Antioxidants protect proteins' anchorage to the bilayer by improving plasma membrane integrity of ram spermatozoa during liquid preservation in a soya lecithin-based diluent

Purification and partial characterization of a sperm motility-inhibitory protein of ram cauda epididymal plasma

Mammalian sperm remain quiescent but fertile for several weeks in cauda epididymis. Although several sperm quiescent factors of epididymal plasma have been identified in goat, pig and cattle; however, little is known in sheep. In the present study, purification and characterization of a novel sperm quiescent protein of ovine cauda epididymal plasma (CEP) was carried out. The sperm quiescent protein was partially purified by hydroxyapatite gel adsorption chromatography followed by DEAE-sepharose® anion exchange chromatography. In the latter, the sperm quiescent activity was eluted both in 0.05 and 0.2 M potassium phosphate buffer (pH 7.5) fractions having a predominant protein of about 80 and 70 kDa with 87% and 63% homogeneity, respectively. The proteins were designated as motility-inhibitory factor of sheep I and II (MIFS-I and II), respectively. Significant (about 60%) inhibition of sperm motility was observed following treatment of cauda epididymal sperm with 6 and 12 µg/mL of partially purified MIFS-I and II, respectively. Specific activities of the partially purified MIFS-I and II were 563 and 261 U/mg of protein, while the fold-purification of the activity were 5119 and 2373, respectively. Both the proteins were heat-labile and the activity was completely lost following incubation at 100°C for 5 min. Further, the partially purified MIFS-I (5 µg/mL) caused significant reduction in in vitro sperm capacitation and slight decline in tyrosine phosphorylated p72 and p52 proteins; however the protein was nontoxic to sperm. Mass spectrometric analysis of MIFS-I revealed significant identity with human semaphorin 3D. Both dot blot and western blot analysis demonstrated cross-reactivity of MIFS-I with polyclonal anti-human SEMA3D antibody. It was concluded that the MIFS-I of ovine CEP was putative ovine semaphorin 3D protein having potent sperm quiescent and decapacitating activities and it possibly acts through inhibition of protein tyrosine phosphorylation.

Decoding the biological toxicity of phenanthrene on intestinal cells of Eisenia fetida: Effects, toxicity pathways and corresponding mechanisms

Phenanthrene is frequently detected and exists extensively in the soil environment, and its residues inevitably impose a significant threat to soil organisms. Exposure to and toxicity of phenanthrene on earthworms has been extensively studied before, however, the possible mechanisms and related pathways associated with phenanthrene-triggered toxicity at the intestinal cell level remain unclear. Herein, primary intestinal cells isolated from Eisenia fetida (Annelida, Oligochaeta) intestine were used as targeted receptors to probe the molecular mechanisms involved in ROS-mediated damaging effects and the potential pathways of phenanthrene-induced toxicity at cellular and sub-cellular levels. Results indicated that phenanthrene exposure induced oxidative stress by activating intracellular ROS (elevated O2-, H2O2, and OH- content) bursts in E. fetida intestinal cells, causing various oxidative damage effects, including lipid peroxidation (increased MDA content), protein oxidation (enhanced PCO levels), and DNA damage (enhanced 8-OHdG levels). The enzymatic and non-enzymatic strategies in earthworm cells were activated to mitigate these detrimental effects by regulating ROS-mediated pathways involving defense regulation. Also, phenanthrene stress destroyed the cell membrane of E. fetida intestinal cells, resulting in cellular calcium homeostasis disruption and cellular energetic alteration, ultimately causing cytotoxicity and cell apoptosis/death. More importantly, the mitochondrial dysfunction in E. fetida cells was induced by phenanthrene-caused mitochondrial membrane depolarization, which in turn caused un-controlled ROS burst and induced apoptosis through mitochondria-mediated caspase-3 activation and ROS-mediated mitochondrial-dependent pathway. Furthermore, exposure to phenanthrene activated an abnormal mRNA expression profile associated with defense regulation (e.g., Hsp70, MT, CRT, SOD, CAT, and GST genes) in E. fetida intestinal cells, resulting in various cellular dysfunctions and pathological conditions, eventually, apoptotic cell death. Taken together, this study offers valuable insights for probing the toxic effects and underlying mechanisms posed by phenanthrene at the intestinal cell level, and is of great significance to estimate the detrimental side effects of phenanthrene on soil ecological health.

Recent approaches in the use of antioxidants and proteomic modifications in ram semen preservation

Sperm preservation is a well-established technique in reproductive biotechnology that is widely used to maintain the genetic quality of male individuals. However, there are several factors during the preservation process that can affect the vitality, functionality, and quality of sperm, thereby reducing their fertility potential after thawing. One of these factors is the synthesis of high levels of oxidative stress (OS) during semen preservation, which can have detrimental effects on sperm health and functionality. To counter the negative impact of OS on sperm, researchers have explored the supplementation of several exogenous antioxidants in the extenders used to preserve ram sperm. This approach has shown promising results in improving sperm health, functionality, and fertility potential in ram. Additionally, the preservation process can induce modifications in the ram sperm proteome. By employing targeted proteomics techniques, researchers have been able to identify and modify specific proteins in cryopreserved ram sperm, potentially offering further improvements in the quality of the cryopreserved ram sperm. In summary, this review provides a comprehensive overview of the antioxidants and targeted proteomics modifications that have been investigated for enhancing ram sperm preservation. These advancements aim to mitigate the negative effects of OS and optimize the techniques used in preserving ram sperm.

The enriched Y-bearing sperm combined with delayed fixed-time artificial insemination for obtaining male Simmental crossbred offspring

Background and Aim:

The production of male calf beef cattle is an agricultural innovation needed to increase the farm’s productivity as a provider of meat sources. This study aimed to determine the sex ratio of the offspring of cows inseminated with Y-bearing sperm enriched by Percoll density gradient centrifugation and swim-up, combined with delayed fixed-time artificial insemination (FTAI).

Materials and Methods:

Ejaculates of Simmental bulls were divided into four equal portions and grouped as T0 (control, non-sexed semen), T1 and T2 were sexed semen using Percoll density gradient centrifugation three and five levels, respectively, and T3 was sexed semen using swim-up. After the sex was sorted, the semen was diluted in a tris-egg yolk extender, packaged in French mini-straws containing 50 million live sperm cells, and frozen. Pre-sexed, post-sexed, and post-thawed spermatozoa were evaluated based on progressive motility, viability, intact plasma membrane, and abnormality. The post-thawed semen of T0 was artificially inseminated to recipient cows at 12 h after onset of estrus (not delayed FTAI). Meanwhile, the delayed FTAI was conducted 18-20 h after onset of estrus using the T0, the best of T1 and T2, and the T3 post-thawed semen.

Results:

The Percoll density gradient centrifugation reduced motility, viability, and intact plasma membrane but increased sperm abnormalities. Meanwhile, the swim-up process increased motility, viability, and intact plasma membrane of sperm cells but decreased sperm abnormalities. Post-thawed semen decreased motility, viability, and intact plasma membrane of sperm cells but increased sperm abnormalities. The sex ratio of the Simmental crossbred offspring was 96.08% and 100% in T1 and T3, respectively, compared to 48.25% and 67.39% in T0 not delayed and delayed FTAI, respectively.

Conclusion:

The Percoll density gradient centrifugation and swim-up methods are prospective for obtaining male offspring.

Role of Antioxidants in Cooled Liquid Storage of Mammal Spermatozoa

Cooled preservation of semen is usually associated with artificial insemination and genetic improvement programs in livestock species. Several studies have reported an increase in reactive oxidative species and a decrease in antioxidant substances and sperm quality parameters during long-term semen storage at refrigerated temperatures. The supplementation of antioxidants in extenders before refrigeration could reduce this detrimental effect. Various antioxidants have been tested, both enzymatic, such as superoxide dismutase and catalase, and non-enzymatic, such as reduced glutathione, vitamins E and C and melatonin. However, the problem of oxidative stress in semen storage has not been fully resolved. The effects of antioxidants for semen-cooled storage have not been reviewed in depth. Therefore, the objective of the present study was to review the efficiency of the supplementation of antioxidants in the extender during cooled storage of semen in livestock species.

Pre-freezing equilibration for 22 h improves post-thaw sperm functions in cryopreserved ram semen by reducing cholesterol efflux

Failure of cervical insemination with cryopreserved semen is hindering implementation of AI in sheep in field condition. Here the effect of equilibration time and catalase on post-thaw qualities of ram semen was investigated. Pooled semen was diluted (800 × 10⁶ sperm mL^-1) with a TES-Tris-fructose extender with 6% glycerol, 15% egg yolk and supplemented with 0, 50, 100 and 200 U mL^-1 catalase and packaged into 0.25 mL straws. In experiment 1, straws were equilibrated at 5 °C either for 3 h in a cold cabinet (E3) or for 10 (E10) and 22 h (E22) inside a refrigerator. In experiment 2, all straws were equilibrated for 22 h inside refrigerator. Straws were frozen at -25 °C min^-1 up to -125 °C using a cell freezer and finally plunged into liquid nitrogen. The post-thaw total and rapid motility were higher (P < 0.05) in E22 compared to E3 and E10. Sperm kinetics was comparable between E3 and E22, but lower in E10. Similarly, acrosome integrity, functional membrane integrity, percent high cholesterol (mCHO) and live-high mitochondrial membrane potential (MMP) were higher (P < 0.05) while live-high intracellular calcium and acrosome-reacted sperm were lower in E22 compared to E3 and E10. The percent rapid motile, high mCHO and live-high MMP were significantly (P < 0.05) lower in catalase-treated samples compared to the control, while the membrane integrity was comparable within the groups. In conclusion, pre-freezing equilibration for 22 h compared to 3 or 10 h resulted in higher post-thaw sperm functions while catalase had negative impact on cryopreservation of ram semen.

Mimicking the cauda epididymal plasma-like osmolality in extender improves liquid preservation of ram semen at 3-5°C

Cauda epididymis in mammals is known to store mature sperm largely in quiescent state for several weeks without significantly affecting fertility. Hence, the aim of this study was to evaluate the effects of mimicking cauda epididymal plasma (CEP)-like conditions in extender on liquid preservation of ram semen at 3-5°C. Four experiments were conducted in this study: (1) evaluation of physicochemical properties of ram CEP, (2) effect of hyperosmotic solution on sperm motility and functional membrane integrity (FMI), and the effects of (3) CEP-like hyperosmolality (390 vs. 360 mOsmol/kg) and (4) pH in extender (pH 6.5 vs. 6.8) on liquid preservation of ram semen. Sperm treatment with hyperosmotic solution (450 mOsmol/kg) resulted in a decline (P < 0.05) in mass motility (3.5 ± 0.2 vs. 4.3 ± 0.2) and FMI (30.4 ± 3.2 vs. 52.1 ± 2.1%) compared to that with isoosmotic solution (360 mOsmol/kg). Overall, sperm viability, acrosomal integrity, and progressive motility were similar (P > 0.05) while straight-line velocity (77.8 ± 3.1 vs. 71.3 ± 2.7µm/s), linearity (47.4 ± 0.4 vs. 39.5 ± 0.9%), straightness (79.7 ± 0.5 vs. 74.0 ± 0.5%) and beat cross frequency (28.6 ± 0.8 vs. 26.0 ± 0.5 Hz) were higher (P < 0.05) and FMI (65.7 ± 1.5 vs. 75.4 ± 1.1%) was lower (P < 0.05) following liquid-preservation in hyperosmotic extender compared to that in isoosmotic extender. Both total motility (83.3 ± 1.8 vs. 75.4 ± 1.5%) and progressive motility (51.7 ± 2.3 vs. 39.5 ± 1.9%) were higher (P < 0.05) at 48 h of storage in hyperosmotic extender compared to the control. Overall, the seminal attributes were similar (P > 0.05) between the two pH's of the extender. In conclusion, semen extender having CEP-like osmolality but not the pH was superior to extenders having conventional osmolality and pH for liquid preservation of ram semen.Abbreviations: AI: artificial insemination; ALH: amplitude of lateral head displacement; BCF: beat cross frequency; CASA: computer-assisted semen analyzer; CEP: cauda epididymal plasma; ELON: elongation; EYTF: egg yolk-Tris-citrate-fructose; FMI: functional membrane integrity; GLM: general linear model; GPC: glycerophosphatidylcholine; HOS: hypoosmotic swelling; LIN: linearity; pHe: external pH; PROG: progressive motility; S.E.M.: standard error of the mean; SLTF: soya lecithin-Tris-fructose extender; SP: seminal plasma; STR: straightness; VAP: average path velocity; VCL: curvilinear velocity; VSL: straight-line velocity; TM: total motility.