#Beam breaks actimeter serial

f, Schematic representation of the conditional ophn1 knock-out allele before and after cre-mediated inversion. In c–e, error bars indicate SEM, and asterisks indicate statistical differences between means. Filopodia length was significantly longer for mutant neurons than for control (3.95 μm in wild type vs 4.54 in knock-out F = 7.5 p < 0.007). Insets show the mean filopodia length for the two genotypes. The line graphs show the cumulative probability distribution of filopodia lengths for ophn1 −/y (black) and ophn1 +/y (gray) neurons. e, Filopodia length cumulative distribution. The stubby spines remain unchanged, whereas filopodia and, to a lesser extent, mushroom-shaped spines are increased in ophn1 −/y neurons. d, Relative proportions of dendritic spines in ophn1 −/y (black) and ophn1 +/y (gray) neurons. All protrusions observed over 100 μm of primary dendrites were counted, and data were obtained from three independent culture experiments (total number of protrusions, n = 888 ophn1 +/y and 1088 ophn1 −/y). We discriminated between immature filiform-shaped protrusions (filopodia), stubby spines, and mushroom-shaped spines. c, Densities of dendritic protrusions in ophn1 −/y (black) and ophn1 +/y (gray) neurons. Note the existence of numerous long and thin filopodia with mushroom-shaped spines in the ophn1 −/y neuron along the primary dendritic segment. Hippocampal neurons were stained with fluorescent dye-conjugated phalloidin, which labels actin-rich dendritic protrusions. a, b, Dendritic protrusions in ophn1 +/y ( a) and ophn1 −/y ( b) neurons at 21 div. Loss of ophn1 leads to an increase in dendritic protrusions during in vitro differentiation. There is no significant difference between genotypes for both variables. The right panel shows the corresponding neuronal densities in the pyramidal cell layer. The left panel of the histogram represents the excitatory synapse densities at 200 μm from the pyramidal layer in the stratum radiatum. d, Quantification of excitatory synapses and neuronal densities in ophn1 +/y and ophn1 −/y CA1 hippocampus. Asterisks indicate statistical differences between means. Analyses at 200 μm also showed a 30% reduction in dendritic spine densities (data not shown). c, Quantification of dendritic spine densities in apical dendrites from ophn1 +/y and ophn1 −/y CA1 neurons at 100 μm from the pyramidale cell layer. Note the reduction in spine density in ophn1 −/y neurons. Insets show a magnification of 20 μm dendritic segment arboring spines. a, b, Golgi staining of CA1 pyramidal neurons in ophn1 +/y and ophn1 −/y showing overall normal dendritic tree in ophn1 mutants.

Reduced apical spine density and basal spine length in ophn1 −/y CA1 hippocampal neurons. Ophn1 −/y shows no disruption of lamination in the hippocampus ( h) and no defect in the cerebellar foliation ( g) but presents some enlargement of lateral ventricles. Cresyl violet staining of sagittal cryosections of the ophn1 −/y and ophn1 +/y shows no detectable abnormalities in the histology of the cerebellum ( e, g) and hippocampus ( f, h). e–h, Normal cerebellar and hippocampal histology in ophn1 −/y. Note the similar appearance of the aqueduct of Sylvius and the fourth ventricle in the caudal sections, ruling out the possibility of a primary obstructive origin of the dilatation. The ventricle enlargement, apparent from rostral to caudal parts of the forebrain, is associated with thinning of the cerebral cortex.

#Beam breaks actimeter serial

Serial rostral to caudal coronal sections, stained with cresyl violet, from brains at 8 months are shown, with each pair of sections representing approximately the same coronal plane. c, d, Ophn1 −/y mice ( d) showed ventricle enlargement compared with ophn1 +/y mice ( c). Such a severe phenotype was found in 10% of ophn1 −/y mice ( b) and never in ophn1 +/y mice ( a) ( n = 20).

The resulting compression led to deformation of the skull and thinner cerebral cortex being almost transparent. a, b, In the most severe cases, ventricle enlargement led to the formation of hydrocephalus. Ophn1 −/y mice develop ventricle enlargement but not cerebellar hypoplasia.