An analysis of the partial metabolic derepression of sea urchin eggs by ammonia: the existence of independent pathways

Incubation of unfertilized eggs in ammonia has been reported to initiate such late responses to fertilization as K⁺-conductance, DNA synthesis, chromosome condensation and cytoplasmic mRNA polyadenylation. It does not initiate such early responses as Na⁺-influx and the cortical reactions. We have further analyzed this metabolic derepression and find that ammonia activation does not result in the early respiratory burst and also does not initiate the late activation of Na⁺-dependent amino acid transport. Protein synthesis is increased, similar to that following normal fertilization. This indicates that augmentation of protein synthesis is causally linked neither to the earlier Na⁺-influx, cortical reactions, and respiratory burst nor to the later activation of amino acid transport. The temporal correlation between activation of transport and increased protein synthesis is therefore coincidental. The association between increased protein synthesis and establishment of K⁺-conductance was analyzed by abolishing K⁺-conductance through acidification of the sea water. This did not affect protein synthesis, indicating that K⁺-conductance and protein synthesis are also not causally linked.There is also no obligate link between protein synthesis and chromosome condensation. Incubation in low concentrations of ammonia results in increased protein synthesis but not chromosome condensation. Higher ammonia concentrations cause chromosome condensation but with no further increase in rate of protein synthesis. This suggests a concentration-dependent hierarchy of activation.These results are consistent with the concept that the late fertilization changes are not causally linked and proceed independently of each other. As we have not been able to disassociate the early changes, they may be obligately linked and dependent on each other.     

Thoracic splenosis. Diagnosis of a case by fine needle aspiration cytology

Fine needle aspiration cytology was used to study chest wall nodules in a patient who presented with fever, cough, pleuritic chest pain and cytomegalovirus infection and who had a previous history of abdominal trauma. The finding of splenic red pulp and white pulp in the aspirate, combined with the results of a radionucleotide liver-spleen scan, led to a diagnosis of thoracic splenosis, a relatively rare condition. Splenosis is thought to result from transplantation of splenic tissue after trauma and may provide some added protection against certain infectious conditions, both of which were present in this case.