Gregory. KE, Echternkamp. SE, Dickerson. GE, Cundiff LV, Koch. RM, Van. Vleck. LD. ..... LH (oW-. 3, AFP 9598B),. NIDDK ovine growth hormone. (oGH-4), and.
962
AL-SHOREPY TABLE
4.
Significance
levels
of orthogonal
contrasts Left
LS, selection ovulation
embryo
survival
eight-cell-stage Advancement study
than
and selection the proportion
may
in a line
1ff 0.05 NS NS NS NS 0.10 NS NS NS NS NS NS
0.06 NS NS NS NS 0.03 NS NS NS 0.19 NS NS
due
selected
selection; UT, of unfertilized
for small
for large litter size of embryos developed
to a change
probably
affected
[19]. stage
in the
by several
genes
litter
in the mouse beyond the
affect
of processes
ultimate
from
independent gle genes
litter
timing
and
ovulation
size
present
of ovulation,
by environmental
through
to term
of ovulation rate may have a significant
the
repthat
complexity
of gestation
(or
those
in the case of UT). While sineffect on variation in litter
size by affecting a single process or through pleiotropy, these selection criteria undoubtedly addressed many loci. The results of this study suggest that the frequencies of alleles affecting some determinant(s) of embryonic stage at implantation have been changed through selection. Alleles
(Ped) (MHC)
of the
preimplantation
embryonic
development
gene, linked to the major histocompatibility complex in the mouse, have been shown to affect rate of division [25]. Ped rate of development
cleavage increased
gene
alleles that resulted in an have more recently been as-
sociated with larger litters [17]. Although changes in the timing of ovulation rate or fertilization cannot be ruled out, it is interesting to speculate that alleles of the Ped gene or loci closely linked to the Ped locus may have been one target of these selection Normally developing at or
beyond
Gates
[12]
the reported
morula that,
criteria. mouse embryos stage
by 3.5
of mouse
LS,
analyses. side
UT
LS
vs. LC
vs.
IX vs.
UT
LS
0.002 NS 0.05 0.04 0.04
0.006 NS
0.20 NS NS NS NS NS NS NS NS NS NS NS
IX,
NS NS NS 0.19 NS NS NS NS NS 0.16
NS NS NS NS NS 0.06
capacity; LC, control. of degenerating embryos;
PTC,
percentage
are days
embryos
early blastocyst, blastocyst, or expanded blastocyst stage by 3.5 days postcoitus, those in the latter two stages had greater implantation success and postimplantation survival rates. A greater proportion
in the
Each selection criterion applied in this study an attempt to increase the frequency of alleles
favorably
univariate
0.04
selection for uterine ova; PD, percentage
of fertilization, or of first cleavage division, a change in the rate of subsequent cell division and embryonic development, or some combination of these factors. Each factor is variation. resents
from
percentage of four-cell embryos; PEC, percentage of eight-cell embryos; PM, percentage of early blastocysts; PB. percentage of blastocysts; PEXB, percentage of expanded bIasdevelopmental stage; SD. standard deviation for developmental stage.
by Day 2 of gestation of average embryonic be
means
IX,
LC
of two-cell embryos; PFC, of morula; PEB, percentage tocysts; STAGE. embryonic cNonsignificant (p > 0.20).
high
IX
0.004
for litter size; IX, index rate; PUFO, percentage
boR
criteriona
Right LS
vs.
0.19 0.01 0.07 NS
STAGE SD
size [18], increased
IX,
NSC 0.20 0.09 0.20 0.13 NS NS
PEXB
of selection
vs. LS
Characteristicb
AL.
side
IX, LS, UT vs.
OR PUFO PD PTC PFC PEC PM PEB PB
ET
expected
to be
postcoitus
[26].
at the
morula,
stages
of embryos
of development
survival. Variability
in the
stage
prolific
previously
breed
expense of their embryos from
of pigs
develop
faster
delayed or the highly
and
with
some of the difference in embryonic survival bebreeds (28]. Results from the present study reveal selection criteria decreased variability among
lations of
mity
over time embryonic
decreased right side
it
was
erations
horn at Day the distribution
3.5
of gesof ovu-
in the pig [29]), the uniforor both. Also, selection
of degenerating While it is not
embryos from
on the which
known
of degenthat they embryos
a horn. these
genetic selection size in the mouse
criteria
perhaps
stage the additional proportion in LC were lost, it is possible variability and the loss of delayed
In summary,
of genes bryonic
uterine altered
described development,
the frequency of the uterus.
developmental erating embryos reflect greater within
(as
contemporaries,
less
explaining tween the that these
the right may have
White
to contribadvanced
than
within Selection
Large
at
variability
embryos tation.
their
were increased
development
has been shown loss [14, 27]; more
to survive at the cohorts. Littermate
Meishan
UT
with
of preimplantation
among littermate pig embryos ute ultimately to embryonic embryos tend less advanced
in LS, IX, and
associated
that affect development. on not
results
for litter changed
provide size the
evidence
that
characteristics of preimplantation emIf the effects of the LS, IX, and UT
these characteristics discernable from
of selection
initial
or for components of litter frequencies of allelic forms
on
these
differed from these analyses. criteria,
litter
one After size
another, 13 genof [S and
EMBRYONIC
IX was significantly preimplantation contributed
greater embryonic
DEVELOPMENT
than that of LC [11]. Changes in development have probably
to response
in litter
size.
IN
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BIOLOGY
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of Nutritional
Effect
VASANTHA
Repletion on Pituitary and Serum Follicle-Stimulating Isoform Distribution in Growth-Retarded Lambs’
PADMANABHAN,2 FRANCIS
Departments
(1992)
KATHLEEN
J.P.
of Pediatrics, Program,
EBLING,3
M. RENO, DOUGLAS
Pharmacology, The Universiiy
MARIA
THOMAS
BORONDY,
L. FOSTER,
and
Biology, Obstetrics and of Michigan, Ann Arbor,
INESE
Hormone
D. LANDEFEW,
Z. BEITINS
Gynecology, Michigan
and Reproductive 49109-0718
Sciences
ABSTRACT Using creases but
nutritionally
in GnRH also
alter
the
ovariectomized restricted diet. ovine
Bioactive
(B)
feeding
increased
both,
pituitary
in the
I-oFSH
isoforms
concentrations
activities.
alter
the
pH
3.5-5.6
In summary,
distribution
This
(
5.6, a mock chromatofocusing
pH
no sample) were similar and averaged 111.0 ± SE). Recovery of B-0FSH in the same pools ± 4.3% and were not significantly different
3.9
±
and
Representative
Serum
oFSH
profiles
5.6% (mean averaged 122.0 between pH
in two
re-
stricted-fed lambs (lambs 769 and 740 with mean concentrations of 1.9 and 5.8 ng/ml I-oFSH, respectively) and one ad libitum-fed lamb (lamb 715 with circulating FSH of 25.6 ng/ml) are depicted in Figure 4 (oW patterns are shown
0.01)
