马尾松GOT、LDH和MDH同工酶的遗传方式和连锁关系

本文采用聚丙烯酰胺凝胶电泳研究了马尾松三种同工酶的遗传方式和连锁关系。结果表明,GOT、LDH和MDH三种同工酶的遗传表达稳定,分别受4个、2个和4个位点控制。只有一对位点(MDH-3和MDH-4)间存在着紧密的连锁关系。     

Contrasting the Pb (II) and Cd (II) tolerance of Enterobacter sp. via its cellular stress responses

Successful application of microorganisms to heavy metal remediation depends on their resistance to toxic metals. This study contrasted the differences of tolerant mechanisms between Pb²⁺ and Cd²⁺ in Enterobacter sp. Microbial respiration and production of formic acid showed that Enterobacter sp. had a higher tolerant concentration of Pb (>1000 mg l⁻¹) than Cd (about 200 mg l⁻¹). Additionally, SEM confirmed that most of Pb and Cd nanoparticles (NPs) were adsorbed onto cell membrane. The Cd stress, even at low concentration (50 mg l⁻¹), significantly enlarged the sizes of cells. The cellular size raised from 0.4 × 1.0 to 0.9 × 1.6 μm on average, inducing a platelet-like shape. In contrast, Pb cations did not stimulate such enlargement even up to 1000 mg l⁻¹. Moreover, Cd NPs were adsorbed homogeneously by almost all the bacterial cells under TEM. However, only a few cells work as ‘hot spots’ on the sorption of Pb NPs. The heterogeneous sorption might result from a ‘self-sacrifice’ mechanism, i.e., some cells at a special life stage contributed mostly to Pb sorption. This mechanism, together with the lower mobility of Pb cations, caused higher microbial tolerance and removal efficiency towards Pb²⁺. This study sheds evident contrasts of bacterial resistance to the two most common heavy metals.     

Single dose of synthetic microRNA-199a or microRNA-149 mimic does not improve cardiac function in a murine model of myocardial infarction

Molecular and Cellular Biochemistry - Intramyocardial injection of synthetic microRNAs (miRs) has recently been reported to be beneficial after myocardial infarction (MI). We conducted a randomized...     

BALB／c小鼠胚胎干细胞系的建立及其嵌合体小鼠的获得

目的：建立BALB/c小鼠胚胎干细胞系,并用于制作嵌合体小鼠。方法：从BALB／c小鼠囊胚内分离培养内细胞团块。建系后,进行C57BL／6L小鼠受体囊胚腔注射,制作嵌合体小鼠,结果：建立了我国第一株BALB／c小鼠胚胎干细胞系,该细胞系具有典型的ES细胞形态,碱性磷酸酶强阳性,核型正常以及具有分化为三种胚层组织的能力,并已产生5只嵌合体小鼠,结论：建立的BALB／c小鼠胚胎干细胞系具有胚胎干细胞的各种特点,可用于体内外诱导分化研究,在进一步观察生殖系嵌合情况后,决定是否可应用于基因打靶等转基因动物的制作。     

Characterization of a novel β-thioglucosidase CpTGG1 in Carica papaya and its substrate-dependent and ascorbic acid-independent O-β-glucosidase activity

Plant thioglucosidases are the only known S-glycosidases in the large superfamily of glycosidases.These enzymes evolved more recently and are distributed mainly in Brassicales.Thioglucosidase research has focused mainly on the cruciferous crops due to their economic importance and cancer preventive benefits.In this study,we cloned a novel myrosinase gene,CpTGG1,from Carica papaya Linnaeus.and showed that it was expressed in the aboveground tissues in planta.The recombinant CpTGG1 expressed in Pichia pastoris catalyzed the hydrolysis of both sinigrin and glucotropaeolin(the only thioglucoside present in papaya),showing that CpTGG1 was indeed a functional myrosinase gene.Sequence alignment analysis indicated that CpTGG1 contained all the motifs conserved in functional myrosinases from crucifers,except for two aglycon-binding motifs,suggesting substrate priority variation of the non-cruciferous myrosinases.Using sinigrin as substrate,the apparent Km and Vmax values of recombinant CpTGG1 were 2.82 mM and 59.9 μmol min-1 mg protein-1,respectively.The Kcat IKm value was 23 s-1 mM-1.O-β-glucosidase activity towards a variety of substrates were tested,CpTGG1 displayed substrate-dependent and ascorbic acid-independent O-β-glucosidase activity towards 2-nitrophenyl-βD-glucopyranoside and 4-nitrophenyl-β-D-glucopyranoside,but was inactive towards glucovanillin and n-octyl-β-D-glucopyranoside.Phylogenetic analysis indicated CpTGG1 belongs to the MYR II subfamily of myrosinases.     

獐牙菜属植物花蜜腺形态及解剖学

在扫描电镜下观察了獐牙菜属Swertia L.10组30种植物花蜜腺的数目,位置,形态和附属物等特征;同时还利用光镜对各组代表种的蜜腺结构进行了解剖学观察。结果表明獐牙菜属花蜜腺外部形态多种多,但在组与组之间无明显间断,演化序列呈梯度变化;内部结构基本相同,为不具维管束的结构蜜腺,且均为淀粉型蜜腺。因此,从花蜜腺的角度不支持将獐牙菜属划分为小属的观点,同时,还结合其它证据讨论了花蜜腺特征的演化趋势。