The Syk Kinase SmTK4 of Schistosoma mansoni Is Involved in the Regulation of Spermatogenesis and Oogenesis

The signal transduction protein SmTK4 from Schistosoma mansoni belongs to the family of Syk kinases. In vertebrates, Syk kinases are known to play specialized roles in signaling pathways in cells of the hematopoietic system. Although Syk kinases were identified in some invertebrates, their role in this group of animals has not yet been elucidated. Since SmTK4 is the first Syk kinase from a parasitic helminth, shown to be predominantly expressed in the testes and ovary of adult worms, we investigated its function. To unravel signaling cascades in which SmTK4 is involved, yeast two-/three-hybrid library screenings were performed with either the tandem SH2-domain, or with the linker region including the tyrosine kinase domain of SmTK4. Besides the Src kinase SmTK3 we identified a new Src kinase (SmTK6) acting upstream of SmTK4 and a MAPK-activating protein, as well as mapmodulin acting downstream. Their identities and colocalization studies pointed to a role of SmTK4 in a signaling cascade regulating the proliferation and/or differentiation of cells in the gonads of schistosomes. To confirm this decisive role we performed biochemical and molecular approaches to knock down SmTK4 combined with a novel protocol for confocal laser scanning microscopy for morphological analyses. Using the Syk kinase-specific inhibitor Piceatannol or by RNAi treatment of adult schistosomes in vitro, corresponding phenotypes were detected in the testes and ovary. In the Xenopus oocyte system it was finally confirmed that Piceatannol suppressed the activity of the catalytic kinase domain of SmTK4. Our findings demonstrate a pivotal role of SmTK4 in gametogenesis, a new function for Syk kinases in eukaryotes

Journalists' development journalism role perceptions

Development journalism remains an important concept in the journalism studies literature, but it has, at the same time, suffered from a lack of empirical research. Drawing on a survey of 2598 journalists from eight South Asian, Southeast Asian, and sub-Saharan African countries, which was conducted as part of the Worlds of Journalism Study, this study assesses the importance journalists ascribe to three key development journalism roles—social intervention, national development, and educating people. It also compares these perceptions across the countries, between government- and privately owned news media in these countries, and between these countries and 19 Worlds of Journalism Study countries in Western Europe and North America, which profess to adhere to an objective and democratic press function. Findings suggest that journalists from the eight countries, across government- and privately owned media, considered development journalism important, and detached, adversarial journalism as less important. Their rating of the latter roles differed considerably from those of journalists from the 19 comparison countries. Results suggest that journalists were more likely socialized into their roles rather than being forced into the same by the heavy hand of government