Co-transcriptional Loading of RNA Export Factors Shapes the Human Transcriptome.

During gene expression, RNA export factors are mainly known for driving nucleo-cytoplasmic transport. While early studies suggested that the exon junction complex (EJC) provides a binding platform for them, subsequent work proposed that they are only recruited by the cap binding complex to the 5' end of RNAs, as part of TREX. Using iCLIP, we show that the export receptor Nxf1 and two TREX subunits, Alyref and Chtop, are recruited to the whole mRNA co-transcriptionally via splicing but before 3' end processing. Consequently, Alyref alters splicing decisions and Chtop regulates alternative polyadenylation. Alyref is recruited to the 5' end of RNAs by CBC, and our data reveal subsequent binding to RNAs near EJCs. We demonstrate that eIF4A3 stimulates Alyref deposition not only on spliced RNAs close to EJC sites but also on single-exon transcripts. Our study reveals mechanistic insights into the co-transcriptional recruitment of mRNA export factors and how this shapes the human transcriptome.

Comparing the development of cortex-wide gene expression patterns between two species in a common reference frame.

Advances in sequencing techniques have made comparative studies of gene expression a current focus for understanding evolutionary and developmental processes. However, insights into the spatial expression of genes have been limited by a lack of robust methodology. To overcome this obstacle, we developed methods and software tools for quantifying and comparing tissue-wide spatial patterns of gene expression within and between species. Here, we compare cortex-wide expression of RZRß and Id2 mRNA across early postnatal development in mice and voles. We show that patterns of RZRß expression in neocortical layer 4 are highly conserved between species but develop rapidly in voles and much more gradually in mice, who show a marked expansion in the relative size of the putative primary visual area across the first postnatal week. Patterns of Id2 expression, by contrast, emerge in a dynamic and layer-specific sequence that is consistent between the two species. We suggest that these differences in the development of neocortical patterning reflect the independent evolution of brains, bodies, and sensory systems in the 35 million years since their last common ancestor.

Project PRIME: road markings for motorcycle casualty reduction (an overview of findings from 2020 to 2022).

Pioneering road markings for motorcyclists, designed as Perceptual Rider Information for Maximising Expertise and Enjoyment (PRIMEs) were installed on approach to demanding bends at 22 trial sites and two comparison sites across the West Highlands of Scotland. The markings provided a series of 'gateways' to encourage safer riding. With 32,213 motorcyclists observed, the following statistically significant results were observed: speed reductions at 10 trial sites; positive changes in lateral position at the final PRIME gateway marking at 15 trial sites and positive changes in lateral position at the apex of the bend at 13 trial sites; reductions in braking at nine trial sites; increases use of PRIME road markings across 18 of the 22 trial sites. No statistically significant effects were observed at the comparison sites. These findings are discussed in relation to the 'Road Safety Framework to 2030' and the 'Safe System' approach to reducing motorcycle casualties.

This world-first research presents the largest investigation of rider behaviour involving 32,213 motorcyclists. Pioneering road markings for motorcyclists produced statistically significant positive behavioural changes in speed, lateral lane position and braking. This work identifies important behavioural factors that support the 'Safe System' approach to motorcycle casualty reduction.

Biological action at a distance: Correlated pattern formation in adjacent tessellation domains without communication.

Tessellations emerge in many natural systems, and the constituent domains often contain regular patterns, raising the intriguing possibility that pattern formation within adjacent domains might be correlated by the geometry, without the direct exchange of information between parts comprising either domain. We confirm this paradoxical effect, by simulating pattern formation via reaction-diffusion in domains whose boundary shapes tessellate, and showing that correlations between adjacent patterns are strong compared to controls that self-organize in domains with equivalent sizes but unrelated shapes. The effect holds in systems with linear and non-linear diffusive terms, and for boundary shapes derived from regular and irregular tessellations. Based on the prediction that correlations between adjacent patterns should be bimodally distributed, we develop methods for testing whether a given set of domain boundaries constrained pattern formation within those domains. We then confirm such a prediction by analysing the development of 'subbarrel' patterns, which are thought to emerge via reaction-diffusion, and whose enclosing borders form a Voronoi tessellation on the surface of the rodent somatosensory cortex. In more general terms, this result demonstrates how causal links can be established between the dynamical processes through which biological patterns emerge and the constraints that shape them.

Pilot Examination of the Efficacy of the Internet-Delivered, Preoperative, Preparation Program (I-PPP).

Limited evidence-based, interactive, Internet-delivered preoperative preparation programs for children and their parents exist. The purpose of this investigation was to compare the Internet-delivered, preoperative program (I-PPP) in alleviating anxiety in children undergoing outpatient surgery delivered alone (I-PPP) and in conjunction with parental presence (I-PPP + parent) to treatment as usual (TAU). 104 children undergoing day surgery procedures at a local hospital and their parents/guardians participated. Primary outcome measures: (a) observer-rated child anxiety and (b) induction compliance. Results demonstrated an interaction between the I-PPP and TAU groups over time, F(1, 64) = 5.11, p = .027, partial η p2 = .07. At anesthetic induction, the I-PPP group demonstrated lower observer-rated anxiety than TAU, F(1, 64) = 4.72, p = .034, η p2 = .07. I-PPP group demonstrated the best anesthesia induction compliance, F(1, 64) = 4.84, p = .031, η p2 = .07. Our findings demonstrate that the I-PPP is an efficacious preoperative preparation intervention for children. The 'real-world' uptake and integration of the I-PPP into pediatric preoperative settings require exploration going forward. Trial retrospectively registered March 2019 (Open Science Registration https://doi.org/10.17605/osf.io/2x8rg ).

Detecting SARS-CoV-2 at point of care: preliminary data comparing loop-mediated isothermal amplification (LAMP) to polymerase chain reaction (PCR).

BACKGROUND: A cost effective and efficient diagnostic tool for COVID-19 as near to the point of care (PoC) as possible would be a game changer in the current pandemic. We tested reverse transcription loop mediated isothermal amplification (RT-LAMP), a method which can produce results in under 30 min, alongside standard methods in a real-life clinical setting. METHODS: This prospective service improvement project piloted an RT-LAMP method on nasal and pharyngeal swabs on 21 residents of a high dependency care home, with two index COVID-19 cases, and compared it to multiplex tandem reverse transcription polymerase chain reaction (RT-PCR). We recorded vital signs of patients to correlate clinical and laboratory information and calculated the sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of a single swab using RT-LAMP compared with the current standard, RT-PCR, as per Standards for Reporting Diagnostic Accuracy Studies (STARD) guidelines. RESULTS: The novel method accurately detected 8/10 RT-PCR positive cases and identified a further 3 positive cases. Eight further cases were negative using both methods. Using repeated RT-PCR as a "gold standard", the sensitivity and specificity of a single novel test were 80 and 73% respectively. PPV was 73% and NPV was 83%. Incorporating retesting of low signal RT-LAMP positives improved the specificity to 100%. We also speculate that hypothermia may be a significant early clinical sign of COVID-19. CONCLUSIONS: RT-LAMP testing for SARS-CoV-2 was found to be promising, fast and to work equivalently to RT-PCR methods. RT-LAMP has the potential to transform COVID-19 detection, bringing rapid and accurate testing to the PoC. RT-LAMP could be deployed in mobile community testing units, care homes and hospitals to detect disease early and prevent spread.

Perceiving Social Cohesion: Movement Synchrony and Task Demands Both Matter.

Previous research has shown that interpersonal synchrony is associated with a number of prosocial effects. We investigated the respective roles of behavioural synchrony and perceived task demands on perceptions of cohesion by performing two experiments in which participants viewed pairs of point-light figures engaging in four coordinated behaviours. Behaviours were seen twice, once in perfect in-phase synchrony and once with synchrony manipulated (phase shift: 180° in Experiment 1 and 45°, 90°, 270°, and 315° in Experiment 2). Dyads were rated on perceived exertion and perceived social cohesion. Results indicate that in-phase synchrony is associated with higher levels of perceived cohesion and that perceived exertion is a good predictor of cohesion ratings. Two interactions suggest that the effect is not purely perceptual and that participants observing coordinated movement also make inferences about the intentions of those observed. Results are discussed and future directions suggested.

Polymer-Ligand-Based ELISA for Robust, High-Throughput, Quantitative Detection of p53 Aggregates.

A growing number of diseases are being linked to protein misfolding and amyloid formation. Recently, p53 was also shown to associate into amyloid aggregates, raising the question of whether cancer development is associated with protein aggregation as well. However, a lack of suitable tools has hampered the evaluation of their clinical relevance. Herein, we report an enzyme-linked-immunosorbent-assay (ELISA) system based on a polyionic, high-molecular-weight ligand that specifically captures aggregated oligomers and amyloid proteins. We proved that naturally occurring tetramers of p53 are not bound, but high-molecular-weight aggregates are bound and subsequently detected. For the first time, this assay allows the quantitative detection of p53 aggregates from cell lysates, which was demonstrated using 22 ovarian-cancer cell lines as well as 7 patient-derived tumor tissues. The levels of p53 aggregates within the missense-mutated tissue samples varied more than 12-fold. This simple, robust method allows studying the abundance and clinical relevance of protein aggregates. This could help our understanding of the role of protein misfolding in cancer or even in predicting therapy responses to aggregation-targeting drugs.

Self-organised criticality in the evolution of a thermodynamic model of rodent thermoregulatory huddling.

A thermodynamic model of thermoregulatory huddling interactions between endotherms is developed. The model is presented as a Monte Carlo algorithm in which animals are iteratively exchanged between groups, with a probability of exchanging groups defined in terms of the temperature of the environment and the body temperatures of the animals. The temperature-dependent exchange of animals between groups is shown to reproduce a second-order critical phase transition, i.e., a smooth switch to huddling when the environment gets colder, as measured in recent experiments. A peak in the rate at which group sizes change, referred to as pup flow, is predicted at the critical temperature of the phase transition, consistent with a thermodynamic description of huddling, and with a description of the huddle as a self-organising system. The model was subjected to a simple evolutionary procedure, by iteratively substituting the physiologies of individuals that fail to balance the costs of thermoregulation (by huddling in groups) with the costs of thermogenesis (by contributing heat). The resulting tension between cooperative and competitive interactions was found to generate a phenomenon called self-organised criticality, as evidenced by the emergence of avalanches in fitness that propagate across many generations. The emergence of avalanches reveals how huddling can introduce correlations in fitness between individuals and thereby constrain evolutionary dynamics. Finally, a full agent-based model of huddling interactions is also shown to generate criticality when subjected to the same evolutionary pressures. The agent-based model is related to the Monte Carlo model in the way that a Vicsek model is related to an Ising model in statistical physics. Huddling therefore presents an opportunity to use thermodynamic theory to study an emergent adaptive animal behaviour. In more general terms, huddling is proposed as an ideal system for investigating the interaction between self-organisation and natural selection empirically.

Rapid response team calls to obstetric patients in a busy quaternary maternity hospital.

AIMS: There is limited published information regarding intensive care unit (ICU) led rapid response team (RRT) calls to obstetric patients. We examined the characteristics of RRT calls to obstetric patients at a tertiary teaching hospital. METHODS: Details of calls to pregnant and postpartum patients between October 2010 and June 2014 were obtained from the hospital RRT database. Each was retrospectively examined for data on patient demographics, call trigger, interventions and outcomes. Local obstetric-specific escalation practices (Code Pink/Green) for obstetrical concerns (not mandating maternal instability/involvement of the ICU team), were excluded. RESULTS: There were 106 RRT calls logged during 43 months, and 97 had data available for analysis. Women currently pregnant accounted for 33% of calls and postpartum women 67%, with nearly half of these occurring more than 24 h post-delivery. The most common reason (29% of calls) for calling the RRT was hypotension, followed by 'concern about patient' (21%) and decreased Glasgow Coma Score (GCS) (17%). An escalation in the environment of care occurred after 32% of calls, with approximately 11% of calls necessitating direct ICU admission. Twenty-three percent of all calls were to women who had an ICU admission during their hospital stay. Among the cohort who received an RRT call, there was one maternal and three neonatal deaths. CONCLUSION: At our institution generic RRT calls are called to both pregnant and postpartum women, and frequently result in an escalation in the care environment. Further study is required to understand better the specific needs of this important population.

ATP is required for interactions between UAP56 and two conserved mRNA export proteins, Aly and CIP29, to assemble the TREX complex.

The conserved TREX mRNA export complex is known to contain UAP56, Aly, Tex1, and the THO complex. Here, we carried out proteomic analysis of immunopurified human TREX complex and identified the protein CIP29 as the only new component with a clear yeast relative (known as Tho1). Tho1 is known to function in mRNA export, and we provide evidence that CIP29 likewise functions in this process. Like the known TREX components, a portion of CIP29 localizes in nuclear speckle domains, and its efficient recruitment to mRNA is both splicing- and cap-dependent. We show that UAP56 mediates an ATP-dependent interaction between the THO complex and both CIP29 and Aly, indicating that TREX assembly is ATP-dependent. Using recombinant proteins expressed in Escherichia coli, we show that UAP56, Aly, and CIP29 form an ATP-dependent trimeric complex, and UAP56 bridges the interaction between CIP29 and Aly. We conclude that the interaction of two conserved export proteins, CIP29 and Aly, with UAP56 is strictly regulated by ATP during assembly of the TREX complex.

Chtop is a component of the dynamic TREX mRNA export complex.

The TREX complex couples nuclear pre-mRNA processing with mRNA export and contains multiple protein components, including Uap56, Alyref, Cip29 and the multi-subunit THO complex. Here, we have identified Chtop as a novel TREX component. We show that both Chtop and Alyref activate the ATPase and RNA helicase activities of Uap56 and that Uap56 functions to recruit both Alyref and Chtop onto mRNA. As observed with the THO complex subunit Thoc5, Chtop binds to the NTF2-like domain of Nxf1, and this interaction requires arginine methylation of Chtop. Using RNAi, we show that co-knockdown of Alyref and Chtop results in a potent mRNA export block. Chtop binds to Uap56 in a mutually exclusive manner with Alyref, and Chtop binds to Nxf1 in a mutually exclusive manner with Thoc5. However, Chtop, Thoc5 and Nxf1 exist in a single complex in vivo. Together, our data indicate that TREX and Nxf1 undergo dynamic remodelling, driven by the ATPase cycle of Uap56 and post-translational modifications of Chtop.

Arginine methylation and citrullination of splicing factor proline- and glutamine-rich (SFPQ/PSF) regulates its association with mRNA.

Splicing factor proline- and glutamine-rich (SFPQ) also commonly known as polypyrimidine tract-binding protein-associated-splicing factor (PSF) and its binding partner non-POU domain-containing octamer-binding protein (NONO/p54nrb), are highly abundant, multifunctional nuclear proteins. However, the exact role of this complex is yet to be determined. Following purification of the endogeneous SFPQ/NONO complex, mass spectrometry analysis identified a wide range of interacting proteins, including those involved in RNA processing, RNA splicing, and transcriptional regulation, consistent with a multifunctional role for SFPQ/NONO. In addition, we have identified several sites of arginine methylation in SFPQ/PSF using mass spectrometry and found that several arginines in the N-terminal domain of SFPQ/PSF are asymmetrically dimethylated. Furthermore, we find that the protein arginine N-methyltransferase, PRMT1, catalyzes this methylation in vitro and that this is antagonized by citrullination of SFPQ. Arginine methylation and citrullination of SFPQ/PSF does not affect complex formation with NONO. However, arginine methylation was shown to increase the association with mRNA in mRNP complexes in mammalian cells. Finally we show that the biochemical properties of the endogenous complex from cell lysates are significantly influenced by the ionic strength during purification. At low ionic strength, the SFPQ/NONO complex forms large heterogeneous protein assemblies or aggregates, preventing the purification of the SFPQ/NONO complex. The ability of the SFPQ/NONO complex to form varying protein assemblies, in conjunction with the effect of post-translational modifications of SFPQ modulating mRNA binding, suggests key roles affecting mRNP dynamics within the cell.

Using parathyroid hormone spikes during parathyroidectomy to guide intraoperative decision-making.

BACKGROUND: Intraoperative parathyroid hormone (IOPTH) level monitoring is a useful adjunct to parathyroidectomy for primary hyperparathyroidism (pHPT). Occasionally, increases ("spikes") in IOPTH levels from the preoperative baseline parathyroid hormone may occur, which may lead to longer operative times or more extensive neck exploration or both. The aim of this study was to determine if the extent of IOPTH level increase predicts single gland disease (SGD). METHODS: This is a retrospective review of a prospective parathyroid database of patients undergoing parathyroidectomy for sporadic pHPT from 1999-2013. Extent of parathyroid hormone spike was calculated by the difference in IOPTH level at the time of gland excision and baseline: group 1 had a decrease in IOPTH level, group 2 had IOPTH level increase one to three times above the baseline, and group 3 had IOPTH level increase greater than three times above the baseline. RESULTS: Of the 900 patients in the cohort, there were 634 patients (70%) in group 1, 234 (26%) in group 2, and 32 (4%) in group 3. SGD was identified in 88%, 78%, and 100% of patients in groups 1, 2, and 3, respectively. The median gland weight in group 3 (920 mg) was significantly larger than those in groups 1 and 2 (440 and 460 mg, respectively; P < 0.001). CONCLUSIONS: IOPTH level spikes occur in nearly one-third of patients undergoing parathyroidectomy for sporadic pHPT. Patients with extensive IOPTH level increase are more likely to have larger SGD, whereas patients with moderate IOPTH level increases have increased incidence of multigland disease. In patients with a significant increase in IOPTH levels and larger glands, no further surgical exploration may be indicated.

Concurrent endocrine and other surgical procedures: an institutional experience.

INRODUCTION: The number of endocrine procedures, specifically parathyroidectomy, thyroidectomy, and adrenalectomy, being performed is increasing. There is a paucity of literature on the feasibility of combining these procedures with other surgical procedures. Therefore, the aim of this study was to determine the effect of performing concurrent surgical procedures on postoperative outcomes. METHODS: This is a single institution retrospective review of multiple prospectively maintained databases of patients who underwent elective thyroidectomy, parathyroidectomy, and/or adrenalectomy in combination with another procedure. The other procedures included soft tissue, breast or hernia, abdominal major, abdominal minor, cervical, and "other". Demographics, operative details, length-of-stay, and 30-d outcomes were reviewed. "Endocrine-specific" complications included recurrent laryngeal nerve injury, hypoparathyroidism, cervical wound infection, hematoma, and other. RESULTS: The cohort comprised 104 patients. Overall, 19 (18%) patients had 21 complications, including endocrine-specific complications in eleven (11%) patients. These eleven complications included recurrent laryngeal nerve injury (n = 3; 3%), hematoma (n = 2; 2%), wound infection (n = 1; 1%), transient hypoparathyroidism (n = 2; 2%), and other (n = 3; 3%). The remaining complications included three (3%) general complications, six (6%) patients with complications related to the concurrent procedure, and one patient who underwent an open adrenalectomy and hysterectomy and developed a midline wound dehiscence, which could not be specifically attributed to either procedure. CONCLUSIONS: Less than 5% of patients undergoing a surgical endocrine procedure underwent a concurrent procedure, ranging from soft tissue to major abdominal. Short-term endocrine-specific complications were managed safely, suggesting that concurrent procedures can be considered, with minimal effect on patient outcomes.

The role of TREX in gene expression and disease.

TRanscription and EXport (TREX) is a conserved multisubunit complex essential for embryogenesis, organogenesis and cellular differentiation throughout life. By linking transcription, mRNA processing and export together, it exerts a physiologically vital role in the gene expression pathway. In addition, this complex prevents DNA damage and regulates the cell cycle by ensuring optimal gene expression. As the extent of TREX activity in viral infections, amyotrophic lateral sclerosis and cancer emerges, the need for a greater understanding of TREX function becomes evident. A complete elucidation of the composition, function and interactions of the complex will provide the framework for understanding the molecular basis for a variety of diseases. This review details the known composition of TREX, how it is regulated and its cellular functions with an emphasis on mammalian systems.

Luzp4 defines a new mRNA export pathway in cancer cells.

Cancer testis antigens (CTAs) represented a poorly characterized group of proteins whose expression is normally restricted to testis but are frequently up-regulated in cancer cells. Here we show that one CTA, Luzp4, is an mRNA export adaptor. It associates with the TREX mRNA export complex subunit Uap56 and harbours a Uap56 binding motif, conserved in other mRNA export adaptors. Luzp4 binds the principal mRNA export receptor Nxf1, enhances its RNA binding activity and complements Alyref knockdown in vivo. Whilst Luzp4 is up-regulated in a range of tumours, it appears preferentially expressed in melanoma cells where it is required for growth.

Competitive and cooperative interactions mediate RNA transfer from herpesvirus saimiri ORF57 to the mammalian export adaptor ALYREF.

The essential herpesvirus adaptor protein HVS ORF57, which has homologs in all other herpesviruses, promotes viral mRNA export by utilizing the cellular mRNA export machinery. ORF57 protein specifically recognizes viral mRNA transcripts, and binds to proteins of the cellular transcription-export (TREX) complex, in particular ALYREF. This interaction introduces viral mRNA to the NXF1 pathway, subsequently directing it to the nuclear pore for export to the cytoplasm. Here we have used a range of techniques to reveal the sites for direct contact between RNA and ORF57 in the absence and presence of ALYREF. A binding site within ORF57 was characterized which recognizes specific viral mRNA motifs. When ALYREF is present, part of this ORF57 RNA binding site, composed of an α-helix, binds preferentially to ALYREF. This competitively displaces viral RNA from the α-helix, but contact with RNA is still maintained by a flanking region. At the same time, the flexible N-terminal domain of ALYREF comes into contact with the viral RNA, which becomes engaged in an extensive network of synergistic interactions with both ALYREF and ORF57. Transfer of RNA to ALYREF in the ternary complex, and involvement of individual ORF57 residues in RNA recognition, were confirmed by UV cross-linking and mutagenesis. The atomic-resolution structure of the ORF57-ALYREF interface was determined, which noticeably differed from the homologous ICP27-ALYREF structure. Together, the data provides the first site-specific description of how viral mRNA is locked by a herpes viral adaptor protein in complex with cellular ALYREF, giving herpesvirus access to the cellular mRNA export machinery. The NMR strategy used may be more generally applicable to the study of fuzzy protein-protein-RNA complexes which involve flexible polypeptide regions.

Depolarization of sperm membrane potential is a common feature of men with subfertility and is associated with low fertilization rate at IVF.

STUDY QUESTION: Are significant abnormalities in outward (K(+)) conductance and resting membrane potential (Vm) present in the spermatozoa of patients undertaking IVF and ICSI and if so, what is their functional effect on fertilization success? SUMMARY ANSWER: Negligible outward conductance (≈5% of patients) or an enhanced inward conductance (≈4% of patients), both of which caused depolarization of Vm, were associated with a low rate of fertilization following IVF. WHAT IS KNOWN ALREADY: Sperm-specific potassium channel knockout mice are infertile with defects in sperm function, suggesting that these channels are essential for fertility. These observations suggest that malfunction of K(+) channels in human spermatozoa might contribute significantly to the occurrence of subfertility in men. However, remarkably little is known of the nature of K(+) channels in human spermatozoa or the incidence and functional consequences of K(+) channel defects. STUDY DESIGN, SIZE AND DURATION: Spermatozoa were obtained from healthy volunteer research donors and subfertile IVF and ICSI patients attending a hospital assisted reproductive techniques clinic between May 2013 and December 2015. In total, 40 IVF patients, 41 ICSI patients and 26 normozoospermic donors took part in the study. PARTICIPANTS/MATERIALS, SETTING, METHODS: Samples were examined using electrophysiology (whole-cell patch clamping). Where abnormal electrophysiological characteristics were identified, spermatozoa were further examined for Ca(2+) influx induced by progesterone and penetration into viscous media if sufficient sample was available. Full exome sequencing was performed to specifically evaluate potassium calcium-activated channel subfamily M α 1 (KCNMA1), potassium calcium-activated channel subfamily U member 1 (KCNU1) and leucine-rich repeat containing 52 (LRRC52) genes and others associated with K(+) signalling. In IVF patients, comparison with fertilization rates was done to assess the functional significance of the electrophysiological abnormalities. MAIN RESULTS AND THE ROLE OF CHANCE: Patch clamp electrophysiology was used to assess outward (K(+)) conductance and resting membrane potential (Vm) and signalling/motility assays were used to assess functional characteristics of sperm from IVF and ICSI patient samples. The mean Vm and outward membrane conductance in sperm from IVF and ICSI patients were not significantly different from those of control (donor) sperm prepared under the same conditions, but variation between individuals was significantly greater (P< 0.02) with a large number of outliers (>25%). In particular, in ≈10% of patients (7/81), we observed either a negligible outward conductance (4 patients) or an enhanced inward current (3 patients), both of which caused depolarization of Vm. Analysis of clinical data from the IVF patients showed significant association of depolarized Vm (≥0 mV) with low fertilization rate (P= 0.012). Spermatozoa with electrophysiological abnormities (conductance and Vm) responded normally to progesterone with elevation of [Ca(2+)]i and penetration of viscous medium, indicating retention of cation channel of sperm (CatSper) channel function. LIMITATIONS, REASONS FOR CAUTION: For practical, technical, ethical and logistical reasons, we could not obtain sufficient additional semen samples from men with conductance abnormalities to establish the cause of the conductance defects. Full exome sequencing was only available in two men with conductance defects. WIDER IMPLICATIONS OF THE FINDINGS: These data add significantly to the understanding of the role of ion channels in human sperm function and its impact on male fertility. Impaired potassium channel conductance (Gm) and/or Vm regulation is both common and complex in human spermatozoa and importantly is associated with impaired fertilization capacity when the Vm of cells is completely depolarized. STUDY FUNDING/COMPETING INTERESTS: The majority of the data were obtained using funding from MRC project grants (#MR/K013343/1, MR/012492/1). Additional funding was provided by NHS Tayside, TENOVUS, Chief Scientist Office NRS Fellowship and University of Abertay. The authors declare that there is no conflict of interest. TRIAL REGISTRATION NUMBER: Not applicable.