Netrin-1-like Peptides Are Secreted by Tetrahymena thermophila

Netrin-1 is a peptide signaling molecule that has many roles in vertebrates. In the ciliated protozoan, Tetrahymena thermophila, netrin-1 acts as a chemorepellent, causing cells to exhibit a characteristic avoidance behavior. We have previously shown that netrin-1 avoidance by T. thermophila is inhibited by genistein, which is a broad spectrum tyrosine kinase inhibitor. One question we wished to answer in our current study was, “Is genistein specifically acting upon tyrosine kinases in order to inhibit netrin avoidance in Tetrahymena?” In order to answer this question, we used the phytoestrogen, diadzein, as a negative control for genistein inhibition. Diadzein had no effect on avoidance, suggesting that genistein inhibition is specific. In order to gain more information about the nature of the kinases involved in netrin-1 signaling, we tested several other kinase inhibitors, including a src inhibitor, a focal adhesion kinase inhibitor, and a Rho kinase inhibitor. Each of these kinases has been implicated in netrin-1 signaling in some vertebrate cell types. However, none of these inhibitors affected Tetrahymena avoidance to netrin-1. Finally, we wished to answer the question, “Is netrin-1 actually serving an autocrine signaling role in Tetrahymena, or is the peptide merely serving as an agonist for another receptor?” In order to answer this question, we prepared a whole cell extract of Tetrahymena using 0.1% SDS. We also washed Tetrahymena in our behavioral buffer and allowed them to sit in that buffer for 24 hours. The Tetrahymena were centrifuged out of the buffer, and the supernatant, containing the proteins which the Tetrahymena had secreted, was kept for ELISA assay. An ELISA, using a polyclonal anti netrin-1 antibody, was run on the whole cell extract and the secreted proteins against a netrin-1 standard curve. Both the secreted proteins and the whole cell extract tested positive for netrin-1 in the ELISA. Further experimentation will allow us to determine the nature of these netrin-like peptides

Netrin-1 Peptide Is a Chemorepellent in \u3cem\u3eTetrahymena thermophila\u3c/em\u3e

Netrin-1 is a highly conserved, pleiotropic signaling molecule that can serve as a neuronal chemorepellent during vertebrate development. In vertebrates, chemorepellent signaling is mediated through the tyrosine kinase, src-1, and the tyrosine phosphatase, shp-2. Tetrahymena thermophila has been used as a model system for chemorepellent signaling because its avoidance response is easily characterized under a light microscope. Our experiments showed that netrin-1 peptide is a chemorepellent in T. thermophila at micromolar concentrations. T. thermophila adapts to netrin-1 over a time course of about 10 minutes. Netrin-adapted cells still avoid GTP, PACAP-38, and nociceptin, suggesting that netrin does not use the same signaling machinery as any of these other repellents. Avoidance of netrin-1 peptide was effectively eliminated by the addition of the tyrosine kinase inhibitor, genistein, to the assay buffer; however, immunostaining using an anti-phosphotyrosine antibody showed similar fluorescence levels in control and netrin-1 exposed cells, suggesting that tyrosine phosphorylation i s not required for signaling to occur. In addition, ELISA indicates that a netrin-like peptide is present in both whole cell extract and secreted protein obtained from Tetrahymena thermophila. Further study will be required in order to fully elucidate the signaling mechanism of netrin-1 peptide in this organism

Teacher training for political science PhD students in Europe: determinants of a tool for enhanced teaching in higher education

In this paper we examine the state of teacher training for political science PhD candidates in the European Union and make a comparison with the situation in the United States. We investigate the determinants of supply and demand of teacher training. On the supply side, we suggest that research orientation and quality assurance are factors that might enhance institutional willingness to provide training. On the demand side, we examine the influence of gender, career plans, year of study, and career status on student motivation to undergo teacher training. We find that about half of EU institutions offering PhD programs also provide some form of teacher training; this closely follows American trends. We also uncover that while research orientation has a significant positive effect on the willingness of universities to provide training in pedagogy, quality assurance does not. Of the four factors we put forward as potential influences on student demand for teacher training, only future plans have a significant effect. We argue that similarities in the situation of teacher training in the United States and the European Union make transatlantic dialogue in graduate education worthwhile. Moreover, the positive impact of teacher training on the quality of teaching and learning as well as the positive valuation of training by more than two-thirds of PhD students in our sample makes us conclude that teacher training should be more widely available

Mouse Chromosome 11

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/46996/1/335_2004_Article_BF00648429.pd

Cabo San Lucas

https://digitalcommons.cedarville.edu/library_photo_contest_fall_2018/1001/thumbnail.jp

Globalization and the right to free association and collective bargaining: an empirical analysis

Economies that are more open to trade and foreign direct investment face greater competitive pressure than closed ones. Globalization critics are concerned that this pressure induces countries to lower labor standards in order to remain competitive and retain or attract foreign investment. Defenders of globalization counter that countries that are more closely integrated into global markets are likely to have higher rather than lower standards. This article tests the effect of globalization on a specific labor right, which forms part of what are commonly regarded as core or fundamental labor standards. Employing a new measure of free association and collective bargaining rights, we find that countries that are more open to trade have fewer rights violations than more closed ones. This effect holds in a global sample as well as in a developing country sub-sample and holds also when potential feedback effects are controlled via instrumental variable regression. The extent of an economy’s ‘penetration’ by foreign direct investment has no statistically significant impact. Globalization might not be beneficial for outcome-related labor standards, but it is likely to promote the process-related standard of a right to free association and collective bargaining