Hybrid Gene Origination Creates Human-Virus Chimeric Proteins during Infection.

RNA viruses are a major human health threat. The life cycles of many highly pathogenic RNA viruses like influenza A virus (IAV) and Lassa virus depends on host mRNA, because viral polymerases cleave 5'-m7G-capped host transcripts to prime viral mRNA synthesis ("cap-snatching"). We hypothesized that start codons within cap-snatched host transcripts could generate chimeric human-viral mRNAs with coding potential. We report the existence of this mechanism of gene origination, which we named "start-snatching." Depending on the reading frame, start-snatching allows the translation of host and viral "untranslated regions" (UTRs) to create N-terminally extended viral proteins or entirely novel polypeptides by genetic overprinting. We show that both types of chimeric proteins are made in IAV-infected cells, generate T cell responses, and contribute to virulence. Our results indicate that during infection with IAV, and likely a multitude of other human, animal and plant viruses, a host-dependent mechanism allows the genesis of hybrid genes.

Conserved 5-methyluridine tRNA modification modulates ribosome translocation.

While the centrality of posttranscriptional modifications to RNA biology has long been acknowledged, the function of the vast majority of modified sites remains to be discovered. Illustrative of this, there is not yet a discrete biological role assigned for one of the most highly conserved modifications, 5-methyluridine at position 54 in tRNAs (m5U54). Here, we uncover contributions of m5U54 to both tRNA maturation and protein synthesis. Our mass spectrometry analyses demonstrate that cells lacking the enzyme that installs m5U in the T-loop (TrmA in Escherichia coli, Trm2 in Saccharomyces cerevisiae) exhibit altered tRNA modification patterns. Furthermore, m5U54-deficient tRNAs are desensitized to small molecules that prevent translocation in vitro. This finding is consistent with our observations that relative to wild-type cells, trm2Δ cell growth and transcriptome-wide gene expression are less perturbed by translocation inhibitors. Together our data suggest a model in which m5U54 acts as an important modulator of tRNA maturation and translocation of the ribosome during protein synthesis.

More than one million barriers fragment Europe's rivers.

Rivers support some of Earth's richest biodiversity1 and provide essential ecosystem services to society2, but they are often fragmented by barriers to free flow3. In Europe, attempts to quantify river connectivity have been hampered by the absence of a harmonized barrier database. Here we show that there are at least 1.2 million instream barriers in 36 European countries (with a mean density of 0.74 barriers per kilometre), 68 per cent of which are structures less than two metres in height that are often overlooked. Standardized walkover surveys along 2,715 kilometres of stream length for 147 rivers indicate that existing records underestimate barrier numbers by about 61 per cent. The highest barrier densities occur in the heavily modified rivers of central Europe and the lowest barrier densities occur in the most remote, sparsely populated alpine areas. Across Europe, the main predictors of barrier density are agricultural pressure, density of river-road crossings, extent of surface water and elevation. Relatively unfragmented rivers are still found in the Balkans, the Baltic states and parts of Scandinavia and southern Europe, but these require urgent protection from proposed dam developments. Our findings could inform the implementation of the EU Biodiversity Strategy, which aims to reconnect 25,000 kilometres of Europe's rivers by 2030, but achieving this will require a paradigm shift in river restoration that recognizes the widespread impacts caused by small barriers.

Combining Nanopore direct RNA sequencing with genetics and mass spectrometry for analysis of T-loop base modifications across 42 yeast tRNA isoacceptors.

Transfer RNAs (tRNAs) contain dozens of chemical modifications. These modifications are critical for maintaining tRNA tertiary structure and optimizing protein synthesis. Here we advance the use of Nanopore direct RNA-sequencing (DRS) to investigate the synergy between modifications that are known to stabilize tRNA structure. We sequenced the 42 cytosolic tRNA isoacceptors from wild-type yeast and five tRNA-modifying enzyme knockout mutants. These data permitted comprehensive analysis of three neighboring and conserved modifications in T-loops: 5-methyluridine (m5U54), pseudouridine (Ψ55), and 1-methyladenosine (m1A58). Our results were validated using direct measurements of chemical modifications by mass spectrometry. We observed concerted T-loop modification circuits-the potent influence of Ψ55 for subsequent m1A58 modification on more tRNA isoacceptors than previously observed. Growing cells under nutrient depleted conditions also revealed a novel condition-specific increase in m1A58 modification on some tRNAs. A global and isoacceptor-specific classification strategy was developed to predict the status of T-loop modifications from a user-input tRNA DRS dataset, applicable to other conditions and tRNAs in other organisms. These advancements demonstrate how orthogonal technologies combined with genetics enable precise detection of modification landscapes of individual, full-length tRNAs, at transcriptome-scale.

Direct sequencing of total Saccharomyces cerevisiae tRNAs by LC-MS/MS.

Among RNAs, transfer RNAs (tRNAs) contain the widest variety of abundant posttranscriptional chemical modifications. These modifications are crucial for tRNAs to participate in protein synthesis, promoting proper tRNA structure and aminoacylation, facilitating anticodon:codon recognition, and ensuring the reading frame maintenance of the ribosome. While tRNA modifications were long thought to be stoichiometric, it is becoming increasingly apparent that these modifications can change dynamically in response to the cellular environment. The ability to broadly characterize the fluctuating tRNA modification landscape will be essential for establishing the molecular level contributions of individual sites of tRNA modification. The locations of modifications within individual tRNA sequences can be mapped using liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS). In this approach, a single tRNA species is purified, treated with ribonucleases, and the resulting single-stranded RNA products are subject to LC-MS/MS analysis. The application of LC-MS/MS to study tRNAs is limited by the necessity of analyzing one tRNA at a time, because the digestion of total tRNA mixtures by commercially available ribonucleases produces many short digestion products unable to be uniquely mapped back to a single site within a tRNA. We overcame these limitations by taking advantage of the highly structured nature of tRNAs to prevent the full digestion by single-stranded RNA-specific ribonucleases. Folding total tRNA prior to digestion allowed us to sequence Saccharomyces cerevisiae tRNAs with up to 97% sequence coverage for individual tRNA species by LC-MS/MS. This method presents a robust avenue for directly detecting the distribution of modifications in total tRNAs.

Plasticity, symbionts and niche construction interact in shaping dung beetle development and evolution.

Developmental plasticity is an important product of evolutionary processes, allowing organisms to maintain high fitness in the face of environmental perturbations. Once evolved, plasticity also has the potential to influence subsequent evolutionary outcomes, for example, by shaping phenotypic variation visible to selection and facilitating the emergence of novel trait variants. Furthermore, organisms may not just respond to environmental conditions through plasticity but may also actively modify the abiotic and (sym)biotic environments to which they themselves respond, causing plasticity to interact in complex ways with niche construction. Here, we explore developmental mechanisms and evolutionary consequences of plasticity in horned dung beetles. First, we discuss how post-invasion evolution of plasticity in an introduced Onthophagus species facilitated rapid range expansion and concurrent local adaptation of life history and morphology to novel climatic conditions. Second, we discuss how, in addition to plastically responding to variation in nutritional conditions, dung beetles engage in behaviors that modify the environment that they themselves respond to during later development. We document that these environment-modifying behaviors mask heritable variation for life history traits within populations, thereby shielding genetic variants from selection. Such cryptic genetic variation may be released and become selectable when these behaviors are compromised. Together, this work documents the complex interactions between plasticity, symbionts and niche construction, and highlights the usefulness of an integrative Eco-Evo-Devo framework to study the varied mechanisms and consequences of plasticity in development and evolution.

A First-in-Human Trial of a New Aqueous Ionic Liquid Embolic Material in Distal Embolization Applications.

PURPOSE: A prospective, single-arm, open-label, multicenter, first-in-human, early feasibility study was completed to evaluate the safety and performance of the GPX Embolic Device (Fluidx, Salt Lake City, Utah), a novel liquid embolic agent, for use in the peripheral vasculature when deep distal embolization is desired. MATERIALS AND METHODS: The early feasibility study evaluated the use of the device in the peripheral vasculature. Enrollment consisted of 17 patients with diverse embolization needs requiring deep distal vessel/vessel bed occlusion. Technical success, freedom from adverse events (AEs), and handling/performance characteristics were assessed with follow-up at 30 days. RESULTS: The trial enrolled 17 patients requiring distal vascular penetration of the embolic agent, including 7 with renal angiomyolipomas, 4 with renal cell carcinomas (primary and secondary), 4 with portal veins needing embolization, 1 with pelvic sarcoma, and 1 with polycystic kidney. In all cases (100%), technical success was achieved with target regions fully occluded on the first angiogram (taken immediately after delivery). Furthermore, the material received high usability ratings, as measured by a postprocedural investigator questionnaire. Most patients (15/17, 88.2%) were free from device-related severe AEs, and there were no unanticipated AEs during the study. Each patient completed a 30-day follow-up evaluation, and sites remained fully occluded in each case where imaging was available (6 [35.3%] of 17 patients had follow-up imaging where all sites were deemed occluded [100%] with a mean of 30.2 days after the procedure). CONCLUSIONS: The results of this first-in-human, early feasibility study demonstrate that the GPX Embolic Device may provide safe and effective embolization for arterial or venous applications where deep distal penetration is desired.

Ethical argument for establishing good manufacturing practice for phage therapy in the UK.

Antimicrobial resistance (AMR) poses an increasing threat to patient care and population health and there is a growing need for novel therapies to tackle AMR. Bacteriophage (phage) therapy is a re-emerging antimicrobial strategy with the potential to transform how bacterial infections are treated in patients and populations. Currently, in the UK, phages can be used as unlicensed medicinal products on a 'named-patient' basis. We make an ethical case for why it is crucially important for the UK to invest in Good Manufacturing Practice (GMP) for both ongoing unlicensed and future licensed phage therapy. Access to phages produced to GMP (GMP phages) will ensure effective patient care and better outcomes as well as health systems benefits. The UK also has the potential to become a global leader in the timely and cost-efficient manufacturing and supply of a therapy that meets internationally recognised standards.

Nuclease P1 Digestion for Bottom-Up RNA Sequencing of Modified siRNA Therapeutics.

siRNA therapeutics provide a selective and powerful approach to reduce the expression of disease-causing genes. For regulatory approval, these modalities require sequence confirmation which is typically achieved by intact tandem mass spectrometry sequencing. However, this process produces highly complex spectra which are difficult to interpret and typically results in less than full sequence coverage. We sought to develop a bottom-up siRNA sequencing platform to ease sequencing data analysis and provide full sequence coverage. Analogous to bottom-up proteomics, this process requires chemical or enzymatic digestion to reduce the oligonucleotide length down to analyzable lengths, but siRNAs commonly contain modifications that inhibit the degradation process. We tested six digestion schemes for their feasibility to digest the 2' modified siRNAs and identified that nuclease P1 provides an effective digestion workflow. Using a partial digestion, nuclease P1 provides high 5' and 3' end sequence coverage with multiple overlapping digestion products. Additionally, this enzyme provides high-quality and highly reproducible RNA sequencing no matter the RNA phosphorothioate content, 2'-fluorination status, sequence, or length. Overall, we developed a robust enzymatic digestion scheme for bottom-up siRNA sequencing using nuclease P1, which can be implemented into existing sequence confirmation workflows.

Dynamic expression of Schlafen 11 (SLFN11) in circulating tumour cells as a liquid biomarker in small cell lung cancer.

INTRODUCTION: Small cell lung cancer (SCLC) is an aggressive malignancy with no established biomarkers. Schlafen 11(SLFN11), a DNA/RNA helicase that sensitises cancer cells to DNA-damaging agents, has emerged as a promising predictive biomarker for several drug classes including platinum and PARP inhibitors. Detection of SLFN11 in circulating tumour cells (CTCs) may provide a valuable alternative to tissue sampling. METHODS: SLFN11 expression was evaluated in tumour samples and characterised in circulating tumour cells (CTC) longitudinally to determine its potential role as a biomarker of response. RESULTS: Among 196 SCLC tumours, 51% expressed SLFN11 by IHC. In addition, 20/29 extra-thoracic high-grade neuroendocrine tumours expressed SLFN11 expression. In 64 blood samples from 42 SCLC patients, 83% (53/64) of samples had detectable CTCs, and SLFN11-positive CTCs were detected in 55% (29/53). Patients actively receiving platinum treatment had the lowest number of CTCs and a lower percentage of SLFN11-positive CTCs (p = 0.014). Analysis from patients with longitudinal samples suggest a decrease in CTC number and in SLFN11 expression that correlates with clinical response. CONCLUSIONS: SLFN11 levels can be monitored in CTCs from SCLC patients using non-invasive liquid biopsies. The ability to detect SLFN11 in CTCs from SCLC patients adds a valuable tool for the detection and longitudinal monitoring of this promising biomarker.

Changes in sea ice and range expansion of sperm whales in the eclipse sound region of Baffin Bay, Canada.

Sperm whales (Physeter macrocephalus) are a cosmopolitan species but are only found in ice-free regions of the ocean. It is unknown how their distribution might change in regions undergoing rapid loss of sea ice and ocean warming like Baffin Bay in the eastern Canadian Arctic. In 2014 and 2018, sperm whales were sighted near Eclipse Sound, Baffin Bay: the first recorded uses of this region by sperm whales. In this study, we investigate the spatiotemporal distribution of sperm whales near Eclipse Sound using visual and acoustic data. We combine several published open-source, data sets to create a map of historical sperm whale presence in the region. We use passive acoustic data from two recording sites between 2015 and 2019 to investigate more recent presence in the region. We also analyze regional trends in sea ice concentration (SIC) dating back to 1901 and relate acoustic presence of sperm whales to the mean SIC near the recording sites. We found no records of sperm whale sightings near Eclipse Sound outside of the 2014/2018 observations. Our acoustic data told a different story, with sperm whales recorded yearly from 2015 to 2019 with presence in the late summer and fall months. Sperm whale acoustic presence increased over the 5-year study duration and was closely related to the minimum SIC each year. Sperm whales, like other cetaceans, are ecosystem sentinels, or indicators of ecosystem change. Increasing number of days with sperm whale presence in the Eclipse Sound region could indicate range expansion of sperm whales as a result of changes in sea ice. Monitoring climate change-induced range expansion in this region is important to understand how increasing presence of a top-predator might impact the Arctic food web.

Phase variation of a signal transduction system controls Clostridioides difficile colony morphology, motility, and virulence.

Recent work has revealed that Clostridioides difficile, a major cause of nosocomial diarrheal disease, exhibits phenotypic heterogeneity within a clonal population as a result of phase variation. Many C. difficile strains representing multiple ribotypes develop two colony morphotypes, termed rough and smooth, but the biological implications of this phenomenon have not been explored. Here, we examine the molecular basis and physiological relevance of the distinct colony morphotypes produced by this bacterium. We show that C. difficile reversibly differentiates into rough and smooth colony morphologies and that bacteria derived from the isolates display discrete motility behaviors. We identified an atypical phase-variable signal transduction system consisting of a histidine kinase and two response regulators, named herein colony morphology regulators RST (CmrRST), which mediates the switch in colony morphology and motility behaviors. The CmrRST-regulated surface motility is independent of flagella and type IV pili, suggesting a novel mechanism of cell migration in C. difficile. Microscopic analysis of cell and colony structure indicates that CmrRST promotes the formation of elongated bacteria arranged in bundled chains, which may contribute to bacterial migration on surfaces. In a hamster model of acute C. difficile disease, the CmrRST system is required for disease development. Furthermore, we provide evidence that CmrRST phase varies during infection, suggesting that the intestinal environment impacts the proportion of CmrRST-expressing C. difficile. Our findings indicate that C. difficile employs phase variation of the CmrRST signal transduction system to generate phenotypic heterogeneity during infection, with concomitant effects on bacterial physiology and pathogenesis.

Pseudouridinylation of mRNA coding sequences alters translation.

Chemical modifications of RNAs have long been established as key modulators of nonprotein-coding RNA structure and function in cells. There is a growing appreciation that messenger RNA (mRNA) sequences responsible for directing protein synthesis can also be posttranscriptionally modified. The enzymatic incorporation of mRNA modifications has many potential outcomes, including changing mRNA stability, protein recruitment, and translation. We tested how one of the most common modifications present in mRNA coding regions, pseudouridine (Ψ), impacts protein synthesis using a fully reconstituted bacterial translation system and human cells. Our work reveals that replacing a single uridine nucleotide with Ψ in an mRNA codon impedes amino acid addition and EF-Tu GTPase activation. A crystal structure of the Thermus thermophilus 70S ribosome with a tRNAPhe bound to a ΨUU codon in the A site supports these findings. We also find that the presence of Ψ can promote the low-level synthesis of multiple peptide products from a single mRNA sequence in the reconstituted translation system as well as human cells, and increases the rate of near-cognate Val-tRNAVal reacting on a ΨUU codon. The vast majority of Ψ moieties in mRNAs are found in coding regions, and our study suggests that one consequence of the ribosome encountering Ψ can be to modestly alter both translation speed and mRNA decoding.

Designing a small-sided game to elicit attacking tactical behaviour in professional rugby union forwards.

This study aimed to investigate the consistency of attacking tactical and technical behaviour, and physical characteristics, over multiple bouts, and variability across days, of a specific rugby union forwards small-sided game (SSG). Data was collected from 21 professional rugby union forwards during four training sessions. The SSG, consisting of five bouts of work (150-s) interspersed by passive recovery (75-s), aimed to elicit specific attacking tactical behaviour. Tactical behaviour (i.e., regularity of attacking shape [entropy]), and technical (e.g., passes) and physical (e.g., total distance) characteristics were quantified. Results showed that technical characteristics remained consistent, whereas the regularity of width of the attacking shape and two physical characteristics (i.e., total distance, training impulse) varied across bouts. However, these effects had limited practical significance. Technical characteristics were consistent across days, but minimal variability was observed for tactical behaviour and physical characteristics, as shown by their small random effects with 95% profile likelihood confidence intervals (PLCI) including zero (e.g., SD[95%PLCI] = 0.03[0.00, 0.06]). Consequently, consistency of stimulus over bouts and days is achievable for the majority of the variables investigated, thus supporting the use of SSG to elicit consistent attacking behaviour, but also technical and physical characteristics in rugby union forwards.

Can Team-Sport Athletes Accurately Run at Submaximal Sprinting Speeds? Implications for Rehabilitation and Warm-Up Protocols.

ABSTRACT: Darrall-Jones, J, Roe, G, Cremen, E, and Jones, B. Can team-sport athletes accurately run at submaximal sprinting speeds? Implications for rehabilitation and warm-up protocols. J Strength Cond Res 36(8): 2218-2222, 2022-The aim of this study is to examine the ability of team-sport athletes to accurately run at a range of submaximal sprint velocities (60-90% maximal velocity; Vmax) under verbal instruction without any objective feedback. Twelve professional male rugby union players (age 19.7 ± 0.9 years, body mass 98.3 ± 13.9 kg, height 184.0 ± 7.5 cm) were verbally instructed to complete three 40-m sprints at each of 60, 70, 80, and 90% of Vmax in a randomized order. Percentage Vmax achieved during each sprint was compared with criterion velocities calculated from Vmax testing undertaken a week prior. Players underestimated (ran faster) their sprint velocity when asked to run at 60% (very large to extremely large mean bias, 23%; range, 57-88% Vmax), 70% (large to very large, 11%; 67-93% Vmax), and 80% (small, 2%; 71-91% Vmax) of their Vmax, whereas overestimated (ran slower) their sprint velocity when asked to run at 90% Vmax (moderate, -4%; 77-95% Vmax). Team sport players may require objective feedback when performing submaximal sprinting to ensure that velocities achieved are similar to those prescribed. This may be particularly important where graded exposure to maximum velocities is required, for example during rehabilitation or warm-ups.

Risk of Fractures in Stroke Patients Treated With a Selective Serotonin Reuptake Inhibitor: A Systematic Review and Meta-Analysis.

Background and Purpose: Stroke survivors have an increased risk of depression and bone fractures. Selective serotonin reuptake inhibitors (SSRIs) have been associated with an increased risk of fractures in observational studies. Several randomized controlled trials (RCTs) reporting the effect of SSRIs on the risk of fractures in stroke survivors have been published recently but have not been subject to a meta-analysis. We aimed to determine the risk of fractures associated with the use of SSRIs, and the risk of falls, seizures, and recurrent strokes as possible mediators of fractures, in stroke survivors. Methods: We conducted a systematic review and meta-analysis of RCTs of SSRIs in stroke survivors according to a protocol registered in PROSPERO (CRD42020192632). Web of Science, EMBASE, PsycINFO, and Ovid Medline/PubMed bibliographic databases, clinical trial registers, and grey literature sources were searched. RCTs of SSRIs versus placebo or no intervention that report the risk of fractures in adult survivors of hemorrhagic or ischemic stroke were included. Two reviewers independently screened search results and extracted data. Meta-analyses were conducted for each outcome using the Mantel-Haenszel random-effects models. Results: The searches yielded 683 records, of which 4 RCTs of 6 months duration with a total of 6549 participants were included in the meta-analysis: 3 studies of fluoxetine and 1 study of citalopram. Treatment with an SSRI for 6 months increased the risk of fractures with a risk ratio of 2.36 (95% CI, 1.64­3.39) compared with placebo. The risk of falls, seizures, and recurrent stroke was not statistically significantly increased. Only studies of fluoxetine and citalopram were available for inclusion in the review, and hence the generalizability of the findings to other SSRIs is uncertain. Conclusions: Based on available RCTs of fluoxetine and citalopram, SSRIs used for 6 months doubled the risk of fractures in stroke survivors. Registration: https://www.crd.york.ac.uk/prospero/; Unique identifier: CRD42020192632.

NCCN Guidelines® Insights: Palliative Care, Version 2.2021.

Palliative care has evolved to be an integral part of comprehensive cancer care with the goal of early intervention to improve quality of life and patient outcomes. The NCCN Guidelines for Palliative Care provide recommendations to help the primary oncology team promote the best quality of life possible throughout the illness trajectory for each patient with cancer. The NCCN Palliative Care Panel meets annually to evaluate and update recommendations based on panel members' clinical expertise and emerging scientific data. These NCCN Guidelines Insights summarize the panel's recent discussions and highlights updates on the importance of fostering adaptive coping strategies for patients and families, and on the role of pharmacologic and nonpharmacologic interventions to optimize symptom management.

Palliative radiotherapy at the end of life: a critical review.

When delivered with palliative intent, radiotherapy can help to alleviate a multitude of symptoms related to advanced cancer. In general, time to symptom relief is measured in weeks to months after the completion of radiotherapy. Over the past several years, an increasing number of studies have explored rates of radiotherapy use in the final months of life and have found variable rates of radiotherapy use. The optimal rate is unclear, but would incorporate anticipated efficacy in patients whose survival allows it and minimize overuse among patients with expected short survival. Clinician prediction has been shown to overestimate the length of survival in repeated studies. Prognostic indices can provide assistance with estimations of survival length and may help to guide treatment decisions regarding palliative radiotherapy in patients with potentially short survival times. This review explores the recent studies of radiotherapy near the end of life, examines general prognostic models for patients with advanced cancer, describes specific clinical circumstances when radiotherapy may and may not be beneficial, and addresses open questions for future research to help clarify when palliative radiotherapy may be effective near the end of life.

The microbiology of diabetic foot infections: a meta-analysis.

BACKGROUND: Diabetic foot ulcers are a common complication of poorly controlled diabetes and often become infected, termed diabetic foot infection. There have been numerous studies of the microbiology of diabetic foot infection but no meta-analysis has provided a global overview of these data. This meta-analysis aimed to investigate the prevalence of bacteria isolated from diabetic foot infections using studies of any design which reported diabetic foot infection culture results. METHODS: The Medline, EMBASE, Web of Science and BIOSIS electronic databases were searched for studies published up to 2019 which contained microbiological culture results from at least 10 diabetic foot infection patients. Two authors independently assessed study eligibility and extracted the data. The main outcome was the prevalence of each bacterial genera or species. RESULTS: A total of 112 studies were included, representing 16,159 patients from which 22,198 microbial isolates were obtained. The organism most commonly identified was Staphylococcus aureus, of which 18.0% (95% CI 13.8-22.6%; I2 = 93.8% [93.0-94.5%]) was MRSA. Other highly prevalent organisms were Pseudomonas spp., E. coli and Enterococcus spp. A correlation was identified between Gross National Income and the prevalence of Gram positive or negative organisms in diabetic foot infections. CONCLUSION: The microbiology of diabetic foot infections is diverse, but S. aureus predominates. The correlation between the prevalence of Gram positive and negative organisms and Gross National Income could reflect differences in healthcare provision and sanitation. This meta-analysis has synthesised multiple datasets to provide a global overview of the microbiology of diabetic foot infections that will help direct the development of novel therapeutics.

A systematic review of small sided games within rugby: Acute and chronic effects of constraints manipulation.

Small-sided games is a commonly used training method to develop technical, tactical and physical qualities concurrently. However, a review of small-sided games in rugby football codes (e.g. rugby union, rugby league) is not available. This systematic review aims to investigate the acute responses and chronic adaptations of small-sided games within rugby football codes considering the constraints applied. Four electronical databases were systematically searched until August 2020. Acute and chronic studies investigating rugby football codes small-sided games, with healthy amateur and professional athletes were included. Twenty studies were eventually included: 4 acute and 1 chronic in rugby union, 13 acute and 2 chronic in rugby league. Acute studies investigated task and individual constraints. Chronic studies showed that small-sided games would be an effective training method to improve physical performance. Current research in rugby football codes is heavily biased towards investigating how manipulating constraints can affect the physical characteristics of small-sided games, with limited literature investigating the effect on technical skills, and no studies investigating tactical behaviour. Future research is needed to evidence the effects of constraint manipulation on technical and tactical behaviour of rugby football players in small-sided games, in addition to physical characteristics.