Effects of various physical stress factors on mitochondrial function and reactive oxygen species in rat spermatozoa

Negative correlations of mitochondrial DNA copy number in commercial frozen bull spermatozoa with the motility parameters after thawing

The purpose of the current study was to investigate the relationship between mitochondrial content of commercial frozen-thawed bull spermatozoa and motility. Firstly, mitochondrial DNA copy number per spermatozoon (MDCN), mitochondrial content (MC), the percentage of spermatozoa with high mitochondrial membrane potential (HMMP), intracellular reactive oxygen species (ROS) and motility parameters of frozen-thawed spermatozoa derived from five bulls were determined by using qPCR, flow cytometry and CASA, respectively, and analyzed the relationships. Results showed that all parameters examined, including MDCN, MC, HMMP, ROS and motility indicators, significantly differed among frozen spermatozoa from different bulls. Both MDCN and MC were negatively correlated with HMMP and motility indicators, but positively with ROS, of course, whereas there was a highly positive relationship between MDCN and MC. Secondly, when MDCN and MC were examined in frozen spermatozoa prepared at different points in the lives of four bulls, those did not correlate overall throughout their lives (1.3-14.3 years old), but did correlate significantly in two sires. From these results, we conclude that MDCN and MC of frozen spermatozoa differ among sires, and are negatively correlated with HMMP and sperm motility parameters, probably due to mitochondrial oxidative stress resulted in the presence of ROS, demonstrating that these appear to be useful markers to assess sires' spermatozoa. It should be noted that the MDCN and MC of bull spermatozoa may not vary overall with the age of the sire, whereas those changes with age in some individuals and may affect sperm motility.

Intensification of Hydrogen Production by a Co-culture of Syntrophomonas wolfei and Rhodopseudomonas palustris Employing High Concentrations of Butyrate as a Substrate

The purpose of this study is to present an effective form of developing a sequential dark (DF) and photo (PF) fermentation using volatile fatty acids (VFAs) and nitrogen compounds as bonding components between both metabolic networks of microbial growing in each fermentation. A simultaneous (co-)culture of Syntrophomonas wolfei (with its ability to consume butyrate and produce acetate) and Rhodopseudomonas palustris (that can use the produced acetate as a carbon source) performed a syntrophic metabolism. The former bacteria consumed the acetate/butyrate mixture reducing the butyrate concentration below 2.0 g/L, permitting Rhodopseudomonas palustris to produce hydrogen. Considering that the inoculum composition (Syntrophomonas wolfei/Rhodopseudomonas palustris) and the nitrogen source (yeast extract) define the microbial biomass specific productivity and the butyrate consumption, a response surface methodology defined the best inoculum design and yeast extract (YE) yielding to the highest biomass concentration of 1.1 g/L after 380.00 h. A second culture process (without a nitrogen source) showed the biomass produced in the previous culture process yields to produce a total cumulated hydrogen concentration of 3.4 mmol. This value was not obtained previously with the pure strain Rhodopseudomonas palustris if the culture medium contained butyrate concentration above 2.0 g/L, representing a contribution to the sequential fermentation scheme based on DF and PF.

Slow release curcumin-containing soy protein nanoparticles as anticancer agents for osteosarcoma: synthesis and characterization

Curcumin-containing soy protein nanoparticles (curcumin-SPNs) were synthesized by desolvation (coacervation) method and characterized by SEM, DLS, FTIR, and XRD. For anticancer evaluation, osteogenic sarcoma (SAOS2) cell lines were incubated with different concentrations of nanostructures. The dialysis method was used for assessment of drug release. Intracellular reactive oxygen species (ROS) were evaluated in IC50 dose after 24 h of exposure to free curcumin and curcumin-SPNs. Characterization data showed that the size of drug-free SPNs and curcumin-SPNs were 278.2 and 294.7 nm, respectively. The zeta potential of drug-free SPNs and curcumin-SPNs were - 37.1 and - 36.51 mv, respectively. There was no significant difference between the control and drug-free SPNs groups in terms of cell viability (p > 0.05). The viability of cells in different concentrations of the designed curcumin-SPNs in Saos2 cell line was significantly higher than free drug (p < 0.05). The release of curcumin showed that more than 50% of the drug was released in the first 2 h of incubation. After this time, the slow release of drug was continued to 62-83% of drug. IC50 values of free curcumin and curcumin-SPNs (1/10) were 156.8 and 65.9 µg/mL, respectively (a free curcumin IC50 was 2.4 times more than curcumin-SPNs). Slow-release of the curcumin causes the cell to be exposed to the anticancer drug for a longer period of time. The intracellular ROS levels significantly increased in an IC50 dose after 24 h of exposure to both free curcumin and curcumin-SPNs compared with controls (p < 0.05).

Sperm Motility of Mice under Simulated Microgravity and Hypergravity

For deep space exploration, reproductive health must be maintained to preserve the species. However, the mechanisms underlying the effect of changes in gravity on male germ cells remain poorly understood. The aim of this study was to determine the effect of simulated micro- and hypergravity on mouse sperm motility and the mechanisms of this change. For 1, 3 and 6 h, mouse sperm samples isolated from the caudal epididymis were subjected to simulated microgravity using a random position machine and 2g hypergravity using a centrifuge. The experimental samples were compared with static and dynamic controls. The sperm motility and the percentage of motile sperm were determined using microscopy and video analysis, cell respiration was determined by polarography, the protein content was assessed by Western blotting and the mRNA levels were determined using qRT-PCR. The results indicated that hypergravity conditions led to more significant changes than simulated microgravity conditions: after 1 h, the speed of sperm movement decreased, and after 3 h, the number of motile cells began to decrease. Under the microgravity model, the speed of movement did not change, but the motile spermatozoa decreased after 6 h of exposure. These changes are likely associated with a change in the structure of the microtubule cytoskeleton, and changes in the energy supply are an adaptive reaction to changes in sperm motility.

Sperm enrichment from poor semen samples by double density gradient centrifugation in combination with swim-up for IVF cycles

Sperm preparation in IVF cycles using density gradient centrifugation (DGC) in combination with swim-up (SU) has been widely adopted in reproductive centres worldwide. It is a fact that the sperm recovery rate following one DGC from poor semen samples (showing liquefaction defects/containing too many unresolvable clots or rare sperm) is relatively low. Our results showed that double DGC (DDGC) is effective at increasing the sperm recovery rate from poor semen samples. However, DDGC may increase the mechanical stress of sperm, thereby potentially impairing embryo development. Therefore, it is necessary to evaluate the safety of using sperm prepared by DDGC/SU for IVF cycles. In this study, we retrospectively analysed the data generated from a total of 529 IVF cycles (from June 2017 to June 2018), and these IVF cycles contributed 622 transfer cycles (from June 2017 to December 2018) in Changzhou Maternal and Child Health Care Hospital. Of them, 306 IVF cycles and the related 355 transfer cycles (normal semen samples prepared by DGC/SU) were set as the normal group, while 223 IVF cycles and the related 267 transfer cycles (poor semen prepared by DDGC/SU) were set as the observation group. The main outcome measures, including the normal fertilization rate, top D3 embryo formation rate, blastocyte formation rate, clinical pregnancy rate and live birth rate, birth weight and duration of pregnancy, were compared between the two groups. Compared to semen in the DGC/SU group, semen in the DDGC/SU group showed increased levels of the DNA fragmentation index (DFI) and reduced sperm concentration, percentage of progressive motility (PR) sperm, and percentage of normal morphology sperm. The indicators reflecting in vitro embryo development and clinical outcomes were similar in the DGC/SU group and DDGC/SU group, including the normal fertilization rate, top D3 embryo formation rate, blastocyte formation rate, pregnancy rate, implantation rate, spontaneous abortion rate, live birth rate, birth weight and duration of pregnancy. Furthermore, we found that the 1PN zygote formation rate was significantly lower in the DDGC/SU group than that in the DGC/SU group. We concluded that oocytes fertilized by sperm from poor semen samples separated by DDGC/SU achieved the same outcomes as oocytes fertilized by sperm from normal semen separated by DGC/SU, suggesting that DDGC/SU is an effective and safe method of sperm enrichment for poor semen samples in IVF. The main contribution of the present study is the verification of the effectiveness of DDGC/SU in improving sperm recovery from poor semen samples and the safety of using sperm prepared by DDGC/SU for IVF.

Centrifugation Force and Time Alter CASA Parameters and Oxidative Status of Cryopreserved Stallion Sperm

Conventional sperm selection techniques used in ARTs rely on centrifugation steps. To date, the different studies reported on the effects of centrifugation on stallion sperm motility provided contrasting results and do not include effects on mitochondrial functionality and different oxidative parameters. The effects of different centrifugation protocols (300 ×g for 5', 300 ×g for 10', 1500 ×g for 5' and 1500 ×g for 10' vs no centrifugation) on motility and oxidative status in cryopreserved stallion sperm, were analyzed. After centrifugation, almost all motility parameters were significantly altered, as observed by computer-assisted sperm analysis. A polarographic assay of oxygen consumption showed a progressive decrease in mitochondria respiration from the gentlest to the strongest protocol. By laser scanning confocal microscopy, significant reduction of mitochondrial membrane potential, at any tested protocol, and time-dependent effects, at the same centrifugal force, were found. Increased DNA fragmentation index at any tested protocol and time-dependent effects at the same centrifugal force were found, whereas increased protein carbonylation was observed only at the strongest centrifugal force. These results provide more comprehensive understandings on centrifugation-induced effects on cryopreserved stallion sperm and suggest that, even at a weak force for a short time, centrifugation impairs different aspects of equine sperm metabolism and functionality.

p53-Dependent pathway and the opening of mPTP mediate the apoptosis of co-cultured Sertoli-germ cells induced by microcystin-LR

Microcystin-LR (MC-LR), a potent endotoxin, can induce reproductive toxicity. In order to investigate the role and mechanisms of apoptosis (p53-dependent and mitochondrial pathways) of germ cells induced by MC-LR, the co-cultured primary Sertoli-germ cells from Sprague-Dawley rats were used for the experiments. Expression levels of proteins, genes, and mitochondrial membrane potential (MMP) were obtained after exposing co-cultured Sertoli-germ cells to MC-LR with or without the addition of the p53 inhibitor, pifithrin-α (PFT-α), and MMP inhibitor, cyclosporin A (CsA). Results indicated that MC-LR could activate p53-dependent pathway-associated proteins in Sertoli-germ cells, leading to a decrease in MMP (indicating the opening of mitochondrial permeability transition pore [mPTP] and the release of Cytochrome-c [Cyt-c]) from the mitochondria into the cytoplasm and eventually the induction of apoptosis. PFT-α inhibited the expression ofp53, ameliorated the MMP of the co-cultured Sertoli-germ cells, and prevented the release of Cyt-c from the mitochondria into the cytoplasm, which reduces the occurrence of apoptosis. Similarly, the decreased release of Cyt-c from the mitochondria into the cytoplasm and the declined level of apoptosis in Sertoli-germ cells induced by MC-LR were observed after the addition of CsA. These results indicated that the apoptosis of the co-cultured Sertoli-germ cells induced by MC-LR was mediated by the p53-dependent pathway, with the involvement of the opening of mPTP.

The in vitro effects of gibberellin on human sperm motility

Gibberellin, a plant growth regulator, is widely used to increase the shelf life and quality of fruits and vegetables. In this study, human semen samples were exposed to different concentrations of gibberellin, which reduced spermatozoa motility in vitro. Gibberellin exposure also increased levels of reactive oxygen species and the protein levels of apoptosis markers in human sperm. Gibberellin inhibited the activity of Na+/K+-adenosine triphosphatase (ATPase) and Ca2+-ATPase, which maintain the stability of ions inside and outside the membranes of spermatozoa. Moreover, gibberellin exposure suppressed adenosine triphosphate production and reduced the protein levels of adenosine triphosphate synthases, which may have induced the protein expression of adenosine 5'-monophosphate-activated protein kinase (AMPK) and its phosphorylated form. These results suggest that gibberellin reduces human sperm motility in vitro by increasing reactive oxygen species levels and reducing ATPase activity, which may upregulate AMPK and consequently reduce the fertilization potential of spermatozoa.

Short-term tolerance of equine spermatozoa to various abiotic factors

The aim of this study was to determine the effects of various abiotic factors, such as light, physical stress (pipetting) and thermal shock, on the quality of fresh and cooled equine sperm. In experiment I, four sperm aliquots were subjected to different light exposures: (i) protected control samples (CTRL), (ii) exposed to UV light at 10 cm (UV10), (iii) exposed to UV light at 20 cm (UV20) and (iv) exposed to laboratory lighting (LAB). In experiment II, four semen aliquots were subjected to repeated pipetting for 0, 10, 20 and 30 times (CTRL, P10, P20 and P30, respectively). In experiment III, four semen aliquots at 15°C were subjected to thermal oscillations: (i) cooled control sperm at 15°C (CTRL), (ii) oscillations of 1.9°C/min to a temperature of 30°C (T30), (iii) oscillations of 1.4°C/min, with the temperature rapidly falling until reaching 1.3°C (T0R) and (iv) oscillations of 1.1°C/min, with the temperature slowly falling until reaching 4.2°C (T0S). The results revealed that after 30 min, UV10 and UV20 sperm samples showed significantly (p < .05) lower total and progressive motility values, sperm kinematic parameters and mitochondrial potential. After 45 min of exposure, differences were highly significant (p < .001). No significant differences (p > .05) were found for pipetting or thermal oscillations. The results suggest that, even if equine sperm samples are not handled in the laboratory under optimal conditions, fresh and cooled equine spermatozoa are able to resist the impact of various abiotic stimuli without any reduction in their quality. This study analyses the effect on normospermic samples, but future research could look at the tolerance that asthenozoospermic equine samples have to these abiotic influences.

Morphological, ultrastructural and functional imaging of frozen/thawed and vitrified/warmed human ovarian tissue retrieved from oncological patients

STUDY QUESTION

Which is the best method for human ovarian tissue cryopreservation: slow freezing/rapid thawing (SF/RT) or vitrification/warming (V/W)?

SUMMARY ANSWER

The conventional SF/RT protocol used in this study seems to better preserve the morpho-functional status of human cryopreserved ovarian tissue than the used open carrier V/W protocol.

WHAT IS KNOWN ALREADY

Cryopreservation of human ovarian tissue is generally performed using the SF/RT method. However, reduction in the follicular pool and stroma damage are often observed. An emerging alternative procedure is represented by V/W which seems to allow the maintenance of the morphological integrity of the stroma.

STUDY DESIGN, SIZE, DURATION

This is a retrospective cohort study including six patients affected by oncological diseases and enrolled from January to December 2014.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Ovarian tissue was laparoscopically harvested from the right and left ovaries and was cryopreserved using a routinary SF/RT protocol or a V/W method, involving tissue incubation in two solutions (containing propylene glycol, ethylene glycol and sucrose at different concentrations) and vitrification in an open system. For each patient, three pieces from each ovary were collected at the time of laparoscopy (fresh tissue) and after storage (SF/RT or V/W) and processed for light microscopy (LM) and transmission electron microscopy (TEM), to assess the morphological and ultrastructural features of follicles and stroma, and for laser scanning confocal microscopy (LSCM), to determine the functional energetic/redox stroma status. The preservation status of SF/RT and V/W ovarian tissues was compared with that of fresh ones, as well as between them.

MAIN RESULTS AND THE ROLE OF CHANCE

By LM and TEM, SF/RT and V/W samples showed cryodamage of small entity. Interstitial oedema and increased stromal cell vacuolization and chromatin clumping were observed in SF/RT samples; in contrast, V/W samples showed oocyte nuclei with slightly thickened chromatin and irregular shapes. The functional imaging analysis by LSCM revealed that the mitochondrial activity and intracellular reactive oxygen species levels were reduced both in SF/RT and in V/W samples compared with fresh samples. The study also showed progressive dysfunction of the mitochondrial activity going from the outer to the inner serial section of the ovarian cortex. The reduction of mitochondrial activity of V/W samples compared with fresh samples was significantly higher in the inner section than in the outer section.

LIMITATIONS, REASONS FOR CAUTION

The results report the bioenergetic and oxidative status assessment of fresh and cryopreserved human ovarian tissue by LSCM, a technique recently applied to tissue samples. The use of LSCM on human ovarian tissues after SF/RT or V/W is a new application that requires validation. The procedures for mitochondrial staining with functional probes and fixing are not yet standardized. Xenografting of the cryopreserved ovarian tissue in severe combined immunodeficient mice and in vitro culture have not yet been performed.

WIDER IMPLICATIONS OF THE FINDINGS

The identification of a cryopreservation method able to maintain the morpho-functional integrity of the ovarian tissue and a number of follicles comparable with those observed in fresh tissue might optimize results in clinical practice, in terms of recovery, duration of ovarian function and increased delivery outcomes after replanting. The SF/RT protocol allowed better morpho-functional tissue integrity than the V/W procedure.

STUDY FUNDING/COMPETING INTERESTS

Funding was provided by Fondazione del Monte di Bologna e Ravenna, Italy. Dr N.A.M. was granted by the project ONEV MIUR PONa3 00134-n.254/R&C 18 5 2011 and the project GR-2011-02351396 (Ministry of Health, Young Researchers Grant 2011/2012). There are no competing interests.

TRIAL REGISTRATION NUMBER

Clinical trial 74/2001/0 (approved:13 2 2002): 'Pilot study on cryopreservation of human ovarian tissue: morphological and immunohistochemical analysis before and after cryopreservation'.

Centrifugation stress reduces the responsiveness of spermatozoa to a capacitation stimulus in in vitro-aged semen

Density gradient centrifugation of semen is commonly used in many assisted reproduction techniques. Although gradients have the potential to isolate and enrich motile and viable spermatozoa, the centrifugation force presents a stress factor to cell organelles and membranes. The objective of the study was to evaluate the impact of density gradient centrifugation stress on sperm capacitation dynamics, cell stability and the ability of spermatozoa to specifically respond to bicarbonate in extended semen undergoing in vitro ageing. Extended boar semen (n = 7) was stored for 12, 24, 72 and 120 h respectively at 17 °C before centrifugation and incubation in variations of an in vitro capacitation medium. The number of viable, acrosome intact sperm and motility parameters as assessed by computer-assisted semen analysis did not change during storage. Kinetic changes in viability (plasma membrane integrity) and intracellular calcium levels (calcium influx) during in vitro capacitation were assessed after preparation of semen samples with both, a Percoll and a sucrose gradient centrifugation, either only Percoll, only sucrose centrifugation or no centrifugation. Changes in the viable sperm population that could be specifically attributed as a response to either bicarbonate or calcium were determined. In in vitro-aged (>12 h stored) spermatozoa, centrifugation reduced the proportion of spermatozoa which specifically responded to the capacitating stimulus bicarbonate. Concomitantly, centrifugation increased the proportion of spermatozoa responding to calcium in absence of bicarbonate, thus indicating an increased sensitivity to incubation per se. Absence of centrifugation steps during semen preparation, revealed a highly conserved ability of in vitro-aged spermatozoa to specifically respond to bicarbonate. In conclusion, density gradient centrifugation alters the physiological property of spermatozoa for controlled capacitation, which may influence the success rates of centrifuged semen in assisted reproductive technologies and confound interpretation of capacitation assays.

Do photoperiod and endocrine disruptor 4-tert-octylphenol effect on spermatozoa of bank vole (Clethrionomys glareolus)?

Photoperiod is an environmental signal that controls physiology and behavior of all organisms. Bank voles, which are seasonal breeders, are stimulated to reproduce by the long photoperiod associated with spring and summer. To date, physiology of bank vole spermatozoa has not been explored, although they constitute an interesting model for examining the relationship between photoperiod and xenoestrogen on spermatozoa function. In an attempt to evaluate the acute effect of 4-tert-octylphenol (OP) an in vitro system was used. Spermatozoa isolated from the cauda epididymidies of long-day (LD; 18 h light: 6 h darkness) and short-day (SD; 6 h light: 18 h darkness) bank voles were treated with two OP concentrations (10(-4) M and 10(-8)M, respectively). OP-treated spermatozoa were used for the examination of motility parameters (computer-assisted semen analyzer CEROS), acrosome integrity (Commassie blue staining), cAMP production (immunoenzymatic assay) and cell viability (flow-cytometry analysis). The study revealed the photoperiod-dependent effect of short OP-treatment on motility parameters of vole spermatozoa. In LD spermatozoa, an increase of velocities: (curvilinear velocity [VCL], average path velocity [VAP] straight line velocity [VSL]) and head activity (amplitude of the lateral head displacement, [ALH]) was found. Interestingly, in SD spermatozoa opposite effect on VCL, VAP, VSL and ALH was observed, however only after treatment with 10(-4)M OP. The dose-dependent influence of OP upon acrosome integrity, as well as cAMP levels, in relation to the reproductive status of voles was observed. Moreover, OP exposure affected spermatozoa morphology rather than spermatozoa viability.

Sensibility of male rats fertility against olive oil, Nigella sativa oil and pomegranate extract

OBJECTIVE

To clarify the modulatory effects of daily consumption of pomegranate extract (PE), olive oil (OO) and Nagilla sativa oil (NSO) on antioxidant activity, sperm quality and pituitary-testicular axis of adult male wistar rats.

METHODS

Thirty-two adult male Wistar rats were divided into four equal groups, eight rats each. Using rat gastric tubes, 1.0 mL distilled water, 1.0 mL PE, 0.4 mL NSO and 0.4 mL OO were orally administered daily for 6 weeks in the first, second, third and fourth groups, respectively. Reproductive organs, body weight, sperm criteria, testosterone, FSH, LH, inhibin-B, lipid peroxidation, and antioxidant enzyme activities were investigated. At the end of the study protocol, analyses occurred at the same time. Data were analysed by ANOVA test and P<0.05 was considered to be a significant value.

RESULTS

In all studied groups, malondialdehyde level was significantly decreased accompanied with an increases in glutathione peroxidase and glutathione. Rats treated with PE showed an increase in catalase activities accompanied with an increase in sperm concentration which was also observed in NSO group. In PE treated group, sperm motility was also increased accompanied with decreased abnormal sperm rate. NSO, OO and PE treated groups shows an insignificant effect on testosterone, inhibin-B, FSH and LH in comparison with control group.

CONCLUSIONS

These results show that administration of PE, NSO and OO could modify sperm characteristics and antioxidant activity of adult male wistar rats.