Studies in detoxication. 45. β-Glucuronidase and arylsulphatase in the crop fluid of locusts

Studies in progress in this laboratory on the detoxication mechanisms of locusts involved an investigation of the occurrence of the enzymes ,-glucuronidase and arylsulphatase in these insects.It was soon discovered that a ,-glucuronide-decomposing enzyme and an arylsulphatase occurred in the crop liquor of these insects to an appreciable extent.For the estimation of the P-glucuronidase activity in the crop liquor the easily prepared quinolyl-8-glucuronide was found to be a convenient substrate, whilst arylsulphatase could readily be estimated by means of potassium 2-hydroxy-5nitrophenylsulphate as suggested by Robinson, Smith, Spencer & Williams (1952). EXPERIMENTAL Preparation of locust crop fluidand the enzyme solution Adult locusts of two species (Locusta migratoria migratori-oide8 and Schistocerca gregaria) were provided by the Anti- Locust Research Centre, British Museum (Natural History) and were kept on a diet of grass at 35-40° and relative humidity of 70 %.The crop fluid of the insects was obtained by picking them up by the thorax and placing the end of a blood pipette to their mouths.On handling in this way, the insects become excited and expel a large drop of clear brownish fluid which then runs into the pipette (for dis- cussion of the production of this drop of fluid see Chauvin, 1941).Volumes up to 0-04 ml.(average 0-02 ml.) could be obtained from each insect during a single manipulation.After a meal of grass the crop liquor is often greenish in colour, cloudy and more dilute than the brown liquor.For estimation on individual insects the crop fluid was used without dilution, whereas with the pooled fluid from several insects it was diluted with water as needed.Three specimens ofpooled crop fluid, on drying at 1100, were shown to contain 10-26, 10-57 and 10-3% of solid matter.The nitrogen content (Kjeldahl) of pooled material was 8-75 mg.N/ml.(two estimations).