The effects of support deprivation and stimulation of the foot support zones on the lateral stiffness and electromyogram of the resting calf muscles

The lateral stiffness and electromyogram characteristics of the resting calf flexor and extensor muscles have been studied in 18 subjects during a seven-day immersion with and without mechanical stimulation of the foot support zones. It has been shown that as early as day 1 of support deprivation, the lateral stiffness steadily decreases in the m. soleus and, in contrast, drastically increases in the m. tibialis anterior. A mechanical stimulation of the foot support zones decreases the rate and degree of the changes observed in both muscles. The tight correlation of the changes in the lateral stiffness with the muscle activity suggests a significant dependence of these changes on the electromyogram characteristics at rest.     

Studies of complex lipids. Synthesis of ionophore derivatives of diphosphatidylglycerol (cardiolipin)

Synthesis of cardiolipin analogues containing an ionophore residue in the fatty acid moiety is described. The ionophore, dibenzo-18-crown-6, has been incorporated into second position of the glycerol residue by acylating mono- and dilysocardiolipin with a modified fatty acid anhydride. Lyso-derivatives of cardiolipin have been prepared by enzymatic hydrolysis of beef heart cardiolipin by snake venom phospholipase A2 (Naja naja oxiana).     

Gamma-irradiation induces in HeLa cells radioresistant DNA synthesis

Cells of a suspension HeLa culture at the logarithmic phase of growth were exposed to 60Co-gamma-rays (5 Gy), incubated in the nutritious medium, and in 4 h subjected to repeated irradiation: the dose-response function and the dynamics of DNA synthesis inhibition were determined. It was shown that DNA synthesis was inhibited to a lesser extent after preirradiation, in other words, DNA synthesis was radioresistant. A correlation between this synthesis and reproductive cell death is discussed.     

Interrelation between structure and protective action of normal and pathological ceruloplasmins during copper-induced lysis of red blood cells

The origin of the difference between the protective action of ceruloplasmin (CP) from healthy donors blood and of ceruloplasmin-like protein (p-CP) from blood of patients with Wilson disease which they exert during copper-induced lysis of red blood cells (RBC) was elucidated. The difference is due to a significant change in the carbohydrate moiety of p-CP the major proportion of which (65%) does not contain mannose and acetylglucosamine residues. The data of chromatography on lentil lectin reveal that only 4% of p-CP molecules contain the fragment [table: see text] required for binding to RBC receptors. It was shown that the time-courses of copper accumulation in RBC of normal donors and in RBC of patients with Wilson disease (p-RBC) during copper-induced lysis differ markedly from each other. The p-CP is able to prevent copper accumulation in RBC and p-RBC to a significantly less degree than CP. It was also established that CP prevents the decrease of reduced glutathione (GSH) level in RBC to a greater extent than p-CP. In contrast to CP, the p-CP exerts no effect on the decrease in GSH concentration in p-RBC. These results may indicate that no interaction between Cu2+ and reduced glutathione takes place in p-RBC, in contrast to the situation occurring in normal RBC.     

Acclimation or stress symptom? An integrated study of intraspecific variation in the clonal plant Aechmea bromeliifolia,a widespread CAM tank‐bromeliad

The clonal tank-bromeliad Aechmea bromeliifolia (Rudge) Baker was found in four different habitats in a restinga (vegetation mosaic on sandy coastal plains), of south-eastern Brazil. These habitats (swamp forest, dry forest, dry shrubland and herbaceous marsh) lie within a few hundred metres of each other along a gradient extending inland from the coast, and differ markedly in terms of light and flood regime. We compared ramet morphology, leaf anatomy and physiology, and population parameters to examine the amplitude of trait variation of this widespread species in the studied restinga. This integrated approach allowed us to examine which variation conferred acclimation and which was merely a stress symptom. A . bromeliifolia showed site-specific differences in abundance, distribution, rosette size and shape, leaf anatomical arrangement and photochemical efficiency (potential quantum yield; F _v/ F _m) during the day. Most of the variation found seemed to be related to the interaction of light and flooding. The lowest number and size of ramets at the exposed, dry shrubland was matched by a marked leaf photoinhibition, which suggested poor acclimation to local levels of light intensity and limited water supply. In the other habitats, the morpho-physiological parameters measured suggested adequate foraging behaviour and site acclimation.  © 2002 The Linnean Society of London, Botanical Journal of the Linnean Society, 2002, 140 , 391-401.