Tobacco-smoke exposure indicators and urinary mutagenicity

The protective effect of calcium given orally by gavage with two doses (40 and 80mg/kg body weight) was evaluated against clastogenecity induced by lead acetate with two concentrations (200 and 400mg/kg diet) on bone marrow and spermatocyte cells of mice in vivo. The parameter screened was percentage of chromosomal aberrations with and without gaps and sperm abnormalities. Statistical analyses indicated the protection efficacy of calcium with the high dose rather than the other in both types of mouse cells.The observation from the laboratory tests, dealing that lead acetate can be considered as an environmental genotoxic material. We recommended that it must be administered of calcium (as calcium chloride) as a protective agent to reduce the genotoxic effect of lead in the somatic and germ cells.     

New palladacyclopentadiene complexes containing an N,P-donor setting. Crystal structure of [Pd{C4(COOMe)4}(o-Ph2PC6H4CHNPr)]

The synthesis of palladacyclopentadiene derivatives with the mixed-donor bidentate ligands o-Ph₂PC₆H₄CHNR (N^∧P) has been achieved. The new complexes of general formula [Pd{C₄(COOMe)₄}(o-Ph₂PC₆H₄CHNR)] [R=Me (1), Et (2), ⁱPr (3), ^tBu (4), NHMe (5)] have been prepared by reaction between the precursor [Pd{C₄(COOMe)₄}]_n and the corresponding iminophosphine. The polymer complex [Pd{C₄(COOMe)₄}]_n also reacts with pyridazine (C₄H₄N₂) to give the insoluble dinuclear complex [Pd{C₄(COOMe)₄}(μ-C₄H₄N₂)]₂ (6), which has been successfully employed as precursor in the synthesis of pyridazine-based palladacyclopentadiene complexes. The reaction of 6 with tertiary phosphines yielded complexes containing an N,P-donor setting of formula [Pd{C₄(COOMe)₄}(C₄H₄N₂)(L)] (L=PPh₃ (7), PPh₂Me (8), P(p-MeOC₆H₄)₃ (9), P(p-FC₆H₄)₃ (10)). The new complexes were characterized by partial elemental analyses and spectroscopic methods (IR, ¹H, ¹⁹F and ³¹P NMR). The molecular structure of complex 3 has been determined by a single-crystal diffraction study, showing that the iminophosphine acts as chelating ligand with coordination around the palladium atom slightly distorted from the square-planar geometry.     

Analyzing gene regulation in ascidian embryos: new tools for new perspectives

Ascidians are marine protochordates at the evolutionary boundary between invertebrates and vertebrates. Ascidian larvae provide a simple system for unraveling gene regulation networks underlying the formation of the basic chordate body plan. After being used for over a century as a model for embryological studies, ascidians have become, in the past decade, an increasingly popular organism for studying gene regulation. Part of the renewed appeal of this system is the use of electroporation to introduce transgenic DNAs into developing embryos. This method is considerably more efficient than conventional microinjection assays and permits the simultaneous transformation of hundreds of embryos. Electroporation has allowed the identification and characterization of cis-regulatory DNAs that mediate gene expression in a variety of tissues, including the notochord, tail muscles, CNS, and endoderm. Electroporation has also provided a simple method for misexpressing patterning genes and producing dominant mutant phenotypes. Recent studies have used electroporation to create "knock-out" phenotypes by overexpressing dominant negative forms of particular proteins. Here we review the past and present uses of electroporation in ascidian development, and speculate on potential future uses.     

A calcium-permeable channel activated by muscarinic acetylcholine receptors and InsP3 in developing chick ciliary ganglion neurons

The electrical responses elicited by the muscarinic cholinergic pathway have been studied in cultured embryonic chick ciliary ganglion (CG) neurons. Neurons obtained from E7-E8 ganglia were maintained in serum-free medium for 1 to 3 days. Stimulation with 50 microM muscarine induced depolarizing responses in about 30% of the cells tested. In voltage clamp experiments at a holding potential of -50 mV, an inward current could be recorded in the same percentage of cells in response to muscarinic stimulation. In single channel experiments, with standard physiological solution in the pipette, muscarine transiently activated an inward conducting channel. Cell-attached recordings with 100 mM CaCl(2) in the pipette provided evidence that muscarinic agonists can activate a cationic calcium-permeable channel. Two main conductance levels could be detected, of 2.3+/-0.6 and 5.6+/-0.6 pS, respectively. In excised patches, addition of 5-20 microM inositol 1,4,5-trisphosphate (InsP(3)) to the bath reactivated a channel that could be blocked by heparin and whose characteristics were very similar to those of the channel seen in response to muscarinic stimulation. A channel with similar properties has been previously shown to be activated by basic fibroblast growth factor (bFGF) and InsP(3) in the same preparation.     

Muscle-specific RING finger-1 interacts with titin to regulate sarcomeric M-line and thick filament structure and may have nuclear functions via its interaction with glucocorticoid modulatory element binding protein-1

Signaling from receptor tyrosine kinases (RTKs)* requires the sequential activation of the small GTPases Ras and Rac. Son of sevenless (Sos-1), a bifunctional guanine nucleotide exchange factor (GEF), activates Ras in vivo and displays Rac-GEF activity in vitro, when engaged in a tricomplex with Eps8 and E3b1-Abi-1, a RTK substrate and an adaptor protein, respectively. A mechanistic understanding of how Sos-1 coordinates Ras and Rac activity is, however, still missing. Here, we demonstrate that (a) Sos-1, E3b1, and Eps8 assemble into a tricomplex in vivo under physiological conditions; (b) Grb2 and E3b1 bind through their SH3 domains to the same binding site on Sos-1, thus determining the formation of either a Sos-1-Grb2 (S/G) or a Sos-1-E3b1-Eps8 (S/E/E8) complex, endowed with Ras- and Rac-specific GEF activities, respectively; (c) the Sos-1-Grb2 complex is disrupted upon RTKs activation, whereas the S/E/E8 complex is not; and (d) in keeping with the previous result, the activation of Ras by growth factors is short-lived, whereas the activation of Rac is sustained. Thus, the involvement of Sos-1 at two distinct and differentially regulated steps of the signaling cascade allows for coordinated activation of Ras and Rac and different duration of their signaling within the cell.     

Genome-Wide Association Mapping for Yield and Other Agronomic Traits in an Elite Breeding Population of Tropical Rice (Oryza sativa)

Genome-wide association mapping studies (GWAS) are frequently used to detect QTL in diverse collections of crop germplasm, based on historic recombination events and linkage disequilibrium across the genome. Generally, diversity panels genotyped with high density SNP panels are utilized in order to assay a wide range of alleles and haplotypes and to monitor recombination breakpoints across the genome. By contrast, GWAS have not generally been performed in breeding populations. In this study we performed association mapping for 19 agronomic traits including yield and yield components in a breeding population of elite irrigated tropical rice breeding lines so that the results would be more directly applicable to breeding than those from a diversity panel. The population was genotyped with 71,710 SNPs using genotyping-by-sequencing (GBS), and GWAS performed with the explicit goal of expediting selection in the breeding program. Using this breeding panel we identified 52 QTL for 11 agronomic traits, including large effect QTLs for flowering time and grain length/grain width/grain-length-breadth ratio. We also identified haplotypes that can be used to select plants in our population for short stature (plant height), early flowering time, and high yield, and thus demonstrate the utility of association mapping in breeding populations for informing breeding decisions. We conclude by exploring how the newly identified significant SNPs and insights into the genetic architecture of these quantitative traits can be leveraged to build genomic-assisted selection models.     

Evolution of Cooperation Patterns in Psoriasis Research: Co-Authorship Network Analysis of Papers in Medline (1942–2013)

Background

Although researchers have worked in collaboration since the origins of modern science and the publication of the first scientific journals in the eighteenth century, this phenomenon has acquired exceptional importance in the last several decades. Since the mid-twentieth century, new knowledge has been generated from within an ever-growing network of investigators, working cooperatively in research groups across countries and institutions. Cooperation is a crucial determinant of academic success.

Objective

The aim of the present paper is to analyze the evolution of scientific collaboration at the micro level, with regard to the scientific production generated on psoriasis research.

Methods

A bibliographic search in the Medline database containing the MeSH terms “psoriasis” or “psoriatic arthritis” was carried out. The search results were limited to articles, reviews and letters. After identifying the co-authorships of documents on psoriasis indexed in the Medline database (1942–2013), various bibliometric indicators were obtained, including the average number of authors per document and degree of multi-authorship over time. In addition, we performed a network analysis to study the evolution of certain features of the co-authorship network as a whole: average degree, size of the largest component, clustering coefficient, density and average distance. We also analyzed the evolution of the giant component to characterize the changing research patterns in the field, and we calculated social network indicators for the nodes, namely betweenness and closeness.

Results

The main active research clusters in the area were identified, along with their authors of reference. Our analysis of 28,670 documents sheds light on different aspects related to the evolution of scientific collaboration in the field, including the progressive increase in the mean number of co-authors (which stood at 5.17 in the 2004–2013 decade), and the rise in multi-authored papers signed by many different authors (in the same decade, 25.77% of the documents had between 6 and 9 co-authors, and 10.28% had 10 or more). With regard to the network indicators, the average degree gradually increased up to 10.97 in the study period. The percentage of authors pertaining to the largest component also rose to 73.02% of the authors. The clustering coefficient, on the other hand, remained stable throughout the entire 70-year period, with values hovering around 0.9. Finally, the average distance peaked in the decades 1974–1983 (8.29) and 1984–2003 (8.12) then fell over the next two decades, down to 5.25 in 2004–2013. The construction of the co-authorship network (threshold of collaboration ≥ 10 co-authored works) revealed a giant component of 161 researchers, containing 6 highly cohesive sub-components.

Conclusions

Our study reveals the existence of a growing research community in which collaboration is increasingly important. We can highlight an essential feature associated with scientific collaboration: multi-authored papers, with growing numbers of collaborators contributing to them, are becoming more and more common, therefore the formation of research groups of increasing depth (specialization) and breadth (multidisciplinarity) is now a cornerstone of research success.