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The Drosophila Extradenticle (Exd) protein is a cofactor to homeotic proteins and has regulated nuclear localization. The Drosophila homothorax (hth) gene has been cloned. It is a homolog of the mouse Meis1 proto-oncogene that has a homeobox related to the exd homeobox. The Homothorax homeoprotein suppresses eye development in Drosophila. Hth acts upstream from exd and is required and adequate for Exd protein nuclear localization. It is likely hth works with exd to give parameters to the eye field and to prevent eye development that is not appropriate.

Abstract: The molecular mechanisms of development of mechanosensory hair cells have been tackled successfully due to in vivo studies in the zebrafish lateral line. The enhancer trap (ET) transgenic line, SqET4 was instrumental in these studies even despite a lack of a link of its GFP expression pattern to a particular gene(s). We mapped the Tol2 transposon insertion of the SqET4 transgenics onto Chr. 4 next to a gene encoding Atp2b1a (Pmca1) – one of the four PMCAs acting to export Ca2+ from a cell. atp2b1a expression recapitulates that of GFP during the development of mechanoreceptors of the inner ear and lateral line. atp2b1a expression correlates with the regeneration of these cells. Thus, SqET4 represents the Tg:atp2b1a-GFP line, which links Ca2+ metabolism and the differentiation of mechanoreceptors. The morpholino-mediated knockdown of atp2b1a blocks Ca2+ export and affects the division of hair cell progenitors, resulting in their accumulation. Under the control of a master gene of hair cells, Atoh1a, Atp2b1a functions during progenitor cell proliferation and hair cell differentiation. Given the similarity between the phenotypes of atp2b1a morphants and embryos treated with the pan-PMCA inhibitor 5(6)-carboxyeosin, Atp2b1a emerges as member of the Atp2b family responsible for Ca2+ export during the development of hair cells. [ABSTRACT FROM AUTHOR]

Provides information on a study that reported the identification of a Drosophila Pax gene, eye gone, which is required for eye development. Methodology of the study; Results and discussion on the study.

New tools and approaches of quantum optics offer a unique opportunity to generate light pulses carrying a precise number of photons. Accurate control over the light pulses helps to improve the characterization of photoinduced processes. Here, we study interaction of a specialized light source which provides flashes containing just one photon, with retinal rod cells of Xenopus laevis toads. We provide unambiguous proof of the single-photon sensitivity of rod cells without relying on the statistical modeling. We determine their quantum efficiencies without the use of any precalibrated detectors and obtain the value of (29 ± 4.7)%, Our approach provides the path for future studies and applications of quantum properties of light in phototransduction, vision, and photosynthesis. [ABSTRACT FROM AUTHOR]