Anatomy and Phenylpropanoid Metabolism in the Incompatible Interaction of Lycopersicon esculentum and Cuscuta reflexa

A time-dependent correlation of anatomical and chemical defence reactions was shown during the incompatible reaction of tomato against the phanerogamic parasite Cuscuta reflexa. Microscopical analysis of the infection sites at the tomato stem revealed the elongation of epidermal, hypodermal and collenchymatic cells beneath the parasitic prehaustorium. After 9–11 days of infection the elongated cells had collapsed forming a visible brownish plaque at the tomato stem followed by a scalariform tissue with lignified and suberized cell walls. Concomitantly, an enhanced accumulation of soluble phenolic compounds (chlorogenic acid and an unidentified hydroxycinnamic acid derivative), as well as a stimulation of peroxidases, was observed. In contrast, PAL activity was not increased. Whereas the stimulation of phenylpropanoid metabolism could also be induced by artificial wounding, the described anatomical changes were only observed during attack of Cuscuta.     

Characterization of antioxidant systems, oxidation status and lipids in brain of wild-caught size-class distributed Aristeus antennatus (Risso, 1816) Crustacea, Decapoda

The objectives of the study were to characterize the enzymic antioxidant system (free radical scavenging enzymes such as catalase, superoxide dismutase, glutathione peroxidases, glutathione transferase and glutathione reductase), dietary antioxidants (vitamin E), the oxidation status (malondialdehyde (MDA) levels and the fluorescence intensity of lipid-soluble fluorescent products (LSFP)) and lipid composition (lipid classes and polyunsaturated fatty acids (PUFA) as pro-oxidants) in neural tissues from males and females of wild-caught size-class distributed blue and red marine shrimp Aristeus antennatus (Risso, 1816), trawled off the south coast of Spain. Moreover, the mechanisms that may result in the deposition of age-pigments in relation to the physiological age of this species in its natural environment were investigated. Three different size classes were defined for males and four for females, and differences were observed for the different variables measured between sexes. The proportion of polar lipids (primarily phosphatidylcholine, phosphatidylethanolamine and phosphatidylserine) predominated over that of neutral lipids, increasing significantly in males but decreasing in females. However, cerebrosides increased significantly from size–age class I to III in males but no significant differences were observed in females. The fatty acid composition showed increases in monounsaturated fatty acids (particularly 18:1 and 24:1 isomers) and dimethyl acetals, but decreases in PUFA (primarily 22:6(n-3)) with increasing size–age in both sexes. The concentration of MDA (nmol g⁻¹ brain) did not present any marked trend with size–age in both sexes. In contrast, fluorescence intensity showed increasing trends in both sexes with increasing size–age, when expressed as % fluorescence brain⁻¹ (λ_ex/em 350–445 nm and λ_ex/em 400–455). However, when expressed as % fluorescence mg⁻¹ brain total lipid, only males presented an upward trend with size–age (λ_ex/em 400–455). The concentration of vitamin E (ng mg⁻¹ brain) did not show significant differences between different size–age classes within the same sex and showed a molar ratio of one molecule of vitamin E per approximately 200 molecules of PUFA in brain membranes. The antioxidant enzyme activities showed clearer patterns with increasing size–age in males than in females, with catalase and glutathione transferase presenting downward trends and superoxide dismutase and total glutathione peroxidase showing upward trends. The fluorescence analysis of brain LSFP was not a useful tool to separate the population into different size–age classes, although the different patterns encountered between sexes for the variables measured points to males as better subjects for this type of study.     

Growth stimulation produced by methylene blue treatment in sweet potato

Methylene blue as an alternative treatment to gamma rays to stimulate growth in sweet potato tissue cultures, was applied in two different ways: – pre-incubation of nodal explants with methylene blue for 1 h using urea as a permeabilizer; – methylene blue directly incorporated into the culture medium. Both treatments stimulated growth, but the better performance being obtained with the second treatment, which had no toxic effect. The activity and electrophoresis pattern of peroxidase after treatment ofIpomoea batatas plantlets with methylene blue or gamma rays did not show similar results for the two treatments. Peroxidase activity was greater in leaves of gamma ray treated plants compared to the non-treated control. The results obtained with the Methylene blue treatment did not significantly change the peroxidase activity relative to the control. This revised version was published online in June 2006 with corrections to the Cover Date.