Isolation and partial characterisation of acid phosphatase isozymes from dormant oilseed of<Emphasis Type="Italic"> Corylus avellana</Emphasis> L.

The acid phosphatase (orthophosphoric-monoester phosphohydrolase, EC 3.1.3.2) complement from dormant hazel (Corylus avellana L.) seeds was found to exhibit significant electrophoretic heterogeneity partially attributable to the presence of distinct molecular forms. In axiferous tissue, total acid phosphatase activity increased in a biphasic fashion during chilling, a treatment necessary to alleviate seed dormancy. Three acid phosphatase isozymes were isolated from cotyledons of dormant hazel seeds by successive ammonium sulphate precipitation, size-exclusion, Concanavalin A affinity, cation- and anion-exchange chromatographies resulting in 75-, 389- and 191-fold purification (APase1, APase2, APase3, respectively). The three glycosylated isoforms were isolated to catalytic homogeneity as determined by electrophoretic, kinetic and heat-inactivation studies. The native acid phosphatase complement of hazel seeds had an apparent M_r of 81.5±3.5 kDa as estimated by size-exclusion chromatography, while the determined pI values were 5.1 (APase1), 6.9 (APase2) and 7.3 (APase3). The optimum pH for p-nitrophenyl phosphate hydrolysis was pH 3 (APase1), pH 5.6 (APase2) and pH 6 (APase3). The hazel isozymes hydrolysed a variety of phosphorylated substrates in a non-specific manner, exhibiting low K_m and the highest specificity constant (V_max/K_m) for pyrophosphate. They were not primary phytases since they could not initiate phytic acid hydrolysis, while APase2 and APase3 had significant phospho-tyrosine phosphatase activity. Inorganic phosphate was a competitive inhibitor, while activity was significantly impaired in the presence of vanadate and fluoride.Abbreviations APase Acid phosphatase (EC 3.1.3.2) - ConA Concanavalin A–Sepharose 4B - CV Column volume - -GP -Glycerophosphate - IEF Isoelectric focusing - IP6 Phytic acid - pNPP p-Nitrophenyl phosphate - PAGE Polyacrylamide gel electrophoresis - PPi Pyrophosphate     

Nano-tubular cellulose for bioprocess technology development

Delignified cellulosic material has shown a significant promotional effect on the alcoholic fermentation as yeast immobilization support. However, its potential for further biotechnological development is unexploited. This study reports the characterization of this tubular/porous cellulosic material, which was done by SEM, porosimetry and X-ray powder diffractometry. The results showed that the structure of nano-tubular cellulose (NC) justifies its suitability for use in "cold pasteurization" processes and its promoting activity in bioprocessing (fermentation). The last was explained by a glucose pump theory. Also, it was demonstrated that crystallization of viscous invert sugar solutions during freeze drying could not be otherwise achieved unless NC was present. This effect as well as the feasibility of extremely low temperature fermentation are due to reduction of the activation energy, and have facilitated the development of technologies such as wine fermentations at home scale (in a domestic refrigerator). Moreover, NC may lead to new perspectives in research such as the development of new composites, templates for cylindrical nano-particles, etc.     

Assessing the effects of land-use change on plant traits, communities and ecosystem functioning in grasslands: a standardized methodology and lessons from an application to 11 European sites

BACKGROUND AND AIMS: A standardized methodology to assess the impacts of land-use changes on vegetation and ecosystem functioning is presented. It assumes that species traits are central to these impacts, and is designed to be applicable in different historical, climatic contexts and local settings. Preliminary results are presented to show its applicability. METHODS: Eleven sites, representative of various types of land-use changes occurring in marginal agro-ecosystems across Europe and Israel, were selected. Climatic data were obtained at the site level; soil data, disturbance and nutrition indices were described at the plot level within sites. Sixteen traits describing plant stature, leaf characteristics and reproductive phase were recorded on the most abundant species of each treatment. These data were combined with species abundance to calculate trait values weighed by the abundance of species in the communities. The ecosystem properties selected were components of above-ground net primary productivity and decomposition of litter. KEY RESULTS: The wide variety of land-use systems that characterize marginal landscapes across Europe was reflected by the different disturbance indices, and were also reflected in soil and/or nutrient availability gradients. The trait toolkit allowed us to describe adequately the functional response of vegetation to land-use changes, but we suggest that some traits (vegetative plant height, stem dry matter content) should be omitted in studies involving mainly herbaceous species. Using the example of the relationship between leaf dry matter content and above-ground dead material, we demonstrate how the data collected may be used to analyse direct effects of climate and land use on ecosystem properties vs. indirect effects via changes in plant traits. CONCLUSIONS: This work shows the applicability of a set of protocols that can be widely applied to assess the impacts of global change drivers on species, communities and ecosystems.     

An evolutionary perspective on leaf economics: phylogenetics of leaf mass per area in vascular plants

In plant leaves, resource use follows a trade‐off between rapid resource capture and conservative storage. This “worldwide leaf economics spectrum” consists of a suite of intercorrelated leaf traits, among which leaf mass per area, LMA, is one of the most fundamental as it indicates the cost of leaf construction and light‐interception borne by plants. We conducted a broad‐scale analysis of the evolutionary history of LMA across a large dataset of 5401 vascular plant species. The phylogenetic signal in LMA displayed low but significant conservatism, that is, leaf economics tended to be more similar among close relatives than expected by chance alone. Models of trait evolution indicated that LMA evolved under weak stabilizing selection. Moreover, results suggest that different optimal phenotypes evolved among large clades within which extremes tended to be selected against. Conservatism in LMA was strongly related to growth form, as were selection intensity and phenotypic evolutionary rates: woody plants showed higher conservatism in relation to stronger stabilizing selection and lower evolutionary rates compared to herbaceous taxa. The evolutionary history of LMA thus paints different evolutionary trajectories of vascular plant species across clades, revealing the coordination of leaf trait evolution with growth forms in response to varying selection regimes.     

White coat hypertension and haemostatic/fibrinolytic balance disorders

White coat hypertension (WCH) or isolated clinic hypertension is generally accepted to be a benign condition, although some reports have suggested that it may be associated with an increased cardiovascular event rate or other cardiovascular alterations. It has been previously shown that essential hypertension (EH) is associated with abnormalities in haemostatic/fibrinolytic balance and endothelial function. The aim of our study was to assess the impact of WCH on fibrinolytic balance and endothelial function by measuring plasma levels of plasminogen activator inhibitor-1 (PAI-1), tissue plasminogen activator antigen (tPA), fibrinogen, and thrombomodulin. These markers were determined in 71 patients with EH, 26 with WCH and 87 normotensive healthy control subjects. The three groups were not different with respect to age, gender, smoking habits, BMI and blood lipids. Subjects with WCH were found to have increased plasma levels of PAI-1, tPA, fibrinogen and thrombomodulin compared to controls, but less compared to hypertensive ones. Our results suggest that WCH may be associated with decreased fibrinolytic potential and endothelial dysfunction, indicating that WCH may not be a completely harmless trait.     

Impact of obesity in intima media thickness of carotid arteries

Objective: To explore differences in intima media thickness (IMT) of the carotid arteries induced by differences in BMI. Research Methods and Procedures: Data from 3173 consecutive subjects, who were referred to our Hypertension Center from 1998 to 2004, were reviewed. Criteria for patients to be considered for further analysis included no past or concurrent antihypertensive medication, no concurrent medication with the potential to raise blood pressure (BP) (e.g., prednisone), and no clinical signs or laboratory evidence of secondary causes of hypertension. Our population was divided into four groups according to NIH criteria for obesity: underweight, normal weight, overweight, and obese. BMI, mean IMT of internal carotid arteries, and 24‐hour BP values were available for all subjects. Five hundred thirty six subjects of the four groups, matched for age, gender, and mean 24‐hour BP values, were included in the analysis. Results: Mean IMT of internal carotid arteries was increased with increasing BMI. Mean IMT was significantly higher in obese subjects compared with normal‐weight (p < 0.01) and underweight (p < 0.001) subjects. Mean IMT was significantly higher in overweight subjects compared with normal‐weight ones (p < 0.05). Furthermore, multivariate regression analysis in obese subjects revealed that fasting serum glucose was independently associated with IMT. Discussion: Obesity may be an important factor for carotid atherosclerosis, and at least some of the effects of obesity are independent of the BP levels. Fasting serum glucose levels in obese subjects may play an important role in carotid atherosclerosis.     

Inspiratory muscle adaptations following pressure or flow training in humans

Skeletal muscle adapts differently to training with high forces or with high velocities. The effects of these disparate training protocols on the inspiratory muscles were investigated in ten healthy volunteers. Five subjects trained using high force (pressure) loads (pressure trainers) and five trained using high velocity (flow) loads (flow trainers). Pressure training entailed performing 30 maximal static inspiratory efforts against a closed airway. Flow training entailed performing 30 sets of three maximal dynamic inspiratory efforts against a minimal resistance. Training was supervised and carried out 5 days a week for 6 weeks. Inspiratory flow rates and oesophageal pressure-time curves were measured before and after training. Peak inspiratory pressures during maximal static and dynamic efforts and peak flows during the maximal dynamic efforts were calculated. The time-to-peak pressure and rate of rise in peak pressure during maximal static and dynamic manoeuvres were also calculated before and following training. Maximal static pressure increased in the pressure training group and maximal dynamic pressure increased in the flow training group. Both groups increased the rate of pressure production (dP/dt) during their respective maximal efforts. The post-training decrease in time-to-peak pressure was proportionately greater in the flow trainers than in the pressure trainers. The differences in time-to-peak pressure between the two groups were consistent with the different effects of force and velocity training on the time-to-peak tension of skeletal muscle.