Effects of Different Maturation Systems on Bovine Oocyte Quality, Plasma Membrane Phospholipid Composition and Resistance to Vitrification and Warming

Abstract

The objective of this study was to evaluate the effects of different maturation systems on oocyte resistance after vitrification and on the phospholipid profile of the oocyte plasma membrane (PM). Four different maturation systems were tested: 1) in vitro maturation using immature oocytes aspirated from slaughterhouse ovaries (CONT; n = 136); 2) in vitro maturation using immature oocytes obtained by ovum pick-up (OPU) from unstimulated heifers (IMA; n = 433); 3) in vitro maturation using immature oocytes obtained by OPU from stimulated heifers (FSH; n = 444); and 4) in vivo maturation using oocytes obtained from heifers stimulated 24 hours prior by an injection of GnRH (MII; n = 658). A sample of matured oocytes from each fresh group was analyzed by matrix associated laser desorption-ionization (MALDI-TOF) to determine their PM composition. Then, half of the matured oocytes from each group were vitrified/warmed (CONT VIT, IMA VIT, FSH VIT and MII VIT), while the other half were used as fresh controls. Afterwards, the eight groups underwent IVF and IVC, and blastocyst development was assessed at D2, D7 and D8. A chi-square test was used to compare embryo development between the groups. Corresponding phospholipid ion intensity was expressed in arbitrary units, and following principal components analyses (PCA) the data were distributed on a 3D graph. Oocytes obtained from superstimulated animals showed a greater rate of developmental (P<0.05) at D7 (MII = 62.4±17.5% and FSH = 58.8±16.1%) compared to those obtained from unstimulated animals (CONT = 37.9±8.5% and IMA = 50.6±14.4%). However, the maturation system did not affect the resistance of oocytes to vitrification because the blastocyst rate at D7 was similar (P>0.05) for all groups (CONT VIT = 2.8±3.5%, IMA VIT = 2.9±4.0%, FSH VIT = 4.3±7.2% and MII VIT = 3.6±7.2%). MALDI-TOF revealed that oocytes from all maturation groups had similar phospholipid contents, except for 760.6 ([PC (34:1) + H]+), which was more highly expressed in MII compared to FSH (P<0.05). The results suggest that although maturation systems improve embryonic development, they do not change the PM composition nor the resistance of bovine oocytes to vitrification.

The role of cGMP as a mediator of lipolysis in bovine oocytes and its effects on embryo development and cryopreservation

“…The changes in the lipid structural composition of the membranes, which are not possible to detect using staining procedures, are readily detected by matrix-assisted laser desorption ionization mass spectrometry (MALDI-MS) [ 70 ], and the understanding of lipid membranes composition is fundamental to address the difficulties of post cryopreservation embryo survival. Additionally, the oocyte quality [ 71 ], season of the year [ 72 ] culture conditions [ 46 , 52 , 73 ], cryopreservation method [ 74 ], as well as interactions between these factors [ 75 ], may affect embryo cryotolerance.…”

Relationship between in vitro growth of bovine oocytes and steroidogenesis of granulosa cells cultured in medium supplemented with bone morphogenetic protein-4 and follicle stimulating hormone

“…However, in cattle, no studies have currently reported the production of calves from follicles at stages earlier than preantral follicles. Previous studies described bovine calves derived from IVG oocytes that originated from OCGCs in early antral follicles [5,6,7]; however, their developmental competence to transferable embryos was lower than the competence of in vivo matured oocytes [5][6][7][8][9][10][11][12][13].…”

Lipid droplet phase transition in freezing cat embryos and oocytes probed by Raman spectroscopy

“…Thus, we suggest that incubation might be the source of the differences between COCs and later stages. Mass-spectrometry study evidence that lipid content may differ in fresh and in vitro cultured oocytes and embryos (68,69). These observations are also in agreement with the different biological properties of in vitro and in vivo matured oocytes (70).…”