Depuration dynamics of oysters (Crassostrea gigas) artificially contaminated by Salmonella enterica serovar Typhimurium     

de Abreu Corrêa A  Albarnaz JD  Moresco V  Poli CR  Teixeira AL  Oliveira Simões CM  Monte Barardi CR 《Marine environmental research》2007,63(5):479-489

The State of Santa Catarina produces the greatest quantity of edible mollusks in Brazil. To guarantee sanitary qualify, mollusk cultures should be monitored for contamination by pathogenic microorganisms. A self-purification or "depuration" system that eliminates Salmonella enterica serovar Typhimurium contamination from oysters has been developed and evaluated. The depuration process occurred within a closed system, in which 1000 L of water was recirculated for 24 h. The water was sterilized with ultraviolet (UV) light, chlorine, or both together. Oysters (Crassostrea gigas) artificially contaminated with S. typhimurium were harvested every 6 h. Samples of oyster tissue were excised and both the presence and numbers of bacteria were determined. Combined UV light and chlorine treatments resulted in total elimination of bacteria within 12 h. Polymerase chain reaction detected bacteria in water exposed to the three treatments. This pioneering study is the first of its kind in Brazil and represents a major contribution to commercial mollusk culture in this country.  相似文献   

调频加网中的随机问题   总被引：2，自引：0，他引：2  

苏永宪 《测绘学院学报》2001,18(3):226-228

调频加网是印刷中最新发展的一项极其重要的技术，它对于提高印刷品质量有着非常重要的作用。随机数产生的速度和质量决定着调频网点的质量，文中主要讨论了调频加网算法中随机数的产生以及随机数发生器的设计，重要讨论了乘同余随机数发生器。  相似文献   

Seismic vulnerability assessment of earthquake-prone mega-city Shillong,India using geophysical mapping and remote sensing     

Saurabh Baruah  Goutam Kashyap Boruah  Sangeeta Sharma  Washim Akram Hoque  Timangshu Chetia  Chandan Dey 《Georisk: Assessment and Management of Risk for Engineered Systems and Geohazards》2020,14(2):112-127

ABSTRACT

The concept of seismic vulnerability is a yard-stick of damage estimation from a probable earthquake considering physical cum social dimension and enables a basis for decision-makers to develop preparedness and mitigation strategies. We aim at vulnerability assessment of the typical urban system of capital city Shillong situated on hilly terrain. High-resolution satellite imagery of Shillong facilitates analysis of building footprints, communication network, and open ground. Different building typologies are identified taking into account the building’s structural configuration assessed through a rapid visual survey of more than 15% of total residential households. Slope map demarcates the landslide-prone area through discrete elevation modelling. A methodology incorporating several parameters e.g. building typology, slope angle, shear wave velocity characteristics, geomorphology, and the number of occupants in correlation with a physical measurement of vulnerability is presented and is applied to estimate the dimension of vulnerability. Additionally, MASW survey indicates lithology up to 30?m deep along with the existence of stiff soil and rocks at different depths whereas resonant frequency is identified to be in the range of 6–8?Hz through H/V ratio. Integrating all, it is observed that more than 60% of Shillong city falls under moderate to higher vulnerability and the rest is less vulnerable.  相似文献   

Multiplex PCR allows simultaneous detection of pathogens in ships' ballast water     

Aridgides LJ  Doblin MA  Berke T  Dobbs FC  Matson DO  Drake LA 《Marine pollution bulletin》2004,48(11-12):1096-1101

There is enormous potential for global transfer of microorganisms, including pathogens, in ships' ballast water. We contend that a major advancement in the study of ballast-water microorganisms in particular, and of aquatic pathogens in general, will be expedited sample analysis, such as provided by the elegant technology of DNA microarrays. In order to use DNA microarrays, however, one must establish the appropriate conditions to bind target sequences in samples to multiple probes on the microarrays. We conducted proof-of-concept experiments to optimize simultaneous detection of multiple microorganisms using polymerase chain reaction (PCR) and Southern hybridization. We chose three target organisms, all potentially found in ballast water: a calicivirus, the bacterium Vibrio cholerae, and the photosynthetic protist Aureococcus anophagefferens. Here, we show simultaneous detection of multiple pathogens is possible, a result supporting the promising future use of microarrays for simultaneous detection of pathogens in ballast water.  相似文献   

Acclimatization and screening of a chloramphenicol-degrading strain     

Xuanwen LU Xueqin TAO Zhi DANG 《中国地球化学学报》2006,25(B08):115-116

Chloramphenicol （CAP） is an antibiotic commonly used in aquaculture as a prophylactic or disinfectant to prevent diseases, or as a chemotherapeutic agent to control diseases. This antibiotic is either spread directly in the aquatic environment or administered through medicated feeds. It may be directly exposed to or enter the environment by leaching from uneaten feeds or from the aquatic animals＇ excrements. The antibiotic also directly enters the environment through pharmaceutical wastewater. Toxicity of CAP to human bone marrow has been linked to fatal aplastic anemia. Antimicrobial residues enter the environment, which may also establish a selective pressure in favour of antimicrobial-resistant bacteria. The residues of antibiotics may pose potential risk to public health or increase the occurrence of antibiotic-resistant bacteria in the aquatic environment. Due to these perceived risk, treatment of CAP in farm animals intended for human consumption has been restricted. However, residue of CAP in the environment is still a concern. There have been some reports on the residual effects of CAP on aquaculture and on microbial resistance to CAP in certain environments. The biotransformation of CAP in aquaculture pond sediments has been reported, which indicated that salinity is one of the many environmental factors that affect the degradation of CAP. However, acclimatization and screening of dominant bacteria for biodegrading CAP have been rarely studied. This paper studied the microbial degradation of CAP. In order to screen the dominant bacteria for degrading, the source of bacteria was sampled from the aquaculture pond sediments of Baiyun Borough, Guangzhou, China. 60 mg/L CAP was used as a sole carbon source to screen CAP-degrading bacteria and the dominant bacteria were acclimated after 2 months.  相似文献   

Analysis of the 16S-23S rDNA intergenic spacers (IGSs) of marine vibrios for species-specific signature DNA sequences   总被引：7，自引：0，他引：7  

Lee SK  Wang HZ  Law SH  Wu RS  Kong RY 《Marine pollution bulletin》2002,44(5):412-420

Vibrios are widespread in the marine environment and a few pathogenic species are known to be commonly associated with outbreaks of diarrheal diseases in humans due to the consumption of raw or improperly cooked seafood. However, there are also many Vibrio species which are potentially pathogenic to vertebrate and invertebrate aquatic animals, and of which little is known. In an attempt to develop rapid PCR detection methods for these latter class of vibrios, we have examined the 16S-23S intergenic spacers (IGSs) of 10 lesser-known Vibrio species and successfully developed species-specific primers for eight of them--Vibrio costicola, V. diazotrophicus, V. fluvialis, V. nigripulchritudo, V. proteolyticus, V. salmonicida, V. splendidus and V. tubiashii. The IGS amplicons were amplified using primers complementary to conserved regions of the 16S and 23S rRNA genes, and cloned into plasmid vectors and sequenced. Analysis of the IGS sequences showed that 37 ribosomal RNA (rrn) operons representing seven different IGS types have been cloned from the 10 vibrios. The three IGS types--IGS(0), IGS(IA) and IGS(Glu)--were the most prevalent forms detected. Multiple alignment of representative sequences of these three IGS types from different Vibrio species revealed several domains of high sequence variability, which were used to design species-specific primers for PCR. The specificity of the primers were evaluated using total DNA prepared from different Vibrio species and bacterial genera. The results showed that the PCR method can be used to reliably detect eight of the 10 Vibrio species in marine waters in this study.  相似文献   

甘肃武山地区地下流体化学与构造应力关系初探     

王非 《内陆地震》1996,10(3):263-268

结合水氧、应力观测资料对甘肃武山地区地下流体化学特征（水化学、气体化学）与构造应力关系进行了定量计算并给出了二者之间的数学关系。  相似文献   

A Method To Detect Viable Helicobacter pylori Bacteria in Groundwater     

Debbie Flanigan  Mark Rodgers 《洁净——土壤、空气、水》2003,31(1):45-48

The inability to detect the presence of viable Helicobacter pylori bacteria in environmental waters has hindered the public health community in assessing the role water may play in the transmission of this pathogen. This work describes a cultural enrichment method coupled with an H. pylori‐specific PCR to identify these bacteria in water. While far from perfected at the present time, this represents an exciting new approach to studying the significance of water as a transmission mechanism for H. pylori. Evidence is presented that indicates culturable H. pylori bacteria were found using this enrichment/PCR method in a local groundwater source.  相似文献   

Identification of Microplankton in South China Sea with Image-Matching Individual PCR     

LI Si  YANG Guanpin  ZHU Baohua  PAN Kehou 《中国海洋大学学报(英文版)》2019,(1):219-226

In this study, marine microplankton were identified by combining standard light microscopy with Sanger 18S rRNA gene sequencing. The image-matching individual PCR technique was applied to identify the image collectable unicellular microplankton to genera. Instead of pure strain culture and morphological identification, microplankton individual cells were isolated and fixed with glutaraldehyde, frozen and stored for months. Finally, they were imaged under a microscope and molecularly identified via phylogenetic analysis of their 18S ribosomal RNA gene(18S rDNA). Microplankton cells were collected at 30 locations in South China Sea, and were assigned to 21 known and 4 unidentified genera(2 uncultured fungi and 2 uncultured stramenopiles) with phylogenetic analysis in parallel to the morphological identification.  相似文献   

链状亚历山大藻组蛋白H3基因克隆与生长过程中的表达分析     

刘昊昕  Sadaf Riaz  刘源  Anam Khurshid  张巍  隋正红 《海洋科学》2019,43(11):19-27

链状亚历山大藻(Alexandrium catenella)是一种典型的产毒赤潮甲藻。甲藻曾被认为没有组蛋白,但近年来在多种甲藻中检测到全部四个核心组蛋白的活跃转录,而目前对甲藻中组蛋白表达模式与具体功能还缺乏深入的研究。本文报道了链状亚历山大藻组蛋白H3变体之一H3.c的全长ORF序列的克隆和分析;分析了链状亚历山大藻生长过程中组蛋白H3在基因和蛋白水平的表达。目前研究发现的链状亚历山大藻H3变体共三个,其中H3.b在N末端序列与其他物种差异最大,为链状亚历山大藻特有的H3变体。对数生长期的组蛋白H3在基因与蛋白水平上均活跃表达,但表达量并不会随着爆发性增长而显著变化,其中H3.b的基因表达在对数末期呈现上调;培养至衰亡期,各H3变体表达均下调,尤其在蛋白水平上呈现明显衰减。结合前期研究,本文认为链状亚历山大藻三个H3均为复制非依赖型(RI)变体,一些变体可响应伴随藻不断生长而逐渐增强的细胞密度等复杂胁迫,推测其参与某些表观遗传修饰,调控生长进程;而衰亡期基于H3的表观遗传调控受到抑制。  相似文献