石灰性土壤上植物根际中Fe,Mn的形态分布及其与植物吸收的关系

研究了石灰性土壤上５种作物品种根际微生态环境中Ｆｅ、Ｍｎ的形态分布．结果表明,交换态Ｆｅ（ＥＸ－Ｆｅ）、碳酸盐结合态Ｆｅ（ＣＡＲＢ－Ｆｅ）、无定形氧化铁（ＡＯ－Ｆｅ）和交换态Ｍｎ（Ｅ－Ｍｎ）、碳酸盐结合态Ｍｎ（ＣＡＲＢ－Ｍｎ）在根际土壤中都呈现明显的累积．各品种根际中的累积量有较大差异．相关分析表明,黄潮土上植株含Ｆｅ量、吸Ｆｅ量与根际土壤ＡＯ－Ｆｅ含量呈显著正相关．根际有效态Ｆｅ累积不仅是根际ｐＨ作用的结果,与根系分泌物对难溶性Ｆｅ活化有关．根际有效态Ｍｎ累积则受到根际土壤Ｅｈ的影响．     

喹诺酮类药物抗乙型肝炎病毒体外实验研究

本文以２．２．１５细胞株为模型,以ＨＢｓＡｇ、ＨＢｅＡｇ、ＨＢＶＤＮＡ、细胞存活率为观察指标,综合评价了喹诺酮类药物吡哌酸（ＰｉｐｅｍｉｄｉｃＡｃｉｄ）、氟哌酸（Ｎｏｒｆｌｏｘａｃｉｎ）、环丙氟哌酸（Ｃｉｐｒｏｆｌｏｓｘａｃｉｎ）、氟嗪酸（Ｏｆｌｏｘａｃｉｎ）体外抗ＨＢＶ效果。结果表明：吡哌酸、氟哌酸、环丙氟哌酸、氟嗪酸对ＨＢｓＡｇ、ＨＢｅＡｇ５０％抑制浓度（ＩＤ＿（５０））分别为１１μｇ／ｍｌ、６４μｇ／ｍｌ、９３μｇ／ｍｌ、１０５μｇ／ｍｌ和１９９μｇ／ｍｌ、１１１μｇ／ｍｌ、２４μｇ／ｍｌ、２１７μｇ／ｍｌ,细胞存活率为５０％时的药物浓度（ＣＤ＿（５０））分别为２１９μｇ／ｍｌ、９０μｇ／ｍｌ、１８１μｇ／ｍｌ、１６９μｇ／ｍｌ,在所选定的用药浓度范围内不同程度抑制培养上清液及细胞内ＨＢＶＤＮＡ及其复制中间体的产生。尤其对超螺旋结构ＤＮＡ（ｓｃＤＮＡ）有不完全抑制作用。     

Detection of proteins and sialoglycoproteins in polyacrylamide gels using eosin Y stain

An eosin Y staining technique that permits detection of various proteins, including membrane sialoglycoproteins, in polyacrylamide gels is described. The sensitivity of the eosin Y staining method is comparable to silver staining. In addition, there is an added advantage of the antigen icily of the stained proteins being retained in a Western blot. Details of the procedure to obtain optimal staining results are described.     

A phenotypic host range alteration determines RD114 virus restriction in feline embryonic cells.

We have characterized the restriction mechanism for RD114 virus replication in embryonic feline cells (FeF). By comparing growth properties of the virus in FeF cells with its behavior in a fetal feline glial cell line (G355) permissive for RD114, we showed that both cell lines were readily infectible by virus grown in permissive cells and that no significant differences in viral integration or viral RNA expression could be detected. However, analysis of viral protein expression revealed differences in viral env gene processing in the two cell types. Envelope precursor pR85 was produced, but the expected processed gp70 product was detectable only in permissive (G355) cells. An envelope product of 85 kDa was packaged into virions produced by FeF cells, while virions produced by G355 cells contained the expected RD114 gp70. While the gp85 env-containing virions were infectious for permissive G355 cells, they were unable to infect FeF cells. The block to infection by the gp85-containing particles in FeF cells could be abrogated by treatment with the glycosylation inhibitor tunicamycin. Our results indicate that restriction of RD114 virus involves a novel mechanism dependent on two factors: altered glycosylation of the envelope to a gp85 form and an altered RD114 receptor in FeF cells.     

Biodegradation of trichloroethylene and toluene by indigenous microbial populations in soil.

The biodegradation of trichloroethylene (TCE) and toluene, incubated separately and in combination, by indigenous microbial populations was measured in three unsaturated soils incubated under aerobic conditions. Sorption and desorption of TCE (0.1 to 10 micrograms ml-1) and toluene (1.0 to 20 micrograms ml-1) were measured in two soils and followed a reversible linear isotherm. At a concentration of 1 micrograms ml-1, TCE was not degraded in the absence of toluene in any of the soils. In combination, both 1 microgram of TCE ml-1 and 20 micrograms of toluene ml-1 were degraded simultaneously after a lag period of approximately 60 to 80 h, and the period of degradation lasted from 70 to 90 h. Usually 60 to 75% of the initial 1 microgram of TCE ml-1 was degraded, whereas 100% of the toluene disappeared. A second addition of 20 micrograms of toluene ml-1 to a flask with residual TCE resulted in another 10 to 20% removal of the chemical. Initial rates of degradation of toluene and TCE were similar at 32, 25, and 18 degrees C; however, the lag period increased with decreasing temperature. There was little difference in degradation of toluene and TCE at soil moisture contents of 16, 25, and 30%, whereas there was no detectable degradation at 5 and 2.5% moisture. The addition of phenol, but not benzoate, stimulated the degradation of TCE in Rindge and Yolo silt loam soils, methanol and ethylene slightly stimulated TCE degradation in Rindge soil, glucose had no effect in either soil, and dissolved organic carbon extracted from soil strongly sorbed TCE but did not affect its rate of biodegradation.     

Post-repolarization block of cardiac sodium channels by saxitoxin.

Phasic block of rat cardiac Na+ current by saxitoxin was assessed using pulse trains and two-pulse voltage clamp protocols, and the results were fit to several kinetic models. For brief depolarizations (5 to 50 ms) the depolarization duration did not affect the rate of development or the amplitude of phasic block for pulse trains. The pulse train data were well described by a recurrence relation based upon the guarded receptor model, and it provided rate constants that accurately predicted first-pulse block as well as recovery time constants in response to two-pulse protocols. However, the amplitudes and rates of phasic block development at rapid rates (> 5 Hz) were less than the model predicted. For two pulse protocols with a short (10 ms) conditioning step to -30 mV, block developed only after repolarization to -150 mV and then recovered as the interpulse interval was increased. This suggested that phasic block under these conditions was caused by binding with increased affinity to a state that exists transiently after repolarization to -150 mV. This "post-repolarization block" was fit to a three-state model consisting of a transient state with high affinity for the toxin, the toxin bound state, and the ultimate resting state of the channel. This model accounted for the biphasic post-repolarization block development and recovery observed in two-pulse protocols, and it more accurately described phasic block in pulse trains.(ABSTRACT TRUNCATED AT 250 WORDS)     

Isolation and identification of a novel tandemly repeated DNA sequence in the centromeric region of human chromosome 8

EcoRI subclones, designated as 50E1 and 50E4, were independently obtained from a cosmid clone previously mapped to the centromeric region of human chromosome 8. Southern blot hybridization analyses suggested that both subclones contain repetitive DNA sequences different from the chromosome 8 specific alphoid DNA. DNA sequence analysis of the 704 bp insert of 50E1 and the 1, 962 bp insert of 50E4 revealed that both inserts contained tandemly repeated units of 220 bp. Fluorescence in situ hybridization studies confirmed these two subclones to be specifically located on the centromeric region of chromosome 8. A 220 bp consensus sequence, derived from nine monomeric repeats, showed no significant homology to alphoid consensus sequences or to other currently known human centromeric DNA sequence. Furthermore, no significant homology was found with any other DNA sequence deposited in the EMBL or GenBank databases, indicating that this chromosome 8 specific repetitive DNA sequence is novel. From slot blot experiments it was estimated that 0.013% of the human genome comprises 1,750 of these monomeric repeats, residing on the centromeric region of chromosome 8 in tandem array(s).     

He—Ne激光对君子兰幼果和胡萝卜根的愈伤组织形成及生长的影响

利用6mv的He—Ne激光器,每天对君子兰幼果、胡萝卜根的外植体辐照5分钟,连续辐照20天,对愈伤组织的形成和生长有一定的促进作用。但同样条件下,辐照10分钟,对君子兰幼果,胡萝卜根的愈伤组织形成和生长都有明显的抑制作用。     

基于差异基因表达谱的Microbacterium sp. XT11降解黄原胶潜能挖掘

为挖掘微杆菌(Microbacterium sp.)XT11在黄原胶降解过程中起关键作用的功能基因,预测黄原胶降解通路,利用转录组测序技术对该菌株在不同碳源培养条件下的转录本进行测序,对差异基因进行功能富集分析。结果表明,菌株XT11以葡萄糖为对照组,以黄原胶为碳源时可获得上调差异基因213个。显著上调的基因主要富集在聚糖降解、淀粉和蔗糖代谢途径、ABC转运、苯丙氨酸代谢、丙酮酸代谢五个KEGG途径。碳水化合物活性酶(Carbohydrate-active enzymes, CAZymes)功能注释表明,位于同一基因簇上的4个CAZymes基因和黄原胶降解直接相关,其余的CAZymes基因具有潜在的黄原胶降解活性。此外,预测到磷酸转移酶系统(phosphotransferase system, PTS)和ABC转运途径(ABC transporters)参与了胞外黄原胶降解中间产物的跨膜转运。挖掘了菌株XT11中黄原胶降解过程中的功能基因,并阐述了菌株XT11的黄原胶降解通路。     

异叶三宝木的二萜成分及抗菌活性研究

为研究异叶三宝木(Trigonostemon heterophyllus)的二萜成分及其抗菌活性,采用硅胶柱层析、凝胶柱层析、高效液相色谱对萃取物进行分离纯化,结合现代波谱技术对所得化合物进行结构鉴定,并通过牛津杯法和2倍稀释法检测化合物对革兰氏阴性菌大肠杆菌(Escherichia coli)以及革兰氏阳性菌肺炎双球菌(Pneumococcus)的生长抑制活性和MIC值。从异叶三宝木中分离得到了6个化合物,包括5个二萜类, 1个木脂素类,分别鉴定为trigonochinene E (1)、neoboutomannin (2)、6,9-O- dedimethyltrigonostemone (3)、stelltian B (4)、3,4-secosonderianol (5)、biondinin A (6)。化合物1、2、3、5对大肠杆菌有抑制作用,MIC值分别为9.375、18.75、18.75、18.75 μg/mL。化合物2、3、4、6为首次从该种植物中分离得到,化合物4为首次从该属植物中分离得到。除化合物4外,其他化合物都有一定的抗菌活性,且化合物1、2、3对大肠杆菌抑制作用强于阳性对照硫酸卡那霉素。