Detection of quantitative trait loci for mineral content of Nelore longissimus dorsi muscle.

BACKGROUND: Beef cattle require dietary minerals for optimal health, production and reproduction. Concentrations of minerals in tissues are at least partly genetically determined. Mapping genomic regions that affect the mineral content of bovine longissimus dorsi muscle can contribute to the identification of genes that control mineral balance, transportation, absorption and excretion and that could be associated to metabolic disorders. METHODS: We applied a genome-wide association strategy and genotyped 373 Nelore steers from 34 half-sib families with the Illumina BovineHD BeadChip. Genome-wide association analysis was performed for mineral content of longissimus dorsi muscle using a Bayesian approach implemented in the GenSel software. RESULTS: Muscle mineral content in Bos indicus cattle was moderately heritable, with estimates ranging from 0.29 to 0.36. Our results suggest that variation in mineral content is influenced by numerous small-effect QTL (quantitative trait loci) but a large-effect QTL that explained 6.5% of the additive genetic variance in iron content was detected at 72 Mb on bovine chromosome 12. Most of the candidate genes present in the QTL regions for mineral content were involved in signal transduction, signaling pathways via integral (also called intrinsic) membrane proteins, transcription regulation or metal ion binding. CONCLUSIONS: This study identified QTL and candidate genes that affect the mineral content of skeletal muscle. Our findings provide the first step towards understanding the molecular basis of mineral balance in bovine muscle and can also serve as a basis for the study of mineral balance in other organisms.

Magnetic solid phase extraction as a nonchromatographic method for the quantification of ultratrace inorganic arsenic in rice by inductively coupled plasma-optical emission spectrometry (ICP OES).

An alternative analytical method was developed for the quantification of inorganic arsenic (iAs) in rice by ICP OES. Iron nanoparticles modified with an organophosphorus compound were used as the solid phase for MSPE of iAs from the plant matrix. The MSPE procedure was performed using 4 mL of a buffer solution with pH 4.0, 20 mg of the nanomaterial, and a 15-min extraction time. The total As (tAs) by ICP OES was also quantified using the same MSPE procedure after solubilization of the samples by a block digester. The accuracy of tAs and iAs quantification was verified using CRM NIST 1568b (97 % and 101 % recovery, respectively). The precision (RSD < 15 %) and LOD and LOQ (1.08 and 3.70 µg kg-1, respectively) of the proposed method were satisfactory. The rice samples had tAs contents between 0.090 and 0.295 mg kg-1 and iAs mass fractions between 0.055 and 0.109 mg kg-1.

Application of QuEChERS method and gas chromatography-mass spectrometry for the analysis of cypermethrin residue in milk.

Analytical methods for the isolation and determination of cypermethrin in milk, based on the solid-phase microextraction (SPME) and QuEChERS methods (Quick, Easy, Cheap, Effective, Rugged, and Safe) are presented. The SPME technique was not appropriate to analyse cypermethrin in milk, even establishing the best extraction conditions, polydimethylsiloxane fiber, 60 min time extraction, 60 °C temperature extraction, addition of salt (NaCl) and stirring rate. The extraction efficiency was low probably because of the matrix constituents. The QuEChERS method involves the extraction of the analyte with acetonitrile and simultaneous liquid-liquid partitioning formed by adding anhydrous MgSO(4) plus NaCl, followed by the removal of residual water and cleanup using a procedure called dispersive solid-phase extraction, in which anhydrous MgSO(4) plus PSA and C18 are mixed with 1 mL of acetonitrile extract. The detection and quantification limits were 0.01 and 0.04 mg kg(-1), respectively, and the percentage recovery obtained ranged from 92 to 105% with relative standard deviations below 7%.

Non-chromatographic arsenic speciation analyses in wild shrimp (Farfantepenaeus brasiliensis) using functionalized magnetic iron-nanoparticles.

A new iron-magnetic nanomaterial functionalized with organophosphorus compound was used as solid-phase for arsenic speciation analysis in seafood samples by ICP-MS. The procedure was optimized using chemometric tools and the variables pH = 4.0, 15 min extraction time, and 20 mg of mass of material were obtained as the optimum point. The inorganic arsenic (iAs) extracted using nanoparticles presented concentrations between 20 and 100 µg kg-1 in the evaluated samples. The method was validated for accuracy using CRMs DOLT-5 and DORM-4. It was possible to reuse the same magnetic nanomaterial for 6 successive cycles, and we obtained a detection limit of 16.4 ng kg-1. The proposed method is suitable for the use of inorganic speciation of As, presenting good accuracy, precision, relatively low cost, and acquittance to green chemistry principles.

Bioaccumulation and acute toxicity of As(III) and As(V) in Nile tilapia (Oreochromis niloticus).

The distribution of arsenic in the different tissues of tilapia fish is determined by the exposure time and the depuration rate. The mechanisms of toxicity/carcinogenicity depend on the arsenic species involved in the biotransformation processes. After a 7-day exposure period, the accumulation of inorganic arsenic (iAs) in the tilapia tissues studied was in the order: liver > stomach > gills > muscles. In bioaccumulation assays, the values of the organ uptake constant (ka) ranged from 0.06 to 0.51 mL g-1 d-1, while the depuration rate constant (kd) values were in the range 0.03-1.15 d-1. Higher iAs bioaccumulation factor (BCF) values were observed for the stomach (3.1 mL g-1) and the liver (1.6 mL g-1), reflecting their high capacity to accumulate iAs species. These organs act as long-term storage sites for iAs, following chronic exposure. The LC50 values were determined considering the average iAs concentration and the cumulative fish mortality. For As(III), the LC50 values indicated fish mortality at concentrations above 30 mg L-1. The fish showed greater tolerance to exposure to As(V), compared to As(III), with fish mortality after the second day of exposure requiring an As(V) concentration 7-fold higher than As(III).

Flow injection potentiometric system for the simultaneous determination of inositol phosphates and phosphate: phosphorus nutritional evaluation on seeds and grains.

A simple flow injection potentiometric (FIP) system, which uses a tubular cobalt electrode, has been developed for phosphorus nutritional evaluation of seeds and grains. Inorganic phosphorus, P(i), is determined using a 1 x 10(-2) mol.L(-1) potassium phthalate buffer solution adjusted at pH 4. A sensitivity of 47 mV/decade and an operating range from 10 to 1000 mg.L(-1) (1 x 10(-4)-1 x 10(-2) M) of dihydrogen phosphate are obtained. The inositol phosphates amount, which is referred to the organic phosphorus, P(org), is directly determined from extracts using a 1 x 10(-2) mol.L(-1) Tris-HCl buffer solution adjusted at pH 8. A sensitivity of 127 mV/decade and an operating range of 10-1000 mg.L(-1) (2.5 x 10(-4)-5 x 10(-3) M) of P(org) (expressed as inositol hexakisphosphoric acid monocalcium) are achieved. Some samples of seed and grain are analyzed by an ICP-OES and a spectrophotometric method to compare results to the developed flow system; no significant differences at the 95% confidence level are observed using a paired t test. Other samples such as animal nursing feed, soybean meal, and corn are also analyzed with the proposed FIP system, showing a good correlation to the ICP-OES values.

Sample preparation for arsenic speciation in terrestrial plants--a review.

Arsenic is an element widely present in nature. Additionally, it may be found as different species in several matrices and therefore it is one of the target elements in chemical speciation. Although the number of studies in terrestrial plants is low, compared to matrices such as fish or urine, this number is raising due to the fact that this type of matrix are closely related to the human food chain. In speciation analysis, sample preparation is a critical step and several extraction procedures present drawbacks. In this review, papers dealing with extraction procedures, analytical methods, and studies of species conservation in plants cultivated in terrestrial environment are critically discussed. Analytical procedures based on extractions using water or diluted acid solutions associated with HPLC-ICP-MS are good alternatives, owing to their versatility and sensitivity, even though less expensive strategies are shown as feasible choices.