Effects of temperature at constant air dew point on leaf carboxylation efficiency and CO 2 compensation point of different leaf types

The effect of temperature on photosynthesis at constant water-vapor pressure in the air was investigated using two sclerophyll species, Arbutus unedo and Quercus suber , and one mesophytic species, Spinacia oleracea . Photosynthesis and transpiration were measured over a range of temperatures, 20–39° C. The external concentration of CO 2 was varied from 340 μbar to near CO 2 compensation. The initial slope (carboxylation efficiency, CE) of the photosynthetic response to intercellular CO 2 concentration, the CO 2 compensation point (Γ), and the extrapolated rate of CO 2 released into CO 2 -free air ( R i ) were calculated. At an external CO 2 concentration of 320–340 μbar CO 2 , photosynthesis decreased with temperature in all species. The effect of temperature on Γ was similar in all species. While CE in S. oleracea changed little with temperature, CE decreased by 50% in Q. suber as temperature increased from 25 to 34° C. Arbutus unedo also exhibited a decrease in CE at higher temperatures but not as marked as Q. suber . The absolut value of R i increased with temperature in S. oleracea , while changing little or decreasing in the sclerophylls. Variations in Γ and R i of the sclerophyll species are not consistent with greater increase of respiration with temperature in the light in these species compared with S. oleracea .Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/47470/1/425_2004_Article_BF00397389.pd

Decoding motor responses from the EEG during altered states of consciousness induced by propofol

Contains fulltext : 157484.pdf (publisher's version ) (Open Access)Objective. Patients undergoing general anesthesia may awaken and become aware of the surgical procedure. Due to neuromuscular blocking agents, patients could be conscious yet unable to move. Using brain–computer interface (BCI) technology, it may be possible to detect movement attempts from the EEG. However, it is unknown how an anesthetic influences the brain response to motor tasks. Approach. We tested the offline classification performance of a movement-based BCI in 12 healthy subjects at two effect-site concentrations of propofol. For each subject a second classifier was trained on the subject’s data obtained before sedation, then tested on the data obtained during sedation (‘transfer classification’). Main results. At concentration 0.5 μ g ml -1 , despite an overall propofol EEG effect, the mean single trial classification accuracy was 85% (95% CI 81%- 89%), and 83% (79%-88%) for the transfer classification. At 1.0 μ g ml -1 , the accuracies were 81% (76%-86%), and 72% (66%-79%), respectively. At the highest propofol concentration for four subjects, unlike the remaining subjects, the movement-related brain response had been largely diminished, and the transfer classification accuracy was not significantly above chance. These subjects showed a slower and more erratic task response, indicating an altered state of consciousness distinct from that of the other subjects. Significance. The results show the potential of using a BCI to detect intra-operative awareness and justify further development of this paradigm. At the same time, the relationship between motor responses and consciousness and its clinical relevance for intraoperative awareness requires further investigation.9 p

Quantitative trait loci for carbon isotope discrimination are repeatable across environments and wheat mapping populations

Wheat productivity is commonly limited by a lack of water essential for growth. Carbon isotope discrimination (Δ), through its negative relationship with transpiration efficiency, has been used in selection of higher wheat yields in breeding for rainfed environments. The potential also exists for selection of increased Δ for improved adaptation to irrigated and high rainfall environments. Selection efficiency of Δ would be enhanced with a better understanding of its genetic control. Three wheat mapping populations (Cranbrook/Halberd, Sunco/Tasman and CD87/Katepwa) containing between 161 and 190 F1-derived, doubled-haploid progeny were phenotyped for Δ and agronomic traits in 3–5 well-watered environments. The range for Δ was large among progeny (c. 1.2–2.3‰), contributing to moderate-to-high single environment (h 2 = 0.37–0.91) and line-mean (0.63–0.86) heritabilities. Transgressive segregation was large and genetic control complex with between 9 and 13 Δ quantitative trait loci (QTL) identified in each cross. The Δ QTL effects were commonly small, accounting for a modest 1–10% of the total additive genetic variance, while a number of chromosomal regions appeared in two or more populations (e.g. 1BL, 2BS, 3BS, 4AS, 4BS, 5AS, 7AS and 7BS). Some of the Δ genomic regions were associated with variation in heading date (e.g. 2DS, 4AS and 7AL) and/or plant height (e.g. 1BL, 4BS and 4DS) to confound genotypic associations between Δ and grain yield. As a group, high Δ progeny were significantly (P < 0.10–0.01) taller and flowered earlier but produced more biomass and grain yield in favorable environments. After removing the effect of height and heading date, strong genotypic correlations were observed for Δ and both yield and biomass across populations (r g = 0.29–0.57, P < 0.05) as might be expected for the favorable experimental conditions. Thus selection for Δ appears beneficial in increasing grain yield and biomass in favorable environments. However, care must be taken to avoid confounding genotypic differences in Δ with stature and development time when selecting for improved biomass and yield especially in environments experiencing terminal droughts. Polygenic control and small size of individual QTL for Δ may reduce the potential for QTL in marker-assisted selection for improved yield of wheat

Detection of attempted movement from the EEG during neuromuscular block: proof of principle study in awake volunteers

Brain-Computer Interfaces (BCIs) have the potential to detect intraoperative awareness during general anaesthesia. Traditionally, BCI research is aimed at establishing or improving communication and control for patients with permanent paralysis. Patients experiencing intraoperative awareness also lack the means to communicate after administration of a neuromuscular blocker, but may attempt to move. This study evaluates the principle of detecting attempted movements from the electroencephalogram (EEG) during local temporary neuromuscular blockade. EEG was obtained from four healthy volunteers making 3-second hand movements, both before and after local administration of rocuronium in one isolated forearm. Using offline classification analysis we investigated whether the attempted movements the participants made during paralysis could be distinguished from the periods when they did not move or attempt to move. Attempted movement trials were correctly identified in 81 (68-94)% (mean (95% CI)) and 84 (74-93)% of the cases using 30 and 9 EEG channels, respectively. Similar accuracies were obtained when training the classifier on the participants' actual movements. These results provide proof of the principle that a BCI can detect movement attempts during neuromuscular blockade. Based on this, in the future a BCI may serve as a communication channel between a patient under general anaesthesia and the anaesthesiologist

Applicability of three anti-PrP peptide sera including staining of tonsils and brainstem of sheep with scrapie

Three rabbit antibodies (R521, R505, R524) were produced, and raised to synthetic peptides corresponding to residues 94-105, 100-111, and 223-234, respectively, of the sheep prion protein (PrP). Epitope mapping analysis revealed the monospecific character of antisera R505 and R524. In addition to the amino acid sequence against which it was raised, R521 also recognized Other small epitopes. ELISA and radio-immunoprecipitation were used to assess the relative immunoreactivities of the antisera to the normal sheep prion protein (PrP(c)). Highest reactivity was found for R521, followed by R505 and R524. According to Western blot analysis, all three sera specifically reacted with the prion proteins PrP(sc) and PrP27-30, extracted from the brain stem of a scrapie-affected sheep. Yet, with R505 not all of the lower molecular weight deglycosylated forms could be detected. Contrary to the immunoreactivities found with the PrP(sc) and PrP27-30 isoforms, only R521 recognised PrP(c) from a healthy sheep. The usefulness of all three anti-peptide sera in the immunohistochemical detection of PrP(sc) in brain stem and tonsils of scrapie-affected sheep was demonstrated and compared with an established rabbit anti-PrP serum. (C) 2000 Wiley-Liss, Inc