knabe
Well-known member
interesting read.
translation. even with different selection pressure, or lack of it, it's amazing how much polymorphism there is for some of these genes.
the reason i bring it up is because it's fairly obvious to me that even with literally decades of selection, it is extremely difficult to get animals homozygous for anything.
it's also pretty clear to be able to select for heterozygosity with selection pressure. what would be really cool is to have two pure bred herds that were oppositely homozygous with terminal cattle as the hybrids, maximizing heterozygosity.
it's pretty amazing this happened. amazing that selection pressure is so specific.
http://jas.fass.org/cgi/reprint/74/8/1784.pdf
from the text.
"The genetic background of a population
may prove to be an important factor as DNA markers
linked to QTL are identified. Quantitative trait loci
influencing a trait in one population may have a
different effect, or no effect at all, in another
population due to epistatic interactions of the QTL
with background genes (Pomp, 1994).
Heterozygosity. It was expected that the Lents
population would have the lowest Hl and that the
pooled EPD population would have the highest Hl
because of known inbreeding levels. These expectations
were verified at the IGF-I, PRL, BM2113, and
PIT1 polymorphisms, but not at the K-Cas, B-Lac, or
GH polymorphisms. Selection or drift may be preventing
the latter loci from displaying the expected
consequences of inbreeding."
more interesting mumbo jumbo.
A significant effect of B-Lac on milk yield has been
reported, with increases consistently associated with
the A allele (Geldermann et al., 1985; Aleandri et al.,
1990; Bovenhuis et al., 1992; Cowan et al., 1992;
Bovenhuis and Weller, 1994). Bovenhuis et al. (1992)
and Bovenhuis and Weller (1994) also reported a
significant increase in fat percentage associated with
the B allele. A QTL influencing protein percentage
and yield closely linked to B-Lac was also identified
(Bovenhuis et al., 1992; Bovenhuis and Weller, 1994).
Results from the present study failed to detect a
significant effect of the B-Lac polymorphism on PR-m.
The GH polymorphism investigated in this study
results from a single point mutation that causes either
a leucine (A allele) or valine (B allele) to be
incorporated at amino acid position 127 of GH
(Seavey et al., 1971; Zhang et al., 1992). Eppard et al.
(1992) reported higher milk yields from dairy cows
that received recombinant-derived GH with valine at
position 127, compared to cows receiving GH with
leucine at position 127. These results are consistent
with the present study, in which the GH B allele was
associated with a significant increase in PR-m, explaining
5% of PR-m variability.
translation. even with different selection pressure, or lack of it, it's amazing how much polymorphism there is for some of these genes.
the reason i bring it up is because it's fairly obvious to me that even with literally decades of selection, it is extremely difficult to get animals homozygous for anything.
it's also pretty clear to be able to select for heterozygosity with selection pressure. what would be really cool is to have two pure bred herds that were oppositely homozygous with terminal cattle as the hybrids, maximizing heterozygosity.
it's pretty amazing this happened. amazing that selection pressure is so specific.
http://jas.fass.org/cgi/reprint/74/8/1784.pdf
from the text.
"The genetic background of a population
may prove to be an important factor as DNA markers
linked to QTL are identified. Quantitative trait loci
influencing a trait in one population may have a
different effect, or no effect at all, in another
population due to epistatic interactions of the QTL
with background genes (Pomp, 1994).
Heterozygosity. It was expected that the Lents
population would have the lowest Hl and that the
pooled EPD population would have the highest Hl
because of known inbreeding levels. These expectations
were verified at the IGF-I, PRL, BM2113, and
PIT1 polymorphisms, but not at the K-Cas, B-Lac, or
GH polymorphisms. Selection or drift may be preventing
the latter loci from displaying the expected
consequences of inbreeding."
more interesting mumbo jumbo.
A significant effect of B-Lac on milk yield has been
reported, with increases consistently associated with
the A allele (Geldermann et al., 1985; Aleandri et al.,
1990; Bovenhuis et al., 1992; Cowan et al., 1992;
Bovenhuis and Weller, 1994). Bovenhuis et al. (1992)
and Bovenhuis and Weller (1994) also reported a
significant increase in fat percentage associated with
the B allele. A QTL influencing protein percentage
and yield closely linked to B-Lac was also identified
(Bovenhuis et al., 1992; Bovenhuis and Weller, 1994).
Results from the present study failed to detect a
significant effect of the B-Lac polymorphism on PR-m.
The GH polymorphism investigated in this study
results from a single point mutation that causes either
a leucine (A allele) or valine (B allele) to be
incorporated at amino acid position 127 of GH
(Seavey et al., 1971; Zhang et al., 1992). Eppard et al.
(1992) reported higher milk yields from dairy cows
that received recombinant-derived GH with valine at
position 127, compared to cows receiving GH with
leucine at position 127. These results are consistent
with the present study, in which the GH B allele was
associated with a significant increase in PR-m, explaining
5% of PR-m variability.
