The epithelium of the adult prostate contains 3 distinct cell types: basal, luminal, and neuroendocrine. Tissue-regenerative activity has been identified predominantly from the basal cells, isolated by expression of CD49f and stem cell antigen-1 (Sca-1). An important question for the field is whether all basal cells have stem cell characteristics. Prostate-specific microarray databases were interrogated to find candidate surface antigens that could subfractionate the basal cell population. Tumor-associated calcium signal transducer 2 (TACSTD2/Trop2/M1S1/GA733-1) was identified because it was enriched after castration, in prostate sphere cells and in the basal fraction. In the murine prostate, Trop2 shows progenitor characteristics such as localization to the region of the gland proximal to the urethra and enrichment for sphere-forming and colony-forming cells. Trop2 subfractionates the basal cells into 2 populations, both of which express characteristic basal cell markers by quantitative PCR. However, only the basal cells expressing high levels of Trop2 were able to efficiently form spheres in vitro. In the human prostate, where Sca-1 is not expressed, sphere-forming progenitor cells were also isolated based on high expression of Trop2 and CD49f. Trop2-expressing murine basal cells could regenerate prostatic tubules in vivo, whereas the remaining basal cells had minimal activity. Evidence was found for basal, luminal, and neuroendocrine cells in prostatic tubules regenerated from Trop2 hi basal cells. In summary, functionally distinct populations of cells exist within the prostate basal compartment and an epithelial progenitor can give rise to neuroendocrine cells in vivo.neuroendocrine ͉ progenitor ͉ sphere assay
We demonstrate an efficient D-A-π-A sensitizer with a benzothiadiazole-cyclopentadithiophene [corrected] moiety as the spacer in a triphenylamine organic dye for dye-sensitized solar cells. The dye has a broad visible light absorption range up to 800 nm. A power conversion efficiency >9% has been achieved using a [Co(bpy)3](2+/3+)-based electrolyte.
Combining the Mars Atmosphere and Volatile Evolution measurements of neutral atmospheric density, solar EUV/X-ray flux, and differential photoelectron intensity made during 240 nominal orbits, we calculate the ionization efficiency, defined as the ratio of the secondary (photoelectron impact) ionization rate to the primary (photon impact) ionization rate, in the dayside Martian upper atmosphere under a range of solar illumination conditions. Both the CO 2 and O ionization efficiencies tend to be constant from 160km up to 250km, with respective median values of 0.19±0.03 and 0.27±0.04. These values are useful for fast calculation of the ionization rate in the dayside Martian upper atmosphere, without the need to construct photoelectron transport models. No substantial diurnal and solar cycle variations can be identified, except for a marginal trend of reduced ionization efficiency approaching the terminator. These observations are favorably interpreted by a simple scenario with ionization efficiencies, as a first approximation, determined by a comparison between relevant cross sections. Our analysis further reveals a connection between regions with strong crustal magnetic fields and regions with high ionization efficiencies, which are likely indicative of more efficient vertical transport of photoelectrons near magnetic anomalies.
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