A fast, low-cost and efficient method for the diagnosis of sperm DNA fragmentation in several species

Methylene blue-mediated antimicrobial photodynamic therapy on chicken semen

BACKGROUND

Artificial insemination is widely employed in poultry, but high degrees of bacterial contamination are often observed in semen because of its passage through the cloaca. Consequently, most semen extenders for birds have antibiotics that could aggravate bacterial resistance.

METHODS

We evaluated the potential of antimicrobial photodynamic therapy (PDT) as an alternative to the use of antibiotics, and assessed whether changes in concentration and incubation time with methylene blue (MB), radiant exposure, and irradiance of light affect spermatozoa activity and bacteria in chicken semen.

RESULTS

Incubation with MB (< 25 µM) did not alter sperm motility, regardless of the pre-irradiation time (PIT, 1 or 5 min). Following 1 min of PIT with MB at 10 µM, samples were irradiated for 30, 60, 120, and 180 s at irradiances of 44, 29, and 17 mW/ cm² (660 nm LedBox). MB and light alone did not interfere with the analyzed parameters. However, when both factors were associated, increases in light dose led to greater reductions in sperm parameters, regardless of the irradiance used. Besides, PDT conditions that were less harmful to spermatozoa were not able to significantly reduce bacterial colonies in chicken semen.

CONCLUSIONS

A failure in MB selectivity could explain unsuccessful bacterial reduction following PDT. Further research involving other photosensitizers or conjugating molecules to MB to target microbial cells is needed for PDT application in poultry breeders.

Ejaculate characteristics over seasons in five species of lancehead pitvipers (Bothrops spp) kept in captivity

Due to their major medical importance in Latin America, lancehead pitvipers are frequently kept and bred in captivity for venom extraction to the production of antivenom serums. Nevertheless, despite the great contribution given to captive breeding, much of the knowledge of Bothrops' reproductive biology derived from sporadic and insufficient data provided by zoological collections. Thus, we aimed to investigate seasonal changes in gonadosomatic index (GSI) and seminal parameters (e.g., volume, concentration, motility, viability, and acrosome integrity) of five species of lancehead pitvipers from different biomes and phylogenetic groups, maintained in the indoors serpentarium at Butantan Institute (Brazil). Patterns of variation in GSI and semen parameters differed from one species to another, suggesting that captive populations should perhaps be managed distinctly to maximize reproductive success. Furthermore, in none of the studied species did changes in GSI occur concomitantly with seminal variations. GSI remained unaltered year-round for Jararaca (Bothrops jararaca) and Brazilian lancehead (Bothrops moojeni), whereas it peaked in the autumn for Common lancehead (Bothrops atrox), Jararacussu (Bothrops jararacussu), and Whitetail lancehead (Bothrops leucurus). But surprisingly, the scenario was inverted when we estimated the total number of motile spermatozoa per season, as Jararaca and Brazilian lancehead displayed seasonal differences and the other species did not vary throughout the year. Potential ecological and evolutionary factors underlying these differences were also discussed in the present article. Together, these findings can help to better define breeding management strategies for each species in captivity, in addition to optimizing the future use of artificial insemination and semen cryopreservation.

Spirulina supplementation to the semen extender influences the quality and antioxidant parameters of chilled or cryopreserved Arabian stallion spermatozoa

The present study attempted to investigate the effect of various concentrations of spirulina platensis additions to the semen extender on Arabian stallion spermatozoa quality. Semen samples were collected with artificial vagina from five fertile stallions and diluted with an extender containing spirulina (2, 4, 6, and 8 mg/100 mL) or without spirulina (control). Aliquots of diluted semen were cooled (5°C, 90 min.) and frozen (-196°C, 7 d), then physical traits of thawed spermatozoa were examined. Furthermore, antioxidant activities of superoxide dismutase (SOD), glutathione reductase (GSR), total antioxidant capacity (TAC), and malondialdehyde (MDA) were measured in post-cooling and freezing spermatozoa. The results indicated that spirulina supplemented with the extender had no effect (P > 0.05) on sperm quality parameters and antioxidant activities after cooling. However, adding 6 mg spirulina/100 mL to the freezing extender improved (P < 0.05) the speed parameters and total motility percentage of frozen/thawed spermatozoa. Besides, supplementation of freezing extender with the previous level increased (P < 0.05) TAC, SOD and GSR concentrations/activities (0.86 ± 0.32 mM/L, 323.70 ± 12.81 U/mL, and 38.65 ± 1.90 U/mL, respectively) compared with the control (0.70 ± 0.25 mM/L, 165.80 ± 8.12 U/mL, and 25.70 ± 1.83 U/mL, respectively). While, lipid peroxidation of the frozen-thawed semen was reduced (P < 0.05, 17.97 ± 1.30 µmol/ L) compared with the control (29.39 ± 1.89 µmol/ L). Accordingly, the present results revealed that additions of 6 mg spirulina/100 mL to the freezing extender improved semen quality and reduced cryodamage of the Arabian stallion spermatozoa.

Frozen-Thawed Sperm Analysis of Benign Prostatic Hyperplasia Dogs Treated With Finasteride

Benign Prostatic Hyperplasia (BPH) is a pathological condition that directly interferes with the reproductive potential of senile dogs, by leading to prostate enlargement and sperm injury, which in turn may compromise sperm freezeability. Moreover, albeit finasteride treatment reduces prostatic volume and blood supply and maintains seminal quality and testicular integrity, the effects of sperm samples submitted to cryopreservation after the finasteride treatment are still unknown. Thus, the aim of this study was to evaluate frozen-thawed semen of BPH dogs, as well as dogs subjected to BPH pharmacological treatment with finasteride. For such purpose, 20 dogs were previously selected and assigned to three experimental groups, according to BPH diagnosis and treatment with finasteride: Control (n = 9), BPH Group (n = 5) and BPH-Finasteride Group (n = 6). Semen was subjected to one-step cryopreservation protocol with tris-fructose-citric acid extender with 5% glycerol and thawed at 37°C for 30 sec. Fresh and post-thaw sperm samples were evaluated for macroscopic parameters, sperm concentration, sperm motility kinetics, sperm mitochondrial activity and potential, oxidative stress, plasmatic and acrosome membrane integrity, sperm DNA fragmentation and sperm binding test on perivitelic membrane of chicken egg yolk. Regarding fresh semen, BPH-Finasteride group had the lowest ejaculate visual aspect (opacity), higher frequency of sperm flagellar beating (BCF) and percentage of sperm with medium velocity. Control group had the highest percentage of sperm DNA integrity compared to BPH group. For the frozen-thawed semen, Control group presented the highest percentage of spermatozoa with high mitochondrial activity. However, the BPH-Finasteride group showed higher number of sperm bound to the perivitelline membrane of chicken egg yolk compared to the BPH Group. Conversely, BPH group had higher percentage of DNA damage. In conclusion, the ejaculate of BPH dogs has higher susceptibility to cryoinjury, whereas finasteride-treated dogs have increased spermatozoa functional performance, suggesting a promising use of BPH dogs as semen donors in sperm cryopreservation programs.

Canine Spermatozoa—Predictability of Cryotolerance

Simple Summary

Semen freezing in dogs is a field of growing interest. The international shipment of cryoconserved semen contributes to the avoidance of long travels and long-term storage of valuable gametes. However, the collection of one semen portion on average results in one to three doses for artificial insemination, which is a poor result in comparison to the outcome in large animals. The costs for the owners are therefore rather high. In individual dogs, the semen quality of raw semen is good; however, it could be suboptimal after thawing. To avoid costly freezing of these low-quality ejaculates, markers of freezability are useful. An abundance of markers are available for large animals, but not for dogs. This review provides an overview on markers for freezability of canine semen.

Abstract

Markers of freezability allow the selection of ejaculates of good freezability. So far, most investigations were conducted in boars, bulls, rams and horses, with high economic interests triggering the efforts. The progress in dogs is comparably slow. A critical evaluation of the methods requires consideration of practicability, with most labs not even possessing a computer assisted sperm analyser (CASA); furthermore, small canine ejaculates mostly do not allow the use of large semen volumes. In dogs, modern markers of freezability no longer assess single membrane constituents or seminal plasma components but comprise tests of cell functionality and adaptability, energy metabolism, cluster analyses of kinetic and morphometric parameters, as well as DNA intactness. Identification of the most efficient combination of tests seems useful. At present, examination by CASA combined with cluster analysis of kinetic subgroups, JC-1 staining and COMET assay or staining with toluidine blue seem most appropriate; however, cell volumetry and other functional tests deserve better attention. A better understanding of spermatozoa energy metabolism might reveal new markers. This review focuses on the requirements and markers of freezability of canine semen, highlighting potential future candidates.

Practical methods to assess the effects of heat stress on the quality of frozen-thawed Belgian Blue semen in field conditions

The increased exportation of semen and embryos of double-muscled beef breeds to tropical and developing countries makes it important to investigate the reproductive capacity of these breeds in adapting to tropical conditions. The aim of this study was to evaluate the quality of Belgian Blue semen collected after there is heat-stress (HS; as a mimic of tropical condition) compared with non-heat stressed (NHS; as their comfort zone), using practical spermatozoa staining methods such that prevail in developing countries. There was screening of semen kinetics using CASA and evaluation of their DNA-, acrosome, plasma membrane-integrity, and mitochondrial activity. For each staining technique, there was evaluation of 12 frozen-thawed semen samples from six Belgian Blue bulls collected after there were HS and NHS conditions in Belgium. Mixed linear regression models were used to assess the effects of HS for each CASA variable and staining method outcome using the replicate nested with bull as a random effect. There were differences (P < 0.05) in values when there were semen collections following HS and NHS conditions for several post-thawing kinetic variables. Furthermore, the mean percentages of DNA-, acrosome-, and plasma membrane-integrity, as well as mitochondrial activity were greater (P < 0.05) when semen was collected following NHS compared with HS conditions. Conclusively, results indicated that when there was collection of semen following HS conditions, there were detrimental effects on the viability and quality of Belgian Blue semen which is an important consideration for the semen collection, processing, and evaluation in tropical countries.

Does finasteride treatment for benign prostatic hyperplasia influence sperm DNA integrity in dogs?

BACKGROUND

Benign prostatic hyperplasia (BPH) is one of the most common reproductive disorders in both male dogs and men. Finasteride, a synthetic inhibitor of the enzyme 5α-reductase, is widely used as medical treatment. Although sperm can be affected by both BPH and finasteride treatment, the direct influence on DNA integrity remains unclear. Thus, the aim of this study was to verify the direct effect of BPH and/or finasteride treatment on DNA integrity of dog spermatozoa. A 2 × 2 factorial experiment was designed with 20 male dogs assigned to 4 experimental groups: BPH Group (n = 5), BPH-Finasteride Group (n = 5), Non-BPH Finasteride-Treated Group (n = 5) and Non-BPH Untreated Group (n = 5). Sperm evaluation was performed monthly for 60 days after the start of finasteride therapy or BPH diagnosis (D0, D30 and D60). Sperm DNA integrity was analyzed through fragmentation susceptibility (toluidine blue staining and Sperm Chromatic Structure Assay - SCSA), direct evaluation of DNA fragmentation (Sperm Chromatin Dispersion Assay - SCDA) and sperm protamination (chromomycin A3).

RESULTS

Sperm DNA integrity was not affected by finasteride treatment. However, BPH dogs had higher susceptibility to sperm DNA acid denaturation (SCSA) compared to dogs not presenting BPH, as well as lower percentage of sperm with DNA integrity (toluidine blue staining).

CONCLUSION

In conclusion, benign prostatic hyperplasia causes post-testicular sperm DNA damage, albeit finasteride treatment itself does not directly influence sperm DNA integrity.

Effect of supplementation of Aloe vera extracts in cold storage media and cryopreservation of domestic cat epididymal spermatozoa

This study evaluated the effect of the extract of Aloe vera at concentrations of 10% and 20% on the cryopreservation of sperm from the epididymis of domestic cats. Epididymal spermatozoa were recovered using the flotation technique and used in the treatments: control (TRIS-egg yolk at 20%), T10% (TRIS plus 10% of A. vera extract), and T20% (TRIS plus 20% of A. vera extract). The spermatozoa were subjected to 4ºC for 60 minutes, followed by 20 minutes in nitrogen vapors, and stored in a cryogenic cylinder. The samples were thawed at 37°C for 30 seconds. The sperm motility decreased (P<0.05) after thawing in the three treatments. Only the spermatozoa in the control treatment maintained post-thawing vigor. The viability of spermatozoa decreased in the treatments with A. vera (P<0.05). According to the hypoosmotic test, all treatments maintained the sperm membrane functionality (P>0.05) during freezing; however, after thawing, it decreased (P<0.05) in the T10% and T20% treatments. The morphology and chromatin condensation of spermatozoa did not differ, regardless of the treatments and time of evaluation (P>0.05). The effect of the crude A. vera extract was not satisfactory on the cryopreservation of epididymal spermatozoa of domestic cats after thawing; although the motility of spermatozoa was similar to that found with the use of egg yolk, and it presented maintenance of the chromatin integrity. However, it is necessary to understand the action of the substances present in A. vera with the feline spermatozoa, well as the standardization and adjustment of physicochemical characteristics aiming at the future application of the vegetal extract.

Sperm DNA fragmentation: causes and identification

Sperm DNA fragmentation is referred to as one of the main causes of male infertility. Failures in the protamination process, apoptosis and action of reactive oxygen species (ROS) are considered the most important causes of DNA fragmentation. Action of ROS or changes in sperm protamination would increase the susceptibility of sperm DNA to fragmentation. Routine semen analysis is unable to estimate sperm chromatin damage. Sperm DNA integrity influences sperm functional capability, therefore tests that measure sperm DNA fragmentation are important to assess fertility disorders. Actually, there is a considerable number of methods for assessing sperm DNA fragmentation and chromatin integrity, sperm chromatin stability assay (SCSA modified), sperm chromatin dispersion (SCD), comet assay, transferase dUTP nick end labelling (TUNEL); and protamine evaluation in sperm chromatin assay, such as toluidine blue, CMA3, protamine expression and evaluation of cysteine radicals. This review aims to describe the main causes of sperm DNA fragmentation and the tests commonly used to evaluate sperm DNA fragmentation.

Use of microfluidic sperm extraction chips as an alternative method in patients with recurrent in vitro fertilisation failure

PURPOSE

It is known that sperm preparation techniques in in vitro fertilisation (IVF) are intended to select the best-quality sperm. The aim of this study is to compare sperm the density gradient method and microfluidic chip (Fertile Plus) method in infertile patients by analysing fertilisation rates, pregnancy rates, and sperm morphology and DNA fragmentation rates posed by these two methods.

METHODS

Using semen samples obtained from the patients, sperms were prepared with gradient (n = 312) and microfluidic chip methods (n = 116). Fertilisation and pregnancy rates were compared in the first time and in the recurrent IVF trial patients. In addition, the morphology and DNA fragmentation comparison of sperm samples were evaluated by Toluidine blue in situ chemical staining method.

RESULTS

There was no statistically significant difference between fertilisation and pregnancy rates when compared with study groups in first-time IVF treatment patients. However, in recurrent IVF failure patients, there was a significant difference in fertilisation rates but no statistically significant difference was found in pregnancy rates. The microfluidic chip method significantly decreased sperm DNA fragmentation index according to density gradient method.

CONCLUSIONS

Microfluidic chip method may be recommended in patients with recurrent unsuccessful in vitro trials. The sperm DNA fragmentation test prior to the treatment will be helpful in selecting the appropriate sperm-washing method.

Toluidine blue staining for cell and tissue biology applications

Toluidine blue (TB) staining either alone or in association with other methodologies has the potential to answer a variety of biological questions regarding the human, animal and plant tissues or cells. In this brief review, we not only report the primary use of TB to detect the anionic substrates and availability of their binding sites, but also unveil the resulting applications of TB staining in biological research. Among these applications, the uses of TB staining to identify the changes in chromatin DNA-protein complexes, nucleolus location, and extracellular matrix proteoglycan complexes associated with different physiological and pathological events are described. The usefulness of TB staining to monitor the effects elicited by environmental insults on chromatin and intercalation of drugs into the DNA is also included.