From mature needles of white spruce, Picea glauca (Moench) Voss we isolated thylakoids capable of high rates of oxygen evolution. Oxygen-evolving activity of spruce thylakoids was labile in the absence of osmoticum and declined by 40 % during 1 h on ice, compared to a 9 % dechne observed in spinách thylakoids. We compared the relative activity in spruce and spinách of the oxygen evolving complex (OEC) and the reaction centre in Triton X-100 fractionated membranes prepared and stored for 20 or 240 h at 0 or -80 °C in media with different combinations of sucrose (0.3, 0.5 and 1.0 M) and two pH values (6.0 and 7.6). In membranes detergent- fractionated and stored at pH 7.6, photosystem 2 (PS2) activity (H2O -> DCIP) was sensitive to sucrose concentration of the medium. Spruce and spinách membranes prepared and stored in 0.3 M sucrose and pH 7.6, showed 22 and 48 % activity of their respective control membranes, freshly prepared in 1 M sucrose at pH 6.0. In contrast, in membranes prepared and stored at pH 6.0, PS2 activity was less sensitive to sucrose concentration: spruce and spinách membranes in 0.3 M sucrose showed 73 and 88 % (respectively) of the activity of membranes freshly prepared in 1 M sucrose. In both species, the degree of stimulation of DCIP photoreduction by diphenylcarbazide suggested minimal damage to the reaction centre (RC) except during preparation in 0.3 M sucrose, pH 7.6. Since the spruce RCs were not more labile than those of spinách, the extra sensitivity of spruce thylakoids in media of low sucrose concentration was likely due to extra lability of the OEC.
Inactivation of photosynthesis during atmospheric and osmotic (highly concentrated NaCl or sucrose solutions) dehydration was monitored by measurement of chlorophyll fluorescence induction (OIP-phase, Kautsky-curves) in three lichen species. The induction curves were changed in a very similar way by all three treatments. All dehydration effects were rapidly reversible after rehydration. At relatively mild water stress, the rise time to the transient peak Fp was prolonged, and the variable part of fluorescence was diminished. In addition, at severe water stress, a considerable decline of the F0 value was observed. For NaCl treatment this effect started at water potentials <-8.5 MPa in P. aphthosa, <-12 MPa in H. physodes, and <-21 MPa in L. pulmonaria. Above these water potentials, our observations are in agreement with values from desiccation-tolerant algae, higher plants, and lichens, where an inactivation on the photosystem 2 (PS2) donor side has been postulated. At very low water potentials, the decrease in F0 probably monitors changes in the organization of the antenna apparatus of PS2. and M. Jensen, Samira Chakir, G. B. Feige.
Metabolic syndrome is a prevalent disease resulting from an interplay of genomic component and the exposome. Parental diet has been shown to affect offspring metabolic health via multiple epigenetic mechanisms. Excess carbohydrate intake is one of the driving forces of the obesity and metabolic syndrome pandemics. This review summarizes the evidence for the effects of maternal carbohydrate (fructose, sucrose, glucose) overnutrition on the modulation of metabolic syndrome components in the offspring. Despite substantial discrepancies in experimental design, common effects of maternal carbohydrate overnutrition include increased body weight and hepatic lipid content of the "programmed" offspring. However, the administration of sucrose to several rat models leads to apparently favorable metabolic outcomes. Moreover, there is evidence for the role of genomic background in modulating the metabolic programming effect in the form of nutri-epigenomic interaction. Comprehensive, robust studies are needed to resolve the temporal, sex-specific, genetic, epigenetic and nutritional aspects of parental overnutrition in the intergenerational and transgenerational pathogenesis of metabolic syndrome.
An attempt was made to assess whether the choice of the gradient media could influence the yield of basolateral membrane vesicles isolated from the rat intestine as well as their functional characteristics. Crude membranes prepared in the same way were therefore centrifuged with 10 % Percoll, on a discontinuous sucrose gradient or on a continuous sorbitol gradient. The protein yield was significantly higher with the Percoll gradient than with sucrose and sorbitol gradient centrifugation (2.7 ±1.0 %; 0.4 ±0.1 %; 0.6±0.2 %, respectively). Enrichment in Ma+,K+-ATPase was similar in all three preparations (8.50±2.34; 8.22±4.78; 8.20±2.08). However, contamination with brush border membranes was significantly higher after Percoll gradient centrifugation and negligible after the use of the other two gradient media. Transport of D-glucose in the BLM prepared by Percoll gradient centrifugation also indicated some contamination with functional brush-border membranes. An attempt to purify basolateral membrane vesicles after Percoll gradient centrifugation with Ca2+ precipitation, however, reduced the protein yield to less than 1 %. We conclude that in the preparation of basolateral membrane vesicles from the rat enterocytes each of the gradient media may have certain advantages and disadvantages, which should be considered according to the purpose of the preparation.
The effect of 3 months feeding with diets of different protein and sucrose content (9 % casein -f 70 % sucrose vs. 18 % casein + 61 % sucrose) on the development of diabetic nephropathy and changes in serum lipid spectrum was investigated in rats with insulin-dependent diabetes (streptozotocin 45 mg.kg-1). Metabolism of diabetic animals (before the nutritional regimen) was characterized by hyperglycaemia, moderate hyperlipidaemia, lipid accumulation in the liver and elevated creatinine concentration in the blood. Kidney weight and protein content were not significantly changed. Histological picture of kidneys showed initial changes of glomerular structure. After three months hyperlipoproteinaemia was more accentuated in animals given either of the two diets, the kidneys were hypertrophic with a higher protein content and displayed morphological changes of diabetic nephropathy. Animals given the low-protein diet developed smaller morphological changes both in glomeruli and tubuli. The study indicates that dietary protein and not hyperlipoproteinaemia is the major factor, which may significantly influence the progress of diabetic nephropathy.
Among four mulberry (Morus alba L.) cultivars (K-2, MR-2, BC2-59, and S-13), highest net photosynthetic rate (PN) was observed in BC2-59 while the lowest rates were recorded with K-2. Significant differences among the four cultivars were found in leaf area, biomass production, activities of ribulose-1,5-bisphosphate carboxylase and sucrose phosphate synthase, and glucose and sucrose contents. The PN and the activities of photosynthetic enzymes in the four cultivars were significantly correlated with the growth and biomass production measured as leaf yield, total shoot mass, and aerial plant biomass. and K. V. Chaitanya ... [et al.].