Phenomics allows identification of genomic regions affecting maize stomatal conductance with conditional effects of water deficit and evaporative demand

Stomatal conductance is central for the trades‐off between hydraulics and photosynthesis. We aimed at deciphering its genetic control and that of its responses to evaporative demand and water deficit, a nearly impossible task with gas exchanges measurements. Whole‐plant stomatal conductance was estimated via inversion of the Penman–Monteith equation from data of transpiration and plant architecture collected in a phenotyping platform. We have analysed jointly 4 experiments with contrasting environmental conditions imposed to a panel of 254 maize hybrids. Estimated whole‐plant stomatal conductance closely correlated with gas‐exchange measurements and biomass accumulation rate. Sixteen robust quantitative trait loci (QTLs) were identified by genome wide association studies and co‐located with QTLs of transpiration and biomass. Light, vapour pressure deficit, or soil water potential largely accounted for the differences in allelic effects between experiments, thereby providing strong hypotheses for mechanisms of stomatal control and a way to select relevant candidate genes among the 1–19 genes harboured by QTLs. The combination of allelic effects, as affected by environmental conditions, accounted for the variability of stomatal conductance across a range of hybrids and environmental conditions. This approach may therefore contribute to genetic analysis and prediction of stomatal control in diverse environments.     

4-N-Alkanoyl and 4-N-alkyl gemcitabine analogues with NOTA chelators for 68-gallium labelling

The conjugation of 4-N-(3-aminopropanyl)-2′-deoxy-2′,2′-difluorocytidine with 2-(p-isothiocyanatobenzyl)-1,4,7-triazacyclononane-1,4,7-triacetic acid (SCN-Bn-NOTA) ligand in 0.1?M Na₂CO₃ buffer (pH 11) at ambient temperature provided 4-N-alkylgemcitabine-NOTA chelator. Incubation of latter with excess of gallium(III) chloride (GaCl₃) (0.6?N AcONa/H₂O, pH?=?9.3) over 15?min gave gallium 4-N-alkylgemcitabine-NOTA complex which was characterized by HRMS. Analogous [⁶⁸Ga]-complexation of 4-N-alkylgemcitabine-NOTA conjugate proceeded with high labeling efficiency (94%–96%) with the radioligand almost exclusively found in the aqueous layer (～95%). The high polarity of the gallium 4-N-alkylgemctiabine-NOTA complex resulted in rapid renal clearance of the ⁶⁸Ga-labelled radioligand in BALB/c mice.     

Step and ramp induction of myocardial ischemia: comparison of in vivo and in silico results.

This study tested the robustness of our computational model of myocardial metabolism by comparing responses to two different inputs with experimental data obtained in pigs under similar conditions. Accordingly, an abrupt and a gradual reduction in coronary flow of similar magnitude were implemented and used as model input. After flow reductions reached 60% from control values, ischemia was kept constant for 60 min in both groups. Our hypotheses were that: (1) these two flow-reduction profiles would result in different transients (concentrations and flux rates) while having similar steady-state values and (2) our model-simulated responses would predict the experimental results in an anesthetized swine model of myocardial ischemia. The two different ischemia-induction patterns resulted in the same decrease in steady-state MVO2 and in similar steady-state values for metabolite concentrations and flux rates at 60 min of ischemia. While both the simulated and experimental results showed decreased glycogen concentration, accumulation of lactate, and net lactate release with ischemia, the onset of glycogen depletion and the switch to lactate efflux were more rapid in the experiments than in the simulations. This study demonstrates the utility of computer models for predicting experimental outcomes in studies of metabolic regulation under physiological and pathological conditions.     

Mitochondrial DNA variation and genetic structure in Old-World populations of Drosophila subobscura

To discover the relation between mitochondrial DNA (mtDNA) polymorphism and the geographic population structure of Drosophila subobscura previously established for other genetic traits, a wide Paleartic survey was carried out. A total of 24 nucleomorphs was observed among 261 isofemale lines assayed by 11 restriction endonucleases with 38 different sites in the mtDNA cleavage map. The differentiation of the Canary Islands populations (delta = 0.0119) compared with the mean among all the other continental and insular populations (delta = 0.0002) is striking. Both the great divergence among Canary Islands nucleomorphs (delta = 0.021) compared with the maximum nucleomorph distance in all other populations (delta = 0.017) and the abundance of endemic nucleomorphs (11) on the Canary Islands (50% of the total number of different nucleomorphs found in the entire distribution area) suggest that this molecular differentiation most probably results from the very old age of the Canary Islands populations rather than from drift and founder effects.     

Structure and expression of genes coding for xylan-degrading enzymes of Bacillus pumilus

The complete nucleotide sequence of the beta-xylosidase gene (xynB) of Bacillus pumilus IPO and its flanking regions was established. A 1617-bp open reading frame for beta-xylosidase, a homodimer enzyme, was observed. The amino acid sequence of the N-terminal region and the molecular mass 62607 Da) of the beta-xylosidase subunit, deduced from the DNA sequence, agreed with the result obtained with the purified enzyme. The Shine-Dalgarno sequence was found 8 bp upstream of the initiation codon, ATG. The xylanase gene (xynA) of the same strain was 4.6 kbp downstream of the 3' end of xynB, and its DNA sequence was reported in our previous paper [Fukusaki, E., Panbangred, W., Shinmyo, A. & Okada, H. (1984) FEBS Lett. 171, 197-201]. The results of the Northern hybridization suggested that the mRNA of xynA and xynB were produced separately. The 5' and 3' ends of the xynA and xynB gene were mapped with nuclease S1. The '-10' regions for promoter sequences of both genes were similar to the consensus sequence for B. subtilis RNA polymerases, the '-35' regions were different from all the known promoters for B. subtilis RNA polymerases.     

Human enzyme polymorphism on the Canary Islands. I. Gran Canaria Island population

Genetic polymorphism of seven red cell enzymes was examined in two Canary Island populations and in an Iberian peninsula sample. The more isolated insular population shows a considerable gene frequency heterogeneity when compared with the peninsular sample but both are within the range of European populations. The presence of certain rare alleles normally associated with blacks suggests an African component in the Canarian populations.     

Biodelignification of Lemon Grass and Citronella Bagasse by White-Rot Fungi

Twelve white-rot fungi were grown in solid-state culture on lemon grass (Cymbopogon citratus) and citronella (Cymbopogon winterianus) bagasse. The two lignocellulosic substrates had 11% permanganate lignin and a holocellulose fraction of 58%. After 5 to 6 weeks at 20°C, nine fungi produced a solid residue from lemon grass with a higher in vitro dry matter enzyme digestibility than the original bagasse; seven did the same for citronella. The best fungus for both substrates was Bondarzewia berkeleyi; it increased the in vitro dry matter enzyme digestibility to 22 and 24% for lemon grass and citronella, respectively. The increases were correlated with weight loss and lignin loss. All fungi decreased lignin contents: 36% of the original value for lemon grass and 28% for citronella. Practically all fungi showed a preference for hemicellulose over cellulose.     

Bacterial chemoattraction towards jasmonate plays a role in the entry of Dickeya dadantii through wounded tissues

Jasmonate is a key signalling compound in plant defence that is synthesized in wounded tissues. In this work, we have found that this molecule is also a strong chemoattractant for the phythopathogenic bacteria Dickeya dadantii (ex- Erwinia chysanthemi ). Jasmonic acid induced the expression of a subset of bacterial genes possibly involved in virulence/survival in the plant apoplast and bacterial cells pre-treated with jasmonate showed increased virulence in chicory and Saintpaulia leaves. We also showed that tissue wounding induced bacterial spread through the leaf surface. Moreover, the jasmonate-deficient aos1 Arabidopsis thaliana mutant was more resistant to bacterial invasion by D. dadantii than wild-type plants. These results are consistent with the hypothesis that sensing jasmonic acid by this bacterium helps the pathogen to ingress inside plant tissues.