View larger version (114K):
[in a new window]
|
Fig. 4. Cellular expression of Brn3a target genes in the CNS. The brain and retina
of E13.5 embryos were examined for alterations in Brn3a target genes
identified in the trigeminal ganglion. (A) Calretinin and Brn3a characterize
distinct populations of developing neurons in the E13.5 developing thalamus,
midbrain, and hindbrain, shown in sagittal section, and are not co-expressed
(inset). The diagonal line indicates the plane of section used in the midbrain
views (B,C,G,H,L). (B) Control midbrain, showing distinct expression of Brn3a
and calretinin. (C) Unchanged expression of calretinin in the Brn3a
knockout midbrain. (D,E) Control retina, showing calretinin and Brn3a
expression in overlapping populations of neurons. (F) Brn3a knockout
retina showing no apparent increase in calretinin immunoreactivity. (G,H)
Distinct patterns of somatostatin and Brn3a immunoreactivity in the midbrain,
which are not changed in the Brn3a knockout. (I,J) Retinal expression
of somatostatin, probably co-localized with Brn3a in a subset of ganglion
cells, although the axonal distribution of somatostatin immunoreactivity makes
precise cellular co-localization difficult to ascertain. (K) Retinal
expression of somatostatin also appears unaltered in the absence of Brn3a.
(L,M) Tyrosine hydroxylase and Brn3a identify entirely distinct populations of
developing neurons in the ventral tegmental area (VTA) and the tegmentum
(nuclei stained red), respectively. Scale bars: A, 400 µm; B,D,G, 100
µm; I, 100 µm; L, 200 µm; M, 50 µm.
|
CiteULike 
Complore 
Connotea 
Del.icio.us 
Digg 
Reddit 
Technorati 
Twitter What's this?
4,000 present
transcripts, including ESTs, in one of the two experiments comparing
Brn3a heterozygous and knockout trigeminal ganglia. Values for the
expression of the majority of transcripts fall along the central diagonal line
representing equal expression in the two genotypes. A few transcripts fall
outside the parallel lines indicating a greater than twofold change in
expression, and examples of some highly changed transcripts are indicated. (B)
To determine whether Brn3a heterozygosity results in intermediate
levels of target gene expression, two-way comparisons were made between
transcript levels in knockout versus wild-type, knockout versus heterozygous
and wild-type versus heterozygous ganglia for the 41 increased and 62
decreased transcripts from the U74Av2 array, Experiment 1. Expression levels
in wild type and heterozygotes showed a similar mean fold increase or decrease
when compared to those in the knockout. However, comparison of expression
levels in heterozygotes with those in wild type revealed no significant
difference (fold change 
