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Results of experiments conducted on ink recovered from the squid Sepioteuthis australis indicate that there is no epinephrine or protein naturally present in the ink as it would be ejected in vivo. Protein content was effectively zero when ink was syringed from the duct end of the ink sac of freshly killed animals. By contrast, there were proteins in samples collected from dead specimens where ink was collected by a stripping method. From these samples, a single large molecular weight protein was identified as having tyrosinase activity. Digestion of syringed ink did not yield signs of melanin-bound proteins. Analysis of supernatants after centrifugation of squid ink consistently revealed the presence of DOPA, dopamine, and taurine, whereas epinephrine and nor-epinephrine were recorded from what was believed to be contaminated ink. Histological investigations of the ink sac revealed a compartmentalised glandular structure distal to the duct end. Closer observation of the glandular tissue showed that compartments increased in size as they matured and moved further into the lumen. It was concluded that the presence of epinephrine and tyrosinase (or a related protein) in the ink of S. australis could be attributed to rupturing of basal glandular compartments or contamination from other sources during the extraction process. [ABSTRACT FROM AUTHOR]

A simple method for purification of prothrombin from small quantities of plasma using electrophoresis in urea-acrylamide gel has been developed. The antiserum produced against this prothrombin has been used in a quantitative immunological assay for the measurement of prothrombin protein. The prothrombin concentration in 50 clinically healthy subjects has been measured and a normal range established. The assay is applicable to the study of normal and abnormal prothrombin, to in vivo studies of transfused prothrombin and to comparative animal studies. [ABSTRACT FROM AUTHOR]