Detection of protease-resistant cervid prion protein in water from a CWD-endemic area

Chronic wasting disease (CWD) is the only known transmissible spongiform encephalopathy affecting free-ranging wildlife. Although the exact mode of natural transmission remains unknown, substantial evidence suggests that prions can persist in the environment, implicating components thereof as potential prion reservoirs and transmission vehicles.^1–4 CWD-positive animals may contribute to environmental prion load via decomposing carcasses and biological materials including saliva, blood, urine and feces.^5–7 Sensitivity limitations of conventional assays hamper evaluation of environmental prion loads in soil and water. Here we show the ability of serial protein misfolding cyclic amplification (sPMCA) to amplify a 1.3 × 10⁻⁷ dilution of CWD-infected brain homogenate spiked into water samples, equivalent to approximately 5 × 10⁷ protease resistant cervid prion protein (PrP^CWD) monomers. We also detected PrP^CWD in one of two environmental water samples from a CWD endemic area collected at a time of increased water runoff from melting winter snow pack, as well as in water samples obtained concurrently from the flocculation stage of water processing by the municipal water treatment facility. Bioassays indicated that the PrP^CWD detected was below infectious levels. These data demonstrate detection of very low levels of PrP^CWD in the environment by sPMCA and suggest persistence and accumulation of prions in the environment that may promote CWD transmission.Key words: prions, chronic wasting disease, water, environment, serial protein misfolding cyclic amplification     

Freshwater crayfish invasions in South Africa: past,present and potential future

Freshwater crayfish invasions have been studied around the world, but less so in Africa, a continent devoid of native freshwater crayfish. The present study reviews historical and current information on alien freshwater crayfish species introduced into South Africa and aims to indicate which areas are at risk from invasion. As is the case elsewhere, South Africans have shown a keen interest in both farming and keeping freshwater crayfish as pets, which has resulted in Cherax cainii, Cherax destructor, Cherax quadricarinatus and Procambarus clarkii being introduced to the country. There is evidence of successful establishment in the wild for C. quadricarinatus and P. clarkii in different parts of the country. Species distribution models suggest that the eastern part of the country and parts of the Eastern and Western Cape are at higher risk of invasion. At present, illegal translocations represent the most likely pathway of crayfish spread in South Africa. A continued risk of invasion by freshwater crayfish species in South Africa is highlighted, which reinforces the need for more research, as well as for strong mitigation measures, such as stronger policing of existing regulations, management or eradication where feasible and public education.     

电子供体及受体对棕色固氮菌抗氨阻遏能力的影响

电子供体连二亚硫酸钠,甲基紫精及电子受体亚甲蓝均能强烈的抑制棕色固氮菌表达固氮活性,并引起该菌的抗氨阻遏能力减弱,适当提高氧压,能提高菌体的固氮活性近15％,但过高的氧分压反而抑制菌体的固氮活性,此外,提高氢分压能降低棕色固氮菌菌体内的还原电位,从而达到提高菌体抗氨阻遏能力的效果。     

Genomic DNA released by dying cells induces the maturation of APCs

Mature APCs play a key role in the induction of Ag-specific immunity. This work examines whether genomic DNA released by dying cells provides a stimulus for APC maturation. Double-stranded but not single-stranded genomic DNA triggered APC to up-regulate expression of MHC class I/II and various costimulatory molecules. Functionally, dsDNA enhanced APC function in vitro and improved primary cellular and humoral immune responses in vivo. These effects were dependent on the length and concentration of the dsDNA but were independent of nucleotide sequence. The maturation of APC induced by dsDNA may promote host survival by improving immune surveillance at sites of tissue injury/infection.     

The effect of nitric oxide combined with fluoroquinolones against Salmonella enterica serovar Typhimurium in vitro

Two regulons, soxRS and marRAB, are associated with resistance to quinolones or multiple antibiotic in Salmonella enterica serovar Typhimurium. These regulons are activated by nitric oxide and redox-cycling drugs, such as paraquat and cause on activation of the acrAB-encoded efflux pump. In this study, we investigated the effect of nitric oxide (NO) alone and in combination with ofloxacin, ciprofloxacin, and pefloxacin against S. typhimurium clinical isolates and mutant strains in vitro. We did not observe synergistic effect against clinical isolates and SH5014 (parent strain of acr mutant), while we found synergistic effect against PP120 (soxRS mutant) and SH7616 (an acr mutant) S. typhimurium for all quinolones. Our results suggest that the efficiencies of some antibiotics, including ofloxacin, ciprofloxacin, and pefloxacin are decreased via activation of soxRS and marRAB regulons by NO in S. enterica serovar Typhimurium. Further studies are warranted to establish the interaction of NO with the genes of Salmonella and, with multiple antibiotic resistance.     

Isolation and characterization of microsatellites in Neogobius kessleri (Perciformes,Gobiidae) and cross‐species amplification within the family Gobiidae

Fourteen polymorphic microsatellites were isolated from Neogobius kessleri, a benthic fish of Ponto‐Caspian origin which has been recently introduced into the Middle and Upper Danube River. Number of alleles and heterozygosity per locus in a sample of 32 fish individuals ranged from two to four and from 0.13 to 0.75, respectively. These primers will be useful in determining the population structure of N. kessleri. In addition, successful cross‐amplification was obtained for four related species, N. melanostomus, N. fluviatilis, N. gymnotrachelus and Proterorhinus marmoratus. These microsatellite loci may be useful for the evaluation of the origin of non‐native goby populations.     

A mRNA landscape of bovine embryos after standard and MAPK-inhibited culture conditions: a comparative analysis

Background

Genes and signalling pathways involved in pluripotency have been studied extensively in mouse and human pre-implantation embryos and embryonic stem (ES) cells. The unsuccessful attempts to generate ES cell lines from other species including cattle suggests that other genes and pathways are involved in maintaining pluripotency in these species. To investigate which genes are involved in bovine pluripotency, expression profiles were generated from morula, blastocyst, trophectoderm and inner cell mass (ICM) samples using microarray analysis. As MAPK inhibition can increase the NANOG/GATA6 ratio in the inner cell mass, additionally blastocysts were cultured in the presence of a MAPK inhibitor and changes in gene expression in the inner cell mass were analysed.

Results

Between morula and blastocyst 3,774 genes were differentially expressed and the largest differences were found in blastocyst up-regulated genes. Gene ontology (GO) analysis shows lipid metabolic process as the term most enriched with genes expressed at higher levels in blastocysts. Genes with higher expression levels in morulae were enriched in the RNA processing GO term. Of the 497 differentially expressed genes comparing ICM and TE, the expression of NANOG, SOX2 and POU5F1 was increased in the ICM confirming their evolutionary preserved role in pluripotency. Several genes implicated to be involved in differentiation or fate determination were also expressed at higher levels in the ICM. Genes expressed at higher levels in the ICM were enriched in the RNA splicing and regulation of gene expression GO term. Although NANOG expression was elevated upon MAPK inhibition, SOX2 and POU5F1 expression showed little increase. Expression of other genes in the MAPK pathway including DUSP4 and SPRY4, or influenced by MAPK inhibition such as IFNT, was down-regulated.

Conclusion

The data obtained from the microarray studies provide further insight in gene expression during bovine embryonic development. They show an expression profile in pluripotent cells that indicates a pluripotent, epiblast-like state. The inability to culture ICM cells as stem cells in the presence of an inhibitor of MAPK activity together with the reported data indicates that MAPK inhibition alone is not sufficient to maintain a pluripotent character in bovine cells.

Electronic supplementary material

The online version of this article (doi:10.1186/s12864-015-1448-x) contains supplementary material, which is available to authorized users.     

Evaluation of four colourimetric susceptibility tests for the rapid detection of multidrug-resistant Mycobacterium tuberculosis isolates

The purpose of this study is to evaluate four rapid colourimetric methods, including the resazurin microtitre assay (REMA), malachite green decolourisation assay (MGDA), microplate nitrate reductase assay (MNRA) and crystal violet decolourisation assay (CVDA), for the rapid detection of multidrug-resistant (MDR) tuberculosis. Fifty Mycobacterium tuberculosis isolates were used in this study. Eighteen isolates were MDR, two isolates were only resistant to isoniazid (INH) and the remaining isolates were susceptible to both INH and rifampicin (RIF). INH and RIF were tested in 0.25 µg/mL and 0.5 µg/mL, respectively. The agar proportion method was used as a reference method. MNRA and REMA were performed with some modifications. MGDA and CVDA were performed as defined in the literature. The agreements of the MNRA for INH and RIF were 96% and 94%, respectively, while the agreement of the other assays for INH and RIF were 98%. In this study, while the specificities of the REMA, MGDA and CVDA were 100%, the specificity of the MNRA was lower than the others (93.3% for INH and 90.9% for RIF). In addition, while the sensitivity of the MNRA was 100%, the sensitivities of the others were lower than that of the MNRA (from 94.1-95%). The results were reported on the seventh-10th day of the incubation. All methods are reliable, easy to perform, inexpensive and easy to evaluate and do not require special equipment.     

基于红外相机技术分析鼬獾的活动节律

鼬獾(Melogale moschata)是食肉目鼬科鼬獾属动物,在我国分布广泛、种群数量丰富,但有关鼬獾的生态研究报导比较少.为掌握鼬獾的活动节律及其影响因素,2017年2月至2019年2月,利用红外相机技术对江西省桃红岭梅花鹿国家级自然保护区、九岭山国家级自然保护区和齐云山国家级自然保护区的鼬獾进行了监测,每个保护...