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B Oppermann

Publications and source records attributed to B Oppermann.

4 recordsLinked to original sources
PubMed2001

Quantitation of PAX6 and PAX6(5a) transcript levels in adult human lens, cornea, and monkey retina.

PURPOSE: PAX6 is a critical regulator of the developing lens, other ocular tissues, central nervous system, and pancreas. There are two alternatively spliced forms of the protein, PAX6 and PAX6(5a), that may have different regulatory functions. This study was designed to determine the amounts of PAX6 and PAX6(5a) transcripts present in adult human lens epithelium and fibers, human cornea and monkey retina. METHODS: PAX6 and PAX6(5a) transcript levels were monitored in microdissected lens epithelia, lens fibers, whole lens, cornea, and retina by competitive RT-PCR. The levels of TBP/TFIID were examined in adult human lens epithelium and fibers as control. RESULTS: PAX6 and PAX6(5a) were expressed at equal levels in lens epithelium and fibers. Ninety-five times more PAX6 transcripts were detected in the epithelial cells than in the fibers. Adult human cornea and monkey retina expressed less PAX6/PAX6(5a) than lens epithelium but more than lens fibers. Correspondingly, 40 fold higher levels of TBP transcripts were detected in lens epithelium than fibers, suggesting reduced overall expression of transcription factors in the adult lens fibers. CONCLUSIONS: The presence of PAX6 and PAX6(5a) messages and proteins in adult lens epithelium suggest functions for both forms of PAX6 in the growth and maintenance of the adult human lens. The reduced levels of both forms of PAX6 in the lens fibers suggest down regulation of this gene during differentiation of epithelia into fibers. The lower level of TBP expression in lens fibers also suggests reduced transcriptional competence of adult lens fibers.

Animals↗
PubMed2001

Identification and spatial analysis of metallothioneins expressed by the adult human lens.

PURPOSE: Metallothioneins (MTs) are a large family of proteins involved in multiple protective pathways including binding of toxic metals, free radical scavenging, and oxidative stress. Increased expression of the MT IIA gene in age-related cataractous relative to normal human lenses, suggesting a role for MTs in the maintenance of lens transparency, has previously been detected. The MT family consists of many closely related isoforms grouped into four classes (I-IV). As a first step toward defining the function of MTs in the lens, the range and expression patterns of those MT isoforms expressed by the adult human lens were established. METHODS: Normal human lenses were microdissected into epithelia and fiber cells. Primers specific for individual MT isoforms were designed. MT transcripts were monitored in whole lenses, epithelia, and fibers by RT-PCR and confirmed to be authentic by sequencing. MT protein levels were evaluated by immunoblotting and by immunostaining. RESULTS: Transcripts encoding MT classes I and II but not III or IV were detected in adult human lenses. In addition to MT IIA, five other MT transcripts were identified including IE, IF, IG, IH, and IL. MT IIA was detected almost exclusively in the lens epithelium, whereas the class I isoforms were detected at high levels in both lens epithelia and fibers. MT protein was detected almost exclusively in the lens epithelium. CONCLUSIONS: The present report establishes the spectrum of MTs expressed by the adult human lens, defines their spatial expression patterns in lens epithelia and fibers, and demonstrates that MT protein is abundantly present in the lens epithelium.

Adolescent↗
PubMed1979

Conditioned audio-visual targeting reflexes in split brain cats.

A conditioned audio-visual targeting reflex was elaborated in 12 freely moving cats. The cats had to localize the loudspeaker emitting by a tone of 1600 Hz, of 500 ms duration and 80 dB intensity. Each time one of the eight loudspeakers placed in front and behind the cat was activated and the targeting reaction rewarded by food. Normal cats attained the 80 percent criterion for the front and rear loudspeakers in 20 and 30 sessions, respectively. The influence of the transection of the corpus callosum on acquisition and retention of the targeting reaction was investigated. The split brain animals with pre-operative experience in the situation did not show any retention, but relearned the targeting of the frontal sources in 20 sessions. No relearning of the posterior sound sources was observed. The animals that had only post-operative training did not reach 80 percent of correct responses in 50 sessions. Corpus callosum transection influences the integration of the targeting reaction in different ways, depending on the position of the sound source and on pre-operative training.

Animals↗