Genetic modulation of AII amacrine cell & type 2 cone bipolar cell numbers in the
mouse retina
Stephanie Ann Leong
Introduction
• Neuronal populations often show a natural variation.
• This natural variation may underlie differences in visual function (possibly acuity).
• This suggests the cell populations are under tight genetic modulation.
• The purpose is to identify potential genes in determining the size neuronal cell populations.
– AII amacrine cells (INL)
– type 2 cone bipolar cells (INL)
Methods
Animals• C57BL/6J (B6/J) and A/J parental strains
• Two F1 crosses (AB6F1, B6AF1)
• 26 recombinant inbred (RI) strains derived from the F1 crosses
• At least 4 animals per RI strain (N=4) with two exceptions
– AXB13 (n=3)
– AXB8 (n=3)
Methods (con’t)
Staining• Animals were perfusion fixed.
• Retinas were dissected and prepared as wholemounts .
• Each retina was labeled using antibodies against syt2 and prox-1 to label type 2 cone bipolar cells and AII amacrine cells, respectively.
Syt2 labeled type 2 cone bipolar cells Prox-1 labeled AII amacrine cells
Field Images
AII amacrine cell
• Amacrine cells work laterally affecting the output from bipolar cells.
• Therefore, natural variation of AII amacrine cells may underlie differences in visual function.
• Cell population number should be under genetic modulation.
Min average : 57,141BXA26
Max average: 86,557BXA2
Results – Prox-1
Prox-1 Histogram
Average intrastrain CoV: 0.047802Percent increase: 51%
Min: 57,141 (BXA26)Max: 86,557 (BXA2)
Coefficient of variance = CoV
QTL for Prox-1chromosome 1
Type 2 Cone Bipolar Cell
• One of ten known bipolar cells.
• Transfers signal from cones to ganglion cells.
• Natural variation of cone bipolar cells may underlie a functional difference in visual acuity.
• Because the cell population number should affect visual acuity, there should be genetic modulation.
Min average : 42,515BXA4
Max average: 60,160 AXB12
Results – Syt2
Syt2 Histogram
Average intrastrain CoV: 0.048613Percent increase: 42%
Min: 42,515 (BXA4)Max: 60,570 (BAF1)
Coefficient of variance = CoV
QTL map for Syt2
Conclusion
• The next step will be identifying the best candidate gene(s) from the QTLs.
• Still have 1 more RI run to count next week which may or may not affect the LRS of the QTL.
End.
Prox1+ AII Amacrine Cells
Average SEM N CoV
BXA26 57,141 334 4 0.011675
BXA25 59,772 1,475 4 0.049368
AXB6 60,318 1,134 4 0.037605
AXB4 60,763 2,682 4 0.088273
BXA7 62,968 1,903 4 0.060449
A/J 63,104 3,412 3 0.093647
AXB18/19/20 64,230 2,148 4 0.06687
C57BL/6J 64,677 1,601 3 0.042865
AXB5 64,964 1,010 4 0.031084
BXA14 65,345 1,120 4 0.034282
AXB10 65,819 1,150 4 0.034944
BXA1 65,905 1,562 4 0.047414
A/J (2) 66,032 561 4 0.016985
AXB13 67,613 2,890 3 0.074022
AXB8 68,055 1,532 3 0.039001
BXA11 69,444 2,766 4 0.079648
AXB23 72,024 1,997 4 0.055441
C57BL/6J (2) 72,323 1,007 4 0.027856
AXB12 73,206 861 4 0.023533
AXB15 74,538 1,684 4 0.045182
BXA12 74,842 2,270 4 0.060667
BXA16 75,398 1,419 4 0.037627
BXA4 75,486 3,560 4 0.094317
AXB2 80,783 2,720 4 0.067342
ABF1 80,882 804 5 0.022216
BAF1 82,050 1,309 9 0.047863
BXA8 82,766 909 4 0.021965
BXA24 83,781 1,486 4 0.035466
BXA13 85,984 2,125 4 0.049422
BXA2 86,557 1,602 4 0.037025
percent increase 51% average 0.047802
Syt2+ Type2 Bipolar Cells
Average SEM N CoV
BXA4 42,515 1,093 4 0.051397
AXB8 44,592 849 4 0.038077
AXB4 47,126 1,293 4 0.054859
A/J 47,450 3,075 3 0.112231
A/J (2) 48,199 1,891 4 0.078486
BXA25 48,569 1,301 4 0.053579
AXB6 49,167 1,867 4 0.075962
AXB15 50,685 981 4 0.038693
BXA8 50,924 710 4 0.027881
AXB18/19/20 51,078 1,246 4 0.048783
BXA14 51,256 1,057 4 0.04123
BXA11 52,277 1,494 4 0.05715
BXA26 52,616 1,194 4 0.04538
BXA2 52,714 2,292 4 0.086975
C57BL/6J 53,326 1,193 3 0.038764
BXA24 53,346 801 4 0.03002
AXB10 53,564 354 4 0.013222
AXB23 54,657 995 4 0.036421
AXB2 54,709 509 4 0.018591
BXA13 54,730 2,648 4 0.096748
AXB5 55,382 667 4 0.024086
AXB13 56,183 1,100 3 0.033902
ABF1 56,538 669 5 0.026453
C57BL/6J (2) 56,737 656 4 0.023137
BXA16 58,666 1,530 4 0.052176
BXA7 58,722 1,347 4 0.04589
BXA1 58,914 1,812 4 0.06153
BXA12 60,051 800 4 0.026636
AXB12 60,160 1,730 4 0.057502
BAF1 60,570 1,264 9 0.062627
percent increase 42% average 0.048613
QTL for Prox-1chromosome 19
QTL prox-1 chromosome 2
QTL syt2 chromosome 4
QTL syt2 chromosome 5
QTL syt2 chromosome 18
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