Kinetic modeling of the thermal aggregation of patatin.

A kinetic model of the thermal aggregation of patatin is presented based on chromatographic analysis of the proportions of nonaggregated and aggregated patatin. It was observed that the decrease of the amount of nonaggregated patatin proceeded initially quickly and was followed by slower aggregation at longer incubation times. It was shown that this behavior was not due to heterogeneity of the starting material. It was noted that overestimation of the amount of native molecules after a heat treatment, caused by refolding of the unfolded protein during the cooling step prior to the analysis, was significant and could not be neglected. Hence, corrections based on information on the structural properties of patatin were applied. Taking this into account, a model was proposed consisting of a first-order formation of reactive particles, followed by a second-order aggregation reaction. This model described the thermal aggregation of patatin rather accurately and was confirmed by experiments at various protein concentrations.     

Isolation and characterization of patatin isoforms.

Patatin has, so far, been considered a homogeneous group of proteins. A comparison of the isoforms in terms of structural properties or stability has not been reported. A method to obtain various isoform fractions as well as a comparison of the physicochemical properties of these pools is presented. Patatin could be separated in four isoform pools, denoted A, B, C, and D, representing 62%, 26%, 5%, and 7% of the total amount of patatin, respectively. These isoforms differed in surface charge, resulting in a different behavior on anion exchange chromatography, isoelectric focusing, native polyacrylamide gel, and capillary electrophoresis. All isoforms of the patatin family contained proteins with two molecular masses of approximately 40.3 and 41.6 kDa, respectively. The size of this difference in the molar mass (1300 Da) is on the order of one carbohydrate moiety. Despite the biochemical differences given above, no variations in the structural properties nor in the thermal conformational stability could be observed using far-ultraviolet circular dichroism, infrared, and fluorescence spectroscopy.     

Effect of heat-induced aggregation on the IgE binding of patatin (Sol t 1) is dominated by other potato proteins

The interaction of the major potato allergen patatin, Sol t 1, with IgE was investigated on a quantitative level as a function of heat treatment at different temperatures. On the basis of a number of publications, potato is considered to be a heat-labile allergen, but the molecular explanation for this behavior was not given. In this work, heat treatment of patatin in the absence and presence of other potato proteins mimicking the proteinaceous environment of the potato was studied. Using far-UV circular dichrosim spectroscopy, tryptophan fluorescence spectroscopy, and differential scanning calorimetry, the molecular transitions during heating of patatin were investigated. It was found that as long as patatin is not aggregated, denaturation of patatin on a secondary or tertiairy folding level is reversible with only a minor effect on the IgE affinity. Aggregation of patatin results in a nonreversible unfolding and a concomitant important decrease in affinity for IgE (25-fold). Aggregation of patatin in the presence of other potato proteins results in a less condensed aggregate compared to the situation of isolated patatin, resulting in a more pronounced decrease of affinity for IgE (110-fold). It is concluded that the heat lability of patatin-IgE interaction is explained by aggregation of patatin with other potato proteins rather than by denaturation of patatin itself.     

patatin启动子调控烟草液泡转化酶抑制子在马铃薯抗低温糖化中的作用

为了降低马铃薯(Solanum tuberosum )块茎低温贮藏下还原糖的积累，实验构建了马铃薯块茎特异性启动子（CIPP）调控的烟草液泡转化酶抑制子Nt-VIF基因表达载体pBICNI，并转化马铃薯植株。PCR、Northern杂交和Southern杂交分析结果显示，CIPP调控的Nt-VIF基因全长cDNA成功地导入鄂马铃薯3号（E-3）植株。14个转基因株系块茎分别贮藏在4℃和20℃条件下，贮藏1个月后进行还原糖含量和液泡酸性转化酶（VI）活性测定。结果表明，在20℃条件下转基因株系块茎还原糖（RS）含量与对照相比差异不明显，在4℃条件下RS含量则显著下降，与对照相比下降幅度从34%（株系B-13）至76.8%（株系B-1），说明Nt-VIF cDNA在马铃薯中的表达，成功地抑制了液泡酸性转化酶的活性，导致还原糖含量降低。进一步分析表明，转基因块茎低温贮藏其液泡转化酶活性与还原糖含量呈显著的正直线相关（VI = 0.3084RS + 0.0673）。实验获得的B-1、B-2、B-6、B-9、B-14等5个转基因株系，块茎低温贮藏后能直接满足炸片加工对还原糖含量的要求。     

Thermal denaturation and aggregation properties of Atlantic salmon myofibrils and myosin from white and red muscles

Thermal denaturation and aggregation abilities of salmon myofibrils and myosin were studied measuring turbidity, intrinsic fluorescence, 8-anilino-1-naphthalene sulfonic acid binding, and 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide cross-linking. The thermal behaviors of protein preparation from white and red muscles were compared, and the relationship with thermal gelation properties is discussed. The low gelation ability of salmon muscle proteins was related to a limited extent of protein denaturation and aggregation upon heating. These properties seemed to be carried by myosin molecules as a similar behavior was observed for both myofibrils and myosin preparations. The higher thermal stability observed for red muscle proteins with higher transition temperatures in rheological profiles was related to a shift to higher temperature in denaturation and aggregation processes. The extent of denaturation and aggregation was very similar for both muscle types as was the final rigidity of the gels formed.     

Thermal and water regime studied in a thin soil layer of green roof systems at early stage of pedogenesis

Purpose

The potential heat load and stormwater reduction of the anthropogenic, lightweight soil systems, such as green roofs, are valuable to heat island effect mitigation and to urban water management. Benefits of extensive green roofs, as widely used vegetated roof system with very thin soil layer, could be threatened by temporal changes of the soil structure.

Materials and methods

Green roof raised beds filled with two different anthropogenic soils (artificially constructed stripped topsoil with admixed crushed bricks and a commercial mixture of a technogenic substrate) were built to investigate the benefits of such systems in a temperate climate. These two soils were chosen with the intent to compare their thermal and water regime. One soil is expected to be favorable for hydrological functioning, whereas the other one for the thermal performance. Temperature and water balance measurements complemented with meteorological observations and knowledge of physical properties of the soil substrates provide the basis for detailed analysis of a thermal and hydrological regime in green roof raised beds. Moreover, the state of pedogenesis was studied on undisturbed soil samples by means of X-ray computed tomography.

Results and discussion

The water balance of green roof raised beds was calculated for a whole vegetation season and individual rainfall events. Runoff from raised beds was 38 and 63 % of received rainfall. On the basis of a detailed analysis of individual rainfall events, rainfall-runoff dependency was found for both raised beds. The difference between measured actual evapotranspiration and calculated potential evapotranspiration was discussed on the period with contrasting conditions in terms of moisture stress. Thermal characteristics of soil substrates result in a highly contrasting diurnal variation of soil temperatures. Analysis of X-ray computed tomography-derived macroporosity profiles reveals significant temporal changes in the soil comprised of the stripped topsoil with admixed crushed bricks.

Conclusions

Both green roof systems were able to reduce heat load of roof construction when comparing with the concrete roof construction. Similarly, received rainfall was significantly reduced. The extent of rainfall reduction mainly depends on soil, vegetation status, and experienced weather patterns. Methods used for non-invasive imaging proved to be beneficial for studying of soil structure changes.

     

Role of neck region in the thermal aggregation of myosin.

Carp dorsal myosin formed oligomers that retained ATPase activity upon heating. Cleavage of the oligomeric myosin at subfragment-1 (S-1)/rod junction released monomeric S-1 and rod, indicating that ATPase retaining myosin associated near the S-1/rod junction. The digest also contained rod oligomers. Heating a mixture of S-1 and rod generated neither ATPase retaining S-1 oligomers nor rod oligomers. Electron microscopic observation of the heated myosin revealed that some oligomers were formed by associating at the S-1/rod joining region, exhibiting a recognized double head, probably ATPase retaining oligomers. No myosin oligomers associated at the tail region were observed, thus, rod aggregation would be formed at its very restricted region near the S-1/rod junction. Based on the findings, we proposed that the neck structure is important in the thermal oligomerization process of myosin.     

Cultivar variability of patatin biochemical characteristics: table versus processing potatoes (Solanum tuberosum L.)

Biochemical characteristics of patatin proteins purified by ion-exchange and affinity chromatography from tubers of 20 potato cultivars were studied to evaluate their genotype differences with respect to utility groups, table potato cultivars (TPCs) and processing potato cultivars (PPCs). Both groups of cultivars showed similar values of protein content in dry matter (3.98-7.39%) and of patatin relative abundance (5.40-35.40%). Three mass levels (～40.6, 41.8, and 42.9 kDa) of purified patatins were found by MALDI-TOF MS within all cultivars. Differences among mass levels corresponding with the mass of sugar antenna (～1.2 kDa) confirmed the previous concept of different glycosylation extentsin patatin proteins. It was showed that the individual types of patatin varying in their masses occur in the patatin family in a ratio specific for each of the cultivars, with the lowest mass type being the major one. Electrophoretic analyses demonstrated wide cultivar variability in number of patatin forms. Especially 2D-PAGE showed 17-23 detected protein spots independently on the utility group. Specific lipid acyl hydrolase (LAH) activity of purified patatins from the individual tested cultivars varied between 0.92 and 5.46 μmol/(min mg). Patatin samples within most of the TPCs exhibited higher values of specific LAH activity than samples of PPCs. It may be supposed that individual patatin forms do not have similar physiological roles.     

反义class Ⅰ patatin基因转化马铃薯及其对试管块茎形成的影响

通过根癌农杆菌(Agrobacterium tumefaciens)介导将CaMV 35S启动子驱动的反义class Ⅰ patatin基因导入马铃薯(Solarium tuberosum)品种鄂马铃薯3号中。PCR扩增和PCR—Southern杂交证明，反义class Ⅰ patatin基因已整合到马铃薯基因组中。Northern杂交分析表明，该反义基因在转基因植株中能正常转录并导致内源classⅠ patatin mRNA含量的下降。对转基因植株试管块茎分析显示，其蛋白质含量和酯酰水解酶的活性较对照有不同程度的下降，其中下降程度最大的株系分别比对照减少36．4％和31．4％。同时部分转基因株系在组织培养条件下的结薯株率、单株结薯数和有效薯率较对照有一定程度的降低。     

Thermal degradation of sulforaphane in aqueous solution.

Sulforaphane, a cancer chemopreventive agent identified from broccoli, was degraded in an aqueous solution at 50 and 100 degrees C. The reaction mixtures were extracted with methylene chloride and analyzed by gas chromatography (GC) and gas chromatography/mass spectrometry (GC/MS). Dimethyl disulfide, S-methyl methylthiosulfinate, S-methyl methylthiosulfonate, methyl (methylthio)methyl disulfide, 1,2,4-trithiolane, 4-isothiocyanato-1-(methylthio)-1-butene, and 3-butenyl isothiocyanate were identified as volatile decomposition products. After methylene chloride extraction, the aqueous layer was dried and silica gel column chromatography was used to separate and purify the nonvolatile decomposition products. The major thermal degradation compound was determined by (1)H NMR, (13)C NMR, and FAB-MS as N, N'-di(4-methylsulfinyl)butyl thiourea. A possible mechanism for the formation of these products is proposed.     

Heat-induced aggregation of beta-lactoglobulin as a function of pH.

The effect of pH in the range 6.0-8.0 on the denaturation and aggregation of beta-lactoglobulin (beta-lg) was investigated. Results were interpreted in terms of the reaction scheme for the denaturation and aggregation of beta-lg proposed by Roefs and De Kruif (Eur. J. Biochem. 1994, 226, 883-889). The rate of conversion of native beta-lg increased strongly at higher pH values, whereas the molecular mass of the aggregates decreased strongly. In the pH range 6.4-8.0 aggregates were formed mainly by intermolecular disulfide bonds, but even at pH 6.0, thiol/disulfide exchange reactions were involved, although to a lesser extent. The time course of the exposure of the thiol group in native beta-lg upon heating and the subsequent disappearance of this group through the formation of disulfide-linked aggregates was investigated by reaction with 5,5'-dithiobis(2-nitrobenzoic acid) and varied strongly with pH. These observations could be used, in combination with the reaction steps of the reaction scheme, to describe qualitatively the strongly pH-dependent isothermal calorimetry curves, measured at 65 degrees C.     

Sulfur retention at intensively studied sites in the U.S. and Canada

We compiled and summarized current literature on S input/output budgets for intensively studied sites and soil plots in the U.S. and Canada and found S retention to be related to both soil order and extent of the last glaciation (Wisconsinan). Zero net retention is associated with Spodosols and was found only at sites north of the limit of Wisconsinan glaciation. Sites south of the limit of glaciation appear to be retaining from 20 to 90% of incoming S. These findings support the hypothesis that there exist regional variations in S retention in North America. Such variations are important in determining and predicting effects of acidic deposition on surface water chemistry.     

Calcium- and magnesium-dependent aggregation of legume seed storage proteins.

The solubility characteristics and sedimentation behavior of total or individual globulins from legume seeds [Lupinus albus L., Pisum sativum L., and Glycine max (L.) Merr.] were investigated. The typical insolubility of globulins detected during their extraction seems to be due to the presence of a low molecular weight factor(s) in the seed extract. The solubility of the purified globulins decreases with increasing concentrations of calcium and/or magnesium, but not of other cations, showing minimum values at concentrations that vary with the particular globulin considered. Ultracentrifugation analyses revealed that the Ca(2+)- and/or Mg(2+)-induced insolubilization of the globulins involves the formation of high-order aggregates of molecules of the same or of different globulins. These macromolecular structures are dissociated under conditions of high ionic strength, suggesting the involvement of electrostatic interactions in the aggregation process. The degree of association relies heavily on the amount of Ca(2+) and/or Mg(2+) available, on the presence of chelating agents for these divalent cations, and on the ionic strength of the surrounding medium. The possible physiological significance of the findings is discussed.     

安徽宣城样区土系的划分

本文根据样区岗坡地第四纪红土、下蜀黄土与沟谷地黄土性堆积物母质所发育的土壤 ,确立了 12个特征土层 ,并以特征土层的种类、排列及性状 ,进行了土系的具体划分     

Determination of coumaphos and its oxygen analog in eggs by in situ fluorometry.

A method is reported for the simultaneous determination of coumaphos (o,o-diethyl o(3-chloro-4-methyl-2-oxo-2H-1-benzopyran-7-yl)phosphorothioate) and its oxygen analog, Coroxon, in eggs in the ppb range. The residues are extracted with acetone and chloroform. The extract is purified by liquid-liquid partition followed by column chromatography and then by 2-dimensional thin layer chromatography. The fluorescence is measured directly on the chromatogram.     

浙江衢县样区土系的划分

本文根据中国土壤系统分类中基层分类课题研究的要求 ,探讨了浙江衢县样区土划分的原则和依据 ,对样区的土系作了具体的划分     

Poorly ordered hydrous Fe oxides, colloidal dispersion and soil aggregation. II. Modification of silty soil aggregation with Fe(III) polycations and model humic macromolecules

Poorly ordered ferrihydrites, more or less associated with synthetic humic macro-molecules, were added to a poorly structured temperate silty soil. Manipulation of the net soil charge through these additions was measured by potentiometric titration and cation exchange capacity. The consequences of anchoring positively charged Fe hydrous oxides on negative permanent clay surface charges were studied. Both cementation and aggregate water-stability increased with increase in adsorbed iron. The aggregation process was studied by using micromorphology and ultramicromorphology, water retention curves, mercury porosimetry and a fractal approach. Aggregate water-stability was studied when the soils were air-dried, with some irreversible aggregation, and oven-dried or wetted from – 1.5 MPa to – 1 kPa thereafter. Soils with added Fe(III) polycation–humic macro-molecule associations were less positively charged, less cemented and less stable than soils amended with Fe(III) polycations alone. The effect of these treatments on slaking is discussed.     

Chemical derivatization analysis of pesticide residues. VIII. Analysis of 15 chlorophenols in natural water by in situ acetylation

A rapid analytical method is presented for quantitative analysis of 15 chlorophenols in natural waters by in situ acetylation. In the presence of KHCO3, phenols in water are acetylated by acetic anhydride directly without pre-extraction. The resultant acetates are extracted by petroleum ether and analyzed by electron capture gas chromatography. The investigation to optimize the conditions for in situ acetylation of these phenols is also described. This method has been validated and shown to be applicable over a range from 100 to 0.01 ppb with a 1 L water sample.     

Microbial aggregation of sand in an embryo dune system

The importance of microorganisms in the aggregation of sand in an embryo dune system was examined. Of three main types of aggregates formed, microbial aggregates were found to be more important at stabilizing sand than either root-microbial or debris-microbial aggregates on the beach and at the edge of the dune but roots and their associated microorganisms were more important on the hummock of the dune. The amount of microbial and root-microbial aggregated sand was higher during the winter when the vegetation was dying down and decaying. In the absence of roots, microorganisms, in particular bacteria, play a major role in aggregating sand. The bacteria are well adapted to the unfavourable habitat of the beach as they are motile and tolerant to sea water, being able to grow in a salinity of 3.5%. Bacteria may play a major role in aggregating and stabilizing sand prior to colonization by higher plants.