A Transgenic Approach to QTL analysis in a Trypanotolerant Mouse Model

1
A Transgenic Approach to QTL analysis in a
Trypanotolerant Mouse Model
Anderson SI1 Noyes HA2 Agaba M3 Ogugo
M3 Kemp SJ2,3 Archibald AL1
1 Roslin
Institute (Edinburgh) Roslin Midlothian EH25
9PS UK 2 School of Biological Sciences University
of Liverpool Crown Street Liverpool L69 7ZB
UK 3 International Livestock Research
Institute, P.O. Box 30709 Nairobi 00100 Kenya
Introduction We are using a mouse model to
investigate the genetic basis of trypanotolerance
in African cattle. We have used a transgenic
approach in order to evaluate candidate genes
underlying a Quantitative Trait Locus (QTL) for
trypanotolerance (Tir1) in mice identified in an
earlier study. BAC clones from the
trypanotolerant C57BL/6 underlying the Tir1 QTL
for response to infection with Trypanosoma
congolense were microinjected into F1 A/J x
Balb/c (susceptible) donor oocytes fertilised
with an A/J male. Transgenic animals were
repeatedly backcrossed to A/J with genotyping for
the transgene at every generation, and finally
intercrossed prior to trypanosome challenge.

survival
survival
0-40 41-50 51-60 61-70 71-80
81-90 91-100 Days post-infection
0-40 41-50 51-60 61-70 71-80
81-90 91-100 Days post-infection

Results and conclusions This method enables the
dissection of large QTL areas in order to assess
the effect of candidate genes, however transgene
content of these mouse lines suggests that
introducing linear BAC DNA by microinjection
results in truncation of the BAC DNA by either
shearing and/or recombination. We have
successfully created BAC transgenic mice in a
strain not commonly used for microinjection by
manipulating factors influencing oocyte quality.
A slight increase in survival at day 95 is
seen in the TRA line. This is stronger in the
mice homozygous for the transgene. SNP
genotyping is underway to investigate a possible
heterozygote effect on survival time. The TRB
line showed no variation in survival time
compared to the non-transgenic control, which may
rule out the genes carried by this BAC as
candidates.
Acknowledgements We thank staff at the Roslin
Small Animal Unit for microinjections and care of
animals. This work was supported by the Wellcome
Trust.