VARIATION OF PROTEIN PROFILE AMONG CONSECUTIVE STINGS OF THE SCORPION PARABUTHUS LEIOSOMA (FAMILY: BUTHIDAE) FROM EGYPT, SUPPORTS THE VENOM-METERING HYPOTHESIS IN SCORPIONS.

Scorpions use their venom to immobilize prey items and defend themselves against predators. Scorpion venom is a complex mixture composed of a wide array of substances such as salts, small molecules, peptides, and proteins. During analysis of the prey capture behavior of the scorpion Parabuthus leiosoma, we noticed that the scorpion stings the prey several successive stings in different specific regions. The stings started with ventral surface of the abdomen followed by thorax, shoulders and finally the head. This finding raised the possibility that the scorpion might use the venom with different composition in different contexts. To check this possibility, venom was collected as sequential drops (stings) by electrical stimulation (20 Volt) of the telson of the Parabuthus leiosoma. Protein content was determined by spectrophotometer using total protein KIT. The results showed marked variation of the total protein among the consecutive stings of each of the investigated scorpions. To go further, the protein profiles for all the collected stings were analyzed separately using 10% SDS-polyacrylamide electrophoresis (SDS-PAGE). Similarly, differences were observed among the stings, not only in the number of the protein bands, but also in the intensity of the bands. Thus, these results indicated that different venom components are unequally represented among consecutive stings supporting the venom-metering hypothesis.