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Plant DNA: Contents and Systematics
Published in S. K. Dutta, 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
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.
Anticipatory and Compensatory Postural Adjustments in Response to Dynamic Platform Perturbation during a Forward Step
Published in Journal of Motor Behavior, 2023
Yun Wang, Kazuhiko Watanabe, Tadayoshi Asaka
Support surface perturbations triggered complex coordination of the leg and trunk muscles to take a step. Changes of anticipatory muscle activation in the trunk segment were predominantly in the C indices in the APA1 interval, suggesting that the RA-ES muscle pair was both activated and participants used a co-contraction strategy to increase upright stability. In contrast, the R indices of the shank muscles were pronounced in the whole APA intervals. Also, the R indices of the thigh segment were predominantly in the APA3 interval. Support surface perturbations displaced the body COM in the opposite direction to the feet. Forward surface perturbations induced backward postural sway, whereas backward translations resulted in body sway to forward. In the FS condition, the trunk segment showed a significantly larger C value than the BS condition in the APA1 interval. The co-contraction of the RA-ES muscle pair could reverse the trunk excursion to counterbalance inertial forces. This finding is consistent with previous studies reporting that muscle co-contractions increased the joint stiffness and facilitated the quick movement (Asaka & Wang, 2011; Lee et al., 2006; Wang et al., 2016). In response to a forward perturbation, co-activating muscles made the body more rigid for postural stability to resist external forces to take a step.