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 (quantitative trait locus) map for prox-1

www.GeneNetwork.org

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