Degradable rosin-ester-caprolactone graft copolymers

We have carried out the synthesis of side-chain rosin-ester-structured poly(ε-caprolactone) (PCL) through a combination of ring-opening polymerization and click chemistry. Rosin structures are shown to be effectively incorporated into each repeat unit of caprolactone. This simple and versatile methodology does not require sophisticated purification of raw renewable biomass from nature. The rosin properties have been successfully imparted to the PCL polymers. The bulky hydrophenanthrene group of rosin increases the glass-transition temperature of PCL by >100 °C, whereas the hydrocarbon nature of rosin structures provides PCL excellent hydrophobicity with contact angle very similar to polystyrene and very low water uptake. The rosin-containing PCL graft copolymers exhibit full degradability and good biocompatibility. This study illustrates a general strategy to prepare a new class of renewable hydrocarbon-rich degradable biopolymers.     

OsAM1 is required for leptotene-zygotene transition in rice

The events occurring at the onset of meiosis have not been fully elucidated. In the present study, OsAM1 was identified in rice (Oryza sativa L.) by map-based cloning. OsAM1, a homolog of Arabidopsis SWI1 and maize AM1, encodes a protein with a coiled-coil domain in its central region. In the Osam1 mutant, pollen mother cells are arrested at leptotene, showing that OsAM1 is required for the leptotene-zygotene transition. Immunocytological analysis revealed that OsAM1 exists as foci in early prophase I meiocytes. Very faint OsREC8 foci persisted in the Osam1 mutant, indicating that OsAM1 is not required for the initial meiotic recruitment of OsREC8. In the absence of OsAM1, many other critical meiotic components, including PAIR2, ZEP1 and OsMER3, could not be correctly installed onto chromosomes. In contrast, in pair2, Osmer3 and zep1 mutants, OsAM1 could be loaded normally, suggesting that OsAM1 plays a fundamental role in building the proper chromosome structure at the beginning of meiosis.     

抑癌基因XEDAR的研究进展

X-连锁性外胚层发育不良受体（X-linked ectodermal dysplasia receptor, XEDAR ）基因位于人类染色体Xq12,编码的蛋白XEDAR作为新近分离出来的肿瘤坏死因子受体家族成员其功能主要涉及细胞增殖、参与细胞分化（胚胎的发育,表皮的分化）、调亡等。XEDAR已在多种肿瘤组织中研究,笔者就其基本概念及在肿瘤研究方面的进展进行综述。     

结核杆菌Hsp65与人IL-2融合蛋白在耻垢杆菌表达

目的：构建能够分泌表达结核分枝杆菌热休克蛋白65（Hsp65）与人IL-2融合蛋白的重组耻垢分枝杆菌（recombinant Mycobacterium Smegmatis,rMs）。方法：用EcoRV和HindIII双酶切含Hsp65．IL-2融合基因的pPRO-hsp65-IL-2载体,回收目的基因片断Hsp65-IL-2,并将其亚克隆入同样双酶切的大肠埃希菌-分枝杆菌穿梭分泌表达载体pDE22中。重组质粒pDE22-hsp65-IL-2酶切鉴定正确后,电穿孔转化MS感受态,潮霉素抗性压力筛选阳性rMs。Westem—blot鉴定rMs培养上清蛋白中目的蛋白的表达。结果：重组pDE22-hsp65-IL-2质粒酶切后可获得约2000bp片段,与预期大小一致。Western-blot结果表明,rMs培养上清蛋白中有特异性反应条带,大小为78kD,与Hsp65-IL-2融合蛋白大小相一致。结论：成功构建了大肠埃希菌．分枝杆菌穿梭分泌表达载体pDE22-hsp65-IL-2,为该rMs的免疫学特性及抗结核分枝杆菌感染的保护效果研究奠定了基础。     

抑癌基因XEDAR 的研究进展

X-连锁性外胚层发育不良受体(X-linked ectodermal dysplasia receptor,XEDAR)基因位于人类染色体Xq12,编码的蛋白XEDAR作为新近分离出来的肿瘤坏死因子受体家族成员其功能主要涉及细胞增殖、参与细胞分化(胚胎的发育,表皮的分化)、调亡等。XEDAR已在多种肿瘤组织中研究,笔者就其基本概念及在肿瘤研究方面的进展进行综述。     

关于iFlora核心数据建设中的一些思考

物种是iFlora数据采集的基本对象,但我们面临的植物是一个庞大、复杂的体系,没有正确的分类认识和物种鉴定方法,就不能保证iFlora的准确构建。目前植物中存在着不少数量的疑难种、争议种．已定种分类界限的准确性以及复杂的种下分类单位,都给iFlora的构建带来了较大的问题。本文以作者近年来研究的薯蓣科（Dioscoreaceae）薯蓣属（DioscoreaL．）、蓼科（Polygonaceae）何首乌（PolygonummM虹orumThuna．）、唇形科（Lamiaceae）夏枯草属（PrunellaL．）等为主要例子．对iFlora核心数据中的DNA条形码信息及基础数据中形态学分类信息的建设提出几点思考。重点提出,关注物种尤其是广布种。由于其分布范围广泛,在不同分布区个体常表现出连续变化特征,而实际工作中往往会出现忽略连续变化特征而把1个种在分布区端点的居群鉴定为不同种的问题;因此应关注种的居群DNA条形码的变异幅度。     

First-principle study of the native defects in GaAs saturable absorbers

The change of atom configuration in GaAs, caused by intrinsic point defects (Ga and As vacancies, Ga and As antisites, Ga and As interstitials), is first calculated by a plane wave pseudo-potential method with the generalised gradient approximation in the frame of density functional theory, and the most stable structure is obtained. Then, the formation energy of each kind of the native defect is calculated, by which the possibilities of the six kinds of point defects to be formed during crystal growth are analysed. The defect energy levels corresponding to each kind of the native point defect and their electron occupancy are analysed from the aspect of density of states. Finally, the elastic constants of GaAs saturable absorbers with native point defects are calculated, and the impacts on the elastic properties brought by native point defects are studied. The values of defect energy levels obtained will be helpful in ascertaining the mechanism of the EL2 deep level in the GaAs saturable absorber, and the analysis of the elastic properties of a GaAs crystal with native point defects will be helpful in guiding the application of the GaAs crystal as a saturable absorber in passively Q-switched lasers.     

十字花科植物FAE1基因的克隆与功能验证

对十字花科(Brassicaceae)植物非洲芥菜(Brassica tournefortii Gouan)、埃塞俄比亚芥(B.carinataA.Braun)、短喙芥(B.elongata Ehrhart)、芝麻菜[Eruca vesicaria subsp.sativa(Miller) Thellung]、野萝卜(Raphanus raphanistrum Linn.)、Crambe filiformis Jacq.、菥蓂(Thlaspi arvense Linn.)、臭荠[Coronopus didymus (Linn.) Smith]、荠[Capsella bursa-pastoris(Linn.) Medikus]和小花碎米荠(Cardamine parviflora Linn.)的FAE1基因进行了克隆、序列比对及功能验证.结果显示:上述前6种1亚种的FAE1基因长度均为1 521 bp,臭荠的FAE1基因长度为1 517 bp,荠和小花碎米荠的FAE1基因长度为1 518 bp,GenBank登录号为JX898749-JX898758;它们的序列相似性较高,相似度达89％;对位排列矩阵长度1 521 bp,其中包含保守位点1 051个(69.1％)、变异位点470个(30.9％)和简约信息位点232个(15.3％);臭荠、荠和小花碎米荠的FAE1序列在第132位分别缺失3个碱基,臭荠的FAE1基因在第515位缺失1个碱基.虽然荠和小花碎米荠的FAE1基因编码505个氨基酸、臭荠的FAE1基因仅编码186个氨基酸、其他种类的FAE1基因均编码506个氨基酸,但它们的氨基酸序列相似度高达88.9％;各种类的氨基酸序列存在151个变异位点,其中有6个变异位点与种子芥酸含量相关.Western blot及气相色谱分析结果表明:各种类的FAE1基因在酵母中均能表达出预期的蛋白产物;在臭荠和小花碎米荠FAE1基因的转化酵母细胞中无芥酸积累,而在其他种类FAE1基因的转化酵母细胞中均有芥酸积累;此外,除荠外的其他8种1亚种植物的种子芥酸含量与转化酵母细胞中的芥酸含量正相关.     

Ploidy variation in Buddleja L. (Buddlejaceae) in the Sino-Himalayan region and its biogeographical implications

The chromosome numbers of 27 populations of Buddleja , comprising 14 species, were counted. The basic chromosome number of all species was x  = 19, confirming previous reports. Different ploidy levels (2 n  = 38, 76, 114, 228) were observed in these taxa, representing diploids, tetraploids, hexaploids, and dodecaploids, respectively. The chromosome numbers of B. yunnanensis , B. brachystachya , and B. macrostachya are reported for the first time. The tetraploid 2 n  = 76 is a new ploidy level for B. myriantha . Particular attention was given to B. macrostachya , because of the variation in morphology and ploidy level between isolated populations of this species. Two types of interphase nuclei were recognized: the complex chromocentre type in B. macrostachya and the simple chromocentre type in the other species. Biogeographically, most of the polyploidy in the Asiatic species occurs in the Sino-Himalayan region. It seems to be associated with the uplift of the Himalayan Mountains, the orogeny of this region playing an important role in the evolution of polyploidy in these taxa.  © 2007 The Linnean Society of London. Botanical Journal of the Linnean Society , 2007, 154 , 305–312.     

Erratum to: Rapid generation of genetic diversity by multiplex CRISPR/Cas9 genome editing in rice

正The same figure was misused for the PCR/RE assay results of Gn1a and GW2 fragments in Figure 3, and the arrows in the graphicsal result of GW2 were not on the tape. The corrected Figure 3 is as follows.