Genome-Wide Association (GWAS) Applied to Carcass and Meat Traits of Nellore Cattle

The meat market has enormous importance for the world economy, and the quality of the product offered to the consumer is fundamental for the success of the sector. In this study, we analyzed a database which contained information on 2470 animals from a commercial farm in the state of São Paulo, Brazil. Of this total, 2181 animals were genotyped, using 777,962 single-nucleotide polymorphisms (SNPs). After quality control analysis, 468,321 SNPs provided information on the number of genotyped animals. Genome-wide association analyses (GWAS) were performed for the characteristics of the rib eye area (REA), subcutaneous fat thickness (SFT), shear force at 7 days' ageing (SF7), and intramuscular fat (IMF), with the aid of the single-step genomic best linear unbiased prediction (ssGBLUP) method, with the purpose of identifying possible genomic windows (~1 Mb) responsible for explaining at least 0.5% of the genetic variance of the traits under analysis (≥0.5%). These genomic regions were used in a gene search and enrichment analyses using MeSH terms. The distributed heritability coefficients were 0.14, 0.20, 0.18, and 0.21 for REA, SFT, SF7, and IMF, respectively. The GWAS results indicated significant genomic windows for the traits of interest in a total of 17 chromosomes. Enrichment analyses showed the following significant terms (FDR ≤ 0.05) associated with the characteristics under study: for the REA, heat stress disorders and life cycle stages; for SFT, insulin and nonesterified fatty acids; for SF7, apoptosis and heat shock proteins (HSP27); and for IMF, metalloproteinase 2. In addition, KEGG (Kyoto encyclopedia of genes and genomes) enrichment analysis allowed us to highlight important metabolic pathways related to the studied phenotypes, such as the growth hormone synthesis, insulin-signaling, fatty acid metabolism, and ABC transporter pathways. The results obtained provide a better understanding of the molecular processes involved in the expression of the studied characteristics and may contribute to the design of selection strategies and future studies aimed at improving the productivity of Nellore cattle.

Copy number variations and genome-wide associations reveal putative genes and metabolic pathways involved with the feed conversion ratio in beef cattle

The use of genome-wide association results combined with other genomic approaches may uncover genes and metabolic pathways related to complex traits. In this study, the phenotypic and genotypic data of 1475 Nellore (Bos indicus) cattle and 941,033 single nucleotide polymorphisms (SNPs) were used for genome-wide association study (GWAS) and copy number variations (CNVs) analysis in order to identify candidate genes and putative pathways involved with the feed conversion ratio (FCR). The GWAS was based on the Bayes B approach analyzing genomic windows with multiple regression models to estimate the proportion of genetic variance explained by each window. The CNVs were detected with PennCNV software using the log R ratio and B allele frequency data. CNV regions (CNVRs) were identified with CNVRuler and a linear regression was used to associate CNVRs and the FCR. Functional annotation of associated genomic regions was performed with the Database for Annotation, Visualization and Integrated Discovery (DAVID) and the metabolic pathways were obtained from the Kyoto Encyclopedia of Genes and Genomes (KEGG). We showed five genomic windows distributed over chromosomes 4, 6, 7, 8, and 24 that explain 12 % of the total genetic variance for FCR, and detected 12 CNVRs (chromosomes 1, 5, 7, 10, and 12) significantly associated [false discovery rate (FDR) < 0.05] with the FCR. Significant genomic regions (GWAS and CNV) harbor candidate genes involved in pathways related to energetic, lipid, and protein metabolism. The metabolic pathways found in this study are related to processes directly connected to feed efficiency in beef cattle. It was observed that, even though different genomic regions and genes were found between the two approaches (GWAS and CNV), the metabolic processes covered were related to each other. Therefore, a combination of the approaches complement each other and lead to a better understanding of the FCR.

Heat shock and structural proteins associated with meat tenderness in Nellore beef cattle, a Bos indicus breed

Nellore beef cattle, a Bos indicus (Zebu) breed, is well adapted to tropical conditions and has allowed Brazil to become one of the largest producers of red meat. Nevertheless, B. indicus breeds are reported to have less tender meat than Bos taurus. This study was designed to identify genes associated with meat tenderness and thus provides important information for breeding programs. A group of 138 animals was evaluated for longissimus thoracis muscle shear force (SF). Animals with the highest and lowest SF values (six animals each) were then selected for protein abundance studies. Samples were subjected to two-dimensional gel electrophoresis (2-DE) followed by peptide sequencing through mass spectrometry (MS) to identify differentially expressed proteins associated with SF values. Seventeen differentially expressed spots were observed (p<0.05) between the two groups. The 13 proteins identified included structural proteins (alpha actin-1, MLC1, MLC3, MLC2F and tropomyosin), related to cell organization (HSPB1 and HSP70), metabolism (beta-LG, ACBD6 and Complex III subunit I) and some uncharacterized proteins. Results confirm the existence of differentially expressed proteins associated with SF, which can lead to a better understanding of mechanisms involved in meat tenderness.

Protein synthesis and degradation gene SNPs related to feed intake, feed efficiency, growth, and ultrasound carcass traits in Nellore cattle

We looked for possible associations of SNPs in genes related to protein turnover, with growth, feed efficiency and carcass traits in feedlot Nellore cattle. Purebred Nellore bulls and steers (N = 290; 378 ± 42 kg body weight, 23 months ± 42 days old) were evaluated for daily feed intake, body weight gain (BWG), gross feed efficiency, feed conversion ratio, partial efficiency of growth, residual feed intake (RFI), ultrasound backfat, rump fat, and ribeye area. Genotypes were obtained for SNPs in the growth hormone receptor (GHR-1 and GHR-2); calpain (CAPN4751); calpastatin (UoGCAST); ubiquitin-conjugating enzyme 2I (UBE2I-1 and UBE2I-2); R3H domain containing 1 (R3HDM1-1, -2, -3, and -4), ring finger protein 19 (RNF19); proteasome 26S subunit, non-ATPase, 13 (PSMD13); ribosomal protein, large, P2 (RPLP2); and isoleucine-tRNA synthetase 2, mitochondrial (IARS2) genes. Allelic substitution, additive and dominant effects were tested and molecular breeding values were computed. CAPN4751, GHR-1 and -2, IARS2, R3HDM1-4, and UoGCAST were found to be normally segregating polymorphisms. Additive and dominance effects were observed on BWG, feed efficiency and carcass traits, although dominant effects predominated. Significant allelic substitution effects were observed for CAPN4751, GHR-1 and -2, and UoGCAST on BWG, gross feed efficiency, RFI, and carcass traits, under single- or multiple-marker analyses. Correlations between molecular breeding values and phenotypes were low, excepted for RFI, based on allelic substitution estimates obtained by stepwise linear regression. We conclude that SNPs in genes related to protein turnover are related to economically important traits in Nellore cattle.

Single nucleotide polymorphisms in CAPN and leptin genes associated with meat color and tenderness in Nellore cattle

We analyzed single nucleotide polymorphisms in calpain, leptin, leptin receptor, and growth hormone receptor genes and their association with color, drip and cooking losses of longissimus muscle at 7, 14 and 21 days postmortem in 638 purebred Nellore bulls slaughtered between 22 and 26 months of age. Meat samples were vacuum-packed and aged at 4°C. The single nucleotide polymorphisms T945M, GHR2, E2FB, and CAPN4751 were evaluated. All genotypic classes were observed; however, the T/T genotype of T945M and E2FB was found at a low frequency. A significant association of E2FB with drip loss (a measure of water-holding capacity) was detected at seven days of meat aging. CAPN4751 had an additive effect on red and yellow color intensities. The T allele of CAPN4751 was found to be positively associated with improved meat color, but not with meat tenderness, differing from a previous report indicating that it is associated with meat tenderness. We conclude that the potential for use of CAPN4751 as a marker for these meat quality traits requires further research.

[Triatoma infestans in area under entomological surveillance for Chagas' disease in São Paulo State, Brazil]

In response to notification of the capture of a winged triatomine bug by local inhabitants, an epidemiological investigation was investigated in the rural area of the Municipality of Paulínia, São Paulo State (Brazil). This led to the collection of 109 specimens of Triatoma infestans from peridomiciliary breeding sites. Local conditions favored colonization by triatomine bugs: many abandoned outbuildings were inhabited by pigeons and sparrows, which meant abundant feed for these bugs. Thus, surveillance is mandatory as long as conditions for triatomine breeding persist. Nevertheless, entomological and serological indicators ruled out immediate concern over vectorial transmission of Chagas' disease in this municipality. All domiciliary units of the region were sprayed with residual-effect insecticides and the triatomine breeding sites were destroyed by the use of mechanical control of bird nests. The importance of reporting the occurrence of triatomine bugs, particularly Triatoma infestans, in this region, is emphasized.

Hormonal and cardiovascular reflex assessment in a female patient with pure autonomic failure

We report the case of a 72-year-old female with pure autonomic failure, a rare entity, whose diagnosis of autonomic dysfunction was determined with a series of complementary tests. For approximately 2 years, the patient has been experiencing dizziness and a tendency to fall, a significant weight loss, generalized weakness, dysphagia, intestinal constipation, blurred vision, dry mouth, and changes in her voice. She underwent clinical assessment and laboratory tests (biochemical tests, chest X-ray, digestive endoscopy, colonoscopy, chest computed tomography, abdomen and pelvis computed tomography, abdominal ultrasound, and ambulatory blood pressure monitoring). Measurements of catecholamine and plasmatic renin activity were performed at rest and after physical exercise. Finally the patient underwent physiological and pharmacological autonomic tests that better diagnosed dysautonomia.

[Seroprevalence of Triatoma infestans Chagas disease after vector control measures]

INTRODUCTION

The study is part of a project intended to retrieve information about the serology of the American trypanosomiasis in the state of São Paulo, Brazil, during the period when there was a state effort to control the vector. Data from the municipality of Taquarituba, administrative region of Sorocaba, which was then important in the epidemiology of Chagas disease in that region, were analyzed. Despite the government efforts started in the 1950s, domiciliary triatomines were still being captured in that region during the 1970s.

METHODS

Population samples were selected from five localities of Taquarituba. Age, sex, birthplace, and time of residence in the house being occupied at the time of the interview, were recorded. It is used Probit analysis to assess a possible relationship between age and seropositivity, the latter taken as indicative of the risk of transmission.

RESULTS

Blood from Taquarituba native people represented 62.9% of the samples examined (n = 2.784) and 62.4% of all seropositives (n = 380). Overall proportion of seropositives was 13.6% with no significant difference between genders (p = 0.538). Children under 6 years of age were not seropovitive, Seropositivity increased from 2.7% in the age group 6-9 years to 30.6% in the age group 30-39 years. By using probit analysis, an age-seropositivity relationship was found within these groups.

CONCLUSIONS

The results of serological tests pointed to an association between the actions taken against Triatoma infestans and the decline and eventual control of the transmission of Chagas disease in the late 1960s.

[Hepatic dysfunction in myoglobinuric acute renal failure (rhabdomyolysis)--experimental study in rats]

Liver damage as a consequence of rhabdomyolysis (RM) has not been well established on clinical and experimental grounds. Hepatic dysfunction was then investigated in rats 24 h after induction of acute renal failure with glycerol. Forty male Wistar rats (220-270 g) were dehydrated for 24 h and were divided in two group: GI experimental group (n = 14)-50% glycerol was injected (10 ml/Kg, one-half of the dose in each hindlimb muscle) and GII control group (n = 26)-animals received injection of saline solution. Twenty-four hours after the glycerol or saline injection all the animals were killed. Serum urea, creatinine, transaminases (AST, ALT) and CK were measured and significantly high values were obtained in experimental animals. Arterial blood pressure was measured and remained within normal levels in both groups. Hepatocyte mitochondrial respiratory function was estimated polarographically with determination of oxygen consumption without ADP (Basal respiration-State 4) and in the presence of ADP (Activated respiration-State 3). In experimental group (GI) there was significant low values of oxygen consumption in state 3, decrease of respiratory control rate and in ADP/O ratio (p < 0.05). Histological studies of the liver revealed a periportal necrosis and centrilobular degeneration. These studies suggested that hepatic dysfunction is an additional complication of glycerol-induced rhabdomyolysis. The pathogenesis and clinical implications of these abnormalities are discussed.

[Incidence of dyslipidemia and its relation to coronary artery disease in Brazilian populations]

PURPOSE

To describe the incidence of dyslipidemia and its relation to coronary artery disease (CAD) in two brazilian populations.

PATIENTS AND METHODS

1.261 subjects were analyzed; 674, whose mean age was 53 years, came from a cardiology private office (population A) and 587, whose mean age was 37 years, were employees of an engineering company (population B). Cholesterol was determined by the enzymatic method Chod-pap and LDL calculated by the Friedwald's formula.

RESULTS

CAD was present in 35.1% of population A and in 1.4% of population B. In population A total cholesterol and LDL were above the expected, in all age groups. About 70% of these patients had cholesterol greater than 200 mg% and LDL greater than 130 mg%, which are considered desirable levels; 28% of women and 44% of men had HDL less than 35 mg%. Conversely, in population B total cholesterol and LDL were slightly above normal only in patients greater than 45 years old. In addition, about 65% of population had cholesterol less than 200 mg% and LDL less than 130 mg%; even so, 28% of women and 48% of men had HDL less than 35 mg%. In population A, there were no significant differences between the percentages of patients with and without CAD, over a wide range of cholesterol values. Similarly, levels of LDL, HDL and triglycerides as well as the incidence of hypertension, smoking and diabetes did not differ between patients with and without CAD.

CONCLUSION

There is a high incidence of dyslipidemia in these brazilian populations, especially among patients from private office. Further, the isolated measurement of lipid fractions does not discriminate between patients with and without DAC, suggesting that other factors are involved in the genesis of the disease.

Induction of autolysis in Streptococcus faecium

Autolysis of exponential-phase Streptococcus faecium cells was promoted by pretreating the bacteria (freezing-thawing; -70 degrees C) in Tris buffer, followed by incubation at 37 degrees C in the same buffer. The effect was dependent on Tris concentration. The pretreatment provoked ultrastructurally visible damage with extensive loss of K+ and leakage of UV-absorbing components. No autolysis was observed when the bacteria frozen-thawed in Tris were incubated in the presence of the autolysin inhibitor N-bromosuccinimide nor when they had been grown in the presence of chloramphenicol or tetracycline. Furthermore, two autolytic-defective mutants, EC31 and EC78, isolated from S. faecium, did not autolyse when frozen-thawed and incubated in Tris. Freezing-thawing in Tris, however, imparted extensive cell damage to the mutants and to the antibiotic-treated bacteria as well as considerable leakage of K+ and UV-absorbing materials. These observations indicate that the lysis of S. faecium reported above is due to the activity of the endogenous bacterial autolysin. Induction of autolysis of S. faecium by freezing-thawing was also observed, although to a lesser extent, when Tris was replaced by imidazole.

A turbidimetric and electron microscopic study of the effects of several parameters on the lysis of Streptococcus faecalis by lysozyme

The lytic effect of lysozyme on Streptococcus faecalis ATCC 9790 was studied by spectrophotometry and electron microscopy and it was found to be highly dependent on the ionic strength of the suspending media and on the ratio lysozyme to bacterial cell mass. When 7.2 X 10(8) bacteria/mL are exposed to 0.4 mg/mL of lysozyme in media with low ionic strength, the enzyme is bound in great amounts, as deduced from protein determinations and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS--PAGE); the binding prevents bacteriolysis in spite of the removal of the cell wall. Extensive lysis of S. faecalis could be obtained by reducing the ratio of lysozyme to bacterial cell mass. Stabilization of S. faecalis by lysozyme was also observed when exponential phase cells incubated under conditions that promote spontaneous autolysis (incubation in 0.05 M tris(hydroxymethyl)aminomethane buffer, pH 8.0, ionic strength = 0.01675) do not lyse and do not leak material which absorbs at 260 nm when lysozyme was present at the highest concentration.