Genome-wide association study identifies novel breast cancer susceptibility loci

Breast cancer exhibits familial aggregation, consistent with variation in genetic susceptibility to the disease. Known susceptibility genes account for less than 25% of the familial risk of breast cancer, and the residual genetic variance is likely to be due to variants conferring more moderate risks. To identify further susceptibility alleles, we conducted a two-stage genome-wide association study in 4,398 breast cancer cases and 4,316 controls, followed by a third stage in which 30 single nucleotide polymorphisms (SNPs) were tested for confirmation in 21,860 cases and 22,578 controls from 22 studies. We used 227,876 SNPs that were estimated to correlate with 77% of known common SNPs in Europeans at r2 > 0.5. SNPs in five novel independent loci exhibited strong and consistent evidence of association with breast cancer (P < 10(-7)). Four of these contain plausible causative genes (FGFR2, TNRC9, MAP3K1 and LSP1). At the second stage, 1,792 SNPs were significant at the P < 0.05 level compared with an estimated 1,343 that would be expected by chance, indicating that many additional common susceptibility alleles may be identifiable by this approach.     

Spatial organization of northern flying squirrels, Glaucomys sabrinus: territoriality in females?

We determined home-range overlap among northern flying squirrels ( Glaucomys sabrinus ) to assess their spatial organization. We found extensive home-range overlap among females, and though this overlap could reflect social behavior, we found no evidence of attraction among females, with only one instance of den-sharing. Instead, our results suggest that females share foraging areas but may be territorial in portions of the home range, especially around den trees and during young-rearing. Home-range overlap could also result from the extrinsic effect of forest fragmentation due to timber harvest, which might impede dispersal and force squirrels to cluster on remaining fragments of suitable habitat. Determinamos el sobrelapamiento del rango hogare&ntilde;o entre las ardillas voladoras del norte ( Glaucomys sabrinus ) para evaluar su organizaci&oacute;n espacial. Encontramos un extenso sobrelapamientos en los rangos hogare&ntilde;os entre las hembras; aunque esto podr&iacute;a reflejar su comportamiento social, no encontramos evidencia de atracci&oacute;n entre hembras, y en s&oacute;lo un caso compartieron su guarida. Vienen su lugar, nuestros resultados sugieren que las hembras comparten &aacute;reas de forrajeo pero pueden ser territoriales en ciertas partes de su rango hogare&ntilde;o, particularmente cerca de los &aacute;rboles donde tienen guaridas y cuando tienen cr&iacute;a. El sobrelapamiento del rango hogare&ntilde;o tambi&eacute;n podr&iacute;a ser el resultado del efecto extr&iacute;nseco de la fragmentaci&oacute;n forestal debido a la tala de madera, el cual podr&iacute;a impedir la dispersi&oacute;n y forzar a las ardillas a agruparse en fragmentos de h&aacute;bitat adecuado que queden.     

Different life histories of brook trout populations invading mid-elevation and high-elevation cutthroat trout streams in Colorado

Brook Trout ( Salvelinus fontinalis ), native to eastern North America, have invaded many montane cold-water systems of western North America, and these invasions are implicated in the decline of native cutthroat trout ( Oncorhynchus clarki ). If fisheries biologists are to be effective in managing brook trout invasions, demographic models that predict invasion success will need to incorporate life history variation in different environments. We tested whether brook trout populations invading streams at 2 different elevations varied in life history characteristics that influence population dynamics and potential invasion success. In the high-elevation stream (3195 m), water temperatures were colder and brook trout apparently grew more slowly (i.e., had shorter lengths-at-age), became sexually mature 2 years later, and had life spans 2 to 3 times longer than those in the mid-elevation stream (2683 m). This flexibility in life history may allow brook trout to maximize their chance of establishment and invasion success among elevations. We propose that in mid-elevation streams fast growth and early maturity maximize fitness and can lead to rapid establishment and high population growth rates. In high-elevation streams, slow growth, later maturity, and a long reproductive life span may allow brook trout to successfully establish populations in these marginal habitats where recruitment is often poor.     

A comprehensive ecological land classification for Utah's West Desert

Land managers and scientists need context in which to interpolate between or extrapolate beyond discrete field points in space and time. Ecological classification of land (ECL) is one way by which these relationships can be made. Until regional issues emerged and calls were made for ecosystem management (EM), each land management institution chose its own ECLs. The need for economic efficiency and the increasing availability of geographic information systems (GIS) compel the creation of a national ECL so that communication across ownership boundaries can occur. ECOMAP, an 8-level, top-down, nested, hierarchical, multivariable approach designed to solve this problem has been endorsed by the Federal Geographic Data Committee. While the coarsest, upper 4 levels of ECOMAP have been produced for the entire U.S., the task of completing the 4 finer-grained levels has been left to local practitioners. We tried to apply the suggestions of ECOMAP for completing an ECL for a 4.5-million-hectare area centered in western Utah. Due to the lack of complete and consistent sets of spatial databases suggested as necessary by ECOMAP for completing the ECL for this area, we developed alternatives to complete the ECL using extant information. We stressed 1 dominant landscape feature per hierarchical level, using repeatable protocols to identify landscape units. We added 2 additional levels below the 8 suggested by ECOMAP. Ecological sites (ESs), the 9th level, are designed to overcome the nestedness of ECOMAP that we found prevented us from using important data on ESs already available from the Natural Resources Conservation Service. Vegetation stands (VSs), the 10th and finest-grain level, are subdivisions of individual polygons of ESs based on differences in disturbance histories that have led to differing current vegetation structure and composition. The ECL we created should help federal, state, and private land managers in western Utah more easily communicate about issues that cross ownership boundaries.     

Morphology and taxonomy of Klamath Basin suckers (Catostomidae)

We examined morphology of 4 sucker species (Catostomidae) from Klamath and Rogue River basins, Oregon and California. Different pairs of these species have been suspected of hybridizing, and field biologists have experienced difficulty identifying individuals in some areas. The suite of morphological characters used for initial identification was poorly supported by other morphometric characters but well supported by meristic characters, especially when analyses were restricted geographically. In some species sexual dimorphism was evident, with males having longer pectoral fins and females having longer pre-anal counts and measurements. Each species showed geographic differentiation, either between the Lost River subbasin and other Klamath subbasins or between Klamath and Rogue basins. Classification was most difficult for Catostomus snyderi , which was frequently misclassified as all other species, but especially as Chasmistes brevirostris . Despite this, the 2 species are ecologically segregated in the upper subbasins with lake-spawning Ch. brevirostris spatially segregated and river-spawning Ch. brevirostris temporally segregated from river-spawning C. snyderi . We discuss the possibility that a large-headed, thin-lipped species has become extinct in Upper Klamath Lake and alternatively suggest that the form could represent an ecophenotype of Ch. brevirostris that is no longer produced in hypereutrophic Upper Klamath Lake.     

Disturbance of lekking Lesser Prairie-Chickens ( Tympanuchus pallidicinctus ) by Ring-necked Pheasants ( Phasianus colchicus )

Lesser Prairie-Chicken ( Tympanuchus pallidicinctus ) populations have experienced dramatic rangewide declines (up to 92%) since settlement of the Great Plains. This decline has been attributed to changes in land-use practices, such as conversion of native rangelands to intensive agriculture and increased grazing pressure. These changes may increase the impact of interspecific competition on populations. We documented disturbance of lekking Lesser Prairie-Chickens by Ring-necked Pheasants ( Phasianus colchicus ). Future management and research should take into account possible impacts to Lesser Prairie-Chickens during the breeding season.     

Hyobranchial apparatus of the Cryptobranchoidea (Amphibia)

This report is a comparative study of the hyobranchial skeleton of the three species in the family Cyptobranchidae and four species of the family Hynobiidae, all of which are figured. Anatomical differences between the cryptobranchids and their relationship to hynobiids are noted and discussed. Reference is made to a relationship that may exist between these families and other salamander families, particularly the possible relationship of the Hynobiidae to the super families Ambystomatoidea or possibly Plethodontoidea.     

A habitat suitability model for pygmy rabbits ( Brachylagus iIdahoensis ) in southeastern Idaho

A habitat suitability model was developed for pygmy rabbit ( Brachylagus idahoensis ) habitat on the Idaho National Engineering and Environmental Laboratory (INEEL) in southeastern Idaho. Suitable pygmy rabbit areas were characterized by greater cover and density of total shrubs and big sagebrush ( Artemisia tridentata ), as well as greater forb cover. Soil texture also played an important role in distinguishing suitable pygmy rabbit areas from nonuse sites. Principal components analysis (PCA) of several vegetation variables and soil texture was used to develop a habitat suitability model for pygmy rabbit habitat. This model, which can be used to successfully distinguish between pygmy rabbit use and nonuse areas on the INEEL, has the potential for use throughout the pygmy rabbits range.     

In germ cells of mouse embryonic ovaries, the decision to enter meiosis precedes premeiotic DNA replication

The transition from mitosis to meiosis is a defining juncture in the life cycle of sexually reproducing organisms. In yeast, the decision to enter meiosis is made before the single round of DNA replication that precedes the two meiotic divisions. We present genetic evidence of an analogous decision point in the germ line of a multicellular organism. The mouse Stra8 gene is expressed in germ cells of embryonic ovaries, where meiosis is initiated, but not in those of embryonic testes, where meiosis does not begin until after birth. Here we report that in female embryos lacking Stra8 gene function, the early, mitotic development of germ cells is normal, but these cells then fail to undergo premeiotic DNA replication, meiotic chromosome condensation, cohesion, synapsis and recombination. Combined with previous findings, these genetic data suggest that active differentiation of ovarian germ cells commences at a regulatory point upstream of premeiotic DNA replication.