Comparative analysis of Piezo-ICSI and conventional ICSI in bovine embryo development.

Intracytoplasmic sperm injection (ICSI) is an assisted reproductive technique (ART) mainly used to overcome severe male factor infertility problems in humans and animals. However, in cattle, one of the most demanded species for its meat and milk, the efficiency of this technique is low. The present study compared the effect of the piezoelectric and conventional injection systems on the preimplantational development and quality of bovine embryos generated by ICSI.

Production of bovine embryos by piezo-ICSI using capacitated spermatozoa selected by fluorescence-activated cell sorting (FACS-piezo-ICSI).

Intracytoplasmic sperm injection (ICSI) remains inefficient in cattle. One reason could lie in the injection of oocytes with sperm that have not undergone molecular changes associated with in vivo capacitation and fertilizing ability. This study aimed to enhance the efficiency of bovine intracytoplasmic sperm injection (piezo-ICSI) by employing fluorescent-activated cell sorting (FACS) to select the sperm population before injection based on capacitation markers.

Effect of exogenous sperm capacitation inducers on stallion sperm.

Although under appropriate laboratory conditions, sperm from different mammalian species can be capacitated in vitro, the optimal conditions for sperm capacitation in the stallion have been elusive. This study evaluated the effect of different capacitating inducers in Whitten and Tyrode media and assessed their impact on capacitation-related factors. Stallion sperm were incubated with different combinations of capacitating inducers at 38.

Autophagy is activated in human spermatozoa subjected to oxidative stress and its inhibition impairs sperm quality and promotes cell death.

Study Question: Does oxidative stress (OS) activate autophagy in human sperm?

Summary Answer: Human spermatozoa subjected to OS activate an autophagic response.

What Is Known Already: Autophagy is a regulated pathway of lysosomal degradation which helps eukaryotic cells to maintain or restore homeostasis, being a cellular stress response mechanism. OS is a main cause of impaired sperm function and is linked to male infertility; however, whether OS activates autophagy in human spermatozoa is unknown.

Endocrine disruptor chemicals. A review of their effects on male reproduction and antioxidants as a strategy to counter it.

Endocrine disruptor chemicals are exogenous molecules that generate adverse effects on human health by destabilizing the homeostasis of endocrine system and affecting directly human reproductive system by inhibiting or activating oestrogenic or androgenic receptors. Endocrine disruptor chemicals generate transgenerational epigenetic problems, besides being associated with male infertility. Epidemiological data indicate that the increase in reproductive problems in males in the last 50 years is correlated with the increase of endocrine disrupting chemicals in the environment, being associated with a decrease in semen quality and direct effects on spermatozoa, such as alterations in motility, viability and acrosomal reaction, due to the generation of oxidative stress, and have also been postulated as a possible cause of testicular dysgenesis syndrome.

Overtime expression of plasma membrane and mitochondrial function markers associated with cell death in human spermatozoa exposed to nonphysiological levels of reactive oxygen species.

In many cell types, the potential of reactive oxygen species to induce death processes has been largely demonstrated. Studies in spermatozoa have associated the imbalance of reactive oxygen species and phosphatidylserine externalisation as an apoptosis marker. However, the lack of consensus about time effect in the joint expression of these and other death markers has made it difficult to understand the set of mechanisms influenced beyond the concentration effect of reactive oxygen species to stimulate cell death.

Multiparameter Flow Cytometry Assay for Analysis of Nitrosative Stress Status in Human Spermatozoa.

Male infertility is an increasing health problem, and oxidative/nitrosative stress plays an important role in the etiology of this condition. Nitrosative stress due to excessive levels of reactive nitrogen species (RNS) is associated with impaired male fertility. Flow cytometry may be a useful tool for semen evaluation, but the availability of multiparameter assays for analysis of sperm quality is limited.

Antioxidant effects of penicillamine against in vitro-induced oxidative stress in human spermatozoa.

Oxidative stress contributes importantly to the aetiology of male infertility, impairing sperm function. The protective effect of antioxidants on seminal parameters has been established, and the antioxidant penicillamine has shown beneficial effects; however, its protective effect on human spermatozoa exposed to oxidative stress has not been reported. The objective of this work was to evaluate the effect of penicillamine on human spermatozoa exposed in vitro to oxidative stress.

Conventional freezing vs. cryoprotectant-free vitrification of epididymal (MESA) and testicular (TESE) spermatozoa: Three live births.

Data of cryoprotectant-free vitrification of human testicular and epididymal spermatozoa are limited. The aim of this investigation was to compare two aseptic technologies of TESE (testicular) and MESA (epididymal) spermatozoa cryopreservation: standard conventional freezing with the use of cryoprotectants and cryoprotectant-free vitrification. Sperm motility, capacitation-like changes, acrosome reaction and the mitochondrial membrane potential of frozen (5% glycerol, -10 °C/min) and vitrified (Human Tubal Fluid + 1% Human Serum Albumin+0.

Cryoprotectant-free vitrification of spermatozoa: Fish as a model of human.

Post-thawing motility of spermatozoon, which is directly correlated with the integrity of mitochondrion, is the main parameter for evaluation of respective cryopreservation treatments. In this review, we describe our model of mitochondrial apparatus of spermatozoa and behaviour of this apparatus during cryopreservation. This model shows why a priori the mitochondrial apparatus of the human spermatozoon is expected to be more cryo-stable than the mitochondrial apparatus of the fish spermatozoon.

Nitrosative stress in human spermatozoa causes cell death characterized by induction of mitochondrial permeability transition-driven necrosis.

Peroxynitrite is a highly reactive nitrogen species and a potent inducer of apoptosis and necrosis in somatic cells. Peroxynitrite-induced nitrosative stress has emerged as a major cause of impaired sperm function; however, its ability to trigger cell death has not been described in human spermatozoa. The objective here was to characterize biochemical and morphological features of cell death induced by peroxynitrite-mediated nitrosative stress in human spermatozoa.

Effect of incubation temperature after devitrification on quality parameters in human sperm cells.

Sperm cryopreservation is common in assisted reproduction laboratories, providing a therapeutic option for several clinical conditions. This process has been optimized; however, the effect of post-thaw incubation temperature has been poorly studied. This work analyzed the effect of incubation temperature after devitrification on human sperm quality.

Use of the fluorescent dye tetramethylrhodamine methyl ester perchlorate for mitochondrial membrane potential assessment in human spermatozoa.

Mitochondrial membrane potential (ΔΨm) is an indicator of sperm quality and its evaluation complements the standard semen analysis. The fluorescent dye JC-1 has been widely used to assess sperm ΔΨm; however, some problems have been detected under certain experimental conditions. Another fluorescent compound, tetramethylrhodamine methyl ester perchlorate (TMRM), has been used in somatic cells and bovine spermatozoa but not in human spermatozoa.

Thiol oxidation by nitrosative stress: Cellular localization in human spermatozoa.

Unlabelled: Peroxynitrite is a highly reactive nitrogen species and when it is generated at high levels it causes nitrosative stress, an important cause of impaired sperm function. High levels of peroxynitrite have been shown to correlate with decreased semen quality in infertile men. Thiol groups in sperm are mainly found in enzymes, antioxidant molecules, and structural proteins in the axoneme.

Nitrosative stress by peroxynitrite impairs ATP production in human spermatozoa.

The most toxic species in live systems include reactive nitrogen species such as peroxynitrite, which at high levels induces nitrosative stress. In human spermatozoa, the negative effect of peroxynitrite on motility and mitochondrial membrane potential was recently demonstrated, and the hypothesis of this work is that impairment of ATP production could be one cause of the effect on motility. Therefore, the aim here was to evaluate ATP production by both glycolysis and oxidative phosphorylation (OXPHOS) in spermatozoa exposed to peroxynitrite in vitro.

Mitochondrial outer membrane permeabilization increases reactive oxygen species production and decreases mean sperm velocity but is not associated with DNA fragmentation in human sperm.

Study Hypothesis: Does induction of mitochondrial outer membrane permeabilization (MOMP) in vitro affect specific functional parameters of human spermatozoa?

Study Finding: Our findings show that MOMP induction increases intracellular reactive oxygen species (ROS) and decreases mean sperm velocity but does not alter DNA integrity.

What Is Known Already: MOMP in somatic cells is related to a variety of apoptotic traits, such as alteration of mitochondrial membrane potential (ΔΨm), and increase in ROS production and DNA fragmentation. Although the presence of these apoptotic features has been reported in spermatozoa, to date the effects of MOMP on sperm function and DNA integrity have not been analysed.

Peroxynitrite-mediated nitrosative stress decreases motility and mitochondrial membrane potential in human spermatozoa.

Nitrosative stress is produced by high levels of reactive nitrogen species (RNS). The RNS include peroxynitrite, a highly reactive free radical produced from a diffusion-controlled reaction between nitric oxide and superoxide anion. Peroxynitrite causes nitration and oxidation of lipids, proteins and DNA, and is thus considered an important pathogenic mechanism in various diseases.

Assessment of sperm function parameters and DNA fragmentation in ejaculated alpaca sperm (Lama pacos) by flow cytometry.

Flow cytometry has been shown to be an accurate and highly reproducible tool for the analysis of sperm function. The main objective of this study was to assess sperm function parameters in ejaculated alpaca sperm by flow cytometry. Semen samples were collected from six alpaca males and processed for flow cytometric analysis of sperm viability and plasma membrane integrity using SYBR-14⁄PI staining; acrosomal membrane integrity using FITC-conjugated Pisum Sativum Agglutinin⁄PI labelling; mitochondrial membrane potential (Δψm) by staining with JC-1 and DNA Fragmentation Index (DFI) by TUNEL.

Human sperm chemotaxis depends on critical levels of reactive oxygen species.

Objective: To verify whether chemotaxis is in part an oxidative process mediated by reactive oxygen species (ROS).

Design: In this prospective study, after removal of seminal plasma, the sperm suspension received no treatment (control), ROS formation by stimulation with phorbol 12-myristate 13-acetate (PMA), antioxidant treatment (with catalase), or PMA stimulus in the presence of catalase. At time zero and after 3 hours of incubation, the percentage of capacitated and oriented spermatozoa and the ROS levels were determined.

Trypsin and chymotrypsin are involved in the progesterone-induced acrosome reaction in canine spermatozoa.

Acrosomal proteases allow the spermatozoon not only to cross the cumulus cells and penetrate the zona pellucida of the oocyte, but also they are needed for the acrosome reaction process (AR). The present study evaluated in vitro the role of trypsin and chymotrypsin in the acrosome reaction of canine spermatozoa by means of protease inhibitors. Spermatozoa obtained from the second fraction of the ejaculate and devoid of seminal plasma were re-suspended in canine capacitation medium (CCM) and incubated at 38.

Effect of protease inhibitors on the acrosome reaction and sperm-zona pellucida binding in bovine sperm.

Acrosomal proteases participate in several events during fertilization process and are necessary during the acrosome reaction (AR) and sperm-zona pellucida (ZP) binding process. In this study, the participation of sperm trypsin-like, chymotrypsin-like, and metalloprotease enzymes in the AR and ZP binding in cattle was investigated using protease inhibitors. Motile bovine sperm were obtained by a swim-up method (4 x 10(6) cells / ml) in Brackett and Oliphant medium.

Effects of arachnotoxin on intracellular pH and calcium in human spermatozoa.

Objective: To determine the effect of arachnotoxin (ATx), a venom extracted from the Chilean spider Latrodectus mactans, on intracellular calcium ([Ca(2+)](i)) and pH (pH(i)) in capacitated human spermatozoa.

Design: Spermatozoa were collected from fertile adult men (n = 8). Mobile spermatozoa were collected by the "swim up" technique and stimulated with the crude extract of ATx and with progesterone (P).