黄淮海平原封丘试区水体理化性状的多元分析

在封丘试区内两个最具代表性水体(曹岗湖,潘店芦苇荡)水质调查的基础上,对主要水质指标及其集合进行方差分析和聚类分析,结果表明:封丘试区水体具有典型的北方水体特征,其水质的变化主要受季节影响,水体间无甚大差别。各水体pH值偏高(年平均值为8.0—9.0),属弱碱性;硬度较大(17.54—20.63德国度),均属硬水且有逐年上升趋势;离子总量较大(860—1448mg/L);碱度(4.57—5.20me/L)和主要营养物含量(总氮1.31—2.08mg/L,总磷0.100—0.135mg/L)较高,属富营养型水体。文中指出:该试区水体水质状况较好,渔业开发潜力较大,但磷是水体生物生产力的主要限制性营养物。     

Marsdenosides A-H, polyoxypregnane glycosides from Marsdenia tenacissima

Eight polyoxypregnane glycosides, marsdenosides A-H, were isolated from the CHCl(3)-soluble fraction of the ethanolic extract of the stem of Marsdenia tenacissima, along with six known glycosides and two known polyoxypregnane aglycones. Three polyoxypregnanes, 12beta-O-2-methylbutyryl-tenacigenin A, 11alpha,12beta-di-O-acetyltenacigenin B, and 11alpha-O-tigloyltenacigenin B were also obtained. Their structures were established on the basis of spectroscopic analysis and chemical evidence.     

Targeting early proximal-rod component substrate FlgB to FlhB for flagellar-type III secretion in Salmonella

The Salmonella flagellar secretion apparatus is a member of the type III secretion (T3S) family of export systems in bacteria. After completion of the flagellar motor structure, the hook-basal body (HBB), the flagellar T3S system undergoes a switch from early to late substrate secretion, which results in the expression and assembly of the external, filament propeller-like structure. In order to characterize early substrate secretion-signals in the flagellar T3S system, the FlgB, and FlgC components of the flagellar rod, which acts as the drive-shaft within the HBB, were subject to deletion mutagenesis to identify regions of these proteins that were important for secretion. The β-lactamase protein lacking its Sec-dependent secretion signal (Bla) was fused to the C-terminus of FlgB and FlgC and used as a reporter to select for and quantify the secretion of FlgB and FlgC into the periplasm. Secretion of Bla into the periplasm confers resistance to ampicillin. In-frame deletions of amino acids 9 through 18 and amino acids 39 through 58 of FlgB decreased FlgB secretion levels while deleting amino acid 6 through 14 diminished FlgC secretion levels. Further PCR-directed mutagenesis indicated that amino acid F45 of FlgB was critical for secretion. Single amino acid mutagenesis revealed that all amino acid substitutions at F45 of FlgB position impaired rod assembly, which was due to a defect of FlgB secretion. An equivalent F49 position in FlgC was essential for assembly but not for secretion. This study also revealed that a hydrophobic patch in the cleaved C-terminal domain of FlhB is critical for recognition of FlgB at F45.     

Performance Evaluation of the Maxwell 16 System for Extraction of Influenza Virus RNA from Diverse Samples

This study evaluated the performance of the Maxwell 16 System (Promega) for extraction of influenza virus (flu-v) RNA from diverse samples compared to a classical manual method (QIAamp Kit, QIAGEN). Following extraction by the two methods, all samples were analyzed by Real-time RT-PCR. Results revealed that the use of the standard Maxwell 16 protocol (Maxwell 16-S) resulted in good linearity and precision across a wide concentration range and higher sensitivity of detection from flu-v stock suspensions than the manual method. Compared with the latter method, Maxwell 16-S extracted RNA more efficiently (higher RNA yield and/or fewer PCR inhibitors) from throat swabs and bronchoalveolar lavage fluids, while both methods performed comparably on fecal samples from human and poultry in terms of overall threshold cycle values and detection rates although the Maxwell 16-S co-purified more inhibitors from fecal samples. The capacity of this system to remove inhibitors from fecal matrix was improved by using a modified Maxwell 16 protocol with a reduced sample input, which eliminated all false-negatives produced by the Maxwell 16-S. These findings suggest that the Maxwell 16 System is suitable for RNA extraction from multiple-source samples for diagnosis of influenza and viral load determination and that a proper reduction in starting sample volume may improve the detection of flu-v from complex matrices such as feces. Additionally, this system allows flexible sample throughput and labor-saving sample processing with little or no risk of cross-contamination.     

Clinical and Imaging Characteristics of Cerebral Schistosomiasis

In recent years, there has been a trend for increased incidence of cerebral schistosomiasis. It is often misdiagnosed because of the diversity of clinical symptoms. We wished to explore clinical characteristics and imaging findings in cerebral schistosomiasis. We retrospectively analyzed clinical data, laboratory tests, CT, and MRI results in 11 patients with cerebral schistosomiasis. All patients had chronic cerebral schistosomiasis (five with epilepsy type, five with brain tumor type, and one patient with stroke type). All patients with brain tumor type were misdiagnosed as having gliomas. There were typical findings on CT and MRI. In conclusion, clinical manifestations of cerebral schistosomiasis are variable, and the rate of misdiagnosis is high. For more precise diagnosis, a combination of laboratory and imaging data is required.     

新疆阜康盐碱地可培养兼性嗜碱放线菌多样性及其酶活筛选

摘要:【目的】分析新疆阜康盐碱地环境可培养兼性嗜碱放线菌物种多样性及其产酶潜力。【方法】从阜康盐碱地环境共采集10份土样,采用纯培养物的16S rRNA基因序列同源性分析盐碱地兼性嗜碱放线菌物种多样性。对分离菌株进行淀粉酶、蛋白酶、纤维素酶和木聚糖酶酶活初筛。【结果】从10份土样中共分离到116株兼性嗜碱放线菌和4株耐碱放线菌,16S rRNA基因序列分析表明它们分布在放线菌门放线菌纲的8个目13个科22个属,其中53.3%的菌株为非链霉菌属和拟诺卡氏菌属的菌株。酶活初筛结果:淀粉酶、蛋 白酶、木聚糖酶和纤维素酶的阳性率分别为35.8%、37.5%、28.3%、17.5%。【结论】阜康盐碱地生境蕴藏丰富的兼性嗜碱放线菌资源。兼性嗜碱放线菌是获得高活性酶的资源。本研究有助于认识高碱环境兼性嗜碱放线菌的多样性,为其资源的开发利用提供依据。     

Toxoplasma gondii isolates: multilocus RFLP-PCR genotyping from human patients in Sao Paulo State, Brazil identified distinct genotypes

This study investigated the genetic characteristics of Toxoplasma gondii samples collected from 62 patients with toxoplasmosis in Sao Paulo State, Brazil. DNA samples were isolated from blood, cerebrospinal fluid and amniotic fluids of 25 patients with cerebral toxoplasmosis and AIDS, two patients with acute toxoplasmosis, 12 patients with ocular toxoplasmosis, six newborns with congenital toxoplasmosis and 17 pregnant women with acute infection. Diagnosis of toxoplasmosis was based in clinical, radiological and laboratory features. Genotyping was performed using multilocus PCR–RFLP genetic markers including SAG1, SAG2, 5′- and 3′-SAG2, alt.SAG2, SAG3, BTUB, GRA6, C22-8, c29-2, L358, PK1 and Apico. Among the 62 clinical samples, 20 (32%) were successfully genotyped at eight or more genetic loci and were grouped to three distinct genotypes. Eighteen samples belonged to ToxoDB Genotype #65 and the other two samples were identified as ToxoDB Genotypes #6 and #71, respectively (http://toxodb.org/toxo/). Patients presenting Genotypes #6 and #71 had severe and atypical cerebral toxoplasmosis, characterized by diffuse encephalitis without extensive brain lesions. These results indicate that T. gondii Genotype #65 may have a high frequency in causing human toxoplasmosis in Sao Paulo State, Brazil. This unusual finding highlights the need to investigate the possible association of parasite genotypes with human toxoplasmosis.     

Divergence between general public's risk perception and environmental risk assessment: A case study of p-xylene projects in China

The growing public opposition to p-xylene (PX) project proposals in China requires understanding the divergence between the general public's risk perception and environmental risk assessment (ERA) results and its implications on its decision-making. In a case study in Fujian Province of China, a questionnaire was designed to investigate the public perception of risks of a proposed PX project, interviews were further conducted in Zhangzhou City and Xiamen City, and the survey results were compared with the ERA results of the proposed PX project. Results indicate that the environmental risk is acceptable according to current technical ERA guidelines and standards, while the public acceptance of the PX project is very low. The underlying factors causing the difference between the general public's risk perception and ERA results were identified from the ERA technical perspective. A better understanding of the risk perception divergence from different disciplinary perspectives is helpful for the public acceptance of these kinds of projects, which are on high demand in China. This study not only highlights the necessity to improve the risk communication but also provides insights on future research of ERA for this kind of large-scale project proposal.