Significant Strain Variation in the Mutation Spectra of Inbred Laboratory Mice.

Mutation provides the ultimate source of all new alleles in populations, including variants that cause disease and fuel adaptation. Recent whole genome sequencing studies have uncovered variation in the mutation rate among individuals and differences in the relative frequency of specific nucleotide changes (the mutation spectrum) between populations. Although parental age is a major driver of differences in overall mutation rate among individuals, the causes of variation in the mutation spectrum remain less well understood. Here, I use high-quality whole genome sequences from 29 inbred laboratory mouse strains to explore the root causes of strain variation in the mutation spectrum. My analysis leverages the unique, mosaic patterns of genetic relatedness among inbred mouse strains to identify strain private variants residing on haplotypes shared between multiple strains due to their recent descent from a common ancestor. I show that these strain-private alleles are strongly enriched for recent de novo mutations and lack signals of widespread purifying selection, suggesting their faithful recapitulation of the spontaneous mutation landscape in single strains. The spectrum of strain-private variants varies significantly among inbred mouse strains reared under standardized laboratory conditions. This variation is not solely explained by strain differences in age at reproduction, raising the possibility that segregating genetic differences affect the constellation of new mutations that arise in a given strain. Collectively, these findings imply the action of remarkably precise nucleotide-specific genetic mechanisms for tuning the de novo mutation landscape in mammals and underscore the genetic complexity of mutation rate control

The effect of emulsion stabilizers on the rate of solution of silver halide grains

The effects of the emulsion stabilizers, 4-hydroxy- 6-methyl-l ,33a,7-tetraazaindene and l-phenyl-2-tetrazoline- 5-thione on the rate of solution-physical development of a monodisperse AgBr emulsion containing Carey-Lea silver sol were measured at a series of concentrations. A study of the effects of the silver halide solvent, sulfite has been stud ied along with a low-solvent surface developer. It was found that the tetraazaindene definitely had an effect on the rate of solution-physical development, while the l-phenyl-2- tetrazoline- 5-thione did not have a significant effect

Alien Registration- Dumont, Marie L. (Auburn, Androscoggin County)

https://digitalmaine.com/alien_docs/31233/thumbnail.jp

Variability of the H-beta line profiles as an indicator of orbiting bright spots in accretion disks of quasars: a case study of 3C 390.3

Here we show that in the case when double peaked emission lines originate from outer parts of accretion disk, their variability could be caused by perturbations in the disk emissivity. In order to test this hypothesis, we introduced a model of disk perturbing region in the form of a single bright spot (or flare) by a modification of the power law disk emissivity in appropriate way. The disk emission was then analyzed using numerical simulations based on ray-tracing method in Kerr metric and the corresponding simulated line profiles were obtained. We applied this model to the observed H-beta line profiles of 3C 390.3 (observed in the period 1995-1999), and estimated the parameters of both, accretion disk and perturbing region. Our results show that two large amplitude outbursts of the H-beta line observed in 3C 390.3 could be explained by successive occurrences of two bright spots on approaching side of the disk. These bright spots are either moving, originating in the inner regions of the disk and spiralling outwards by crossing small distances during the period of several years, or stationary. In both cases, their widths increase with time, indicating that they most likely decay.Comment: 14 pages, 5 figures, 1 table. Accepted for publication in Ap

The puzzle of the soft X-ray excess in AGN: absorption or reflection?

The 2-10 keV continuum of AGN is generally well represented by a single power law. However, at smaller energies the continuum displays an excess with respect to the extrapolation of this power law, called the ''soft X-ray excess''. Until now this soft X-ray excess was attributed, either to reflection of the hard X-ray source by the accretion disk, or to the presence of an additional comptonizing medium, giving a steep spectrum. An alternative solution proposed by Gierlinski and Done (2004) is that a single power law well represents both the soft and the hard X-ray emission and the impression of the soft X-ray excess is due to absorption of a primary power law by a relativistic wind. We examine the advantages and drawbacks of reflection versus absorption models, and we conclude that the observed spectra can be well modeled, either by absorption (for a strong excess), or by reflection (for a weak excess). However the physical conditions required by the absorption models do not seem very realistic: we would prefer an ''hybrid model''.Comment: 4 pages, 3 figures, abstracts SF2A-2005, published by EDP-Sciences Conference Serie

First results on the diet of the young Atlantic sturgeon Acipenser sturio L., 1758 in the Gironde estuary

Very little is known about the diet of the European sturgeon Acipenser sturio L., 1758 in its natural environment. For juveniles, improved knowledge in this field could lead towards the determination of the species's major feeding habitats in the estuary, in order to then improve their preservation or protection. From May 1998 to March 1999, the stomach contents of 61 juveniles were collected by gastric lavage. The fish were caught during monthly trawling campaigns to monitor sturgeon migration in the Gironde estuary (southwestern France). Specimens were mainly caught during spring and summer in two areas of increased abundance. The gastric lavage method used had been previously tested on Siberian sturgeon Acipenser baerii Brandt, 1869 in captivity. Twelve taxa of prey were found. The highest proportions in number identified consisted of polychaetes, mainly represented by Heteromastus filiformis (Claparede, 1864) in zone 7 and Polydora Bosc, 1802 sp. in zone 1. Crustaceans were the second most abundant group of prey.Se conoce muy poco sobre la dieta del esturión atlántico Acipenser sturio L., 1758 en su medio natural. Para los juveniles, un conocimiento mejorado en este campo podía conducir hacia la determinación de los principales hábitats alimentarios de la especie en el estuario, como preámbulo para su mejor preservación y conservación. Entre mayo de 1998 y marzo de 1999 fueron recogidos los contenidos estomacales de 61 juveniles por lavado gástrico. Los peces fueron capturados durante las campañas mensuales de pesca de arrastre para el seguimiento de la migración del esturión en el estuario del Gironda (suroeste de Francia). Los ejemplares fueron capturados principalmente en primavera y verano en dos áreas de alta abundancia. El método de lavado gástrico utilizado fue probado previamente en cautividad con esturión siberiano Acipenser baerii Brandt, 1869. Se encontraron presas de doce taxones. Las proporciones más altas en número correspondieron a poliquetos, principalmente representados por Heteromastus filiformis (Claparede, 1864) en la zona 7 y Polydora Bosc, 1802 sp. en la zona 1. Los crustáceos fueron el segundo grupo de presas más abundante.Instituto Español de Oceanografí

Rapid Evolution of the Fine-scale Recombination Landscape in Wild House Mouse (Mus musculus) Populations.

Meiotic recombination is an important evolutionary force and an essential meiotic process. In many species, recombination events concentrate into hotspots defined by the site-specific binding of PRMD9. Rapid evolution of Prdm9\u27s zinc finger DNA-binding array leads to remarkably abrupt shifts in the genomic distribution of hotspots between species, but the question of how Prdm9 allelic variation shapes the landscape of recombination between populations remains less well understood. Wild house mice (Mus musculus) harbor exceptional Prdm9 diversity, with \u3e150 alleles identified to date, and pose a particularly powerful system for addressing this open question. We employed a coalescent-based approach to construct broad- and fine-scale sex-averaged recombination maps from contemporary patterns of linkage disequilibrium in nine geographically isolated wild house mouse populations, including multiple populations from each of three subspecies. Comparing maps between wild mouse populations and subspecies reveals several themes. First, we report weak fine- and broad-scale recombination map conservation across subspecies and populations, with genetic divergence offering no clear prediction for recombination map divergence. Second, most hotspots are unique to one population, an outcome consistent with minimal sharing of Prdm9 alleles between surveyed populations. Finally, by contrasting aggregate hotspot activity on the X versus autosomes, we uncover evidence for population-specific differences in the degree and direction of sex dimorphism for recombination. Overall, our findings illuminate the variability of both the broad- and fine-scale recombination landscape in M. musculus and underscore the functional impact of Prdm9 allelic variation in wild mouse populations