Bovine oocyte activation with bull or human sperm by conventional ICSI and Piezo-ICSI: Its relationship with PLCɀ activity.

Background: The intracytoplasmic sperm injection (ICSI) technique has low efficiency in cattle. This has mainly been attributed to the oocyte activation failure due to oocyte and/or sperm factors.

Aim: Our aim was to evaluate the effect of conventional ICSI and Piezo-ICSI with bull or human sperm on bovine oocyte activation and embryo development and to assess its relationship with the phospholipase C zeta (PLCɀ) activity of both species.

Variations in metabolic parameters of matured porcine oocytes after vitrification-warming.

Background: As the porcine oocyte is the most sensitive to low-temperature damage, it has been difficult to cryopreserve compared to those from other domestic animals. However, at present, vitrification is used as a method for the cryopreservation of both oocytes and embryos in this species.

Aim: Our aim was to analyze alterations in metabolic parameters in vitrified-warmed matured porcine oocytes at different post-warming recuperation times.

Embryo development after vitrification of immature and in vitro-matured equine oocytes.

Effects of meiotic stage and cumulus status on development of equine oocytes after vitrification was evaluated. Immature oocytes with corona radiata (IMM); in vitro-matured oocytes with corona radiata (MAT CR+); and in vitro-matured oocytes denuded of cumulus (MAT CR-) were vitrified using the Cryotech® method. Warming medium was equilibrated either in 5% CO or Air.

Implications of glycolytic and pentose phosphate pathways on the oxidative status and active mitochondria of the porcine oocyte during IVM.

Glycolysis and the pentose phosphate pathway (PPP) were modulated in porcine cumulus-oocyte complexes during IVM by the addition of inhibitors and stimulators of key enzymes of the pathways to analyze their influence on the oxidative status, active mitochondria, and maturation of the oocyte. The influence of pharmacologic and physiological inhibitors of glycolysis (Sodium fluoride and ATP) and PPP (6-Aminonicotinamide and nicotinamide adenine dinucleotide phosphate) was validated by assessing glucose and lactate turnover and brilliant cresyl blue staining in oocytes. Inhibitors of glycolysis and PPP activity significantly perturbed nuclear maturation, oxidative metabolism (Redox Sensor Red CC-1), and active mitochondria (Mitotracker Green FM) within oocytes (P < 0.

Redox and anti-oxidant state within cattle oocytes following in vitro maturation with bone morphogenetic protein 15 and follicle stimulating hormone.

The developmental competence of cumulus oocyte complexes (COCs) can be increased during in vitro oocyte maturation with the addition of exogenous oocyte-secreted factors, such as bone morphogenetic protein 15 (BMP15), in combination with hormones. FSH and BMP15, for example, induce different metabolic profiles within COCs-namely, FSH increases glycolysis while BMP15 stimulates FAD and NAD(P)H accumulation within oocytes, without changing the redox ratio. The aim of this study was to investigate if this BMP15-induced NAD(P)H increase was due to de novo NADPH production.

Epithelial cadherin is present in bovine oviduct epithelial cells and gametes, and is involved in fertilization-related events.

Fertilization is a calcium-dependent process that involves sequential cell-cell adhesion events of spermatozoa with oviduct epithelial cells (OECs) and with cumulus-oocyte complexes (COCs). Epithelial cadherin (E-cadherin) participates in calcium-dependent somatic cell adhesion; the adaptor protein β-catenin binds to the E-cadherin cytoplasmic domain and links the adhesion protein to the cytoskeleton. The study was conducted to immunodetect E-cadherin and β-catenin in bovine gametes and oviduct (tissue sections and OEC monolayers), and to assess E-cadherin participation in fertilization-related events.

Pentose phosphate pathway activity: effect on in vitro maturation and oxidative status of bovine oocytes.

The relationship between pentose phosphate pathway (PPP) activity in cumulus-oocyte complexes (COCs) and oxidative and mitochondrial activity in bovine oocytes was evaluated with the aim of analysing the impact of two inhibitors (NADPH and 6-aminonicotinamide (6-AN)) and a stimulator (NADP) of the key enzymes of the PPP on the maturation rate, oxidative and mitochondrial activity and the mitochondrial distribution in oocytes. The proportion of COCs with measurable PPP activity (assessed using brilliant cresyl blue staining), glucose uptake, lactate production and meiotic maturation rate diminished when 6-AN (0.1, 1, 5 and 10mM for 22h) was added to the maturation medium (P<0.

Glycolytic pathway activity: effect on IVM and oxidative metabolism of bovine oocytes.

The aim of the present study was to determine the effect of altering glycolytic pathway activity during bovine IVM on the meiotic maturation rate, oxidative activity, mitochondrial activity and the mitochondrial distribution within oocytes. Glycolytic activity was manipulated using two inhibitors (ATP, NaF) and a stimulator (AMP) of key enzymes of the pathway. Inhibition of glucose uptake, lactate production and meiotic maturation rates was observed when media were supplemented with ATP or NaF.

Immature oocyte quality and maturational competence of porcine cumulus-oocyte complexes subpopulations.

Porcine immature oocyte quality (i.e., that of live oocytes at the germinal vesicle stage) was evaluated according to features of the surrounding cumulus, aiming to establish maturational competence of different subpopulations of such cumulus-oocyte complexes.

Reactive oxygen species in bovine oocyte maturation in vitro.

The role of reactive oxygen species (ROS) in the in vitro maturation (IVM) of oocytes remains controversial. The aim of the present study was to determine possible fluctuations in ROS production during bovine oocyte IVM in the presence of different modulators of ROS generation. Cumulus-oocyte complexes were cultured in medium 199 (control) in the absence or presence of 0.

Influence of hyaluronic acid synthesis and cumulus mucification on bovine oocyte in vitro maturation, fertilisation and embryo development.

During cumulus-oocyte complex (COC) maturation, cumulus expansion involves the deposition of mucoelastic compounds, especially hyaluronic acid, synthesised from glucose via the hexosamine biosynthesis pathway. The aim of the present study was to determine the effects of uridine monophosphate (UMP) and 6-diazo-5-oxo-L-norleucine (DON), inhibitors of hyaluronic acid synthesis, during bovine oocyte in vitro maturation (IVM) on cumulus expansion, glucose uptake, protein synthesis, cumulus cell number, meiotic maturation, cleavage rate and subsequent embryo development. A further aim of the study was to examine the effect of hyaluronic acid on sperm capacitation and acrosome reaction in relation to the capacity of COCs to be fertilised in vitro.

Glucosamine supplementation during in vitro maturation inhibits subsequent embryo development: possible role of the hexosamine pathway as a regulator of developmental competence.

Glucose concentration during cumulus-oocyte complex (COC) maturation influences several functions, including progression of oocyte meiosis, oocyte developmental competence, and cumulus mucification. Glucosamine (GlcN) is an alternative hexose substrate, specifically metabolized through the hexosamine biosynthesis pathway, which provides the intermediates for extracellular matrix formation during cumulus cell mucification. The aim of this study was to determine the influence of GlcN on meiotic progression and oocyte developmental competence following in vitro maturation (IVM).