| 1. |
- 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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| 2. |
- Outomuro, David, et al.
(författare)
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Does allometry of a sexually selected ornamental trait vary with sexual selection intensity? : A multi-species test in damselflies
- 2014
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Ingår i: Ecological Entomology. - : Wiley. - 0307-6946 .- 1365-2311. ; 39:3, s. 399-403
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Tidskriftsartikel (refereegranskat)abstract
- Ornaments may show hyperallometry in certain taxa, i.e. large individuals have proportionally larger ornaments than small ones. One hypothesis suggests that higher sexual selection intensity leads to steeper hyperallometric patterns. This study tested whether an ornamental trait subject to both intra- and intersexual selection showed steeper allometric slopes than when subject solely to intrasexual selection. The study employed the sexually selected male wing pigmentation of 14 calopterygid species (damselflies) that differ in sexual selection intensity (intrasexual selection versus intra- and intersexual selection). Hyperallometry was not a uniform pattern in the study species. Furthermore, the allometric slopes did not differ between sexual selection intensities. The allometry of ornamental traits is therefore highly variable even among related species. Other selection pressures-probably species-specific and at a local scale-acting on wing pigmentation might explain the diversity of allometric patterns.
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| 3. |
- Saito, Rieko, 1980-, et al.
(författare)
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Pedagogical Methods in Web-Based Language Teaching
- 2014
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Ingår i: Proceedings of the 22nd International Conference on Computers in Education. - Japan : ICCE 2014 Organizing Committee. ; , s. 768-772
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Konferensbidrag (refereegranskat)abstract
- This paper presents a research project that is being conducted at Dalarna University in Sweden. The aim is to study the following: 1) The quality of online language education compared with that of campus education, and 2) Advantages and disadvantages of online language education and how the disadvantages might be overcome. The project consists of two parts: pedagogical methods in online language education from the teachers’ point of view and from the students’ point of view. The first part was conducted in 2012 and various characteristics (benefits and difficulties) of online language education were identified. Flexibility and wider opportunities were general benefits, while lack of physical co-presence, difficulty in having lively debates/discussions, and high dropout rates were among the problems. The second part of the project (being conducted in 2014) aims to investigate how students experience online language learning. The goal is to explore alignments and misalignments between teachers’ perspectives and students’ perspectives, and to develop methods to enhance the quality of online education.
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| 4. |
- Sanchez Guillen, Rosa, et al.
(författare)
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Rapid evolution of prezygotic barriers in non-territorial damselflies
- 2014
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Ingår i: Biological Journal of the Linnean Society. - : Oxford University Press (OUP). - 0024-4066. ; 113:2, s. 485-496
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Tidskriftsartikel (refereegranskat)abstract
- A central question in evolutionary biology concerns the accumulation of reproductive barriers during speciation. However, separating the reproductive barriers that have led to speciation from those that have secondarily accumulated (i.e. after initial divergence) is a widely recognized problem. Ideal candidate species for overcoming this problem are young species, where time for additional barriers to accrue has been limited. In the present study, we add to previous studies investigating the strength of reproductive barriers between the parapatric damselflies Ischnura elegans and Ischnura graellsii by quantifying seven prezygotic barriers between the allopatric pairs of I.elegans and Ischnura genei, as well as I.graellsii and I.genei. Specifically, we measured four premating (temporal, sexual, mechanical (I), and mechanical (II)) and three postmating (oviposition success, fecundity, and fertility) barriers using experimental approaches and, for first time, we investigated the mechanisms causing mechanical isolation, which is the strongest reproductive barrier in ischnurans. The findings of the present study support the notion that premating barriers are generally strong and contribute significantly to total reproductive isolation in young lineages (65-98%), although they never solely lead to complete isolation. Asymmetry was generally stronger in premating than in postmating barriers, and was driven mostly through asymmetry in mechanical isolation, which is caused by morphological divergence of secondary sexual appendages. We found that barriers act multiplicatively in all species combinations tested, with the exception of sexual isolation, which was not detected. Our results are consistent with a recent allopatric speciation scenario driven by differences in male anal appendages, either impeding copulation or affecting female preferences. Taken together, the results from this and previous studies in diverse odonate genera suggest that premating barriers have evolved rapidly in ischnuran damselflies and, although reproductive isolation in ischnurans is more commonly the result of several barriers acting together, morphological divergence of secondary sexual appendages appears to be a common factor facilitating premating isolation in this group.(c) 2014 The Linnean Society of London, Biological Journal of the Linnean Society, 2014, 113, 485-496.
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| 5. |
- Serra-Musach, Jordi, et al.
(författare)
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Cancer network activity associated with therapeutic response and synergism
- 2016
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Ingår i: Genome Medicine. - : BIOMED CENTRAL LTD. - 1756-994X. ; 8:88
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Tidskriftsartikel (refereegranskat)abstract
- Background: Cancer patients often show no or only modest benefit from a given therapy. This major problem in oncology is generally attributed to the lack of specific predictive biomarkers, yet a global measure of cancer cell activity may support a comprehensive mechanistic understanding of therapy efficacy. We reasoned that network analysis of omic data could help to achieve this goal. Methods: A measure of "cancer network activity" (CNA) was implemented based on a previously defined network feature of communicability. The network nodes and edges corresponded to human proteins and experimentally identified interactions, respectively. The edges were weighted proportionally to the expression of the genes encoding for the corresponding proteins and relative to the number of direct interactors. The gene expression data corresponded to the basal conditions of 595 human cancer cell lines. Therapeutic responses corresponded to the impairment of cell viability measured by the half maximal inhibitory concentration (IC50) of 130 drugs approved or under clinical development. Gene ontology, signaling pathway, and transcription factor-binding annotations were taken from public repositories. Predicted synergies were assessed by determining the viability of four breast cancer cell lines and by applying two different analytical methods. Results: The effects of drug classes were associated with CNAs formed by different cell lines. CNAs also differentiate target families and effector pathways. Proteins that occupy a central position in the network largely contribute to CNA. Known key cancer-associated biological processes, signaling pathways, and master regulators also contribute to CNA. Moreover, the major cancer drivers frequently mediate CNA and therapeutic differences. Cell-based assays centered on these differences and using uncorrelated drug effects reveals novel synergistic combinations for the treatment of breast cancer dependent on PI3K-mTOR signaling. Conclusions: Cancer therapeutic responses can be predicted on the basis of a systems-level analysis of molecular interactions and gene expression. Fundamental cancer processes, pathways, and drivers contribute to this feature, which can also be exploited to predict precise synergistic drug combinations.
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| 6. |
- Niemi, MEK, et al.
(författare)
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- 2021
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swepub:Mat__t
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