Atypical Ubiquitination and Parkinson’s Disease

Ubiquitination (the covalent attachment of ubiquitin molecules to target proteins) is one of the main post-translational modifications of proteins. Historically, the type of polyubiquitination, which involves K48 lysine residues of the monomeric ubiquitin, was the first studied type of ubiquitination. It usually targets proteins for their subsequent proteasomal degradation. All the other types of ubiquitination, including monoubiquitination; multi-monoubiquitination; and polyubiquitination involving lysine residues K6, K11, K27, K29, K33, and K63 and N-terminal methionine, were defined as atypical ubiquitination (AU). Good evidence now exists that AUs, participating in the regulation of various cellular processes, are crucial for the development of Parkinson’s disease (PD). These AUs target various proteins involved in PD pathogenesis. The K6-, K27-, K29-, and K33-linked polyubiquitination of alpha-synuclein, the main component of Lewy bodies, and DJ-1 (another PD-associated protein) is involved in the formation of insoluble aggregates. Multifunctional protein kinase LRRK2 essential for PD is subjected to K63- and K27-linked ubiquitination. Mitophagy mediated by the ubiquitin ligase parkin is accompanied by K63-linked autoubiquitination of parkin itself and monoubiquitination and polyubiquitination of mitochondrial proteins with the formation of both classical K48-linked ubiquitin chains and atypical K6-, K11-, K27-, and K63-linked polyubiquitin chains. The ubiquitin-specific proteases USP30, USP33, USP8, and USP15, removing predominantly K6-, K11-, and K63-linked ubiquitin conjugates, antagonize parkin-mediated mitophagy.     

Keratin 7 Is a Constituent of the Keratin Network in Mouse Pancreatic Islets and Is Upregulated in Experimental Diabetes

Keratin (K) 7 is an intermediate filament protein expressed in ducts and glands of simple epithelial organs and in urothelial tissues. In the pancreas, K7 is expressed in exocrine ducts, and apico-laterally in acinar cells. Here, we report K7 expression with K8 and K18 in the endocrine islets of Langerhans in mice. K7 filament formation in islet and MIN6 β-cells is dependent on the presence and levels of K18. K18-knockout (K18^‒/‒) mice have undetectable islet K7 and K8 proteins, while K7 and K18 are downregulated in K8^‒/‒ islets. K7, akin to F-actin, is concentrated at the apical vertex of β-cells in wild-type mice and along the lateral membrane, in addition to forming a fine cytoplasmic network. In K8^‒/‒ β-cells, apical K7 remains, but lateral keratin bundles are displaced and cytoplasmic filaments are scarce. Islet K7, rather than K8, is increased in K18 over-expressing mice and the K18-R90C mutation disrupts K7 filaments in mouse β-cells and in MIN6 cells. Notably, islet K7 filament networks significantly increase and expand in the perinuclear regions when examined in the streptozotocin diabetes model. Hence, K7 represents a significant component of the murine islet keratin network and becomes markedly upregulated during experimental diabetes.     

Estimating the potential to reduce potassium surplus in intensive vegetable fields of China

Potassium (K) is important for crop quality, and this knowledge has stimulated substantial K fertilizer application in intensive cropping systems of China, resulting in an unbalanced nutrient supply and the squandering of K resources. In this study, we assessed the status of K in China’s intensive vegetable planting systems using data from the literature and our recent results. Scenario analysis was designed to estimate the potential for reducing chemical K fertilizer based on the K recommended strategy and manure replacement strategies. The results showed that K surplus, and soil exchangeable K levels in vegetable fields increased during the period with a stable growing area (2003–) compared to the period with an expanding growing area (before 2003). Much higher K surplus and accumulation and more severe K leaching were observed in greenhouse. Excessive K application contributed to low K use efficiency and K resource waste. Based on the data analysis, the K consumption derived from chemical fertilizer and organic amendments was 8.2 million Mg K, though the theoretical demand for vegetable planting was only 6.0 million Mg K with the K recommendation strategy of “build-up and maintenance (B&M)”. Scenario analysis suggested that chemical K fertilizer application could be reduced by 21.7, 69.6 and 54.3% by considering alternative K sources derived from manure and straw, as based on the conventional proportion, N-based strategy and P-based strategy, respectively. Maximizing the use of K from organic amendments requires limiting manure application by considering environmental deterioration and the topdressing requirement with chemical K fertilizer.     

烘焙生物质燃烧过程中钾的赋存形态及析出迁移特性

选取稻秆和棉秆为原料,在烘焙预处理后,通过固定床燃烧实验结合HSC Chemistry热力学平衡计算,获得了烘焙生物质燃烧过程中碱金属K的析出和迁移规律。结果表明：烘焙过程中存在着少量水溶性K的释放及其向醋酸铵溶态K的转化,而其转化和释放能力与Cl/K呈正相关。烘焙生物质的成灰率随着燃烧温度的升高而下降,而K的释放率随温度的变化则相反,其主要释放形式为K的氯化物和KOH;此外,600℃时,水溶性K和醋酸铵溶态K主要转化为char-K,700~900℃时其主要转化为K的硅酸盐,随着温度的上升,其转化量不断增加。相比于原生生物质,烘焙生物质有更高的成灰率;此外,烘焙促进了生物质燃烧过程中醋酸铵溶态K向酸溶态或残渣态K转化,同时抑制了水溶性K的释放,这些使得烘焙生物质燃烧过程中K的释放率更低,而烘焙对生物质燃烧过程中K释放的抑制与烘焙过程中Cl的释放率呈正相关。     

Keratin 8/18 Regulate the Akt Signaling Pathway

Keratin 8 and keratin 18 (K8/K18) are intermediate filament proteins that form the obligate heteropolymers in hepatocytes and protect the liver against toxins. The mechanisms of protection include the regulation of signaling pathway associated with cell survival. Previous studies show K8/K18 binding with Akt, which is a well-known protein kinase involved in the cell survival signaling pathway. However, the role of K8/K18 in the Akt signaling pathway is unclear. In this study, we found that K8/K18-Akt binding is downregulated by K8/K18 phosphorylation, specifically phosphorylation of K18 ser7/34/53 residues, whereas the binding is upregulated by K8 gly-62-cys mutation. K8/K18 expression in cultured cell system tends to enhance the stability of the Akt protein. A comparison of the Akt signaling pathway in a mouse system with liver damage shows that the pathway is downregulated in K18-null mice compared with nontransgenic mice. K18-null mice with Fas-induced liver damage show enhanced apoptosis combined with the downregulation of the Akt signaling pathway, i.e., lower phosphorylation levels of GSK3β and NFκB, which are the downstream signaling factors in the Akt signaling pathway, in K18-null mice compared with the control mice. Our study indicates that K8/K18 expression protects mice from liver damage by participating in enhancing the Akt signaling pathway.     

河西走廊灌漠土钾素状况及施钾效应

多点调查表明 ,河西灌漠土全钾、速效钾比 70年代末平均降低了 2 2 %和 4 1.2 % ,耕层全钾、缓效钾、速效钾平均含量分别为 1.4 2 %、10 34mg/kg和 14 2 mg/kg。带田作物及小麦、玉米、甜菜、马铃薯单作 ,当季施钾均无明显增产效应。当土壤速效钾为 70 mg/kg以下时 ,春小麦、玉米、施钾显效 ;缓效钾为 70 0 mg/kg以下、速效钾 12 0mg/kg以下时 ,带田作物施钾显效。     

Genotypic variation for potassium uptake and utilization efficiency in wheat

Pot and field experiments were carried out in order to study the genotypic variation in potassium uptake and utilization by winter wheat (T. aestivum L). Fifty-eight genotypes showed variation in K concentration, accumulation and potassium efficiency ratio (KER) in a field experiment. KER had significant positive correlation with grain weight per spike and harvest index (HI), and significantly negative correlation with stem K concentration at maturity. In a subsequent field experiment, three out of four genotypes, Yunmei 5, 94-18 and 94-6 differed in their KER, and had significantly higher grain yield with K application (K1) than without K application (K0). The 4th genotype Zhemei 1 showed no response to K. The yield increase due to K application was mainly due to the improvement in spike development from tillers. K concentration and accumulation in the plant varied between genotypes, K levels and plant parts. Among various plant parts, stem contained the highest K concentration and had the highest K accumulation at maturity, and changed considerably with the K level, while other plant parts remained relatively unchanged. All four genotypes had smaller KER in K1, as compared to K0, but there existed some difference in KER reduction among genotypes.     

Fertilizer inputs, nutrient balance, and soil nutrient-supplying power in intensive, irrigated rice systems. II: Effective soil K-supplying capacity

Based on the analysis of soil K status in 11 long-term fertility experiments in Asia, two approaches for assessing the K-supplying power of lowland paddy soils were evaluated to predict total K uptake by irrigated rice. A regression model combining commonly used static soil test parameters that appeared to integrate measures of K release from nonexchangeable forms as well as chemical factors affecting K activity in soil solution explained 72% of the crop K uptake in NP and NPK treatments. However, this approach would require determination of six soil properties and it does not provide a direct measure of K release dynamics. The second approach used mixed-bed ion exchange resin capsules to measure K release during 2-wk anaerobic incubation. The resin method provided an integrative measure of soil K status and the factors controlling K transformation and diffusion rates, which are embodied in two kinetic parameters describing the dynamics of rapid- and slow-phase K release. The resin method was sensitive to past fertilizer history and the resulting buildup or depletion of soil K reserves and it was a better predictor of total K uptake in the NP and NPK plots (r²=0.82) than static soil tests. The results also indicated that high (Ca+Mg)/K ratios may contribute to K deficiency in rice soils.     

高压下二氧化碳与正辛烷,正壬烷二元系汽液相平衡

高压下二氧化碳与正辛烷、正壬烷二元系汽液相平衡云志，史美仁，时钧（南京化工大学化工系，南京２１０００９）关键词相平衡，二氧化碳，正辛烷，正壬烷１前言对于高压下的二氧化碳－烃类体系，人们已经做了不少相平衡的测定与研究工作，其中尤以含六个碳以下的烃类体系...     

The position of the structurally autonomous kringle 2 domain influences the functional features of tissue-type plasminogen activator

Tissue-type plasminogen activator (t-PA) is composed of structurallyautonomous domains. From the N-terminus of t-PA, a finger-likedomain (F), an epidermal growth factor-like domain (G), twokringle domains (Kl and K2) and a serine protease domain (P)can be discerned. The K2 domain of t-PA is known to be involvedin lysine binding, fibrin binding and fibrin-dependent plasminogenactivation. To study the functional autonomy of the K2 domainin t-PA we constructed, with the aid of a cassette t-PA gene[Rehberg et al. (1989) Protein Engng, 2,371–377], mutantt-PA genes coding for four molecules (FGK1K2P, FGK2K1P, GK1K2Pand GK2K1P) in which the K2 domain was placed in two differentpositions in t-PA. The DNAs of wild-type t-PA and the t-PA variantswere expressed in Chinese hamster ovary cells and the recombinantproteins were purified by affinity chromatography.All moleculeswere expressed in their single-chain form and could be convertedto their two-chain form. With these molecules, lysine binding,fibrin binding and fibrin-dependent plasminogen activation werestudied. All variants showed affinity for lysyl-Sepharose andaminohexyl-Sepharose. Reversal of the K domains (FGK2K1P versusFGK2K1P and GK1K2P versus GK2K1P) resulted in a 23–47%weaker interaction to both lysyl-Sepharose and aminohexyl-Sepharose.Deleting the F domain (FGK1K2P versus GK1K2P and FGK2K1P versusGK2K1P) resulted in a 20–70% improvement of the interactionslysyl-Sepharose and aminohexyl-Sepharose. All variants boundto a forming fibrin clot. Reversal of the K domains (FGK1K2Pversus FGK2K1P) reduced fibrin binding. In the presence of thelysine analogue -amino caproic acid, only FGK1K2P bound to fibrin.All variants activated plasminogen. In the absence of fibrinogenCNBr fragments (mimic of fibrin), the reversal of the K domain(FGK2K1P) resulted in a 2-fold improved plasminogen activation.In the presence of a fibrin mimic, the plasminogen activationsof the F domain deletion analogues GK1K2P and GK2K1P were foundto be decreased 2- to 4-fold. From these results we concludedthat the function of t-PA in lysine binding, fibrin bindingand fibrin-dependent plasminogen activation is dependent onthe correct spatial orientation of the K2 domain within thet-PA molecule     

Potassium uptake and requirement in organic grassland farming

Use of mineral fertilizers is restricted in organic farming. The aim of the present paper was therefore to study whether potassium (K) limits yields in Norwegian organic grasslands. The K status in soil and herbage on 26 organic farms was investigated, and the response to K application in six fertilization experiments was explored. Further, the relationship between soil K analyses and K release from soil was examined. K application to grassland on the investigated farms was generally low, giving negative field K balances on 23 of the farms. The soils were classified as low or intermediate in readily available K (K_AL) on 23 of the farms. The mean K concentration for herbage samples from the first cut on these farms was 18.0 g K kg⁻¹ dry matter. In fertilization experiments, K application increased the K concentration in herbage. However, there was no significant effect on yield, even when K concentration in herbage on plots without K application was low. The lack of significant yield response to K application can be explained by low amounts of crop-available nitrogen (N). There was a tendency for increased plant uptake from reserve K with increasing values of acid soluble K (K–HNO₃) in soil. Separate K analyses of timothy (Phleum pratense) and red clover (Trifolium pratense) revealed that red clover showed better competitiveness for K than timothy in leys where N supply was limited.     

Long-term potash application and wheat straw return reduced soil potassium fixation and affected crop yields in North China

In light of China’s mineral potassium (K) deficit, it is imperative to improve K fertilizer use efficiency and conserve soil K. This study explored the effects of 15 years (1993–2007) of continuous potash application and wheat straw return on the K fixation capacity of cultivated soils in North China. Soil was collected from a number of long-term test sites, with different rates of potash application and wheat straw return and under different cropping systems. The results showed that long-term continuous potash application and straw return significantly reduced soil K fixation capacity. In addition, soil K fixation increased with the K concentration of the treatment solution. Soil K fixation levels were higher under double cropping systems than for single cropping systems. Soil K fixation capacity showed a clear zonal distribution pattern across North China; the soil K fixation capacity gradually increased from west to east. When the K concentration of the treatment solution was 1000 mg L^?1, the average K fixation of soils fertilized only with N and P at experimental sites from Northwest, North-central and Northeast China were 359, 443, and 469 mg kg^?1, respectively. The pattern of soil K fixation capacity across the different regions of North China matched the pattern of the timing of significant yield responses to K applications in the different regions. This research suggests that there should be a requirement for straw return as well as K fertilization to optimise K supply to crops during production.     

Fertilizer inputs, nutrient balance, and soil nutrient-supplying power in intensive, irrigated rice systems. I. Potassium uptake and K balance

Research in many countries indicates a negative K balance in intensive, irrigated rice systems but comparative studies across different environments are few. Using a uniform sampling methodology, we measured K uptake, K use efficiency, and K balance in six different fertilizer treatments of long-term fertility experiments with rice at 11 sites in five Asian countries. Depending on the absolute yield level, K uptake requirements of rice ranged from 17 to 30 kg K per ton of grain. For yields greater than 8 t ha^-1, total K uptake exceeded 200 kg ha^-1. The K balance at most experimental sites was negative, with an average net removal of 34–63 kg K season^-1. There was significant depletion of soil K reserves at many sites. Based on these data, we estimated that the amount of K cycled annually from the soil into rice plants is 7–10 million t in irrigated rice systems of Asia. About 1 million t of this total amount is removed with the harvested grain. Present recommendations for K addition in most intensive irrigated rice domains are insufficient to replace K removal. However, response to K can only be expected on soils with deficient supply capacity and where other nutrients, particularly N and P, are not limiting. Efficient K management for rice must therefore be based on the K input/output balance, the achievable yield target, and the effective K-supplying power of the soil.     

A Proteomic Strategy for Quantifying Polyubiquitin Chain Topologies

We present a method to probe the structure of polyubiquitin (polyUb) chains by mass spectrometry. As polyUb chains can be linked by any of seven lysine residues in the sequence of ubiquitin, the structural diversity of the chains could be enormous (e.g., as many as 70 configurations for tri-Ub). To quantify the frequency of every lysine linkage, polyUb chains were digested by trypsin and analyzed by tandem mass spectrometry using synthetic isotope-labeled peptides as internal standards. Employing a purified ubiquitin dimer to optimize conditions for trypsinization, we found that all tryptic sites except K33 could be reliably cleaved under insolution and in-gel conditions. Because K33 miscleavage led to large underestimation of K29 linkage, its digestion efficiency was calculated to correct the measurement. The reverse-phase chromatography was also adjusted to capture the small hydrophilic peptide of K29 linkage. In addition, the analysis of the K6-linkage peptide was complicated by methionine oxidation and therefore the sample was treated with hydrogen peroxide to fully oxidize methionine to sulfoxide. While the method was sensitive enough to detect K48 and K63 linkages directly from total yeast extract, all linkages were quantified from pre-enriched Ub-conjugates, revealing that the concentration ratio of K6:K11:K27:K29:K33:K48:K63 was ˜40:120:20:15:5:100:40 in yeast during the log growth phase, and the sum of non-K48 linkages was more than twice as abundant as the canonical K48 linkage. Moreover, increasing the concentration of ubiquitin in yeast raised the level of almost all linkages. Inhibiting proteasome activity augmented only K48- and K29-linked chains, recapitulating their roles in proteolysis and suggesting non-proteolytic functions of other linkages in vivo.     

钢纤维高强混凝土断裂韧度及影响因素

通过钢纤维高强混凝土切口梁三点弯曲试验,探讨了相对切口深度（a0/h）、粗骨料最大粒径（dmax）、水灰比（W/C）和钢纤维体积率（ρf）等因素对钢纤维高强混凝土断裂韧度（KfIC）和断裂韧度增益比（KfIC/KIC）的影响。结果表明：ρf一定时,KfIC随a0/h的增加逐渐减小,随dmax的增加呈增大趋势,随W/C的减小逐渐增加;a0/h一定时,KfIC随ρf的增加逐渐增大;钢纤维能够显著提高高强混凝土断裂韧度,KfIC/KIC大于1;影响因素不同,KfIC/KIC变化趋势不同。在分析试验结果的基础上,建立了钢纤维高强混凝土断裂韧度计算模式。     

PVP、VP/VA共聚物整发定型效果研究

研究了PVP K30、K90和VA64在整发定型中的定型效果。实验表明,在中等湿度下（RH60%）,K30浓度3%～5%能达到中等定型强度,浓度7%～9%时方能达到较强的定型强度,VA64和K90单独使用时,浓度3%即可达到较强的定型强度;高湿度下（RH90%）,K90表现较为优异,VA64次之,K30随浓度的提高对定型强度并无显著改善。在K30、K90、VA64复配实验中发现,中等湿度下三者对卷曲保持贡献相似,可灵活选择,以降低成本。高湿度下,配方中K90的含量对卷曲保持效果影响显著,应以K90为主,VA64、K30为辅。     

Monitoring the changes in soil potassium by extraction procedures and electroultrafiltration (EUF) in a Tropaquept under twenty years of rice-rice cropping

Chemical extraction procedures and electroultrafiltration (EUF) fractions were evaluated for measuring the changes in soil K in a Tropaquept as a consequence of continuous fertilizer use and rice-rice cropping for 20 years in a long-term fertilizer experiment. During the course of 20 years the gap in total K uptake by crops in treatments receiving K and those without an external K supply widened, indicating a stress on soil K reserves in the latter treatments. Readily available forms, i.e. water-soluble, 0.01 MCaCl₂, citric acid and ammonium acetate extractable K did not undergo much change. On the contrary, there was a conspicuous decrease in strongly held 3 M H₂SO₄ and 1 M boiling HNO₃ K (nonexchangeable K), as these forms replenished the soil solution K removed by the crop plants. Similarly, considerable decrease was noticed in EUF 30–35 K obtained at higher temperature and voltage, as it also represents nonexchangeable K in soils. NPK and NPK plus FYM arrested, to a greater extent, the depletion in soil K. Huge K removals, from 1000 to 3550 kg K ha^-1, by the rice crop in 20 years were not reflected in NH₄OAc K which is commonly used as a criterion for fertilizer K recommendations by the soil testing laboratories in India. The total K uptake by the rice crop during 20 years corresponded closely to the changes in nonexchangeable K as measured by 3 M H₂SO₄ and 1 M HNO₃. This suggests the need for including nonexchangeable K in soil test calibration for better K fertilizer recommendations in long-term operations.     

Morphology and mechanical properties of polyamide‐6/K resin blends

Mechanical properties and morphological studies of compatibilized blends of polyamide‐6 (PA‐6)/K resin grafted with maleic anhydride (K‐g‐MAH) and PA‐6/K resin/K‐g‐MAH were investigated as functions of K resin/K‐g‐MAH and dispersed phase K resin concentrations, and all the blends were prepared using twin screw extruder followed by injection molding. Scanning electron microscopy (SEM) were used to assess the fracture surface morphology and the dispersion of the K resin in PA‐6 continuous phase, the results showing extensive deformation in presence of K‐g‐MAH, whereas, uncompatibilized PA‐6/K resin blends show dislodging of K resin domains from the PA‐6 matrix. Dynamic mechanical thermal analysis (DMTA) test reveals the partially miscibility of PA‐6 with K‐g‐MAH, and differential scanning calorimetry (DSC) results further identified that the introduction of K‐g‐MAH greatly improved the miscibility between PA‐6 and K resin. The mechanical properties of PA‐6/K resin blends and K‐g‐MAH were studied through bending, tensile, and impact properties. The Izod notch impact strength of PA‐6/K‐g‐MAH blends increase with the addition of K‐g‐MAH, when the K‐g‐MAH content adds up to 20 wt %, the impact strength is as more than 6.2 times as pure PA‐6, and accompanied with small decrease in the tensile and bending strength less than 12.9% and 17.5%, respectively. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Fracture toughness evaluation of K resin® grafted with maleic anhydride‐ compatibilized polyamide 6/K resin® blends

The mechanical behavior and fracture toughness of polyamide 6 (PA6)/K resin^® (K) blends, with and without maleic anhydride‐grafted K resin^® (K‐g‐MAH) incorporated, have been investigated. The results showed that the tensile strength, elongation at break and impact strength of PA6/K blends were improved considerably on incorporating K‐g‐MAH. This results from the improvement of compatibility between the PA6 and K phases. The essential work of fracture (EWF) method was employed to determine the fracture toughness of PA6/K blends with and without K‐g‐MAH incorporated. The effect of composition on the EWF parameters of the blends was particularly investigated. The results showed that a significant improvement in the specific EWF (w_e) of PA6/K blends occurred when K‐g‐MAH was incorporated. The effect of K‐g‐MAH content on the fracture toughness of the PA6/K/K‐g‐MAH blends was mainly achieved through its influence on the specific essential and nonessential work of fracture in the yielding process. Copyright © 2007 Society of Chemical Industry     

Provincial potassium balance of farmland in China between 1980 and 2010

Great changes have been happened over the past 30 years in chemical fertilizer input in China, and thus a gross potassium (K) budget model established to evaluate the variation of farmland K balance for China in 1980 and 2010 at the national scale is important. Results indicated that total K input in 1980 was 6.8 million tonnes, in which chemical fertilizer, organic manure and other sources accounted for 5.6, 77.5 and 16.9% respectively. Total K input in 2010 was 21.6 million tonnes, in which chemical fertilizer, organic manure and other sources accounted for 43.5, 50.4 and 6.1% respectively. Total K output in 1980 was 8.1 million tonnes, in which crops removal and loss accounted for 98.2 and 1.8% respectively. Total K output in 2010 was 19.1 million tonnes, in which crops removal and loss accounted for 99.2 and 0.8%, respectively. Similar to K input, the spatial distribution of K output differed greatly. Total K deficit was 1.3 million tonnes, and the range of K balance in each province was ?86.7 to 53.6 kg K₂O ha^?1 in 1980. Compared with that, total K surplus was 2.5 million tonnes and the range of K balance in each province was ?43.0 to 256.6 kg K₂O ha^?1 in 2010. Chemical fertilizer K application over the past 30 years makes the great changes in average K balance from deficit to surplus in general; however, the great spatial variation in K balance drives urgent need for site-specific K nutrient management.