Genomic Regions Associated with Resistance to Three Rusts in CIMMYT Wheat Line "Mokue#1"

Understanding the genetic basis of rust resistance in elite CIMMYT wheat germplasm enhances breeding and deployment of durable resistance globally. "Mokue#1", released in 2023 in Pakistan as TARNAB Gandum-1, has exhibited high levels of resistance to stripe rust, leaf rust, and stem rust pathotypes present at multiple environments in Mexico and Kenya at different times. To determine the genetic basis of resistance, a F5 recombinant inbred line (RIL) mapping population consisting of 261 lines was developed and phenotyped for multiple years at field sites in Mexico and Kenya under the conditions of artificially created rust epidemics. DArTSeq genotyping was performed, and a linkage map was constructed using 7892 informative polymorphic markers. Composite interval mapping identified three significant and consistent loci contributed by Mokue: QLrYr.cim-1BL and QLrYr.cim-2AS on chromosome 1BL and 2AS, respectively associated with stripe rust and leaf rust resistance, and QLrSr.cim-2DS on chromosome 2DS for leaf rust and stem rust resistance. The QTL on 1BL was confirmed to be the Lr46/Yr29 locus, whereas the QTL on 2AS represented the Yr17/Lr37 region on the 2NS/2AS translocation. The QTL on 2DS was a unique locus conferring leaf rust resistance in Mexico and stem rust resistance in Kenya. In addition to these pleiotropic loci, four minor QTLs were also identified on chromosomes 2DL and 6BS associated with stripe rust, and 3AL and 6AS for stem rust, respectively, using the Kenya disease severity data. Significant decreases in disease severities were also demonstrated due to additive effects of QTLs when present in combinations.

Experimental Evidence for the Spiral Spin Liquid in LiYbO_{2}

Spiral spin liquids are an exotic class of correlated paramagnets with an enigmatic magnetic ground state composed of a degenerate manifold of fluctuating spin spirals. Experimental realizations of the spiral spin liquid are scarce, mainly due to the prominence of structural distortions in candidate materials that can trigger order-by-disorder transitions to more conventionally ordered magnetic ground states. Expanding the pool of candidate materials that may host a spiral spin liquid is therefore crucial to realizing this novel magnetic ground state and understanding its robustness against perturbations that arise in real materials. Here, we show that the material LiYbO_{2} is the first experimental realization of a spiral spin liquid predicted to emerge from the J_{1}-J_{2} Heisenberg model on an elongated diamond lattice. Through a complementary combination of high-resolution and diffuse neutron magnetic scattering studies on a polycrystalline sample, we demonstrate that LiYbO_{2} fulfills the requirements for the experimental realization of the spiral spin liquid and reconstruct single-crystal diffuse neutron magnetic scattering maps that reveal continuous spiral spin contours-a characteristic experimental hallmark of this exotic magnetic phase.

Relocation of Sr48 to Chromosome 2D Using an Alternative Mapping Population and Development of a Closely Linked Marker Using Diverse Molecular Technologies

The Ug99-effective stem rust resistance gene Sr48 was mapped to chromosome 2A based on its repulsion linkage with Yr1 in an Arina/Forno recombinant inbred line (RIL) population. Attempts to identify markers closely linked to Sr48 using available genomic resources were futile. This study used an Arina/Cezanne F_5:7 RIL population to identify markers closely linked with Sr48. Using the Arina/Cezanne DArTseq map, Sr48 was mapped on the short arm of chromosome 2D and it co-segregated with 12 markers. These DArTseq marker sequences were used for BlastN search to identify corresponding wheat chromosome survey sequence (CSS) contigs, and PCR-based markers were developed. Two simple sequence repeat (SSR) markers, sun590 and sun592, and two Kompetitive Allele-Specific PCR (KASP) markers were derived from the contig 2DS_5324961 that mapped distal to Sr48. Molecular cytogenetic analysis using sequential fluorescent in situ hybridization (FISH) and genomic in situ hybridization (GISH) identified a terminal translocation of chromosome 2A in chromosome 2DL of Forno. This translocation would have led to the formation of a quadrivalent involving chromosomes 2A and 2D in the Arina/Forno population, which would have exhibited pseudo-linkage between Sr48 and Yr1 in chromosome 2AL. Polymorphism of the closet marker sunKASP_239 among a set of 178 wheat genotypes suggested that this marker can be used for marker-assisted selection of Sr48.

Genotyping by Sequencing Advancements in Barley

Barley is considered an ideal crop to study cereal genetics due to its close relationship with wheat and diploid ancestral genome. It plays a crucial role in reducing risks to global food security posed by climate change. Genetic variations in the traits of interest in crops are vital for their improvement. DNA markers have been widely used to estimate these variations in populations. With the advancements in next-generation sequencing, breeders could access different types of genetic variations within different lines, with single-nucleotide polymorphisms (SNPs) being the most common type. However, genotyping barley with whole genome sequencing (WGS) is challenged by the higher cost and computational demand caused by the large genome size (5.5GB) and a high proportion of repetitive sequences (80%). Genotyping-by-sequencing (GBS) protocols based on restriction enzymes and target enrichment allow a cost-effective SNP discovery by reducing the genome complexity. In general, GBS has opened up new horizons for plant breeding and genetics. Though considered a reliable alternative to WGS, GBS also presents various computational difficulties, but GBS-specific pipelines are designed to overcome these challenges. Moreover, a robust design for GBS can facilitate the imputation to the WGS level of crops with high linkage disequilibrium. The complete exploitation of GBS advancements will pave the way to a better understanding of crop genetics and offer opportunities for the successful improvement of barley and its close relatives.

Ethnic disparities in mortality among overweight or obese adults with newly diagnosed type 2 diabetes: a population-based cohort study

PURPOSE

Ethnic variation in risk of type 2 diabetes is well established, but its impact on mortality is less well understood. This study investigated the risk of all-cause and cardiovascular mortality associated with newly diagnosed type 2 diabetes in White, Asian and Black adults who were overweight or obese.

METHODS

This population-based cohort study used primary care records from the UK Clinical Practice Research Datalink, linked with secondary care and death registry records. A total of 193,528 obese or overweight adults (BMI of 25 or greater), with ethnicity records and no pre-existing type 2 diabetes were identified between 01 January 1995 and 20 April 2018. Multivariable Cox proportional hazards regression estimated hazards ratios (HR) for incident type 2 diabetes in different ethnic groups. Adjusted hazards ratios for all-cause and cardiovascular mortality were determined in individuals with newly diagnosed type 2 diabetes.

RESULTS

During follow-up (median 9.8 years), the overall incidence rate of type 2 diabetes (per 1,000 person-years) was 20.10 (95% CI 19.90-20.30). Compared to Whites, type 2 diabetes risk was 2.2-fold higher in Asians (HR 2.19 (2.07-2.32)) and 30% higher in Blacks (HR 1.34 (1.23-1.46)). In individuals with newly diagnosed type 2 diabetes, the rates (per 1,000 person-years) of all-cause mortality and cardiovascular mortality were 24.34 (23.73-24.92) and 4.78 (4.51-5.06), respectively. Adjusted hazards ratios for mortality were significantly lower in Asians (HR 0.70 (0.55-0.90)) and Blacks (HR 0.71 (0.51-0.98)) compared to Whites, and these differences in mortality risk were not explained by differences in severity of hyperglycaemia.

CONCLUSIONS/INTERPRETATION

Type 2 diabetes risk in overweight and obese adults is greater in Asian and Black compared to White ethnic populations, but mortality is significantly higher in the latter. Greater attention to optimising screening, disease and risk management appropriate to all communities with type 2 diabetes is needed.

Influence of water on the microscopic dynamics of 1-butyl-3-methylimidazolium tetrafluoroborate studied by means of quasielastic neutron scattering

We present a systematic study on the effect of water on the microscopic dynamics of 1-butyl-3-methylimidazolium tetrafluoroborate by means of quasielastic neutron scattering. By mixing the ionic liquid with either heavy or light water, the different contributions to the quasielastic broadening could be identified and treated separately. This study was performed at room temperature, which is more than 15 °C above the demixing line. Our results show that even small amounts of water accelerate the diffusion mechanisms considerably. While samples with small water percentage reveal a diffusion process confined within ionic liquid nanodomains, an admixture of more than 15 wt. % water relieves the confinement. Furthermore, the presence of two water species was identified: one behaving as free water, whereas the other was interpreted as a component bound to the ionic liquid motion. Based on the fact that water preferentially binds to the BF4 anion, which itself has a negligible contribution to the scattered intensity, our experiments reveal unprecedented information about the microscopic anion dynamics.

Septal late gadolinium enhancement on Cardiac MRI predicts failure to achieve left bundle pacing

Funding Acknowledgements

Type of funding sources: Foundation. Main funding source(s): British Heart Foundation

Background; Left bundle area pacing is a novel technique that provides direct stimulation of cardiac conduction tissue in order to deliver physiological ventricular activation. The approach for left bundle area pacing is transseptal lead implantation, where the lead is advanced from the right ventricular side of the septum to the left ventricular side to capture the proximal left bundle. Observational data suggests that whilst this is a safe and feasible method, implant success rate is not 100%, and appears to be lower in patients with a cardiac resynchronization therapy (CRT) indication rather than a bradycardia indication for pacing. The mechanisms for failure to advance the lead through the ventricular septum are not well understood.

Purpose; We used pre-procedural CMR to determine whether there are features which can help identify patients where lead implantation may be challenging.  We assessed whether the extent and location of septal late gadolinium enhancement identified patients in whom left bundle area pacing will be challenging.  We hypothesized that the presence of extensive scar in the septum impedes advancing the lead to the left ventricular septum and prevents capture of the left bundle.

Methods; Patients underwent cardiac MRI including motion corrected free-breathing late gadolinium enhancement imaging1 before implantation.  Scar was quantified using the full height half maximum method and expressed as the overall proportion of myocardial mass in the basal anteroseptal and basal inferoseptal segments, as shown in Figure 1.  Left bundle area pacing was then attempted in patients with a CRT indication for pacing.  We compared the extent of septal scar between patients in whom left bundle area pacing was achieved and those where there was failure to advance the lead deep into the septum.

Results; 12 patients (11 male, 1 female), with average age 72 (IQR 63 to 78) and LVEF 30% (IQR 26 to 33) were studied.  There was failure to advance the lead deep into the septum in 4 patients.  There was a significantly higher basal septal scar burden in those patients where there was failure to advance the left bundle lead compared to those in which left bundle capture was achieved as shown in Figure 2 (median 55% and 5% respectively, p-value 0.02 by Wilcoxon signed rank test).

Conclusion; The presence and extent of late gadolinium enhancement in the basal septum appears to be an important determinant of successful implantation of left bundle pacing lead using current implant technology. This may be because extensive septal scar prevents advancement of the pacing lead through the septum. Cardiac MRI before left bundle area pacing is likely to be useful in procedural planning.

An adult plant stripe rust resistance gene maps on chromosome 7A of Australian wheat cultivar Axe

An adult plant stripe rust resistance gene Yr75 was located on the long arm of chromosome 7A. Fine mapping of the region identified markers closely linked with Yr75. Australian wheat cultivar Axe produced resistant to moderately resistant stripe rust responses under field conditions and was exhibiting seedling responses varying from 33C to 3+ under greenhouse conditions. Experiments covering tests at different growth stages (2nd, 3rd and 4th leaf stages) demonstrated the clear expression of resistance at the 4th leaf stage under controlled-environment greenhouse conditions. A recombinant inbred line (RIL) population was developed from the Axe/Nyabing-3 (Nyb) cross. Genetic analysis of Axe/Nyb RIL population in the greenhouse at the 4th leaf stage showed monogenic inheritance of stripe rust resistance. Selective genotyping using the iSelect 90 K Infinium SNP genotyping array was performed, and the resistance locus was mapped to the long arm of chromosome 7A and named Yr75. The Axe/Nyb RIL population was genotyped using a targeted genotype-by-sequencing assay, and the resistance-linked SNPs were converted into kompetitive allele-specific PCR (KASP) markers. These markers were tested on the entire Axe/Nyb RIL population, and markers sunKASP_430 and sunKASP_427 showed close association with Yr75 in the Axe/Nyb RIL population. A high-resolution mapping family of 1032 F₂ plants from the Axe/Nyb cross was developed and genotyped with sunKASP_430 and sunKASP_427, and these markers flanked Yr75 at 0.3 cM and 0.4 cM, respectively. These markers cover 1.24 Mb of the physical map of Chinese Spring, and this information will be useful for map-based cloning of Yr75.

Non-selective and selective His bundle pacing both preserve left ventricular activation time and pattern

Funding Acknowledgements

Type of funding sources: Public Institution(s). Main funding source(s): British Heart Foundation

Background: His bundle pacing can be achieved in two ways

selective His bundle pacing, where the His bundle is captured alone, and non-selective His bundle pacing, where local myocardium is also captured resulting a pre-excited ECG appearance. We assessed the impact of this ventricular pre-excitation on left and right ventricular dys-synchrony.

Methods

We recruited patients who displayed both selective and non-selective His bundle pacing. We performed non-invasive epicardial electrical mapping to determine left and right ventricular activation times and patterns.

Results

In the primary analysis (n = 20, all patients), non-selective His bundle pacing did not prolong LVAT compared to select His bundle pacing by a pre-specified non-inferiority margin of 10ms (LVAT prolongation: -5.5ms, 95% confidence interval (CI): -0.6 to -10.4, non-inferiority p < 0.0001). Non-selective His bundle pacing did not prolong right ventricular activation time (4.3ms, 95%CI: -4.0 to 12.8, p = 0.296) but did prolong QRS duration (22.1ms, 95%CI: 11.8 to 32.4, p = 0.0003).

In patients with narrow intrinsic QRS (n = 6), non-selective His bundle pacing preserved left ventricular activation time (-2.9ms, 95%CI: -9.7 to 4.0, p = 0.331) but prolonged QRS duration (31.4ms, 95%CI: 22.0 to 40.7, p = 0.0003) and mean right ventricular activation time (16.8ms, 95%CI: -5.3 to 38.9, p = 0.108) compared to selective His bundle pacing.

Activation pattern of the left ventricular surface was unchanged between selective and non-selective His bundle pacing. Non-selective His bundle pacing produced early basal right ventricular activation, which was not observed with selective His bundle pacing.

Conclusions

Compared to selective His bundle pacing, local myocardial capture during non-selective His bundle pacing produces right ventricular pre-excitation resulting in prolongation of QRS duration. However, non-selective His bundle pacing preserves the left ventricular activation time and pattern of selective His bundle pacing. When choosing between selective and non-selective His bundle pacing, left ventricular dyssynchrony is not an important factor. Abstract Figure: Selective vs Non-Selective HBP

Lr80: A new and widely effective source of leaf rust resistance of wheat for enhancing diversity of resistance among modern cultivars

A new leaf rust resistance gene Lr80 was identified and closely linked markers were developed for its successful pyramiding with other marker-tagged genes to achieve durable control of leaf rust. Common wheat landrace Hango-2, collected in 2006 from the Himalayan area of Hango, District Kinnaur, in Himachal Pradesh, exhibited a very low infection type (IT;) at the seedling stage to all Indian Puccinia triticina (Pt) pathotypes, except the pathotype 5R9-7 which produced IT 3⁺. Genetic analysis based on Agra Local/Hango-2-derived F₃ families indicated monogenic control of leaf rust resistance, and the underlying locus was temporarily named LrH2. Bulked segregant analysis using 303 simple sequence repeat (SSR) markers located LrH2 in the short arm of chromosome 2D. An additional set of 10 chromosome 2DS-specific markers showed polymorphism between the parents and these were mapped on the entire Agra Local/Hango-2 F₃ population. LrH2 was flanked by markers cau96 (distally) and barc124 (proximally). The 90 K Infinium SNP array was used to identify SNP markers linked with LrH2. Markers KASP_17425 and KASP_17148 showed association with LrH2. Comparison of seedling leaf rust response data and marker locations across different maps demonstrated the uniqueness of LrH2 and it was formally named Lr80. The Lr80-linked markers KASP_17425, KASP_17148 and barc124 amplified alleles/products different to Hango-2 in 82 Australian cultivars indicating their robustness for marker-assisted selection of this gene in wheat breeding programs.

From One- to Two-Magnon Excitations in the S=3/2 Magnet β-CaCr_{2}O_{4}

We apply neutron spectroscopy to measure the magnetic dynamics in the S=3/2 magnet β-CaCr_{2}O_{4} (T_{N}=21  K). The low-energy fluctuations, in the ordered state, resemble large-S linear spin waves from the incommensurate ground state. However, at higher energy transfers, these semiclassical and harmonic dynamics are replaced by an energy and momentum broadened continuum of excitations. Applying kinematic constraints required for energy and momentum conservation, sum rules of neutron scattering, and comparison against exact diagonalization calculations, we show that the dynamics at high-energy transfers resemble low-S one-dimensional quantum fluctuations. β-CaCr_{2}O_{4} represents an example of a magnet at the border between classical Néel and quantum phases, displaying dual characteristics.

Colonoscopy and flexible sigmoidoscopy for follow-up of patients with left-sided diverticulitis

INTRODUCTION

The prevalence of diverticular disease has been increasing in the western world over the last few decades, causing a growing burden on health care systems. This study compared the uses of flexible sigmoidoscopy with colonoscopy as a follow-up investigation for patients diagnosed with acute left-sided diverticulitis and to evaluate the need for using either procedure.

MATERIALS AND METHODS

A retrospective study of 327 patients diagnosed with acute diverticulitis was carried out. Of this total, 240 patients with left-sided diverticulitis diagnosed via computed tomography were included. These patients were categorised into two equal groups: the first 120 patients underwent colonoscopy and the second 120 patients underwent flexible sigmoidoscopy.

RESULTS

All colonoscopes and flexible sigmoidoscopes confirmed the computed tomography diagnosis of sigmoid diverticular disease with no major new findings. All colonoscopes and flexible sigmoidoscopes were reported as having no complications, with nine colonoscopes reported as being difficult compared with only three flexible sigmoidoscopes. All biopsies were reported as no malignancy. Full bowel preparation was required in all colonoscopes, compared with no preparation required for flexible sigmoidoscopes.

CONCLUSIONS

There is no evidence to support the routine use of endoscopic evaluation after an episode of left-sided diverticulitis diagnosed on computed tomography if no worrying radiological findings have been reported. This study supports similar findings from other studies and therefore we disagree with The Royal College of Surgeons of England (Association of Coloproctology of Great Britain and Ireland recommendations) commissioning guide, which advocates routine surveillance of the colon.

P967Role of low voltage ablation in catheter ablation of patients with persistent AF- a single centre experience

Funding Acknowledgements

Research grant from Abbott

Introduction

We have recently described a novel evaluation of AF voltage which correlates better with MRI-DE defined scar than sinus rhythm voltage. We evaluated the clinical efficacy of additional voltage-based substrate modification in the Persistent AF patient cohort in a single centre case series.

Methods

22 PsAF patients undergoing catheter ablation were recruited. Left atrial electroanatomical maps were created in AF before any ablation was performed in all patients. Mean peak to peak AF voltage mapping was undertaken using 8s segments of AF (<0.35mV).  PVI was then performed in all patients after which, further ablation lesions were delivered on the underlying scar tissue (transection, box formation or homogenisation).

Results

Of the 22 patients currently under follow up, 16 patients are more than 12 months after their initial procedure. 11/16 patients have had no recurrence and no patient is currently on anti-arrhythmic medication.

Conclusion

From our series, 69% of PsAF patients remain arrhythmia free at one year follow up post blanking period with a single procedure. Ablation of low voltage areas appears to infer incremental benefit in the Persistent AF population.

Table 1 Mean Age, yrs 64 ± 9 Male 19 (86.3) Diabetes mellitus 1 (4.5) Hypertension 7 (31.8) TIA/CVA 2 (9) Left ventricular EF ≥55% 22 (100.0) LA size (diameter, according to British Society of Echocardiography Guidelines) Normal -Mild 12 (54.5) Moderate - Severe 10 (45.5) Mean AF duration, months 24.2 ± 20.8 Current antiarrhythmic strategy Amiodarone 3 (13.6) Sotalol 1 (4.5) Current anticoagulation Warfarin 3 (13.6) Direct oral anticoagulants 19 (86.3) Values are mean ± SD or N (%) or duration in months ± SD AF = atrial fibrillation; CVA= cerebrovascular accident; EF = ejection fraction; LA = left atrium; TIA = transient ischaemic attack. Baseline characteristics of patients (n = 22)

Abstract Figure. Ablation sets and AF Voltage

Whole genome sequence analysis and in vitro probiotic characteristics of a Lactobacillus strain Lactobacillus paracasei ZFM54

AIM

The aim was to identify a Lactobacillus strain with potential probiotic characteristics by whole-genome sequence analysis and in vitro experimental studies.

METHODS AND RESULTS

The whole-genome sequencing was carried out using PacBio RSII sequencing method and Illumina's paired-end sequencing technology. Gene prediction and annotation were achieved using GlimmerVersion 3.02 and NCBI prokaryotic Genome Annotation Pipeline. Identification was done by biochemical tests and 16S rRNA sequence analysis. mega 6 software was used to build phylogenetic tree. Antagonism against pathogen was determined by agar well diffusion method. Resistance and stability to bile, simulated gastric acid, different salt concentration and thermostability were investigated. Hydrophobicity assay, aggregation assay and anti-oxidation assay were performed to check further probiotic traits. Finally antibiotic susceptibility and acute oral toxicity of the strain in mice were investigated to check its safety status. The strain showed >99% similarity to Lactobacillus paracasei which was further confirmed by biochemical tests. It significantly inhibited pathogens in agar well diffusion assay. It showed tolerance to simulated gastric acid (pH 3), 0·3% bile salt and 10% NaCl. Significant hydrophobic, aggregation and anti-oxidizing activities were observed. No resistance to antibiotics tested was observed and no adverse effects during acute oral toxicity in mice were detected.

CONCLUSIONS

Lactobacillus paracasei ZFM 54, a new and safe Lactobacillus strain was identified with numerous probiotic-associated genes and characteristics confirmed by experimental studies.

SIGNIFICANCE AND IMPACT OF THE STUDY

A new probiotic strain has been identified which is highly stable, safe and suitable to be used in health and food industries.

How genomic information is accessed in clinical practice: an electronic survey of UK general practitioners

Genomic technologies are having an increasing impact across medicine, including primary care. To enable their wider adoption and realize their potential, education of primary health-care practitioners will be required. To enable the development of such resources, understanding where GPs currently access genomic information is needed. One-hundred fifty-nine UK GPs completed the survey in response to an open invitation, between September 2017 and September 2018. Questions were in response to 4 clinical genomic scenarios, with further questions exploring resources used for rare disease patients, direct-to-consumer genetic testing and collecting a family history. Respondents were most commonly GP principals (independent GPs who own their clinic) (64.8%), aged 35-49 years (54%), worked as a GP for more than 15 years (44%) and practiced within suburban locations (typically wealthier) (50.3%). The most popular 'just in time' education source for all clinical genomic scenarios were online primary care focussed resources with general Internet search engines also popular. For genomic continuous medical education, over 70% of respondents preferred online learning. Considering specific scenarios, local guidelines were a popular resource for the familial breast cancer scenario. A large proportion (41%) had not heard of Genomics England's 100,000 genome project. Few respondents (4%) would access rare disease specific Internet resources (Orphanet, OMIM). Twenty-five percent of respondents were unsure how to respond to a direct-to-consumer commercial genetic test query, with 41% forwarding such queries to local genetic services. GPs require concise, relevant, primary care focussed resources in trusted and familiar online repositories of information. Inadequate genetic education of GPs could increase burden on local genetic services.

Identification of a new source of stripe rust resistance Yr82 in wheat

Stripe rust resistance gene, Yr82, was mapped in chromosome 3BL using SNP markers. Yr82 interacted with Yr29 to produce lower stripe rust responses at the adult plant stage. Landrace Aus27969 produced low infection types against Australian Puccinia striiformis f. sp. tritici (Pst) pathotypes. A recombinant inbred line (RIL) F₇ population from the Aus27969/Avocet S cross was developed. Monogenic segregation for seedling stripe rust response was observed among the RIL population, and the resistance locus was named Yr82. Bulk segregant analysis performed using the iSelect wheat 90 K Infinium SNP array located Yr82 in the long arm of chromosome 3B. The RIL population was screened against stripe rust under field conditions and was genotyped with targeted genotyping-by-sequencing assay. QTL analysis detected the involvement of chromosomes 1B and 3B in controlling stripe rust resistance carried by Aus27969. Incorporation of Yr82 and marker SNPLr46G22 into the linkage map showed that the QTL in 1B and 3B represented Yr29 and Yr82, respectively. Kompetitive allele-specific PCR (KASP) markers sun KASP_300 and KASP_8775 flanked Yr82 distally and proximally, respectively, each at 2 cM distance. These Yr82-linked markers were polymorphic among 84% of Australian cultivars and can be used for marker-assisted selection of Yr82.

P6594Granger Causality-based analysis to accurately identify specific electrophenotypes of myocardial fibrillation

Background

Clinical identification of fibrillation drivers remains challenging in both atrial and ventricular fibrillation (VF). In this study, we developed novel tools using granger causality (GC) analysis for quantifying the causal relationship between neighbouring fibrillatory signals. We tested whether it was adaptable to low resolution, limited coverage and sequentially acquired data for quantifying global organisation of VF and mapping regions with stable rotational drivers (RDs).

Methods

Eighteen Sprague-Dawley rat hearts were perfused ex vivo for optical mapping studies. VF with differing degrees of organisation was induced with carbenoxolone (10–50μM, n=8), or prior maturation of patchy ventricular fibrosis (n=10) generated by ischaemia-reperfusion. After phase mapping, the data was downsampled to 25% of full resolution to develop validated GC-based tools. The causality pairing index (CPI), a global measure of organisation, quantified propagational effects between all neighboring signals. Low-resolution GC-vector maps localized areas harboring RDs and quantified the prevalence of RDs over time using a novel index called circular interdependence value (CIV). These GC-based tools were then adapted to analyze low-resolution multi-electrode electrograms of sixteen persistent-AF (psAF) patients presenting for a first ablation procedure.

Results

A spectrum of fibrillatory organisation and mechanisms in VF was observed. In rat VF there was a positive correlation between CPI and the number of stable RDs (R2=0.41, p=0.004), and CIV showed a significant difference in driver vs non-driver regions (0.91±0.05 vs 0.35±0.06, p=0.0002). Similarly, in psAF patients, there was a positive correlation between CPI and the number of stable RDs (R2=0.56, p≤0.001). GC vector mapping showed that 8/16 of patients had at least one RD area, and 8/16 had chaotic activity with no RDs.

Conclusion

Mechanisms of myocardial fibrillation occurs along a spectrum between organized activity with discrete areas harboring RDs and disorganised myocardial activation with no RDs. GC maps can be utilised for identifying regions localising RDs with sequential mapping in limited spatial resolution and coverage. In psAF GC-based analysis accurately identified specific fibrillatory mechanisms from low-resolution mapping. GC vector mapping holds potential for development with human fibrillation data as a mapping tool for driver guided ablation.

Acknowledgement/Funding

BHF Programme Grant PG/16/17/32069

Assessing the severity of Type 2 diabetes using clinical data-based measures: a systematic review

AIMS

To identify and critically appraise measures that use clinical data to grade the severity of Type 2 diabetes.

METHODS

We searched MEDLINE, Embase and PubMed between inception and June 2018. Studies reporting on clinical data-based diabetes-specific severity measures in adults with Type 2 diabetes were included. We excluded studies conducted solely in participants with other types of diabetes. After independent screening, the characteristics of the eligible measures including design and severity domains, the clinical utility of developed measures, and the relationship between severity levels and health-related outcomes were assessed.

RESULTS

We identified 6798 studies, of which 17 studies reporting 18 different severity measures (32 314 participants in 17 countries) were included: a diabetes severity index (eight studies, 44%); severity categories (seven studies, 39%); complication count (two studies, 11%); and a severity checklist (one study, 6%). Nearly 89% of the measures included diabetes-related complications and/or glycaemic control indicators. Two of the severity measures were validated in a separate study population. More severe diabetes was associated with increased healthcare costs, poorer cognitive function and significantly greater risks of hospitalization and mortality. The identified measures differed greatly in terms of the included domains. One study reported on the use of a severity measure prospectively.

CONCLUSIONS

Health records are suitable for assessment of diabetes severity; however, the clinical uptake of existing measures is limited. The need to advance this research area is fundamental as higher levels of diabetes severity are associated with greater risks of adverse outcomes. Diabetes severity assessment could help identify people requiring targeted and intensive therapies and provide a major benchmark for efficient healthcare services.

Fine Mapping of Lr49 Using 90K SNP Chip Array and Flow-Sorted Chromosome Sequencing in Wheat

Leaf rust, caused by Puccinia triticina, threatens global wheat production due to the constant evolution of virulent pathotypes that defeat commercially deployed all stage-resistance (ASR) genes in modern cultivars. Hence, the deployment of combinations of adult plant resistance (APR) and ASR genes in new wheat cultivars is desirable. Adult plant resistance gene Lr49 was previously mapped on the long arm of chromosome 4B of cultivar VL404 and flanked by microsatellite markers barc163 (8.1 cM) and wmc349 (10.1 cM), neither of which was sufficiently closely linked for efficient marker assisted selection. This study used high-density SNP genotyping and flow sorted chromosome sequencing to fine-map the Lr49 locus as a starting point to develop a diagnostic marker for use in breeding and to clone this gene. Marker sunKASP_21 was mapped 0.4 cM proximal to Lr49, whereas a group of markers including sunKASP_24 were placed 0.6 cM distal to this gene. Testing of the linked markers on 75 Australian and 90 European cultivars with diverse genetic backgrounds showed that sunKASP_21 was most strongly associated with Lr49. Our results also show that the Lr49 genomic region contains structural variation relative to the reference stock Chinese Spring, possibly an inverted genomic duplication, which introduces a new set of challenges for the Lr49 cloning.

Characterisation and mapping of adult plant stripe rust resistance in wheat accession Aus27284

A new adult plant stripe rust resistance gene, Yr80, was identified in a common wheat landrace Aus27284. Linked markers were developed and validated for their utility in marker-assisted selection. Stripe rust, caused by Puccinia striiformis f. sp. tritici (Pst), is among the most important constraints to global wheat production. The identification and characterisation of new sources of host plant resistance enrich the gene pool and underpin deployment of resistance gene pyramids in new cultivars. Aus27284 exhibited resistance at the adult plant stage against predominant Pst pathotypes and was crossed with a susceptible genotype Avocet S. A recombinant inbred line (RIL) population comprising 121 lines was developed and tested in the field at three locations in 2016 and two in 2017 crop seasons. Monogenic segregation for adult plant stripe rust response was observed among the Aus27284/Avocet S RIL population and the underlying locus was temporarily designated YrAW11. Bulked-segregant analysis using the Infinium iSelect 90K SNP wheat array placed YrAW11 in chromosome 3B. Kompetitive allele specific PCR (KASP) primers were designed for the linked SNPs and YrAW11 was flanked by KASP_65624 and KASP_53292 (3 cM) proximally and KASP_53113 (4.9 cM) distally. A partial linkage map of the genomic region carrying YrAW11 comprised nine KASP and two SSR markers. The physical position of KASP markers in the pseudomolecule of chromosome 3B placed YrAW11 in the long arm and the location of markers gwm108 and gwm376 in the deletion bin 3BL2-0.22 supported this conclusion. As no other stripe rust resistance locus has been reported in chromosome 3BL, YrAW11 was formally designated Yr80. Marker KASP_ 53113 was polymorphic among 94% of 81 Australian wheat cultivars used for validation.