• 【用可生物降解的聚-L-丙交酯支架进行动脉吻合支架:1和6周后的初步研究。】 复制标题 收藏 收藏
    DOI:10.1583/05-1726MR.1 复制DOI
    作者列表:Bünger CM,Grabow N,Sternberg K,Ketner L,Kröger C,Lorenzen B,Hauenstein K,Schmitz KP,Kreutzer HJ,Lootz D,Ince H,Nienaber CA,Klar E,Schareck W
    BACKGROUND & AIMS: PURPOSE:To assess the technical feasibility, thrombogenicity, and biocompatibility of a new biodegradable poly-L-lactic acid (PLLA) anastomotic stent. METHODS:A polytetrafluoroethylene bifurcated graft was implanted in 17 pigs through a midline abdominal incision. After transverse graft incision, 17 316L stainless steel stents and 17 PLLA stents were randomly implanted at both iliac anastomotic sites and deployed with a 6-mm balloon under direct vision without angiography. Intended follow-up was 1 week in 6 pigs receiving oral acetylsalicylic acid (ASA) and in 7 pigs receiving ASA/clopidogrel; 4 pigs receiving ASA/clopidogrel were followed for 6 weeks. At the end of the study, the segments containing the stents were surgically explanted and processed for histology to measure the mean luminal diameter, intimal thickness, and the vascular injury and inflammation scores. RESULTS:Initial technical success of stent placement was achieved in all animals without rupture of the suture. Two pigs died (unrelated to the stent) at 3 days after operation (1 in groups A and B). At 1 week, all PLLA stents showed thrombotic occlusion with the use of ASA alone. In contrast, all PLLA stents remained patent with concurrent administration of ASA/clopidogrel. All metal stents were patent regardless of the antiplatelet regimen. The mean luminal diameter of patent PLLA stents (4.13+/-0.17 mm) was comparable to metal stents (4.27+/-0.35 mm, p=0.78) at 1 week, but significantly diminished at 6 weeks (3.21+/-0.44 versus 4.19+/-0.18 mm, p=0.005). Histological analysis showed no signs of excessive recoil. PLLA stents induced a higher inflammation score (1.79+/-0.56) and more intimal hyperplasia (0.34+/-0.11 mm) compared to metal stents [1.27+/-0.44 mm (p<0.001) and 0.18+/-0.04 mm (p=0.006), respectively] at 6 weeks. Vascular injury was comparable between PLLA and metal stents. CONCLUSION:Biodegradable PLLA stents showed higher thrombogenicity and reduced patency compared to metal stents during early follow-up. Although ASA and clopidogrel prevented thrombotic occlusion, the increased inflammatory response and neointima formation remain major concerns of PLLA stents. A solution to this problem might be the incorporation of anti-inflammatory drugs into the PLLA stent.
    背景与目标: 目的:评估新型可生物降解的聚-L-乳酸(PLLA)吻合支架的技术可行性,血栓形成性和生物相容性。
    方法:通过腹部中线切口将聚四氟乙烯分叉移植物植入17头猪。横向移植后,将17个316L不锈钢支架和17个PLLA支架随机植入两个both吻合部位,并在不进行血管造影的情况下在直视下用6毫米球囊展开。预期的随访结果是:6头接受口服乙酰水杨酸(ASA)的猪和7头接受ASA /氯吡格雷的猪。对4只接受ASA /氯吡格雷的猪进行了6周的随访。在研究结束时,将包含支架的节段进行外科手术切除并进行组织学处理,以测量平均腔直径,内膜厚度以及血管损伤和炎症评分。
    结果:在所有动物中均未发生缝线破裂的情况下,支架植入取得了初步的技术成功。手术后3天有2头猪死亡(与支架无关)(A和B组为1只)。在第1周,仅使用ASA时,所有PLLA支架均显示血栓闭塞。相反,所有PLLA支架在同时使用ASA /氯吡格雷的情况下仍保持专利。无论抗血小板方案如何,所有金属支架均已获得专利。专利PLLA支架的平均腔直径(4.13 /-0.17 mm)在1周时可与金属支架(4.27 /-0.35 mm,p = 0.78)相媲美,但在6周时显着减小(3.21 // 0.44对4.19 /-) 0.18毫米,p = 0.005)。组织学分析显示没有过度后坐的迹象。与金属支架[1.27 /-0.44 mm(p <0.001)和0.18 /-0.04 mm(p = 0.006)相比,PLLA支架引起更高的炎症评分(1.79 /-0.56)和更多的内膜增生(0.34 /-0.11 mm)。分别]在6周。 PLLA和金属支架之间的血管损伤相当。
    结论:在早期随访中,与金属支架相比,可生物降解的PLLA支架显示出更高的血栓形成性和通畅性降低。尽管ASA和氯吡格雷预防了血栓闭塞,但炎症反应和新内膜形成的增加仍然是PLLA支架的主要关注点。解决该问题的方法可能是将抗炎药掺入PLLA支架中。
  • 【马铃薯(Solanum tuberosum L.)对部分根区干燥的生理响应:ABA信号传递,叶片气体交换和水分利用效率。】 复制标题 收藏 收藏
    DOI:10.1093/jxb/erl131 复制DOI
    作者列表:Liu F,Shahnazari A,Andersen MN,Jacobsen SE,Jensen CR
    BACKGROUND & AIMS: :The physiological responses of potato (Solanum tuberosum L. cv. Folva) to partial root-zone drying (PRD) were investigated in potted plants in a greenhouse (GH) and in plants grown in the field under an automatic rain-out-shelter. In the GH, irrigation was applied daily to the whole root system (FI), or to one-half of the root system while the other half was dried, for 9 d. In the field, the plants were drip irrigated either to the whole root system near field capacity (FI) or using 70% water of FI to one side of the roots, and shifted to the other side every 5-10 d (PRD). PRD plants had a similar midday leaf water potential to that of FI, whereas in the GH their root water potential (Psi(r)) was significantly lowered after 5 d. Stomatal conductance (g(s)) was more sensitive to PRD than photosynthesis (A) particularly in the field, leading to greater intrinsic water use efficiency (WUE) (i.e. A/g(s)) in PRD than in FI plants on several days. In PRD, the xylem sap abscisic acid concentration ([ABA](xylem)) increased exponentially with decreasing Psi(r); and the relative [ABA](xylem) (PRD/FI) increased exponentially as the fraction of transpirable soil water (FTSW) in the drying side decreased. In the field, the leaf area index was slightly less in PRD than in FI treatment, while tuber biomass was similar for the two treatments. Compared with FI, PRD treatment saved 30% water and increased crop water use efficiency (WUE) by 59%. Restrictions on leaf area expansion and g(s) by PRD-induced ABA signals might have contributed to reduced water use and increased WUE.
    背景与目标: :在温室(GH)的盆栽植物和自动防雨棚田间种植的植物中,研究了马铃薯(Solanum tuberosum L. cv。Folva)对部分根区干燥(PRD)的生理响应。在GH中,每天对整个根系(FI)或一半的根系进行灌溉,而另一半干燥9 d。在田间,将植物滴灌至接近田间持水量(FI)的整个根系,或使用70%的FI水将其滴到根的一侧,然后每5-10 d(PRD)移至另一侧。珠三角植物的中午叶片水势与FI相似,而在GH中,其根系水势(Psi(r))在5天后显着降低。尤其是在田间,气孔电导(g(s))比光合作用(A)对PRD更敏感,因此在几个地方,PRD中的固有水分利用效率(WUE)(即A / g(s))比FI植物更大。天。在珠三角地区,木质部汁液中脱落酸的浓度([ABA](木质部))随着Psi(r)的降低呈指数增长。相对[ABA](木质部)(PRD / FI)随干旱侧可蒸发土壤水(FTSW)比例的减少呈指数增长。在田间,珠三角的叶面积指数略低于FI处理,而两种处理的块茎生物量相似。与FI相比,PRD处理节省了30%的水,并使作物水分利用效率(WUE)提高了59%。 PRD诱导的ABA信号对叶面积扩大和g(s)的限制可能有助于减少用水量和增加WUE。
  • 【吡虫啉和碳硫丹在芒果中的持久性行为(Mangifera indica L.)。】 复制标题 收藏 收藏
    DOI:10.1007/s00128-012-0902-6 复制DOI
    作者列表:Bhattacherjee AK
    BACKGROUND & AIMS: :Imidacloprid was sprayed on mango cv. Dashehari at 0.3 mL L(-1) of water during pre-bloom stage with 6-8 cm panicle size (first week of March) to control hopper and carbosulfan was sprayed at 2.0 mL L(-1) of water in the trees of mango hybrid (H-1000) during fruit development stage (first week of May) to control leaf webber. Residues of both the insecticides were analysed in peel, pulp and fruit at different stages of fruit development and maturity. The initial residues of imidacloprid, after 30 days of spraying, were 1.21, 0.56 and 1.77 mg kg(-1) in peel, pulp and whole fruit, respectively. The residues persisted in peel for 60 days and in pulp for 50 days and dissipated with a half-life of 38 days. Mature Dashehari fruits at harvest (after 85 days of spraying) were free from imidacloprid residues. Carbosulfan in mango peel dissipated from 5.30 mg kg(-1) (after 1 h of spraying) to 0.05 mg kg(-1) at the time of harvest (after 45 days of spraying). Carbosulfan residue in pulp was very low (0.08 mg kg(-1)) after 1 h of spraying, which increased gradually to 0.90 mg kg(-1) after 10 days and finally came down to 0.04 mg kg(-1) after 26 days of spraying. The insecticide residue was not detected in the pulp at the time of harvest. The residues persisted in pulp for 26 days and in peel for 45 days and degraded with a half-life of 7 days. The dissipation of both imidacloprid and carbosulfan followed first order rate kinetics in whole fruit (peel + pulp). Therefore, the safe pre-harvest intervals were suggested to be 55 days for imidacloprid and 46 days for carbosulfan before consumption of mango fruits after spraying of these insecticides.
    背景与目标: :吡虫啉喷在芒果简历上。在花前期,以6-8厘米穗大小(3月的第一周)控制漏斗,以0.3 mL L(-1)水的Dashehari喷洒在树木的树上,以2.0 mL L(-1)的水喷洒芒果杂种(H-1000)在果实发育阶段(5月的第一周)以控制叶片韦伯。在水果发育和成熟的不同阶段,对果皮,果肉和水果中两种杀虫剂的残留进行了分析。喷洒30天后,吡虫啉的初始残留分别为果皮,果肉和整个水果中的1.21、0.56和1.77 mg kg(-1)。残留物在果皮中持续60天,在果肉中持续50天,并以38天的半衰期消散。收获时(喷洒85天后)成熟的Dashehari果实不含吡虫啉残留。芒果皮中的硫丹从收获时(喷雾45天后)从5.30 mg kg(-1)(喷雾1 h后)消散至0.05 mg kg(-1)。喷洒1 h后纸浆中的硫丹残留量非常低(0.08 mg kg(-1)),经过10天后逐渐增加至0.90 mg kg(-1),最后在26天后降至0.04 mg kg(-1)喷涂天数。收获时在果肉中未检测到杀虫剂残留。残留物在果肉中持续26天,在果皮中持续45天,并以7天的半衰期降解。吡虫啉和硫丹的消散都遵循整个水果(果皮果皮)中的一级速率动力学。因此,建议在喷洒这些杀虫剂后食用芒果果实之前,吡虫啉的安全收获前间隔为55天,碳硫丹为46天。
  • 【抑制钠依赖性L-亮氨酸在大鼠脑突触小体中的摄取。】 复制标题 收藏 收藏
    DOI:10.1016/0006-2952(90)90213-5 复制DOI
    作者列表:Tan CH,Ng FH
    BACKGROUND & AIMS: :Synaptosomes isolated from adult rat cerebral cortices were used for studying the uptake of L-leucine by the Na(+)-dependent route. Three non-metabolizable amino acid analogues, which had been used previously to discriminate the Na(+)-dependent A-type uptake system of animal cells, were employed in this study. It was found that Na(+)-dependent uptake of leucine was insensitive to inhibition by 2-aminoisobutyric acid (AIB) and N-methylaminoisobutyric acid (MeAIB) whereas N-methylalanine (NMA) was markedly inhibitory. Inhibition by NMA was stereospecific--only the L-isomer had a pronounced effect. Na(+)-dependent uptake of leucine as well as its inhibition by L-NMA were rather insensitive to changes in pH from 6 to 9. Kinetic analysis of inhibition by L-NMA of Na(+)-dependent uptake revealed a non-competitive type of inhibition with a Ki value of approximately 0.5 mM.
    背景与目标: :从成年大鼠大脑皮层分离的突触体用于研究Na()依赖途径对L-亮氨酸的摄取。在这项研究中使用了三种不可代谢的氨基酸类似物,这些氨基酸类似物先前已用于区分动物细胞的Na(-)依赖性A型摄取系统。发现亮氨酸的Na()依赖性摄取对2-氨基异丁酸(AIB)和N-甲基氨基异丁酸(MeAIB)的抑制不敏感,而N-甲基丙氨酸(NMA)具有明显的抑制作用。 NMA的抑制作用是立体特异性的-只有L-异构体具有明显的作用。 Na()依赖性亮氨酸的摄取及其对L-NMA的抑制作用对pH值从6到9的变化不敏感。动力学分析表明L-NMA对Na()依赖性摄取的抑制作用揭示了一种非竞争性类型Ki值约为0.5 mM的抑制作用。
  • 【共振拉曼研究黄素细胞色素b2和L-乳酸单加氧酶的氧化和阴离子半醌形式。异别恶嗪环的结构和环境对黄素功能的影响。】 复制标题 收藏 收藏
    DOI:10.1021/bi962425x 复制DOI
    作者列表:Tegoni M,Gervais M,Desbois A
    BACKGROUND & AIMS: The oxidized and semiquinone anion radical forms of flavin mononucleotide carried by flavocytochrome b2 and L-lactate monooxygenase have been studied by resonance Raman (RR) spectroscopy. The RR spectra of their oxidized forms are compared with previously published RR data on various flavins and flavoproteins. Taking as a support available X-ray crystallographic data on flavoproteins, we have found correlations between the frequencies of RR bands II (1575-1588 cm-1), III (1534-1557 cm-1), and X (1244-1266 cm-1) and the H-bonding environment and/or the structure of the flavin ring. The present RR data provide strong evidence that the electron density, the conformation, and the H-bonding environment of the oxidized flavin mononucleotide of flavocytochrome b2 and L-lactate monooxygenase are different. As far as the anionic semiquinone form of flavoproteins is concerned, the behavior of two bands observed at 1280-1300 and 1320-1350 cm-1 suggests that they have vibrational origins similar to those of RR bands II and III of oxidized compounds. On this basis, the differences in conformation and H-bonding environment of the isoalloxazine ring, observed for the oxidized form of flavocytochrome b2 and L-lactate monooxygenase, appear to be preserved upon one-electron reduction of the flavin. For both flavoproteins, the RR spectra of the semiquinone form are affected by pyruvate binding. The data are interpreted in the frame of a change in H-bonding interaction of the C4&dbd;O carbonyl group of the flavin without significant alteration of the isoalloxazine conformation. This modification in electrostatic interaction quantitatively accounts for the pyruvate-induced changes of the oxidized/semiquinone and semiquinone/reduced redox potentials of the flavoproteins. Considering the high homology in the flavin catalytic sites of flavocytochrome b2 and L-lactate monooxygenase, the observed differences in H-bonding environment and conformation of the FMN ring are related to the different biological functions of the two flavoproteins.

    背景与目标: 通过共振拉曼光谱研究了黄素细胞色素b2和L-乳酸单加氧酶携带的黄素单核苷酸的氧化和半醌阴离子自由基形式。将其氧化形式的RR光谱与先前发表的有关各种黄素和黄素蛋白的RR数据进行比较。作为对黄素蛋白的可用X射线晶体学数据的支持,我们发现RR波段II(1575-1588 cm-1),III(1534-1557 cm-1)和X(1244-1266 cm)的频率之间存在相关性-1)和H键合环境和/或黄素环的结构。目前的RR数据提供了有力的证据,证明黄素细胞色素b2和L-乳酸单加氧酶的氧化黄素单核苷酸的电子密度,构象和H键环境不同。就黄素蛋白的阴离子半醌形式而言,在1280-1300和1320-1350 cm-1处观察到的两个谱带的行为表明,它们的振动起源与氧化化合物的RR谱带II和III相似。在此基础上,对黄素细胞色素b2和L-乳酸单加氧酶的氧化形式观察到的异恶嗪环的构象和H键环境的差异似乎在黄素的单电子还原中得以保留。对于两种黄素蛋白,丙酮酸结合都会影响半醌形式的RR光谱。在黄素的C 4 -O羰基的H键相互作用变化的框架内解释了数据,而异四恶嗪构象没有显着改变。静电相互作用的这种改变定量地解释了黄酮蛋白的丙酮酸诱导的氧化/半醌和半醌/还原的氧化还原电势的变化。考虑到黄素细胞色素b2和L-乳酸单加氧酶在黄素催化位点上的高度同源性,观察到的H键环境和FMN环构象的差异与两种黄素蛋白的不同生物学功能有关。

  • 【L-高半胱氨酸刺激[3H] MK-801与苯环利定识别位点的结合,因此是N-甲基-D-天冬氨酸操纵的阳离子通道的激动剂。】 复制标题 收藏 收藏
    DOI:10.1016/0306-4522(90)90204-h 复制DOI
    作者列表:Schwarz S,Zhou GZ,Katki AG,Rodbard D
    BACKGROUND & AIMS: :Rat brain synaptosomal membranes that are depleted of endogenous excitatory amino acids cannot bind [(+)-5-methyl-10, 11-dihydro-5H-dibenzo(a,d]cyclohept-5,10-imine maleate] ([3H]MK-801). However, they do so upon the restoration of excitatory amino acid agonists such as L-glutamate. [3H]MK-801 provides a molecular probe which is specific for a binding site located within the ionophore of the N-methyl-D-aspartate-type excitatory amino acid receptor, [3H]MK-801 does not bind to non-N-methyl-D-aspartate excitatory amino acid receptors. Exploiting [3H]MK-801 binding as a quantitative measure of agonist activity with respect to ability of inducing the open channel conformation, the present study demonstrates that L-homocysteate is an agonist almost equivalent to L-glutamate in terms of efficacy (maximal N-methyl-D-aspartate response) as well as potency (EC50). The effect of L-homocysteate was dose-dependent, stereospecific (L-homocysteate greater than DL-homocysteate greater than D-homocysteate), suppressible by the N-methyl-D-aspartate-selective competitive antagonist (+/-)-3(2-carboxy-piperazine-4-yl)propyl-l-phosphonate, and potentiated by the N-methyl-D-aspartate-selective "allosteric" modulator glycine. The demonstrated inactivity of L-homocysteine (and virtually all naturally occurring, non-acidic amino acids) implies that the omega-sulphonic acid moiety is an acceptable substitute for the omega carboxyl group for activating the N-methyl-D-aspartate receptor. While the potency of L-homocysteate at N-methyl-D-aspartate receptors was by a factor of only 1.6 smaller than that of L-glutamate, the affinity of L-homocysteate for kainate-type excitatory amino acid receptors was approximately four-fold lower than that of L-glutamate.(ABSTRACT TRUNCATED AT 250 WORDS)
    背景与目标: :耗尽内源性兴奋性氨基酸的大鼠脑突触体膜不能结合[()-5-甲基-10,11-dihydro-5H-dibenzo(a,d] cyclohept-5,10-imine maleate]([3H] MK-801),但是它们是在兴奋性氨基酸激动剂(如L-谷氨酸)恢复后才这样做的。[3H] MK-801提供了一种分子探针,该探针对位于N-甲基离子载体上的结合位点具有特异性-D-天门冬氨酸型兴奋性氨基酸受体[3H] MK-801不与非N-甲基-D-天门冬氨酸兴奋性氨基酸受体结合利用[3H] MK-801结合作为激动剂活性的定量指标关于诱导开放通道构象的能力,本研究表明,在效率(最大N-甲基-D-天冬氨酸反应)和效力(EC50)方面,L-高半胱氨酸盐是一种激动剂,几乎等同于L-谷氨酸盐。 L-同型半胱氨酸的作用是剂量依赖性的,立体定向的(L-同型半胱氨酸大于DL-同型半胱氨酸大于D-同型半胱氨酸) (teate),可被N-甲基-D-天冬氨酸选择性竞争性拮抗剂(/-)-3(2-羧基-哌嗪-4-基)丙基-1-膦酸酯抑制,并被N-甲基-D-增强天冬氨酸选择性“变构”调节剂甘氨酸。 L-高半胱氨酸(和几乎所有天然存在的非酸性氨基酸)的无活性表明,ω-磺酸部分是可接受的ω-羧基取代基,用于活化N-甲基-D-天冬氨酸受体。虽然L-高半胱氨酸对N-甲基-D-天冬氨酸受体的效力仅比L-谷氨酸低1.6倍,但L-高半胱氨酸对海藻酸盐型兴奋性氨基酸受体的亲和力约为四倍低于L-谷氨酸(摘要截短250字)
  • 【酿酒酵母MPR1基因的编码N-乙酰基转移酶表达在鲁氏酵母中赋予了对L-氮杂环丁烷-2-羧酸盐的抗性。】 复制标题 收藏 收藏
    DOI:10.1007/BF02932123 复制DOI
    作者列表:Pribylová L,Sychrová H
    BACKGROUND & AIMS: :The osmotolerant yeast Zygosaccharomyces rouxii is sensitive to the toxic L-proline analogue, L-azetidine-2-carboxylate (AZC). The possibility of use of the Saccharomyces cerevisiae MPR1 gene (ScMPR1) encoding the AZC-detoxifying enzyme as a dominant selection marker in Z. rouxii was examined. The heterologous expression of ScMPR1 in two Z. rouxii strains resulted in AZC-resistant colonies, but that of ScMPR1 as a dominant marker gene in vectors was affected by a high frequency of spontaneously resistant colonies. The same was found for an AZC-sensitive S. cerevisiae strain in which the ScMPR1 was expressed. In both yeasts, ScMPR1 can be used only as an auxiliary marker gene.
    背景与目标: 耐渗透酵母酵母Zygosaccharomyces rouxii对有毒的L-脯氨酸类似物L-氮杂环丁烷-2-羧酸盐(AZC)敏感。研究了将酿酒酵母酿酒酵母MPR1基因(ScMPR1)编码为AZC解毒酶作为鲁氏沼虾的主要选择标记的可能性。 ScMPR1在两个鲁氏弧菌菌株中的异源表达导致了AZC抗性菌落,但作为载体中显性标记基因的ScMPR1的表达受到了高频率的自发抗性菌落的影响。对于其中表达ScMPR1的AZC敏感啤酒酵母菌株也发现了相同的情况。在两种酵母中,ScMPR1只能用作辅助标记基因。
  • 【顺铂释放到可生物降解的聚-d-l-乳酸中的控制释放。】 复制标题 收藏 收藏
    DOI: 复制DOI
    作者列表:Natsugoe S,Kumanohoso T,Tokuda K,Shimada M,Mueller J,Nakamura K,Yamada K,Fukuzaki H,Aikou T
    BACKGROUND & AIMS: Using a melt-pressing technique, we produced a small solid cylinder containing cisplatin (CDDP) embedded in poly-d, l-lactic acid (CDDP-PLA). The in vitro release of CDDP from the polymer was examined in an immersion system. CDDP was released continuously for more than four weeks with no initial burst. Drug distribution for CDDP-PLA was compared with CDDP solution (CDDP-SOL) by subcutaneous administration into the back of rats. In the CDDP-PLA group, a high concentration of CDDP was maintained in the subcutaneous tissues near the implants for 20 days. However, in the CDDP-SOL group, the concentration of CDDP was low by 10 days after drug administration. CDDP-PLA may become a useful tool in locoregional chemotherapy as a solid type of drug delivery system with longlasting release.

    背景与目标: 使用熔融压制技术,我们生产了一个小的固态圆筒,其中包含嵌入聚-d-L-乳酸(CDDP-PLA)中的顺铂(CDDP)。在浸没系统中检查了CDDP从聚合物中的体外释放。 CDDP连续释放了四个多星期,没有最初的爆发。通过向大鼠背部皮下给药,将CDDP-PLA的药物分布与CDDP溶液(CDDP-SOL)进行比较。在CDDP-PLA组中,在植入物附近的皮下组织中维持高浓度的CDDP达20天。但是,在CDDP-SOL组中,给药后10天CDDP的浓度低。 CDDP-PLA作为局部释放持久释放的固体药物传递系统,可能成为局部化疗的有用工具。

  • 【连续左旋肉碱生产过程中转基因大肠杆菌菌株的质粒维持和生理学。】 复制标题 收藏 收藏
    DOI:10.1007/s10529-007-9432-4 复制DOI
    作者列表:Bernal V,González-Veracruz M,Cánovas M,Iborra JL
    BACKGROUND & AIMS: :The effect of immobilization on cell physiology and how this determines cell metabolic performance is an important concern for developing bioprocess. This is particularly true for genetically modified microorganisms and their genetic stability. For this reason the stability and physiological state of plasmid-bearing E. coli cells were ascertained by flow cytometry. Differences in the cellular DNA and protein content (15-20%) permit discrimination of control and plasmid-bearing cells, as well as adaptation to continuous cultivation conditions in both freely suspended and immobilized states to be monitored. Moreover, the observed metabolic burden due to maintenance and over-expression of plasmid-coded genetic material and slow cell growth in poorly-viable immobilized cells were found to be the main factors contributing to strain stabilization.
    背景与目标: :固定化对细胞生理的影响以及如何决定细胞代谢性能是发展生物过程的重要考虑因素。对于转基因微生物及其遗传稳定性尤其如此。因此,通过流式细胞术确定了带有质粒的大肠杆菌细胞的稳定性和生理状态。细胞DNA和蛋白质含量的差异(15-20%)可以区分对照细胞和带有质粒的细胞,并可以监测自由悬浮和固定状态下连续培养条件的适应性。此外,已发现由于质粒编码的遗传物质的维持和过表达以及在存活率低的固定化细胞中缓慢的细胞生长而导致的观察到的代谢负担是促成菌株稳定的主要因素。
  • 【大麦(Hordeum vulgar L.)抗寒成分的遗传分析。】 复制标题 收藏 收藏
    DOI: 复制DOI
    作者列表:Karsai I,Mészáros K,Bedó Z,Hayes PM,Pan A,Chen F
    BACKGROUND & AIMS: Winterhardiness in cereals is the consequence of a number of complex and interacting componentscold tolerance, vernalization requirement and photoperiod sensitivity. An understanding of the genetic basis of these component traits should allow for more effective selection. Genome map-based analyses hold considerable promise for dissecting complex phenotypes. A 74-point linkage map was developed from one hundred double haploid lines derived from a winter x spring barley cross and used as the basis for quantitative trait locus (QTL) analyses to determine the chromosome location of genes controlling components of winterhardiness. Despite the greater genome coverage provided by the current map, a previously-reported interval on chromosome 7 remains the only region where significant QTL effects for winter survival were detected in this population. QTLs for heading date under 24 h light map to the same region. A QTL for heading date under this photoperiod regime also maps to chromosome 2. A distinct set of QTLs mapping to chromosomes 1, 2, 3 and 5 determined heading date under 8 h light. Patterns of differential QTL expression underscore the complexity of Winterhardiness.

    背景与目标: 谷物的耐寒性是许多复杂且相互作用的成分的结果,包括耐寒性,春化要求和光周期敏感性。对这些成分性状的遗传基础的了解应有助于更有效的选择。基于基因组图谱的分析在解剖复杂表型方面具有广阔的前景。用一百个来自冬季x春季大麦杂交的双单倍体系构建了74点连锁图谱,并将其用作定量性状基因座(QTL)分析的基础,以确定控制耐寒性成分的基因的染色体位置。尽管当前图谱提供了更大的基因组覆盖范围,但先前在7号染色体上报告的间隔仍然是在该种群中检测到对冬季存活具有显着QTL影响的唯一区域。在24小时光照下朝向日期的QTL映射到同一区域。在此光周期条件下,抽穗期的QTL也映射到染色体2。在8 h光照下,映射到染色体1、2、3和5的一组独特的QTL确定了抽穗期。 QTL差异表达模式强调了耐寒性的复杂性。

  • 【番木瓜脂肪酶间歇性开放反应模式生物合成(S)-萘普生淀粉酯。】 复制标题 收藏 收藏
    DOI: 复制DOI
    作者列表:Wang Y,Xin JY,Li QH,Sun LR,Xia CG
    BACKGROUND & AIMS: :Inorder to brought S-naproxen into small intestine, an optically pure (S)-naproxen starch ester was produced by lipase through enantio-selective trans-esterification of racemic naproxen methyl ester with pretreatment starch in solvent system. With carefully selection of the reaction medium (isooctane), lipase (Carica Papaya Lipase, CPL) and the reaction mode (intermittent opening), a high conversion rate (48.6%) and enantiomeric excess of product (99.6%) was obtained. The slow release macromolecular (S)-Naproxen had been synthesized to improve the efficacy of racemic naproxen and overcome its side effects. The enanitomeric ratio of CPL (E=52.5) was higher than CRL (E=22) and greatly influenced by the byproduct methyl alcohol. The intermittent opening reaction mode was the effective way to remove the inhibition of methyl alcohol and to improve the enantio-selectivity of CPL. S-naproxen starch was confirmed by HPLC and 1H NMR. This method may also apply to preparation the other optically pure 2-phenylpropionic acid derivatives. S-naproxen starch was a new optically pure derivatives possessing emulsifying and slow release properties would be widely applied to the food, pharmaceutical and biomedical industries.
    背景与目标: :为了使S-萘普生进入小肠,在溶剂体系中,脂肪酶通过外消旋萘普生甲酯与淀粉的预处理将外消旋萘普生甲酯进行对映选择性酯交换反应,制得了光学纯的(S)-萘普生淀粉酯。通过仔细选择反应介质(异辛烷),脂肪酶(番木瓜脂肪酶,CPL)和反应模式(间歇打开),可获得高转化率(48.6%)和对映体过量的产物(99.6%)。已经合成了缓释大分子(S)-萘普生,以提高外消旋萘普生的功效并克服其副作用。 CPL(E = 52.5)的对映体比率高于CRL(E = 22),并受到副产物甲醇的很大影响。间歇性开放反应模式是消除甲醇抑制作用,提高CPL对映选择性的有效途径。 S-萘普生淀粉通过HPLC和1H NMR确认。该方法还可以用于制备其他光学纯的2-苯基丙酸衍生物。 S-萘普生淀粉是一种具有乳化和缓释性能的新型光学纯衍生物,将被广泛应用于食品,制药和生物医学行业。
  • 【茄茄花药培养中的愈伤组织形成和器官发生。】 复制标题 收藏 收藏
    DOI:10.1016/S0176-1617(84)80029-2 复制DOI
    作者列表:Reynolds TL
    BACKGROUND & AIMS: :In anther cultures of Solanum carolinense L., Murashige and Skoog's medium (MS) supplemented with 2.2 mg · l(-1) 2,4-dichlorophenoxyacetic acid (2,4-D) and 6.0 mg · l(-1) kinetin (KIN) served as callus induction medium. Cytological observations confirmed that the callus originated from pollen grains. Upon transfer to medium lacking 2,4-D, callus cultures regenerated shoots exclusively. However, maximum efficiency in regeneration occurred only after callus had been maintained in the presence of 2,4-D for a minimum of 12 weeks. Callus younger than this or older than 16 weeks showed a significant decline in organogenic competence when transferred to the appropriate medium. It is suggested that 2,4-D may establish a transitory potential for regeneration in pollen-derived callus cultures but must be removed before this potential can be expressed.
    背景与目标: :在茄茄的花药培养中,Murashige和Skoog培养基(MS)补充了2.2 mg·l(-1)2,4-二氯苯氧基乙酸(2,4-D)和6.0 mg·l(-1)激动素(KIN)用作愈伤组织诱导培养基。细胞学观察证实愈伤组织起源于花粉粒。转移到缺乏2,4-D的培养基后,愈伤组织培养物专门再生芽。但是,只有在2,4-D存在下保持愈伤组织至少12周之后,再生的最大效率才会出现。小于此年龄或大于16周的愈伤组织转移到适当的培养基中后,其器官发生能力显着下降。建议2,4-D可能在花粉衍生的愈伤组织培养中建立一个短暂的再生潜能,但在表达该潜能之前必须将其除去。
  • 【银杏叶和牛痘越桔的提取物可防止低密度脂蛋白胆固醇的光诱导氧化。】 复制标题 收藏 收藏
    DOI:10.1016/S0944-7113(97)80006-2 复制DOI
    作者列表:Rasetti MF,Caruso D,Galli G,Bosisio E
    BACKGROUND & AIMS: :Oxidation of low density lipoproteins (LDL) favours cholesterol loading in macrophages and formation of "foam cells", typical of the early atheroma lesions. LDL cholesterol oxidation generates oxysterols, extremely cytotoxic molecular species with diverse biological activities. Vegetable polyphenols are dietary components of pharmacological interest for their anti-oxidant properties. Ginkgo biloba L. (Gingkoaceae) leaves and Vaccinium myrtillus L. (Ericaceae) fruits are known for their beneficial effects in the treatment of various diseases involving free radicals and oxidative damage to biological lipids. In this study we investigated the effect of Ginkgo biloba L. and Vaccinium myrtillus L. extracts on the formation of cholesterol oxides during the photo induced oxidation of human LDL. The results demonstrate a concentration dependent inhibition of oxysterol formation in the presence of both extracts. Protection against oxidation was confirmed by the partial restoration of the normal electrophoretic mobility of LDL, which has been influenced by the UV irradiation. These effects extend knowledge of the therapeutic action of Ginkgo biloba L. and Vaccinium myrtillus L. as agents in anti-atherosclerotic regimens.
    背景与目标: 低密度脂蛋白(LDL)的氧化有助于巨噬细胞中的胆固醇负载和形成“泡沫细胞”,这是早期动脉粥样硬化病变的典型表现。 LDL胆固醇的氧化产生氧固醇,这是具有多种生物活性的极具细胞毒性的分子物种。植物多酚因其抗氧化性能而成为具有药理学意义的饮食成分。银杏叶(Gingkoaceae)叶和牛痘越橘(Ericaceae)水果因其在治疗多种疾病中的有益作用而广为人知,这些疾病涉及自由基和对生物脂质的氧化损伤。在这项研究中,我们研究了银杏叶提取物和牛痘越桔提取物在光诱导人LDL氧化过程中对胆固醇氧化物形成的影响。结果表明在两种提取物存在下,浓度依赖性抑制氧固醇的形成。 LDL的正常电泳迁移率已部分恢复,这证实了抗氧化的作用,该迁移率已受到紫外线辐射的影响。这些作用扩展了银杏叶和越桔越桔作为抗动脉粥样硬化治疗剂的治疗作用的知识。
  • 【贝叶斯网络说明了玉米(Zea mays L.)中的基因组和残留性状联系。】 复制标题 收藏 收藏
    DOI:10.1534/g3.117.044263 复制DOI
    作者列表:Töpner K,Rosa GJM,Gianola D,Schön CC
    BACKGROUND & AIMS: :Relationships among traits were investigated on the genomic and residual levels using novel methodology. This included inference on these relationships via Bayesian networks and an assessment of the networks with structural equation models. The methodology employed three steps. First, a Bayesian multiple-trait Gaussian model was fitted to the data to decompose phenotypic values into their genomic and residual components. Second, genomic and residual network structures among traits were learned from estimates of these two components. Network learning was performed using six different algorithmic settings for comparison, of which two were score-based and four were constraint-based approaches. Third, structural equation model analyses ranked the networks in terms of goodness of fit and predictive ability, and compared them with the standard multiple-trait fully recursive network. The methodology was applied to experimental data representing the European heterotic maize pools Dent and Flint (Zea mays L.). Inferences on genomic and residual trait connections were depicted separately as directed acyclic graphs. These graphs provide information beyond mere pairwise genetic or residual associations between traits, illustrating for example conditional independencies and hinting at potential causal links among traits. Network analysis suggested some genetic correlations as potentially spurious. Genomic and residual networks were compared between Dent and Flint.
    背景与目标: :使用新颖的方法,在基因组和残基水平上研究了性状之间的关系。这包括通过贝叶斯网络推断这些关系,以及使用结构方程模型评估网络。该方法采用三个步骤。首先,将贝叶斯多特征高斯模型拟合到数据中,以将表型值分解为它们的基因组和残差成分。其次,从这两个组成部分的估计中了解了性状之间的基因组和残留网络结构。使用六种不同的算法设置进行网络学习进行比较,其中两种基于得分,四种基于约束。第三,结构方程模型分析根据拟合优度和预测能力对网络进行排名,并将其与标准的多特征完全递归网络进行比较。将该方法应用于代表欧洲杂种玉米库Dent和Flint(Zea mays L.)的实验数据。关于基因组和残留性状联系的推论分别被描述为有向无环图。这些图提供了性状之间仅成对的遗传或残差关联之外的信息,举例说明了条件独立性,并暗示了性状之间的潜在因果关系。网络分析表明某些遗传相关性可能是虚假的。比较了Dent和Flint之间的基因组网络和残差网络。
  • 【多年生黑麦草(Lolium perenne L.)编码果糖:果糖6G-果糖基转移酶(6G-FFT)/果糖:果糖1-果糖基转移酶(1-FFT)的cDNA的分子和功能表征。】 复制标题 收藏 收藏
    DOI:10.1093/jxb/erl034 复制DOI
    作者列表:Lasseur B,Lothier J,Djoumad A,De Coninck B,Smeekens S,Van Laere A,Morvan-Bertrand A,Van den Ende W,Prud'homme MP
    BACKGROUND & AIMS: :Fructans are the main storage compound in Lolium perenne. To account for the prevailing neokestose-based fructan synthesis in this species, a cDNA library of L. perenne was screened by using the onion (Allium cepa) fructan:fructan 6G-fructosyltransferase (6G-FFT) as a probe. A full length Lp6G-FFT clone was isolated with significant homologies to vacuolar type fructosyltransferases and invertases. The functionality of the cDNA was tested by heterologous expression in Pichia pastoris. The recombinant protein demonstrated both 6G-FFT and fructan:fructan 1-fructosyltransferase activities (1-FFT) with a maximum 6G-FFT/1-FFT ratio of two. The activity of 6G-FFT was investigated with respect to developmental stage, tissue distribution, and alterations in carbohydrate status expression and compared to sucrose:sucrose 1-fructosyltransferase (1-SST). Lp6G-FFT and Lp1-SST were predominantly expressed in the basal part of elongating leaves and leaf sheaths. Expression of both genes declined along the leaf axis, in parallel with the spatial occurrence of fructan and fructosyltransferase activities. Surprisingly, Lp6G-FFT was highly expressed in photosynthetically active tissues where very low extractable fructosyltransferase activity and fructan amounts were detected, suggesting a post-transcriptional regulation of expression. Lp6G-FFT gene expression increased only in elongating leaves following similar increases of sucrose content in blades, sheaths, and elongating leaf bases. Regulation of Lp6G-FFT gene expression depends on the tissue according to its sink-source status.
    背景与目标: :果聚糖是黑麦草的主要贮藏化合物。为了说明该物种中普遍存在的基于新核糖的果聚糖合成,使用洋葱(葱属)果聚糖:果聚糖6G-果糖基转移酶(6G-FFT)作为探针筛选了紫苏乳酸杆菌的cDNA文库。分离出全长Lp6G-FFT克隆,与液泡型果糖基转移酶和转化酶具有显着同源性。通过在毕赤酵母中的异源表达来测试cDNA的功能。重组蛋白同时具有6G-FFT和果聚糖:果聚糖1-果糖基转移酶活性(1-FFT),最大6G-FFT / 1-FFT比率为2。研究了6G-FFT的活性,涉及发育阶段,组织分布和碳水化合物状态表达的变化,并与蔗糖:蔗糖1-果糖基转移酶(1-SST)进行了比较。 Lp6G-FFT和Lp1-SST主要在伸长的叶和叶鞘的基部表达。两种基因的表达沿叶轴下降,与果聚糖和果糖基转移酶活性的空间发生平行。出人意料的是,Lp6G-FFT在光合作用活跃的组织中高表达,在该组织中检测到极低的果糖基转移酶活性和果聚糖含量,表明转录后的表达调控。 Lp6G-FFT基因表达仅在叶片,鞘和叶片基部中蔗糖含量的相似增加之后才在叶片中增加。 Lp6G-FFT基因表达的调节取决于组织的汇源状态。

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