Differences in semen freezability and intracellular ATP content between the rooster (Gallus gallus domesticus) and the Barbary partridge (Alectoris barbara)

Effects of resveratrol on DLD and NDUFB9 decrease in frozen semen of Mongolian sheep

Mongolian sheep are a breed of sheep in China known for their excellent cold and drought resistance. Sperm from Mongolian sheep are often cryopreserved to improve breeding outcomes. However, cryopreservation of sperm often results in issues such as reduced vitality and altered morphology. Therefore, the objective of this study was to investigate the impact of the cryoprotectant resveratrol on frozen sperm from Mongolian sheep, specifically examining its effects on key proteins during cryopreservation. In this study, sperm samples were obtained from three adult Mongolian rams and processed through semen centrifugation. The sperm motility parameters of Fresh Sperm Group (FR), Resveratrol added before freezing group (FF-Res), Resveratrol-free frozen sperm group (FT), and Resveratrol added after freeze-thawing group (FA-Res) were determined. The tandem mass tags (TMT) peptide labeling combined with LC-MS/MS was used for proteomic analysis of the total proteins in FR and FT groups. A total of 2651 proteins were identified, among which 41 proteins were upregulated and 48 proteins were downregulated after freezing. In-depth bioinformatics analysis of differentially abundant proteins (DAPs) revealed their close association with the tricarboxylic acid cycle (TCA) and oxidative phosphorylation pathway. The energy-related protein dihydrolipoamide dehydrogenase (DLD) and the reactive oxygen species (ROS)-related protein NADH dehydrogenase 1 beta subcomplex subunit 9 (NDUFB9) exhibited significant decreases, indicating their potential role as key proteins contributing to reduced sperm vitality. The study demonstrated that the addition of resveratrol (RES) to semen could elevate the expression levels of DLD and NDUFB9 proteins. This study represents the pioneering proteomic analysis of Mongolian ram sperm before and after cryopreservation, establishing the significance of DLD and NDUFB9 as key proteins influencing the decline in vitality following cryopreservation of Mongolian ram sperm. These findings clarify that resveratrol can enhance the levels of DLD and NDUFB9 proteins in cryopreserved Mongolian ram sperm, consequently enhancing their vitality.

Collection, Handling, and Preservation of Wild Bird Semen: Current Status, Challenges, and Perspectives

Semen preservation is a significant biotechnology used to safeguard the genetic material of birds, especially those with declining populations, through biobanking. However, there are limited reports on the successful chilling or cryopreservation of wild bird semen. In general, these techniques are not yet well-established for several species of wild birds and pose several challenges such as the need for bird handling and training, contamination of semen samples, low volume of semen collected, and inefficient preservation protocols. To address these challenges and improve post-thawing outcomes, new possibilities are being investigated, including alternative collection methods to traditional digital massage, the use of antioxidants and enzymes in the medium for chilling or freezing, storage methods using different straws from the usual pellet, and slower freezing rates. This review aims to discuss the various aspects of applying semen preservation in wild birds to create germplasm banks, highlighting the primary results obtained and the challenges that need to be addressed.

Effect of Dimethylacetamide Concentration on Motility, Quality, Antioxidant Biomarkers, Anti-Freeze Gene Expression, and Fertilizing Ability of Frozen/Thawed Rooster Sperm

Sperm cryopreservation is of great importance for the poultry industry but still needs to be optimized. The high susceptibility of poultry sperm to cryodamage leads to low fertility rates after cryopreservation. Therefore, the present study aimed at evaluating the effect of including a cryoprotectant, dimethylacetamide (DMA), in the chicken semen freezing extenders at a final concentration of 3%, 6%, or 9% on the post-thawed sperm motility, quality, antioxidant biomarkers, anti-freeze gene expression, and fertilizing ability. Results showed that the total motile sperm, progressivity, and viability were quadratically increased (p < 0.05) in the 6% DMA group. The antioxidant enzyme activity and lipid peroxidation were negatively (p < 0.05) affected by the increase in DMA concentration. Furthermore, some anti-freeze-associated genes such as heat shock protein 70 (HSP70) and ras homolog family member A (RHOA) were linearly and quadratically down-regulated (p < 0.05) with the high concentration of DMA. Finally, the fertility and hatchability rates did not indicate statistical differences between DMA groups. It can be concluded that using the low concentration of 3−6% DMA in the freezing semen extender is preferable to obtain acceptable results in the post-thawed sperm quality and fertility.

Application of the comet assay for the evaluation of DNA damage in mature sperm

DNA integrity is considered an important parameter of semen quality and is of significant value as a predictor of male fertility. Currently, there are several methods that can assess sperm DNA integrity. One such assay is the comet assay, or single-cell gel electrophoresis, which is a simple, sensitive, reliable, quick and low-cost technique that is used for measuring DNA strand breaks and repair at the level of individual cells. Although the comet assay is usually performed with somatic cells from different organs, the assay has the ability to detect genotoxicity in germ cells at different stages of spermatogenesis. Since the ability of sperm to remove DNA damage differs between the stages, interpretation of the results is dependent on the cells used. In this paper we give an overview on the use and applications of the comet assay on mature sperm and its ability to detect sperm DNA damage in both animals and humans. Overall, it can be concluded that the presence in sperm of significantly damaged DNA, assessed by the comet assay, is related to male infertility and seems to reduce live births. Although there is some evidence that sperm DNA damage also has a long-term impact on offspring's health, this aspect of DNA damage in sperm is understudied and deserves further attention. In summary, the comet assay can be applied as a useful tool to study effects of genotoxic exposures on sperm DNA integrity in animals and humans.

Comparative transcriptome analysis digs out genes related to antifreeze between fresh and frozen-thawed rooster sperm

The objective of this study was to investigate differences in mRNA expression between fresh and frozen–thawed sperm in roosters. In trial 1, gene expression profiles were measured using microarray with Affymetrix GeneChip Chicken Genome Arrays. The results showed that 2,115 genes were differentially expressed between the 2 groups. Among these genes, 2,086 were significantly downregulated and 29 were significantly upregulated in the frozen–thawed sperm group. Gene Ontology (GO) analysis showed that more than 1,000 differentially expressed genes (DEG) of all significantly regulated genes were involved in GO terms including biological processes, molecular function, and cellular component. Kyoto Encyclopedia of Genes and Genomes analysis showed that DEG were significantly (P < 0.05) enriched on ribosome, oxidative phosphorylation, proteasome, cell cycle, oocyte meiosis, and spliceosome pathways. In trial 2, ejaculated semen was collected from 18 roosters and divided into 5 recombinant HSP90 protein–supplemented groups (0.01, 0.1, 0.5, 1, or 2 μg/mL) and one control group with no recombinant HSP90 protein supplementation to evaluate the effect of recombinant HSP90 protein in the extender on post-thaw quality of rooster semen. The results showed that post-thaw sperm viability and motility was significantly improved (P < 0.05) in the extender containing 0.5 and 1 μg/mL of recombinant HSP90 protein compared with the control. Our preliminary results will provide a valuable basis for understanding the potential molecular mechanisms of cryodamage in frozen–thawed sperm and theoretical guidance to improve the fertility of frozen–thawed chicken sperm.

The comet assay in animal models: From bugs to whales - (Part 2 Vertebrates)

The comet assay has become one of the methods of choice for the evaluation and measurement of DNA damage. It is sensitive, quick to perform and relatively affordable for the evaluation of DNA damage and repair at the level of individual cells. The comet assay can be applied to virtually any cell type derived from different organs and tissues. Even though the comet assay is predominantly used on human cells, the application of the assay for the evaluation of DNA damage in yeast, plant and animal cells is also quite high, especially in terms of biomonitoring. The present extensive overview on the usage of the comet assay in animal models will cover both terrestrial and water environments. The first part of the review was focused on studies describing the comet assay applied in invertebrates. The second part of the review, (Part 2) will discuss the application of the comet assay in vertebrates covering cyclostomata, fishes, amphibians, reptiles, birds and mammals, in addition to chordates that are regarded as a transitional form towards vertebrates. Besides numerous vertebrate species, the assay is also performed on a range of cells, which includes blood, liver, kidney, brain, gill, bone marrow and sperm cells. These cells are readily used for the evaluation of a wide spectrum of genotoxic agents both in vitro and in vivo. Moreover, the use of vertebrate models and their role in environmental biomonitoring will also be discussed as well as the comparison of the use of the comet assay in vertebrate and human models in line with ethical principles. Although the comet assay in vertebrates is most commonly used in laboratory animals such as mice, rats and lately zebrafish, this paper will only briefly review its use regarding laboratory animal models and rather give special emphasis to the increasing usage of the assay in domestic and wildlife animals as well as in various ecotoxicological studies.

Spermatozoa DNA and plasma membrane integrity after pellet optimized processing for cryopreservation in meat type chicken breeders

1. Aim of this study was the development of an optimised cryopreservation pellet procedure for chicken semen and the assessment of DNA and membrane integrity in frozen/thawed spermatozoa in a Hubbard F15 meat type selected strain. 2. The following semen processing conditions were studied: spermatozoa working concentration (SWC), 1.5 vs 2 × 10⁹ cells/ml in pre-freezing extender; equilibration of diluted semen at 5°C, 20 vs 40 min; dimethylacetamide concentration, 6% vs 9%; dimethylacetamide equilibration time at 5°C, 1 vs 30 min; thawing at 60°C for 10 vs 50°C for 30 sec. Spermatozoa viability (EtBr exclusion procedure - stress test), mobility (Accudenz® swim-down test) and subjective motility were assessed in fresh and frozen-thawed semen. 3. The lower SWC (1.5 × 10⁹ cells/ml) and the higher dimethylacetamide concentration (9%) had positive significant effects on the recovery rate of motile (22% vs 16%) and viable spermatozoa (39 vs 34%), respectively. 4.Membrane (SYBR14-PI staining) and DNA integrity (comet assay) were assessed before and after freezing/thawing according to the optimised protocol. 5. Recovery rates of spermatozoa with undamaged plasma membrane and DNA were 41% and 76%, respectively. The distribution of spermatozoa in classes of DNA damage was also analysed and discussed. 6. It was concluded that pellet cryopreservation was a damaging process mainly for plasma membrane rather than nuclear DNA in chicken spermatozoa.

Combined effect of permeant and non-permeant cryoprotectants on the quality of frozen/thawed chicken sperm

The aim of this study was to assess the combined effect of dimethylacetamide (DMA) and two non-permeating cryoprotective agents, trehalose and sucrose, on the quality of post-thaw chicken semen. Adult Lohmann roosters (n = 27) were used. Semen was processed according to the following treatments: Lake pre-freezing extender +6% DMA (LPF, control treatment), LPF + 0.1 M trehalose (LPF-T treatment), LPF + 0.1 M sucrose (LPF-S treatment) and LPF + 0.1 M trehalose + 0.1 M sucrose (LPF-TS treatment). Semen was loaded into straws and frozen in nitrogen vapour. Sperm quality (viability, mobility and kinetic parameters) was assessed immediately after thawing (T0) and at 5 (T5), 10 (T10) and 15 min (T15) thereafter. The different cryodiluent combinations significantly affected the kinetic parameters. The presence of trehalose, alone or with sucrose, combined with DMA improved the quality of motion in cryopreserved sperm in comparison to DMA alone (LPF) and DMA with sucrose (LPF-S). In particular, the highest values in linearity (LIN) and wobble (WOB) were measured in the treatment LPF-T. The treatments significantly affected the recovery rate of progressive motile sperm that presented the best value soon after thawing in the LPF-T treatment; moreover, the presence of trehalose, alone (LPF-T) or with sucrose (LPF-TS), significantly improved the recovery rate of progressive motile sperm also at T5 and T10 compared to LPF and LPF-S. The present results show a positive synergic action of DMA and trehalose on motile function of thawed chicken sperm.

Comparison of semen variables, sperm DNA damage and sperm membrane proteins in two male layer breeder lines

Semen variables are affected by the breed and strain of chicken. The present study was undertaken to compare the semen quality in two lines of adult chickens with particular reference to sperm chromatin condensation, sperm DNA damage and sperm membrane proteins. Semen from a PD3 and White Leghorn control line was collected at 46 and 47 weeks and 55 weeks of age. The semen was evaluated for gross variables and sperm chromatin condensation by aniline blue staining. Sperm DNA damage was assessed by using the comet assay at 47 weeks of age and sperm membrane proteins were assessed at 55 weeks of age. The duration of fertility was studied by inseminating 100 million sperm once into the hens of the same line as well as another line. The eggs were collected after insemination for 15days and incubated. The eggs were candled on 18th day of incubation for observing embryonic development. The White Leghorn control line had a greater sperm concentration and lesser percentage of morphologically abnormal sperm at the different ages where assessments occurred. There was no difference in sperm chromatin condensation, DNA damage and membrane proteins between the lines. Only low molecular weight protein bands of less than 95kDa were observed in samples of both lines. The line from which semen was used had no effect on the duration over which fertility was sustained after insemination either when used in the same line or another line. Thus, from the results of the present study it may be concluded that there was a difference in gross semen variables between the lines that were studied, however, the sperm chromatin condensation, DNA damage, membrane proteins and duration over which fertility was sustained after insemination did not differ between the lines.

Trehalose and glycerol have a dose-dependent synergistic effect on the post-thawing quality of ram semen cryopreserved in a soybean lecithin-based extender

The objective of this study was to examine the interaction of different concentrations of trehalose [0 (T0), 50 (T50) or 100 (T100) mM] and glycerol [5% (G5) or 7% (G7)] on post-thawed quality of ram semen, cryopreserved in a soybean lecithin (SL)-based extender. Twenty-eight ejaculates were collected from four rams and diluted with six trehalose/glycerol combinations: T0G5, T50G5, T100G5, T0G7, T50G7, and T100G7. Sperm motility (CASA), membrane integrity (eosin/nigrosin) and functionality (HOST), abnormal forms, capacitation status (CTC), mitochondrial activity (rhodamine 123), apoptotic features (Annexin V/propidium iodide) and lipoperoxidation (malondialdehyde production) were evaluated after thawing. Extender T100G5 yielded the highest results for total and progressive motility, sperm velocity, normal morphology, functional membranes, active mitochondria and membrane integrity, with P<0.05 in general, except for T50G7 (P>0.05). The combinations T0G5, T0G7 and T100G7 yielded the lowest post-thaw quality. We could not detect significant changes in other kinematic parameters, capacitation status or lipoperoxidation. We conclude that, in our SL-based extender, a combination of 100 mM trehalose and 5% glycerol was the most adequate combination to achieving post-thawing quality in our soybean lecithin-based extender, and our results support that a synergistic effect among trehalose and glycerol exists. We suggest that other combinations could improve these results.

Melatonin protects ram spermatozoa from cryopreservation injuries in a dose-dependent manner

Cryopreservation harms spermatozoa at different levels and thus impairs their fertilizing ability. The role of melatonin in protecting spermatozoa from different kind injuries has been widely reported. Thus, this study tested whether the addition of melatonin to ram semen freezing extender could exert a protective effect and ameliorate postthawing sperm function. Melatonin was added to recommended ram extender to yield five different final concentrations: 0.001, 0.01, 0.1, 1, and 10 mm. A control group without melatonin supplementation was included. Spermatozoa viability, motility parameters, and intracellular ATP concentrations were evaluated both before and after cryopreservation, while DNA integrity and in vitro fertilizing ability were evaluated only after thawing. Obtained results showed that the concentration of 1 mm melatonin led to higher viability rates, higher percentages of total motile and progressive motile spermatozoa, higher percentages of spermatozoa with average rapid and medium velocity, higher intracellular ATP concentrations, and higher DNA integrity among semen frozen in control and melatonin-supplemented extenders (P<0.05). In addition, results obtained after the IVF test showed that at 1 mm concentration, melatonin led to a faster first embryonic division and to higher total cleavage rates compared to the other experimental groups (P<0.05). No difference in embryo output was observed among the six experimental groups. In conclusion, the addition of melatonin to ram semen freezing extender protected spermatozoa during cryopreservation in a dose-dependent manner. These results are likely to be mediated by its well-known antioxidant properties, even if a direct action of the indolamine cannot be ruled out.