Mechanisms of action and co-optive evolution for hypervariable courtship pheromones in plethodontid salamanders.

Pheromones are an important type of chemical cue used by most animals to convey information between individuals. For more than 100 million years, male plethodontid salamanders have utilized a system of non-volatile, proteinaceous pheromones to regulate female mating behavior and receptivity. One of these pheromone components, Plethodontid Modulating Factor (PMF), is a hypervariable protein related to the three-finger protein (TFP) superfamily. Previous studies revealed that PMF persists as a rapidly evolving multi-isoform mixture. However, many characteristics of PMF as a pheromone remained undetermined, including gene structure and transcriptional regulation, translational regulation, protein structure, evolutionary mechanisms, and the isoform effects on female behavior and neurophysiology. Therefore, the broad aim of this dissertation was to characterize the mechanisms of action and evolution for PMF using the red-legged salamander, Plethodon shermani. The molecular and proteomic diversity of PMF was determined by RT-PCR and mass spectroscopy. The PMF complex is the product of at least 13 gene duplications in 3 gene classes containing highly conserved 5’ and 3’ untranslated regions (UTRs). These UTRs are bound by cold inducible RNA binding protein, which likely plays a key role in coordinating expression of the many diverse PMF isoforms during gland development. Using mass spectroscopy and multidimensional NMR, the 3D structure of the most abundant PMF isoform was determined to have a novel structure compared to all other TFPs. In particular, an altered disulfide bonding pattern promoted greater backbone flexibility in the most rapidly evolving segments of PMF to possibly enhance male pheromone and female receptor interactions. Functional assays testing different mixtures of PMF isoforms revealed that isoform diversity is a key requirement for increasing female receptivity, likely through synergistic interactions in the vomeronasal organ and/or the brain. Examination of pheromones in a different plethodontid species (P. cinereus) revealed that the majority of PMF duplications occurred within the last ~20 million years. In summary, in response to female sexual selection, the PMF gene complex has evolved through an unusual disjunctive evolutionary process as part of a birth-and-death model of gene evolution to permit coordinated expression of dozens of flexible proteins that synergistically function to regulate female behavior

Consistency of parity-violating pion-nucleon couplings extracted from measurements in 18F and 133Cs

The recent measurement of the nuclear anapole moment of 133Cs has been interpreted to yield a value of the weak pion-nucleon coupling H_pi^1 which contradicts the upper limit from the 18F experiments. We argue that because of the sensitivity of the anapole moment to H_rho^0 in the odd proton nucleus 133Cs, there is a combination of weak meson-nucleon couplings which satisfies both experiments and which is (barely) in agreement with theory. In addition, the anapole moment measurement in 205Tl gives a constraint which is inconsistent with the value from 133Cs, calling into question the theory of nuclear anapole moments. We argue that measurements of directional asymmetry in n+p-->d+gamma and in the photo-disintegration of the deuteron by circularly polarized photons, combined with results from pp scattering, would determine H_pi^1 and several other weak meson-nucleon couplings in a model-independent way.Comment: 9 pages, RevTeX, 1 figure, eps, submitted to Phys. Rev.

The Locational Impact of Wal-Mart Entrance: A Panel Study of the Retail Trade Sector in West Virginia

This paper examines the retail trade sector in 14 West Virginia counties from 1989 through 1996. A series of random effects models are tested on these panel data to measure the effect of the entrance of Wal- Mart stores in the county and in adjacent counties, and business cycle effects. This paper differs from earlier research in that it controls for endogeneity in the entrance decision of Wal-Mart in faster growing counties. This research finds a dramatic net increase in employment and wages in the Retail Trade sector (SIC 52) and a mild increase in the number of firms. The study finds a per capita wage increase in this industry, which is surprising but small. The paper concludes with further research recommendations.