Cluster-root formation, carboxylate exudation and proton release of Lupinus pilosus Murr. as affected by medium pH and P deficiency

The study examined the interactive effect of pH and P supply on cluster-root formation, carboxylate exudation and proton release by an alkaline-tolerant lupin species (Lupinus pilosus Murr.) in nutrient solution. The plants were exposed to 1 (P₁, deficient) and 50 μM P (P₅₀, adequate) for 34 days in nutrient solution at either pH 5.6 or 7.8. Plant biomass was not influenced by pH at P₁, but at P₅₀ shoot and root dry weights were 23 and 18% higher, respectively, at pH 7.8 than at pH 5.6. There was no significant difference in plant biomass between two P treatments regardless of medium pH. Phosphorus deficiency increased significantly the number of the second-order lateral roots compared with the P₅₀ treatment. Both total root length and specific root length of plants grown at pH 5.6 were higher than those at pH 7.8 regardless of P supply. Cluster roots were formed at P₁, but cluster-root number was 2-fold higher at pH 7.8 than pH 5.6. Roots released 16 and 31% more protons at pH 5.6 and 7.8, respectively, in P₁ than in P₅₀ treatments, and the rate of proton release followed the similar pattern. At pH 5.6, citrate exudation rate was 0.39 μmol g⁻¹ root DW h⁻¹ at P₁, but was under the detection limit at P₅₀; at pH 7.8, it was 2.4-fold higher in P₁ than in P₅₀ plants. High pH significantly increased citrate exudation rate in comparison to pH 5.6. The uptake of anions P and S was inhibited at P₁ and high pH increased cations Na, Mg and Ca uptake. The results suggested that enhanced cluster-root formation, proton release and citrate exudation may account for the mechanism of efficient P acquisition by alkaline-tolerant L. pilosus well adapted to calcareous soils. Cluster-root formation and citrate exudation in L. pilosus can be altered by medium pH and P deficiency. Phosphorus deficiency-induced proton release may be associated with the reduced anion uptake, but high pH-induced proton release may be partly attributed to increased cation uptake.     

Five labdane diterpenoids from the seeds of Aframomum zambesiacum

Five labdane diterpenoids, (3-5), zambesiacolactone A (7) and zambesiacolactone B (8), were isolated from the seeds of Aframomum zambesiacum (Baker) K. Schum., along with five known labdanes and a linear sesquiterpene, nerolidol. Their structures were elucidated by spectroscopic analysis. Their antiplasmodial activity was evaluated in vitro against Plasmodium falciparum. Compound 3 was the most active with an IC(50) value of 4.97 microM.     

PQN and DQN: algorithms for expression microarrays

An ideal expression algorithm should be able to tell truly different expression levels with small false positive errors and be robust to assay changes. We propose two algorithms. PQN is the non-central trimmed mean of perfect match intensities with quantile normalization. DQN is the non-central trimmed mean of differences between perfect match and mismatch intensities with quantile normalization. The quantiles for normalization can be either empirical or theoretical. When array types and/or assay change in a study, the normalization to common quantiles at the probe set level is essential. We compared DQN, PQN, RMA, GCRMA, DCHIP, PLIER and MAS5 for the Affymetrix Latin square data and our data of two sets of experiments using the same bone marrow but different types of microarrays and different assay. We found the computation for AUC of ROC at affycomp.biostat.jhsph.edu can be improved.     

Controlling Posture and Vergence Eye Movements in Quiet Stance: Effects of Thin Plantar Inserts

The purpose of this study was to assess properties of vergence and saccade eye movements as well as posture in quiet stance, and the effects of thin plantar inserts upon postural and oculomotor control. The performances of 36 young healthy subjects were recorded by a force platform and an eye tracker in three testing conditions: without plantar stimulation, with a 3 millimetre-thick plantar insert, either a Medial or a Lateral Arch Support (MAS / LAS). The results showed a decrease of the Surface and Variance of Speed and a more posterior position of the CoP with either stimulation compared with the control condition. The fractal analysis showed a decrease with MAS. Wavelet analysis in the time-frequency domain revealed an increase in the Cancelling Time of the low frequency band with MAS. These results suggest a better stability for a lower energy cost. Concerning eye movements, the inserts influenced only vergence (not saccades): MAS caused an increase of the phasic amplitude of divergence, and conversely a decrease of the tonic amplitude. In contrast, LAS caused an increase of the tonic amplitude of convergence. Thus, MAS renders divergence less visually driven, while LAS renders convergence more visually driven. We conclude that the CNS uses the podal signal for both postural and vergence control via specific mechanisms. Plantar inserts have an influence upon posture and vergence movements in a different way according to the part of the foot sole being stimulated. These results can be useful to clinicians interested in foot or eye.     

In vitro detachment of bacteria from ruminal digesta by buffered sodium oleate solutions

The effectiveness of a buffered sodium oleate solution was evaluated for detaching bacteria from ruminal digesta samples. A response surface derived from an octagonal design was used to determine the pH and concentration combination for maximum detachment of total and cellulolytic bacteria. The total number of bacteria detached increased up to 81% over control with treatment of a pH 8.8 and 1.5% sodium oleate solution. The recovery of cellulolytic bacteria was decreased to 35% of control with treatment of a pH 9.0 and 0.1% sodium oleate solution. Attempts to improve the recovery of viable bacteria exposed to sodium oleate solutions were unsuccessful. This response surface design identified an optimal pH and concentration that were consistent with existing information regarding detachment of total bacteria, and suggested that sodium oleate, at the concentrations tested, was toxic to the cellulolytic population of the rumen.     

1,2-Cyclohexanedione modification of arginine residues in egg-white riboflavin-binding protein

1. Reaction of 1,2-cyclohexanedione with arginine residues of egg white riboflavin-binding protein results in a loss of the binding activity. 2. In borate buffer pH 8.0, with 0.15 M cyclohexanedione, the inactivation proceeds with a pseudo-first-order rate constant 0.084 hr.-1. 3. At least 65% of lost riboflavin binding capacity can be recovered on 12 hr incubation in 0.5 M hydroxylamine pH 7.0. 4. All 5 arginine residues are modified, 2-3 of them seem to react much easier than others. 5. The correlation between modification of arginines and protein inactivation, as analyzed by kinetic and statistical methods, suggests that one of low-reactivity residues is "essential" for riboflavin binding. 6. In the holoprotein, one arginine residue is almost completely protected from 1,2-cyclohexanedione modification. 7. Riboflavin does not dissociate from holoprotein, even on prolongated incubation with the reagent. 8. The protected arginine residue seems to be located in the riboflavin binding pocket of protein macromolecule.     

Mutation mechanism of chlorophyll-less barley mutant <Emphasis Type="Italic">NYB</Emphasis>

NYB is chlorophyll-less barley mutant, which is controlled by a recessive nuclear gene. The mutation mechanism is revealed. The activities of enzymes transforming 5-aminolevulinic acid into protochlorophyllide were the same in both NYB and the wild type (WT), but the activity of the protochlorophyllide oxidoreductase (POR) in WT was much higher than that of NYB. Most of the photosystem 2 apoproteins were present in both WT and NYB, suggesting that the capability of protein synthesis was probably fully preserved in the mutant. Thus chlorophyll (Chl) biosynthesis in NYB was hampered at conversion form protochlorophyllide (Pchlide) into chlorophyllide. The open reading frame of porB gene in NYB was inserted with a 95 bp fragment, which included a stop codon. The NYB mutant is a very useful material for studies of Chl biosynthesis, chloroplast signalling, and structure of light-harvesting POR-Pchlide complex (LHPP).     

Toward using δ13C of ecosystem respiration to monitor canopy physiology in complex terrain

In 2005 and 2006, air samples were collected at the base of a Douglas-fir watershed to monitor seasonal changes in the delta13CO2 of ecosystem respiration (delta13C(ER)). The goals of this study were to determine whether variations in delta13C(ER) correlated with environmental variables and could be used to predict expected variations in canopy-average stomatal conductance (Gs). Changes in delta13C(ER) correlated weakly with changes in vapor pressure deficit (VPD) measured 0 and 3-7 days earlier and significantly with soil matric potential (psi(m)) (P value <0.02) measured on the same day. Midday G (s) was estimated using sapflow measurements (heat-dissipation method) at four plots located at different elevations within the watershed. Values of midday Gs from 0 and 3-7 days earlier were correlated with delta13C(ER), with the 5-day lag being significant (P value <0.05). To examine direct relationships between delta13C(ER) and recent Gs, we used models relating isotope discrimination to stomatal conductance and photosynthetic capacity at the leaf level to estimate values of stomatal conductance ("Gs-I") that would be expected if respired CO2 were derived entirely from recent photosynthate. We compared these values with estimates of Gs using direct measurement of transpiration at multiple locations in the watershed. Considering that the approach based on isotopes considers only the effect of photosynthetic discrimination on delta13C(ER), the magnitude and range in the two values were surprisingly similar. We conclude that: (1) delta13C(ER) is sensitive to variations in weather, and (2) delta13C(ER) potentially could be used to directly monitor average, basin-wide variations in Gs in complex terrain if further research improves understanding of how delta13C(ER) is influenced by post-assimilation fractionation processes.     

Experimental evaluation of calcein and alizarin red S for immersion marking of silver carp Hypophthalmichthys molitrix (Valenciennes, 1844)

Calcein (CAL) and alizarin red S (ARS) at concentrations of 50–200 and 150–300 mg/L, respectively, were used for immersion marking of juvenile silver carp Hypophthalmichthys molitrix (79.65 ± 2.11 mm total length, mean ± SD). The marked fish were kept in separate tanks (0.012 individuals per litre, rearing temperature 18.4–25.7°C) for 360 days. Each experimental treatment group consisted of three replicates (16 individuals per replicate). Immersion for 24 h produced detectable marks in the sagittae, lateral line and non‐lateral line scales, and fin rays (dorsal, pectoral, ventral, anal, and caudal) at 360 days post‐marking. Acceptable marks in the sagittae were observed for CAL at concentrations of 150–200 mg/L and for ARS at concentrations of 200–300 mg/L. Fluorescent marks were poorly visible in all non‐lateral line scales from both the CAL‐ and ARS‐treated groups. Acceptable fluorescent marks in the lateral line scales and fin rays were detected for CAL at concentrations of 150–200 and 100–200 mg/L, respectively, and for ARS at concentrations of 200–300 and 150–300 mg/L, respectively. In particular, optimal marks were observed at the highest concentrations investigated in lateral line scales (200 mg/L CAL, 300 mg/L ARS) and fin rays (200 mg/L CAL, 200–300 mg/L ARS). There was no significant difference in the survival or growth of marked fish compared to controls throughout the experiment (P > 0.05).     

Estimation of genetic parameters for disease‐resistance traits in Cynoglossus semilaevis (Günther, 1873)

The objective of this study was to estimate genetic parameters for three traits based on 28 Cynoglossus semilaevis families approximately 6 months of age (at least 5 cm total length), including trait_1 (survival of 26 families, 3434 individuals in total subjected to challenge tests with Edwardsiella tarda), trait_2 (survival of 20 families, 2016 individuals in total subjected to challenge tests with Vibrio anguillarum) and trait_3 (survival of 27 families, 9340 individuals tagged at circa 180 days of age and reared in indoor ponds for circa another 5 months). The result showed that there were large differences in the survival of the families after challenge (11.11–65.31% for E. tarda and 9.18–70.54% for V. anguillarum). Additionally, the survival of families reared in indoor ponds was also different, varying from 21.00% to 73.67%. Heritabilities of the three traits varied from 0.14 to 0.26, as estimated by the linear model (LM) and the threshold model (TM). The trait_1 heritabilities (0.26 and 0.19 estimated by LM and TM) were higher than those of the others (0.20 and 0.23 estimated by LM, 0.14 and 0.19 estimated by TM). The estimates of heritabilities using LM were consistently higher than those of TM in this study. There were significant medium genetic correlations of 0.44 and 0.42 between trait_1 and trait_2 obtained from LM and TM (P < 0.05). However, very low and non‐significant genetic correlations of trait_1 and trait_3 (?0.10 for LM, ?0.05 for TM), as well as those of trait_2 and trait_3 (0.05 for LM, 0.04 for TM) were obtained. Therefore, indirect selection for trait_1 and trait_2 was effective, but almost ineffectual for trait_1 and trait_3 as well as trait_2 and trait_3. Otherwise, there was no significant difference in the predictive abilities of LM and TM. Two families resistant to both Edwardsiella tarda and Vibrio anguillarum were selected plus one family resistant to both Vibrio anguillarum and naturally infected by unknown pathogens through family selection. As there was very low and non‐significant genetic correlation of trait_3 and trait_1 as well as trait_2, superior strains are anticipated with the ability to resist two or more kinds of diseases, through the crossing of families selected for the three traits described above. The results support the hypothesis that genetic variation exists for disease survival, which could be used to design a breeding program for selecting strains of Cynoglossus semilaevis with high disease resistance.