Effect of mutations in Shigella flexneri chromosomal and plasmid-encoded lipopolysaccharide genes on invasion and serum resistance

This study shows that both length and distribution of lipopolysaccharide (LPS) are important for Shigella flexneri invasion and virulence. Mutants were generated in the chromosomal LPS synthesis genes rfa , rfb , and rol , and in a plasmid-encoded O-antigen chain-length regulator, cld _pHS-2. LPS analysis showed that mutations in rfb genes and in a candidate rfaL gene either eliminated the entire O-antigen side chains or produced chains of greatly reduced length. Mutation in a previously unidentified gene, rfaX , affected the LPS core region and resulted in reduced amounts of O-antigen. Mutants defective in cld _pHS-2 or rol had different distributions of O-antigen chain lengths. The results of tissue-culture cell invasion and plaque assays, the Serény test, and serum-sensitivity assay suggested roles for the different LPS synthesis genes in bacterial survival and virulence; rfaL, rfaX and rfb loci are required for serum resistance and intercellular spread, but not for invasion; cld _pHS-2 is required for resistance to serum killing and for full inflammation in the Serény test, but not for invasion or intercellular spread, while rol is required for normal invasiveness and plaque formation, but not for serum resistance. Thus, O-antigen synthesis and chain-length regulation genes encoded on both the chromosome and the small plasmid pHS-2 play important roles in S. flexneri invasion and virulence.     

蚊幼对狼蛛的营养作用研究

研究蚊子幼虫（子孓）以拟水狼蛛（Ｐｉｒａｔａｓｕｂｐｉｒａｔｉｃｕｓ）的营养,繁殖作用,结果表明狼蛛对蚊幼的捕食符合ＨｏｌｌｉｎｇⅡ型功能反应,喂以蚊幼和不喂蚊幼处理狼蛛的体重增长率和生殖有极显著差异,在相同蚊幼密度下,狼蛛初始体重越小,增长率越大,经计算狼蛛每增重１ｍｇ,需消耗１０．５８ｍｇ蚊幼,这基本符合生态系统营养级能量流动的１／１０法则,狼蛛体重大小对褐飞虱的捕食量有明显差异,体重大的个体     

谷胱甘肽硫转移酶基因表达的调控

催化内源性或外源性亲电子化合物与谷胱甘肽(GSH)结合的谷胱甘肽硫转移酶(GST)超基因家族是一族解毒功能蛋白.其基因的表达通过不同的机制受多种物质的调控.根据最近文献资料,对调控谷胱甘肽硫转移酶基因表达的基因结构、调控机制及氧化应激对谷胱甘肽硫转移酶基因表达的调控作用等作一简要综述.     

薏苡胚乳传递细胞的超微结构

传粉后１０ ｄ,薏苡（Ｃｏｉｘ ｌａｃｒｙｍ ａ－ｊｏｂｉＬ．）颖果基部胚乳最外层传递细胞具长而多的壁内突,第二层细胞的壁内突较第一层的短而少,均具瓣裂的细胞核、丰富的线粒体、粗糙内质网、核糖体、产生小泡的高尔基体及与壁内突质膜相连的、含深色物质的囊泡。线粒体分布于壁内突附近或其间。授粉后２５ ｄ,第一、二层细胞壁内突发达,几乎充满了细胞,但细胞器可见。第四层传递细胞具树枝状及网状的壁内突,大量线粒体、具质体膜的淀粉粒、脂体存在壁内突附近或壁内突的间隙内。高尔基体常见,仅见很少的片段内质网。第五层传递细胞具短的壁内突、较大的淀粉粒及许多小蛋白质体。两个时期的第一、二层细胞内均未观察到胞间连丝。授粉后２５ ｄ,第四层及以上的传递细胞的细胞壁和呈网状的壁内突均含有胞间连丝。还讨论了各种细胞器的作用及各层传递细胞的功能     

玉米根ABA结合蛋白的亚细胞定位及动力学性质

以玉米（Ｚｅａ ｍａｙｓＬ．）根或胚芽鞘为材料,经匀浆、分级离心得到胞质部分和膜部分（微粒体）,进一步用６．２％ （Ｗ／Ｗ ） Ｄｅｘｔｒａｎ Ｔ５００ 和ＰＥＧ ３３５０ 两相系统制备质膜,用１％ 和８％ （Ｗ ／Ｗ） Ｄｅｘｔｒａｎ Ｔ７０ 梯度离心制备液泡膜． 电镜鉴定及多种标志酶检测表明,制备获得了高纯度正向型质膜和富含液泡膜的组分,其它内膜的污染很少． 用微量放射配体结合（ＭＲＬＢ）实验证明,玉米根微粒体的ＡＢＡ专一性结合位点主要分布在液泡膜和质膜上,这两种膜组分与ＡＢＡ 的特异结合活性分别为２４８５．４ ｆｍ ｏｌ／ｍ ｇ ｐｒｏｔｅｉｎ 和１２５７．３ ｆｍ ｏｌ／ｍ ｇ ｐｒｏ－ｔｅｉｎ,玉米根段胞质部分结合活性最低（差一个数量级）．质膜上ＡＢＡ－ＢＰ与ＡＢＡ 的结合平衡解离常数（ＫＤ）为１．５７ ｎｍ ｏｌ／Ｌ．     

四川地区幼儿和学龄前儿童的鼻部测量

本文报告１１１６例四川地区幼儿和学龄前儿童（２－７岁）鼻部９项指标的测量均数,性差及年龄发育特点。性差：仅鼻凹鼻底距４－６．５岁等少数指标部分年龄段男女性间出现显著性划异（男＞女）。此外各项指标的绝大多数年龄段男女性间无显著性差异。年龄发育：９项测量指标中７项的生长曲线随年产长而上升,数值随年龄增大,并有１－２个发育高峰;提示鼻部发育具有阶段性;２项指标的曲线随年龄增长变化较小。４项指标男女性的曲     

河南新乡地区儿童头面部测量

本文对河南省新乡地区汉族儿童（４－１３岁）头面部进行了测量,比较和分析了儿童体质发育与年龄增长的关系,据儿童头面部各指数数值大小分型,确定该地区汉族儿童面部的形态为：圆头型、高头型、狭头型、狭面型、狭鼻型。     

氧化应激与cfos和cjun转录和AP－1激活

激活剂蛋白-1(activator protein-1,AP-1)是近年来受到关注的与氧化应激基因表达调控有关的转录因子.文章就氧化应激与cfos和cjun基因表达,AP-1的激活,AP-1对氧化应激反应的调控,AP-1与亲电子反应元件等有关内容作了简要的综述．     

Studies of adult amphibian heart cells in Vitro: DNA synthesis and mitosis

The ventricle of the adult newt heart was excised and cut into several pieces of approximately 0.5 – 1.0 mm. These heart pieces were then cultured for 60 days at 25 °C in a modified Leibovitz medium (L-15). Approximately 37% of the explants were attached to the substrate and more than 33% of the attached explants and approximately 15% of the unattached explants established pulsation rates which ranged 3–67 beats/min. The explants were labeled with 1 μCi/ml of ³H-thymidine for 24 hr at 7, 15, 21, 30, 45 and 60 days of culture initiation, and processed for electron microscopic autoradiography. The examination of the autoradiograms revealed that as the culture continued, the cardiac muscle cells altered their morphology, resembling embryonic cardiac muscle cells. These altered muscle cells were termed dedifferentiated cardiac muscle cells. The number of these dedifferentiated cells increased over the period of culture, showing 10.3–94% dedifferentiated cells after 7–60 days of culture respectively. DNA synthesis and mitosis were observed in the dedifferentiated cardiac muscle cells, apart from the non-muscle cells. The quantitation of the autoradiograms revealed that the number of labeled nuclei in the cardiac muscle cells gradually increased over the period of culture, and a maximum number of labeled cardiac muscle cells (30%) was observed in the third week. The peak was followed by a decline in the eighth week which exhibited 1.5 % labeled cardiac muscle cells. The trend of mitosis was similar to that of DNA synthesis. The maximum number of mitotic figures (9%) was observed in the third week of culture, which was followed by a decline and finally absent in the eighth week. The cardiac non-muscle cells, mostly fibroblasts and endothelial cells, also showed incorporation of ³H-thymidine in their nuclei. The number of labeled non-muscle cells nuclei and the mitotic index were highest (61 and 15% respectively) in the first week of culture, but then they decreased gradually over the eight-week period in culture. This study provides evidence for the first time that the adult amphibian cardiac myocytes can undergo DNA synthesis and mitosis when explanted and cultured. The significance of this cell replication is discussed.     

Sensory innervation of the gastro-intestinal junction: new electrophysiological, histological and histochemical data]

The sensory innervation of the small intestine was studied in the cat with electrophysiological, histological and histochemical techniques. Thanks to the histochemical technique (peroxydase method) the exact number and proportion of splanchnic and vagal fibres was determined : the latter being about 9 times more numerous than the former. On the other hand the exact position of the corresponding cells was defined in the nodose and spinal ganglia by means of the previous technique and the microelectrophysiological method (recording of single units into the ganglia with extracellular glass microelectrodes). The splanchnic neurones were found in the T9, T10 and T11 ganglia whereas the vagal ones were chiefly located in the lower half of the nodose ganglia. The histological studies using electronic microscope showed many non-medullated endings, which were often found beneath the epithelium and in the lamina propria of the villi close to the blood vessels. This result is certainly the proof that numerous receptors (mechanoreceptors, chemoreceptors and even thermoreceptors do exist in the small intestine.