Accumulation of phenolics and growth rate of barley seedlings (Hordeum vulgare L.)

Accumulation of phenolics in barley seedlings was examined in relation to elongation; the seedlings were cultivated at 5 °C or 26 °C in light or in darkness. It was found that a higher accumulation of phenolics (mainly saponarin) was accompanied by slower elongation. This relation was repeatedly observed regardless of whether growth retardation or stimulation was obtained by light and temperature conditions of growth or treatment with CCO orp-fluorophenylalanine (p-FPA), respectively. It is proposed that PAL and peroxidase activities are responsible for maintaining the level of phenolics in seedlings. These enzyme activities are differently influenced by temperature conditions of growth. It is also suggested that accumulation of saponarin may lead to slowing down the growth by stimulating IAA oxidase and lowering the auxin level in the tissues. Thus, phenolics may belong to the factors through which environmental conditions influence elongation of seedlings.     

Cloning of cysB mutant alleles of S. typhimurium

Two cysB mutant alleles of S. typhimurium have been cloned onto pBR vectors. The product of the constitutive cysBc 1352 allele present on the plasmid was found to fulfill regulatory functions: as an activator of the cysteine regulon and as an autorepressor. CysB70 auxotrophic mutation impairs both regulatory functions cysB protein. Transfer of the clones cysBc 1352 allele from E. coli to S. typhimurium and from S. typhimurium to E. coli and biochemical analysis of transformants suggest involvement of a restriction-modification system in the constitutive expression of the cysteine regulon.     

Plasma free amino acid profiling as metabolomic diagnostic and prognostic biomarker in paediatric cancer patients: a follow-up study

Amino acids (AAs) play a crucial role in cancer cell metabolism. Levels of 22 plasma AAs at the time of diagnosis and after treatment were established among 39 pediatric cancer patients and 33 healthy children. Glutamic acid levels decreased and tryptophan levels increased during treatment. Cancer patients presented significantly lower levels of glutamine and leucine post-treatment while levels of 12 other AAs were higher comparing to controls. Results suggest that plasma free AA profile may serve as a prognostic biomarker.

     

Visible light inactivation of bacteria and fungi by modified titanium dioxide.

Visible light induced photocatalytic inactivation of bacteria (Escherichia coli, Staphylococcus aureus, Enterococcus faecalis) and fungi (Candida albicans, Aspergillus niger) was tested. Carbon-doped titanium dioxide and TiO2 modified with platinum(IV) chloride complexes were used as suspension or immobilised at the surface of plastic plates. A biocidal effect was observed under visible light irradiation in the case of E. coli in the presence of both photocatalysts. The platinum(IV) modified titania exhibited a higher inactivation effect, also in the absence of light. The mechanism of visible light induced photoinactivation is briefly discussed. The observed detrimental effect of photocatalysts on various microorganism groups decreases in the order: E. coli > S. aureus approximately E. faecalis>C. albicans approximately A. niger. This sequence results most probably from differences in cell wall or cell membrane structures in these microorganisms and is not related to the ability of catalase production.     

Regulation of renal Na(+),K(+)-ATPase and ouabain-sensitive H(+),K(+)-ATPase by the cyclic AMP-protein kinase A signal transduction pathway

We investigated the effect of the cyclic AMP-protein kinase A (PKA) signalling pathway on renal Na(+),K(+)-ATPase and ouabain-sensitive H(+),K(+)-ATPase. Male Wistar rats were anaesthetized and catheter was inserted through the femoral artery into the abdominal aorta proximally to the renal arteries for infusion of the investigated substances. Na(+),K(+)-ATPase activity was measured in the presence of Sch 28080 to block ouabain-sensitive H(+),K(+)-ATPase and improve specificity of the assay. Dibutyryl-cyclic AMP (db-cAMP) administered at a dose of 10(-7) mol/kg per min and 10(-6) mol/kg per min increased Na(+),K(+)-ATPase activity in the renal cortex by 34% and 42%, respectively, and decreased it in the renal medulla by 30% and 44%, respectively. db-cAMP infused at 10(-6) mol/kg per min increased the activity of cortical ouabain-sensitive H(+),K(+)-ATPase by 33%, and medullary ouabain-sensitive H(+),K(+)-ATPase by 30%. All the effects of db-cAMP were abolished by a specific inhibitor of protein kinase A, KT 5720. The stimulatory effect on ouabain-sensitive H(+),K(+)-ATPase and on cortical Na(+),K(+)-ATPase was also abolished by brefeldin A which inhibits the insertion of proteins into the plasma membranes, whereas the inhibitory effect on medullary Na(+),K(+)-ATPase was partially attenuated by 17-octadecynoic acid, an inhibitor of cytochrome p450-dependent arachidonate metabolism. We conclude that the cAMP-PKA pathway stimulates Na(+),K(+)-ATPase in the renal cortex as well as ouabain-sensitive H(+),K(+)-ATPase in the cortex and medulla by a mechanism requiring insertion of proteins into the plasma membrane. In contrast, medullary Na(+),K(+)-ATPase is inhibited by cAMP through a mechanism involving cytochrome p450-dependent arachidonate metabolites.     

Bidirectional regulation of renal cortical Na+,K+-ATPase by protein kinase C

We examined the role of protein kinase C (PKC) in the regulation of Na+,K+- ATPase activity in the renal cortex. Male Wistar rats were anaesthetized and the investigated reagents were infused into the abdominal aorta proximally to the renal arteries. A PKC-activating phorbol ester, phorbol 12,13-dibutyrate (PDBu), had a dose-dependent effect on cortical Na+,K+-ATPase activity. Low dose of PDBu (10(-11) mol/kg per min) increased cortical Na+,K+-ATPase activity by 34.2%, whereas high doses (10(-9) and 10(-8) mol/kg per min) reduced this activity by 22.7% and 35.0%, respectively. PDBu administration caused changes in Na+,K+-ATPase Vmax without affecting K(0.5) for Na+, K+ and ATP as well as Ki for ouabain. The effects of PDBu were abolished by PKC inhibitors, staurosporine, GF109203X, and G? 6976. The inhibitory effect of PDBu was reversed by pretreatment with inhibitors of cytochrome P450-dependent arachidonate metabolism, ethoxyresorufin and 17-octadecynoic acid, inhibitors of phosphatidylinositol 3-kinase (PI3K), wortmannin and LY294002, and by actin depolymerizing agents, cytochalasin D and latrunculin B. These results suggest that PKC may either stimulate or inhibit renal cortical Na+,K+-ATPase. The inhibitory effect is mediated by cytochrome P450-dependent arachidonate metabolites and PI3K, and is caused by redistribution of the sodium pump from the plasma membrane to the inactive intracellular pool.     

Evidence for the Cost of Reproduction in Humans: High Lifetime Reproductive Effort Is Associated with Greater Oxidative Stress in Post-Menopausal Women

Life history theory predicts trade-offs between reproductive effort and maternal survivorship in energy-restricted environments. However, empirical evidence for the positive association between maternal mortality and reproductive effort from energetically challenged human populations are mixed and physiological mechanisms that may underlie this association are poorly understood. We hypothesized that increases in aerobic metabolism during repeated periods of pregnancy and lactation result in increased oxidative stress that may contribute to somatic deterioration, vulnerability to illness, and accelerated aging. We therefore predicted that lifetime gravidity and parity would be related to levels of biomarkers of oxidative stress, as well as antioxidative defence enzymes in post-menopausal women. Our hypothesis was supported by positive linear associations between levels of 8-OHdG, a biomarker of DNA oxidative damage (β = 0.21, p<0.05), levels of antioxidative defence enzyme Cu-Zn SOD (β = 0.25, p<0.05), and number of lifetime pregnancies. Furthermore, independent of age and health status, post-menopausal women with higher gravidity and parity (> = 4 pregnancies per lifetime) had 20% higher levels of 8-OHdG and 60% higher levels of Cu-Zn SOD compared to women with lower gravidity and parity (<4 pregnancies per lifetime). Our results present the first evidence for oxidative stress as a possible cost of reproductive effort in humans.     

Daily and circadian rhythms in the activity of mixed function oxidases system in rats of different age

Abstract

An age‐associated alterations in daily and circadian changes of cytochrome P‐450‐linked monooxygenases system activity were studied using 1‐, 6‐ and 12‐months old male Wistar rats, in winter and in spring season. Cytochrome P‐450 and NADPH‐cytochrome P‐450 reductase showed 12h rhythm in all investigated age groups of animals. Cytochrome b₅ and NADH‐cytochrome b₅ reductase were characterized by a 12h daily rhythm in 1‐month old rats, but in older ones 24h circadian rhythm was found. There was not significant changes of the rhythm pattern in the activity of investigated MFO system ingredients in rats of different age, between spring and winter.     

Regulation of the skeletal sarcoplasmic reticulum Ca2+-ATPase by phospholamban and negatively charged phospholipids in reconstituted phospholipid vesicles

The Ca²⁺-ATPase of skeletal sarcoplasmic reticulum was purified and reconstituted in proteoliposomes containing phosphatidylcholine (PC). When reconstitution occurred in the presence of PC and the acidic phospholipids, phosphatidylserine (PS) or phosphatidylinositol phosphate (PIP), the Ca²⁺-uptake and Ca²⁺-ATPase activities were significantly increased (2–3 fold). The highest activation was obtained at a 50:50 molar ratio of PSYC and at a 10:90 molar ratio of PIP:PC. The skeletal SR Ca²⁺-ATPase, reconstituted into either PC or PC:PS proteoliposomes, was also found to be regulated by exogenous phospholamban (PLB), which is a regulatory protein specific for cardiac, slow-twitch skeletal, and smooth muscles. Inclusion of PLB into the proteoliposomes was associated with significant inhibition of the initial rates of Ca²⁺-uptake, while phosphorylation of PLB by the catalytic subunit of cAMP-dependent protein kinase reversed the inhibitory effects. The effects of PLB on the reconstituted Ca²⁺-ATPase were similar in either PC or PC: PS proteoliposomes, indicating that inclusion of negatively charged phospholipid may not affect the interaction of PLB with the skeletal SR Ca²⁺-ATPase. Regulation of the Ca²⁺-ATPase appeared to involve binding with the hydrophilic portion of phospholamban, as evidenced by crosslinking experiments, using a synthetic peptide which corresponded to amino acids 1–25 of phospholamban. These findings suggest that the fast-twitch isoform of the SR Ca²⁺-ATPase may be also regulated by phospholamban although this regulator is not expressed in fast-twitch skeletal muscles.     

The first phospholipase inhibitor from the serum of Vipera ammodytes ammodytes

Ammodytoxins are neurotoxic secretory phospholipase A(2) molecules, some of the most toxic components of the long-nosed viper (Vipera ammodytes ammodytes) venom. Envenomation by this and by closely related vipers is quite frequent in southern parts of Europe and serotherapy is used in the most severe cases. Because of occasional complications, alternative medical treatment of envenomation is needed. In the present study, ammodytoxin inhibitor was purified from the serum of V. a. ammodytes using two affinity procedures and a gel exclusion chromatography step. The ammodytoxin inhibitor from V. a. ammodytes serum consists of 23- and 25-kDa glycoproteins that form an oligomer, probably a tetramer, of about 100 kDa. N-terminal sequencing and immunological analysis revealed that both types of subunit are very similar to gamma-type secretory phospholipase A(2) inhibitors. The ammodytoxin inhibitor from V. a. ammodytes serum is a potent inhibitor of phospholipase activity and hence probably also the neurotoxicity of ammodytoxins. Discovery of the novel natural inhibitor of these potent secretory phospholipase A(2) toxins opens up prospects for the development of new types of small peptide inhibitors for use in regulating the physiological and pathological activities of secretory phospholipases A(2).