producing hybrid lettuce is prevented by flower structure and usually lead to selfing. based on it, this experiment was carried out to evaluate the performance of different physical and chemical emasculation methods for producing lettuce hybrid seed. a numbers of cultivars with dominant and recessive traits were used as male and female parents, respectively. in the first experiment, physical em...

We report the generation of West Nile virus (WNV) infectious clones for the pathogenic lineage 1 Texas-HC2002 and nonpathogenic lineage 2 Madagascar-AnMg798 strains. The infectious clones exhibited biological properties similar to those of the parental virus isolates. We generated chimeric viruses and found that viral factors within the structural and nonstructural regions of WNV-TX contribute ...

The descendants of immigrants comprise nearly a third of the West German population under the age of 25 years and will soon become a substantial proportion of the native born labor force. Owing to the young age of this group, and a lack of governmental data on parental place of birth, there is currently little research that compares the labor market outcomes of the second generation of differen...

The Seal Nunataks ice shelf (SNIS, ∼743 km in 2013) is an unofficial name for a remnant area between the former Larsen A and Larsen B ice shelves off the northeastern Antarctic Peninsula. Analyses using Landsat 7 ETM+ and Terra ASTER images from 2001 to 13 and ICESat altimetry from 2003 to 09 show it has retreated and thinned following the Larsen A (1995) and Larsen B (2002) disintegrations. De...

Context Understanding the factors determining impacts of roads and how they fragment landscapes limiting movement animals, is key to implement efficient mitigation measures. Aims Here we investigate if road orientation in relation resources, a largely overlooked factor on impact assessments, can influence animals within landscape where water resources are spatially clustered. Methods We evaluat...

Migrating long distances requires time and energy, and may interact with an individual's performance during breeding. These seasonal interactions in migratory animals are best described in populations with disjunct nonbreeding distributions. The black-tailed godwit (Limosa limosa limosa), which breeds in agricultural grasslands in Western Europe, has such a disjunct nonbreeding distribution: Th...

The mechanisms of pigeon homing are still not understood, in particular how they determine their position at unfamiliar locations. The "gravity vector" theory holds that pigeons memorize the gravity vector at their home loft and deduct home direction and distance from the angular difference between memorized and actual gravity vector. However, the gravity vector is tilted by different densities...