CAPITAL LETTERS: Fragile X Gene (FMR1) Expression in the Developing Rat
Cerebellar Cortex
We examined the expression pattern of the Fragile X Mental Retardation
Gene (FMR1) in the rat cerebellum using a radiolabelled cDNA oligonucleotide. Four
distinct expression patterns were evident in parasagittal
cerbellar sections across the ages of of 5, 10, 15 and 20 days. At 5
days, autoradiograms revealed gene expression that was strongest in the most
superficial layers of the cerebellum. Corresponding Nissl stains confirm
this to be the external granule layer (EGL), with immunoreactivity also present in the
Internal Granule Layer
(IGL). The Molecular Layer (ML) can not be distinguished by differential laminary
FMR1
expression at this stage. At 10 days, FMR1 mRNA expression remains high in the EGL
and IGL and the ML could now be distinguished due to the absence
of FMRP expression. At Day 15, the EGL and IGL were still visible,
although the EGL had become thinner and the ML has had grown significantly
wider (again made apparent by the lack of expression). At Day 20, the EGL was no
longer visible, the ML was greatly expanded and the high level of expression was limited
to the thick IGL layer. This pattern suggests the FMR1 expression is
primarily restricted to cerebellar layers that contain granule cells and
Purkinje cells during development. The expression
pattern seen corresponds to the migration of granule cells from the EGL,
past the pyramidal cells into the IGL during development.
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NEUROGENESIS IN MOTOR CORTICAL REGIONS OF ADULT MACAQUE MONKEYS
J. L. Boklewski5, R. Galvez,1,5* H. Lange, J, Bytheway, K. McCormick, N.I. Williams, J.L. Cameron, and
W.T. Greenough.1,2,3,4,5 Beckman Institutue 1Neuroscience Program, Depts. 2Psychology, 3Psychiatry, 4Cell
& Structural Biology, 1Neuroscience Program 5Beckman Inst., Univ. of IL, Urbana, IL 61801, Penn. St.
Univ. and University of Pittsburgh
In response to opportunities for exercise and learning, rats exhibit increased neuron number,
vascularization and and gliogenesis, as well as increased neurotrophic factor expression, in various brain
regions. This study asked whether similar neurogenesis occurs in primate brain. Adult female monkeys
were trained to run on motorized treadmills for one hour a day, 5 days a week, for 20 weeks (n=16; average
exercise level=1.9±0.4 miles/day). A control group sat on treadmills for the same duration (n=8). Starting
at week 5, monkeys underwent cognitive testing using the Wisconsin General Testing Apparatus (WGTA;
see adjacent poster). Animals were injected subcutaneously once weekly with 50 mg/kg BrdU to label
newly-generated cells. At the end of the 20 week period (or after a delay of ? additional weeks for half of
the exercise subjects), animals were anesthetized and intracardially perfused with …. A block containing
areas of primary motor and somatosensory cortex was cryosectioned at 40 m and immunostained for
BrdU and NeuN. Sections were examined using fluorescence detection in a Leica SP2 confocal laser
microscope. BrdU labelling of cells was common. Most BrdU-labeled cells were not co-labelled for NeuN,
suggesting that the bulk of newly-generated cells were not neurons. A small number of cells, however,
exhibited co-labeling for BrdU and NeuN. Assuming that the relatively high levels of labelling observed
cannot be attributed to DNA repair, this result suggests that new neurons had formed in the motor cortex
during the period of labeling. Ongoing studies are determining whether exercise specifically affects the
genesis of neurons, as has been elucidated in rodents.