Alanine aminotransferase in the three last larval instars of Barathra brassicae infected by Nosema plodiae

During three last larval instars of Barathra brassicae the alanine aminotransferase activity pattern exhibits two maxima which do not correspond with the maxima of activity of phosphatases and proteases. In the larvae infected by Nosema plodiae a different course of activity can be seen from the 5th day of infection. The activity pattern in the diseased larvae rises above that of a normal larva by 90% shortly before the last molt and reaches a maximum at the end of normal larval development. Alanine aminotransferase in the gut and in the fat body exhibits two main pH optima of activity, 8.0 and 9.5, respectively, and a low activity peak at pH 4.5. This last activity is not present in diseased animals. The temperature and pH inactivation are also described.