Influence of selected plant amines on probing behaviour of bird cherry-oat aphid (Rhopalosiphum padi L.).

The study aimed to quantify the influence of common plant polyamines and tyramine on probing behaviour in the bird cherry-oat aphid (Rhopalosiphum padi L.). Electrical penetration graphs (DC) were used to monitor the probing and feeding behaviour of R. padi exposed to the amines agmatine, cadaverine, putrescine, spermidine, spermine and tyramine. The study results showed that the analyzed amines tended to shorten the stylet activity of aphids in the gels (as indicated by the g-C pattern), prolong the duration of non-probing behaviour (g-np pattern) and decrease salivation into the gels (g-E1pattern) and ingestion from the gels (g-G pattern). The 10 mM concentration of the studied amines, especially cadaverine, reduced or completely inhibited aphid ingestion. The obtained results demonstrate that plant amines participate in plant defence responses to R. padi through disturbance of its probing behaviour and the intensity of such effects is concentration dependent.

Changes in activity of lysine decarboxylase in winter triticale in response to grain aphid feeding.

Changes in lysine decarboxylase (LDC) activity caused by Sitobion avenae (F.) feeding on two winter triticale cultivars (cvs) were studied. The aphid fecundity and values of intrinsic rate of natural increase showed that cv Witon was less susceptible to S. avenae than cv Tornado. The grain aphid feeding on more susceptible triticale caused a decrease in the LDC activity, with exceptions of root tissues after two weeks of the feeding. In case of less susceptible cv Witon reduction of the LDC activity was observed only during initial period of S. avenae feeding. Later the aphid infestation induced activity of the LDC within tissues of cv Witon.

Resistance of cereals to aphids: The interaction between hydroxamic acids and UDP-glucose transferases in the aphidSitobion avenue (Homoptera: Aphididae).

UPD-glucose transferases are found in the cytosolic and microsomal fractions of the grain aphidSitobion avenae F. Gel filtration and SDSPAGE revealed that the microsomal fraction contained several forms of the enzyme. The molecular weights of the three most active fractions might be 68,000, 66,000, and 36,500. There was a negative correlation between the enzymes' activity in extracts of aphids and the concentration of DIMBOAaglucone in the winter wheat variety fed on by the aphid. A strong inhibition of the activity of the UPD-glucose transferases was observedin vitro at a concentration of DIMBOA as low as 0.01 mM. There was a greater activity of the enzymes in aphids fed on seedlings of susceptible than on moderately resistant wheat cultivars. Prolonged feeding on resistant cultivars resulted in a further reduction in the activity of the aphid's enzymes. The significance for cereal aphids of the role of their UDP-glucose tranferases in the detoxification of plant allelochemicals and adaptation to resistant varieties of cereals is discussed.

Effects of cold, starvation and immobilization on the composition of acid-soluble nuclear proteins in chicken liver.

Nuclear proteins soluble in 0.2 M sulphuric acid were isolated from the liver of three groups of hens subjected for 60 hours to starvation, immobilization or cold exposure. The obtained proteins were separated by means of one-dimensional and two-dimensional electrophoresis on polyacrylamide gel. It was observed that this exposure of the birds to stress caused no qualitative changes in liver nuclear proteins. Histones, histone-like proteins - M1, M2, M3, uM1, HMG 1 and 2 proteins, and a large group of non-histone protein fractions gave nearly identical patterns. However, several components of nuclear proteins were found whose quantity changed in the liver of the birds subjected to stress. These changes were observed in a protein with molecular weight about 27 000 daltons and two proteins weighing over 100 000 daltons.