Low Molecular Weight, 4-O-Sulfation,and Sulfation at Meta-Fucose Positively Promote the Activities of Sea Cucumber Fucoidans on Improving Insulin Resistance in HFD-Fed Mice

Fucoidans from sea cucumber (SC-FUC) have been proven to alleviate insulin resistance in several species. However, there are few studies that clarify the relationship between their structure and bioactivity. The present study evaluated the influence of molecular weight (Mw), sulfation concentrations (Cs), and sulfation position on improving insulin resistance using SC-FUC. Results showed that fucoidans with lower Mw exerted stronger effects. Having a similar Mw, Acaudina molpadioides fucoidans (Am-FUC) with lower Cs and Holothuria tubulosa fucoidans with higher Cs showed similar activities. However, Isostichopus badionotus fucoidans (higher Cs) activity was superior to that of low-Mw Thelenota ananas fucoidans (Ta-LFUC, lower Cs). Eliminating the effects of Mw and Cs, the bioactivity of Am-FUC with sulfation at meta-fucose exceeded that of Ta-FUC with sulfation at ortho-position. Moreover, the effects of Pearsonothuria graeffei fucoidans with 4-O-sulfation were superior to those of Am-LFUC with 2-O-sulfation. These data indicate that low Mw, 4-O-sulfation, and sulfation at meta-fucose contributed considerably to insulin resistance alleviation by SC-FUC, which could accelerate the development of SC-FUC as a potential food supplement to alleviate insulin resistance.     

Antidiabetic Activity of Differently Regioselective Chitosan Sulfates in Alloxan-Induced Diabetic Rats

The present study investigated and compared the hypoglycemic activity of differently regioselective chitosan sulfates in alloxan-induced diabetic rats. Compared with the normal control rats, significantly higher blood glucose levels were observed in the alloxan-induced diabetic rats. The differently regioselective chitosan sulfates exhibited hypoglycemic activities at different doses and intervals, especially 3-O-sulfochitosan (3-S). The major results are as follows. First, 3,6-di-O-sulfochitosan and 3-O-sulfochitosan exhibited more significant hypoglycemic activities than 2-N-3, 6-di-O-sulfochitosan and 6-O-sulfochitosan. Moreover, 3-S-treated rats showed a more significant reduction of blood glucose levels than those treated by 3,6-di-O-sulfochitosan. These results indicated that –OSO₃⁻ at the C3-position of chitosan is a key active site. Second, 3-S significantly reduced the blood glucose levels and regulated the glucose tolerance effect in the experimental rats. Third, treatment with 3-S significantly increased the plasma insulin levels in the experimental diabetic rats. A noticeable hypoglycemic activity of 3-S in the alloxan-induced diabetic rats was shown. Clinical trials are required in the future to confirm the utility of 3-S.     

Immunostimulative Activity of Low Molecular Weight Chitosans in RAW264.7 Macrophages

Chitosan and its derivatives such as low molecular weight chitosans (LMWCs) have been reported to exert many biological activities, such as antioxidant and antitumor effects. However, complex and molecular weight dependent effects of chitosan remain controversial and the mechanisms that mediate these complex effects are still poorly defined. This study was carried out to investigate the immunostimulative effect of different molecular weight chitosan in RAW264.7 macrophages. Our data suggested that two LMWCs (molecular weight of 3 kDa and 50 kDa) both possessed immunostimulative activity, which was dependent on dose and, at the higher doses, also on the molecular weight. LMWCs could significantly enhance the the pinocytic activity, and induce the production of tumor necrosis factor α (TNF-α), interleukin 6 (IL-6), interferon-γ (IFN-γ), nitric oxide (NO) and inducible nitric oxide synthase (iNOS) in a molecular weight and concentration-dependent manner. LMWCs were further showed to promote the expression of the genes including iNOS, TNF-α. Taken together, our findings suggested that LMWCs elicited significantly immunomodulatory response through up-regulating mRNA expression of proinflammatory cytokines and activated RAW264.7 macrophage in a molecular weight- and concentration-dependent manner.     

Chitosan/Alginate Nanoparticles for the Enhanced Oral Antithrombotic Activity of Clam Heparinoid from the Clam Coelomactra antiquata

Chitosan/alginate nanoparticles (DG1-NPs and DG1/Cur-NPs) aiming to enhance the oral antithrombotic activity of clam heparinoid DG1 were prepared by ionotropic pre-gelation. The influence of parameters, such as the concentration of sodium alginate (SA), chitosan (CTS), CaCl₂, clam heparinoid DG1, and curcumin (Cur), on the characteristics of the nanoparticles, were investigated. Results indicate that chitosan and alginate can be used as polymer matrices to encapsulate DG1, and nanoparticle characteristics depend on the preparation parameters. Nano-particles should be prepared using 0.6 mg/mL SA, 0.33 mg/mL CaCl₂, 0.6 mg/mL CTS, 7.2 mg/mL DG1, and 0.24 mg/mL Cur under vigorous stirring to produce DG1-NPS and DG1/Cur-NPS with small size, high encapsulation efficiency, high loading capacity, and negative zeta potential from approximately −20 to 30 mV. Data from scanning electron microscopy, Fourier-transform infrared spectrometry, and differential scanning calorimetry analyses showed no chemical reaction between DG1, Cur, and the polymers; only physical mixing. Moreover, the drug was loaded in the amorphous phase within the nanoparticle matrix. In the acute pulmonary embolism murine model, DG1-NPs enhanced the oral antithrombotic activity of DG1, but DG1/Cur-NPs did not exhibit higher antithrombotic activity than DG1-NPs. Therefore, the chitosan/alginate nanoparticles enhanced the oral antithrombotic activity of DG1, but curcumin did not further enhance this effect.     

小麦低分子量谷蛋白亚基品质效应的研究

为了在小麦品质遗传改良中更好地利用低分子量麦谷蛋白亚基(LMW-GS)的品质效应,以35个小麦品种为材料,对17种LMW-GS的品质效应进行了研究.结果表明,在 Glu-A3位点,对面筋数量的正向效应为A3c、A3b、A3d、A3e＞A3a,对面筋强度的正向效应为A3c＞A3b、A3d＞A3a、A3e.在Glu-B3位点,对面筋数量的正向效应为B3i、B3d＞B3f＞B3e、B3h＞B3g＞B3j,对面筋强度的正向效应为B3d＞B3h＞B3j、B3e＞B3i、B3f＞B3g.在Glu-D3位点,对面筋数量的正向效应为D3e＞D3c＞D3d＞D3b、D3a,对面筋强度的正向效应为D3a＞D3c、D3e＞D3b、D3d.综合各个亚基的品质效应,本研究提出了包含17种小麦LMW-GS的评分体系,品种品质类型与LMW-GS的对应分析结果验证了LMW-GS品质效应的分析结果.研究结果还表明,不同位点优异LMW-GS的品质效应具有累加作用.     

小麦低分子量谷蛋白一级结构分析

用数学统计方法和蛋白质序列分析软件对部分已测序的17种低分子量走谷蛋白亚基含氮量、氨基酸含量及一级结构序列进行比较分析。以期从氨基酸层次上揭示其结构和功能及进化上的关系．结果表明：(1)其平均含氮量为17．8％;(2)氨基酸含量基本恒定。以谷氨酰胺的含量最多。且常连接在一起;(3)存在119个保守性氨基酸残基扣两个保守性片段。一个是“QQQ-PPFSQQ”。一个是“IP-VHPSILQQLNPCKVFLQQ—C—P—AM-Q-LARSQM-QS-CHVMQQQCCQQL—QIPQQSRYEAI-AI-YSIILQEQQ”(“-”表示各序列中不同的氨基酸);(4)X84960、X84961、Y14104;X13306、U86025、U86027、U86029两组亚基序列中各具有一定程度的同源性。     

In Vitro and In Vivo Dendritic Cell Immune Stimulation Effect of Low Molecular Weight Fucoidan from New Zealand Undaria pinnatifida

Low molecular weight fucoidan (LMWF) has been reported to have immunomodulation effects through the increase of the activation and function of macrophages. In this study, the regulating effect of LMWF from Undaria pinnatifida grown in New Zealand on dendritic cells (DCs) was investigated. We discovered that LMWF could stimulate DCs’ maturation and migration, as well as CD4+ and CD8+ T cells’ proliferation in vitro. We proved that this immune promoting activity is activated through TLR4 and its downstream MAPK and NF–κB signaling pathways. Further in vivo (mouse model) investigation showed that LMWF has a strong immunological boosting effect, such as facilitating the proliferation of immune cells and increasing the index of immune organs. These findings suggest that LMWF has a positive immunomodulatory effect and is a promising candidate to supplement cancer immunotherapy.     

四川小麦品种高、低分子量麦谷蛋白基因和1B/1R易位的分子标记鉴定

为给四川小麦品质育种提供参考信息,利用7个HMW-GS、17个LMW-GS和1个1B/1R易位的特异分子标记,对105份2000年后育成的四川小麦品种进行上述基因检测。结果表明:(1)针对HMWGS,在Glu-A1位点,含Ax2*的品种有2份,频率为1.9%;在Glu-B1位点,含Bx7、Bx20、Bx17、By8和By9的品种分别有73、26、4、45和30份,频率分别为69.5%、24.8%、3.8%、42.9%和28.6%,未检测到含Bx7OE的品种;在Glu-D1位点,含Dx5的品种有65份,频率为61.9%。(2)针对LMW-GS,在Glu-A3位点,含Glu-A3a、Glu-A3b、Glu-A3c、Glu-A3d和Glu-A3f的品种分别有2、2、63、29和9份,频率分别为1.9%、1.9%、60.0%、27.6%和8.6%,未检测到含Glu-A3e和Glu-A3g的品种;在Glu-B3位点,含Glu-B3b、Glu-B3d、Glu-B3f、GluB3g和Glu-B3i的品种分别有18、10、1、75和1份,频率分别为17.1%、9.5%、1.0%、71.4%和1.0%,未检测到含Glu-B3a、Glu-B3c、Glu-B3e和Glu-B3h的品种。(3)含1B/1R易位的品种有36份,频率为34.3%。(4)组合6种和5种以上优质基因的品种分别有2份(频率为3.8%)和15份(频率为14.3%)。可利用这些品种作为亲本,在四川小麦品质育种中逐步导入优质基因Ax2*、Bx7、By8、Dx5、Glu-A3d、Glu-B3d、Glu-A3b和Glu-B3b,并淘汰1B/1R易位,优化四川小麦面筋优质基因组成。     

低分子量有机酸对大豆根系形态和磷素吸收积累的影响

采用砂培试验研究了几种低分子量有机酸(柠檬酸、草酸、苹果酸和三种酸的混合)对根系形态和磷素吸收积累的影响.结果表明:不同有机酸处理均显著降低了大豆根系生物量和根冠比,同时使根长、根表面积和根体积均显著降低,而且随着有机酸浓度的增加抑制作用加强,几种有机酸混合后,抑制作用也相对增强,表明不同有机酸处理均抑制了大豆根系的生长,同时使大豆根系的竞争能力降低.几种有机酸处理均降低了大豆对磷素的吸收积累,从而降低了大豆对磷素的吸收效率,但磷利用效率增加.     

The Effect of Molecular Weight on the Antimicrobial Activity of Chitosan from Loligo opalescens for Food Packaging Applications

The growing requirement for sustainable processes has boosted the development of biodegradable plastic-based materials incorporating bioactive compounds obtained from waste, adding value to these products. Chitosan (Ch) is a biopolymer that can be obtained by deacetylation of chitin (found abundantly in waste from the fishery industry) and has valuable properties such as biocompatibility, biodegradability, antimicrobial activity, and easy film-forming ability. This study aimed to produce and characterize poly(lactic acid) (PLA) surfaces coated with β-chitosan and β-chitooligosaccharides from a Loligo opalescens pen with different molecular weights for application in the food industry. The PLA films with native and depolymerized Ch were functionalized through plasma oxygen treatment followed by dip-coating, and their physicochemical properties were assessed by Fourier-transform infrared spectroscopy, X-ray diffraction, water contact angle, and scanning electron microscopy. Their antimicrobial properties were assessed against Escherichia coli and Pseudomonas putida, where Ch-based surfaces reduced the number of biofilm viable, viable but nonculturable, and culturable cells by up to 73%, 74%, and 87%, respectively, compared to PLA. Biofilm growth inhibition was confirmed by confocal laser scanning microscopy. Results suggest that Ch films of higher molecular weight had higher antibiofilm activity under the food storage conditions mimicked in this work, contributing simultaneously to the reuse of marine waste.     

The Effect of Substituent,Degree of Acetylation and Positioning of the Cationic Charge on the Antibacterial Activity of Quaternary Chitosan Derivatives

A series of water-soluble cationic chitosan derivatives were prepared by chemoselective functionalization at the amino group of five different parent chitosans having varying degrees of acetylation and molecular weight. The quaternary moieties were introduced at different alkyl spacer lengths from the polymer backbone (C-0, C-2 and C-6) with the aid of 3,6-di-O-tert-butyldimethylsilyl protection of the chitosan backbone, thus allowing full (100%) substitution of the free amino groups. All of the derivatives were characterized using ¹H-NMR, ¹H-¹H COSY and FT-IR spectroscopy, while molecular weight was determined by GPC. Antibacterial activity was investigated against Gram positive S. aureus and Gram negative E. coli. The relationship between structure and activity/toxicity was defined, considering the effect of the cationic group’s structure and its distance from the polymer backbone, as well as the degree of acetylation within a molecular weight range of 7–23 kDa for the final compounds. The N,N,N-trimethyl chitosan with 100% quaternization showed the highest antibacterial activity with moderate cytotoxicity, while increasing the spacer length reduced the activity. Trimethylammoniumyl quaternary ammonium moieties contributed more to activity than 1-pyridiniumyl moieties. In general, no trend in the antibacterial activity of the compounds with increasing molecular weight or degree of acetylation up to 34% was observed.     

Impact of Degree of Ionization and PEGylation on the Stability of Nanoparticles of Chitosan Derivatives at Physiological Conditions

Nowadays, the therapeutic efficiency of small interfering RNAs (siRNA) is still limited by the efficiency of gene therapy vectors capable of carrying them inside the target cells. In this study, siRNA nanocarriers based on low molecular weight chitosan grafted with increasing proportions (5 to 55%) of diisopropylethylamine (DIPEA) groups were developed, which allowed precise control of the degree of ionization of the polycations at pH 7.4. This approach made obtaining siRNA nanocarriers with small sizes (100–200 nm), positive surface charge and enhanced colloidal stability (up to 24 h) at physiological conditions of pH (7.4) and ionic strength (150 mmol L⁻¹) possible. Moreover, the PEGylation improved the stability of the nanoparticles, which maintained their colloidal stability and nanometric sizes even in an albumin-containing medium. The chitosan-derivatives displayed non-cytotoxic effects in both fibroblasts (NIH/3T3) and macrophages (RAW 264.7) at high N/P ratios and polymer concentrations (up to 0.5 g L⁻¹). Confocal microscopy showed a successful uptake of nanocarriers by RAW 264.7 macrophages and a promising ability to silence green fluorescent protein (GFP) in HeLa cells. These results were confirmed by a high level of tumor necrosis factor-α (TNFα) knockdown (higher than 60%) in LPS-stimulated macrophages treated with the siRNA-loaded nanoparticles even in the FBS-containing medium, findings that reveal a good correlation between the degree of ionization of the polycations and the physicochemical properties of nanocarriers. Overall, this study provides an approach to enhance siRNA condensation by chitosan-based carriers and highlights the potential of these nanocarriers for in vivo studies.     

Influences of Molecular Weights on Physicochemical and Biological Properties of Collagen-Alginate Scaffolds

For tissue engineering applications, biodegradable scaffolds containing high molecular weights (MW) of collagen and sodium alginate have been developed and characterized. However, the properties of low MW collagen-based scaffolds have not been studied in previous research. This work examined the distinctive properties of low MW collagen-based scaffolds with alginate unmodified and modified by subcritical water. Besides, we developed a facile method to cross-link water-soluble scaffolds using glutaraldehyde in an aqueous ethanol solution. The prepared cross-linked scaffolds showed good structural properties with high porosity (~93%) and high cross-linking degree (50–60%). Compared with collagen (6000 Da)-based scaffolds, collagen (25,000 Da)-based scaffolds exhibited higher stability against collagenase degradation and lower weight loss in phosphate buffer pH 7.4. Collagen (25,000 Da)-based scaffolds with modified alginate tended to improve antioxidant capacity compared with scaffolds containing unmodified alginate. Interestingly, in vitro coagulant activity assay demonstrated that collagen (25,000 Da)-based scaffolds with modified alginate (C25-A63 and C25-A21) significantly reduced the clotting time of human plasma compared with scaffolds consisting of unmodified alginate. Although some further investigations need to be done, collagen (25,000 Da)-based scaffolds with modified alginate should be considered as a potential candidate for tissue engineering applications.     

夏玉米果穗不同部位小穗轴维管束显微结构特点及其对子粒发育的影响

采用大田试验,设置不同种植密度,选用不同类型玉米品种,研究果穗小穗轴维管束的解剖结构变化及其与不同部位子粒干重的关系。结果表明,正常情况下,小穗轴维管束的韧皮部发达,且其"喇叭"结构十分有利于子粒灌浆,败育子粒的小穗轴维管束则发育不良;相同粒位,ZD958的小穗轴维管束面积显著大于ND08的小穗轴维管束面积;两个品种的小穗轴维管束面积均随密度增加而降低;小穗轴维管束的面积受密度影响较大,但受基因(品种)影响更大。耐密性品种在较高密度下小穗轴维管束的结构仍然正常,其面积虽然也减少但不足以成为灌浆障碍,这也是其获得高产的原因之一。因此,在品种选育上,应优选小穗轴维管束面积较大的材料。     

Influence of the cultivar,environment and management on the grain yield and bread-making quality in winter wheat

The genotype, environment and their interaction play an important role in the grain yielding and grain quality attributes. The main aim of this study was to determine the contributions of the genotype, environment and their interaction to the variation in bread-making traits. The data that were used for the analyses performed in this study were obtained from 3 locations in Poland from post-registration multi-environment trials with winter wheat in 2009 and 2010. The experimental factors were the cultivar (7 cultivars) and the crop management level (low input and high input). In the multi-environment trials, 17 traits were investigated that characterize grain, flour and dough quality. Most of the traits were affected much more strongly by environmental factors (i.e., year and location) than by genotype. The variance components revealed an especially strong effect of the year on the baking score, loaf volume and water absorption, as well a strong effect of the location on dough development and protein content. The obtained results demonstrate that the grain quality as measured by the parameters based on the protein content and quality may be substantially improved by crop management practices, especially by N fertilization level.     

Differential mixing action effects on functional properties and polymeric protein size distribution of wheat dough

A micro Z-arm mixer and a 2g-Mixograph were used to compare the effect of pin and Z-arm-type mixing actions on mixing properties of wheat flour dough. Although the two mixing curves obtained with pin- and Z-arm-type mixing action showed a very similar mixing trace, no significant correlation was found between the two mixers other than the number of revolutions required for optimal dough consistency (peak resistance). Mixing requirement was described by a rate-independent parameter, the number of revolutions to peak dough development and was found to be greater in a Z-arm mixer than in a pin mixer. Mixing requirement showed significant correlation with stability, which is therefore a dough strength parameter. The change in the polymeric structure of gluten proteins of dough as indicated by %UPP (unextractable polymeric protein percentage) was monitored and showed a smaller decrease with Z-arm mixing than with pin mixing. Therefore, pin-mixing action is more energetic than Z-arm mixing. At peak resistance, Z-arm mixing gives a larger quantity of polymeric protein content in the dough relative to pin mixing. The degree of dough development at maximum resistance in the different mixers was shown to be different. A new parameter, delta-_UPPMZ${\mathrm{UPP}}_{\mathrm{MZ}}$ (the difference between %UPP of dough obtained with pin vs Z-arm mixing actions) was identified and proposed to have some relationship to the stability of the polymeric proteins in the dough.