Structural basis for sequence specific DNA binding and protein dimerization of HOXA13.

The homeobox gene (HOXA13) codes for a transcription factor protein that binds to AT-rich DNA sequences and controls expression of genes during embryonic morphogenesis. Here we present the NMR structure of HOXA13 homeodomain (A13DBD) bound to an 11-mer DNA duplex. A13DBD forms a dimer that binds to DNA with a dissociation constant of 7.5 nM. The A13DBD/DNA complex has a molar mass of 35 kDa consistent with two molecules of DNA bound at both ends of the A13DBD dimer. A13DBD contains an N-terminal arm (residues 324 - 329) that binds in the DNA minor groove, and a C-terminal helix (residues 362 - 382) that contacts the ATAA nucleotide sequence in the major groove. The N370 side-chain forms hydrogen bonds with the purine base of A5* (base paired with T5). Side-chain methyl groups of V373 form hydrophobic contacts with the pyrimidine methyl groups of T5, T6* and T7*, responsible for recognition of TAA in the DNA core. I366 makes similar methyl contacts with T3* and T4*. Mutants (I366A, N370A and V373G) all have decreased DNA binding and transcriptional activity. Exposed protein residues (R337, K343, and F344) make intermolecular contacts at the protein dimer interface. The mutation F344A weakens protein dimerization and lowers transcriptional activity by 76%. We conclude that the non-conserved residue, V373 is critical for structurally recognizing TAA in the major groove, and that HOXA13 dimerization is required to activate transcription of target genes

Scanning Electron Microscopy of the Spermatheca of Plethodon Larselli (Amphibia: Plethodontidae): Changes in the Surface Morphology of the Spermathecal Tubule Prior to Ovulation

Spermathecae from eight mature female Larch Mountain salamanders (Plethodon larselli) were used to study cellular changes accompanying the administration of ovulation-inducing pregnant mare serum gonadotropin (PMSG). Animals injected daily with 25 IU of PMSG were sacrificed on day 2 or day 4. Ultrastructural alterations of the spermathecal tubules include an increase in the synthesis and release of product into the lumen and hypertrophy of two epithelial cell types by day 4. One cell type exhibits apocrine blebs and is covered with microvilli; the other contains large spherical vesicles and has only a few, short microvilli on its surface. These changes apparently reflect the spermatheca\u27s response to impending ovulation and its involvement in reactivating the stored sperm

ESTUDIO DE LA TÉCNICA DE PIETRO MORONE CON IMÁGENES A TRAVÉS DE DIVERSAS LONGITUDES DE ONDA

Mediante las técnicas fotográficas más actualizadas, la exploración intensiva y metodológica de las sargas de las puertas de la predela del retablo mayor de la iglesia de Paracuellos de Jiloca (Zaragoza), pintadas por Pietro Morone (1552 -1557), ha sido posible definir la autoría y distinguir dos técnicas pictóricas en el mismo conjunto.Larsen Pehrzon, CM. (2007). ESTUDIO DE LA TÉCNICA DE PIETRO MORONE CON IMÁGENES A TRAVÉS DE DIVERSAS LONGITUDES DE ONDA. http://hdl.handle.net/10251/12312Archivo delegad

A low-cost autonomous rover for polar science

We present the developmental considerations, design, and deployment of an autonomous modular terrestrial rover for ice-sheet exploration that is inexpensive, easy to construct, and allows for instrumentation customization. The total construction cost for this rover is less than USD 3000, approximately one-tenth the cost of existing platforms, and it can be built using facilities frequently available at academic institutions (machine shop, 3-D printer, open-source hardware and software). Instrumentation deployed on this rover can be customized; the rover presented in this study was equipped with a dual-frequency GPS receiver and a digital SLR camera for constructing digital elevation models using structure-from-motion (SfM) photogrammetry. We deployed this prototype rover on the Northeast Greenland Ice Stream to map local variations in snow accumulation and surface topography. The rover conducted four autonomous missions based out of the East Greenland Ice-Core Project (EastGRIP) camp during July 2017, measuring surface elevation transects across the hazardous ice-stream shear margins. During these missions, the rover proved capable of driving over 20 km on a single charge with a drawbar pull of 250 N, sufficient to tow instrumentation of up to 100 kg. The rover also acquired photographs that were subsequently used to construct digital elevation models of a site monitored for spatiotemporal variability in snow accumulation, demonstrating adequate stability for high-resolution imaging applications. Due to its low cost, low-power requirements, and simple modular design, mass deployments of this rover design are practicable. Operation of the rover in hazardous areas circumvents the substantial expense and risk to personnel associated with conventional, crewed deployments. Thus, this rover is an investigatory platform that enables direct exploration of polar environments considered too hazardous for conventional field expeditions.publishedVersio

Suppression of Met signaling by the green tea polyphenol (-)-epigallocatechin-3-gallate (EGCG)

Met is a prognostic indicator of colorectal cancer patient survival. Therapies that target Met may therefore have beneficial outcomes in the clinic. Recently, EGCG was reported to suppress Met activation, although the mechanisms were not elucidated. HCT116 and HT29 human colon cancer cells were used to examine the relationships between Met activation, EGCG treatment, and H₂O₂ generation. At concentrations of 0.5, 1 and 5 μM, EGCG suppressed the activation of Met induced by its ligand, hepatocyte growth factor (HGF). Concentrations of 10 μM EGCG and below generated low amounts of H₂O₂ (5 μM) were required to directly increase the phosphorylation of Met. Moreover, suppression of Met activation by EGCG occurred in the presence or absence of catalase, suggesting that such effects were not an "artifact" of H₂O₂ generated from EGCG in cell culture media. Molecular docking and enzyme kinetic analyses suggested that EGCG is a competitive inhibitor, binding to the kinase domain of Met with a Ki of 3.3 μM EGCG. The downstream effect of EGCG mediated suppression of the Met receptor included decreased signaling to members of the MAPK and PI3KK signaling pathways. Cell proliferation and migration was also significantly inhibited by EGCG. Overall, the data presented in this dissertation support that EGCG is able to suppress HGF-induced Met signaling. These findings demonstrate that EGCG might be a beneficial therapeutic agent in the colon, inhibiting Met signaling and helping to attenuate tumor metastasis