Phenotypes associated with this allele

• Allele Symbol: St8sia2^tm1Jxm
• Allele Name: targeted mutation 1, Jamey Marth
• Allele ID: MGI:3051219
• Summary: 3 genotypes

Jump to	Allelic Composition	Genetic Background	Genotype ID
hm1	St8sia2^tm1Jxm/St8sia2^tm1Jxm	involves: C57BL/6	MGI:3051366
cx2	St8sia2^tm1Jxm/St8sia2^tm1Jxm St8sia4^tm1.1Mifu/St8sia4^tm1.1Mifu	involves: C57BL/6	MGI:3762774
cx3	St8sia2^tm1Jxm/St8sia2^tm1Jxm St8sia4^tm1.1Mifu/St8sia4^tm1.1Mifu Tg(Thy1-YFP)HJrs/?	involves: C57BL/6 * CBA	MGI:3762775

Genotype
MGI:3051366

hm1

• Allelic Composition: St8sia2^tm1Jxm/St8sia2^tm1Jxm
• Genetic Background: involves: C57BL/6

• ♀: phenotype observed in females
• ♂: phenotype observed in males
• N: normal phenotype

behavior/neurological

abnormal passive avoidance behavior ( J:91777 )

• mutants fail to increase their latency to enter the dark chamber in a passive avoidance task

abnormal contextual conditioning behavior ( J:91777 )

• impaired performance in a contextual fear conditioning test is seen

abnormal cued conditioning behavior ( J:91777 )

• impaired performance in a cued fear conditioning test is seen, however, the acoustic startle response is normal

increased exploration in new environment ( J:91777 )

• mutants are more active in the open field test, spend more time in the center of the field, and rear more frequently, however, mutants are not hyperactive

nervous system

abnormal hippocampus morphology ( J:91777 )

• abnormal mossy fibers on the ventral side of the granule cell layer are associated with ectopic synapses

abnormal hippocampal mossy fiber morphology ( J:91777 )

• the infrapyramidal mossy fibers extend into the faeCA3a region and into the CA3b and CA3c regionsfrom the age of 2 weeks on

• mossy fibers also extend along the ventral side of the granule cell layer

Genotype
MGI:3762774

cx2

• Allelic Composition: St8sia2^tm1Jxm/St8sia2^tm1Jxm; St8sia4^tm1.1Mifu/St8sia4^tm1.1Mifu
• Genetic Background: involves: C57BL/6

mortality/aging

postnatal lethality, complete penetrance ( J:126687 )

• most mice die between P0 and P10 with some mice surviving until P20

nervous system

increased neuron apoptosis ( J:126687 )

• neurons and their precursors in the cortex and subventricular zone undergo more apoptosis than in wild-type mice

• however, hippocampal cells do not undergo apoptosis except for those located in the lateral ventricle

abnormal neuron differentiation ( J:126687 )

• in culture, neurospheres differentiate into GFAP+ cells that have astrocyte-like morphology unlike wild-type neurospehre cells

• in the presence of PDGF more neurospheres differentiated into GFAP+ cells (47.0+/-1.5% compared to 31.6+/-4.8% of wild-type neurospheres) while in the presence of BDNF fewer do so (21.6+/-5.8% compared to 25.6+/-5.2 of wild-type neurospheres)

impaired neuronal migration ( J:126687 )

• neuron migration is impaired and in culture neurons move 8 to 15% slower than wild-type neurons when plated on laminin

• however, proliferation and differentiation of neurons is normal

abnormal brain morphology ( J:126687 )

abnormal rostral migratory stream morphology ( J:126687 )

• at P0 the rostral migratory stream is thicker than in wild-type mice but by P10 it is thinner than in wild-type mice

abnormal brain interneuron morphology ( J:126687 )

• GABAnergic interneurons in the cerebral cortex are decreased to 20% of the number found in wild-type mice

abnormal lateral ventricle morphology ( J:126687 )

• hippocampal cells located in the lateral ventricle undergo apoptosis

dilated lateral ventricle ( J:126687 )

• coronal and sagittal brain sections reveal an increase in the size of the lateral ventricle as well as a thinner cortex

• lateral ventricles increase with age

abnormal corpus callosum morphology ( J:126687 )

• the corpus callosum is thinner than in wild-type mice or partially absent

decreased striatum size ( J:126687 )

• the striatum is thinner than in wild-type mice

abnormal diencephalon morphology ( J:126687 )

• the diencephalons is thinner than in wild-type mice

loss of hippocampal neurons ( J:126687 )

• hippocampal cells located in the lateral ventricle undergo apoptosis

abnormal cerebral cortex morphology ( J:126687 )

• mice have fewer cortical cells than in wild-type mice

• neurons and their precursors in the cortex and subventricular zone undergo more apoptosis than in wild-type mice

• GABAnergic interneurons in the cerebral cortex are decreased to 20% of the number found in wild-type mice

decreased cerebral cortex pyramidal cell number ( J:126687 )

• in layers II/III and IV of the neocortex

ectopic cerebral cortex pyramidal cells ( J:126687 )

• unlike in wild-type mice, pyramidal cells are detected in the subventricular zone

thin cerebral cortex ( J:126687 )

• coronal and sagittal brain sections reveal an increase in the size of the lateral ventricle as well as a thinner cortex

• the cerebral cortex becomes thinner with age

small olfactory bulb ( J:126687 )

• at P10, the olfactory bulb is smaller than in wild-type mice due to impaired movement of neuroblasts from the sub-ventricular zone to the olfactory bulb

small cerebellum ( J:126687 )

abnormal postnatal subventricular zone morphology ( J:126687 )

• neurons and their precursors in the cortex and subventricular zone undergo more apoptosis than in wild-type mice

• unlike in wild-type mice, pyramidal cells are detected in the subventricular zone

abnormal CNS glial cell morphology ( J:126687 )

• glial cell migration is impaired whereby GFAP+ cells are confined to the subventricular zone close to the lateral ventricle

• unlike in wild-type mice, GFAP+ cells exhibit an elongated morphology

abnormal astrocyte morphology ( J:126687 )

• the number of GFAP+ astrocytes in the hippocampus is decreased to 30% of wild-type hippocampus

behavior/neurological

abnormal motor capabilities/coordination/movement ( J:126687 )

• mice exhibit slow, weak and uncoordinated movements

growth/size/body

decreased body size ( J:126687 )

• mice are smaller than normal

cellular

increased neuron apoptosis ( J:126687 )

• neurons and their precursors in the cortex and subventricular zone undergo more apoptosis than in wild-type mice

• however, hippocampal cells do not undergo apoptosis except for those located in the lateral ventricle

abnormal neuron differentiation ( J:126687 )

• in culture, neurospheres differentiate into GFAP+ cells that have astrocyte-like morphology unlike wild-type neurospehre cells

• in the presence of PDGF more neurospheres differentiated into GFAP+ cells (47.0+/-1.5% compared to 31.6+/-4.8% of wild-type neurospheres) while in the presence of BDNF fewer do so (21.6+/-5.8% compared to 25.6+/-5.2 of wild-type neurospheres)

impaired neuronal migration ( J:126687 )

• neuron migration is impaired and in culture neurons move 8 to 15% slower than wild-type neurons when plated on laminin

• however, proliferation and differentiation of neurons is normal

Genotype
MGI:3762775

cx3

• Allelic Composition: St8sia2^tm1Jxm/St8sia2^tm1Jxm; St8sia4^tm1.1Mifu/St8sia4^tm1.1Mifu; Tg(Thy1-YFP)HJrs/?
• Genetic Background: involves: C57BL/6 * CBA

nervous system

abnormal cerebral cortex pyramidal cell morphology ( J:126687 )

• unlike in wild-type mice, the projections of dendrites and axons from pyramidal cells are disorganized

decreased cerebral cortex pyramidal cell number ( J:126687 )

• the number of pyramidal cells is decreased to 25% of that in wild-type mice