Simple and rapid detection of Salmonella serovar Enteritidis under field conditions by loop-mediated isothermal amplification

AIM

The objective of this study is to develop a serovar-specific loop-mediated isothermal amplification (LAMP) method for sensitive, rapid, and inexpensive detection of Salmonella serovar Enteritidis under field conditions.

METHODS

A set of six specific primers was designed with Salmonella Enteritidis DNA as the target. LAMP conditions were optimized by incubating the target DNA with the Bst DNA polymerase large fragment in a simple water bath. The sensitivity and specificity of LAMP was then compared with those of fluorescent quantitative real-time polymerase chain reaction (FQ-PCR).

RESULTS

The results were as follows. (1) Serovar-specific Salmonella Enteritidis DNA was amplified at 65°C in as early as 20min in a water bath. (2) A colour change visible to the naked eye indicated a positive amplification reaction. (3) The detection limit of the LAMP assay was 4 copies μl(-1) ; thus, the sensitivity and specificity of this assay is similar to those of the FQ-PCR.

CONCLUSIONS

LAMP is a high-throughput detection technique with high sensitivity, specificity, and simplicity; these factors make it suitable for specifically detecting Salmonella Enteritidis under field conditions and in laboratory settings. Thus, LAMP eliminates the need for complicated equipment and technical training in the detection of this specific serovar.

SIGNIFICANCE AND IMPACT OF THE STUDY

This is the first study involving the use of LAMP to detect Salmonella serovar-specific DNA sequences. It is also the first to report an ideal method of distinguishing between Salmonella Enteritidis and other Salmonella under field conditions.

RNAi-mediated germline knockdown of FABP4 increases body weight but does not improve the deranged nutrient metabolism of diet-induced obese mice

Objective:

To investigate the impact of reduced adipocyte fatty acid-binding protein 4 (FABP4) in control of body weight, glucose and lipid homeostasis in diet-induced obese (DIO) mice.

Methods:

We applied RNA interference (RNAi) technology to generate FABP4 germline knockdown mice to investigate their metabolic phenotype.

Results:

RNAi-mediated knockdown reduced FABP4 mRNA expression and protein levels by almost 90% in adipocytes of standard chow-fed mice. In adipocytes of DIO mice, RNAi reduced FABP4 expression and protein levels by 70 and 80%, respectively. There was no increase in adipocyte FABP5 expression in FABP4 knockdown mice. The knockdown of FABP4 significantly increased body weight and fat mass in DIO mice. However, FABP4 knockdown did not affect plasma glucose and lipid homeostasis in DIO mice; nor did it improve their insulin sensitivity.

Conclusion:

Our data indicate that robust knockdown of FABP4 increases body weight and fat mass without improving glucose and lipid homeostasis in DIO mice.

Transition in yield and azimuthal shape modification in dihadron correlations in relativistic heavy ion collisions

Hard-scattered parton probes produced in collisions of large nuclei indicate large partonic energy loss, possibly with collective produced-medium response to the lost energy. We present measurements of π^{0} trigger particles at transverse momenta p{T}{t}=4-12  GeV/c and associated charged hadrons (p{T}{a}=0.5-7  GeV/c) vs relative azimuthal angle Δϕ in Au+Au and p+p collisions at sqrt[s{NN}]=200  GeV. The Au+Au distribution at low p{T}{a}, whose shape has been interpreted as a medium effect, is modified for p{T}{t}<7  GeV/c. At higher p{T}{t}, the data are consistent with unmodified or very weakly modified shapes, even for the lowest measured p{T}{a}, which quantitatively challenges some medium response models. The associated yield of hadrons opposing the trigger particle in Au+Au relative to p+p (I{AA}) is suppressed at high p{T} (I{AA}≈0.35-0.5), but less than for inclusive suppression (R{AA}≈0.2).

Dentigerous cyst: a retrospective clinicopathological analysis of 2082 dentigerous cysts in British Columbia, Canada

The aim of this research is to analyze the prevalence of dentigerous cysts (DCs) in a population-based cohort in British Columbia, Canada, and to report unusual cases associated with DC. The database of the British Columbia Oral Biopsy Service was searched from 1998 to 2007. 2082 histologically confirmed DCs from 2029 patients were retrieved and retrospectively analyzed for incidence, age, gender and ethnicity. The results show that this is a common jaw cyst with male predilection, has a peak incidence in younger adults and is more common in Caucasians. Multiple DCs, representing 2.5% of the cases, are not associated with any syndromes or systemic conditions. 0.5% DCs were associated with other cysts or tumours at the same site or the opposite side of the jaw. The authors report the first series of cases presenting clinically as bilateral DCs, but histologically as an odontogenic tumour or another type of odontogenic cyst. DCs can co-exist with other more serious conditions, such as odontogenic keratocyst or cystic ameloblastoma. This association with more significant conditions indicates the importance of histologically confirming any jaw cyst, even when it presents clinically as a classic DC.

Organochlorine pesticides and PCBs in fish from lakes of the Tibetan Plateau and the implications

High mountains may play significant roles in the global transport of persistent organic pollutants (POPs). This work aims to investigate the levels, patterns and distribution of semi-volatile organochlorine pollutants and to improve the understanding of the long-range atmospheric transport and fate of contaminants on the Tibetan Plateau. A total of 60 fish samples were collected from eight lakes located between 2813 and 4718 m above sea level across the Plateau. Concentrations of polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs) including dichlorodiphenyltrichloroethane and its metabolites (DDTs), hexachlorocyclohexanes (HCHs) and hexachlorobenzene (HCB) were measured in fish muscle. The results showed that concentrations of DDT, HCH and HCB were comparable to or lower than those found in remote mountains of Europe, Canada and US, while PCB concentrations in fish were, on average, about 4-150 times lower on Tibet than at other mountain areas. The transport and fate of contaminants in the Plateau are significantly influenced by the unique climatological and meteorological conditions, particularly by the summer Indian monsoon and winter westerly jet stream.

Historical reconstruction of mercury pollution across the Tibetan Plateau using lake sediments

The Tibetan Plateau is described as the "Roof of the World" averaging over 4000 m above sea level; it is remote, isolated, and presumed to be a pristine region. In order to study the history of atmospheric mercury (Hg) pollution and its spatial variation across the Plateau, lakes were chosen from three areas forming a north to south transect. Sediment cores were taken from three sites in each area and dated using the radionuclides 210Pb and 137Cs. Analysis of the cores yielded the first comprehensive Hg reconstructions for the Plateau, showing clear Hg pollution at all sites. The first indication of Hg pollution is much earlier than the onset of the industrial revolution in Europe, but the most significant pollution increase is from the 1970s, followed by a further marked increase from the 1990s. The mean post-2000 atmospheric pollution Hg accumulation rates for the sampling sites were estimated at between 5.1 and 7.9 microg m(-2) yr(-1). The increase in Hg pollution over the last few decades is synchronous with the recent economic development in Asia (especially China and India), and pollution Hg levels continue to increase. Furthermore, contemporary sediment Hg accumulation rate data are in broad agreement with Hg deposition values derived from global models that attribute pollution to sources mainly within southeast Asia. As most of the sites are exceptionally remote and situated above the atmospheric boundary layer, these results underline the need to understand the local Hg cycle in both regional and global context.

Features of leprosy transmission in pocket villages at low endemic situation in China

To study the characteristics of leprosy transmission at low endemic situation and to analyze the reason why transmission still existed. A retrospective study was carried out on transmission of leprosy in thirteen leprosy high endemic villages in Wenshan district, Yunnan Province, China. A special questionnaire was designed for collecting the data. A total of 47 patients have been registered in 13 villages since 1991. Among them, 25 (53.2%) were leprosy household patients. The proportion of BI positivity was 57.4% (27). The average delay time from disease onset to diagnosis of leprosy was 12 +/- 7.9 months with a range of 1-36 months. The interval between 2 cases being detected in each village was in a range of 0.5 to 5.5 years. Many secondary patients occurred continuously after an 'index case' and they developed leprosy within the delay time of the disease of former patients. The authors here also reviewed some literature on chemoprophylaxis and discussed the importance. Most patients could not be detected at the early stage. It may be necessary of considering the chemoprophylaxis strategy among close contacts of leprosy to stop transmission in leprosy pocket areas.

Bayesian analysis for genetic architecture of dynamic traits

The dissection of the genetic architecture of quantitative traits, including the number and locations of quantitative trait loci (QTL) and their main and epistatic effects, has been an important topic in current QTL mapping. We extend the Bayesian model selection framework for mapping multiple epistatic QTL affecting continuous traits to dynamic traits in experimental crosses. The extension inherits the efficiency of Bayesian model selection and the flexibility of the Legendre polynomial model fitting to the change in genetic and environmental effects with time. We illustrate the proposed method by simultaneously detecting the main and epistatic QTLs for the growth of leaf age in a doubled-haploid population of rice. The behavior and performance of the method are also shown by computer simulation experiments. The results show that our method can more quickly identify interacting QTLs for dynamic traits in the models with many numbers of genetic effects, enhancing our understanding of genetic architecture for dynamic traits. Our proposed method can be treated as a general form of mapping QTL for continuous quantitative traits, being easier to extend to multiple traits and to a single trait with repeat records.

Assessment of polychlorinated biphenyls and polybrominated diphenyl ethers in Tibetan butter

The Tibetan plateau is considered a potential cold trap for persistent organic pollutants (POPs) and plays an important role in the global long-range transport of these compounds. This present work surveyed the concentrations of polychlorinated biphenyl (PCBs) and polybrominated diphenyl ethers (PBDEs) in Tibetan butter samples collected from different prefectures in Tibet autonomous region (TAR). summation operator(25)PCB concentrations ranged from 137 to 2518 pg g(-1) with a mean value 519 pg g(-1), which were far lower than those in the butter from other regions in the world. The highest level was found in butter from Sichuan province, which is located to the east of the Tibetan plateau and the lowest value was in samples from southeast TAR. The average concentration of summation Sigma(12)PBDE was 125 pg g(-1). The sample with highest and lowest summation Sigma(12)PBDE concentration (955 and 18.0 pg g(-1)) was from the south and southeast part of the plateau, respectively. Back trajectory model implied that the sources of these two groups of POPs were by atmospheric deposition in south, whereas the western plateau was mainly influenced by the tropical monsoon from south Asia. Air currents from Sichuan and Gansu province are further responsible for the atmospheric transport of PCBs and PBDEs to the eastern and northern side of the plateau. Local air concentrations of summation Sigma(5)PCBs predicted using air-milk transfer factor were at the lower end of published global levels.

Occurrence of perfluorinated compounds in fish from Qinghai-Tibetan Plateau

Perfluorinated compounds (PFCs) were found in fish muscle collected from high mountain lakes in the Qinghai-Tibetan Plateau, the highest and biggest plateau on Earth. In 96% of the total fifty-nine fish samples were found detectable perfluorooctane sulfonate (PFOS) as prominent PFCs, while only three for perfluorooctanoate (PFOA). The mean PFOS concentrations in fish muscle ranged 0.21ng/g-5.20ng/g based on dry weight, with the maximum in the Palgon Lake (1.30ng/g-7.54ng/g, dw) and the minimum in the Ni-yang River (<0.15ng/g-0.32ng/g, dw) among the seven sampling sites. Long-chain perfluorocarboxylic acids (C10, C11) were also identified in several locations. No significant correlations were observed between PFCs concentrations and sampling altitude or ages (fish). Results of the present work have demonstrated the existence of low level but detectable PFCs pollution in the Qinghai-Tibetan Plateau in China.

Four-locus high-resolution HLA typing in a sample of Mexican Americans

Mexicans are the most common minority population of the United States. From a sample of 553 bone marrow donor registrants of self-described Mexican ancestry, human leukocyte antigen (HLA) loci A, C, B and DRB1 were typed by high resolution sequence based typing (SBT) methods. A total of 47, 34, 76 and 46 distinct alleles at A, C, B and DRB1 respectively were identified, including 3 new alleles. The four-locus haplotype frequency distribution was extremely skewed with only 53.9% of 1106 chromosomes present with more than one estimated copy. Haplotypes of Native American origin were identified. These data form an initial basis for determining the requirements for an adequate donor pool for stem cell transplantation in this population.