Plant DNA: Contents and Systematics
S. K. Dutta in DNA Systematics, 2019
This incongruency of organismal complexity or evolutionary status and DNA content has been termed C-value paradox,15 where C stands for constant and refers to the DNA content of unreplicated haploid genome of a species.16 Evidently, this paradox also implies that gain and/or loss of DNA has taken place many times during evolution. The marked differences even among closely related species indicate that C-value is under strong selection pressure and is a “character of fundamental biological significance”,4 and many studies have shown that this value is fairly constant within the limits of a species. Indeed, DNA content per genome has been correlated with various important characters such as mitotic and meiotic cell cycle duration,17,18 minimum generation time and life cycle type,11,19 latitudinal distribution of crop and noncrop species,20,21 radiosensitivity,22 and radiation-induced mutation rates.23
Therapeutics of Artemisia annua
Tariq Aftab, M. Naeem, M. Masroor, A. Khan in Artemisia annua, 2017
Non-glandular, “T” shaped, trichomes are also present along with 10-celled biseriate glandular trichome on leaves, stem, and inflorescence. The morphology and origin of the trichomes have been described in detail for leaves (Duke and Paul,1993) and capitula (Ferreira and Janick, 1995) using light and/or scanning electron microscopy. It is a short day plant, very responsive to photoperiodic stimulus. The critical photoperiod is reported to be about 13.5 daylight hours, but there is a possibility of photoperiod × temperature interaction. The plants flower in early September with the production of mature seeds in October (Janick, 1995). Nuclear DNA content and other karyological characters in the population of A. annua were studied by Torrell and Valles (2001). In their study, the DNA per haploid genome was 1.75pg, the total karyotypic length was 19.58 μm, and the total haploid chromosome set length was 9.74 μm. They also reported that the annual species A. annua, showed the lowest amount of DNA as compared to the other species. It has approximately 35% lower C value than those of the perennial species.
Cancer Biomarkers
Trevor F. Cox in Medical Statistics for Cancer Studies, 2022
The R function concordance() will calculate Harrell's c. For the ESPAC4 multivariate predictor (see Section 5.2), with . The values of c must lie between 0 and 1, but values much less than 0.5 should not happen since indicates no predictive value. It is hard to give a guide to the interpretation of the c value, some say implies a good model and a very good model.
Evidence of variable human Fcγ receptor-Fc affinities across differentially-complexed IgG
Published in mAbs, 2023
Andrew R. Crowley, Matthew R. Mehlenbacher, Mohammad M. Sajadi, Anthony L. DeVico, George K. Lewis, Margaret E. Ackerman
Complexes were formed from equal volumes of 20 µM solutions containing VRC01 in an IgG1 heavy chain and either antigen or anti-human CH1 capture reagent. For the free IgG condition, VRC01 was instead diluted 1:2 in 1× PBS. FcγRIIIa-V158 at 100 μM was injected using 6 μL per injection and injections spaced 90 s apart. These concentrations of macromolecules and FcγR were chosen based on the theoretically complete formation of 10 µM complex following the mixture of 20 µM reagents. This would yield an ITC c value of 10 or greater when calculated as c = n * Ka * [macromolecule], where n is the stoichiometry of the ligand for the macromolecule and Ka is the association constant of the ligand. Temperature was maintained at 25°C and the sample cell mixed at 750 rpm. Measurements were made with a reference power of 6.0 using a MicroCal PEAQ-ITC (Malvern Panalytical).
Cs-131 as an experimental tool for the investigation and quantification of the radiotoxicity of intracellular Auger decays in vitro
Published in International Journal of Radiation Biology, 2023
Pil M. Fredericia, Mattia Siragusa, Ulli Köster, Gregory Severin, Torsten Groesser, Mikael Jensen
The height of the CMs and the sizes of the nuclei were determined by confocal microscopy. A cross section of the 100% confluent CM can be seen in Figure 5. As is evident from the illustration, neighboring cells are so close to each other that their plasma membranes (green) are touching, leaving no space between them. A high cell density is central for the geometry assumed in the SC-value calculations and its verification is important for correct absorbed dose calculations. The average heights of the confluent cell layers were determined to be 10 μm for the HeLa cell culture and 7.5 μm for the V79 cell culture, with an estimated uncertainty of ± 1–2 μm due the variations in cellular height (as evident from Figure 5) and to limitations of the confocal microscopy technique. The cell cultures used for the clonogenic assay had this level, 100%, of confluence, while the cell cultures used for the γH2AX assay were 80% confluent.
Non-linear conversion of HX4 uptake for automatic segmentation of hypoxic volumes and dose prescription
Published in Acta Oncologica, 2018
Ana Ureba, Emely Lindblom, Alexandru Dasu, Johan Uhrdin, Aniek J. G. Even, Wouter van Elmpt, Philippe Lambin, Peter Wersäll, Iuliana Toma-Dasu
Solving Equation (4) leads to two solutions for the C parameter, C = 111.5 mmHg and C = 0.1 mmHg. The larger C value does not fulfil the condition of C ≪ pO2 for high oxygen partial pressures corresponding to normoxia. Furthermore, using this C value will predict a normalised uptake in hypoxic tissues that is at maximum 1.5 times higher than the uptake in the reference region, providing little contrast between hypoxia and normoxia. Hence, using this value for the parameter C will not allow the practical identification of HTVs and C = 111.5 mmHg was discarded. The smaller value of 0.1 mmHg however fulfils C ≪ pO2 and results in a favourable discrimination between uptake values corresponding to hypoxia and normoxia. An illustration of the relationship between the tracer uptake and pO2 described by Equation (1) using the lower value of the solution for the C parameter (0.1 mmHg) is shown in Figure 1.