Substrate-dependent modulation of ATPase activity by Na+ and K+ in roots of Plantago species

The equal rates of water vapour absorption by both bi- and trinucleate pollen indicate that their widely-differing rates of respiration have an intrinsic, biochemical basis. This was investigated with various metabolic inhibitors that were previously introduced into dry pollen via anhydrous acetone. The uncoupler, carbonyl cyanide m-chlorophenyl hydrazone, inhibited the O₂ uptake of rapidly respiring pollen and stimulated that of slowly respiring types to similar absolute values, that probably reflect the rates of substrate transport across the mitochondrial membranes. The extent of inhibition of the O₂ uptake by oligomycin, dicyclohexyl carbodiimide, antimycin A, and salicyl hydroxamic acid, alone and in combinations, indicates that hardly any oxidative phosphorylation and anabolic activities occur in slowly respiring, binucleate pollen species, having low-developed mitochondria and high energy charge values. The presence of the alternative pathway was insignificant. In other binucleate pollen species, characterized by recognizable mitochondria and low energy charge values, a limited ATP synthesis was established. The low energy charge values point to imbalance between phosphorylative and anabolic activities. In rapidly respiring, trinucleate pollen, containing well-developed mitochondria, a significant activity of the alternative oxidase was found. The energy charge values were high notwithstanding the large demand for ATP, mounting to 1.7 μmol h^?1 (mg pollen)^?1. In some pollen species, oligomycin highly stimulated the flow of electrons through the cytochrome pathway, which made an estimation of the ATP synthesis impossible.     

Effects of lifestyle and genetic polymorphisms on consumption of coffee or black tea and urinary caffeine levels

To find the cause of individual differences in caffeine intake and its metabolism, we investigated the effects of lifestyle and genetic polymorphisms of caffeine metabolic enzymes on coffee or black tea and urinary caffeine levels among 259 male Japanese. It was seen that cigarette smokers drank more coffee or black tea than non-smokers (p < 0.001). There was an inverse correlation between the amount of coffee or black tea consumed and age or the frequency of alcohol drinking (p < 0.05). Genetic polymorphisms of N -acetyltransferase 2 (NAT2), cytochrome P450 (CYP)1A1 and 2E1 did not significantly affect the habit of drinking coffee or black tea. The frequency of allele 1, the NAT2 allele of rapid acetylators, increased according to coffee or black tea consumption (0.05 < p < 0.1). Among lifestyle factors, two factors, i.e. smoking and the amount of coffee or black tea consumed, were related to urinary caffeine levels (p < 0.05). Geometric means of urinary caffeine levels were higher in the group who consumed higher amounts of coffee or black tea (p < 0.05) and those of smokers were lower than non-smokers- approximately 70% of non-smokers (p < 0.05). The genetic polymorphisms of NAT2, CYP1A1 and CYP2E1 were not significantly associated with the urinary caffeine levels according to each consumption level of coffee or black tea. This study suggests that smoking should be considered for the proper appreciation of individual differences in caffeine intake and urinary caffeine levels.     

Modeling dynamics of stable carbon isotopic exchange between a boreal forest ecosystem and the atmosphere

Stable isotopes of CO₂ contain unique information on the biological and physical processes that exchange CO₂ between terrestrial ecosystems and the atmosphere. In this study, we developed an integrated modeling system to simulate dynamics of stable carbon isotope of CO₂, as well as moisture, energy, and momentum, between a boreal forest ecosystem and the atmosphere, as well as their transport/mixing processes through the convective boundary layer (CBL), using remotely sensed surface parameters to characterize the surface heterogeneity. It has the following characteristics: (i) it accounts for the influences of the CBL turbulent mixing and entrainment of the air aloft; (ii) it scales individual leaf‐level photosynthetic discrimination up to the whole canopy (Δ_canopy) through the separation of sunlit and shaded leaf groups; (iii) it has the capacity to examine the detailed interrelationships among plant water‐use efficiency, isotope discrimination, and vapor pressure deficit; and (iv) it has the potential to investigate how an ecosystem discriminates against ¹³C at various time and spatial scales. The monthly mean isotopic signatures of ecosystem respiration (i.e. δ¹³C_R) used for isotope flux calculation are retrieved from the nighttime flask data from the intensive campaigns (1998–2000) at 20 m level on Fraserdale tower, and the data from the growing season in 1999 are used for model validation. Both the simulated CO₂ mixing ratio and δ¹³C of CO₂ at the 20 m level agreed with the measurements well in different phases of the growing season. On a diurnal basis, the greatest photosynthetic discrimination at canopy level (i.e. Δ_canopy) occurred early morning and late afternoon with a varying range of 10–26‰. The diurnal variability of Δ_canopy was also associated with the phases of growing season and meteorological variables. The annual mean Δ_canopy in 1999 was computed to be 19.58‰. The monthly averages of Δ_canopy varied between 18.55‰ and 20.84‰ with a seasonal peak during the middle growing season. Because of the strong opposing influences of respired and photosynthetic fluxes on forest air (both CO₂ and ¹³CO₂) on both the diurnal and seasonal time scales, CO₂ was consistently enriched with the heavier ¹³C isotope (less negative δ¹³C) from July to October and depleted during the remaining months, whereas on a diurnal basis, CO₂ was enriched with the heavier ¹³C in the late afternoon and depleted in early morning. For the year 1999, the model results reveal that the boreal ecosystem in the vicinity of Fraserdale tower was a small sink with net uptake of 29.07 g ¹²C m^?2 yr^?1 and 0.34 g ¹³C m^?2 yr^?1.     

A feasible Global Carbon Cycle Observing System: a plan to decipher today's carbon cycle based on observations

A design is presented to continuously monitor the transfers of carbon between the atmosphere and the terrestrial biosphere and oceans on large spatial scales. A consideration of the expected signal-to-noise suggests that a very cost effective method is to perform repeated measurements of the mixing ratios of trace gases in the atmospheric column at an increased number of sites compared to the present geographical coverage. This can be accomplished with existing technology, provided that more automation is applied to the sampling process as well as to the analytical procedures. The resulting data will be crucial to test extrapolations based on direct flux measurements to regional and global scales.     

COMMENTS ON SCRIVEN AND MAK

In their article Scriven and Mak (1991) claim to have used Generalized Procrustes Analysis (GPA) to analyze their data. However, the Consensus program they used does not perform a GPA. Since 1989 there is a very fast GPA program that runs on microprocessors.     

The Effect of Salinity on Growth, Cation Content, Na+-Uptake and Translocation in Salt-Sensitive and Salt-Tolerant Plantago Species

Growth of salt-sensitive Plantago media L. and salt-tolerant P. coronopus L. and P. maritima L. was followed under saline conditions. Growth was reduced according to the ecological features of these species: P. media was sensitive to 25 mM NaCl, while P, coronopus and P. maritima could grow in 150 mM and 300 mM NaCl, respectively. The three Plantago species accumulated Na⁺ in the shoot and maintained a relatively low Na⁺ level in the root. K⁺. Mg²⁺ and Ca²⁺ levels of both shoots and roots decreased with increasing salinity. The results suggest that the difference between salt-resistant and salt-sensitive species is located in the ion secretory system which is involved in the ion translocation from the root to the shoot rather than in the primary uptake process through the plasmalemma of the cortical cells.     

Lipid and Fatty Acid Composition of Tree-Growing and Terrestrial Lichens

A comparison of lipid and fatty acid composition was made of the tree-growing lichens Evernia prunastri (L.) Ach., Parmelia saxatilis (L.) Ach. and Hypogymnia physodes (L.) Ach. and the terrestrial species Cetraria islandica (L.) Ach. and Cladonia impexa Harm. In the terrestrial species the total lipid content varied strongly during spring, while the tree-growing species showed much less variation. Phospholipid and sterol content of all lichens was unusually low. Monoglycosyl diglyceride was absent from Parmelia saxatilis. Fatty acids common to higher plants as palmitic, stearic, oleic, linoleic and linolenic acid were invariably present in all lichen species. In addition large quantities of extra-long chain fatty acids like behenic acid, eicosadienoic acid and cyclic aliphatic lichen acids were present in the terrestrial species. The degree of (poly) unsaturation decreased in the order Evernia prunastri, Parmelia saxatilis. Fatty acids common to higher plants as palmitic, stearic, impexa, which decrease was compensated by an increase in extralong chain fatty acids and lichen acids. It is suggested that the lichen acids are of adaptive value for lichen species growing in the terrestrial habitats, which were characterized by extreme diurnal temperature variations. Just as the polyunsaturated fatty acids, lichen acids guarantee at lower temperatures a high flexibility of the membranes involved, at the same time as they are less susceptible to photo-oxidation at the high daytime temperatures.