No abstract

Diatoms have long been known to be photosensitive, altering the direction of their movement in response to changes in ambient light conditions detected at the tips of the cells. In order to better understand the light conditions responsible for triggering positive photophobic (out-of-light) and negative photophobic (into-light) responses of diatoms, cells from three species of diatoms, Craticula cuspidata (Kützing) D.G. Mann, Stauroneis phoenicenteron (Nitzsch) Ehrenberg, and Pinnularia viridis (Nitzsch) Ehrenberg, were irradiated at their leading or trailing ends during cell movement. The response times for direction changes when cells were irradiated at various irradiance levels and wavelengths were measured to determine the quality of light responsible for eliciting cell direction changes in each of the three species. All three species displayed strong out-of-light responses at the highest irradiances measured. Craticula cuspidata cells displayed negative photophobic sensitivity (into-light) responses in moderate level blue light, while S. phoenicenteron cells showed into-light responses with low-level red light. Pinnularia viridis cells showed less responsiveness to blue and green light than the other two species, and almost no sensitivity to red light. By re-irradiating cells a second time after a previous leading or trailing end irradiation, we observed a 2-3 fold (leading) or 3-8 fold (trailing) motility repression, caused by the initial light exposures, which lasted for approximately 30-60 sec. Irradiating the cells multiple times, upon each direction change, indicated some degree of habituation to irradiation over time. Multiple consecutive irradiations of the trailing end of diatoms resulted in strong repression of any direction change, with cells continuing to move in the same direction for up to 20 min; this repression became reduced as the interval time between trailing-end irradiations increased. These results suggest that diatoms display species-specific physiological responses to light irradiations that may help them to appropriately respond to ambient light conditions, and better organize and succeed within larger algal or multi-species diatom assemblages.

Wnt family proteins and β-catenin are critical for the regulation of many developmental and oncogenic processes. Wnts are secreted protein ligands which signal using a canonical pathway, and involve the transcriptional co-activator β-catenin or non-canonical pathways that are independent of β-catenin. Bone metastasis is unfortunately a common occurrence in prostate cancer and can be conceptualized as a series of related steps or processes, most of which are regulated by Wnt ligands and/or β-catenin. At the primary tumor site, cancer cells often take on mesenchymal properties, termed epithelial mesenchymal transition (EMT), which are regulated in part by the Wnt receptor FZD4. Then, Wnt signaling, especially Wnt5A, is of importance as the cells circulate in the blood stream. Upon arriving in the bones, cancer cells migrate and take on stem-like or tumorigenic properties, as aided through Wnt or β-catenin signaling involving CHD11, CD24, and Wnt5A. Additionally, cancer cells can become dormant and evade therapy, in part due to regulation by Wnt5A. In the bones, E-selectin can aid in the reversal of EMT, a process termed mesenchymal epithelial transition (MET), as a part of metastatic tumorigenesis. Once bone tumors are established, Wnt/β-catenin signaling is involved in the suppression of osteoblast function largely through DKK1.

No abstract

Analysts are selective about which forecasts they update and, thus, convey information about current quarter earnings even when not revising the current quarter earnings (CQE) forecast. We find that (1) textual statements, (2) share price target revisions, and (3) future quarter earnings forecast revisions all predict error in the CQE forecast. We document several reasons analysts sometimes omit information from the CQE forecast: to facilitate beatable forecasts by suppressing positive news from the CQE forecast, to herd toward the consensus, and to avoid small forecast revisions. We also show that omitting information from CQE forecasts leads to lower forecast dispersion and predictable returns at the earnings announcement.