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A novel HMW-GS of Dx5** with slightly faster migration rate than that of Dx5, was found in a Tibet bread wheat landrace using SDS-PAGE. Moreover, Dx5** is the subunit with the fastest migration rate in Glu-Dx locus. The gene for this subunit was isolated and its sequence was obtained in the present study. This gene was very similar to Dx5 both in nucleotide and deduced amino acid sequence. At the nucleotide sequence level, Dx5** different from Dx5 by the deletion of a 27 bp fragment and two nucleotide replacements at position 353(G/C) and 692(C/G), respectively. At the amino acid sequence level, Dx5** different from Dx5 by the deletion of a hexaploid (LGQGQQ) and a tripeptide (GQQ) repetitive motif and two amino acid replacements at position 118(C/S) and 231(A/G), respectively. These results suggested that the Dx5** was a derivation of Dx5 and was formed by replication slippage. Moreover, the specific cysteine (C) located at the beginning of the repetitive domain of Dx5, which proved to be critical for the end-use quality of wheat flours, was replaced by serine (S) in Dx5**.

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Abstract  

The thermal behavior of rutin extracted from the buds of Sophora japonica L. by different methods and conditions have been investigated using TG and DTG. The results showed that every sample had different mass loss, curve shape, and peak location related to varied extraction technology. The TG-DTG characteristics of the rutin sample extracted by alkali-dissolution and acid-sedimentation with the solution adjusted to pH 9 and simply borax as stabilizer were highly similar to that of standard rutin, with the maximal purity determined by spectrophotometry. Therefore, the TG-DTG patterns could be served to characterize rutin extracted from the buds of Sophora japonica L.

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The thermal decomposition studies for two palladium(II) complexes Pd(apyr)2Cl2 and Pd(pmpa)Cl2 (apyr=1–aminopyrene and pmpa=N–(2–pyridylmethylene)–1–pyrenylamine) were carried out in pure nitrogen using TG-DTG techniques. The non-isothermal kinetic parameters for the two complexes were evaluated employing the method suggested by Málek, esták, Koga et al. Based on the above results, thermal behaviour of the complexes were carefully discussed, which showed that not only the parameters value, but also the decomposition pattern and mechanism for complex 1 are different from complex 2.

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Aegilops tauschii is the generally accepted D genome diploid donor of hexaploid wheat. The significance of Ae. tauschii HMW-GS genes on bread-making properties of bread wheat has been well documented. Among them, Ae. tauschii HMW-GS Dx5 t +Dy12 t was thought as the pair with potentially value in endowing synthetic hexaploid wheat with good end-use qualities. In this paper, we isolated and sequenced genes Dx5 t and Dy12 t from Ae. tauschii accession As63. Amino acid sequence comparison indicated that Dy12 t from Ae. tauschii is more similar to Dy10 rather than Dy12 of bread wheat. The sequence of Dx5 t in Ae. tauschii accession As63 showed higher similarity to that of Dx5 in bread wheat than others. However, it is notable that Dx5 t lacked the additional cysteine residue in Dx5, which is responsible for good bread-making quality in common wheat. Moreover, compared to Dx5, Dx5 t has an extra hexpeptide repetitive motif unit (SGQGQQ) as well as five amino acid substitutions.

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Influence of different maturity stages and treatments of ethephon, exogenous ABA, and fluridone on the ripening and hormone level of ‘Zhonghuashoutao’ peach during development and post-harvest storage were investigated. The accumulation of endogenous ABA appeared at the onset of ripening and peaked at two weeks before harvest. Fruit firmness decreased, while ethylene release and SSC/TA increased sharply after a maximum peak of ABA, which have triggered the initiation of the fruit ripening. The fruits, harvested at 170 d when fruits have ripened and stored at 20 °C, showed an ethylene climacteric peak, and the pulp started softening normally, and the SSC/TA value increased. Compared with them, the immature green fruits harvested at other dates, could not mature normally due to the lack of normal reciprocity between ABA and ethylene. The ethylene release was promoted by the treatment of exogenous ABA and ethephon during ripening until the endogenous ABA reached a maximum value. However, fluridone treatment showed an inhibitory effect. The above-mentioned changes occurred again in the peach fruits after harvest. The results indicated that both ABA and ethylene play important roles in peach ripening, and their action depended on the ripening stage of peach.

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The thermal decomposition of Zn[NFA]2 5H2O (NFA=C16H18FN3O3, norfloxacin) and its kinetics were studied under non-isothermal conditions in air by TG-DTG and DTA methods. The intermediate and residue for each decomposition were identified from the TG curve. The non-isothermal kinetic data were analyzed by means of the Achar method and the Madhusudanan-Krishnan-Ninan (MKN) method. The possible reaction mechanisms were investigated by comparing the kinetic parameters. The kinetic equation for the second stage can be expressed as d/dt=Aexp(–E/RT)(1–).

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Cereal Research Communications
Authors: L. Zhang, Z. Yan, S. Dai, Q. Chen, Z. Yuan, Y. Zheng, and D. Liu

Two experiments to investigate the crossability of Triticum turgidum with Aegilops tauschii are described. In the first experiment, 372 wide hybridization combinations were done by crossing 196 T. turgidum lines belonging to seven subspecies with 13 Ae. tauschii accessions. Without embryo rescue and hormone treatment, from the 66220 florets pollinated, 3713 seeds were obtained, with a mean crossability percentages of 5.61% which ranged from 0 to 75%. A lot of hybrid seeds could germinate and produce plants. Out of 372 combinations, 73.12% showed a very low crossability less than 5%, 23.39% showed the crossability of 5–30%, 2.69% showed the crossability of 30–50%, 0.81% showed high crossability more than 50%, respectively. Among the seven T. turgidum subspecies, there were significant differences in crossability. The ssp. dicoccoides and dicoccon showed the highest crossability, while polonicum the lowest. All the crossability percentages more than 30% were obtained from the crossing of ssp. dicoccoides or dicoccon with Ae. tauschii .In the second experiment, the genetics of crossability was investigated using T. turgidum ssp. durum cultivar Langdon and the D-genome disomic substitution lines of Langdon. Compared with the control Langdon, lines 7D(7A) and 4D(4B) showed higher crossability, which suggested that chromosomes 7A and 4B of tetraploid wheat cv. Langdon carried dominant alleles inhibiting crossability with Ae. tauschii . The relationships of present results with previously reported crossability genes of wheat are discussed.

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New high-molecular-weight glutenin (HMW glutenin) sequences isolated from six Psathyrostachys juncea accessions by thermal asymmetric interlaced PCR differ from previous sequences from this species. They showed novel modifications in all of the structural domains, with unique C-terminal residues, and their N-terminal lengths were the longest among the HMW glutenins reported to date. In their repetitive domains, there were three repeatable motif units: 13-residue [GYWH(/I/Y)YT(/Q)S(/T)VTSPQQ], hexapeptide (PGQGQQ), and tetrapeptide (ITVS). The 13-residue repeats were restricted to the current sequences, while the tetrapeptides were only shared by D-hordein and the current sequences. However, these sequences were not expressed as normal HMW glutenin proteins because an in-frame stop codon located in the C-termini interrupted the intact open reading frames. A phylogenetic analysis supported different origins of the P. juncea HMW glutenin sequences than that revealed by a previous study. The current sequences showed a close relationship with D-hordein but appeared to be more primitive.

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Abstract  

Positron annihilation lifetime (PAL) experiments are performed in polycarbonate (PC) exposed to CO2 and He gases as a function of time and pressure. In PC/CO2 systems, hole size and fraction reduced from PAL data increase as a function of CO2 pressure and exposure time. Significant hysteresis in positron lifetime data is observed during CO2 abasorption/desorption. In PC/He systems, no variation is observed. Hole size distribution in the CO2-exposed polymers is found to be significantly broader than in unexposed samples. The high sensitivity of PAL results to CO2 exposure of PC is thought to relate to the microstructural changes in the polymer matrix, such as penetrant plasticization, gas hydrostatic pressure effect, and molecular filling and creation of holes.

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Cereal Research Communications
Authors: S.F. Dai, D.Y. Xu, Z.J. Wen, Z.P. Song, H.X. Chen, H.Y Li, J.R. Li, L.Z. Kang, and Z.H. Yan

A novel 4.0-kb Fy was sequenced and bacterially expressed. This gene, the largest y-type HMW-GS currently reported, is 4,032-bp long and encodes a mature protein with 1,321 amino acid (AA) residues. The 4.0-kb Fy shows novel modifications in all domains. In the N-terminal, it contains only 67 AA residues, as three short peptides are absent. In the repetitive domain, the undecapeptide RYYPSVTSPQQ is completely lost and the dodecapeptide GSYYPGQTSPQQ is partially absent. A novel motif unit, PGQQ, is present in addition to the two standard motif units PGQGQQ and GYYPTSPQQ. Besides, an extra cysteine residue also occurs in the middle of this domain. The large molecular mass of the 4.0-kb Fy is mainly due to the presence of an extra-long repetitive domain with 1,279 AA residues. The novel 4.0-kb Fy gene is of interest in HMW-GS gene evolution as well as to wheat quality improvement with regard to its longest repetitive domain length and extra cysteines residues.

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