The genome of the social amoeba Dictyostelium discoideum is known to have a very high density of microsatellite repeats, including thousands of triplet microsatellite repeats in coding regions that apparently code for long runs of single amino acids. We used a mutation accumulation study to see if unusually high microsatellite mutation rates contribute to this pattern. There was a modest bias toward mutations that increase repeat number, but because upward mutations were smaller than downward ones, this did not lead to a net average increase in size. Longer microsatellites had higher mutation rates than shorter ones, but did not show greater directional bias. The most striking finding is that the overall mutation rate is the lowest reported for microsatellites: $1 3 10 À6 for 10 dinucleotide loci and 6 3 10 À6 for 52 trinucleotide loci (which were longer). High microsatellite mutation rates therefore do not explain the high incidence of microsatellites. The causal relation may in fact be reversed, with low mutation rates evolving to protect against deleterious fitness effects of mutation at the numerous microsatellites.M ICROSATELLITES, also known as simple sequence repeats, are long stretches of a short (1-6 bp), tandemly repeated DNA unit, such as the motif CAA repeated 20 times. Microsatellites are common throughout eukaryotic genomes and their lengths are often highly polymorphic, making them powerful markers for use in genetic mapping
The use of laser annealing in the preparation of a clean, well-ordered Ni(001) surface has been investigated. The surface was cleaned by argon ion bombardment and subsequently irradiated with the fundamental output of a high power, Q-switched ruby laser. The laser treated surface was characterized by use of Auger electron spectroscopy and both conventional and spin-polarized LEED, and the data compared to that from a surface prepared by thermal annealing. Laser irradiation of a sputtered surface at energy densities of ∼0.8 J cm−2 leads to complete removal of residual argon without segregation of carbon or other contaminants at the surface. However, irradiation at an elevated temperature ∼200 °C is required to obtain a well-ordered surface. At elevated temperatures, laser annealing provides a surface with cleanness and surface order comparable to that obtained by conventional thermal annealing.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.