Investigating sea turtle migration using DNA markers.

The past year has seen a further marshaling of genetic evidence for 'natal homing' in several species of marine turtles, a phenomenon wherein females, upon reaching sexual maturity, exhibit a propensity to return to nest at or near the respective beaches upon which they hatched some two or more decades earlier. This genetics-based inference stems from the strong spatial patterning observed in mitochondrial DNA lineages among nesting sites. Rookery-specific mitochondrial DNA markers are now being employed to monitor the natal sources of individuals captured at other phases of the life cycle, and the genetic findings have important conservation ramifications

Genetic structure of Atlantic and Gulf of Mexico populations of sea bass, menhaden, and sturgeon: Influence of zoogeographic factors and life-history patterns

To assess the influence of zoogeographic factors and life-history parameters (effective population size, generation length, and dispersal) on the evolutionary genetic structure of marine fishes in the southeastern USA, phylogeographic patterns of mitochondrial DNA (mtDNA) were compared between disjunct Atlantic and Gulf of Mexico populations in three coastal marine fishes whose juveniles require an estuarine or freshwater habitat for development. Black sea bass (Centropristis striata), menhaden (Brevoortia tyrannus and B. patronus) and sturgeon (Acipenser oxyrhynchus) samples were collected between 1986 and 1988. All species showed significant haplotype frequency differences between the Atlantic and Gulf, but the magnitude and distribution of mtDNA variation differed greatly among these taxa: sea bass showed little within-region mtDNA polymorphism and a clear phylogenetic distinction between the Atlantic and Gulf; menhaden showed extensive within-region polymorphism and a paraphyletic relationship between Atlantic and Gulf populations; and sturgeon exhibited very low mtDNA diversity both within regions and overall. Evolutionary effective sizes of the female populations (Nf(e)) estimated from the mtDNA data ranged from Nf(e) = 50 (Gulf of Mexico sturgeon) to Nf(e) = 800 000 (Atlantic menhaden), and showed a strong rank-order agreement with the current-day census sizes of these species. The relationship between Nf(e) and the estimated times of divergence (t) among mtDNA lineages (from conventional clock calibrations) predicts the observed phylogenetic distinction between Atlantic and Gulf sea bass, as well as the paraphyletic pattern in menhaden, provided the populations have been separated by the same long-standing zoogeographic barriers thought to have influenced other coastal taxa in the southeastern USA. However, vicariant scenarios alone cannot explain other phylogenetic aspects of the menhaden (and sturgeon) mtDNA data and, for these species, recent gene flow between the Atlantic and Gulf coasts is strongly implicated. These data are relevant to management and conservation issues for these species. © 1990 Springer-Verlag

Hybridization among the ancient mariners: characterization of marine turtle hybrids with molecular genetic assays.

Reports of hybridization between marine turtle species (family Cheloniidae) have been difficult to authenticate based solely on morphological evidence. Here we employ molecular genetic assays to document the sporadic, natural occurrence of viable interspecific hybrids between species representing four of the five genera of cheloniid sea turtles. Using multiple DNA markers from single-copy nuclear loci, eight suspected hybrids (based on morphology) were confirmed to be the products of matings involving the loggerhead turtle (Caretta caretta) x Kemp's ridley (Lepidochelys kempii) (N = 1 specimen), loggerhead turtle x hawksbill (Eretmochelys imbricata) (N = 2), loggerhead turtle x green turtle (Chelonia mydas) (N = 4), and green turtle x hawksbill (N = 1). Molecular markers from mitochondrial DNA permitted identification of the maternal parental species in each cross. The species involved in these hybridization events represent evolutionary lineages thought to have separated 10-75 million years ago (mya) and thus may be among the oldest vertebrate lineages capable of producing viable hybrids in nature. In some cases, human intervention with the life cycles of marine turtles (e.g., through habitat alteration, captive rearing, or attempts to establish new breeding sites) may have increased the opportunities for interspecific hybridization

The Near-Sun Streamer Belt Solar Wind: Turbulence and Solar Wind Acceleration

The fourth orbit of Parker Solar Probe (PSP) reached heliocentric distances down to 27.9 Rs, allowing solar wind turbulence and acceleration mechanisms to be studied in situ closer to the Sun than previously possible. The turbulence properties were found to be significantly different in the inbound and outbound portions of PSP's fourth solar encounter, likely due to the proximity to the heliospheric current sheet (HCS) in the outbound period. Near the HCS, in the streamer belt wind, the turbulence was found to have lower amplitudes, higher magnetic compressibility, a steeper magnetic field spectrum (with spectral index close to -5/3 rather than -3/2), a lower Alfv\'enicity, and a "1/f" break at much lower frequencies. These are also features of slow wind at 1 au, suggesting the near-Sun streamer belt wind to be the prototypical slow solar wind. The transition in properties occurs at a predicted angular distance of ~4{\deg} from the HCS, suggesting ~8{\deg} as the full-width of the streamer belt wind at these distances. While the majority of the Alfv\'enic turbulence energy fluxes measured by PSP are consistent with those required for reflection-driven turbulence models of solar wind acceleration, the fluxes in the streamer belt are significantly lower than the model predictions, suggesting that additional mechanisms are necessary to explain the acceleration of the streamer belt solar wind

Conclusive quantum steering with superconducting transition edge sensors

Quantum steering allows two parties to verify shared entanglement even if one measurement device is untrusted. A conclusive demonstration of steering through the violation of a steering inequality is of considerable fundamental interest and opens up applications in quantum communication. To date all experimental tests with single photon states have relied on post-selection, allowing untrusted devices to cheat by hiding unfavourable events in losses. Here we close this "detection loophole" by combining a highly efficient source of entangled photon pairs with superconducting transition edge sensors. We achieve an unprecedented ~62% conditional detection efficiency of entangled photons and violate a steering inequality with the minimal number of measurement settings by 48 standard deviations. Our results provide a clear path to practical applications of steering and to a photonic loophole-free Bell test.Comment: Preprint of 7 pages, 3 figures; the definitive version is published in Nature Communications, see below. Also, see related experimental work by A. J. Bennet et al., arXiv:1111.0739 and B. Wittmann et al., arXiv:1111.076

Wandering behaviour prevents inter and intra oceanic speciation in a coastal pelagic fish

Small pelagic fishes have the ability to disperse over long distances and may present complex evolutionary histories. Here, Old World Anchovies (OWA) were used as a model system to understand genetic patterns and connectivity of fish between the Atlantic and Pacific basins. We surveyed 16 locations worldwide using mtDNA and 8 microsatellite loci for genetic parameters, and mtDNA (cyt b; 16S) and nuclear (RAG1; RAG2) regions for dating major lineage-splitting events within Engraulidae family. The OWA genetic divergences (0-0.4%) are compatible with intra-specific divergence, showing evidence of both ancient and contemporary admixture between the Pacific and Atlantic populations, enhanced by high asymmetrical migration from the Pacific to the Atlantic. The estimated divergence between Atlantic and Pacific anchovies (0.67 [0.53-0.80] Ma) matches a severe drop of sea temperature during the Gunz glacial stage of the Pleistocene. Our results support an alternative evolutionary scenario for the OWA, suggesting a coastal migration along south Asia, Middle East and eastern Africa continental platforms, followed by the colonization of the Atlantic via the Cape of the Good Hope.Portuguese Foundation for Science & Technology (FCT) [SFRH/BD/36600/2007]; FCT [UID/MAR/04292/2013, SFRH/BPD/65830/2009]; FCT strategic plan [UID/Multi/04326/2013]info:eu-repo/semantics/publishedVersio

Cytotoxic Interactive Effects of Dentin Bonding Components on Mouse Fibroblasts

Previous studies have shown a wide range of pulpal reactions to dentin bonding systems and a poor correlation between in vitro and in vivo toxicity of dentin bonding agents. Because dentin bonding agents are composed of multiple components which may diffuse through dentin, we hypothesized that these components may cause cytotoxicity through interactive (synergistic) effects. We investigated the cytotoxicities of four dentin bonding components-HEMA, Bis-GMA, TEGDMA, and UDMA-and interactive effects for three binary combinations of the dentin bonding components-HEMA and Bis-GMA, Bis-GMA and TEGDMA, and TEGDMA and UDMA. Cytotoxicities to Balb/c 3T3 mouse fibroblasts were measured by the MTT assay. Concentrations which caused 50% toxicity compared with controls (TC50 values) were compared, and the interactive effects were determined by evaluation of the differences between observed and expected MTT activities of the cells. The ranks of toxicity of the dentin bonding components in terms of TC50 values were as follows: Bis-GMA > UDMA > TEGDMA >>> HEMA (least toxic) after 24- and 72-hour exposures. As binary combinations, the three combinations of dentin bonding components interacted in three ways—synergism, additivism, and antagonism-which were influenced by the concentrations of both components. The longer period of exposure resulted in a significant increase in the cytotoxicity of the dentin bonding components and combinations. The findings indicate that both exposure time and the interactions between the dentin bonding components may be important parameters in determining the cytotoxicity of dentin bonding agents in vivo.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/66489/2/10.1177_00220345950740091601.pd

Spectral quantification of nonlinear behaviour of the nearshore seabed and correlations with potential forcings at Duck, N.C., U.S.A

Local bathymetric quasi-periodic patterns of oscillation are identified from monthly profile surveys taken at two shore-perpendicular transects at the USACE field research facility in Duck, North Carolina, USA, spanning 24.5 years and covering the swash and surf zones. The chosen transects are the two furthest (north and south) from the pier located at the study site. Research at Duck has traditionally focused on one or more of these transects as the effects of the pier are least at these locations. The patterns are identified using singular spectrum analysis (SSA). Possible correlations with potential forcing mechanisms are discussed by 1) doing an SSA with same parameter settings to independently identify the quasi-periodic cycles embedded within three potentially linked sequences: monthly wave heights (MWH), monthly mean water levels (MWL) and the large scale atmospheric index known as the North Atlantic Oscillation (NAO) and 2) comparing the patterns within MWH, MWL and NAO to the local bathymetric patterns. The results agree well with previous patterns identified using wavelets and confirm the highly nonstationary behaviour of beach levels at Duck; the discussion of potential correlations with hydrodynamic and atmospheric phenomena is a new contribution. The study is then extended to all measured bathymetric profiles, covering an area of 1100m (alongshore) by 440m (cross-shore), to 1) analyse linear correlations between the bathymetry and the potential forcings using multivariate empirical orthogonal functions (MEOF) and linear correlation analysis and 2) identify which collective quasi-periodic bathymetric patterns are correlated with those within MWH, MWL or NAO, based on a (nonlinear) multichannel singular spectrum analysis (MSSA). (...continued in submitted paper)Comment: 50 pages, 3 tables, 8 figure

The Radial Dependence of Proton-scale Magnetic Spectral Break in Slow Solar Wind during PSP Encounter 2

International audienceMagnetic field fluctuations in the solar wind are commonly observed to follow a power-law spectrum. Near proton-kinetic scales, a spectral break occurs that is commonly interpreted as a transition to kinetic turbulence. However, this transition is not yet entirely understood. By studying the scaling of the break with various plasma properties, it may be possible to constrain the processes leading to the onset of kinetic turbulence. Using data from the Parker Solar Probe, we measure the proton-scale break over a range of heliocentric distances, enabling a measurement of the transition from inertial to kinetic-scale turbulence under various plasma conditions. We find that the break frequency f(b) increases as the heliocentric distance r decreases in the slow solar wind following a power law of f(b) similar to r(-1.11). We also compare this to the characteristic plasma ion scales to relate the break to the possible physical mechanisms occurring at this scale. The ratio f(b)/f(c) (f(c) for Doppler-shifted ion cyclotron resonance scale) is close to unity and almost independent of plasma beta(p). While f(b)/f(p) (f(p) for Doppler-shifted proton thermal gyroradius) increases with beta(p) approaching to unity at larger beta(p), f(b)/f(d) (f(d) for Doppler-shifted proton inertial length) decreases with beta(p) from unity at small beta(p). Due to the large comparable Alfven and solar wind speeds, we analyze these results using both the standard and modified Taylor hypotheses, demonstrating the robust statistical results