Nisin对幽门螺杆菌生物学作用的实验研究

目的：探讨乳链菌肽（Nisin)在柠檬酸的协同作用下对幽门螺杆菌（Helicobacter pylori,Hp)的生物学作用,寻求一种新的防治Hp微生态制剂,为临床治疗Hp提供理论和实践指导。方法：运用国际通用的药敏试验方法纸片法（Kirby-Bauer)和倾注培养法（Pour Culture)对96例从胃病患者分离出的临床株Nisin和柠檬酸协同作用的生物学实验,然后电镜观察被Nisin作用后的Hp菌株细胞结构并进行分析处理。结果：Nisin在柠檬酸的协同作用下对Hp具有明显的抑杀作用,电镜观察被作用后的Hp菌株细胞质膜破碎和细胞发生球形样变。结论：Nisin作用机制主要表现在对Hp菌株的细胞质膜上。     

Immune-deficient mouse models for analysis of human stem cells

The field of murine models of xenotransplantation has grown immensely over the past two decades. The explosive growth in this field is in part due to the fact that good in vitro methods do not exist yet to allow examination of human stem cell homing into the bone marrow compartment versus other tissues, long-term survival of human stem cells, or differentiation into tissues outside of the hematopoietic system. Since these important aspects of human stem cell biology can be examined in vivo using immune-deficient mice, the number of different strains and models is constantly increasing. The current review discusses the merits and drawbacks of each immune-deficient mouse xenograft system as it stands to date and reviews how each immune-deficient mouse model has been used to further our knowledge of human hematopoietic stem cell biology.     

Tonoplast intrinsic protein isoforms as markers for vacuolar functions

Plant cell vacuoles may have storage or lytic functions, but biochemical markers specific for the tonoplasts of functionally distinct vacuoles are poorly defined. Here, we use antipeptide antibodies specific for the tonoplast intrinsic proteins alpha-TIP, gamma-TIP, and delta-TIP in confocal immunofluorescence experiments to test the hypothesis that different TIP isoforms may define different vacuole functions. Organelles labeled with these antibodies were also labeled with antipyrophosphatase antibodies, demonstrating that regardless of their size, they had the expected characteristics of vacuoles. Our results demonstrate that the storage vacuole tonoplast contains delta-TIP, protein storage vacuoles containing seed-type storage proteins are marked by alpha- and delta- or alpha- and delta- plus gamma-TIP, whereas vacuoles storing vegetative storage proteins and pigments are marked by delta-TIP alone or delta- plus gamma-TIP. In contrast, those marked by gamma-TIP alone have characteristics of lytic vacuoles, and results from other researchers indicate that alpha-TIP alone is a marker for autophagic vacuoles. In root tips, relatively undifferentiated cells that contain vacuoles labeled separately for each of the three TIPs have been identified. These results argue that plant cells have the ability to generate and maintain three separate vacuole organelles, with each being marked by a different TIP, and that the functional diversity of the vacuolar system may be generated from different combinations of the three basic types.     

Morphophysiological dormancy in seeds of the ANA grade angiosperm Schisandra arisanensis (Schisandraceae)

We determined the kind of seed dormancy in Schisandra arisanensis, an ANA grade ([A]mborellales [N]ymphaeales [A]ustrobaileyales) angiosperm with medicinal value. Seeds have small underdeveloped embryos, and following seed maturity their length increased approximately 360% before radicle emergence. Germination was delayed 6–8 weeks, and the percentage and rate were much higher at 15/6, 20/10 and 25/15°C than at 30/20°C. For seeds incubated at 5/5°C (8 weeks) → 15/6°C (4 weeks) → 20/10°C (8 weeks) → 25/15°C (12 weeks) → 20/10°C (5 weeks), embryos grew at 15/6°C → 20/10°C, and almost all seeds that germinated (89%) did so at 20/10°C → 25/15°C. When seeds were incubated in a complementary temperature sequence, 25/15°C (12 weeks) → 20/10°C (8 weeks) → 15/6°C (4 weeks) → 5/5°C (9 weeks) → 15/6°C (4 weeks), embryos grew at 25/15°C → 20/10°C. Nearly all seeds that germinated (93%) did so at 25/15°C → 20/10°C and at 15/6°C following 9 weeks at 5/5°C. Based on the temperature requirements for embryo growth and seed germination, seeds of this species have non‐deep simple morphophysiological dormancy (C_1bB).     

杂交构树UDP-葡萄糖脱氢酶基因编码蛋白的亚细胞定位及其启动子5'端缺失片段的功能分析

为了研究杂交构树UDP-葡萄糖脱氢酶基因（DDBJ,BpUGDH基因登录号为LC457701）启动子不同区域的表达活性,利用5'端缺失及同源重组实验技术,将5个不同长度的BpUGDH启动子5'端缺失片段与GUS基因连接,并通过农杆菌介导法瞬时转化烟草;同时,为了定位BpUGDH基因编码的蛋白在细胞中表达的具体位置,利用GFP报告基因融合目的基因进行蛋白质的亚细胞定位。结果显示：BpUGDH基因启动子-244 bp以内的序列均能介导GUS基因的诱导表达,并且-973、-465、-355、-281和-244 bp之间的区域可能对BpUGDH基因启动子的活性发挥着至关重要的作用。另外,BpUGDH基因编码蛋白的亚细胞定位结果显示：BpUGDH位于叶绿体中。     

两个苜蓿品种营养器官解剖结构特征比较

为了明确具有极强抗虫特性的‘草原4号紫花苜蓿’(Medicago sativa L.‘Caoyuan No.4’) 营养器官的解剖特征,该研究选择具有抗蓟马特性较强的‘草原2号杂花苜蓿’(Medicago varia Martin.‘Caoyuan No.2’)为对照,采用显微镜观察比较两品种的根、茎、叶解剖结构特征,为揭示‘草原4号紫花苜蓿’ 抗蓟马特性提供理论依据。结果显示：(1)‘草原4号紫花苜蓿’根部解剖结构的皮层薄壁细胞厚度、内皮层厚度、形成层厚度、木质部厚度和木射线宽度等5个指标均极显著高于(P＜0.01)‘草原2号杂花苜蓿’,其中木射线宽度(159.37 μm)是‘草原2号杂花苜蓿’的1.82倍。(2)‘草原4号紫花苜蓿’的茎部厚角组织厚度(21.4 μm)极显著高于‘草原2号杂花苜蓿’(P＜0.01),而韧皮部宽度、髓直径却均极显著低于‘草原2号杂花苜蓿’(P＜0.01)。(3)‘草原4号紫花苜蓿’叶片解剖构造的7个指标均极显著高于‘草原2号杂花苜蓿’(P＜0.01),其中栅栏组织层数(2～3层)极明显地高于‘草原2号杂花苜蓿’(1~2层)。研究表明,‘草原4号紫花苜蓿’的组织结构特征具有明显的抗虫特征,且其组织的抗虫特征比‘草原2号杂花苜蓿’更为突出。     

Evolutionary dynamics of tandem repeats in the mitochondrial DNA control region of the minnow Cyprinella spiloptera

Length variation due to tandem repeats is now recognized as a common feature of animal mitochondrial DNA; however, the evolutionary dynamics of repeated sequences are not well understood. Using phylogenetic analysis, predictions of three models of repeat evolution were tested for arrays of 260-bp repeats in the cyprinid fish Cyprinella spiloptera. Variation at different nucleotide positions in individual repeats supported different models of repeat evolution. One set of characters included several nucleotide variants found in all copies from a limited number of individuals, while the other set included an 8- bp deletion found in a limited number of copies in all individuals. The deletion and an associated nucleotide change appear to be the result of a deterministic, rather than stochastic, mutation process. Parallel origins of repeat arrays in different mitochondrial lineages, possibly coupled with a homogenization mechanism, best explain the distribution of nucleotide variation.