Dimethylsulfoxide, methanol and methylglycol in the seminal cryopreservation of Suruvi, Steindachneridion scriptum

Dimethyl acetamide and dimethyl sulfoxide associated at glucose and egg yolk for cryopreservation of Pseudoplatystoma corruscans semen

Abstract This study aimed to develop a protocol for the cryopreservation of Pseudoplatystoma corruscans semen. For this, mature males were hormonally induced with a single dose of carp pituitary extract (5 mg/kg body weight). Semen was collected and evaluated. Two cryoprotectants were tested to compose the diluents: dimethyl acetamide (DMA) and dimethyl sulfoxide (Me2SO), in two concentrations (8% and 10%), + 5.0% glucose + 10% egg yolk. The semen was diluted in a 1: 4 ratio (semen: extender), packed in 0.5 mL straws and frozen in a dry shipper container in liquid nitrogen vapors. After thawing, sperm kinetics, sperm morphology and DNA integrity of cryopreserved sperm were evaluated. Pseudoplatystoma corruscans males produced semen with sperm motility > 80%. After thawing, all treatments provided semen with total sperm motility > 40%, with no significant difference (P < 0.05) between them, as well as between the other sperm kinetic parameters evaluated. The treatments with DMA provided a smaller fragmentation of the DNA of the gametes. Sperm malformations were identified in both fresh and cryopreserved semen, with a slight increase in these malformations being identified in sperm from thawed P. corruscans semen samples.

Sperm characterization and cryopreservation of the endangered freshwater fish Chirostoma estor (Atheriniformes)

The knowledge of the physiology of sperm of an endangered species allows the implantation of reproductive biotechnologies that aim at conservation. The aim of this study was to characterize fresh sperm and evaluate different cryopreservation solutions for sperm in Chirostoma estor. The characterization of Chirostoma estor fresh sperm (n = 22 males) was performed through analyzes of sperm concentration, membrane integrity, sperm morphology, motility rate, motility quality score, and motility duration. For cryopreservation (n = 42 males), 3 extenders (BTS™, MIII™, or Androstar Plus™) in combination with 2 permeable cryoprotectants (dimethyl sulfoxide (DMSO) or methyl glycol (Methyl)) were used. Analyzes of post-thaw sperm were performed as described for fresh sperm and additionally the fertilization rate analysis was performed. Fresh sperm presented a sperm concentration of 29.2 × 10⁹ spermatozoa/mL, membrane integrity of 82.4%, and morphologically normal cells of 53%. After glucose activation (150 mM) a motility rate of 87.5%, sperm quality score of 5.0, and a duration of motility of 285 s were observed. For post-thaw sperm, MIII + Methyl and Androstar + Methyl solutions resulted in the highest motility rates of 40-48%. No differences were observed for motility duration, membrane integrity, and sperm morphology. Samples cryopreserved in Methyl (12-20%) showed a higher fertilization rate than DMSO, independently of the extender. In conclusion, the fresh sperm collected artificially from Chirostoma estor presents a compatible quality to carry out fertilization and can be cryopreserved in the commercial extenders MIII™ and Androstar Plus™ together with the cryoprotectant Methyl glycol.

Relationship between bovine oocytes developmental competence and mRNA expression of apoptotic and mitochondrial genes following the change of vitrification temperatures and cryoprotectant concentrations

The present study analyzed the relationship between bovine oocytes developmental competence and mRNA expression of apoptotic and mitochondrial genes following the change of vitrification temperatures (VTs) and cryoprotectant agent concentrations (CPAs). Cumulus oocyte complexes were randomly divided into five groups: control, vitrified in liquid nitrogen (LN; -196 °C) with 5.6 M CPAs (LN 5.6 M), LN with 6.6 M CPAs (LN 6.6 M), liquid helium (LHe; -269 °C) with 5.6 M CPAs (LHe 5.6 M), and LHe with 6.6 M CPAs (LHe 6.6 M). After vitrification and warming, oocytes of vitrified and control groups were subjected to in vitro maturation (IVM), in vitro fertilization and in vitro culture. The blastocyst rate in LHe 5.6 M group was the highest among the four vitrified groups (13.7% vs. 9.4%, 1.3%, and 8.4%; P < 0.05). The mRNA expression level of 8 apoptotic- and 12 mitochondria-related genes were detected through qRT-PCR after IVM. Lower VT (LHe, -269 °C) positively affected the mRNA expression levels of apoptotic genes (BAD, BID, BTK, TP53, and TP53I3) and mitochondrial genes (COX6B1, DERA, FIS1, NDUFA1, NDUFA4, PRDX2, SLC25A5, TFB1M, and UQCRB), and reduced oxidative stress from freezing. Decreased CPAs (5.6 M) positively affected mRNA expression levels of apoptotic genes (BAD, BCL2A1, BID, and CASP3) in LHe vitrification but negatively affected apoptotic genes (BAD, BAX, BID, BTK, and BCL2A1) in LN vitrification. In conclusion, decreased VTs and CPAs in LHe vitrification may increase the blastocyst rate by changing the mRNA expression levels of these apoptotic and mitochondrial genes for the vitrified oocytes.

Impacts of the biocide chlorothalonil on biomarkers of oxidative stress, genotoxicity, and sperm quality in guppy Poecilia vivipara

Chlorothalonil is a fungicide present in antifouling paints and other formulations used in agriculture, although studies have shown this chemical to be toxic to fish species. To clarify the deleterious effects of chlorothalonil for these non-target organisms, the present study evaluated the toxic effects of this biocide for the estuarine guppy Poecilia vivipara in terms of an acute mortality test (96 h) and the analysis of biomarkers of oxidative stress, genotoxicity, and sperm quality. The LC₅₀ calculated for P. vivipara was 40.8 μg/L of chlorothalonil. For the analysis of biomarkers, fish were exposed (96 h) to 1 and 10 μg/L of chlorothalonil. It was observed that chlorothalonil alters the levels of pro- and antioxidants towards oxidative stress. In the gills, a negative effect on total antioxidant capacity (ACAP) was detected, while there was a reduction in the activity of glutathione S-transferase (GST) in the liver. However, levels of glutathione (GSH) and the activity and glutamate-cysteine-ligase (GCL) increased in both tissues, as a possible detoxification response. Following chlorothalonil exposure, oxidative damage measured by lipoperoxidation (LPO) significantly increased at the cellular level only (red blood cells (RBCs) and sperm cells). An increase in fluidity of membranes, reactive oxygen species concentration and micronuclei (MNs) incidence were also seen in RBCs. In sperm cells, LPO increased, while membrane and mitochondrial functionality as well as sperm motility decreased. Based on these results, chlorothalonil can be considered as a toxic compound for fish, causing genotoxicity and affecting the RBCs physiology and the fertility of males of P. vivipara.

Seminal characteristics and sensitivity of Astyanax lacustris (Characiformes: Characidae) sperm to cryoprotective solutions based on dimethylsufoxide and methylglicol

Abstract This study aimed to determine the semen characteristics of Astyanax lacustris after hormonal induction and to evaluate the sensitivity of the species sperm to cryoprotective solutions based on the cryoprotectants dimethyl sulfoxide and methyl glycol. Volume, color, sperm concentration, total motility and aspects of sperm movement were analyzed using “Integrated Semen Analysis System”. Three different extenders were tested: A) glucose 5%+egg yolk 10%, B) BTS®5% and C) glucose 5% and two permeable cryoprotectants: dimethyl sulfoxide (Me2SO) and methyl glycol (MTG). Fresh A. lacustris semen presented total motility of 76.6±11.2%, motility duration of 33.0±2.2s, sperm concentration of 7.22±3.2×109sptz/mL and seminal osmolality of 219±0.03mOsm/kg-1. The toxicity test showed the highest total motility values at the MTG15%+A, Me2SO15%+B and Me2SO10%+C dilutions, and the Me2SO10%+C and Me2SO15%+C dilutions presented the highest values for curvilinear velocity, linear velocity and average velocity. The tested protocol was not effective at maintaining the viability of A. lacustris semen after freezing because no motility was observed in any of the dilutions. However, the Comet Assay demonstrated that cryoprotectant solutions were effective in protecting the genetic material of cells, as DNA damage levels were low, with no difference between control and Me2SO10% + A, dilutions MTG10%+C, Me2SO10%+B and Me2SO15%+B.

Effects of cryopreservation on cAMP-dependent protein kinase and AMP-activated protein kinase in Atlantic salmon (Salmo salar) spermatozoa: Relation with post-thaw motility

Sperm motility in fish with external fertilization is critical for reproductive efficiency in aquaculture, especially in salmonids. Gamete preservation techniques, such as cryopreservation, however, reduce sperm motility and fertilizing capacity. Very few studies have addressed cryodamage from energetic and cell signalling approaches. In this study, cAMP-dependent protein kinase (PKA) and AMP-activated kinase (AMPK) activities were quantified in fresh and cryopreserved spermatozoa of Atlantic salmon (Salmo salar); and the relation with motility was analysed. Results indicate there was a decrease in membrane integrity and motility in post-thawed spermatozoa compared to fresh samples, however, there was about 30% of cells with intact plasma membrane but incapable of motility. The PKA and AMPK activities were less after cryopreservation, indicating that loss of motility may be related to alteration of these key enzymes. Furthermore, PKA and AMPK activities were positively correlated with each other and with motility; and inhibition decreased motility, indicating there is a functional relationship between PKA and AMPK. The PKA inhibition also decreased AMPK activity, but results from protein-protein docking analyses indicated AMPK activation directly by PKA is unlikely, thus an indirect mechanism may exist. There have been no previous reports of these kinase actions in fish spermatozoa, making these findings worthy of assessment when there are future studies being planned, and may serve as base knowledge for optimization of cryopreservation procedures and development of biotechnologies to improve reproduction efficiency in the aquaculture industry.