A Novel Role for Mc1r in the Parallel Evolution of Depigmentation in Independent Populations of the Cavefish Astyanax mexicanus

The evolution of degenerate characteristics remains a poorly understood phenomenon. Only recently has the identification of mutations underlying regressive phenotypes become accessible through the use of genetic analyses. Focusing on the Mexican cave tetra Astyanax mexicanus, we describe, here, an analysis of the brown mutation, which was first described in the literature nearly 40 years ago. This phenotype causes reduced melanin content, decreased melanophore number, and brownish eyes in convergent cave forms of A. mexicanus. Crosses demonstrate non-complementation of the brown phenotype in F2 individuals derived from two independent cave populations: Pachón and the linked Yerbaniz and Japonés caves, indicating the same locus is responsible for reduced pigmentation in these fish. While the brown mutant phenotype arose prior to the fixation of albinism in Pachón cave individuals, it is unclear whether the brown mutation arose before or after the fixation of albinism in the linked Yerbaniz/Japonés caves. Using a QTL approach combined with sequence and functional analyses, we have discovered that two distinct genetic alterations in the coding sequence of the gene Mc1r cause reduced pigmentation associated with the brown mutant phenotype in these caves. Our analysis identifies a novel role for Mc1r in the evolution of degenerative phenotypes in blind Mexican cavefish. Further, the brown phenotype has arisen independently in geographically separate caves, mediated through different mutations of the same gene. This example of parallelism indicates that certain genes are frequent targets of mutation in the repeated evolution of regressive phenotypes in cave-adapted species

Determination of sin2 θeff w using jet charge measurements in hadronic Z decays

The electroweak mixing angle is determined with high precision from measurements of the mean difference between forward and backward hemisphere charges in hadronic decays of the Z. A data sample of 2.5 million hadronic Z decays recorded over the period 1990 to 1994 in the ALEPH detector at LEP is used. The mean charge separation between event hemispheres containing the original quark and antiquark is measured for bb̄ and cc̄ events in subsamples selected by their long lifetimes or using fast D*'s. The corresponding average charge separation for light quarks is measured in an inclusive sample from the anticorrelation between charges of opposite hemispheres and agrees with predictions of hadronisation models with a precision of 2%. It is shown that differences between light quark charge separations and the measured average can be determined using hadronisation models, with systematic uncertainties constrained by measurements of inclusive production of kaons, protons and A's. The separations are used to measure the electroweak mixing angle precisely as sin2 θeff w = 0.2322 ± 0.0008(exp. stat.) ±0.0007(exp. syst.) ± 0.0008(sep.). The first two errors are due to purely experimental sources whereas the third stems from uncertainties in the quark charge separations

Farm-Level Characteristics of Southern Nebraska Farms/Ranches with Annually-Planted Crops

The information presented in this report represents data collected from farming and ranching operations in the southern two tiers of counties in Nebraska. This study was based on a random sample of 15 1 southern Nebraska farms that have annually-planted crop acreage. Information was obtained for the 1997 crop year. This data set is referred to as the MSU/UNL survey data. From the MSU/UNL survey data, the average size of the farming operations in the survey, in 1997, was 1,3 16 acres. Of these, 856 acres were planted to annual crops, and the remaining 460 acres included 61 acres in fallow, 29 acres in hay, 287 acres in range and pasture, 28 acres in CRP, and 55 acres in other uses. Operation size was largest in the west, due mostly to a large number of range and pasture land acres per operator. Average farm size decreased in the east as range and pasture land acres and acres fallowed per farm both decreased. Acreage planted to annual crops was similar from east to west. Irrigated and dryland grain corn was the predominant crop grown in the survey area. Other major crops included soybeans, sorghum, and winter wheat. An estimated 44 percent of the respondents\u27 cropland acreage was dedicated to corn production. Other annual crops included soybean (21 percent of cropland acreage), sorghum (10 percent of cropland acreage), winter wheat (12 percent of cropland acreage), and minor crops (4 percent of cropland acreage) with most of the remaining cropland in fallow. The distribution of these crops varied across the southern tier of Nebraska counties. Winter wheat was most common in the west and soybean was more prevalent in the east. About 65 percent of total cropland acreage reported was dryland while the remaining 35 percent was irrigated. Significantly more irrigation takes place in the central area. Two-thirds of the operations surveyed reported some type of livestock enterprise. Cattle were the most common type of livestock reported, followed by hogs and sheep. Breeding cattle numbers were greater than feeder cattle numbers. Dairy cattle were rarely reported except in the eastern counties. Producers in the central and eastern counties also reported hog production, with feeder hogs greatly outnumbering breeding animals. Comparisons of acres planted and crop yields from the MSU/UNL survey data to data collected by Nebraska Agricultural Statistics Service (NASS), for the same year, show little differences. Most estimates are within 2 percentage points of each other