New Mouse Lines for the Analysis of Neuronal Morphology Using CreER(T)/loxP-Directed Sparse Labeling

BACKGROUND: Pharmacologic control of Cre-mediated recombination using tamoxifen-dependent activation of a Cre-estrogen receptor ligand binding domain fusion protein [CreER(T)] is widely used to modify and/or visualize cells in the mouse. METHODS AND FINDINGS: We describe here two new mouse lines, constructed by gene targeting to the Rosa26 locus to facilitate Cre-mediated cell modification. These lines should prove particularly useful in the context of sparse labeling experiments. The R26rtTACreER line provides ubiquitous expression of CreER under transcriptional control by the tetracycline reverse transactivator (rtTA); dual control by doxycycline and tamoxifen provides an extended dynamic range of Cre-mediated recombination activity. The R26IAP line provides high efficiency Cre-mediated activation of human placental alkaline phosphatase (hPLAP), complementing the widely used, but low efficiency, Z/AP line. By crossing with mouse lines that direct cell-type specific CreER expression, the R26IAP line has been used to produce atlases of labeled cholinergic and catecholaminergic neurons in the mouse brain. The R26IAP line has also been used to visualize the full morphologies of retinal dopaminergic amacrine cells, among the largest neurons in the mammalian retina. CONCLUSIONS: The two new mouse lines described here expand the repertoire of genetically engineered mice available for controlled in vivo recombination and cell labeling using the Cre-lox system

Dopamine receptor localization in the mammalian retina.

After a short history of dopamine receptor discovery in the retina and a survey on dopamine receptor types and subtypes, the distribution of dopamine receptors in the retinal cells is described and correlated with their possible role in cell and retinal physiology. All the retinal cells probably bear dopamine receptors. For example, the recently discovered D1B receptor has a possible role in modulating phagocytosis by the pigment epithelium and a D4 receptor is likely to be involved in the inhibition of melatonin synthesis in photoreceptors. Dopamine uncouples horizontal and amacrine cell-gap junctions through D1-like receptors. Dopamine modulates the release of other transmitters by subpopulations of amacrine cells, including that of dopamine through a D2 autoreceptor. Ganglion cells express dopamine receptors, the role of which is still uncertain. M?r cells also are affected by dopamine. A puzzling action of dopamine is observed in the ciliary retina, in which D1- and D2-like receptors are likely to be involved in the cyclic regulation of intraocular pressure. Most of the dopaminergic actions appear to be extrasynaptic and the signaling pathways remain uncertain. Further studies are needed to better understand the multiple actions of dopamine in the retina, especially those that implicate rhythmic regulations

Immunohistochemical localization of GABA-containing neurons during postnatal development of the rat retina.

The localization of neurons containing gamma-amino-butyric acid (GABA)-immunoreactivity has been studied in the rat retina during postnatal development. Two populations of GABA-positive cells were observed. The first was located in the inner layers of the retina, with the number of cells and their immunoreactivity increasing during development until adulthood. Previous studies in adult rat enabled identification of these cells as a subpopulation of amacrine cells. The second was located in the outer layers of the retina. These cells displayed a transient GABA labelling, with no immunoreactivity detectable after postnatal day 15. Their localization and morphology corresponded to calbindin D-27kDa-positive horizontal cells. It was concluded that the transient GABA-positive cells were horizontal cells.Journal ArticleResearch Support, Non-U.S. Gov'tinfo:eu-repo/semantics/publishe

Recoverin and hippocalcin distribution in the lamprey (Lampreta fluviatilis) retina.

Recoverin is a calcium-sensing protein which is involved in the transduction of light in vertebrate photoreceptors. It is also detected in other retina cell types in which its function is not yet elucidated, and is an autoantigen in a cancer-associated degenerative disease of the retina. Recently, hippocalcin, an homologous protein of recoverin, belonging to the same family of fatty acylated EF-hand calcium binding proteins was described in mammals. The immunohistochemical studies presented in this paper demonstrate, that, in the retina of the lamprey, an Agnathan considered the living ancestor of actual jawed vertebrates, recoverin was present in all photoreceptors and, to a lesser extent in subpopulations of amacrine and ganglion cells whereas hippocalcin was detected in numerous amacrine and ganglion cells and in the inner segments of long photoreceptors. The existence of these calcium-binding proteins shows that they have a high degree of conservation during evolution. Their presence in the same cells that in jawed vertebrates (photoreceptors and ganglion cells for recoverin; amacrine and ganglion cells for hippocalcin) suggests that some retinal functions are well conserved but because they were also found in different cell types than in other species (amacrine for recoverin; photoreceptors for hippocalcin), they may have functions more specific to the lamprey retina.Comparative StudyJournal Articleinfo:eu-repo/semantics/publishe

Changes in retinal dopaminergic cells and dopamine rhythmic metabolism during the development of a glaucoma-like disorder in quails

54 refs.International audienc

Changes in retinal dopaminergic cells and dopamine rhythmic metabolism during the development of a glaucoma-like disorder in quails

54 refs.International audienc

Immunohistochemical localization of calbindin-D28K and calretinin in the lamprey retina.

Calbindin-D28K and calretinin are homologous cytosolic calcium binding proteins localized in many retinal neurons from different species. In this report, location of cells immunoreactive to both proteins was investigated in the retina of the lamprey, Lampetra fluviatilis. This organism constitutes one of the older representative vertebrates and possesses a peculiar organization, probably unique: two-thirds of the ganglion cells are in the classical amacrine cell layer and the nerve fiber layer is located in the scleral part of the inner plexiform layer. Calbindin-like immunoreactivity was demonstrated in large bipolar cells and in cell bodies located in the inner retina. Although the distinction between labelled ganglion cells and labelled amacrine cells was rendered difficult, we hypothesized that the majority of calbindin-immunoreactive cells observed in the inner retina are ganglion cells, because of the high number of labelled fibers in the nerve fiber layer. Calretinin-like immunoreactivity was detected in both large and small bipolar cells, and also in cells located in the inner retina. Since few calretinin-immunoreactive fibers were observed in the nerve fiber layer, we assume that the latter category of cells are amacrine cells. Horizontal cells were both negative for calbindin and calretin-like immunoreactivities. Calbindin and calretinin, which are present in cones from many species, could not be detected in the photoreceptor layer favouring the rod-dominated lamprey retina. Although their distribution differs from those observed in most vertebrates, the present results indicate the good conservation of both calcium binding proteins in the retina during the vertebrate evolution.Journal ArticleResearch Support, Non-U.S. Gov'tFLWNASCOPUS: ar.jinfo:eu-repo/semantics/publishe