RESUMO
The aim of this study was to identify mRNA isoforms and small genetic variants that may be affecting marbling and beef color in Nellore cattle. Longissimus thoracis muscle samples from 20 bulls with different phenotypes (out of 80 bulls set) for marbling (moderate (n = 10) and low (n = 10) groups) and beef color (desirable (n = 10) and undesirable (n = 9) group) traits were used to perform transcriptomic analysis using RNA sequencing. Fourteen and 15 mRNA isoforms were detected as differentially expressed (DE) (P-value ≤ 0.001) between divergent groups for marbling and meat color traits, respectively. Some of those DE mRNA isoforms have shown sites of splicing modified by small structural variants as single nucleotide variant (SNV), insertion, and/or deletion. Enrichment analysis identified metabolic pathways, such as O2/CO2 exchange in erythrocytes, tyrosine biosynthesis, and phenylalanine degradation. The results obtained suggest potential key regulatory genes associated with these economically important traits for the beef industry and for the consumer.
Assuntos
Carne , Isoformas de RNA , Animais , Bovinos/genética , Variação Genética , Masculino , Carne/análise , Músculo Esquelético/metabolismo , Fenótipo , Isoformas de RNA/análise , Isoformas de RNA/metabolismo , Análise de Sequência de RNARESUMO
Bovine skeletal muscle growth characteristics and muscle fiber type frequency are of primary interest because they both play a fundamental role in modeling meat quality and tenderness, although the precise relationship remains undefined. Growth promoters like rbST have been reported to have varying effects on muscle growth performance. The objective of this experiment was to evaluate the histochemistry and growth characteristics of bovine semitendinosus muscle treated with rbST. Animals were divided into two groups: control (saline-injected; n=8) and rbST-injected (15 ug/kg; n=8). Heifers were injected every 14 days from day 210 until day 285 of age. Muscle samples were collected (day 210 and 360) and frozen in liquid nitrogen. Histological sections (10 um) underwent morphological and histochemical analysis (HE, NADH-TR and mATPase), morphometry (fiber area and distribution), and biochemical analysis. Fibers were classified as SO, FOG, and FG. FOG fiber percentage distribution decreased and cross-sectional area increased in rbSTtreated animals. Recombinant bST caused a greater animal body weight gain and FOG fiber hypertrophy, while contributing to a decrease in FOG fiber distribution. We conclude that the phenotypic modulation seen in this muscle fiber suggests a potential role of this muscle in modeling the meat quality.