Na, K-ATP-ase and acetylcholinesterase activity of the membrane structures of the rat brain and spinal cord during the seizure process]

The activity of ATP-ase and acetylcholinesterase (AChE) in crude mitochondrial fraction (CMF) and microsomal fraction of rat brain cortex and the spinal cord was studied in clonic seizures evoked by electroshock and 5 min after them. Inhibition of the Na, K-ATP-ase activity of the CMF of the brain at the clonic phase of convulsions and an increase in the activity of this enzyme in all the fractions of the tissues under study at the postconvulsive period were revealed. The activity of Ca-ATP-ase in the CMF of the brain increased during the convulsions and decreased at the postconfulsive period. The activity of Mg-ATP-ase remained unchanged. The AChE activity, as a rule increased during the convulsions, and grew even more during the postconvulsive period; the spinal cord tissue displayed a reduction of the activation effect. A possibility of structural reconstructions in the excitable neuron membranes during the convulsive activity is discussed.     

The function of multi-pod aggregations of fish-eating killer whales (<Emphasis Type="Italic">Orcinus orca</Emphasis>) in Kamchatka,Far East Russia

In fish-eating North Pacific killer whales, large multi-pod aggregations of up to 100 animals often occur. These aggregations are thought to be reproductive gatherings where mating between members of different pods takes place. However, killer whales are social animals, and the role of these aggregations might also be establishing and maintaining social bonds between pods. Alternatively, it is also possible that multi-pod aggregations are in some way connected with foraging or searching for fish. In this study of killer whales in the western North Pacific, we describe multi-pod aggregations quantitatively and suggest their functional role in the life of fish-eating killer whales. We show that foraging is rare in multi-pod aggregations, whether inter-clan or intra-clan, and thus they are unlikely to play an important role in cooperative foraging. Socialising occurs more frequently in inter-clan rather than in intra-clan aggregations, which suggests the higher arousal level and possible mating during inter-clan aggregations. In summary, multi-pod aggregations of Kamchatka killer whales might be both reproductive assemblages and “clubs” of some kind in which whales gather to establish and maintain social bonds.     

Synthesis of (5Z,8Z,11Z,14Z)-18- and 19-azidoeicosa-5,8,11,14-tetraenoic acids and their [5,6,8,9,11,12,14,15-H8]-analogues through a common synthetic route

Total synthesis of (5Z,8Z,11Z,14Z)-18- and 19-azidoeicosa-5,8,11,14-tetraenoic acids and their [5,6,8,9,11,12,14,15-³H₈]-analogues via the corresponding p-toluenesulphonates is reported. This synthetic approach allows the preparation of radioactively labelled arachidonic acid derivatives following a common synthetic route. Activity assays indicated that 15-lipoxygenases may tolerate the azido group in the substrate binding pocket and thus, radioactively labelled azido compounds may be used as photo-affinity probes to investigate mechanistic features of eicosanoid biosynthesis.