The Chlamydomonas genome reveals the evolution of key animal and plant functions

Chlamydomonas reinhardtii is a unicellular green alga whose lineage diverged from land plants over 1 billion years ago. It is a model system for studying chloroplast-based photosynthesis, as well as the structure, assembly, and function of eukaryotic flagella (cilia), which were inherited from the common ancestor of plants and animals, but lost in land plants. We sequenced the approximately 120-megabase nuclear genome of Chlamydomonas and performed comparative phylogenomic analyses, identifying genes encoding uncharacterized proteins that are likely associated with the function and biogenesis of chloroplasts or eukaryotic flagella. Analyses of the Chlamydomonas genome advance our understanding of the ancestral eukaryotic cell, reveal previously unknown genes associated with photosynthetic and flagellar functions, and establish links between ciliopathy and the composition and function of flagella.     

Interannual and seasonal changes in the soil exchange rates of monoterpenes and other VOCs in a Mediterranean shrubland

Information about soil VOC inventories and exchange rates in different soils is very scarce. Seasonality of soil VOC exchange rates is also largely unknown, despite the increasing interest in some soil volatile compounds, such as monoterpenes, because of their important role in soil ecology. We aimed to explore and quantify soil VOC exchange rates in a Mediterranean shrubland and their seasonality. Measurements of soil VOC exchange were taken using GC‐MS and PTR‐MS techniques, together with soil temperature, soil moisture and soil CO₂ efflux measurements, during two annual campaigns with contrasting precipitation. Methanol, acetic acid, ethyl acetate, acetaldehyde, acetone, C₃ and C₄ carbonyls (such as methyl ethyl ketone), α‐pinene and limonene, showed the highest emission rates. Maximum soil monoterpene emission rates were very low (0.003 nmol m^?2 s^?1) compared with foliar monoterpene emission rates. The emission rates of the other VOCs were also low (maximum 0.8 nmol m^?2 s^?1) except for methanol (1.2 nmol m^?2 s^?1). Maximum soil uptake rates for some VOCs, such as methanol and acetonitrile (ranging from ?0.1 to ?0.5 nmol m^?2 s^?1) were, however, comparable with foliar uptake rates. Further studies are needed to corroborate these results and the possible importance of the soil VOC sink in regional chemistry‐climate models. Long‐term severe drought increased soil monoterpene emission rates in this Mediterranean shrubland. The increases seem to be linked to changes in the soil’s physical properties induced by low soil moisture. Unlike monoterpenes, other soil VOC emission rates decreased when soil moisture was low. The results suggest a seasonal control of soil temperature on the emission rates of monoterpenes and other VOCs. The emission rates increase with soil temperature. Positive correlations between the VOC exchange rates and the soil CO₂ fluxes suggest that phenology of roots and microorganisms also controls seasonal changes in soil VOCs in this Mediterranean shrubland.     

Alkylating potential of potassium sorbate

A kinetic study of the alkylating potential of potassium sorbate (S)-a food preservative used worldwide-in 7:3 water/dioxane medium was performed. The following conclusions were drawn: (i) Potassium sorbate shows alkylating activity on the nucleophile 4-(p-nitrobenzyl)pyridine (NBP), a trap for alkylating agents with nucleophilic characteristics similar to those of DNA bases, (ii) The NBP alkylation reaction complies with the rate equation r = k(alk)[H+][S][NBP]/(K(a) + [H+]), K(a) being the sorbic acid dissociation constant and k(alk) the rate constant of NBP alkylation by the undissociated acid. In the range of pH 5-6, the alkylation time ranges between 18 days (pH 5.2) and >1 month (pH > or = 6). (iii) NBP alkylation occurs through a reaction with deltaH# = 78 kJ mol(-1), which is much higher than those of NBP alkylation by stronger alkylating agents. (iv) The absorption coefficient of the sorbate-NBP adduct was determined to be epsilon = 204 M(-1) cm(-1) (lambda = 580 nm), this value being rationalized in terms of the adduct structure. (v) The results can help to establish suitable expiration times for products preserved with potassium sorbate.     

Chemical and sensorial characteristics of espresso coffee as affected by grinding and torrefacto roast

Grinding is a critical step in the preparation of espresso coffee (EC). The addition of sugar during the torrefacto roasting process could influence the degree of brittleness and grinding. The aim of this work was to study the influence of the grinding grades (coarse, fine, and very fine) in Arabica/Robusta 20:80, natural roasted (A20:R80), and Arabica/Robusta 20:80 with 50% Robusta torrefacto roasted (A20:R80 50% torrefacto) on the chemical and sensorial characteristics of EC in order to select the optimal espresso grinding grade. A higher percentage of coarse particles was found in A20:R80 ground coffee. In both ECs, the extraction of solids and soluble and aroma compounds increased inversely with particle size. Higher foam indices and extraction yields were found in A20:R80 50% torrefacto ECs probably due to the solubilization of caramelized sugar and melanoidins. It has been suggested that the range of an acceptable extraction yield could be extended to 25% in A20:R80 50% torrefacto ECs. In conclusion, the optimal grinding grade for the obtainment of an EC with A20:R80 was fine and that for A20:R80 50% torrefacto was coarse.     

Characterization of espresso coffee aroma by static headspace GC-MS and sensory flavor profile.

The aromas of three espresso coffee (EC) samples from different botanical varieties and types of roast (Arabica coffee, Robusta natural blend, and Robusta Torrefacto blend (special roast by adding sugar)) were studied by static headspace GC-MS and sensory flavor profile analysis. Seventy-seven compounds were identified in all of the EC samples. Among them, 13 key odorants have been quantified and correlated with their flavor notes by applying multivariate statistical methods. Some correlations have been found in the EC samples: some aldehydes with fruity flavors, diones with buttery flavors, and pyrazines with earthy/musty, roasty/burnt, and woody/papery flavors. By applying principal component analysis (PCA), Arabica and Robusta samples were separated successfully by principal component 1 (60.7% of variance), and Torrefacto and Natural Robusta EC samples were separated by principal component 2 (28.1% of total variance). With PCA, the aroma characterization of each EC sample could be observed. A very simple discriminant function using some key odorants was obtained by discriminant analysis, allowing the classification of each EC sample into its respective group with a success rate of 100%.     

Wheat quality traits and quality parameters of cooked dry white Chinese noodles

Dry white Chinese noodle (DWCN) is widely consumed in China, and genetic improvement of DWCN quality has become a major objective for Chinese wheat breeding programs. One hundred and four bread wheat cultivars and advanced lines, including 88from major Chinese wheat-producing areas, were sown in two locations for two years. Their DWCN quality, as evaluated by trained panelists, was studied to determine the relationship between wheat quality parameters and DWCN quality attributes. In general, the cultivars and advanced lines used in this study are characterized with acceptable protein content, but accompanied with weak-medium gluten strength and poor extensibility, and substantial variation is observed for all grain and DWCN quality characters. On average, Australia and USA wheat performed better DWCN quality than Chinese wheats. Simple correlation analysis indicated that both grain hardness and Farinograph water absorption were negatively associated with cooked DWCN color, appearance, smoothness, and taste. Flour whiteness and RVA peak viscosity was positively associated with all DWCN parameters, and their correlation coefficients (r) with DWCN score are 0.34 and 0.41, respectively. Their positive contributions to DWCN quality were mostly through improved color, appearance, smoothness, and taste. Farinograph mixing tolerance index (MTI) and softening were negatively associated with all DWCN quality parameters, and their correlation coefficients with DWCN score are –0.50 and–0.54, respectively. Further analysis indicated that association between protein content, Zeleny sedimentation value, Farinograph stability, and Extensograph extensibility, and DWCN score fit quadratic regression model significantly, with R² 0.12, 0.32, 0.22, and 0.20, respectively. The associations between Zeleny sedimentation value and DWCN's appearance and taste also fit quadratic regression model significantly. This suggests that to certain extent, increased protein content and gluten quality contribute positively to DWCN quality, mostly by improving palatability, elasticity, and stickiness. High flour whiteness, medium protein content, medium to strong gluten strength and good extensibility, and high starch peak viscosity are desirable for DWCN quality. Genetic improvement for flour whiteness, protein quality and starch paste viscosity would increase the DWCN quality of Chinese bread wheat cultivars. This revised version was published online in July 2006 with corrections to the Cover Date.     

Pharmacokinetics of an ampicillin-sulbactam combination after intravenous and intramuscular administration to neonatal calves

The pharmacokinetics of a 2:1 ampicillin-sulbactam combination after intravenous (i.v.) and intramuscular (i.m.) injection at a single dose rate of 20 mg/kg bodyweight (13.33 mg/kg of sodium ampicillin and 6.67 mg/kg of sodium sulbactam) were studied in 10-day-old neonatal calves (n = 10). The plasma concentration-time data of both antibiotics were best fitted to an open two-compartment model after i.v. administration. After i.m. administration, an open two-compartment model demonstrated first order absorption. The apparent volumes of distribution of ampicillin and sulbactam, calculated by the area method, were 0.20+/-0.01 and 0.18+/-0.01 L/kg, respectively, and the total body clearances were 0.51+/-0.03 and 0.21+/-0.01 L/kg h. The elimination half-lives of ampicillin after i.v. and i.m. administration were 0.99+/-0.03 and 1.01+/-0.02 h, respectively, whereas for sulbactam the half-lives were 2.24+/-0.02 and 3.44+/-0.94 h. The bioavailability after i.m. injection was high and similar for both drugs (70.31+/-0.2% for ampicillin and 68.62+/-4.44% for sulbactam). The mean peak plasma concentrations of ampicillin and sulbactam were reached at similar times (0.47+/-0.02 and 0.72+/-0.01 h, respectively) and peak concentrations were also similar but not proportional to the dose administered (17.88+/-0.91 mg/L of ampicillin and 12.92+/-0.79 mg/L of sulbactam). Both drugs had similar pharmacokinetic behaviour after i.m. administration. Since the plasma concentrations of sulbactam were consistently higher during the elimination phase of their disposition, consideration could be given to formulating the ampicillin-sulbactam combination in a ratio higher than 2:1.     

Analysis of Aggressiveness of Erwinia amylovora Using Disease-Dose and Time Relationships

ABSTRACT The aggressiveness of an extensive collection of strains of Erwinia amylovora was analyzed using immature fruit and detached pear flower assays under controlled environmental conditions. The analysis was performed by means of a quantitative approach based on fitting data to mathematical models that relate infection incidence to pathogen dose and time. Probit and hyperbolic saturation models were used for disease-dose relationships and provided information on the median effective dose (ED(50)). Values of ED(50) ranged from 10(3) to 10(6) CFU/ml (10 to 10(4) CFU per site of inoculation). A modified Gompertz model was used for disease-time relationships and provided information on the rate of infection incidence progression (r(g)) and time delayed to start of the incidence progress curve (t(0)). Values of r(g) ranged from near 0 to 1.90, and t(0) varied from 1.3 to more than 10 days. The more aggressive strains showed high r(g), low ED(50) values, and short t(0), whereas the less aggressive strains showed low r(g), high ED(50), and long t (0). The aggressiveness was dependent on plant material type and pear cultivars and was significantly different between strains of E. amylovora. Infectivity titration and kinetic analysis of progression of incidence of infections using the immature pear test and a standardized scale are proposed for assessment of strain aggressiveness. The implications of r(g), ED(50), and t(0) for the epidemiology and management of fire blight are discussed, particularly the wide range of aggressiveness among strains, the degree of host specificity observed in pear isolates, the very high infective potential of this pathogen, the independent action of pathogen cells during infection, and the possible advantage of including aggressiveness parameters into fire blight risk forecasting systems.