Electrophoretic study of enzymes from cereal aphid populations. I. Electrophoretic techniques and staining systems for characterising isoenzymes from six species of cereal aphids (Hemiptera: Aphididae)

Abstract

One-dimensional slab polyacrylamide gel electrophoretic techniques, staining systems and isoenzyme banding patterns for 14 soluble enzymes separated from crude homogenates of individuals of six species of cereal aphids {Sitobion avenae (F.), 5. fragariae (Wlk.), Metopolophium dirhodum (Wlk.), M. festucae (Theo.), Rhopalosiphum padi (L.) and R. maidis (Fitch)) are described. The value of the techniques and banding patterns to taxonomic and population genetic studies of these and other aphid species are briefly discussed. With the six species, it was possible to separate the different genera as well as individual species within genera. The enzymes found to be most useful for inter-generic and/or -specific separations were adenylate kinase (AK), esterase (EST), glucose-6-phosphate dehydrogenase (G-6-PDH), hexokinase (HK), malate dehydrogenase (MDH), peptidase (PEP), phosphatase (PHOS), phosphoglucomutase (PMG), 6-phosphogluconate dehydrogenase (6-PGD) and sorbitol dehydrogenase (SORDH), whilst glutamate oxaloacetate transaminase (GOT), a-glycerophosphate dehydrogenase (a-GPD), malic enzyme (ME) and peroxidase (POD) were of relatively little taxonomic use. There were no banding pattern differences between the various morphs of 5. avenae (first to fourthinstar nymphs, apterous and alate adults) using the 14 enzymes.

Genetic variability within and between English populations of the damson–hop aphid,Phorodon humuli(Hemiptera: Aphididae), with special reference to esterases associated with insecticide resistance

“…Carboxylesterases (EST) and enzymes from the 1987 samples (PEP, PHOS, GOT, SORDH, ME, HK; see below) were separated using 8 X 8 cm 6% polyacrylamide gel electrophoresis (PAGE) and stained as outlined in Loxdale et al (1983). The esterases of aphids appear to be partially inactivated when run on cellulose acetate (CA) plates (Loxdale & Brookes, unpublished observations), necessitating their separation using PAGE.…”

“…Subsequently for the other enzymes, because of its several advantages compared with PAGE, CA electrophoresis (Wynne et al, 1992) was performed using Helena Laboratories (UK) Ltd (Gateshead, Tyne and Wear, England) equipment. For polyacrylamide electrophoresis, aphids were homogenized individually in 10 JJ.1 homogenizing fluid (Loxdale et al, 1983) using a multiple homogenizing device (Brookes & Loxdale, 1985), whilst for CA electrophoresis, they were homogenized individually in 5-7 ul of homogenizing fluid within the wells of the Helena sample loading plate.…”

Iǹtraspecific variation in two species of Suillus from Scots pine (Pinus sylvestris L.) forests based on somatic incompatibility and isozyme analyses

“…The composition of the gel buffer (70-6 mM Tris-HCl, pH 7-8) and the electrode buffer (8-3 mM Tris-barbitone, pH 7-45) remained unchanged (Loxdale, Castanera & Brookes, 1983). After electrophoresis, gels were stained to visualize eight enzymes (van Loon, 1971;Loxdale et al, 1983;Sen & Hepper, 1986) which were reproducibly detected in preliminary gel runs of the Scandinavian control isolates. The following six enzymes were clearly resolvable in both fungal species; esterase (EST) (EC 3.1.1.1), acid phosphatase (ACP) (EC 3.1.3.2), peptidase (PEP) (EC 3.4.11), peroxidase (PER) (EC 1.11.1.7), glutamate oxaloacetate transaminase (GOT) (EC 2.6.1 .l)andhexokinase (HK) (EC 2.7.1.1).…”

On the Morphological and Genotypic Variations of Two Congeneric species of Banana Aphid Pentalonia (Homoptera: Aphididae) from India

“…Staining mixtu res were prepared accord ing to the procedure of Lo xdale et al [19] and Singh & Cunningham [20]. (Esterase: 50 ml of en zy me buffer, 50 mg substrate-naphthyl acetate, 0.6 ml acetone, 0.6 ml distilled water and 50 mg of Fast Garnet GBC salt stain; Malic dehydrogenase: 7.5 ml of 0.1M TRIS-HCl buffer, 62.5 ml double distilled water, 15 mg DL-malic acid, 10 mg NAD, 5 mg NBT and 10 mg PMS; Acid phosphatase: 50 ml of enzy me buffer, 60 mg α-naphthyl acid phosphate and 60 mg of Fast Garnet GBC salt stain).…”