Analysis Tools
mortality/aging
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• only 11/200 animals survive past weaning and live up to 7 months
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• homozygotes usually die in third week after birth
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growth/size/body
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• mice show severe growth retardation in the second week after birth; mice that survive through weaning are severely runted
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• at time of death, weight is ~1/3 weight of littermates
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behavior/neurological
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• mice consistently flex both hindlimbs and sometimes their forelimbs upon tail suspension, while wild-type mice extend their legs
• behavior is pronounced in young animals 2-3 weeks of age, but becomes attenuated in adults which usually clasp only 1 hindleg
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nervous system
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• at E16.5 posterior region of the collicular neuroepithelium is detectably shorter and thinner vs wild-type
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• mice show altered cerebellar foliation pattern
• lobule culmen is divided by a deep intraculminate fissure
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• structure is dramatically reduced in central region around midline while appearing normal on lateral sides
• however, superior colliculus is of normal size
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• culmen of cerebellum is expanded anteriorly
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• minor change in folding of tuber vermis is observed
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immune system
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• fetal liver does not support B cell lymphopoiesis; wild-type and heterozygous livers contain only 3-4% B lymphocytes in total population but mutants have no B lymphocytes at E17
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• incidence of V to DJ heavy chain rearrangements is 50- to 70-fold reduced in mutant pre-BI cells compared to wild-type; D to J rearrangements are not affected
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• at 2 weeks of age, numbers of immature B cells in spleen are considerably reduced; similar results are found in bone marrow and lymph nodes
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• B cell development is stopped at early stage; B cells are large and express CD43 and B220 on the surface consistent with early precursor stage
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• mutants lack mature B cells
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• at 2 weeks, peritoneum is devoid of conventional B cells and mature B-1 cells
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• at 2 weeks, peritoneum is devoid of conventional B cells
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• mature T cells are present in spleen
• number of mature T cells appears increased 2- to 4-fold as result of deletion of mature B cells
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• no immunoglobulin is detected above detection limit compared to normal concentrations in wild-type and heterozygotes
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hematopoietic system
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• fetal liver does not support B cell lymphopoiesis; wild-type and heterozygous livers contain only 3-4% B lymphocytes in total population but mutants have no B lymphocytes at E17
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• incidence of V to DJ heavy chain rearrangements is 50- to 70-fold reduced in mutant pre-BI cells compared to wild-type; D to J rearrangements are not affected
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• at 2 weeks of age, numbers of immature B cells in spleen are considerably reduced; similar results are found in bone marrow and lymph nodes
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• B cell development is stopped at early stage; B cells are large and express CD43 and B220 on the surface consistent with early precursor stage
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• mutants lack mature B cells
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• at 2 weeks, peritoneum is devoid of conventional B cells and mature B-1 cells
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• at 2 weeks, peritoneum is devoid of conventional B cells
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• mature T cells are present in spleen
• number of mature T cells appears increased 2- to 4-fold as result of deletion of mature B cells
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• no immunoglobulin is detected above detection limit compared to normal concentrations in wild-type and heterozygotes
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hearing/vestibular/ear
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• at 13-19 days of age, homozygotes exhibit normal auditory responses and audiograms relative to wild-type mice, suggesting that the affected central region of the inferior colliculus is not important for hearing, at least as assessed by early brainstem auditory evoked potential (BAEP) measurements
• however, development of auditory sensitivity is delayed by at least 1 day, and peak latencies of BAEPs for waves II and IV are significantly longer, consistent with a general growth retardation
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