S-Trityl-L-Cysteine诱导HL-60细胞有丝分裂阻滞和凋亡

目的研究S-三苯甲基-L-半胱氨酸(S-Trityl-L-Cysteine,STLC)对急性白血病HL-60细胞有丝分裂阻滞和凋亡的影响,初步探讨药物作用下HL-60细胞有丝分裂阻滞和凋亡间的因果关系。方法将HL-60细胞分成不加药对照组和不同剂量(1、2.5、5、10、50、100μmol/L)STLC加药组,药物作用一定时间后,台盼蓝染色观察HL-60细胞活性变化,MTT法检测其对HL-60细胞的抑制效应,免疫荧光染色观察细胞及其核的特征,流式细胞术分析细胞周期和亚二倍体峰的变化,Annexin-v/PI双染检测药物处理前后正常骨髓细胞凋亡比率。结果MTT和台盼蓝染色实验显示STLC抑制HL-60细胞生长并致其死亡;免疫荧光染色见核破裂及凋亡小体和细胞体积增大等典型有丝分裂灾变细胞凋亡现象;细胞周期和凋亡分析表明STLC致HL-60细胞凋亡比率与药物浓度和作用时间呈正相关,致G2/M期阻滞比率24h和48h随药物浓度增加而升高,而72h无明显变化,进一步研究发现STLC处理早期即可致G2/M期有丝分裂阻滞和凋亡的同时发生,撤除药物作用后有丝分裂阻滞呈可逆性恢复,STLC作用下正常骨髓细胞凋亡比率无明显变化。结论STLC诱导HL-60细胞阻滞在G2/M期并致其凋亡,显示较强的抗有丝分裂和抗肿瘤效果,药物处理早期有丝分裂阻滞和凋亡同时发生提示尚有该药物作用新机制的存在。

Effects of DHA-enriched hen egg yolk and L-cysteine supplementation on quality of cryopreserved boar semen

The objective of the present study was to determine the effects of docosahexaenoic acid （DHA）-enriched hen egg yolks and L-cysteine supplementation on the qualities of the cryopreserved boar semen. A total of 15 ejaculates from 5 Pietrain boars were divided into 4 groups according to the compositions of the freezing extenders used, that is, normal hen egg yolk （group Ⅰ）, DHA-enriched hen egg yolk （group Ⅱ）, normal hen egg yolk with 5 mmol L^-1 of cysteine supplementation （group Ⅲ） and DHA-enriched hen egg yolk with 5 mmol L1 of cysteine supplementation （group Ⅳ）. The semen was cryopreserved using controlled rate freezer and was thawed at 50℃ for 12 s. Progressive motility, sperm viability, acrosome integrity and functional integrity of sperm plasma membrane of the post-thawed semen were evaluated. The supplementation of L-cysteine in the freezing extender alone （group Ⅲ） improved progressive motility （P 〈 0.05）, and the supplementation of L-cysteine in combination with DHA-enriched hen egg yolk （group Ⅳ） improved both progressive motility （P 〈 0.05） and acrosome integrity （P 〈 0.01）. The use of DHA-enriched hen egg yolk alone （group Ⅱ） did not enhance any of the post-thawed semen qualities （P 〉 0.05）. In conclusion, the supplementation of antioxidant L-cysteine alone or in combination with DHA-enriched hen egg yolk significantly improved the post-thawed semen qualities, especially progressive motility and acrosome integrity.

Supplemental effect of varying L-cysteine concentrations on the quality of cryopreserved boar semen

Cryopreservation is associated with the production of reactive oxygen species, which leads to lipid peroxidation of the sperm membrane and consequently a reduction in sperm motility and decreased fertility potential. The aim of this study was to determine the optimal concentration of L-cysteine needed for cryopreservation of boar semen. Twelve boars provided semen of proven motility and morphology for this study. The semen was divided into four portions in which the lactose-egg yolk （LEY） extender used to resuspend the centrifuged sperm pellet was supplemented with various concentrations of L-cysteine to reach 0 mmol L^-1 （group Ⅰ, control）, 5 mmol L^-1 （group Ⅱ）, 10 mmol L^-1 （group Ⅲ） and 15 mmol L^-1 （group Ⅳ）. Semen suspensions were loaded in straws （0.5 mL） and placed in a controlled-rate freezer. After cryopreservation, frozen semen samples were thawed and investigated for progressive motility, viability using SYBR-14/EthD-1 staining and acrosome integrity using FITC-PNA/EthD-1 staining. There was a significantly higher （P 〈 0.01） percentage of progressive motility, viability and acrosomal integrity in two L-cysteine-supplemented groups （group Ⅱ and group Ⅲ） compared with the control. There was a biphasic effect of L-cysteine, with the highest percentage of progressive motility, viability and acrosomal integrity in group Ⅲ. In conclusion, 5 or 10 mmol L^-1 was the optimum concentration of L-cysteine to be added to the LEY extender for improving the quality of frozen-thawed boar semen.

A potent chemotherapeutic strategy in prostate cancer： S-（methoxytrityl）-L-cysteine, a novel Eg5 inhibitor

Docetaxel-based combination chemotherapy remains the predominant treatment for castration-resistant prostate cancer. However, taxane-related drug resistance and neurotoxicity have prompted us to develop substitute treatment strategies. Eg5 （kinesin spindle protein）, which is crucial for bipolar spindle formation and duplicated chromosome separation during the early phase of mitosis, has emerged as an attractive target for cancer chemotherapy. The aim of this study was to investigate the anticancer efficacy of $-（methoxytrityl）-L-cysteine （S（MeO）TLC）, a novel Eg5 inhibitor in prostate cancer. Eg5 expression was examined in human prostate cancer cell lines and tissue microarrays were constructed from clinical specimens. Antiproliferative activity of S（MeO）TLC in prostate cancer cells was assessed by a cell viability assay. The anticancer effect and inhibitory mechanism of S（MeO）TLC in prostate cancer cells was further explored by Hoechst staining, flow cytometry and immunofluorescence. In addition, the antitumor effect of S（MeO）TLC on subcutaneous xenograft models was assessed. Eg5 expression was identified in PC3, DU145 and LNCaP cells. More than half of prostate cancer clinical specimens displayed Eg5 expression. S（Me0）TLC exhibited more powerful anticancer activity in prostate cancer cells compared with the other four Eg5 inhibitors tested. S（MeO）TLC induced cell death after arresting dividing cells at mitosis with distinct monopolar spindle formation. S（MeO）TLC exhibited its significant inhibitory activity （P〈0.05） on subcutaneous xenograft models also through induction of mitotic arrest. We conclude that Eg5 is a good target for prostate cancer chemotherapy, and S（MeO）TLC is a potent promising anticancer agent in prostate cancer.

Influence of L-Cysteine Concentration on Oxidation-reduction Potential and Biohydrogen Production

The effects of L-cysteine concentration on biohydrogen production by Enterobacterium Bacterium M580 were investigated in batch cultivation.The experimental results showed that L-cysteine could enhance the cell growth,hydrogen production rate and hydrogen yield when its concentration was less than 500 mg·L-1,while it had negative effects when its concentration was higher than 500 mg·L-1.The hydrogen production was the highest 1.29 mol·mol-1(H2/glucose) when 300 mg·L-1L-cysteine was added into the culture,and the yield was 9.4% higher than that in the control.The oxidation-reduction potential(ORP) ,which was influenced by L-cysteine,also affected hydrogen production.The ORP values were in the range-300 mV to-150 mV when the L-cysteine concentration was higher than 500 mg·L-1.Although the ORP in this range was favorable for hydrogen production,it was not suitable for the biomass growth.Hence,less hydrogen was produced.When the L-cysteine concentration was lower than 500 mg·L-1,the ORP was more suitable for both biomass growth and hydrogen production.In addition,at least 91%glucose was consumed when L-cysteine was added to the culture media,compared to the 97.37% consumption without L-cysteine added.

Electrochemical investigation on the film of L-cysteine self-assembled to nanoparticles on a gold electrode

The film contained L-cysteine and gold nanoparticles were provided by self-assembled monolayers (SAMs) and potentiostatic electrodeposition technology on the gold electrode. Two methods were used to study the film: In the first, cyclic voltammetry (CV) was used to inspect the functional groups of the film and the same time hydroquinone was chosen to be a probe molecule in the based solution;secondly, based on analytical technology of scanning electrochemical microscopy (SECM), the heterogeneous rate constant (keff) between solid phase (the modified electrode) and liquid phase (K3Fe(CN)6) was obtained. As a result, the better binary catalysis of hydroquinone was demonstrated and the heterogeneous rate constant (keff) is the greater at 8 h for L-cysteine self-assembled monolayers (SAMs).

L-Cysteine-assisted Synthesis of Copper Gallium Sulfide Microspheres

An effective L-cysteine-assisted synthetic route has been successfully developed to prepare copper gallium sulfide（CuGaS2） microspheres under solvothermal conditions with CuCI2.2HzO, GaC13 and L-cysteine as source materials, in which L-cysteine was used as the sulfide source and complexing molecule. The experiments revealed that the synthesized sample was of a typical CuGaS2 tetragonal structure. Moreover, the prepared CuGaS2 crystals consisting of microspheres made up of nanoflakes, and the diameter of the nanoflakes was about 20 nm. Raman spectrum of the obtained CuGaS2 exhibits a high-intensity peak of the A1 mode at 306 cm^-1. Meanwhile, a possible growth mechanism was proposed based on the investigations.

Effect of L-cysteine on bioleaching of Ni-Cu sulphide by A. manzaensis

The effect of L-cysteine in different concentrations on the bioleaching of Ni-Cu sulfide was studied with an extremely thermophilic archaea,Acidianus manzaensis. It is found that adding certain amounts of L-cysteine to the bioleaching system of Ni-Cu sulfide largely enhances the leaching rate. X-ray diffraction (XRD) patterns show the change of bioleached solid residues and the effect of L-cysteine on the surface charges of minerals. Zeta potential and IR spectra of mineral surface show that the interaction between L-cysteine and mineral leads to the formation of metal complex,which is propitious to the bioleaching of Ni-Cu sulfide by Acidianus manzaensis.

Electrocatalytic oxidation behavior of L-cysteine at Pt microparticles modified nanofibrous polyaniline film electrode

Platinum(Pt)/nanofibrous polyaniline(PANI) electrode was prepared by pulse galvanostatic method and characterized by scanning electron microscopy.The electrochemical behavior of L-cysteine at the Pt/nanofibrous PANI electrode was investigated by cyclic voltammetry.The results indicate that the pH value of the solution and the Pt loading of the electrode have great effect on the electrocatalytic property of the Pt /nanofibrous PANI electrode;the suitable Pt loading of the electrode is 600 μg/cm2 and the suitable pH value of the solution is 4.5 for investigating L-cysteine oxidation.The L-cysteine sensor based on the Pt/nanofibrous PANI electrode has a good selectivity,reproducibility and stability.The Pt/nanofibrous PANI electrode is highly sensitive to L-cysteine,and the linear calibration curve for the oxidation of L-cysteine can be observed in the range of 0.2-5.0 mmol/L.

Reparative histogenesis of skin: Reaction on the application of l-cysteine of argentum nitrate gel

The effect of L-cysteine of argentum nitrate gel on the wound process of experimental animals is investigated. The results show that the nanogel, being bacteriostatic, accelerates the course of inflammation phase resulting in fast cleansing of the wound surface and stimulation of the granulation tissue formation. The main cell elements of this tissue—fibroplasts are characterized by the state of functional excitation. The time of wound healing with the use of L-cysteine of argentum nitrate gel was reduced by three days, and the index of wound repair acceleration was about 20%.

Hepatic Protective Effects of <i>S</i>-Allyl-L-Cysteine (SAC) in Rats with Carbon Tetrachloride (CCl₄) Induced Liver Injury

S-allyl-L-cysteine (SAC) is an organosulfur compound derived from aged garlic extract (AGE). Studies have reported that AGE possesses bioprotective capacity, including antidiabetic, antimicrobial, antioxidant, and antitumor effects. The present study examined the protective effects of SAC against carbon tetrachloride (CCl4) induced hepatotoxicity in rats. Ten male Wistar rats aged 11 - 12 weeks were randomly divided into two groups (five rats/group) as control and SAC groups. All rats had ad libitum access to water, and the SAC group received water containing SAC intragastrically (200 mg/kg) once daily for five consecutive weeks. In the fifth experimental week, 50% CCl4 in olive oil (1 mL/kg) was administered intraperitoneally three times a week to induce liver injury in both groups. Rats were sacrificed at 24 hours after the last CCl4 injection, and liver tissues were excised for histopathological, immunohistochemical and antioxidant analyses. The rats in the SAC group did not show abnormal behavior, such as decreased water intake or food consumption, during the experimental period. Body weights in all groups did not change significantly over the experimental period. Histopathological analysis showed that the percentage of hepatic steatosis was lower in the SAC group at 12.75% ± 3.74% compared to 24.64% ± 5.29% in the control group (p < 0.05). The percentage of cytochrome P4502E1 (CYP2E1) distribution area in the SAC group was also lower at 19.61% ± 6.18% compared with 25.22% ± 6.21% in the control group (p < 0.05). These results suggest that SAC can alleviate CCl4-induced liver damage by decreasing hepatic steatosis and reducing CYP2E1 expression in rats.

Design and fabrication of highly hydrophilic magnetic material by anchoring L-cysteine onto chitosan for efficient enrichment of glycopeptides

Hydrophilic interaction liquid chromatography(HILIC) has been recognized as an effective strategy for glycopeptide enrichment. Hydrophilic materials pave the way to solve the limit of low enrichment capacity and poor selectivity. The present study is the first attempt to combine chitosan(CS) and L-cysteine(L-Cys) to design a novel hydrophilic material focusing on glycopeptide enrichment. CS containing a large number of hydrophilic amino and hydroxyl groups has unique chemical properties, which makes it a very attractive biomaterial for glycopeptide enrichment. The excellent hydrophilicity of zwitterionic molecule L-Cys inspires the idea of anchoring L-Cys onto CS to design a novel hydrophilic material(named as Fe_(3)O_(4)@CS@Au-L-Cys) for the capture of low abundance glycopeptides. To be specific, Au nanoparticles(Au NPs) was introduced into CS-coated Fe_(3)O_(4)via electrostatic interaction and served as bridges to anchor L-Cys onto the surface of CS through strong Au-S bond interaction. The prepared Fe_(3)O_(4)@CS@AuL-Cys exhibited strong affinity, low detection limit(0.5 fmol/μL HRP), high selectivity(HRP/BSA with a molar ratio of 1:1000) for glycopeptides. Moreover, successful application of glycopeptide enrichment in human serum and saliva by Fe_(3)O_(4)@CS@Au-L-Cys was achieved. A satisfactory data set indicates that Fe_(3)O_(4)@CS@Au-L-Cys has promising potential in the application of glycopeptide enrichment in real complex bio-samples and for related glycoproteome research.

The miR-9-5p/CXCL11 pathway is a key target of hydrogen sulfide-mediated inhibition of neuroinflammation in hypoxic ischemic brain injury

We previously showed that hydrogen sulfide(H2S)has a neuroprotective effect in the context of hypoxic ischemic brain injury in neonatal mice.However,the precise mechanism underlying the role of H2S in this situation remains unclear.In this study,we used a neonatal mouse model of hypoxic ischemic brain injury and a lipopolysaccharide-stimulated BV2 cell model and found that treatment with L-cysteine,a H2S precursor,attenuated the cerebral infarction and cerebral atrophy induced by hypoxia and ischemia and increased the expression of miR-9-5p and cystathionineβsynthase(a major H2S synthetase in the brain)in the prefrontal cortex.We also found that an miR-9-5p inhibitor blocked the expression of cystathionineβsynthase in the prefrontal cortex in mice with brain injury caused by hypoxia and ischemia.Furthermore,miR-9-5p overexpression increased cystathionine-β-synthase and H2S expression in the injured prefrontal cortex of mice with hypoxic ischemic brain injury.L-cysteine decreased the expression of CXCL11,an miR-9-5p target gene,in the prefrontal cortex of the mouse model and in lipopolysaccharide-stimulated BV-2 cells and increased the levels of proinflammatory cytokines BNIP3,FSTL1,SOCS2 and SOCS5,while treatment with an miR-9-5p inhibitor reversed these changes.These findings suggest that H2S can reduce neuroinflammation in a neonatal mouse model of hypoxic ischemic brain injury through regulating the miR-9-5p/CXCL11 axis and restoringβ-synthase expression,thereby playing a role in reducing neuroinflammation in hypoxic ischemic brain injury.

N-乙酰半胱氨酸对冻融人卵巢组织的保护作用

目的以首都医科大学附属北京妇产医院生育力保护中心现有冻存复苏方案为基础,以雌性去势裸鼠为模型,通过人冻融卵巢组织异种移植探讨抗氧化剂N-乙酰半胱氨酸(N-Acetyl-L-Cysteine,NAC)对人卵巢组织的保护作用。方法将4例患者的卵巢组织按照原有冻融方案和改良方案(加入NAC)进行冻融,所有患者取材后留取新鲜卵巢组织进行钙黄绿素AM(Calcein acetoxymethyl ester,Calcein-AM)和苏木精-伊红(hematoxylin-eosin staining,HE)染色评估卵泡活性并计数。将36只雌性去势裸鼠随机分为4组,将复苏后的卵巢组织移植于双侧裸鼠肾被膜下,按照移植卵巢组织的冻融方案分为原有冻融方案组(control group),改良方案组(NAC group),卵巢去势组(ovariectomy group)和正常对照组(normal group,不进行手术)。分别在移植第3天、第7天、第21天处死裸鼠,取血清及卵巢组织移植物。采用酶联免疫吸附试验(enzyme-linked immunosorbent assay,ELISA)法检测血清雌二醇(estradiol,E2)、卵泡刺激素(follicle stimulating hormone,FSH)和抗苗勒管激素(anti-mullerian hormone,AMH)水平,取卵巢组织移植物1片用于HE染色观察卵泡发育情况,1片用于总抗氧化能力(total antioxidant capability,TAC)的检测。结果移植后各时间点两移植组卵泡发育分级差异无统计学意义(P>0.05)。NAC组总抗氧化能力显著高于control组(P<0.05),与新鲜卵巢组织相比差异无统计学意义(P>0.05)。移植第3天control组裸鼠血清中E2水平显著高于卵巢去势组(P<0.05),余各时间点两移植组与卵巢去势组差异无统计学意义(P>0.05)。移植后第3天和第21天两移植组裸鼠血清中FSH水平低于卵巢去势组(P<0.05),与正常对照组差异无统计学意义(P>0.05)。移植后第3天control组AMH显著高于卵巢去势组(P<0.05),与其余各组差异无统计学意义(P>0.05),移植第7天两移植组AMH水平下降,显著低于正常对照组(P<0.05),移植第21天两移植组AMH水平均显著高于卵巢去势组(P<0.05),与正常对照组差异无统计学意义(P>0.05)。结论原有冻存方案及改良冻存方案均能有效恢复卵巢组织的内分泌功能。与原有冻存方案相比,NAC改良方案能够提高移植卵巢组织的抗氧化能力,并减少移植初期原始卵泡的激活,保存更多的原始卵泡数量。

L-半胱氨酸改性甲基纤维素自愈合水凝胶的制备及其性能研究

以甲基纤维素(MC)为水凝胶主体,通过Steglich酯化反应将L-半胱氨酸(Cys)接枝在MC上,从而引入巯基形成动态的二硫键,合成增强型自愈合水凝胶MC-Cys。采用傅里叶变换红外光谱仪、扫描电子显微镜、核磁共振氢谱仪、流变仪、热重分析仪等对水凝胶的结构和性能进行表征。结果表明,MC-Cys水凝胶的最大拉伸强度能达到1.251MPa,比纯MC水凝胶拉伸强度(0.626MPa)提高了1倍,动态的二硫键赋予了MC-Cys水凝胶自愈合性,在生物医学、组织工程等领域应用前景广阔。

Cloning,expression and characterization of L-cysteine desulfhydrase gene from Pseudomonas sp.TS1138

L-cysteine desulfhydrase(CD)plays an impor-tant role in L-cysteine decomposition.To identify the CD gene in Pseudomonas sp.TS1138 and investigate its effect on the L-cysteine biosynthetic pathway,the CD gene was cloned from Pseudomonas sp.TS1138 by polymerase chain reaction(PCR)method.The nucleotide sequence of CD gene was determined to be 1,215 bp,and its homology with other sequences encoding CD was analyzed.Then the CD gene was subcloned into pET-21a(+)vector and expressed in Escherichia coli(E.coli)by isopropyl-β-D-thiogalacto-pyranoside(IPTG)inducement.The recombinant CD was purified by Ni-NTA His-Bind resin,and its activity was identified by the CD activity staining.The enzymatic proper-ties of the recombinant CD were characterized and its critical role involved in the L-cysteine biosynthetic pathway was also discussed.

L-半胱氨酸对绵羊卵巢颗粒细胞增殖、凋亡和类固醇激素分泌的影响

旨在探讨L-半胱氨酸(L-Cys)对体外培养绵羊卵巢颗粒细胞(GCs)增殖、凋亡和类固醇分泌的影响。本研究采集1~1.5岁龄体重相近饲养条件相同的30只健康性成熟小尾寒羊母羊新鲜卵巢,从优势卵泡(2~8 mm)中收集GCs,随机分为5组,每组6个重复,各组添加L-Cys浓度分别为0、100、300、500和700μmol·L^(-1),培养48 h后用CCK-8试剂盒进行细胞增殖活力测定,Annexin V-FITC/PI流式细胞仪检测GCs的凋亡情况,采用ELISA检测GCs培养液上清中孕酮和雌二醇的分泌水平并采用实时荧光定量PCR和Western blot分析L-Cys对绵羊颗粒细胞增殖相关基因(PCNA、CCND2、CCNB 1)、凋亡相关基因(BAX、Caspase-3、Bcl-2)和类固醇分泌相关基因的(STAR、3β-HSD、CYP 11A1、CYP 19A1)mRNA和蛋白表达的影响。结果显示,100、300和500μmol·L^(-1)组的L-Cys均可显著促进绵羊GCs的增殖活力(P<0.05),并显著抑制其凋亡率(P<0.05)。添加300μmol·L^(-1)的L-Cys显著抑制了孕酮(P 4,P<0.05)的分泌。进一步研究发现,300μmol·L^(-1)和500μmol·L^(-1)组的L-Cys可以上调增殖相关基因(PCNA、CCND2、CCNB 1)mRNA表达水平,其中300μmol·L^(-1)组的增殖蛋白(PCNA、CCND2、CCNB1)表达量显著上升(P<0.05);100μmol·L^(-1)和300μmol·L^(-1)组显著下调凋亡相关基因(BAX、Caspase-3)mRNA(P<0.05)及其蛋白表达水平(P<0.05)。添加300μmol·L^(-1)L-Cys显著降低了类固醇相关基因(STAR、3β-HSD)mRNA及蛋白表达水平(P<0.05),添加100μmol·L^(-1)和300μmol·L^(-1)L-Cys显著升高了类固醇相关基因(CYP 11A1、CYP 19A1)mRNA(P<0.05)及其蛋白表达水平(P<0.05)。综上,L-Cys通过上调基因PCNA、CCNB1、CCND2、Bcl-2 mRNA及其蛋白表达、下调基因BAX、Caspase-3 mRNA及其蛋白表达,促进绵羊GCs增殖,抑制其凋亡;L-Cys通过下调基因STAR、3β-HSD mRNA及其蛋白表达以及上调基因CYP 11A1 mRNA及其蛋白表达抑制P 4的分泌。

大蒜辣素在大鼠体内转化产物S-烯丙基巯基-L-半胱氨酸的鉴别

目的鉴别大鼠给药后大蒜辣素体内转化产物S-烯丙基巯基-L-半胱氨酸,探讨血浆和皮肤组织中S-烯丙基巯基-L-半胱氨酸的变化情况。方法取SD大鼠,雌雄各半,体重(200±20)g,随机分为8组,分别为空白组及给药后不同时间组,每组每个时间点采用6只大鼠,涂抹大蒜软膏于大鼠背部,分别于0、5、10、15、20、25、30、60 min依次取血液和皮肤组织,UPLC-MS/MS鉴定血液和皮肤组织中大蒜辣素的转化产物S-烯丙基巯基-L-半胱氨酸及变化情况。结果大蒜辣素与半胱氨酸反应产生S-烯丙基巯基-L-半胱氨酸,30 min即可反应90%以上。血浆中转化产物S-烯丙基巯基-L-半胱氨酸在4 h内稳定。UPLC-MS/MS鉴定并确定了皮肤组织和血浆样品大蒜辣素与内源性半胱氨酸的反应产物S-烯丙基巯基-L-半胱氨酸,给予大蒜软膏30 min内血浆和皮肤中S-烯丙基巯基-L-半胱氨酸的浓度逐步增大,60 min时含量降低。结论大蒜辣素可与血浆和组织中的内源性半胱氨酸快速反应,本研究将为大蒜辣素的后续研究提供重要依据。

L-半胱氨酸处理铜基吸液芯亲水工艺与机理研究

目的研究L-半胱氨酸浸渍处理工艺对铜基表面亲水性能的影响,并采用获得的最优工艺处理吸液芯来实现表面改性,提高吸液芯毛细能力,从而优化均热板的传热效率。方法设置温度、时间、浓度进行三因素五水平正交实验;利用接触角测量仪测定测试样品与水之间的接触角;使用相同时间内水在吸液芯层垂直爬升高度来表征毛细攀升能力;用扫描电子显微镜(SEM)观察处理前后吸液芯微观形貌,用能谱仪(EDS)研究吸液芯处理前后表面元素变化情况,用X射线光电子能谱(XPS)研究处理前后吸液芯表面元素价态变化,用测温平台测量处理前后吸液芯制成的均热板热阻。结果正交实验反映了浓度、时间、温度对处理后的铜板与水的接触角影响力,浓度最高,温度最低;L-半胱氨酸处理后的吸液芯毛细能力提高了约40%;吸液芯处理前后的微观形貌发生显著变化;XPS显示S峰结合能向低结合能方向发生偏移,部分铜由1价转化成2价;处理后的试样在相同功率条件下,与处理前相比,在传热效率方面表现出显著的温差优势,其极限传热功率提升约200 W。结论L-半胱氨酸浸渍处理铜基能明显提高铜表面亲水性,使用最佳工艺能够提高均热板吸液芯的毛细能力,从而提高均热板的传热性能。

L-Cysteine inhibits root elongation through auxin/PLETHORA and SCR/SHR pathway in Arabidopsis thaliana

L-Cysteine plays a prominent role in sulfur metabo- lism of plants. However, its role in root development is largely unknown. Here, we report that L-cysteine reduces primary root growth in a dosage-dependent manner. Elevating cellular L-cysteine level by exposing Arabidopsis thaliana seedlings to high L-cysteine, buthionine sulphoximine, or O-acetylserine leads to altered auxin maximum in root tips, the expression of quiescent center cell marker as well as the decrease of the auxin carriers PIN1, PIN2, PIN3, and PIN7 of primary roots. We also show that high L-cysteine significantly reduces the protein level of two sets of stem cell specific transcription factors PLETHORA1/2 and SCR/SHR. However, L-cysteine does not downregulate the transcript level of PiNs, PLTs, or SCR/SHR, suggesting that an uncharacterized post-transcriptional mechanism may regulate the accumulation of PIN, PLT, and SCR/SHR proteins and auxin transport in the root tips. These results suggest that endogenous L-cysteine level acts to maintain root stem cell niche by regulating basal- and auxin-induced expression of PLT1/2 and 5CR/SHR. L-Cysteine may serve as a link between sulfate assimilation and auxin in regulating root growth.