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Abstract  

The phase diagram of R(+)-S(-) efaroxan hydrochloride (Tfus.(R)=245.10.3C. ΔHfus.(R)=119.63.0 J g-1) shows a racemic compound. The melting temperature and melting enthalpy of the compound are: Tfus.(RS)=247.80.2C and ΔHfus. (RS)=124.62.4 J g-1. A solid ↔ solid transformation takes place at Ttrs.=1801C, ΔHtrs.=15.00.4 J g-1. This transition is observed between 3 and 97% R(+). The stability of the racemic compound already established in a previous study was confirmed by the value of Petterson's coefficient (i=1.19). The two eutectic positions at 20 and 80% R(+) that define the range over which the racemic compound is found, exclude the use of resolution methods by preferential crystallization.

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Abstract  

The physicochemical characterization of the solid-state enantiomers and racemate of efaroxan hydrochloride (C13H17N2O+Cl-, M=252.5 g mol-1) was performed by thermoanalytical methods (differential scanning calorimetry, thermogravimetry and thermomicroscopy) and spectral methods (infrared spectrometry and X-ray diffractometry). The efaroxan enantiomers and racemate were shown to be unstable near the melting point. At the beginning of the decomposition, a loss of hydrogen chloride was observed. However when sealed pans were used, the compounds decomposed at higher temperature, allowing a precise evaluation of the melting enthalpies by means of differential scanning calorimetry. The nature of the racemate and its thermal stability were assessed by evaluating its free formation enthalpy. An enantiotropic solid-solid transformation (II→I) was noted for the racemate; the reverse process (I→II) follows zero-order kinetics.

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The effect of low molecular weight (LMW) glutenin subunits (GS) in presence of high molecular weight (HMW)-GS has over SDS sedimentation volume (SDSS) and kernel elasticity is presented. Twenty-six wheat lines having different origins and classified by SDS-PAGE into 14 different LMW-GS genotypic allelic groups were analyzed. When good HMW-GS background, i.e. Glu-1 1, 2*, 7 + 9 or 17 + 18 and 5 + 10 was associated with a number of allelic variants of Glu-3 loci (LMW-GS), i.e. Glu-A3 c and b; Glu-B3 g, h, d, higher kernel modulus of elasticity and SDSS were generally present. However, when poor HMW-GS background was present, i.e. Glu-1 null, 7 + 8, 2 + 12, a poor to medium modulus of elasticity and SDSS were generally found. Glu-B3 j allelic group, which possesses the wheat-rye translocation showed a tendency to have low elastic modulus, high plastic work (WP) and low SDSS. The effects of good LMW-GS are enhanced by a good HMW-GS background, yielding higher kernel elasticity and SDSS.

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The effect of substrate water potential (Ψ W ) in root growth and proline content of maize seedlings of Tuxpeño Sequía C0 (TSC0) and Tuxpeño Sequía C8 (TSC8), sensitive and resistant to drought respectively, were evaluated. Seventy two hours old seedlings, with 5 cm root length, were maintained for 24 h in vermiculite at Ψ W between −0.03 and −2.35 MPa. Root length, fresh and dry weight, number of lateral roots and proline content were evaluated. Root enlargement of TSC0 was significantly higher than TSC8 at −0.03 MPa, but the response was opposite at low substrate Ψ W . The number of lateral roots was reduced in 23% in TSC8 at the lowest substrate Ψ W (−2.35 MPa) but it was not significantly affected in TSC0. A higher proline content was quantified in the cell division root region than in differentiation root region in both maize populations (5.64 and 6.96 μmol 100 mg −1 of dry weight in TSC0 and TSC8, respectively); and Ψ W between −0.65 and −2.35 MPa induced a drastic and significant increase of proline content in both populations. The statistical interaction between maize population, substrate Ψ W , and root region was highly significant (P≤0.0039) for proline content. The results demonstrated that eight cycles of recurrent selection of Tuxpeño for drought tolerance induced a reduction of the number of secondary roots and proline content in the differentiation root region, but a proline increase in the cell division region when root seedling grow under no restrictive water conditions (Ψ W =−0.03 MPa), beside recurrent selection modified root reaction to low substrate Ψ W by accumulation of dry matter and proline.

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Glutenin subunit alleles at the Glu-D3 locus and their effects on dough properties, pan bread, and dry white Chinese noodle (DWCN) qualities were investigated using 106 winter and facultative wheat cultivars and advanced lines. Allele Glu-D3c (42.5%) was the most frequent glutenin subunit, followed by Glu-D3b (25.5%) and Glu-D3a (23.6%). Glu-D3d and Glu-D3f occurred in only three and six cultivars, respectively. The effect of Glu-D3 was significant forDWCNquality, accounting for up to 16% of the variation, but there were no significant differences between individual Glu-D3 alleles on dough properties and qualities of DWCNand pan bread. Interaction effects Glu-A1 × Glu-D3 and Glu-B1 × Glu-D3 were significant for DWCN quality and loaf volume. More work is needed to understand the effects of Glu-D3 variation on the determination of dough properties and end-use quality.

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Cereal Research Communications
Authors: Cecilia Peña-Valdivia, Adriana Sánchez-Urdaneta, Carlos Trejo, J. Aguirre R., and Elizabeth Cárdenas S.

The effect of substrate water potential (Ψ W ) in anatomical characteristics of root seedlings of maize Tuxpeño Sequía C0 (TSC0), drought sensitive, and Tuxpeño Sequía C8 (TSC8), drought resistant, were evaluated. Seventy two hours old seedlings, having an average root length of 5 cm, were maintained for 24 h in vermiculite at Ψ W of −0.03, −0.65, −1.48 and −2.35 MPa. Anatomical characteristics from both differentiation and cell division root regions were evaluated. Lowest Ψ W diminished significantly (P=0.0020) transverse root area, number of cells in the cortex parenchyma, thickness of epidermis, exodermis and cortex, and number of metaxylem vessels in both maize populations. Number of metaxylem vessels and cortex thickness was affected only in TSC0 (15% in both cases); in contrast, the number of cortex cells in the differentiation root region increased 25%, independently of the Ψ W , and the thickness of the xylem wall from the differentiation root region increased 93% at Ψ W of −2.35 MPa, in both maize populations. Results suggest that the recurrent selection for drought tolerance induced a significant thinning of the protoderm (78%), endodermis (17%), and xylem vessels (14%) in Tuxpeño maize root and modified the response of root to substrate Ψ W , including several anatomical changes.

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The allelic variation for Glu-1, Glu-3 loci and presence of IBL-1RS translocation was determined in 126 spring wheat accessions. The most common alleles at Glu-1 loci were Glu-A1b (59.52%), Glu-B1c (41.26%), and Glu-D1d (57.14%) and at Glu-3 loci were Glu-A3c (56.45%), Glu-B3j (29.36%), and Glu-D3b (76.98%). Modern Pakistani wheat varieties carried superior alleles at Glu-1 and Glu-3 loci for bread-making quality and had no negative influence of secalin protein-synthesized by 1BL-1RS translocation. For LMW-GS, the most common combination was Glu-A3c, Glu-B3j and Glu-D3b. The loci Glu-B1 and Glu-B3 had the highest allelic diversity of Glu-1 and Glu-3 loci, respectively.

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Cereal Research Communications
Authors: E. Martínez-Cruz, E. Espitia-Rangel, H. Villaseñor-Mir, J. Molina-Galán, I. Benítez-Riquelme, A. Santacruz-Varela, and R. Peña-Bautista

The influence of allelic variants of HMW Gand LMWG on viscoelastic properties of dough was evaluated in parents and 98 recombinant lines derived from the crosses Rebeca F2000 × Verano S91 and Galvez M87 × Bacanora T88. Genotypes were grown at Roque, Guanajuato during the Spring-Summer of 2008. Studied traits were mixing time, mixing stability and over-mixing tolerance, general strength of the dough and tenacity/extensibility ratio. HMWG alleles 1, 2*, 17 + 18 and 5 + 10 favored the quality of the dough and variants 2 + 12 and 7 + 9 were associated with low levels of gluten strength. A 7 + 9 allele was associated with genotypes prone to form tenacious dough. Alleles Glu-A3c, Glu-A3e, Glu-B3g and Glu-B3h from the cross Rebeca F2000 × Verano S91 affected positively the quality of gluten, while allelic variants Glu-A3b, Glu-B3h and Glu-D3c in the cross Galvez M87 × Bacanora T88 were associated with higher quality standards and its counterparts Glu-A3c, Glu-B3j and Glu-D3b were associated to lower quality parameters. Results also shown interaction among loci, hence breeders need to be aware not only of the effect of individual alleles but also its interaction.

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