Alonso-García María, Suárez-Vega Aroa, Fonseca Pablo A S, Marina Héctor, Pelayo Rocío, Mateo Javier, Arranz Juan-José, Gutiérrez-Gil Beatriz
Departemento de Producción Animal, Facultad de Veterinaria, Universidad de León, León, Spain.
Departamento de Higiene y Tecnología de los Alimentos, Facultad de Veterinaria, Universidad de León, León, Spain.
Front Vet Sci. 2023 May 15;10:1150996. doi: 10.3389/fvets.2023.1150996. eCollection 2023.
Suckling lamb meat is highly appreciated in European Mediterranean countries because of its mild flavor and soft texture. In suckling lamb carcasses, perirenal and pelvic fat depots account for a large fraction of carcass fat accumulation, and their proportions are used as an indicator of carcass quality.
This study aimed to characterize the genetic mechanisms that regulate fat deposition in suckling lambs by evaluating the transcriptomic differences between Spanish Assaf lambs with significantly different proportions of kidney knob and channel fat (KKCF) depots in their carcasses (4 High-KKCF lambs vs. 4 Low-KKCF lambs).
The analyzed fat tissue showed overall dominant expression of white adipose tissue gene markers, although due to the young age of the animals (17-36 days), the expression of some brown adipose tissue gene markers (e.g., , ) was still identified. The transcriptomic comparison between the High-KKCF and Low-KKCF groups revealed a total of 80 differentially expressed genes (DEGs). The enrichment analysis of the 49 DEGs with increased expression levels in the Low-KKCF lambs identified significant terms linked to the biosynthesis of lipids and thermogenesis, which may be related to the higher expression of the gene in this group. In contrast, the enrichment analysis of the 31 DEGs with increased expression in the High-KKCF lambs highlighted angiogenesis as a key biological process supported by the higher expression of some genes, such as and , which encode a major angiogenic factor and a large adhesive extracellular matrix glycoprotein, respectively.
The increased expression of sestrins, which are negative regulators of the mTOR complex, suggests that the preadipocyte differentiation stage is being inhibited in the High-KKCF group in favor of adipose tissue expansion, in which vasculogenesis is an essential process. All of these results suggest that the fat depots of the High-KKCF animals are in a later stage of development than those of the Low-KKCF lambs. Further genomic studies based on larger sample sizes and complementary analyses, such as the identification of polymorphisms in the DEGs, should be designed to confirm these results and achieve a deeper understanding of the genetic mechanisms underlying fat deposition in suckling lambs.
哺乳期羔羊的肉因其温和的风味和柔软的质地而在欧洲地中海国家备受青睐。在哺乳期羔羊胴体中，肾周和盆腔脂肪库占胴体脂肪积累的很大一部分，其比例被用作胴体品质的指标。
本研究旨在通过评估西班牙阿萨夫羔羊胴体中肾脂囊和通道脂肪（KKCF）比例差异显著的羔羊（4只高KKCF羔羊与4只低KKCF羔羊）之间的转录组差异，来表征调节哺乳期羔羊脂肪沉积的遗传机制。
分析的脂肪组织总体上显示白色脂肪组织基因标记物占主导表达，尽管由于动物年龄较小（17 - 36天），仍可识别出一些棕色脂肪组织基因标记物（如 ， ）的表达。高KKCF组和低KKCF组之间的转录组比较共揭示了80个差异表达基因（DEG）。对低KKCF羔羊中表达水平升高的49个DEG进行的富集分析确定了与脂质生物合成和产热相关的重要术语，这可能与该组中 基因的较高表达有关。相比之下，对高KKCF羔羊中表达升高的31个DEG进行的富集分析突出了血管生成是一个关键的生物学过程，这由一些基因的较高表达所支持，例如 和 ，它们分别编码一种主要的血管生成因子和一种大型粘附细胞外基质糖蛋白。
作为mTOR复合物负调节因子的 sestrins表达增加，表明高KKCF组中前脂肪细胞分化阶段受到抑制，有利于脂肪组织扩张，其中血管生成是一个重要过程。所有这些结果表明，高KKCF动物的脂肪库比低KKCF羔羊的脂肪库处于发育的后期阶段。应设计基于更大样本量的进一步基因组研究以及互补分析，如鉴定DEG中的多态性，以证实这些结果并更深入地了解哺乳期羔羊脂肪沉积的遗传机制。
