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Biomedical subjects

R BreMiller

Publications and source records attributed to R BreMiller.

6 recordsLinked to original sources

Use of a new fluorogenic phosphatase substrate in immunohistochemical applications.

We used the phosphatase substrate 2-(5'-chloro-2'-phosphoryloxyphenyl)-6- chloro-4-[3H]-quinazolinone, with standard alkaline phosphatase-mediated immunohistochemical techniques, to visualize a number of antibodies that bind to adult zebrafish retinal tissue. This compound, known as the ELF (enzyme-labeled-fluorescence) phosphatase substrate, produces a precipitate that fluoresces at approximately 500-580 nm (bright yellow-green). We show that the precipitated product from the ELF phosphatase substrate has a number of characteristics that make it superior to fluorescein-labeled secondary reagents. The staining produced with the ELF substrate is much more photostable than that produced by fluorescein-labeled secondary reagents, thus allowing time to examine, focus, and photograph the ELF-labeled tissue under high magnification. Moreover, the ELF precipitate exhibits a Stokes shift of greater than 100 nm, a characteristic that has enabled us to overcome the problem of distinguishing signal from background in this autofluorescent tissue. In addition, we show that the ELF product's large Stokes shift makes the ELF substrate ideal for multicolor applications.

Alkaline Phosphatase↗

Decreasing the cortical response to monocular deprivation need not decrease cell shrinkage in cat lateral geniculate nucleus.

Monocular deprivation (MD) of young kittens decreases the response of visual cortex cells to the deprived eye. In addition, it causes cell shrinkage in the layers of the lateral geniculate nucleus (LGN) innervated by the deprived eye. To determine whether the shrinkage of LGN cells is dependent upon changes in the response of cortical cells, we compared LGN cell shrinkage in three groups of MD animals. Two were controls; the third received lesions of fibers bringing norepinephrine and acetylcholine to the visual cortex. This procedure greatly attenuated the effect of MD on the visual cortex. The amount of LGN cell shrinkage did not differ among the three groups. We conclude that LGN shrinkage after MD does not require a dramatic loss of cortical cell responses to the deprived eye.

Acetylcholine↗

Larval and adult visual pigments of the zebrafish, Brachydanio rerio.

Photoreceptors of adult and larval zebrafish were assayed by microspectrophotometry to characterize their visual pigments, and to determine when the visual pigments first appear during development. Short single cone outer segments contained a pigment with a lambdamax near 417 nm. Long single cones and long members of double cone outer segments contained a pigment with a lambdamax near 480 nm. Short members of double cone outer segments contained a pigment with a lambdamax near 556 nm. Rod outer segments contained a rhodopsin with a lambdamax near 501 nm. All four visual pigment types found in adult photoreceptors were present in the earliest measurable larval photoreceptors.

Aging↗

Further evidence for latent learning in hippocampal-lesioned rats.

Rats with substantial dorsolateral lesions to the hippocampal formation showed significant latent learning of a complex spatial maze. Their overall maze performance, however, was characteristically impaired. Behavior during the pre-exposure phase of the experiment was useful in predicting test maze behavior. Three measures in particular had predictive value: entrances into the maze alley leading to the final choice point, behavior at that choice point, and goal box entries.

Animals↗