54,083 research outputs found
Functional relevance of the newly evolved sperm dynein intermediate chain multigene family in Drosophila melanogaster males.
In many animal species, traits associated with male fitness evolve rapidly. Intersexual conflict and male-male competition have been suggested to drive this rapid evolution. These fast evolutionary dynamics result in elevated rates of amino acid replacement and modification of gene expression attributes. Gene acquisition is another mechanism that might contribute to fitness differences among males. However, empirical evidence of fitness effects associated with newly evolved genes is scarce. The Sdic multigene family originated within the last 5.4 myr in the lineage that leads to D. melanogaster and encodes a sperm dynein intermediate chain presumably involved in sperm motility. The silencing of the Sdic multigene family, followed by the screening of relevant phenotypes, supports the role of the Sdic multigene family in sperm competition. The case of the Sdic multigene family illustrates the flexibility of genetic networks in incorporating lineage-specific gene novelties that can trigger an evolutionary arms race between males
Fermi-Frenet coordinates for space-like curves
We generalize Fermi coordinates, which correspond to an adapted set of
coordinates describing the vicinity of an observer's worldline, to the
worldsheet of an arbitrary spatial curve in a static spacetime. The spatial
coordinate axes are fixed using a covariant Frenet triad so that the metric can
be expressed using the curvature and torsion of the spatial curve. As an
application of Fermi-Frenet coordinates, we show that they allow covariant
inertial forces to be expressed in a simple and physically intuitive way.Comment: 7 page
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