Amanda Charlesworth, PhD
I am interested in the molecular changes that drive developmental
processes. In the CTN I am investigating the molecular mechanisms
that control the developmental decrease in REM sleep. Newborn
mammals spend a large proportion of time in REM sleep and by
adulthood, this has substantially decreased. The reticular
activating system is thought to regulate REM sleep but it is not
known how. We have been investigating the hypothesis that neurons in
the reticular activating system are electrically coupled via gap
junctions. We have found that the neuronal gap junction protein,
connexin-36, is expressed in the SubCoeruleus nucleus of the
reticular activating system (see figure below). Additionally,
connexin-36 levels decrease during development, a decrease that
mirrors the decrease in REM sleep. The mechanisms behind the
decrease in expression of connexin-36 are being investigated.
36 expression and protein levels over age. A.
Ratio of Cx 36 mRNA vs each of
three housekeeping genes, Enolase (dark gray), Hprt (light gray) and
Gapdh (black), which did not differ from each other in developmental
expression. Mean and SE of 3 mesopontine tegmenti of 7 day, 17 day
and adult rats. Note the gradual decrease in Cx 36 expression in
development but with significant levels present in adults. B.
Cx 36 protein levels in representative mesopontine tegmenti of 7
day, 17 day and adult rats. Levels decreased gradually from 7 to 17
days to adult, such that longer exposures (Connexin-36 hi-exp) were
required to visualize protein levels in adults. Blot was reprobed
for actin protein levels to verify equal loading. C.
Photomicrograph of 400 um sagittal slice through a 30 day medial
brainstem showing punched region (1 mm diameter) ventral to the
Locus Coeruleus (the punch was centered anterior to the 7th nerve
but included the nerve as it descended) in the SubC region. D.
Cx 36 protein levels were normalized to Actin in slices
containing the SubC from rats from 4 litters aged 10 days and 30
days. Note the decrease in protein levels across the developmental
decrease in REM sleep. E. Cx 36 protein from these pooled
samples from 10 day and 30 rats normalized to Actin loading. Actin
protein levels are shown to verify equal loading.
Charlesworth, A., Welk, J. and MacNicol, A. M. (2000) The
temporal control of Wee1 mRNA translation during Xenopus oocyte
maturation is regulated by cytoplasmic polyadenylation elements within
the 3'-untranslated region. Dev Biol 227, 706-719.
Charlesworth, A., Ridge, J. A., King, L. A., MacNicol, M. C. and
MacNicol, A. M. (2002) A novel regulatory element determines the
timing of Mos mRNA translation during Xenopus oocyte maturation. Embo J
Charlesworth, A., Wilczynska, A., Thampi, P., Cox, L. L. and
Macnicol, A. M. (2006) Musashi regulates the temporal order of mRNA
translation during Xenopus oocyte maturation. Embo J 25, 2792-2801.
Heister, D. S., Hayar, A., Charlesworth, A., Yates, C., Zhou, Y.
H. and Garcia-Rill, E. (2007) Evidence for Electrical Coupling in
the SubCoeruleus (SubC) Nucleus. J Neurophysiol 97, 3142-3147.
Garcia-Rill, E., Heister, D. S., Ye, M., Charlesworth, A. and
Hayar, A. (2007) Electrical coupling: novel mechanism for sleep-wake
control. Sleep 30, 1405-1414.
Wang, Y. Y., Charlesworth, A., Byrd, S. M., Gregerson, R.,
MacNicol, M. C. and MacNicol, A. M. (2008) A novel mRNA 3'
untranslated region translational control sequence regulates Xenopus
Wee1 mRNA translation. Dev Biol 317, 454-466.
Yates, C., Charlesworth, A., Allen, S. R., Reese, N. B., Skinner,
R. D. and Garcia-Rill, E. (2008) The onset of hyperreflexia in the
rat following complete spinal cord transection. Spinal Cord
Yates, C. C., Charlesworth, A., Reese, N. B., Skinner, R. D. and
Garcia-Rill, E. (2008) The effects of passive exercise therapy
initiated prior to or after the development of hyperreflexia following
spinal transection. Exp Neurol 213, 405-409.
Pubmed Link to Dr. Charlesworth's publications