Biological Features of the Avian Male Gamete and their Application to Biotechnology of Conservation

Selection of Male Donors in Local Chicken Breeds to Implement the Italian Semen Cryobank: Variability in Semen Quality, Freezability and Fertility

Native breed conservation is an important component of poultry biodiversity. The aim of this work is to describe different steps that lead to donor selection for the implementation of the Italian Semen Cryobank of Autochthonous Chicken and Turkey Breeds. The variability within and between breeds was evaluated, and the stored semen reproductive capacity was in vivo tested using artificial insemination. Semen from Bionda Piemontese, Bianca di Saluzzo and Pepoi roosters was collected and processed. Concentration, volume, sperm membrane integrity, total motile sperm, progressive motile sperm and kinetic parameters were analyzed; sperm parameters accounting for bird variability were used to select male donors. Fresh semen quality parameters measured in donor ejaculates showed significant differences between breeds; no differences were found after cryopreservation. Variability in the fertilizing ability of cryopreserved semen was found within a breed (5-16%) and between birds within a breed (BP = 3-7%; BS = 7-31%; PP = 6-22%); only sperm quality parameters measured in fresh ejaculates, not frozen/thawed, may be associated with in vivo fertility results. In conclusion, sperm concentration and progressive motility were successfully used as selection parameters to identify chicken male donors with improved sperm quality for sperm cryobanking. However, new reliable sperm markers to predict cryopreserved semen's fertilizing ability are required.

Effects of adding antioxidant nanoparticles on sperm parameters of non-human species after the freezing and thawing process: A systematic review and meta-analysis

Cryopreservation is a widely used technique to store spermatozoa for a long time. Some Published articles have identified the cryoprotective effect of nanoparticles on sperm quality after the freeze-thaw process, but others have suggested the opposite results. PubMed, ISI Web of Science, and Scopus were systematically searched in animal studies by ("sperm" OR "spermatozoa") AND ("cryopreservation" OR "cooling storage" OR "freezing" OR "thawing") AND ("nanoparticle (lecithin nanoparticle, selenium nanoparticle, zinc nanoparticle, zinc oxide nanoparticle, nanoliposome, solid lipid nanoparticle (SLN), micelle, hydrogel, nanogel, silica nanoparticle, quantum dot, dendrimer, gold (Au) nanoparticle, silver nanoparticle, nanocomposite and mesoporous)"). Among 154 publications, data on sperm quality were extracted from 11 articles. The meta-analysis results demonstrated that nanoparticles had a positive impact on sperm progressive motility (WMD= 9.72, 95 % CI: 4.70, 14.75, p < 0.0001), total motility (WMD= 6.78, 95 % CI: 0.78, 12.78, p = 0.027), viability (WMD= 14.30, 95 % CI: 9.48, 19.13, p < 0.0001) and plasma membrane integrity (WMD = 13.74, 95 % CI: 8.20, 19.29, p < 0.0001). In conclusion, our results indicated the positive effects of nanoparticles as cryoprotectant agents on post-thawed sperm motility, viability, and membrane integrity.

Triazole pesticides exposure impaired steroidogenesis associated to an increase in AHR and CAR expression in testis and altered sperm parameters in chicken

Since several decades, we observe the decline of various bird populations that could be partly linked to the agricultural intensification and the use of large amount of pesticides. Even if triazoles compounds are the most widely used fungicides, their effects on the reproductive parameters in birds are not clearly known. In the present study, we investigated the in vitro effects of 8 triazoles compounds alone (propiconazole (PP, from 0 to 10 µM), prothioconazole (PT), epoxiconazole (Epox), tetraconazole (TT), tebuconazole (TB), difenoconazole (Dif), cyproconazole (Cypro), metconazole (MC) (from 0 to 1 mM)) on the male chicken reproductive functions by using testis explants, primary Sertoli cells and sperm samples. In testis, all triazoles at the higher concentrations for 48 h inhibited lactate and testosterone secretion mostly in association with reduced expression of HSD3B and/or STAR mRNA levels. These data were also associated with increased expression of the nuclear receptors Aryl Hydrocarbon Receptor (AHR) and Constitutive Androstane Receptor (CAR) mRNA levels in testis and for all triazoles except for PP a reduction in Sertoli cell viability. When focusing on the sperm parameters, we demonstrated that most of the triazoles (MC, Epox, Dif, TB, TT and Cypro) at 0.1 or 1 mM for either 2, 12 or 24 min of exposure decreased sperm motility and velocity and increased the percentage of spermatozoa abnormal morphology. At the opposite, PP increased sperm motility in a dose dependent manner after 2 min of exposure whereas no significant effect was observed in response to PT whatever the dose and the time of exposure. Moreover, these effects were associated with an increase in the production of reactive oxygen species in spermatozoa. Taken together, most of the triazoles compounds impair testis steroidogenesis and semen parameters potentially through an increase in AHR and CAR expression and in oxidative stress, respectively.

Data Availability Statement

All the data will be available.

New approaches for long-term conservation of rooster spermatozoa

In contrast to the livestock industry, sperm cryopreservation has not yet been successfully established in the poultry industry. This is because poultry sperm cells have a unique shape and membrane fluidity, differing from those of livestock sperm. The objective of this review is to discuss the cellular and molecular characteristics of rooster spermatozoa as a cause for their generally low freezability. Furthermore, here, we discuss novel developments in the field of semen extenders, cryoprotectants, and freezing processes, all with the purpose of increasing the potential of rooster sperm cryopreservation. Currently, it is very important to improve cryopreservation of rooster sperm on a global scale for the protection of gene resources due to the incidence of epidemics such as avian influenza.

Poultry genetic heritage cryopreservation and reconstruction: advancement and future challenges

Poultry genetics resources, including commercial selected lines, indigenous breeds, and experimental lines, are now being irreversibly lost at an alarming rate due to multiple reasons, which further threats the future livelihood and academic purpose. Collections of germplasm may reduce the risk of catastrophic loss of genetic diversity by guaranteeing that a pool of genetic variability is available to ensure the reintroduction and replenishment of the genetic stocks. The setting up of biobanks for poultry is challenging because the high sensitiveness of spermatozoa to freezing–thawing process, inability to cryopreserve the egg or embryo, coupled with the females being heterogametic sex. The progress in cryobiology and biotechnologies have made possible the extension of the range of germplasm for poultry species available in cryobanks, including semen, primordial germ cells, somatic cells and gonads. In this review, we introduce the state-of-the-art technologies for avian genetic resource conservation and breed reconstruction, and discuss the potential challenges for future study and further extending of these technologies to ongoing and future conservation efforts.

Morphological Characteristics of the Sperm of the Peregrine Falcon (Falco peregrinus) during the Reproductive Season

The morphological characteristics of different sperm cells (normal, abnormal, and immature) in the peregrine falcon during the reproductive season were analysed. We also classified the main sperm defects found in semen. Semen samples were collected from mature peregrine falcons via cloacal massage and stained with Diff-Quik stain. The percentages of normal, abnormal, and immature sperm cells were determined by bright-field optical microscopy. The number of normal spermatozoa were greater at the initial stage and subsequently decreased during the middle and later stages of the reproductive season (p < 0.01). In contrast, the percentage of abnormal spermatozoa increased significantly in the middle and end stages of the reproductive season (p < 0.05), whereas the proportion of immature spermatozoa remained stable during the study. Head defects represented the greatest proportion of morphological abnormalities, followed by the defects in the tail and midpiece regions. A small percentage of multiple defects and cytoplasmic droplets were also observed in the falcon spermatozoa. The findings of this study might be important for the development of future conservation protocols for falcon sperm.

Effect of supplementation of valine to chicken extender on sperm cryoresistance and post-thaw fertilization capacity

Recent reports showed a positive correlation between frozen-thawed rooster sperm DNA integrity and the concentrations of valine in seminal plasma. The present study evaluated the effect of supplementing valine to semen extender for freezing sperm of 2 endangered local Spanish chicken breeds with different sperm cryoresistance: Red Villafranquina (VF) showing low sperm DNA integrity after cryopreservation and Quail Castellana that shows higher DNA integrity. One pool of semen per breed was obtained twice a week for 10 wk (n = 40, 20 per breed). Each pool was divided into 2 fractions. One of these fractions was frozen in presence of valine as additive in the extender (concentration 10 mmol), whereas the other was used as control. The evaluation of the samples before and after freezing-thawing included motility (CASA-Mot system), viability (propidium iodide and SYBR-14), DNA integrity (terminal deoxynucleotidyl transferase dUTP nick end labeling), and fertility rate (percentage of eggs with blastoderm development after artificial insemination). Supplementation of valine increased several motility variables of fresh semen. In VF breed, valine increased percentage of progressive motile sperm (P = 0.025), curvilinear velocity (P = 0.033), straight-line velocity (P = 0.040), and average path velocity (P = 0.033), whereas progressive motile sperm (P = 0.019), curvilinear velocity (P = 0.006), straight-line velocity (P = 0.003) and average path velocity (P = 0.004) were improved in the Quail Castellana breed. Valine addition increased the DNA integrity of cryopreserved semen (decreased post-thaw DNA fragmentation) in both breeds, with a significant effect (P = 0.002) in VF (36.3% VF-control vs 31%VF-valine). As expected, Quail Castellana cryopreserved sperm control showed higher fertility rate (34.4% ± 12.1) than VF cryopreserved sperm control (16.1% + 6.2). Supplementing valine to the freezing extender doubled (P = 0.026) the fertility rate of VF (32.6% ± 12.2) compared with the control (16.1% + 6.2). In conclusion, supplementation of valine to chicken freezing extenders shows a positive effect on DNA fragmentation and fertilizing ability of frozen-thawed sperm, with a better response in a breed considered as the lowest freezer in our conservatory.

Functional Aspects of Seminal Plasma in Bird Reproduction

This review provides an updated overview of the seminal plasma composition, and the role of metabolic and protein components on the sperm function of avian species. In addition, the implication of seminal plasma on assisted reproductive techniques of birds was discussed. The semen of birds usually has exceptionally high sperm concentration with relatively little seminal plasma, but this contributes to very fast changes in sperm metabolism and function. The biochemical characteristics and physiological roles of the various seminal plasma components in birds (carbohydrates, lipids, amino acids, hormones, and proteins) are poorly understood. Seminal plasma content of proteins has an action on most cellular functions: metabolism, immunity, oxido-reduction regulation, proteolysis, apoptosis, ion homeostasis, and antimicrobial defenses. The variable amount of many proteins is related to a different fertility capacity of poultry sperm. The role of seminal plasma on semen conservation (chilling and freezing) remains largely a matter of speculation, as both inhibitory and stimulating effects have been found. Whereas the presence of seminal plasma did not seem to affect the sperm survival after freezing-thawing, DNA fragmentation is lower in the absence of seminal plasma. The molecular basis of the influence of seminal plasma on sperm cryo-resistance was also discussed in the present review.

Seminal Plasma Proteome as an Indicator of Sperm Dysfunction and Low Sperm Motility in Chickens

Molecular mechanisms underlying sperm motility have not been fully explained, particularly in chickens. The objective was to identify seminal plasma proteins associated with chicken sperm motility by comparing the seminal plasma proteomic profile of roosters with low sperm motility (LSM, n = 4) and high sperm motility (HSM, n = 4). Using a label-free MS-based method, a total of 522 seminal plasma proteins were identified, including 386 (∼74%) previously reported and 136 novel ones. A total of 70 differentially abundant proteins were defined, including 48 more-abundant, 15 less-abundant, and seven proteins unique to the LSM group (specific proteins). Key secretory proteins like less-abundant adhesion G-protein coupled receptor G2 (ADGRG2) and more-abundant serine peptidase inhibitor Kazal-type 2 (SPINK2) in the LSM suggested that the corresponding secretory tissues played a crucial role in maintaining sperm motility. Majority (80%) of the more-abundant and five specific proteins were annotated to the cytoplasmic domain which might be a result of higher plasma membrane damage and acrosome dysfunction in LSM. Additionally, more-abundant mitochondrial proteins were detected in LSM seminal plasma associated with lower spermatozoa mitochondrial membrane potential (ΔΨm) and ATP concentrations. Further studies showed that the spermatozoa might be suffering from oxidative stress, as the amount of spermatozoa reactive oxygen species (ROS) were largely enhanced, seminal malondialdehyde (MDA) concentrations were increased, and the seminal plasma total antioxidant capacity (T-AOC) were decreased. Our study provides an additional catalogue of chicken seminal plasma proteome and supports the idea that seminal plasma could be as an indicator of spermatozoa physiology. More-abundant of acrosome, mitochondria and sperm cytoskeleton proteins in the seminal plasma could be a marker of sperm dysfunction and loss of motility. The degeneration of spermatozoa caused by the reduced seminal T-AOC and enhanced oxidative stress might be potential determinants of low sperm motility. These results could extend our understanding of sperm motility and sperm physiology regulation.

Effect of the Age and Body Weight of the Broiler Breeders Male on the Presentation of Oxidative Stress and Its Correlation with the Quality of Testicular Parenchyma and Physiological Antioxidant Levels

Chicken meat is a food of high nutritional quality; its production requires birds called broilers breeders and looking after all aspects that influence their reproductive capacity. An ongoing controversy exists among researchers related to the weight of the rooster and its fertilization capacity. By histological and biochemical tests, the association between weight and age with oxidant damage, testicular parenchyma and antioxidant capacity was evaluated in Ross 308 roosters. Testicular integrity was assessed by histological analysis, oxidative stress was determined by malondialdehyde content, non-enzymatic antioxidant capacity was determined by oxygen radical absorbance capacity assay and enzymatic antioxidant capacity through glutathione peroxidase, glutathione reductase and glutathione-S-transferase activities. Histological analysis showed vacuolization of the epithelium from the seminiferous tubules. A significant negative association was observed between malondialdehyde and the deterioration of the integrity of the seminiferous epithelium, as well as between age and integrity of the seminiferous epithelium. It became evident that oxidative damage directly affects the quality of testicular parenchyma. Weight and age were not associated with the antioxidant enzymes activities, but with non-enzymatic capacity. The data obtained suggest that weight is not the most important factor that influences the fertility of the rooster.

Optimization of Sperm Cryopreservation Protocol for Peregrine Falcon (Falco peregrinus)

Sperm cryopreservation is a complex process that needs to be adapted to wild and domestic avian species to ensure proper efficiency. Because of its accessibility, the peregrine falcon may be used as a good model for studying other raptor species. To find the most optimal cryopreservation protocol for peregrine falcon ejaculates, sperm parameters such as motility, viability, DNA fragmentation, acrosome integrity, and mitochondrial activity were analyzed under different conditions by varying the freezing method (slow freezing in straws vs. ultrarapid freezing in pellets), thawing conditions (37 °C for 30 s vs. 5 °C for 1 min), type of cryoprotectant (DMA vs. DMSO), and concentration of DMSO (4% vs. 8%). Results show that slow cryopreservation in straws yielded greater percentages (p < 0.05) of motile spermatozoa (22.5% ± 4.4% vs. 0.0% ± 4.1%), viable spermatozoa with intact acrosomes (84.6% ± 4.3% vs. 77.4% ± 4.3%), and spermatozoa with active mitochondria (41.0% ± 6.7% vs.12.8% ± 6.7%), compared with those obtained by the ultrarapid freezing in pellets. However, no differences were found between different thawing conditions. Moreover, all sperm motility parameters were greater (p < 0.05) when DMSO was used during freezing compared with DMA, although the use of 3% and 8% DMSO produced similar results. In conclusion, these results represent important progress in the study of falcon semen cryopreservation protocol, highlighting the crucial steps of the process and the most suitable conditions.

Different concentrations of cysteamine, ergothioneine, and serine modulate quality and fertilizing ability of cryopreserved chicken sperm

The aim of this study was to evaluate the effects of freezing diluents supplemented in three potential amines/amino acids, namely, antioxidant cysteamine (2-aminoethanethiol [AET]), ergothioneine (ERG), and serine (SER), in optimization of chicken sperm cryopreservation. The semen of 36 Pradu Hang Dum males, selected based on their motility vigor score, was frozen by a simple freezing method using nitrogen vapors and dimethylformamide (DMF). In a first experiment, a wide range of AET, ERG, and SER doses were tested. Semen quality was evaluated after incubation at 5°C or after cryopreservation in straws in the Blumberger Hahnen Sperma Verdünner (BHSV) diluent + DMF (6% v/v) with or without AET, ERG, or SER. The best targeted doses of AET, ERG, or SER were then selected for experiment 2 that was focused on cryopreserved semen. Frozen-thawed sperm quality was evaluated by different in vitro tests and by evaluation of fertility. Objective motility parameters were evaluated by computer-assisted sperm analysis. Membrane integrity, acrosome integrity, and mitochondria function were evaluated using appropriate dyes and flow cytometry. Lipid peroxide production was assessed by the thiobarbituric acid test (malondialdehyde production). Fertility obtained with frozen-thawed semen supplemented or not in AET, ERG, or SER was evaluated after artificial insemination of laying hens. ERG and AET decreased sperm lipid peroxidation and decreased fertility, even at low doses. The presence of 4 mmol of SER significantly decreased lipid peroxidation, increased the frozen-thawed sperm quality, and increased fertility after sperm cryopreservation (90% vs. control 84%, P < 0.05). In a third experiment, the use of 1 mmol of sucrose (the best result of our previous study) added to 4 mmol of SER-supplemented extender was tested. This addition allowed to the highest levels of fertility (93%). In conclusion, the addition of 4 mmol of SER in semen cryopreservation diluents decreases peroxidation and improves the efficiency of the process.

Sucrose increases the quality and fertilizing ability of cryopreserved chicken sperms in contrast to raffinose

Chicken semen conservation is an important tool for programs of genetic diversity management and of endangered breeds’ conservation. However, the method still needs to be improved in order to be applied in a wide variety of environments and breeds. Our objective was to compare the effects of 2 external cryoprotectants saccharides (sucrose and raffinose) on the sperm freezability of a Thai local breed, Pradu Hang Dum, in which semen was frozen with a simple freezing method using nitrogen vapors and dimethyl formamide (DMF). Thirty-six males were selected on their motility vigor score for the experiments. In a first experiment, a large range of sucrose and raffinose doses were tested. Semen quality was evaluated after incubation at 5°C or after cryopreservation in straws in the saline Blumberger Hahnen Sperma Verdünner diluent + DMF (6% v/v) with or without sucrose/raffinose. The best targeted doses of sucrose and raffinose were then kept for experiment 2 that was focused on cryopreserved semen. In this experiment, semen quality was measured on frozen-thawed sperm: different objective motility data evaluated by computer-assisted sperm analysis (CASA), membrane integrity, acrosome integrity, mitochondria function evaluated using flow cytometry, lipid peroxide production assessed by the thiobarbituric acid test. Fertility obtained with frozen-thawed semen supplemented or not with sucrose or raffinose was also evaluated after artificial insemination of laying hens.

The presence of sucrose at the osmotically inactive dose 1 mmol significantly increased the vigor motility, membrane integrity, acrosome integrity, and mitochondrial functions of frozen-thawed sperm (P < 0.05), and showed the highest levels of fertility after sperm cryopreservation (91% vs. control 86%, P < 0.001). Raffinose showed negative effects on in vitro semen quality from 1 to 100 mmol. Fertility was also negatively (P < 0.001) affected by raffinose (fertility rate 66 to 70%).

We thus showed in the present study the high success of a simple chicken sperm cryopreservation method with an external cryoprotectant easily available and cheap, the sucrose, used at an osmotically inactive low concentration.

Semen cryopreservation in black-footed (Spheniscus demersus) and gentoo (Pygoscelis papua) penguins: Effects of thawing temperature on semen characteristics

In this study, there was an examination of the effect on the characteristics of cryopreserved black-footed (Spheniscus demersus) and gentoo (Pygoscelis papua) penguin semen, of thawing at 37 and 5 °C. For two consecutive years, semen was collected and frozen during the April-June period from six gentoo penguins, and during the October-November period from 13 black-footed penguins. After thawing, sperm motility variables were examined by computer-assisted sperm analysis. Propidium iodide and SYBR-14 were used as fluorochromes for the examination of membrane integrity. For the gentoo penguins, no differences were detected in the values of frozen-thawed semen characteristics after thawing at 37 or 5 °C. For the black-footed penguins, however, thawing at 5 °C resulted in greater values (P < 0.05) for straight-line velocity (VSL), average path velocity (VAP), linearity (LIN), straightness (STR), and wobble (WOB) as compared with thawing at 37 °C. After thawing at 37 ºC, there were greater values with gentoo penguin sperm for percentage motile sperm, progressive motility, curvilinear velocity (VCL), VSL VAP, LIN, STR, WOB and beat-cross frequency (BCF; P < 0.05) than that for black-footed penguin sperm. After thawing at 5 ºC, there were no differences in values for any variables between the two species. In conclusion, thawing temperature affects semen characteristics in a species-specific manner. The present data strongly suggest that cryopreservation procedures should be adapted for use with each penguin species. Cryopreserved black-footed penguin semen should be thawed after cryopreservation at 5 ºC, while that of gentoo penguins can be thawed at either 5 or 37 ºC.

Age-dependent changes in metabolic profile of turkey spermatozoa as assessed by NMR analysis

Metabolic profile of fresh turkey spermatozoa at three different reproductive period ages, namely 32, 44 and 56 weeks, was monitored by Nuclear Magnetic Resonance (NMR) spectroscopy and correlated to sperm quality parameters. The age-related decrease in sperm quality as indicated by reduction of sperm concentration, sperm mobility and osmotic tolerance was associated to variation in the level of specific water-soluble and liposoluble metabolites. In particular, the highest levels of isoleucine, phenylalanine, leucine, tyrosine and valine were found at 32 weeks of age, whereas aspartate, lactate, creatine, carnitine, acetylcarnitine levels increased during the ageing. Lipid composition also changed during the ageing: diunsaturated fatty acids level increased from 32 to 56 weeks of age, whereas a reduction of polyunsaturated fatty acids content was observed at 56 weeks. The untargeted approach attempts to give a wider picture of metabolic changes occurring in ageing suggesting that the reduction of sperm quality could be due to a progressive deficiency in mitochondrial energy producing systems, as also prompted by the negative correlation found between sperm mobility and the increase in certain mitochondrial metabolites.

Cryopreservation effects on sperm function and fertility in two threatened crane species

The capacity to cryopreserve semen from captive cranes facilitates production of offspring from behaviorally incompatible or geographically separated pairs, and allows for long-term preservation of valuable genetic materials. The present study sought to develop effective cryopreservation protocols for whooping (Grus americana) and white-naped (Grus vipio) cranes, through examining the influences of two permeating (DMA and Me₂SO) and one non-permeating (sucrose) cryoprotectants, as well as vitamin E on post-thaw sperm survival. In Study 1, ejaculates (whooping: n = 10, white-naped: n = 8) were collected and cryopreserved in one of six cryo-diluents (crane extender with: DMA; DMA+0.1M sucrose; Me₂SO; Me₂SO+0.1M sucrose; 0.1M sucrose; 0.2M sucrose) using a two-step cooling method. Frozen samples were thawed and assessed for overall motility, motion characteristics, membrane integrity, morphology, and ability to bind to the inner perivitelline membrane (IPVM). In Study 2, whooping crane ejaculates (n = 17) were frozen in crane extender containing Me₂SO alone or with vitamin E (5 μg/mL or 10 μg/mL). Frozen samples were thawed and assessed as in Study 1, except the binding assay. White-naped crane sperm were more tolerant to cryopreservation than whooping crane (15% vs 6% post-thawed motility). In both species, sperm cryopreserved in medium containing Me₂SO alone displayed higher post thaw survival and ability to bind to IPVM than the other cryodiluent treatments. Vitamin E supplementation exerted no benefits to post thaw motility or membrane integrity. The findings demonstrated that there was species specificity in the susceptibility to cryopreservation. Nevertheless, Me₂SO was a preferred cryoprotectant for sperm from both whooping and white-naped cranes.

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.

Intact Cell MALDI-TOF MS on Sperm: A Molecular Test For Male Fertility Diagnosis

Currently, evaluation of sperm quality is primarily based on in vitro measures of sperm function such as motility, viability and/or acrosome reaction. However, results are often poorly correlated with fertility, and alternative diagnostic tools are therefore needed both in veterinary and human medicine. In a recent pilot study, we demonstrated that MS profiles from intact chicken sperm using MALDI-TOF profiles could detect significant differences between fertile/subfertile spermatozoa showing that such profiles could be useful for in vitro male fertility testing. In the present study, we performed larger standardized experimental procedures designed for the development of fertility- predictive mathematical models based on sperm cell MALDI-TOF MS profiles acquired through a fast, automated method. This intact cell MALDI-TOF MS-based method showed high diagnostic accuracy in identifying fertile/subfertile males in a large male population of known fertility from two distinct genetic lineages (meat and egg laying lines). We additionally identified 40% of the m/z peaks observed in sperm MS profiles through a top-down high-resolution protein identification analysis. This revealed that the MALDI-TOF MS spectra obtained from intact sperm cells contained a large proportion of protein degradation products, many implicated in important functional pathways in sperm such as energy metabolism, structure and movement. Proteins identified by our predictive model included diverse and important functional classes providing new insights into sperm function as it relates to fertility differences in this experimental system. Thus, in addition to the chicken model system developed here, with the use of appropriate models these methods should effectively translate to other animal taxa where similar tests for fertility are warranted.

Ca2+/Calmodulin-Dependent Protein Kinase Kinases (CaMKKs) Effects on AMP-Activated Protein Kinase (AMPK) Regulation of Chicken Sperm Functions

Sperm require high levels of energy to ensure motility and acrosome reaction (AR) accomplishment. The AMP-activated protein kinase (AMPK) has been demonstrated to be strongly involved in the control of these properties. We address here the question of the potential role of calcium mobilization on AMPK activation and function in chicken sperm through the Ca²⁺/calmodulin-dependent protein kinase kinases (CaMKKs) mediated pathway. The presence of CaMKKs and their substrates CaMKI and CaMKIV was evaluated by western-blotting and indirect immunofluorescence. Sperm were incubated in presence or absence of extracellular Ca²⁺, or of CaMKKs inhibitor (STO-609). Phosphorylations of AMPK, CaMKI, and CaMKIV, as well as sperm functions were evaluated. We demonstrate the presence of both CaMKKs (α and β), CaMKI and CaMKIV in chicken sperm. CaMKKα and CaMKI were localized in the acrosome, the midpiece, and at much lower fluorescence in the flagellum, whereas CaMKKβ was mostly localized in the flagellum and much less in the midpiece and the acrosome. CaMKIV was only present in the flagellum. The presence of extracellular calcium induced an increase in kinases phosphorylation and sperm activity. STO-609 reduced AMPK phosphorylation in the presence of extracellular Ca²⁺ but not in its absence. STO-609 did not affect CaMKIV phosphorylation but decreased CaMKI phosphorylation and this inhibition was quicker in the presence of extracellular Ca²⁺ than in its absence. STO-609 efficiently inhibited sperm motility and AR, both in the presence and absence of extracellular Ca²⁺. Our results show for the first time the presence of CaMKKs (α and β) and one of its substrate, CaMKI in different subcellular compartments in germ cells, as well as the changes in the AMPK regulation pathway, sperm motility and AR related to Ca²⁺ entry in sperm through the Ca²⁺/CaM/CaMKKs/CaMKI pathway. The Ca²⁺/CaMKKs/AMPK pathway is activated only under conditions of extracellular Ca²⁺ entry in the cells.

The 5'-AMP-Activated Protein Kinase (AMPK) Is Involved in the Augmentation of Antioxidant Defenses in Cryopreserved Chicken Sperm

Semen cryopreservation is a unique tool for the management of animal genetic diversity. However, the freeze-thaw process causes biochemical and physical alterations which make difficult the restoration of sperm energy-dependent functions needed for fertilization. 5'-AMP activated protein kinase (AMPK) is a key sensor and regulator of intracellular energy metabolism. Mitochondria functions are known to be severely affected during sperm cryopreservation with deleterious oxidative and peroxidative effects leading to cell integrity and functions damages. The aim of this study was thus to examine the role of AMPK on the peroxidation/antioxidant enzymes defense system in frozen-thawed sperm and its consequences on sperm functions. Chicken semen was diluted in media supplemented with or without AMPK activators (AICAR or Metformin [MET]) or inhibitor (Compound C [CC]) and then cryopreserved. AMPKα phosphorylation, antioxidant enzymes activities, mitochondrial potential, ATP, citrate, viability, acrosome reaction ability (AR) and various motility parameters were negatively affected by the freeze-thaw process while reactive oxygen species (ROS) production, lipid peroxidation (LPO) and lactate concentration were dramatically increased. AICAR partially restored superoxide dismutase (SOD), Glutathione Peroxidase (GPx) and Glutathione Reductase (GR), increased ATP, citrate, and lactate concentration and subsequently decreased the ROS and LPO (malondialdehyde) in frozen-thawed semen. Motility parameters were increased (i.e., + 23% for motility, + 34% for rapid sperm) as well as AR (+ 100%). MET had similar effects as AICAR except that catalase activity was restored and that ATP and mitochondrial potential were further decreased. CC showed effects opposite to AICAR on SOD, ROS, LPO and AR and motility parameters. Taken together, our results strongly suggest that, upon freeze-thaw process, AMPK stimulated intracellular anti-oxidative defense enzymes through ATP regulation, thus reducing ROS and lipid peroxidation, and consequently partially restoring several essential sperm functions and leading to a better quality of cryopreserved sperm.

Central role of 5'-AMP-activated protein kinase in chicken sperm functions

Avian gametes present specific features related to their internal long-term mode of fertilization. Among other central actors of energetic metabolism control, it has been suspected that 5'-AMP-activated protein kinase (AMPK) influences sperm functions and thus plays a key role in fertilization success. In the present work, we studied AMPK localization and function in chicken sperm incubated in vitro. Effects of the pharmacological AMPK activators (AICAR, metformin) and the AMPK inhibitor compound C were assessed by evaluating AMPKalpha (Thr(172)) phosphorylation (by Western blotting), semen quality (by viability, motility, and ability to perform acrosome reaction), and energetic metabolism indicators (lactate, ATP). Localization of AMPK in subcellular sperm compartments was evaluated by immunocytochemistry. Total AMPK was found in all compartments except for the nucleus, but the phosphorylated form phospho-Thr(172)-AMPK was essentially localized in the flagellum and acrosome. AMPK activators significantly improved AMPK phosphorylation, sperm motility (increased by 40% motile, 90% progressive, and 60% rapid sperm), acrosome reaction and lactate production (increased by 40%) and viability. The AMPK inhibitor significantly reduced AMPK phosphorylation and percentages of motility (decrease by 25%), progressive energy (decrease by 35%), and rapid sperm (decreased by 30%), acrosome reaction, lactate production, and ATP release. The two activators differed in their effect on ATP concentration: AICAR stimulated ATP formation, whereas metformin did not. Our results indicate that AMPK plays a key role in the regulation of chicken sperm functions and metabolism. This action differs from that suggested in mammals, mainly by its crucial involvement in the acrosome reaction process.

Qualitative and quantitative peptidomic and proteomic approaches to phenotyping chicken semen

Understanding of the avian male gamete biology is essential to improve the conservation of genetic resources and performance in farming. In this study, the chicken semen peptidome/proteome and the molecular phenotype related to sperm quality were investigated. Spermatozoa (SPZ) and corresponding seminal plasma (SP) from 11 males with different fertilizing capacity were analyzed using three quantitative strategies (fluid and intact cells MALDI-MS, SDS-PAGE combined to LC-MS/MS with spectral counting and XIC methods). Individual MALDI profiling in combination with top-down MS allowed to characterize specific profiles per male and to identify 16 biomolecules (e.g.VMO1, AvBD10 and AvBD9 including polymorphism). Qualitative analysis identified 1165 proteins mainly involved in oxidoreduction mechanisms, energy processes, proteolysis and protein localization. Comparative analyses between the most and the least fertile males were performed. The enzymes involved in energy metabolism, respiratory chain or oxido-reduction activity were over-represented in SPZ of the most fertile males. The SP of the most and the least fertile males differed also on many proteins (e.g. ACE, AvBD10 and AvBD9, NEL precursor, acrosin). Thus proteomic is a "phenomic molecular tool" that may help to discriminate avian males on their reproductive capacity. The data have been deposited with ProteomeXchange (identifiers PXD000287 and PXD001254).

BIOLOGICAL SIGNIFICANCE

This peptidomic and proteomic study i) characterized for the first time the semen protein composition of the main domestic avian species (Gallus gallus) by analysis of ejaculated spermatozoa and corresponding seminal plasma; ii) established a characteristic molecular phenotype distinguishing semen and males at an individual level; and iii) proposedthe first evidence of biomarkers related to fertility.

Application of intracytoplasmic sperm injection (ICSI) for fertilization and development in birds

Intracytoplasmic sperm injection (ICSI) technology in birds has been hampered due to opacity of oocyte. We developed ICSI-assisted fertilization and gene transfer in quail. This paper reviews recent advances of our ICSI experiments. The oocyte retrieved from the oviduct and a quail sperm was injected into the oocyte under a stereomicroscope. The oocyte was cultured for 24h at 41°C under 5% CO2 in air. The fertilization and development was assessed by microscopic observation. The fertility rate ranged 12-18% and development varied from stage II to V in trials. To improve the fertility rate, phospholipase C (PLC) zeta was injected with a sperm. It was increased to 37-50%. Furthermore, injection of inositol trisphosphate increased to over 85%. Quail oocyte can be fertilized with chicken sperm and so can testicular elongated spermatid. To extend embryonic development, chicken eggshell was used as a surrogate culture at 37°C after the 24h incubation at 41°C under 5% CO2 in air. It survived up to 2days thereafter. Finally, gene transfer was attempted in quail egg. The sperm membrane was disrupted with Triton X-100 (TX-100) and was injected with PLCzeta cRNA and enhanced green fluorescent protein (EGFP) gene in oocyte. The GFP expression was evaluated at 24h incubation at 41°C under 5% CO2 in air in the embryos. While the expression was not detected in the control oocytes, the experimental treatment induced blastoderm development (44%) of the oocytes and 86% of blastoderm showed fluorescent emission. In addition, PCR analysis detected EGFP fragments in 50% of GFP-expressing blastoderm. Our ICSI method may be the first step toward the production of transgenic birds.

An efficient method of guinea fowl sperm cryopreservation

France is the only country that practices pedigree selection of guinea fowl for meat production. The increasing risk of line extinction for sanitary or breeding failure reasons makes clear the need for an efficient method of reproductive cell cryopreservation in this species. However, an efficient method of guinea fowl sperm freezing in secured packaging is still lacking. The aim of the present study was to develop such a method. Based on results previously obtained in chickens, different cryoprotectants and freezing/thawing processes were tested and then adapted to guinea fowl. Semen quality was measured by semen viability evaluation and then by fertility measured after intravaginal artificial insemination. The best results (70% fertility with frozen-thawed sperm) were obtained by the use of the permeant cryoprotectant agents dimethyl formamide combined with a freezing rate of 30°C/min. The initial insemination frequency also affected the fertility results: 2 consecutive days of inseminations were needed in the first week to ensure enough filling of the utero-vaginal glands of the guinea fowl hen and thus to get successive fertile eggs. Thereafter, a 2-wk insemination frequency was sufficient. This new method, combining biophysical (cryoprotectant agents, freeze/thaw rate) and zootechnical (artificial insemination frequency) features, is the first cryopreservation method successfully developed in secured packaging for guinea fowl sperm. This method is now available for the practice of gene bank conservation and male reproductive management.