Genetic factors underlying host resistance to Rhipicephalus microplus tick infestation in Braford cattle: a systems biology perspective.

Approximately 80% of the world's cattle are raised in regions with a high risk of tick-borne diseases, resulting in significant economic losses due to parasitism by Rhipicephalus (Boophilus) microplus. However, the lack of a systemic biology approach hampers a comprehensive understanding of tick-host interactions that mediate tick resistance phenotypes. Here, we conducted a genome-wide association study (GWAS) of 2933 Braford cattle and found 340 single-nucleotide polymorphisms (SNPs) associated with tick counts. Gene expression analyses were performed on skin samples obtained from previously tick-exposed heifers with extremely high or low estimated breeding values for R. microplus counts. Evaluations were performed both before and after artificial infestation with ticks. Differentially expressed genes were found within 1-Mb windows centered at significant SNPs from GWAS. A total of 330 genes were related to the breakdown of homeostasis that was induced by larval attachment to bovine skin. Enrichment analysis pointed to a key role of proteolysis and signal transduction via JAK/STAT, NFKB and WNT/beta catenin signaling pathways. Integrative analysis on matrixEQTL revealed two cis-eQTLs and four significant SNPs in the genes peptidyl arginine deiminase type IV (PADI4) and LOC11449251. The integration of genomic data from QTL maps and transcriptome analyses has identified a set of twelve key genes that show significant associations with tick loads. These genes could be key candidates to improve the accuracy of genomic predictions for tick resistance in Braford cattle.

Imaging associations enhance the understanding of ECG abnormalities in male Brazilian football players: findings from the B-Pro Foot ECG study.

OBJECTIVES: To evaluate the prevalence of abnormal ECG findings and their association with imaging results in male Brazilian football players. METHODS: The 'B-Pro Foot ECG' is a multicentre observational study conducted in 82 Brazilian professional clubs. It analysed 6125 players aged 15-35 years (2496 white, 2004 mixed-race and 1625 black individuals) who underwent cardiovascular screening from 2002 to 2023. All ECGs were reviewed by two experienced cardiologists in the athlete's care. Those with abnormal findings underwent further investigations, including a transthoracic echocardiogram (TTE). Cardiac magnetic resonance (CMR) was subsequently performed based on TTE findings or clinical suspicion. RESULTS: In total, 180 (3%) players had abnormal ECGs and 176 (98%) showed normal TTE results. Athletes aged 26-35 years had a higher prevalence of abnormal ECGs than younger athletes (15-25 years). Black players had a higher prevalence of T-wave inversion (TWI) in the inferior leads than white players (2.6% vs 1.4%; p=0.005), as well as in V5 (2.9%) and V6 (2.1%) compared with white (1.2% and 1.0%; p<0.001) and mixed-race (1.5% and 1.2%; p<0.05) players, respectively. TTE parameters were similar across ethnicities. However, four out of 75 players with inferolateral TWI showed abnormal TTEs and CMR findings consistent with cardiomyopathies. CMR also showed cardiomyopathies or myocarditis in four players with inferolateral TWI and normal TTEs. In total, nine (0.1%) athletes were diagnosed with cardiac diseases and were followed for 40±30 months, with no cardiac events documented. CONCLUSION: This study found a 3% prevalence of abnormal ECGs in male Brazilian football players. Inferolateral TWI was associated with cardiac pathologies confirmed by CMR, even in athletes with a normal TTE.

Tag SNP selection for prediction of adaptation traits in Braford and Hereford cattle using Bayesian methods.

This study utilized Bayesian inference in a genome-wide association study (GWAS) to identify genetic markers associated with traits relevant to the adaptation of Hereford and Braford cattle breeds. We focused on eye pigmentation (EP), weaning hair coat (WHC), yearling hair coat (YHC), and breeding standard (BS). Our dataset comprised 126,290 animals in the pedigree. Out of these, 233 sires were genotyped using high-density (HD) chips, and 3750 animals with medium-density (50 K) single-nucleotide polymorphism (SNP) chips. Employing the Bayes B method with a prior probability of π = 0.99, we identified and tagged single nucleotide polymorphisms (Tag SNPs), ranging from 18 to 117 SNPs depending on the trait. These Tag SNPs facilitated the construction of reduced SNP panels. We then evaluated the predictive accuracy of these panels in comparison to traditional medium-density SNP chips. The accuracy of genomic predictions using these reduced panels varied significantly depending on the clustering method, ranging from 0.13 to 0.65. Additionally, we conducted functional enrichment analysis that found genes associated with the most informative SNP markers in the current study, thereby providing biological insights into the genomic basis of these traits.

An HIV-1/HIV-2 Chimeric Envelope Glycoprotein Generates Binding and Neutralising Antibodies against HIV-1 and HIV-2 Isolates.

The development of immunogens that elicit broadly reactive neutralising antibodies (bNAbs) is the highest priority for an HIV vaccine. We have shown that a prime-boost vaccination strategy with vaccinia virus expressing the envelope glycoprotein gp120 of HIV-2 and a polypeptide comprising the envelope regions C2, V3 and C3 elicits bNAbs against HIV-2. We hypothesised that a chimeric envelope gp120 containing the C2, V3 and C3 regions of HIV-2 and the remaining parts of HIV-1 would elicit a neutralising response against HIV-1 and HIV-2. This chimeric envelope was synthesised and expressed in vaccinia virus. Balb/c mice primed with the recombinant vaccinia virus and boosted with an HIV-2 C2V3C3 polypeptide or monomeric gp120 from a CRF01_AG HIV-1 isolate produced antibodies that neutralised >60% (serum dilution 1:40) of a primary HIV-2 isolate. Four out of nine mice also produced antibodies that neutralised at least one HIV-1 isolate. Neutralising epitope specificity was assessed using a panel of HIV-1 TRO.11 pseudoviruses with key neutralising epitopes disrupted by alanine substitution (N160A in V2; N278A in the CD4 binding site region; N332A in the high mannose patch). The neutralisation of the mutant pseudoviruses was reduced or abolished in one mouse, suggesting that neutralising antibodies target the three major neutralising epitopes in the HIV-1 envelope gp120. These results provide proof of concept for chimeric HIV-1/HIV-2 envelope glycoproteins as vaccine immunogens that can direct the antibody response against neutralising epitopes in the HIV-1 and HIV-2 surface glycoproteins.

Association between menopausal symptoms, sexual function, and sexual activity - a cross-sectional study.

Introduction: To analyse the possible association between menopausal symptoms (somatic-vegetative, psychological, and urogenital) and sexual function with the maintenance of the sexual activity of women in menopause. Material and methods: This cross-sectional study comprised 96 menopausal women aged 40-59 (52.88 ±4.05) years, who presented a positive score to the menopause rating scale (MRS) and had serum levels of follicle stimulating hormone ≥ 25 IU/ml. Participants who used hormone replacement therapy were excluded. Results: It was observed that participants who had an active sexual life had lower medians in the somatic-vegetative (p < 0.001) and psychological symptoms (p = 0.006), as well as in the general score (p = 0.001) at the MRS; in addition, they had better sexual function in 4 domains (p < 0.005): excitement, lubrication, orgasm, and pain, as well as in the total score of the female sexual function index questionnaire (p < 0.005). It was also found that, regardless of the type of menopause (surgical or natural), women who did not engage in sexual activity had a score of 5.651 points more in the MRS (p = 0.004), demonstrating that the practice of sexual activity predicts in 10.4% the variation in the symptom score. Conclusions: Menopausal women who maintain sexual activity had a lower score on the menopause symptom score and better sexual function compared to those who did not perform sexual activity.

Detection of anti-Pneumocystis jirovecii antibodies in human serum using a recombinant synthetic multi-epitope kexin-based antigen.

Interest in the detection of specific anti-Pneumocystis jirovecii antibodies has emerged as less-invasive alternative diagnostic approaches. Here is presented the performance of an ELISA based on a recombinant synthetic multi-epitope kexin 1 (Kex1) antigen of P. jirovecii, previously developed. Results showed that IgM anti-Kex1 levels were found significantly increased in patients with Pneumocystis pneumonia (PcP) compared with non-PcP cases (p < 0.001), allowing a diagnostic performance of PcP with a 70.8% sensitivity and a 75.0% specificity. These results suggest that this Kex1-based ELISA is a promising tool toward the serodiagnosis of PcP when the standard methods are difficult to perform.

Adherence and effectiveness of a single instruction of pelvic floor exercises: a randomized clinical trial.

INTRODUCTION AND HYPOTHESIS: In Brazil there are limited knowledge and education about preventative exercises for pelvic floor muscles (PFMs). We hypothesised that a single pelvic floor muscle exercise (PFME) session immediately postpartum would be effective in preventing urinary incontinence (UI) in a 3-month postpartum period with good adherence rates. METHODS: Two hundred two women were approached for this randomised controlled trial and randomly assigned to two groups: the control group and experimental group. The intervention comprised a visual assessment of PFM contraction, a single PFME instruction session supervised by a physical therapist, and an educational approach through distribution of brochures about home-based PFME exercises (without supervision). Involuntary urinary loss and quality of life (QoL) were evaluated using the International Consultation on Incontinence Questionnaire Short Form (main outcome). Sociodemographic and clinical information was collected. Adherence and barriers were assessed via telephone/mobile phone surveys (secondary outcomes). RESULTS: The adherence rate was 85.1%; only 37% of the women reported having some knowledge about PFME prior to participating in this study. The main barriers to PFME mentioned were forgetfulness (61.2%), lack of time (52.2%), and the need to take care of the baby (56.7%). One instruction session on postnatal PFME delivered in the immediate postpartum period was ineffective for improving urinary symptoms such as frequency of leakage (p = 0.821), amount of leakage (p = 0.746), and influence of leakage on QoL (p = 0.823). In addition, there was no difference in QoL 3 months post-partum (p = 0.872). CONCLUSIONS: Although the proposed intervention did not prevent UI symptoms, the adherence rate to PFME was high.

Tag-SNP selection using Bayesian genomewide association study for growth traits in Hereford and Braford cattle.

The aim of this study was to perform a Bayesian genomewide association study (GWAS) to identify genomic regions associated with growth traits in Hereford and Braford cattle, and to select Tag-SNPs to represent these regions in low-density panels useful for genomic predictions. In addition, we propose candidate genes through functional enrichment analysis associated with growth traits using Medical Subject Headings (MeSH). Phenotypic data from 126,290 animals and genotypes for 131 sires and 3,545 animals were used. The Tag-SNPs were selected with BayesB (π = 0.995) method to compose low-density panels. The number of Tag-single nucleotide polymorphism (SNP) ranged between 79 and 103 SNP for the growth traits at weaning and between 78 and 100 SNP for the yearling growth traits. The average proportion of variance explained by Tag-SNP with BayesA was 0.29, 0.23, 0.32 and 0.19 for birthweight (BW), weaning weight (WW205), yearling weight (YW550) and postweaning gain (PWG345), respectively. For Tag-SNP with BayesA method accuracy values ranged from 0.13 to 0.30 for k-means and from 0.30 to 0.65 for random clustering of animals to compose reference and validation groups. Although genomic prediction accuracies were higher with the full marker panel, predictions with low-density panels retained on average 76% of the accuracy obtained with BayesB with full markers for growth traits. The MeSH analysis was able to translate genomic information providing biological meanings of more specific gene products related to the growth traits. The proposed Tag-SNP panels may be useful for future fine mapping studies and for lower-cost commercial genomic prediction applications.

Breeding objectives of Brangus cattle in Brazil.

Our goal was to define a breeding objective for Brangus beef cattle in Brazil. Bioeconomic models were produced and used to estimate economic values (EVs). The scenarios simulated were typical full-cycle beef production systems that are used in tropical and subtropical regions. The breeding objective contained pregnancy rate (PR), warm carcass weight (WCW), mature cow weight (MCW), number of nematode eggs per gram of faeces (EPG) and tick count (TICK). Two models were used in series to estimate the EV. A deterministic model was used to simulate effects of PR, WCW and MCW on profitability with a constant parasite load. Subsequently, stochastic models were used to estimate economic values for TICK and EPG as consequences of their environmental effects on weight gains, mortality and health costs. The EV of PR, WCW, MCW, EPG and TICK, was US$1.59, US$2.11, -US$0.24, -US$5.35 and -US$20.88, respectively. Results indicate positive emphasis should be placed on PR (12.49%) and WCW (65.07%) with negative emphasis on MCW (13.92%), EPG (2.77%) and TICK (5.75%). In comparison with the indexes usually used, these results suggest a reformulation in the selection indexes of the beef production system in tropical and subtropical regions in order to obtain greater profitability.

Genetic differences among Moraxella bovis and Moraxella bovoculi isolates from infectious bovine keratoconjunctivitis (IBK) outbreaks in southern Brazil.

The objective of this study was to evaluate the genetic diversity of Moraxella bovis and Moraxella bovoculi bacteria isolated from infectious bovine keratoconjunctivitis (IBK) outbreaks in the state of Rio Grande do Sul, Brazil. The genetic diversity among Moraxella spp. was evaluated by RAPD-PCR, JWP1-JWOPA07-PCR, ERIC-PCR and by sequencing the 16S-23S intergenic regions. Based on the dendrogram, two genetically differentiated clades were observed; 14 isolates were classified as M. bovis and 17 as M. bovoculi. Genetic distances between the M. bovis samples ranged from 0.0379 to 0.4285, while for M. bovoculi the dissimilarities ranged from zero to 0.7297. Alternatively, based on sequencing analyses of the 16S-23S intergenic region, M. bovis and M. bovoculi isolates were grouped into the same two different clades, but it was not possible to differentiate between isolates within clades. PCR techniques were demonstrated to be a satisfactory tool to unravel the genetic variability among Moraxella spp., while sequencing of the 16S-23S intergenic region was only able to differentiate two species of the Moraxella genus. Despite sampling geographically close regions, we demonstrate considerable genetic diversity in M. bovis and M. bovoculi strains and genetically distinct M. bovis strains co-infecting the same animal.

Network analysis uncovers putative genes affecting resistance to tick infestation in Braford cattle skin.

BACKGROUND: Genetic resistance in cattle is considered a suitable way to control tick burden and its consequent losses for livestock production. Exploring tick-resistant (R) and tick-susceptible (S) hosts, we investigated the genetic mechanisms underlying the variation of Braford resistance to tick infestation. Skin biopsies from four-times-artificially infested R (n = 20) and S (n = 19) hosts, obtained before the first and 24 h after the fourth tick infestation were submitted to RNA-Sequencing. Differential gene expression, functional enrichment, and network analysis were performed to identify genetic pathways and transcription factors (TFs) affecting host resistance. RESULTS: Intergroup comparisons of hosts before (Rpre vs. Spre) and after (Rpost vs. Spost) tick infestation found 51 differentially expressed genes (DEGs), of which almost all presented high variation (TopDEGs), and 38 were redundant genes. Gene expression was consistently different between R and S hosts, suggesting the existence of specific anti-tick mechanisms. In the intragroup comparisons, Rpost vs. Rpre and Spost vs. Spre, we found more than two thousand DEGs in response to tick infestation in both resistance groups. Redundant and non-redundant TopDEGs with potential anti-tick functions suggested a role in the development of different levels of resistance within the same breed. Leukocyte chemotaxis was over-represented in both hosts, whereas skin degradation and remodeling were only found in TopDEGs from R hosts. Also, these genes indicated the participation of cytokines, such as IL6 and IL22, and the activation of Wingless (WNT)-signaling pathway. A central gene of this pathway, WNT7A, was consistently modulated when hosts were compared. Moreover, the findings based on a genome-wide association study (GWAS) corroborate the prediction of the WNT-signaling pathway as a candidate mechanism of resistance. The regulation of immune response was the most relevant pathway predicted for S hosts. Members of Ap1 and NF-kB families were the most relevant TFs predicted for R and S, respectively. CONCLUSION: This work provides indications of genetic mechanisms presented by Braford cattle with different levels of resistance in response to tick infestation, contributing to the search of candidate genes for tick resistance in bovine.

Frequentist p-values for large-scale-single step genome-wide association, with an application to birth weight in American Angus cattle.

BACKGROUND: Single-step genomic best linear unbiased prediction (SSGBLUP) is a comprehensive method for genomic prediction. Point estimates of marker effects from SSGBLUP are often used for genome-wide association studies (GWAS) without a formal framework of hypothesis testing. Our objective was to implement p-values for single-marker GWAS studies within the single-step GWAS (SSGWAS) framework by deriving computational algorithms and procedures, and by applying these to a large beef cattle population. METHODS: P-values were obtained based on the prediction error (co)variances for single nucleotide polymorphisms (SNPs), which were obtained from the prediction error (co)variances of genomic predictions based on the inverse of the coefficient matrix and formulas to estimate SNP effects. RESULTS: Computation of p-values took a negligible time for a dataset with almost 2 million animals in the pedigree and 1424 genotyped sires, and no inflation of statistics was observed. The SNPs that passed the Bonferroni threshold of 10-5.9 were the same as those that explained the highest proportion of additive genetic variance, but even at the same significance levels and effects, some of them explained less genetic variance due to lower allele frequency. CONCLUSIONS: The use of a p-value for SSGWAS is a very general and efficient strategy to identify quantitative trait loci (QTL). It can be used for complex datasets such as those used in animal breeding, where only a proportion of the pedigreed animals are genotyped.

Economic selection index in small rural dairy farms.

This study aimed to calculate economic values (EVs) and economic selection indices for milk production systems in small rural properties. The traits 305-d milk yield in kg (MY), fat (FP) and protein (PP) percentage, daily fat (FY) and protein (PY) yield, cow live weight in kg (LW), calving interval (CI), and logarithm of daily somatic cell count (SCC) in milk were considered the goals and selection criteria. The production systems were identified from 29 commercial properties based on the inventory of revenues and costs and of zootechnical field data. Later, bioeconomic models were developed to calculate the productive performance, revenues, and costs concerning milk production to estimate EVs, which were calculated as the difference in annual profit with dairy production resulting from a change in one unit of the trait while keeping the others constant and dividing the value by the number of cows. After the EVs were known, ten economic selection indices were estimated for each system so they could be compared by modifying the selection criteria and calculating the relative importance of each selection criteria, the accuracy of the economic selection index, and response expected to the selection in USD, among other parameters. One of the systems detected was called less intensive (LS) and was characterized by having ten cows in lactation that produced 13·5 l/d and consumed 1·8 kg of concentrate/d. The second system detected was called more intensive (IS) and had 22 cows in lactation that produced 17·5 l/d and consumed 3·4 kg of concentrate/d. Monthly profits per cows in lactation of USD 2·60 and USD 68·77 were recorded for LS and IS, respectively. The EVs of the traits MY, FP, and PP were all positive, while for the other traits they were all negative in all situations. The best economic selection indices were those featuring selection criteria MY, LW, and CI, while the trait LW had the greatest importance in both systems. These results indicate that animal frame must be controlled in order to maximize the system's profit.

The Effect of Chronic Musculoskeletal Pain on Sexual Function and Quality of Life of Cardiac Rehabilitation Patients.

BACKGROUND: Comorbidities are stressors to the body and have a negative impact on quality of life and sexual function. OBJECTIVE: The objective of this study was to investigate the effect of the coexistence of coronary heart disease and chronic musculoskeletal pain on sexual function and quality of life of patients undergoing an exercise-based cardiac rehabilitation program. METHODS: This cross-sectional observational study included 105 patients. Instruments used were the musculoskeletal system assessment inventory, Short-Form Health Survey quality-of-life questionnaire, International Index of Erectile Function, and Female Sexual Function Index. RESULTS: There were no differences in male sexual function compared between participants with and without pain. Participants with pain had lower quality-of-life scores related to socioemotional aspects. CONCLUSIONS: The coexistence of coronary heart disease and musculoskeletal pain does not seem to affect patients' sexual function, but it negatively affects Patients' quality of life. This study emphasizes the importance of a multidisciplinary team working in a cardiac rehabilitation program addressing issues related to pain, sexual function, and quality of life.

Genomic predictions for economically important traits in Brazilian Braford and Hereford beef cattle using true and imputed genotypes.

BACKGROUND: Genomic selection (GS) has played an important role in cattle breeding programs. However, genotyping prices are still a challenge for implementation of GS in beef cattle and there is still a lack of information about the use of low-density Single Nucleotide Polymorphisms (SNP) chip panels for genomic predictions in breeds such as Brazilian Braford and Hereford. Therefore, this study investigated the effect of using imputed genotypes in the accuracy of genomic predictions for twenty economically important traits in Brazilian Braford and Hereford beef cattle. Various scenarios composed by different percentages of animals with imputed genotypes and different sizes of the training population were compared. De-regressed EBVs (estimated breeding values) were used as pseudo-phenotypes in a Genomic Best Linear Unbiased Prediction (GBLUP) model using two different mimicked panels derived from the 50 K (8 K and 15 K SNP panels), which were subsequently imputed to the 50 K panel. In addition, genomic prediction accuracies generated from a 777 K SNP (imputed from the 50 K SNP) were presented as another alternate scenario. RESULTS: The accuracy of genomic breeding values averaged over the twenty traits ranged from 0.38 to 0.40 across the different scenarios. The average losses in expected genomic estimated breeding values (GEBV) accuracy (accuracy obtained from the inverse of the mixed model equations) relative to the true 50 K genotypes ranged from -0.0007 to -0.0012 and from -0.0002 to -0.0005 when using the 50 K imputed from the 8 K or 15 K, respectively. When using the imputed 777 K panel the average losses in expected GEBV accuracy was -0.0021. The average gain in expected EBVs accuracy by including genomic information when compared to simple BLUP was between 0.02 and 0.03 across scenarios and traits. CONCLUSIONS: The percentage of animals with imputed genotypes in the training population did not significantly influence the validation accuracy. However, the size of the training population played a major role in the accuracies of genomic predictions in this population. The losses in the expected accuracies of GEBV due to imputation of genotypes were lower when using the 50 K SNP chip panel imputed from the 15 K compared to the one imputed from the 8 K SNP chip panel.

Tag SNP selection for prediction of tick resistance in Brazilian Braford and Hereford cattle breeds using Bayesian methods.

BACKGROUND: Cattle resistance to ticks is known to be under genetic control with a complex biological mechanism within and among breeds. Our aim was to identify genomic segments and tag single nucleotide polymorphisms (SNPs) associated with tick-resistance in Hereford and Braford cattle. The predictive performance of a very low-density tag SNP panel was estimated and compared with results obtained with a 50 K SNP dataset. RESULTS: BayesB (π = 0.99) was initially applied in a genome-wide association study (GWAS) for this complex trait by using deregressed estimated breeding values for tick counts and 41,045 SNP genotypes from 3455 animals raised in southern Brazil. To estimate the combined effect of a genomic region that is potentially associated with quantitative trait loci (QTL), 2519 non-overlapping 1-Mb windows that varied in SNP number were defined, with the top 48 windows including 914 SNPs and explaining more than 20% of the estimated genetic variance for tick resistance. Subsequently, the most informative SNPs were selected based on Bayesian parameters (model frequency and t-like statistics), linkage disequilibrium and minor allele frequency to propose a very low-density 58-SNP panel. Some of these tag SNPs mapped close to or within genes and pseudogenes that are functionally related to tick resistance. Prediction ability of this SNP panel was investigated by cross-validation using K-means and random clustering and a BayesA model to predict direct genomic values. Accuracies from these cross-validations were 0.27 ± 0.09 and 0.30 ± 0.09 for the K-means and random clustering groups, respectively, compared to respective values of 0.37 ± 0.08 and 0.43 ± 0.08 when using all 41,045 SNPs and BayesB with π = 0.99, or of 0.28 ± 0.07 and 0.40 ± 0.08 with π = 0.999. CONCLUSIONS: Bayesian GWAS model parameters can be used to select tag SNPs for a very low-density panel, which will include SNPs that are potentially linked to functional genes. It can be useful for cost-effective genomic selection tools, when one or a few key complex traits are of interest.

Reference values for the incremental shuttle walk test in patients with cardiovascular disease entering exercise-based cardiac rehabilitation.

The incremental shuttle walk test (ISWT) is used to assess functional capacity of patients entering cardiac rehabilitation. Factors such as age and sex account for a proportion of the variance in test performance in healthy individuals but there are no reference values for patients with cardiovascular disease. The aim of this study was to produce reference values for the ISWT. Participants were n = 548 patients referred to outpatient cardiac rehabilitation who underwent a clinical examination and performed the ISWT. We used regression to identify predictors of performance and produced centile values using the generalised additive model for location, scale and shape model. Men walked significantly further than women (395 ± 165 vs. 269 ± 118 m; t = 9.5, P < 0.001) so data were analysed separately by sex. Age (years) was the strongest predictor of performance in men (ß = -5.9; 95% CI: -7.1 to -4.6 m) and women (ß = -4.8; 95% CI: -6.3 to 3.3). Centile curves demonstrated a broadly linear decrease in expected ISWT values in males (25-85 years) and a more curvilinear trend in females. Patients entering cardiac rehabilitation present with highly heterogeneous ISWT values. Much of the variance in performance can be explained by patients' age and sex. Comparing absolute values with age-and sex-specific reference values may aid interpretation of ISWT performance during initial patient assessment at entry to cardiac rehabilitation.

Linkage disequilibrium, persistence of phase and effective population size estimates in Hereford and Braford cattle.

BACKGROUND: The existence of moderate to high levels of linkage disequilibrium (LD) between genetic markers and quantitative trait loci (QTL) affecting traits of interest is fundamental for the success of genome-wide association (GWAS) and genomic selection (GS) studies. Knowledge about the extent and the pattern of LD in livestock populations is essential to determine the density of single nucleotide polymorphisms (SNP) required for accurate GWAS and GS. Moreover, observed LD is related to historical effective population sizes (Ne), and can provide insights into the genetic diversity history of populations. Estimates of the consistency of linkage phase across breeds (R H,B ) can be used to determine if there is sufficient relationship to use pooled reference populations in multi-breed GS programs. The objective of this study was to estimate LD levels, persistence of phase and effective population size in Hereford and Braford cattle populations sampled in Brazil. RESULTS: Mean LD estimates, measured using the squared correlation of alleles at two loci (r (2)), obtained between adjacent SNP across all chromosomes were 0.21 ± 0.27 for Herefords (391 samples with 41,241 SNP) and 0.16 ± 0.22 for Brafords (2044 samples and 41,207 SNP). Estimated r(2) was > 0.2 and 0.3, respectively, for 34 and 25% of adjacent markers in Herefords, and 26 and 17% in Brafords. Estimated N e for Brafords and Herefords at the current generation was 220 and 153 individuals, respectively. The two breeds demonstrated moderate to strong persistence of phase at all distances (R H,B = 0.53 to 0.97). The largest phase correlations were found in the 0 to 50 Kb bins (R H,B = 0.92 to 0.97). Estimated LD decreased rapidly with increasing distance between SNP, however, useful linkage for GWAS and GS (r(2) > 0.2) was found spanning to ~50 Kb. CONCLUSIONS: Panels containing about 50,000 and 150,000 SNP markers are necessary to detect minimal levels of LD between adjacent markers that would be useful for GWAS and GS studies to Hereford and Braford breeds, respectively. Markers are expected to be linked to the same QTL alleles in distances < 50 Kb in both populations due to observed high persistence of phase levels.

Multigene characterization of a new 'Candidatus Phytoplasma rubi'-related strain associated with blackberry witches' broom.

A new phytoplasma was identified in naturally infected blackberry plants exhibiting witches' broom symptoms in Portugal. The 16S rRNA gene sequence revealed that it is related to 'Candidatus Phytoplasma rubi' (16SrV-E ribosomal subgroup) and RFLP analysis revealed a unique profile following MseI endonuclease digestion of R16F2n/R2 amplicons that distinguished it from the strains belonging to previously established 16SrV phytoplasma subgroups. The in silico restriction analyses confirmed that the phytoplasma strain from blackberry is different from all the other strains reported in group 16SrV. Phylogeny of the 16S rRNA gene sequences, sequence analyses of 16S-23S, tuf, rplV-rpsC, rplF-rplR, rplO-SecY-map and uvrB-degV genetic loci, as well as the variability of unique oligonucleotide sequences defined for 'Candidatus Phytoplasma rubi' confirmed the uniqueness of this phytoplasma strain from Portugal for which a novel ribosomal subgroup, 16SrV-I, is proposed. The representative of this new subgroup was named blackPort phytoplasma (Portuguese blackberry phytoplasma).

Genotype by environment interaction for tick resistance of Hereford and Braford beef cattle using reaction norm models.

BACKGROUND: The cattle tick is a parasite that adversely affects livestock performance in tropical areas. Although countries such as Australia and Brazil have developed genetic evaluations for tick resistance, these evaluations have not considered genotype by environment (G*E) interactions. Genetic gains could be adversely affected, since breedstock comparisons are environmentally dependent on the presence of G*E interactions, particularly if residual variability is also heterogeneous across environments. The objective of this study was to infer upon the existence of G*E interactions for tick resistance of cattle based on various models with different assumptions of genetic and residual variability. METHODS: Data were collected by the Delta G Connection Improvement program and included 10,673 records of tick counts on 4363 animals. Twelve models, including three traditional animal models (AM) and nine different hierarchical Bayesian reaction norm models (HBRNM), were investigated. One-step models that jointly estimate environmental covariates and reaction norms and two-step models based on previously estimated environmental covariates were used to infer upon G*E interactions. Model choice was based on the deviance criterion information. RESULTS: The best-fitting model specified heterogeneous residual variances across 10 subclasses that were bounded by every decile of the contemporary group (CG) estimates of tick count effects. One-step models generally had the highest estimated genetic variances. Heritability estimates were normally higher for HBRNM than for AM. One-step models based on heterogeneous residual variances also usually led to higher heritability estimates. Estimates of repeatability varied along the environmental gradient (ranging from 0.18 to 0.45), which implies that the relative importance of additive and permanent environmental effects for tick resistance is influenced by the environment. Estimated genetic correlations decreased as the tick infestation level increased, with negative correlations between extreme environmental levels, i.e., between more favorable (low infestation) and harsh environments (high infestation). CONCLUSIONS: HBRNM can be used to describe the presence of G*E interactions for tick resistance in Hereford and Braford beef cattle. The preferred model for the genetic evaluation of this population for tick counts in Brazilian climates was a one-step model that considered heteroscedastic residual variance. Reaction norm models are a powerful tool to identify and quantify G*E interactions and represent a promising alternative for genetic evaluation of tick resistance, since they are expected to lead to greater selection efficiency and genetic progress.