scholarly journals Sperm Nuclei Analysis and Nuclear Organization of a Fertile Boar–Pig Hybrid by 2D FISH on Both Total and Motile Sperm Fractions

Animals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 738
Author(s):  
Viviana Genualdo ◽  
Federica Turri ◽  
Flavia Pizzi ◽  
Bianca Castiglioni ◽  
Donata Marletta ◽  
...  
Keyword(s):  
Sus Scrofa ◽  
Semen Quality ◽  
Sperm Quality ◽  
Nuclear Architecture ◽  
Sperm Chromatin ◽  
Fish Analysis ◽  
Motile Sperm ◽  
Screening Programs ◽  
Wide Range ◽  
Sperm Nuclei

A wide range of mammalian hybrids has recently been found by chance or through population-screening programs, but studies about their fertilizing capacity remain scarce and incomplete. Most of them are assumed to be sterile due to meiotic arrest caused by the failure of chromosome pairings. In this study, we evaluated both sperm meiotic segregation, by 2D fluorescent in situ hybridization (FISH) analysis, and sperm quality (Sperm Chromatin Structure Assay) by flow cytometer in a fertile boar–pig hybrid (2n = 37,XY) originating from a Nero Siciliano pig breed (Sus scrofa domesticus) and a wild boar (Sus scrofa ferus). Spermatozoa were also separated by a dual-layer (75–60%) discontinuous Percoll gradient, resulting in two fractions with a significantly better overall quality in the motile sperm fraction. These data were confirmed by FISH analysis also, where the frequencies of spermatozoa with a regular chromosome composition were 27% in total sperm fraction and 64% in motile sperm fraction. We also evaluated the nuclear architecture in all counted spermatozoa, showing a chromatin distribution changing when chromosome abnormalities occur. Our results demonstrate that the chromosome pairing has a minimal effect on the sperm segregation and semen quality of a boar–pig hybrid, making it fertile and harmful for the conservation of autochthonous pig breeds.

scholarly journals Mitochondria Content and Activity Are Crucial Parameters for Bull Sperm Quality Evaluation

Antioxidants ◽  
2021 ◽  
Vol 10 (8) ◽  
pp. 1204
Author(s):  
Zofia E. Madeja ◽  
Marta Podralska ◽  
Agnieszka Nadel ◽  
Marcin Pszczola ◽  
Piotr Pawlak ◽  
...  
Keyword(s):  
Quality Evaluation ◽  
Semen Quality ◽  
Sperm Quality ◽  
Transcript Level ◽  
Glutathione Synthetase ◽  
Motile Sperm ◽  
Bovine Sperm ◽  
Cryopreserved Sperm ◽  
Group 2 ◽  
Group 1

Standard sperm evaluation parameters do not enable predicting their ability to survive cryopreservation. Mitochondria are highly prone to suffer injuries during freezing, and any abnormalities in their morphology or function are reflected by a decline of sperm quality. Our work focused on describing a link between the number and the activity of mitochondria, with an aim to validate its applicability as a biomarker of bovine sperm quality. Cryopreserved sperm collected from bulls with high (group 1) and low (group 2) semen quality was separated by swim up. The spermatozoa of group 1 overall retained more mitochondria (MitoTrackerGreen) and mtDNA copies, irrespective of the fraction. Regardless of the initial ejaculate quality, the motile sperm contained significantly more mitochondria and mtDNA copies. The same trend was observed for mitochondrial membrane potential (ΔΨm, JC-1), where motile sperm displayed high ΔΨm. These results stay in agreement with transcript-level evaluation (real-time polymerase chain reaction, PCR) of antioxidant enzymes (PRDX1, SOD1, GSS), which protect cells from the reactive oxygen species. An overall higher level of glutathione synthetase (GSS) mRNA was noted in group 1 bulls, suggesting higher ability to counteract free radicals. No differences were noted between basal oxygen consumption rate (OCR) (Seahorse XF Agilent) and ATP-linked respiration for group 1 and 2 bulls. In conclusion, mitochondrial content and activity may be used as reliable markers for bovine sperm quality evaluation.

50 ESTIMATION OF CHROMATIN ABNORMALITY OF OGYE ROOSTER SEMEN WITH Diff-Quik STAINING

2016 ◽  
Vol 28 (2) ◽  
pp. 155
Author(s):  
S. W. Kim ◽  
A. R. Choi ◽  
C. Y. Choe ◽  
D. K. Kim ◽  
H. H. Seong ◽  
...  
Keyword(s):  
Staining Method ◽  
Sperm Quality ◽  
Sperm Head ◽  
Head Movements ◽  
Sperm Chromatin ◽  
Frozen Semen ◽  
Sperm Nuclei ◽  
Live Sperm ◽  
The Relationship ◽  
Fresh Semen

The abnormality of Ogye rooster sperm chromatin could be detected by simple sperm staining. In this abstract, a Diff-Quick staining kit was tested for assessment of chicken sperm quality. Using a standard bright-field microscope, Diff-Quik stains can be reproducibly, easily, and routinely monitored with simple staining. The presence of abnormal chromatin staining of rooster sperm was determined by darker stain in head. In the fresh semen, the viabilities of 3 tested Ogye spermatozoa were 93.53, 82.42, and 90.63%, and normal chromatin rates were 87.96, 74.25, and 85.10%, respectively. However, after cryopreservation, the rates of viability of thawed semen were reduced to 69.58, 61.98, and 72.20%, and normal chromatin rate also reduced to 58.91, 48.49, and 63.34%. A significant correlation between live sperm and normal sperm nuclei was 0.875 in fresh semen and 0.513 in frozen semen. After incubation of sperm at 37°C for 5 min, the rates of viability, chromatin normality, and sperm head activity were shown as 90.63 ± 1.28%, 82.44 ± 8.09%, and 66.68 ± 10.29% in fresh semen. However, the rates of thawed semen were reduced to 67.92 ± 7.55%, 56.92 ± 12.15%, and 47.32 ± 5.02%, respectively. The relationship between chromatin normality and sperm head movements in fresh and thawed semen were 0.564 and 0.540, respectively. With these results, the chicken sperm normality could be assessed by the Diff-Quik staining, which could be used for chromatin status of sperm head and activated morphology of live spermatozoa, as a simple and rapid staining method.

scholarly journals A randomized placebo-controlled trial to investigate the effect of lactolycopene on semen quality in healthy males

2019 ◽  
Vol 59 (2) ◽  
pp. 825-833 ◽  
Author(s):  
Elizabeth A. Williams ◽  
Madeleine Parker ◽  
Aisling Robinson ◽  
Sophie Pitt ◽  
Allan A. Pacey
Keyword(s):  
Primary Endpoint ◽  
Semen Quality ◽  
Sperm Quality ◽  
Controlled Trial ◽  
Sperm Concentration ◽  
Dietary Factors ◽  
Motile Sperm ◽  
Heterosexual Couples ◽  
Double Blind ◽  
Healthy Men

Abstract Purpose Poor sperm quality is a major contributor to infertility in heterosexual couples, but at present there are few empirical therapies. Several studies have examined the role of dietary factors and data from randomized controlled trials suggest that oral antioxidant therapy can improve some sperm parameters. Health benefits of lycopene supplementation have been proposed for a variety of health conditions and here we examine whether it can help improve sperm quality. This study aimed to investigate the effect of 14 mg daily lactolycopene for 12 weeks on semen quality in healthy men. Methods Sixty healthy male participants were recruited and randomized to this double-blind, placebo-controlled parallel study and received either 14 mg/d lactolycopene or a placebo for 12 weeks. The primary endpoint was a change in motile sperm concentration. Secondary endpoints were all other aspects of sperm quality, including the level of sperm DNA damage. Results Fifty-six men completed the intervention and the level of plasma lycopene was significantly increased in the men randomized to receive lycopene supplementation. There was no significant change in the primary endpoint (motile sperm concentration) post-intervention (p = 0.058). However, the proportion of fast progressive sperm (p = 0.006) and sperm with normal morphology (p < 0.001) did improve significantly in response to lactolycopene intervention. Conclusions Supplementation with 14 mg/d lactolycopene improves sperm motility and morphology in young healthy men. Clinical Trial Registry number and website ISRCTN33248724 http://www.isrctn.com/ISRCTN33248724

P–063 The influence of lifestyle factors on sperm quality by motile sperm organelle morphology examination (MSOME)

2021 ◽  
Vol 36 (Supplement_1) ◽  
Author(s):  
A Sebastianelli ◽  
F Battaglia ◽  
L Caponecchia ◽  
C Fiori ◽  
I Marcucci ◽  
...  
Keyword(s):  
Semen Quality ◽  
Positive Impact ◽  
Sperm Quality ◽  
Semen Analysis ◽  
Lifestyle Factors ◽  
World Health ◽  
Semen Parameters ◽  
Base System ◽  
Motile Sperm ◽  
Organelle Morphology

Abstract Study question This study aimed to investigate the influence of lifestyle factors on sperm quality according to Motile Sperm Organelle Morphology Examination (MSOME) criteria. Summary answer The introduction of MSOME permits the examination of subcellular defect like nuclear vacuoles at hight magnification (6000x) in real time on vital sperm. What is known already It is increased accepted that lifestyle factors have an impact on sperm quality. Recent evidence shows that the selection of spermatozoa based on the analysis of morphology under high magnification may have a positive impact on embryo development in cases with severe male factor infertility and/or previous implantation failures. Therefore, MSOME has been considered as representing an improvement in the evaluation of semen quality. Although numerous studies have shown the influences of nutrition, lifestyle, age on semen quality, only very few study, have considered the influence of these factors on the vacuolization rate in semen analysis (MSOME criteria) Study design, size, duration The objective of this prospective study was to compare the semen parameters of 87 male patients undergoing evaluation or treatment of infertility at Unit of Pathophysiology of Reproduction ad PMA-Santa Maria Goretti Hospital -Latina according to MSOME and WHO (World Health Organization) criteria between January and September 2019.Written informed consent was obtained from all partecipant of this study. Participants/materials, setting, methods The subjects were divided into three groups according to age: Group 1 ≤ 35 yearş group II ,36–40 years; and Group III ≥ to 41 years .All patients filled a questionnaire answering questions regarding age, BMI, caffeine and alcohol consumptions, smoking and nutrition behavior. Were excluded from the study patients with chromosomal alteration. For multifactorial lifestyle influence patients were evaluated with a point base system with a cut-off &gt;2 and cut off&lt;3 for unhealthy style. Main results and the role of chance There was no difference between the groups with regard all semen parameters such as volume, concentration, number of leukocytes, morphology and vitality (%).The percentage of spermatozoa with LNV (Large Nuclear vacuoles) was significantly higher in the older group than in the younger (I and II) (39,14±13,74 vs 31,8±12 and 31,7 ±13,4 rispectively (p &lt; 0,05)which does not correspond to a worsening of semen morphology. Regression analysis demonstrated a correlation between the percentage of spermatozoa with LNV and male age (r = –0,1) (p &lt; 0,001). There was no correlation between lifestyle parameters ad enviroments factors . Comparing the semen parameters of healthy and unhealthy population we found no difference except a significantly higher number of spermatozoa with vacuoles in the unhealthy population (p &lt; 0.001) Limitations, reasons for caution Although the sample examined in this study is limited in size and other studies are needed to confirm this evidence, the data available to us support the routine use of MSOME for ICSI and as a criterion for semen analysis with potential clinical repercussions. Wider implications of the findings: To date, there are few works in the literature that analyze the relationship between the morphology assessed with the MSOME and the age of the patients and the results are conflicting. To our knowledge many works agree with our results. Trial registration number Not applicable

191 SexedULTRA™, A NEW METHOD OF PROCESSING SEX SORTED BOVINE SPERM IMPROVES POST-THAW SPERM QUALITY AND IN VITRO FERTILITY

2017 ◽  
Vol 29 (1) ◽  
pp. 204 ◽  
Author(s):  
C. Gonzalez-Marin ◽  
R. W. Lenz ◽  
T. B. Gilligan ◽  
K. M. Evans ◽  
C. E. Gongora ◽  
...  
Keyword(s):  
Mixed Model ◽  
Semen Quality ◽  
Sperm Quality ◽  
Random Effect ◽  
Fixed Effect ◽  
Computer Assisted ◽  
Motile Sperm ◽  
Bovine Sperm ◽  
Mixed Model Anova

Since the first publications 30 years ago showing that flow cytometry was a reliable method to separate X and Y chromosome bearing sperm, the process has been subject to continual refinement. Numerous experiments have been performed in the last few years with the objective of developing an improved sex-sorted product, branded SexedULTRA™ (Sexing Technologies, Navasota, TX, USA) that retains sperm integrity to improve post-thaw sperm quality, in vitro embryo production, and field fertility compared with the previous XY method. Laboratory evaluations were performed on semen from 12 bulls at the Sexing Technologies laboratory in Navasota (TX, USA). Each ejaculate was divided in 2 aliquots and then processed in 1 of 2 methods (XY method or SexedULTRA™). Post-thaw sperm motilities were classified into percent total and progressively motile after thawing (0 h) and after a 3-h incubation at 37°C using a computer-assisted sperm motility analyzer (Hamilton Thorne IVOS II system, Hamilton Thorne Biosciences, Beverly, MA, USA). Percent intact acrosomes was also estimated after a 3-h incubation. Results were analysed by a mixed model ANOVA with the fixed effect of treatment and random effect of bull. Percent total motile SexedULTRA™ sperm was greater (P < 0.001) than sperm processed following the XY method at 0 (78.8 v. 67.2%) and 3 h (51.0% v. 39.0%) post-thaw. Likewise, there was a higher percent of progressively motile sperm both at 0 (50.7 v. 44.9%) and 3 h (31.5 v. 4.4%) post-thaw in the SexedULTRA™ sperm. Percent intact acrosomes was also greater in SexedULTRA™ sperm compared with the sperm processed following previous method (78.0 v. 64.0%). In vitro fertilizations were performed as a measure of sperm competence using 8 ejaculates from 2 bulls in Sexing Technologies IVF laboratory in Laceyville (PA, USA). Five to 10 oocytes and 5,000 motile sperm/oocyte were placed per IVF drop for the analysis. A total of 3 straws and a minimum of 800 oocytes per treatment group (ejaculate × treatment) were included in the comparison for development to 8-cell stage (cleavage rate) and to Day 7 blastocyst stage, measured as total (grades 1 to 4) and freezable (grades 1 and 2) embryos. Results were analysed using a mixed model ANOVA with treatment as a fixed effect and bull, ejaculate within bull, and IVF cycle as random effects. Results from IVF trials are shown in Table 1. Total and freezable embryo numbers were significantly higher (P < 0.05) when using SexedULTRA™ compared with XY sperm. Maintaining a suitable environment for sperm to progress through the various steps of the sex-sorting process results in better semen quality post-thaw as well as improved in vitro fertility. The SexedULTRA™ method confers a significant benefit in maintaining sperm integrity that, if translated into field fertility, could reduce the conception rate gap between conventional and sex-sorted bovine sperm. Table 1. Results from IVF and embryo culture using frozen-thawed, sex-sorted semen processed using the XY or the SexedULTRA™ method

scholarly journals Key gene regulatory sequences with distinctive ontological signatures associate with differentially endonuclease-accessible mouse sperm chromatin

Reproduction ◽  
2011 ◽  
Vol 142 (1) ◽  
pp. 73-86 ◽  
Author(s):  
Myriam Saida ◽  
David Iles ◽  
Abdul Elnefati ◽  
Martin Brinkworth ◽  
David Miller
Keyword(s):  
In Silico ◽  
Methylation Status ◽  
Micrococcal Nuclease ◽  
Ctcf Binding ◽  
Sperm Chromatin ◽  
Regulatory Sequences ◽  
Fish Analysis ◽  
Gene Promoters ◽  
Mouse Sperm ◽  
Sperm Nuclei

Using a well-established endonuclease-based chromatin dissection procedure in conjunction with both experimental comparative genome hybridisation (CGH) array profiling andin silicodata mining, we show that mouse spermatozoa contain chromatin that is sensitive and resistant to digestion with micrococcal nuclease (MNase). Sequences represented in the micrococcal nuclease digestion solubilised (MNDS) but not the MND insoluble (MNDI) chromatin are strongly enriched in chromosomal regions of high gene density. Furthermore, by fluorescencein situhybridisation (FISH) analysis, we show that MNDS and MNDI DNAs occupy distinct domains of decondensed mouse sperm nuclei that may also retain abundant histones. More detailedin silicoanalysis of CGH probe location in relation to known promoters and sequences recognised by CCCTC binding factor (CTCF) shows a significant excess of both in MNDS chromatin. A functional analysis of gene promoters reveals strong ontological signatures for ion transport on methylated promoters associated with CTCF binding sequences in MNDS chromatin. Sensory perception is the only strong ontological signature present in MNDI chromatin, driven by promoters that are not associated with CTCF regardless of their methylation status.

The Prevalence of Bacteriospermia in Infertile Men and Association with Semen Quality in Southwestern Iran

2020 ◽  
Vol 20 (2) ◽  
pp. 198-202 ◽  
Author(s):  
Mohammad Motamedifar ◽  
Yalda Malekzadegan ◽  
Parisa Namdari ◽  
Behzad Dehghani ◽  
Bahia Namavar Jahromi ◽  
...  
Keyword(s):  
Semen Quality ◽  
Sperm Quality ◽  
Reproductive Function ◽  
World Health ◽  
Public Health Issue ◽  
Control Group ◽  
Microbiological Analysis ◽  
Male Reproductive Function ◽  
Infertile Men ◽  
Southwestern Iran

Introduction: Infertility considered as a social and public health issue and estimated that most of these infertile couples are residents of developing countries. Infectious diseases including the history of Sexually Transmitted Infections (STIs) may impact on male reproductive function. Therefore, the present study aimed to investigate the prevalence of bacterial contaminants of semen and probable association with sperm quality of infertile men in Iranian population. Methods: The study population consisted of 200 infertile men and 150 fertile men attending an infertility Center in southwestern Iran during the study period in 2015. The assessment of sperm parameters was according to the World Health Organization (WHO) guidelines. The presumptive pathogens were identified using standard microbiology tests and confirmed by specific PCR primers. Results: The prevalence of bacteriospermia in the semen of the infertile group was significantly higher than that in the fertile group (48% vs. 26.7%, P <0.001). The microbiological analysis of samples showed that the most abundant species of bacteria in semen of infertile men were Chlamydia trachomatis (12.5%) followed by Neisseria gonorrhoeae (11%). On the other hand, in the control group, Lactobacillus spp. (17.3%) was the most isolated pathogen. Results showed that the presence of N. gonorrhoeae, C. trachomatis, Mycoplasma genitalium, Haemophilus, and Klebsiella was significantly associated with sperm abnormality. Conclusion: Based on our findings, it seems that bacteriospermia is associated with alterations in the properties of semen which may lead to a decrease in the fertilization potential of sperm. Therefore, immediate and appropriate treatment is necessary before investigating every other possible cause of infertility.

Restraint stress of male mice triggers apoptosis in spermatozoa and spermatogenic cells via activating the TNF-α system

Zygote ◽  
2020 ◽  
Vol 28 (2) ◽  
pp. 160-169 ◽  
Author(s):  
Jie Zhang ◽  
De-Ling Kong ◽  
Bin Xiao ◽  
Hong-Jie Yuan ◽  
Qiao-Qiao Kong ◽  
...  
Keyword(s):  
Psychological Stress ◽  
Restraint Stress ◽  
Semen Quality ◽  
Sperm Quality ◽  
Fertilization Rate ◽  
Seminiferous Tubules ◽  
Spermatogenic Cells ◽  
Male Mice ◽  
Testicular Cells ◽  
Tnf Α

SummaryStudies have indicated that psychological stress impairs human fertility and that various stressors can induce apoptosis of testicular cells. However, the mechanisms by which psychological stress on males reduces semen quality and stressors induce apoptosis in testicular cells are largely unclear. Using a psychological (restraint) stress mouse model, we tested whether male psychological stress triggers apoptosis of spermatozoa and spermatogenic cells through activating tumour necrosis factor (TNF)-α signalling. Wild-type or TNF-α−/− male mice were restrained for 48 h before examination for apoptosis and expression of TNF-α and TNF receptor 1 (TNFR1) in spermatozoa, epididymis, seminiferous tubules and spermatogenic cells. The results showed that male restraint significantly decreased fertilization rate and mitochondrial membrane potential, while increasing levels of malondialdehyde, active caspase-3, TNF-α and TNFR1 in spermatozoa. Male restraint also increased apoptosis and expression of TNF-α and TNFR1 in caudae epididymides, seminiferous tubules and spermatogenic cells. Sperm quality was also significantly impaired when spermatozoa were recovered 35 days after male restraint. The restraint-induced damage to spermatozoa, epididymis and seminiferous tubules was significantly ameliorated in TNF-α−/− mice. Furthermore, incubation with soluble TNF-α significantly reduced sperm motility and fertilizing potential. Taken together, the results demonstrated that male psychological stress induces apoptosis in spermatozoa and spermatogenic cells through activating the TNF-α system and that the stress-induced apoptosis in spermatogenic cells can be translated into impaired quality in future spermatozoa.

scholarly journals Macro- and microelements in serum and seminal plasma as biomarkers for bull sperm cryotolerance

2021 ◽  
Vol 63 (1) ◽  
Author(s):  
Maja Zakošek Pipan ◽  
Petra Zrimšek ◽  
Breda Jakovac Strajn ◽  
Katarina Pavšič Vrtač ◽  
Tanja Knific ◽  
...  
Keyword(s):  
Seminal Plasma ◽  
Semen Quality ◽  
Sperm Quality ◽  
Membrane Integrity ◽  
Quality Characteristics ◽  
Freezing And Thawing ◽  
Additional Tool ◽  
Bull Semen ◽  
Bull Sperm ◽  
Fresh Semen

ABSTRACT Background Wide variation in fertility rates is observed when using frozen bull semen, even when the bulls have met quality standards for semen production. Therefore, a simple and reliable test to assess the freezing potential of bull semen based on the analysis of fresh semen or blood would be of great value. Attention is now turning to assessment of seminal plasma components such as proteins and elements. In the present study, the concentrations of macro- and microelements in fresh bull semen plasma and in serum and their correlation with quality characteristics of fresh semen and with semen quality after freezing and thawing were determined. Ejaculates were collected from 30 mature bulls, and semen volume, concentration, sperm motility, morphology, tail membrane integrity, plasma membrane permeability and DNA fragmentation were determined on the day of collection and after freezing and thawing. The concentrations of macroelements (Na, Mg, K and Ca) and microelements (Cu, Fe, Zn and Se) were determined in the seminal plasma and serum. The semen samples were classified into satisfactory and unsatisfactory groups according to the fresh semen quality. Results Zinc and Se levels measured in serum were associated with almost all fresh and frozen-thawed semen quality characteristics, while Fe levels were associated only with acrosomal defects in fresh semen. Zinc and Fe levels in fresh seminal plasma were associated with various quality characteristics of fresh and frozen-thawed semen, while Se level in fresh seminal plasma was not associated with any of the semen quality characteristics. Conclusions Microelements were shown to be useful as biomarkers involved in the analysis of bull sperm quality and could be used as an additional tool to predict bull semen quality after freezing and thawing. Our results confirm that the analysis of Zn and Se levels in serum and Zn, Cu and Fe levels in fresh seminal plasma can provide information to discriminate between bull semen samples with spermatozoa with high or low cryotolerance.

The assessment of sperm DNA fragmentation in the saltwater crocodile (Crocodylus porosus)

2017 ◽  
Vol 29 (3) ◽  
pp. 630 ◽  
Author(s):  
S. D. Johnston ◽  
C. López-Fernández ◽  
F. Arroyo ◽  
J. L. Fernández ◽  
J. Gosálvez
Keyword(s):  
Dna Damage ◽  
Dna Fragmentation ◽  
Sperm Chromatin ◽  
Sperm Dna Fragmentation ◽  
Fragmented Dna ◽  
Sperm Dna ◽  
Saltwater Crocodile ◽  
Crocodylus Porosus ◽  
Dispersion Test ◽  
Sperm Nuclei

Herein we report a method of assessing DNA fragmentation in the saltwater crocodile using the sperm chromatin dispersion test (SCDt) after including frozen–thawed spermatozoa in a microgel (Halomax; Halotech DNA, Madrid, Spain). Following controlled protein depletion, which included a reducing agent, sperm nuclei with fragmented DNA showed a homogeneous and larger halo of chromatin dispersion with a corresponding reduced nucleoid core compared with sperm with non-fragmented DNA. The presence of DNA damage was confirmed directly by incorporation of modified nucleotides using in situ nick translation (ISNT) and indirectly by studying the correlation of the SCDt with the results of DNA damage visualisation using a two-tailed comet assay (r = 0.90; P = 0.037). Results of the SCDt immediately following thawing and after 5 h incubation at 37°C in order to induce a range of DNA damage revealed individual crocodile differences in both the baseline level of DNA damage and DNA longevity.

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