported by experiments in fish under conditions of prolonged weightlessness and parabolic flight. In swordtail fish (Xiphophorus helleri) we examined the extent to which a Coriolis force environment, which has a strong motion sickness-triggering effect, disturbs swimming behaviour or produces motion sickness. MATERIAL AND METHODS: In a sealed aquarium, fish (n = 22) were subjected to Coriolis stimulation by constant vertical axis rotation, combined with pendular oscillation around a horizontal axis. RESULTS: Initially, at low stimulus intensity, all fish showed active compensatory swimming behaviour. However, while the majority (n = 19) maintained active compensation movements at higher stimulus levels, the others (n = 3) entered a passive uncoordinated state, from which they recovered again after reduction of stimulus intensity. On examination of the otoconial mass, we found asymmetries between the right and left utricles in all three cases and between the saccules in one case. CONCLUSION: We conclude that a lateral preponderance of the otoconial masses in the utricle or saccule promotes motion sickness under experimental conditions. The utricle appears to play a more important role in this than the saccule.