Tracking leatherback turtles (Dermochelys coriacea) during consecutive inter-nesting intervals: Further support for direct transmitter attachment

Over recent years there have been substantial efforts to record and interpret the post-nesting movements of leatherback turtles (Dermochelys coriacea) breeding in tropical regions. Less well documented are the movements undertaken by individual turtles during the breeding season itself, or more specifically between sequential nesting events. Such movements are of interest for two reasons: (1) gravid female leatherbacks may range extensively into the territorial waters and nesting beaches of neighbouring countries, raising questions for conservationists and population ecologists; and (2) the magnitude of movements themselves help elucidate underlying reproductive strategies (e.g. whether to rest near to the nesting or forage extensively). Here, satellite relay data loggers are used (SRDLs) to detail the movements and behaviour of two female leatherback turtles throughout three consecutive inter-nesting intervals in the Commonwealth of Dominica, West Indies. Both near-shore residence and extensive inter-nesting movements were recorded, contrasting previous studies, with movements away from the nesting beach increasing towards the end of the nesting season. Using this behavioural study as a backdrop, the suitability of attaching satellite transmitters directly to the carapace was additionally explored as an alternative approach to conventional harness deployments. Specifically, the principal aims were to (1) gather empirical data on speed of travel and (2) assess dive performance (aerobic dive limit) to enable comparisons with turtles previously fitted with harnesses elsewhere in the Caribbean (n = 6 turtles; Grenada, WI). This produced mixed results with animals bearing directly attached transmitters travelling significantly faster (55.21 km day(-1): SD 6.68) than harnessed individuals (39.80 km day(-1); SD 6.19); whilst no discernable difference in dive performance could be found between the two groups of study animals. (C) 2009 Elsevier B.V. All rights reserved.

Direct versus delayed pathways in strong-field non-sequential double ionization

We report full-dimensionality quantum and classical calculations of double ionization (DI) of laser-driven helium at 390 nm. Good agreement is observed. We identify the relative importance of the two main non-sequential DI pathways, the direct|with an almost simultaneous ejection of both electrons|and the delayed. We find that the delayed pathway prevails at small intensities independently of total electron energy but at high intensities the direct pathway predominates up to a certain upper-limit in total energy which increases with intensity. An explanation for this increase with intensity is provided.

The Role of Direct Presentation by Donor Dendritic Cells in Rejection of Minor Histocompatibility Antigen-Mismatched Skin and Hematopoietic Cell Grafts

Background. The success of transplantation is hampered by rejection of the graft by alloreactive T cells. Donor dendritic cells (DC) have been shown to be required for direct priming of immune responses to antigens from major histocompatibility complex-mismatched grafts. However, for immune responses to major histocompatibility complex-matched, minor histocompatibility (H) antigen mismatched grafts, the magnitude of the T-cell response to directly presented antigens is reduced, and the indirect pathway is more important. Therefore, we aimed to investigate the requirement for donor DC to directly present antigen from minor H antigen mismatched skin and hematopoietic grafts.

Claudin-1 Has Tumor Suppressive Activity and Is a Direct Target of RUNX3 in Gastric Epithelial Cells

BACKGROUND & AIMS: The transcription Factor RUNX3 is a gastric tumor suppressor. Tumorigenic Runx3(-/-) gastric epithelial cells attach weakly to each other, compared with nontumorigenic Runx3(+/+) cells. We alined to identify RUNX3 target genes that promote cell-cell contact to Improve our understanding of RUNX3's role in Suppressing gastric carcinogenesis. METHODS: We compared gene expression profiles of Runx3(+/+) and Runx3(-/-) cells and observed down-regulation of genes associated with cell-cell adhesion in Runx3(-/-) cells. Reporter, mobility shift, and chromatin immunoprecipitation assays were used to examine the regulation of these genes by RUNX3. Tumorigenesis assays and immunohistologic, analyses of human gastric tumors were performed to confirm the role of the candidate genes ill gastric tumor development. RESULTS: Mobility shift and chromatin immunoprecipitation assays revealed that the promoter activity of the gene that encodes the tight Junction protein claudin-1 was up-regulated via the binding of RUNX3 to the RUNX consensus sites. The tumorigenicity of gastric epithelial cells From Runx3(-/-) mice was significantly reduced by restoration of claudin-1 expression, whereas knockdown of claudin-1. increased the tumorigenicity of human gastric cancer cells. Concomitant expression of RUNX3 and claudin-1 was observed in human normal gastric epithelium and cancers. CONCLUSIONS: The tight junction protein claudin-1 has gastric tumor suppressive activity and is a direct transcriptional target of RUNX3. Claudin-1 is down-regulated during the epithelial-mesenchymal transition; RUNX3 might therefore act as a tumor suppressor to antagonize the epithelial-mesenchymal transition.

Comprehensive genomic screens identify a role for PLZF-RAR alpha as a positive regulator of cell proliferation via direct regulation of c-MYC

The t(11; 17)(q23;q21) translocation is associated with a retinoic acid (RA)-insensitive form of acute promyelocytic leukemia (APL), involving the production of reciprocal fusion proteins, promyelocytic leukemia zinc finger-retinoic acid receptor alpha (PLZF-RAR alpha) and RAR alpha-PLZF. Using a combination of chromatin immuno-precipitation promotor arrays (ChIP-chip) and gene expression profiling, we identify novel, direct target genes of PLZF-RAR alpha that tend to be repressed in APL compared with other myeloid leukemias, supporting the role of PLZF-RAR alpha as an aberrant repressor in APL. In primary murine hematopoietic progenitors, PLZF-RAR alpha promotes cell growth, and represses Dusp6 and Cdkn2d, while inducing c-Myc expression, consistent with its role in leukemogenesis. PLZF-RAR alpha binds to a region of the c-MYC promoter overlapping a functional PLZF site and antagonizes PLZF-mediated repression, suggesting that PLZF-RAR alpha may act as a dominant-negative version of PLZF by affecting the regulation of shared targets. RA induced the differentiation of PLZF-RAR alpha-transformed murine hematopoietic cells and reduced the frequency of clonogenic progenitors, concomitant with c-Myc down-regulation. Surviving RA-treated cells retained the ability to be replated and this was associated with sustained c-Myc expression and repression of Dusp6, suggesting a role for these genes in maintaining a self-renewal pathway triggered by PLZF-RAR alpha. (Blood. 2009; 114: 5499-5511)

Origin of Low CO2 Selectivity on Platinum in the Direct Ethanol Fuel Cell

Calculated answer: First-principles calculations have been applied to calculate the energy barrier for the key step in CO formation on a Pt surface (see picture; Pt blue, Pt atoms on step edge yellow) to understand the low CO2 selectivity in the direct ethanol fuel cell. The presence of surface oxidant species such as O (brown bar) and OH (red bar) led to an increase of the energy barrier and thus an inhibition of the key step. © 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

A Spitzer Space Telescope study of SN 2003gd: Still no direct evidence that core-collapse supernovae are major dust factories

We present a new, detailed analysis of late-time mid-infrared observations of the Type II-P supernova (SN) 2003gd. At about 16 months after the explosion, the mid-IR flux is consistent with emission from 4 x 10(-5) M. of newly condensed dust in the ejecta. At 22 months emission from pointlike sources close to the SN position was detected at 8 and 24 mu m. By 42 months the 24 mu m flux had faded. Considerations of luminosity and source size rule out the ejecta of SN 2003gd as the main origin of the emission at 22 months. A possible alternative explanation for the emission at this later epoch is an IR echo from preexisting circumstellar or interstellar dust. We conclude that, contrary to the claim of Sugerman and coworkers, the mid-IR emission from SN 2003gd does not support the presence of 0.02 M. of newly formed dust in the ejecta. There is, as yet, no direct evidence that core-collapse supernovae are major dust factories.