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We tested the effects of several growth factors on the proliferation and differentiation of cells in the teleost retina which typically become rod photoreceptors to understand their regulation. Using organotypic slice cultures of differentiated teleost fish retinal tissue, we found that insulin and insulin-like growth factor I (IGF-I) stimulate(More)
Development of the retina, like that of other tissues, occurs via an orderly sequence of cell division and differentiation, producing the functional retina. In teleost fish, however, cell division and differentiation in the retina continue throughout the life of the animal in two distinct ways. Stem cells in a circumferential germinal zone at the periphery(More)
To determine whether the number of cell divisions in the teleost retina exhibited a regular daily variation, we labeled dividing cells with an antibody to proliferating cell nuclear antigen. The number of dividing rod precursor cells in the outer nuclear layer of the retina were counted in retinas from the telost fish Haplochromis burtoni, sacrificed at 4-h(More)
Teleost fish retinas continue to add neurons throughout life, and evidence from in vitro experiments have implicated insulin-like growth factors (IGFs) in this process. To discover whether these factors are expressed in vivo, we have examined their expression in the cichlid fish, Haplochromis burtoni. Three lines of evidence show that IGFs are present in(More)
Teleost fish continue to grow throughout life, and their eyes enlarge correspondingly. Within the eye, the retina grows by stretching existing tissue and adding new cells. Cell addition occurs in two ways: First, all cell types except rod photoreceptors are added circumferentially at the edge of the eye where the retina meets the iris; second, rod(More)
To understand the cellular context of neuronal differentiation in the vertebrate retina, we analyzed the behavior of a class of progenitor cells in the outer nuclear layer of the teleost retina which divide throughout the animal's life and generate only rod photoreceptors. We present evidence that these progenitors reside adjacent to the outer limiting(More)
The authors analyzed the pattern of neurogenesis, the time frame of cell movement, and the cell cycle kinetics of a population of stem cells located in the outer nuclear layer in the retina of the adult teleost Haplochromis burtoni. These stem cells continue to give rise to new rod photoreceptors throughout life. The new rods move vitread after the last(More)
The serum- and glucocorticoid-dependent kinase SGK1 is regulated by alterations of cell volume, whereby cell shrinkage increases and cell swelling decreases the transcription, expression and activity of SGK1. The kinase is expressed in all human tissues studied including the brain. The present study was performed to localize the sites of SGK1 transcription(More)
The desire to extend product development success internationally and understand users in the countries in which a product will be marketed has extended user methods overseas. While the practice of international research has become common, approaches have been varied depending on the needs of the project as well as corporate constraints. Many corporate(More)
Understanding the size of clutches produced by only one parent may require a game-theoretic approach: clutch size may affect offspring fitness in terms of future competitive ability. If larger clutches generate smaller offspring and larger adults are more successful in acquiring and retaining resources, clutch size optima should be reduced when the(More)