| 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. |
- Gilbert Temu, Stella, 1987-
(författare)
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Lichens in Mountain Rainforests of Tanzania : Studies of Usnea and Calicioids
- 2020
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Lichens occur in various habitats. They often have narrow niches and are sensitive to environmental changes leading to their use as bioindicators of environmental disturbances and conditions; air and heavy metal pollution, agricultural toxins, assessing forest continuity and drought tolerance. Lichenological studies in Africa, particularly in Tanzania, have been scarce, and those available have been mainly based on morphology and chemistry data. The aim of my doctorate was to investigate lichens, in particular Usnea and calicioid lichens in mountain rain forests in Tanzania, using both traditional and molecular approaches.Paper I and II explored Usnea subgenus Eumitria. In paper I, molecular, morphological and chemical methods were utilized. A phylogeny of Eumitria from Tanzania based on a four-markers data set supported monophyly of Eumitria, where sixty-two new sequences were reported. In paper II additional specimens of the Usnea pectinata aggregate from Tanzania and São Tomé and Príncipe were studied, and forty-two specimens were examined by an integrative approach (molecular, morphological, chemical data). The U. pectinata aggregate was monophyletic, containing several subclades, some characterized morphologically and chemically. Paper III and IV focused on calicioids. Paper III summed up earlier information on Tanzanian calicioids along with new discoveries (twenty-six species), with notes on their habitats and distributions. Chaenothecopsis kilimanjaroensis was described as new, Chaenotheca hispidula and Pyrgillus cambodiensis new to Africa: Calicium lenticulare and Chaenothecopsis debilis new to Tanzania. In paper IV, Coniocybe was revised and emended to include along with its type C. furfuracea, also C. brachypoda and C. confusa. A three marker phylogeny was used to infer its phylogenetic position and Coniocybe eufuracea was described as new.This thesis contributes to the knowledge of the lichens in Tanzania and Africa at large by building capacity in lichenology and its applications for future research. It provided integrated data for Usnea species from Africa, adding to the knowledge of this difficult group (only two sequences of Usnea from Africa have previously been published). It provided new information on calicioid lichens in Tanzania and by uncovering a rich diversity in both of the groups studied provided a foundation for further investigations of lichen biodiversity.
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| 3. |
- Temu, Stella G., et al.
(författare)
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Molecular, morphological and chemical variation of the Usnea pectinata aggregate from Tanzania, São Tomé and Príncipe
- 2022
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Ingår i: The Lichenologist. - : Cambridge University Press. - 0024-2829 .- 1096-1135. ; 54:5, s. 291-298
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Tidskriftsartikel (refereegranskat)abstract
- This study investigated the molecular, chemical and morphological variation in the Usnea pectinata aggregate using 42 specimens, 22 from Tanzania and 20 from São Tomé and Príncipe. A total of 31 sequences (13 ITS, 13 nuLSU and 5 RPB1) were generated. The results are presented in two phylogenies: first a three-markers ‘backbone’ phylogeny for the U. pectinata aggregate, where six distinct, strongly supported subclades indicate considerable genetic variation in the dataset; and second, an ITS phylogeny with 47 terminals along with a mapping of morphological and chemistry data. Several well-supported monophyletic clades were recovered in both phylogenies and these may well represent separate species in the complex referred to here as the U. pectinata aggregate. Three morphotypes characterized by axis pigmentation and four by branch shape were noted. Six chemotypes were observed.
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