Carbon isotope discrimination and water-use efficiency of six crops grown under wet and dryland conditions

Mustard (Sinapis alba L.), Argentine canola (Brassica napus L. cv. Westar), Polish canola (Brassica campestris L. cv. Tobin), pea (Pisum sativum L.), durum wheat (Triticum durum L. cv. Kyle) and soft wheat (Triticum aestivum L. cv. Fielder) were grown at Outlook, Saskatchewan, Canada, under irrigated and dryland conditions. Carbon isotope discrimination (Δ) and water-use efficiency (W), defined as grams of above ground dry matter produced per kilogram water used, were negatively correlated in the six field-grown crops. In irrigated plants Δ remained relatively constant (20–21‰) throughout the growing season. However, in dryland plants, Δ declined in response to the progressive depletion of stored soil water (Polish canola, 20-2-18-8‰; mustard, 19.9–18 5‰; pea, 19.9–17 2‰ durum wheat, 19.7–16.4‰; Argentine canola, 19.4–17.6‰; soft wheat, 19.0–17.4‰). Although there were genetic differences in Δ among the species, water availability was the major factor controlling Δ.     

Binding of <Superscript>3</Superscript>H-Concanavalin A by Normal and Transformed Cells

CERTAIN plant lectins selectively agglutinate tissue culture cells transformed by oncogenic viruses and chemical carcinogens^1–7. Agglutination of transformed cells is inhibited by certain small carbohydrates which are thought to be sterically similar to the lectin-binding sites on the cell surface. Agglutination induced by a protein from wheatgerm is inhibited by N-acetyl-glucosamine^2,3 and that induced by concanavalin A (Con A) is inhibited by α-methyl-D-glucopyranoside (α-MG⁴). Normal cells are thought also to have lectin-binding sites but in a “cryptic” form, for mild protease treatment renders them agglutinable by wheatgerm agglutinin and Con A^4,6. Transformed cells are thought to bind more lectin than untransformed cells⁵. This study was designed to test this hypothesis for jackbean lectin, Con A.     

All pyruvylated galactose in Schizosaccharomyces pombe N-glycans is present in the terminal disaccharide, 4, 6-O-[(R)-(1- carboxyethylidine)]-Galbeta1,3Galalpha1-

The large N-linked oligosaccharides released from Schizosaccharomyces pombe by endo-beta-N-acetylglucosaminidase H were examined to determine how the negatively chargedpyruvylated galactoses present (Gemmill,T.R., and Trimble,R.B., 1996, J. Biol. Chem ., 271, 25945-25949) were attached to the oligosaccharide chains. Binding of biotinylated human serum amyloid P and peanut agglutinin to native and depyruvylated S.pombe glycoproteins, respectively, indicated that the pyruvylated epitope was likely to be in the beta configuration. Examination by high- field 1H NMR of whole glycans and a disaccharide fragment released from them on partial acid hydrolysis showed that the pyruvylated galactose species was in fact beta1,3-linked to a second galactose, and this occurred an average of five to six times on nominal Gal57Man64GlcNAc N- glycans. The pyruvate-2,(4,6)Gal-beta1,3Gal epitope is chemically similar to acetaldehyde-Galbeta1,3Gal groups found on the glycoproteins from Paramyxovirus-infected bovine kidney cells (Prehm, P., Scheid,A. and Choppin,P.W. ,1979, J. Biol. Chem ., 254, 9669-9677). The 1:1 stoichiometry between pyruvate and beta-linked galactose in these S.pombe glycans indicates that either pyruvate addition to terminal beta1,3Gal is highly efficient or that pyruvylated Gal is transferred en bloc to alpha1,2-linked Gal residues in theN-linked chains. In contradiction to many galactomannan-producing fungi, which add substantial amounts of Gal in the furanose form to their glycoproteins, all detectable Gal in the large S.pombe galactomannans is in the pyranose form, as found in higher eukaryotes. The current work shows that the S.pombe outer chain structure is a poly-alpha1,6Man backbone 2- O-substituted with either Gal or the pyruvylated galactobiose and contains little alpha1,2-linked or 2-O-substituted Man. This is in contrast to the S. cerevisiae outer chain, which is poly-alpha1,6Man substituted with alpha1,2-linked Man sidechains (Ballou,C.E. ,1990, Methods Enzymol , 185, 440-470).      

The effects of nitrogen stress on the stable carbon isotope composition, productivity and water use efficiency of white spruce (Picea glauca (Moench) Voss) seedlings

A, assimilation rate
a, fractionation against ¹³C for CO₂ diffusion through air
b, net fractionation against ¹³C during CO₂ fixation
C_a, ambient CO₂ concentration
C_c, CO₂ concentration at the chloroplast
C_i, intercellular CO₂ concentration
D, vapour pressure deficit
E_n, needle transpiration rate
E_p, whole plant water use
g_w, leaf internal transfer conductance to CO₂
g_s, stomatal conductance to water vapour
L, projected leaf area
NUE, nitrogen use efficiency
PEP, phosphoenolpyruvate
Rubisco, ribulose-1,5-biphosphate carboxylase
TDR, time domain reflectometry
WUE, water use efficiency
Δ, carbon isotope discrimination
δ¹³C, carbon isotope abundance parameter
δ¹³C_a, carbon isotopic composition of atmospheric CO₂
θ, volumetric soil water content

The effect of nitrogen stress on needle δ¹³C, water-use efficiency (WUE) and biomass production in irrigated and dry land white spruce (Picea glauca (Moench) Voss) seedlings was investigated. Sixteen hundred seedlings, representing 10 controlled crosses, were planted in the field in individual buried sand-filled cylinders. Two nitrogen treatments were imposed, nitrogen stressed and fertilized. The ranking of δ¹³C of the crosses was maintained across all combinations of water and nitrogen treatments and there was not a significant genetic versus environmental interaction. The positive relationships between needle δ¹³C, WUE and dry matter production demonstrate that it should be possible to use δ¹³C as a surrogate for WUE, and to select for increased WUE without compromising yield, even in nitrogen deficient environments. Nitrogen stressed seedlings had the lowest needle δ¹³C in both irrigated and dry land conditions. There was a positive correlation between needle nitrogen content and δ¹³C that was likely associated with increased photosynthetic capacity. There was some indication that decreased nitrogen supply led to increased stomatal conductance and hence lower WUE. There was a negative correlation between intrinsic water use efficiency and photosynthetic nitrogen use efficiency (NUE). This suggests that white spruce seedlings have the ability to maximize NUE when water becomes limited. There was significant genetic variation in NUE that was maintained across treatments. Our results suggest that in white spruce, there is no detectable effect of anaplerotic carbon fixation and that it is more appropriate to use a value of 29‰ (‘Rubisco only’) for the net discrimination against ¹³C during CO₂ fixation. This leads to excellent correspondence between values of C_i/C_a derived from gas exchange measurements or from δ¹³C.     

Cloning and gene map assignment of the Xiphophorus DNA ligase 1 gene

Fishes represent the stem vertebrate condition and have maintained several gene arrangements common to mammalian genomes throughout the 450 Myr of divergence from a common ancestor. One such syntenic arrangement includes the GPI-PEPD enzyme association on Xiphophorus linkage group IV and human chromosome 19. Previously we assigned the Xiphophorus homologue of the human ERCC2 gene to linkage group U5 in tight association with the CKM locus. CKM is also tightly linked to the ERCC2 locus on human chromosome 19, leading to speculation that human chromosome 19 may have arisen by fusion of two ancestral linkage groups which have been maintained in fishes. To investigate this hypothesis further, we isolated and sequenced Xiphophorus fish genomic regions exhibiting considerable sequence similarity to the human DNA ligase 1 amino acid sequence. Comparison of the fish DNA ligase sequence with those of other species suggests several modes of amino acid conservation in this gene. A 2.2-kb restriction fragment containing part of an X. maculatus DNA ligase 1 exon was used in backcross hybrid mapping with 12 enzyme or RFLP loci. Significant linkage was observed between the nucleoside phosphorylase (NP2) and the DNA ligase (LIG1) loci on Xiphophorus linkage group VI. This assignment suggests that the association of four DNA repair-related genes on human chromosome 19 may be the result of chance chromosomal rearrangements.      

Electro-optical behaviour of CuFe2O4@rGO nanocomposite for nonenzymatic detection of uric acid via the electrochemical method

Uric acid (UA) is a blood and urine component obtained as a metabolic by-product of purine nucleotides. Abnormalities in UA metabolism cause crystal deposition as monosodium urate and lead to various diseases such as gout, hyperuricemia, Lesch–Nyhan syndrome, etc. Monitoring these diseases requires a rapid, sensitive, selective, and portable detection approach. Therefore, this study demonstrates the hydrothermal synthesis of CuFe₂O₄/reduced graphene oxide (rGO) nanocomposite for selective detection of UA. After the nanocomposite synthesis, characterization was performed by X-ray diffraction spectroscopy, Fourier transform infrared spectroscopy, Raman spectroscopy, X-ray photoelectron spectroscopy, UV–visible spectrometry, atomic force spectroscopy, scanning electron microscopy, and electrochemical analysis. Furthermore, from the electrochemical analysis using cyclic voltammetry (CV), kinetic studies were carried out by varying the scan rate to obtain the diffusion coefficient, surface concentration, and rate of charge transfer to achieve a calibration curve that indicates the quasi reversible nature of the fabricated electrode with a linear regression coefficient of oxidation (R²: 0.9992) and reduction (R²: 0.9971) peaks. Moreover, the fabricated nonenzymatic amperometric sensor to detect UA with a linearity (R²: 0.9989) of 1–400 μM was highly sensitive (2.75 × 10⁻⁴ mAμM⁻¹ cm⁻²) and had a lower limit of detection (0.01231 μM) at pH 7.5 in phosphate-buffered saline solution. Therefore, the CuFe₂O₄/rGO/ITO-based nonenzymatic sensor could detect interfering agents and spiked real bovine serum samples with higher sensitivity and selectivity for UA detection.     

An RNA folding method capable of identifying pseudoknots and base triples

MOTIVATION: Recently, we described a Maximum Weighted Matching (MWM) method for RNA structure prediction. The MWM method is capable of detecting pseudoknots and other tertiary base-pairing interactions in a computationally efficient manner (Cary and Stormo, Proceedings of the Third International Conference on Intelligent Systems for Molecular Biology, pp. 75-80, 1995). Here we report on the results of our efforts to improve the MWM method's predictive accuracy, and show how the method can be extended to detect base interactions formerly inaccessible to automated RNA modeling techniques. RESULTS: Improved performance in MWM structure prediction was achieved in two ways. First, new ways of calculating base pair likelihoods have been developed. These allow experimental data and combined statistical and thermodynamic information to be used by the program. Second, accuracy was improved by developing techniques for filtering out spurious base pairs predicted by the MWM program. We also demonstrate here a means by which the MWM folding method may be used to detect the presence of base triples in RNAs. AVAILABILITY: http://www.cshl.org/mzhanglab/tabaska/j axpage. html CONTACT: tabaska@cshl.org