Highly-resolving two-dimensional electrophoresis for the study of insect proteins

In this paper, we describe methods for isolation, purification and solubilization of insect proteins from various tissues, including lipid-rich fat body. An Australian locust, Oedaleus australis, and its associated dipteran parasite, Trichopsidea oestracea, provided the protein samples. Protein samples of locust fat body, haemolymph and body wall as well as parasite whole-body extracts were isolated and purified of lipids and salts using chloroform-methanol extraction. Proteins were solubilized using two types of enhanced solubilizing solutions and arrayed using two-dimensional electrophoresis. We demonstrated substantial differences between the body wall protein spectra of normal locusts and those parasitized by T. oestracea. Proteins more abundant in parasitized locusts include two 70 kDa proteins with an isoelectric point (pI) of about 5.5, one approximately 55 kDa protein cluster with a pI of about 4.7 and three 40 kDa proteins with pI values of around 5.6. Proteins that decreased in parasitized locusts include a group of 45 kDa proteins with pI values between 6 and 6.8, and a cluster of 22 to 23 kDa proteins with pI values of approximately 5.4 and 5.6.