Robert John Aitken

The University of Newcastle, Australia · Department of Biological Sciences

Anthropogenic chemical pollution has the potential to pose one of the largest environmental threats to humanity, but global understanding of the issue remains fragmented. This article presents a comprehensive perspective of the threat of chemical pollution to humanity, emphasising male fertility, cognitive health and food security. There are seriou...

Background The seminal vesicles synthesise bioactive factors that support gamete function, modulate the female reproductive tract to promote implantation, and influence developmental programming of offspring phenotype. Despite the significance of the seminal vesicles in reproduction, their biology remains poorly defined. Here, to advance understand...

Stallion sperm membranes comprise a high proportion of polyunsaturated fatty acids, making stallion spermatozoa especially vulnerable to peroxidative damage from reactive oxygen species generated as a by-product of cell metabolism. Membrane lipid replacement therapy with glycerophospholipid (GPL) mixtures has been shown to reduce oxidative damage i...

The world was first alerted to the existence of a novel coronavirus (COVID-19) on December 31st, 2019. In the 2 years that have elapsed since the beginning of this outbreak, sporadic reports have emerged of an impact on male reproductive health. It is now timely to look at this information to see what conclusions can be drawn. The evidence collecte...

Seminal vesicles are an integral part of the male reproductive accessory gland system. They produce a complex array of secretions containing bioactive constituents that support gamete function and promote reproductive success, with emerging evidence suggesting these secretions are influenced by our environment. Despite their significance, the biolo...

Assessments of sperm DNA damage are controversial because of perceived uncertainties over the relationship with pregnancy and the limited range of therapies available should positive results be returned. In this article, we highlight recent data supporting a chain of associations between oxidative stress in the male germ line, DNA damage in spermat...

Evidence is presented for expression of the insulin receptor on the surface of mammalian spermatozoa as well as transcripts for the receptor substrate adaptor proteins (IRS1-4) needed to mediate insulin action. Exposure to this hormone resulted in insulin receptor phosphorylation (pTyr972), activation of AKT (pSer473) and the stimulation of sperm m...

Oxidative stress generates a large amount of reactive oxygen species (ROS) and affects sperm quality via damaging sperm DNA and compromising the intracellular homeostasis in human spermatozoa. In assisted reproductive technology (ART), it is substantial to prevent spermatozoa from ROS attack. The pineal hormone melatonin has the natural antioxidant...

A prevalent cause of sperm dysfunction in male infertility patients is the overproduction of reactive oxygen species, an attendant increase in lipid peroxidation and the production of cytotoxic reactive carbonyl species such as 4-hydroxynonenal. Our previous studies have implicated arachidonate 15-lipoxygenase (ALOX15) in the production of 4-hydrox...

Due to their antimicrobial activity, parabens are commonly used as preservatives in a variety of consumer goods- including cosmetics, pharmaceuticals, and personal care products. During the production, usage and disposal of these products, parabens are released into the environment. In this study, the persistence of three widely used parabens; meth...

Spermatogonial stem cells (SSCs) are generally characterized by excellent DNA surveillance and repair, resulting in one of the lowest spontaneous mutation rates in the body. However, the barriers to mutagenesis can be overwhelmed under two sets of circumstances. First, replication errors may generate age-dependent mutations that provide the mutant...

Male infertility is recognized as a relatively common, complex condition, generated by a broad array of environmental and genetic factors. Historical reliance on the conventional semen profile has tended to underestimate the true contribution of “the male factor” to human infertility. This review highlights the importance of genetic and epigenetic...

A novel strategy intended for sterilization of domestic animals centered on the use of a chemically modified M13 bacteriophage to effect the targeted delivery of menadione, a redox-cycling naphthoquinone. An M13 random peptide ‘phage display was used to pan against mouse gonocytes to isolate gonocyte-specific targeting clones. One such clone was ch...

DNA damage is a common feature of human spermatozoa associated with an impaired capacity to fertilize the oocyte and an increased mutational load in the offspring. However, the etiology of this damage remains poorly defined. In this study we demonstrate that a major pathway for the induction of DNA damage in mammalian spermatozoa is triggered by ex...

Despite the high prevalence of male infertility, very little is known about its etiology. In recent years however, advances in gene sequencing technology have enabled us to identify a large number of rare single point mutations responsible for impeding all aspects of male reproduction from its embryonic origins, through the endocrine regulation of...

The horse breeding industry relies upon optimal stallion fertility. Conventional sperm assessments provide limited information regarding ejaculate quality and are not individually predictive of fertilising potential. The aim of this study was to harness mass spectrometry to compare the proteomic profiles of high- and low-quality stallion spermatozo...

The COVID‐19 (SARS‐CoV‐2) virus has created a global pandemic responsible for over 500,000 deaths and untold human and economic suffering. Attention has rightly focused on the respiratory system, because this is where a life‐and‐death battle is waged between the viral horde and the host’s immune system. However, other tissues are also susceptible t...

MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] is widely used in biology as a probe for cell viability by virtue of its ability to generate deposits of insoluble formazan at sites of intense oxidoreductase activity. This response is generally held to reflect mitochondrial redox activity, however extra-mitochondrial MTT reduction...

Male and Sperm Factors that Maximize IVF Success - edited by John Aitken April 2020

Reactive oxygen species (ROS) are implicated in all aspects of cellular functions. While the importance of as ROS signalling molecules is well described, ROS are also associated with stress pathologies. Within the reproduction field, there are associations with reduced fertility as a result of lipid peroxidation, protein dysfunction, premature cell...

This article addresses the importance of oxidative processes in both the generation of functional gametes and the aetiology of defective sperm function. Functionally, sperm capacitation is recognized as a redox-regulated process, wherein a low level of reactive oxygen species (ROS) generation is intimately involved in driving such events as the sti...

Sperm cells have long been known to be good producers of reactive oxygen species, while they are also known to be particularly sensitive to oxidative damage affecting their structures and functions. As with all organic cellular components, sperm nuclear components and, in particular, nucleic acids undergo oxidative alterations that have recently be...

Male and female germ lines are vulnerable to oxidative stress. In spermatozoa, such stress triggers a lipid peroxidation cascade that culminates in the generation of electrophilic lipid aldehydes that bind to DNA and a raft of proteins involved in the delivery of functionally competent cells. One set of targets for these aldehydes are the proteins...

Artificially generated radiofrequency-electromagnetic energy (RF-EME) is now ubiquitous in our environment owing to the utilization of mobile phone and Wi-Fi based communication devices. While several studies have revealed that RF-EME is capable of eliciting biological stress, particularly in the context of the male reproductive system, the mechani...

Background: The sperm protein IZUMO1 (Izumo sperm-egg fusion 1) and its recently identified binding partner on the oolemma, IZUMO1R, are among the first ligand-receptor pairs shown to be essential for gamete recognition and adhesion. However, the IZUMO1-IZUMO1R interaction does not appear to be directly responsible for promoting the fusion of the...

Study question: Do all regions of the paternal genome within the gamete display equivalent vulnerability to oxidative DNA damage? Summary answer: Oxidative DNA damage is not randomly distributed in mature human spermatozoa but is instead targeted, with particular chromosomes being especially vulnerable to oxidative stress. What is known already...

Background: A defining feature of sexual reproduction is the transmission of genomic information from both parents to the offspring. There is now compelling evidence that the inheritance of such genetic information is accompanied by additional epigenetic marks, or stable heritable information that is not accounted for by variations in DNA sequence...

Male fertility and sperm quality are negatively impacted by obesity. Furthermore, recent evidence has shown that male offspring from obese rat mothers also have reduced sperm quality and fertility. Here, we extend work in this area by comparing the effects of both maternal obesity and offspring post-weaning diet-induced obesity, as well as their co...

Due to its particular “silent” metabolic state, without transcription or translation, and a low level of cytosolic protective activities, mature sperm is a cellular type of aerobic organisms particularly at risk of oxidative damage. Despite the efforts of the male genital tract to treat this problem, a subcellular compartment of the sperm, the nucl...

By virtue of its ability to rapidly isolate spermatozoa with good morphology and low levels of DNA fragmentation, electrophoretic sperm separation promises to be an extremely versatile, time-saving and efficient method for preparing spermatozoa for a wide variety of applications in assisted reproduction.

More than 1,000 genes are predicted to be predominantly expressed in mouse testis, yet many of them remain unstudied in terms of their roles in spermatogenesis and sperm function and their essentiality in male reproduction. Since individually indispensable factors can provide important implications for the diagnosis of genetically-related idiopathi...

Oxidative stress is a major aetiology in many pathologies, including that of male infertility. Recent evidence in somatic cells has linked oxidative stress to the induction of a novel cell death modality termed ferroptosis. However, the induction of this iron-regulated, caspase-independent cell death pathway has never been explored outside of the s...

Stallions experience lower per cycle conception rates compared to other livestock species, largely because they are selected for breeding based on athletic prowess and not reproductive fitness. Mares are seasonal breeders, and pregnancies cannot be detected until 10-14 days post-cover via transrectal ultrasonography. This means the detection of sta...

Background: DNA integrity and stability are critical determinants of cell viability. This is especially true in the female germline, wherein DNA integrity underpins successful conception, embryonic development, pregnancy and the production of healthy offspring. However, DNA is not inert; rather, it is subject to assault from various environment fa...

Diabetes is associated with poor oocyte quality and the dysregulation of ovarian function and is thus a leading contributor to the increasing prevalence of female reproductive pathologies. Accordingly, it is well-established that insulin fulfils a key role in the regulation of several facets of female reproduction. What remains less certain is whet...

Background and Objectives Serine proteases are emerging as important players in the spermatozoon's acquisition of functional competence. This study aimed to characterize the serine protease testisin (PRSS21) in stallion spermatozoa, examining its surface expression, possible origins in the testis and epididymis, and changes in response to capacitat...

We hypothesized that thiols and particularly glutathione (GSH) are essential for the regulation of stallion sperm functionality. To test this hypothesis, we initially investigated the relationship between sperm function and GSH content, revealing highly significant correlations between GSH, sperm viability, motility, and velocity parameters (P < 0....

An increase in oxidative protein damage is a leading contributor to age-associated decline in oocyte quality. By removing such damaged proteins, the proteasome plays an essential role in maintaining the fidelity of oocyte meiosis. In this study, we established that decreased proteasome activity in naturally aged, germinal vesicle (GV) mouse oocytes...

Cell viability under RF-EMR exposure. Associated viability counts were performed for all cell types exposed to RF-EMR treatment. (A) GC1, (B) GC2, (C) spermatogonia, (D) HEK293, (E) COV434, and (F) McCoy cells exposed to 0.15 W/kg RF-EMR (top box). (G) GC1, (H) GC2, and (I) spermatozoa exposed to 1.5 W/kg RF-EMR (bottom box).

Examination of the effect of exposing male germ cells and spermatozoa to an elevated dose of RF-EMR. The studies reported in Figure 1 of this manuscript were replicated on (A) GC1 (B) GC2 cell lines and (C) spermatozoa exposed to an elevated intensity of RF-EMR (1.5 W/kg). Mitochondrial ROS generation in both germ cell populations and spermatozoa w...

As the use of mobile phone devices is now highly prevalent, many studies have sought to evaluate the effects of the radiofrequency-electromagnetic radiation (RF-EMR) on both human health and biology. While several such studies have shown RF-EMR is capable of inducing cellular stress, the physicobiological origin of this stress remains largely unres...

Absolute infertility in the stallion can be a source of great frustration and significant financial loss across all sectors of the equine breeding industry. Where motile and morphologically normal spermatozoa are present in the ejaculate, and infertility cannot be overcome by artificial insemination, the clinician is left with few options for furth...

The unique biology of the oocyte means that accepted paradigms for DNA repair and protection are not of direct relevance to the female gamete. Instead, preservation of the integrity of the maternal genome depends on endogenous protein stores and/or mRNA transcripts accumulated during oogenesis. The aim of this study was to determine whether mature...

The Big Blue® λSelect-cII selection system has been employed along with whole-exome sequencing, to examine the susceptibility of the male germ line to mutation in two challenging situations: (i) exposure to a chemotherapeutic regime including bleomycin, etoposide and cis-platinum (BEP) and (ii) the ageing process. A 3-week exposure to BEP induced c...

The purpose of this article is to theoretically explore men’s preconception health as a mechanism to enhance fertility, as well as the health and well-being of the subject and his descendants. Premorbid risk factors and behaviors associated with stress, environmental toxins, excessive alcohol consumption, smoking, lack of exercise/obesity, and the...

Parabens are used as antimicrobial preservative agent in many commercial products including cosmetics and pharmaceuticals. Weak oestrogenic and antiandrogenic activities have been attributed to parabens in in vitro and in vivo studies. In this study, human spermatozoa were exposed to different concentrations of an equimolar paraben mixture containi...

Study question: Can a discriminant threshold be determined for human sperm DNA oxidation? Summary answer: A discriminant threshold was found with 65.8% of 8-hydroxy-2'-deoxyguanosine (8-OHdG)-positive sperm cells and a mean intensity of fluorescence (MIF) of 552 arbitrary units. What is known already: Oxidative stress is known to interfere wit...

Current approaches for DNA extraction and fragmentation from mammalian spermatozoa provide several challenges for the investigation of the oxidative stress burden carried in the genome of male gametes. Indeed, the potential introduction of oxidative DNA damage induced by reactive oxygen species, reducing agents (dithiothreitol or beta-mercaptoethan...

coverage.pl. Perl script constructed to calculate the read coverage by comparing the alignment positions of mapped reads against the human reference genome (GRCh38/hg39). Accuracy of the read alignment programs bowtie and bowtie 2 assessed from depth of coverage of individual base pairs. (DOCX)

parse_bowtie_alignments.pl. Perl script constructed to read and extract the mapped location of each read to the human reference genome (GRCh38/hg39), the read reference name and nucleotide sequence form the output files generated by the read alignment programs bowtie and bowtie 2. (DOCX)

clean_backgroundNoise.pl. Perl algorithm developed to remove DNA sequences classified as background noise found in negative control samples from samples containing oxidised DNA fragments extracted by antibody during the MoDIP protocol. Script generates two files, one containing the all sequences without background noise and the other with all the r...

clusterMaker.pl. Perl algorithm created to sort the mapped sequences of DNA from samples and group overlapping ones into clusters of continuous reads. The algorithm first sorts the reads by chromosome and location and then based on start and end positions of consecutive reads dynamically aggregate them into clusters. Script includes the option of a...

This article is a personal perspective on male infertility, a condition that is not only extremely prevalent but also a major reason for couples to resort to assisted reproductive technology. The introduction of intra-cytoplasmic sperm injection (ICSI) as a form of facilitated fertilization had a revolutionary impact on our capacity to treat cases...

One of the leading causes of male infertility is defective sperm function, a pathology that commonly arises from oxidative stress in the germline. Lipid peroxidation events in the sperm plasma membrane result in the generation of cytotoxic aldehydes such as 4-hydroxynonenal (4HNE), which accentuate the production of reactive oxygen species (ROS) an...

The reproductive consequences of global warming are not currently understood. In order to address this issue we have examined the reproductive consequences of exposing male mice to a mild heat stress. For this purpose, adult male mice were exposed to an elevated ambient temperature of 35°C under two exposure models. The first involved acute exposur...

Novel technological innovations in high-resolution mass spectrometry have ushered in a new era in proteomic analyses. Coupled with enhanced methods for cellular and protein pre-fractionation, such developments have enabled the detailed characterization of proteomes from various cell types, including the spermatozoa of a number of species. Collectiv...

Nuclear DNA damage in spermatozoa could potentially have a major impact on the fertilizing capacity of these cells, their ability to establish a normal pattern of embryonic development as well as the health and wellbeing of subsequent offspring. Many laboratory techniques have been developed to assess this damage focusing on strand breaks, chromati...