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| 2. |
- Beal, Jacob, et al.
(författare)
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Robust estimation of bacterial cell count from optical density
- 2020
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Ingår i: Communications Biology. - : Springer Science and Business Media LLC. - 2399-3642. ; 3:1
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Tidskriftsartikel (refereegranskat)abstract
- Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data.
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| 3. |
- Aad, G, et al.
(författare)
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- 2015
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swepub:Mat__t
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| 4. |
- Du, Fang K., et al.
(författare)
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Direction and extent of organelle DNA introgression between two spruce species in the Qinghai-Tibetan Plateau
- 2011
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Ingår i: New Phytologist. - : Wiley. - 0028-646X .- 1469-8137. ; 192:4, s. 1024-1033
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Tidskriftsartikel (refereegranskat)abstract
- A recent model has shown that, during range expansion of one species in a territory already occupied by a related species, introgression should take place preferentially from the resident species towards the invading species and genome components experiencing low rates of gene flow should introgress more readily than those experiencing high rates of gene flow. Here, we use molecular markers from two organelle genomes with contrasted rates of gene flow to test these predictions by examining genetic exchanges between two morphologically distinct spruce Picea species growing in the Qinghai-Tibetan Plateau. The haplotypes from both mitochondrial (mt) DNA and chloroplast (cp) DNA cluster into two distinct lineages that differentiate allopatric populations of the two species. By contrast, in sympatry, the species share the same haplotypes, suggesting interspecific genetic exchanges. As predicted by the neutral model, all sympatric populations of the expanding species had received their maternally inherited mtDNA from the resident species, whereas for paternally inherited cpDNA introgression is more limited and not strictly unidirectional. Our results underscore cryptic introgressions of organelle DNAs in plants and the importance of considering rates of gene flow and range shifts to predict direction and extent of interspecific genetic exchanges.
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| 5. |
- Hong, Junmei, et al.
(författare)
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Focusing on RISC assembly in mammalian cells.
- 2008
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Ingår i: Biochem Biophys Res Commun. - : Elsevier BV. - 1090-2104 .- 0006-291X. ; 368:3, s. 703-8
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- RISC (RNA-induced silencing complex) is a central protein complex in RNAi, into which a siRNA strand is assembled to become effective in gene silencing. By using an in vitro RNAi reaction based on Drosophila embryo extract, an asymmetric model was recently proposed for RISC assembly of siRNA strands, suggesting that the strand that is more loosely paired at its 5' end is selectively assembled into RISC and results in target gene silencing. However, in the present study, we were unable to establish such a correlation in cell-based RNAi assays, as well as in large-scale RNAi data analyses. This suggests that the thermodynamic stability of siRNA is not a major determinant of gene silencing in mammalian cells. Further studies on fork siRNAs showed that mismatch at the 5' end of the siRNA sense strand decreased RISC assembly of the antisense strand, but surprisingly did not increase RISC assembly of the sense strand. More interestingly, measurements of melting temperature showed that the terminal stability of fork siRNAs correlated with the positions of the mismatches, but not gene silencing efficacy. In summary, our data demonstrate that there is no definite correlation between siRNA stability and gene silencing in mammalian cells, which suggests that instead of thermodynamic stability, other features of the siRNA duplex contribute to RISC assembly in RNAi.
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| 6. |
- Ji, MF, et al.
(författare)
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Mass screening for liver cancer: results from a demonstration screening project in Zhongshan City, China
- 2018
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Ingår i: Scientific reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 8:1, s. 12787-
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Tidskriftsartikel (refereegranskat)abstract
- Current Chinese national guidelines recommend routine screening for liver cancer in patients positive for HBsAg, irrespective of fibrosis status, age, or family history of liver cancer. We aim to evaluate whether the recommended screening strategy could reduce liver-cancer-specific mortality. We conducted a liver cancer mass screening trial in Xiaolan Town, Zhongshan City, China, among residents aged 35–64 years in 2012. All volunteers were offered serological testing for hepatitis B virus surface antigen (HBsAg). We proposed biannual screening using serum alpha-fetoprotein (AFP) and ultrasonography examination for subjects positive for HBsAg. Among 17,966 participants (26.2% of 68,510 eligible residents) who were free of liver cancer at baseline in 2012, we identified 57 incident cases of liver cancer within the first 4 years of follow-up (i.e., 43 among 2,848 HBsAg-positive participants and 14 among 15,118 HBsAg-negative participants), compared with 104 cases identified in non-participants (N = 50,544). A total of 207 participants had the recommended number of ultrasonography examinations (every 6 months) during the screening period. Compared with cases identified from non-participants, the cases arising among participants were more likely to be at early stage and had better survival than those among non-participants. However, we did not observe a reduction in liver cancer-specific mortality rate among participants (relative risk = 1.04, 95% confidence interval = 0.68, 1.58, P = 0.856). Our demonstration screening study does not show a reduction in liver cancer mortality within the first 4 years of follow-up according to current guidance in China, although long-term efficacy remains to be evaluated. Targeted surveillance among high-risk individuals as recommended by international guidelines, along with measures to improve compliance, should be evaluated in the Chinese population.
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| 7. |
- Jiao, Xiang, et al.
(författare)
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PHIP - a novel candidate breast cancer susceptibility locus on 6q14.1
- 2017
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Ingår i: Oncotarget. - : IMPACT JOURNALS LLC. - 1949-2553. ; 8:61, s. 102769-102782
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Tidskriftsartikel (refereegranskat)abstract
- Most non-BRCA1/2 breast cancer families have no identified genetic cause. We used linkage and haplotype analyses in familial and sporadic breast cancer cases to identify a susceptibility locus on chromosome 6q. Two independent genome-wide linkage analysis studies suggested a 3 Mb locus on chromosome 6q and two unrelated Swedish families with a LOD > 2 together seemed to share a haplotype in 6q14.1. We hypothesized that this region harbored a rare high-risk founder allele contributing to breast cancer in these two families. Sequencing of DNA and RNA from the two families did not detect any pathogenic mutations. Finally, 29 SNPs in the region were analyzed in 44,214 cases and 43,532 controls from BCAC, and the original haplotypes in the two families were suggested as low-risk alleles for European and Swedish women specifically. There was also some support for one additional independent moderate-risk allele in Swedish familial samples. The results were consistent with our previous findings in familial breast cancer and supported a breast cancer susceptibility locus at 6q14.1 around the PHIP gene.
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