BREEDING AND GENETICS - American Society of Animal Science

284 Discovery and analysis of bovine liver and muscle
cDNAs. W. C. Warren* and T. Allison, Monsanto Dairy Business,
St. Louis, MO.
Regulation of numerous genes affects expression of complex polygenic
traits, such as milk yield. To help define the genes responsible for expressed
phenotypes in cattle we have started to characterize expressed
sequence tags (EST) from selected tissues. In these studies, adult muscle
and liver mRNA from Holstein cows were isolated and used to create
non-normalized plasmid cDNA libraries. The pSPORT plasmid was
the host vector for directional insertion of muscle and liver cDNA sequences.
Library titers were 8 × 10 5 and 5 × 10 6 clones for muscle
and liver libraries, respectively. In both libraries cDNA insert presence
was > 95% and average size was 1200 and 1700 bp for muscle and
liver libraries, respectively. Individual clones for each library were nucleotide
sequenced at the 5 ′ end and compared to known genes within the
Genebank database using a BLASTN analysis. The number of muscle
sequences queried were 1158, which generated 150 clusters, 719 singletons
and 480 unique clones. A cluster is defined as one or more matching
clones within a library. Singletons are EST’s which match a homolog in
Genebank using a BLASTN cutoff score of 10 −9 , while EST’s were considered
unique when no matching homologs were found in Genebank.
For liver 6532 sequences were queried which generated 727 clusters,
3009 singletons and 1484 unique clones. Both libraries demonstrated
good complexity based on cluster number relative to queried sequences.
In liver the most abundant cDNA clones found were albumin, alpha-
1-microglobulin, and beta or gamma-fibronectin. The muscle demonstrated
a high level of mitochondrial content (∼10%) for EST’s characterized
and type IIx myosin heavy chain was the most abundant EST.
This approach will address a current deficiency in the availability of
bovine ESTs needed to study multi-gene expression, mapping and chromosomal
gene order. To further our understanding of various physiological
states we will use small sets of these well annotated muscle and
liver ESTs to study gene expression.
Key Words: Liver, Muscle, cDNA
286 Investigation of a quantitative trait locus for dairy
form in one family of Holsteins. C. P. Van Tassell 1,2 , T. S.
Sonstegard* 2 , and M. S. Ashwell 2 , 1 Animal Improvement Programs
Laboratory and 2 Gene Evaluation and Mapping Laboratory, Agricultural
Research Service, USDA, Beltsville, MD.
Preliminary analysis of quantitative trait loci (QTL) affecting conformation
traits in seven large US Holstein grandsire families has been
completed. Predicted transmitting abilities from Holstein Association
USA were analyzed for association with marker genotypes using analysis
of variance (ANOVA). Strong evidence (P = 0.000021) was found
for a QTL associated with marker BM203 on chromosome 27 for dairy
form in a single grandsire family. This grandsire had 79 sons represented
in the dairy bull DNA repository (DBDR). The BM203 marker is the
farthest marker from the centromere placed on the USDA Meat Animal
Research Center (MARC) cattle linkage map for chromosome 27. Six
additional microsatellite markers on the MARC map were genotyped
for animals in this family. The grandsire was not heterozygous for two
of these markers. Number of observations (i.e., sons), relative position
from the MARC genetic map, and significance of marker are below for
each marker. High levels of statistical significance provide further evidence
of a QTL on chromosome 27. A more exact genetic location of
the QTL is desired and will be the subject of further study.
Relative
Marker Sons position Significance
(no.) (cM)
BM203 44 64.1 0.00002
BMS1675 0 64.1 ... 1
BMS17052 0 59.2 ... 1
INRA027 32 58.4 0.01658
BMS2116 51 55.4 0.00091
BM1857 42 52.7 0.00064
BMS2137 38 19.3 0.02072
1 Grandsire not heterozygous for this marker.
Key Words: Quantitative Trait Locus, Dairy Form, Genetic Marker
287 Mapping of bovine and ovine genes with intronic
single nucleotide polymorphisms. T. P. L. Smith*, S. C.
Fahrenkrug, M. P. Heaton, S. M. Kappes, E. Casas, R. T. Stone, G.
A. Rohrer, J. W. Keele, R. M. Thallman, and W. W. Laegreid, USDA,
ARS, U.S. Meat Animal Research Center (MARC) Clay Center, NE.
285 Simple genetic test that supports marker assisted
selection to increase retail product yield in cattle. S. C.
Fahrenkrug*, E. Casas, J. W. Keele, and T. P. L. Smith, USDA, ARS,
U.S. Meat Animal Research Center (MARC) Clay Center, NE.
Muscular hypertrophy (mh) is a heritable condition present in many
cattle breeds. Homozygous mh animals display a dramatic increase in
muscle mass resulting in more retail product per carcass. These animals
also efficiently produce lean meat as the result of a marked decrease
in body fat. The use of mh to increase production efficiency has been
limited in the U.S. by problems associated with calving ease of homozygotes.
In contrast, heterozygotes show a 7% increase in retail product
yield without a significant effect on calving ease in mature cows. We
recently determined that mutations in the myostatin gene underlie the
mh phenotype. We have now developed a simple genetic test to allow
for the detection of the myostatin alleles that have been identified in
U.S. cattle populations. Data demonstrating the discriminatory power
of a fluorescent primer based PCR assay is presented. Incorporating
this assay into a breeding program permits exploitation of the positive
aspects imparted by mh in heterozygotes, while neutralizing its negative
effects by avoiding the production of homozygotes.
Key Words: Muscular Hypertrophy, Genetic Test, Breeding Program
The stability of single nucleotide polymorphisms (SNPs) makes them superior
to microsatellites for the establishment of chromosomal segment
identity by descent. In order to assess the utility of this class of marker
in placing genes from the human and/or mouse maps on the maps of
livestock species, we have mapped several genes in the bovine and ovine
genomes via SNPs. Polymorphisms were identified by comparing the
sequence of introns amplified from founder animals of the MARC reference
population using primers developed from exon sequences. All
families of the population in which each polymorphism was informative
were then genotyped by direct sequencing of the introns, and the data
deposited in the MARC database for linkage analysis. In this way, the
genes AKT, CAPN1, CKB, CHGA, MIP2, and IL8 were placed on the
bovine maps of chromosomes 21, 29, 21, 21, 6, and 6, respectively. In
addition, a systematic evaluation of the rate of polymorphism at the
SNP level in bovine DNA is being conducted. The sequencing of a collection
of random clones from three chromosome specific libraries and a
directionally cloned muscle cDNA library has been undertaken to determine
the frequency and distribution of SNPs in bovine genes and intergenic
DNA. Early results indicate that SNPs provide reliable markers
showing Mendelian inheritance, and are common enough to serve as useful
positional makers. The theoretical ability to simultaneously assess
hundreds of genetic loci using SNP markers in combination with highdensity
DNA array hybridization technology warrants the collection of
SNPs informative across all U.S. cattle breeds to support QTL-driven
genotyping efforts.
Key Words: SNPs, Genome Mapping
J. Anim. Sci. Vol. 76, Suppl. 1/J. Dairy Sci. Vol. 81, Suppl. 1/1998 73