Te. Steeves et Dk. Gardner, Temporal and differential effects of amino acids on bovine embryo development in culture, BIOL REPROD, 61(3), 1999, pp. 731-740
The aim of the study was to determine the amino acid requirements of the in
vitro-produced bovine embryo as it develops from the zygote to the blastoc
yst, using a two-step culture system. When added to synthetic oviduct fluid
(SOF) for the first 72-h culture, Eagle's nonessential amino acids and glu
tamine (NeGln) significantly increased development to the 8- to 16-cell sta
ge (Day 4 postinsemination [pi]) and subsequent blastocyst development (Day
7 pi). Glutamine alone during the first 72-h culture did not stimulate dev
elopment to the 8- to 16-cell stage (p > 0.05); however, the removal of glu
tamine from NeGln reduced the stimulatory effects of the nonessential amino
acids. Replacing glutamine with betaine (an organic osmolyte) in NeGln did
not stimulate development to the 8- to 16-cell stage compared to culture i
n SOF, but it did improve subsequent blastocyst development, indicating an
osmolytic function of glutamine during the first 72-h culture. The addition
of Eagle's essential amino acids and glutamine to SOF, or to medium alread
y containing nonessential amino acids and glutamine for the first 72-h cult
ure, did not affect cleavage to the 8- to 16-cell stage or subsequent blast
ocyst development (p > 0.05). Beyond Day 4 pi, culture with 20aa (nonessent
ial and essential amino acids and glutamine) increased blastocyst developme
nt, total cell number, and the number of cells in both the trophectoderm an
d inner cell mass, compared to culture with other groups of amino acids (p
< 0.05). Substituting betaine for glutamine in 20aa reduced blastocyst form
ation, indicating a non-osmolytic function of glutamine during the second 7
2-h culture, Further, there was a significant negative correlation between
the concentration of essential amino acids (quarter, half, or single streng
th) and embryo development during both the first 72-h and second 72-h cultu
re (p < 0.01), indicating that the concentration of essential amino acids w
as too high during culture of the bovine embryo. This study identified the
temporal and differential effects of amino acids during development of the
bovine embryo from the zygote to the blastocyst.