M.L. Leibfried-Rutledge

Bio: M.L. Leibfried-Rutledge is an academic researcher from University of Wisconsin-Madison. The author has contributed to research in topics: In vitro maturation & Human fertilization. The author has an hindex of 18, co-authored 21 publications receiving 3269 citations.

Timing of nuclear progression and protein synthesis necessary for meiotic maturation of bovine oocytes.

Abstract: In cows, protein synthesis is required for germinal vesicle breakdown (GVBD). This study examines more closely the need for protein synthesis and the nuclear changes in the bovine oocyte during 24 h of culture. Bovine oocytes with compact and complete cumulus were washed and incubated in groups of 10 for up to 24 h in SO-pd drops of TCM-199 supplemented with follicle-stimulating hormone (NIAMADD, 0.5 �.Lg/ml), luteinizing hormone (LH) NJAMADD, 5 �.tg/ml), estradiol-17fi (1 �.tg/ml), pyruvate (20 pM), and 10% heattreated fetal calf serum. Medium was overlaid with paraffin oil. Oocytes (n = 891) were fixed at the end of each 3-h interval from 0 to 24 h of culture, or at 24 h after addition of cycloheximide (10 pg/ml at 10 different times during maturation (0, 1, 2, 3, 6, 9, 12, 15, 18, 21 h; n = 175). At each time point, the chromosomal status of oocytes was evaluated, frequencies were computed, and the time spent on each step was determined. The germinal vesicle (GV) was present from 0 to 6.6 h, GVBD at 6.6 to 8.0 h, chromatin condensation at 8.0 to 10.3 h, metaphase I at 10.3 to 15.4 h, anaphase I at 15.4 to 16.6, telophase I at 16.6 to 18.0 h, and metaphase II at 18.0 to 24 h. Cycloheximide blocked oocyte maturation at GVBD, if added from 0 to 3 h; at chromatin condensation, 4fpresent from 6 to 24 h; and at metaphase 1, when present from 9 to 12 h. When cycloheximide was present from 12 to 24 h an increasing number of oocytes reached metaphase II (19% for 12 h, 36% for 15 h, 51% for 18 h, 90% for 21 h, 94% for 24 h), but many abnormalities were noted:

The culture of bovine oocytes to obtain developmentally competent embryos.

Abstract: Bovine cumulus-oocyte complexes (COC) (n = 4230) were used in this study to assess the effects of culture method, hormonal supplementation, and cumulus cell concentration on maturation, fertilization and development of resulting embryos. Five treatments were evaluated. 1) 10 COC/50-microliter drops under oil in TCM 199 supplemented with 10% heat-treated fetal calf serum, follicle-stimulating hormone (0.5 microgram/ml), luteinizing hormone (5 micrograms/ml), and estradiol-17 beta (1 microgram/ml); 2) as in 1 without hormones; 3) as in 1 but in 3 ml TCM-199 in petri dishes without paraffin oil; 4) as in 2 but only 1 COC/50-microliter drop; and 5) as in 1 but with denuded oocytes. After 24 h maturation, the frequencies of oocytes reaching metaphase II were 98, 84, 92, 93, and 87%, respectively, for the five treatments. In the same order, percentages of normal fertilization were 73, 70, 62, 81, and 62%, and the frequencies of embryos containing two or more blastomeres at 65 h postinsemination were 69, 82, 66, 51, and 43%. The same five treatments were used in a second study in which 3,199 oocytes were fertilized, allowed to cleave in vitro to the 2- to 3-cell stage (42 h postinsemination), and transferred to oviducts of sheep (one treatment/oviduct) for 4 days. The frequencies of morulae or blastocytes obtained were 28, 18, 23, 24, and 11% for the five treatments, respectively. After nonsurgical transfer to bovine recipients (n = 8) using fresh or frozen-thawed embryos, three pregnancies past 50 days were obtained. Only one went to term with the birth of a live heifer calf.

Development potential of bovine oocytes matured in vitro or in vivo.

Abstract: Bovine oocytes matured in vivo or in vitro were evaluated after sperm-oocyte incubation for frequency of sperm penetration, frequency of male pronuclei formation, and embryonic development. The frequency of sperm penetration was not different for in vitro matured oocytes (216/295, 73%) vs. in vivo matured oocytes (119/176, 70%). However, formation of male pronuclei was reduced (p less than 0.05) for oocytes matured in vitro (149/216, 69%) vs. in vivo (104/119, 88%). Early embryonic development was evaluated 48 h after the onset of sperm-egg incubations. In vitro matured and fertilized oocytes failed to develop to the 2-cell stage (3/88, 3%), whereas oocytes matured in vivo showed normal development (23/56, 40%) to the 2- and 4-cell stage. Development to the blastocyst stage was evaluated after 5 days in ovine oviducts (in vivo). Morulae and blastocysts were obtained only after in vitro fertilization from oocytes that were in vivo-matured (recovered from oviduct, 14/56, 25%; recovered from follicle, 36/80, 45%). Oocytes that were matured in vitro and fertilized in vitro failed to develop to morulae (0/33) in vivo.

Capacitation of bovine sperm by heparin.

Abstract: Capacitation of bovine sperm was evaluated by determining the ability of sperm to fertilize bovine oocytes in vitro and to undergo an acrosome reaction upon exposure to lysophosphatidylcholine (LC). Incubation of sperm with heparin (10 micrograms/ml) increased the percentage of oocytes fertilized, but this required exposing sperm to heparin for at least 4 h before adding them to oocytes. There was no effect on the percentage of motile or acrosome-reacted sperm after exposure of noncapacitated sperm to 100 micrograms/ml LC for 15 min. When sperm were incubated for 4 h with heparin, exposure to 100 micrograms/ml LC for 15 min had no effect on the percentage of sperm that were motile, but the percentage of acrosome-reacted sperm increased from less than 10% to over 70%. The acrosome reactions (ARs) induced by LC were synchronous, reached maximal levels within 15 min, and differed (p less than 0.001) between sperm incubated under capacitating (with heparin) and noncapacitating conditions (without heparin). The time course required for heparin to capacitate sperm as judged by in vitro fertilization and to render sperm sensitive to LC induction of the AR were found to be similar. The percentage of ARs induced by LC and percentage of oocytes fertilized by sperm were found to be heparin-dose-dependent, with the maximum responses occurring at 5-10 micrograms/ml heparin. The correlation between the mean fertilization and LC-induced AR percentages was 0.997 (p less than 0.01). These studies demonstrate capacitation of bovine sperm by heparin requires at least a 4-h exposure of sperm to heparin and suggest that plasma membrane changes prior to an AR can be detected by exposure of bovine sperm to LC.

Consequences of bovine oocyte maturation, fertilization or early embryo development in vitro versus in vivo: implications for blastocyst yield and blastocyst quality.

Abstract: The aim of this study is to examine the effect of bovine oocyte maturation, fertilization or culture in vivo or in vitro on the proportion of oocytes reaching the blastocyst stage, and on blastocyst quality as measured by survival following vitrification. In Experiment 1, 4 groups of oocytes were used: (1) immature oocytes from 2-6 mm follicles; (2) immature oocytes from > 6 mm follicles; (3) immature oocytes recovered in vivo just before the LH surge; and (4) in vivo matured oocytes. Significantly more blastocysts developed from oocytes matured in vivo than those recovered just before the LH surge or than oocytes from 2-6 mm follicles. Results from > 6 mm follicles were intermediate. All blastocysts had low survival following vitrification. In Experiment 2, in vivo matured oocytes were either (1) fertilized in vitro or (2) fertilized in vivo by artificial insemination and the resulting presumptive zygotes recovered on day 1. Both groups were then cultured in vitro. In vivo fertilized oocytes had a significantly higher blastocyst yield than those fertilized in vitro. Blastocyst quality was similar between the groups. Both groups had low survival following vitrification. In Experiment 3a, presumptive zygotes produced by in vitro maturation (IVM)/fertilization (IVF) were cultured either in vitro in synthetic oviduct fluid, or in vivo in the ewe oviduct. In Experiment 3b, in vivo matured/in vivo fertilized zygotes were either surgically recovered on day 1 and cultured in vitro in synthetic oviduct fluid, or were nonsurgically recovered on day 7. There was no difference in blastocyst yields between groups of zygotes originating from the same source (in vivo or in vitro fertilization) irrespective of whether culture took place in vivo or in vitro. However, there was a dramatic effect on blastocyst quality with those blastocysts produced following in vivo culture surviving vitrification at significantly higher rates than their in vitro cultured counterparts. Collectively, these results indicate that the intrinsic quality of the oocyte is the main factor affecting blastocyst yields, while the conditions of embryo culture have a crucial role in determining blastocyst quality.

Production of Cloned Calves Following Nuclear Transfer with Cultured Adult Mural Granulosa Cells

Abstract: Adult somatic cell nuclear transfer was used to determine the totipotent potential of cultured mural granulosa cells, obtained from a Friesian dairy cow of high genetic merit. Nuclei were exposed to oocyte cytoplasm for prolonged periods by electrically fusing quiescent cultured cells to enucleated metaphase II cytoplasts 4-6 h before activation (fusion before activation [FBA] treatment). Additionally, some first-generation morulae were recloned by fusing blastomeres to S-phase cytoplasts. A significantly higher proportion of fused embryos developed in vitro to grade 1-2 blastocysts on Day 7 with FBA (27.5 +/- 2.5%) than with recloning (13.0 +/- 3.6%; p < 0. 05). After the transfer of 100 blastocysts from the FBA treatment, survival rates on Days 60, 100, 180, and term were 45%, 21%, 17%, and 10%, respectively. Ten heifer calves were delivered by elective cesarean section; all have survived. After the transfer of 16 recloned blastocysts, embryo survival on Day 60 was 38%; however, no fetuses survived to Day 100. DNA analyses confirmed that the calves are all genetically identical to the donor cow. It is suggested that the losses throughout gestation may in part be due to placental dysfunction at specific stages. The next advance in this technology will be to introduce specific genetic modifications of biomedical or agricultural interest.