Single-base editing in IGF2 improves meat production and intramuscular fat deposition in Liang Guang Small Spotted pigs

Background Chinese indigenous pigs are popular with consumers for their juiciness,flavour and meat quality,but they have lower meat production.Insulin-like growth factor 2(IGF2) is a maternally imprinted growth factor that promotes skeletal muscle growth by regulating cell proliferation and differentiation.A single nucleotide polymorphism(SNP) within intron 3 of porcine IGF2 disrupts a binding site for the repressor,zinc finger BED-type containing 6(ZBED6),leading to up-regulation of IGF2 and causing major effects on muscle growth,heart size,and backfat thickness.This favorable mutation is common in Western commercial pig populations,but absent in most Chinese indigenous pig breeds.To improve meat production of Chinese indigenous pigs,we used cytosine base editor 3(CBE3)to introduce IGF2 intron3-C3071T mutation into porcine embryonic fibroblasts(PEFs) isolated from a male Liang Guang Small Spotted pig(LGSS),and single-cell clones harboring the desired mutation were selected for somatic cell nuclear transfer(SCNT) to generate the founder line of IGF2^(T/T) pigs.Results We found the heterozygous progeny IGF2^(C/T) pigs exhibited enhanced expression of IGF2,increased lean meat by 18%-36%,enlarged loin muscle area by 3%-17%,improved intramuscular fat(IMF) content by 18%-39%,marbling score by 0.75-1,meat color score by 0.53-1.25,and reduced backfat thickness by 5%-16%.The enhanced accumulation of intramuscular fat in IGF2^(C/T) pigs was identified to be regulated by the PI3K-AKT/AMPK pathway,which activated SREBP1 to promote adipogenesis.Conclusions We demonstrated the introduction of IGF2-intron3-C3071T in Chinese LGSS can improve both meat production and quality,and first identified the regulation of IMF deposition by IGF2 through SREBP1 via the PI3KAKT/AMPK signaling pathways.Our study provides a further understanding of the biological functions of IGF2and an example for improving porcine economic traits through precise base editing.

Characteristics of Deposition of Inosine Monophosphate(IMP) and Intramuscular Fat(IMF) in Muscles of Jinghai Yellow Chicken and Its Crossbreeds

[Objective] This study aimed to investigate the characteristics of deposition of inosine monophosphate （IMP） and intramuscular fat （IMF） in muscles of Jinghai yellow chickens and its crossbred.[Method] The characteristics of IMP and IMF deposition of 112-day-old Jinghai yellow chickens （J×J） and its two different 70-day- old crossbreeds （J×B and B×B） were analyzed. The IMP content in breast muscle and leg muscle were determined by HPLC. [Result] The contents of IMP and cor- rected inosine monophosphate （IMPc） in breast muscle were significantly or ex- tremely significantly higher than that in leg muscle of the chickens in the three groups whether in male or female chickens （P〈0.05 or P〈0.01）. There were no sig- nificant difference in the contents of IMP and IMPc between hens and roosters （P〉 0.05）. The fresh degree of breast muscle and leg muscle was 96,11%-98.16% and 87.22%-93.07%, respectively. And the fresh degree of breast muscle was higher than that of leg muscle. In the three groups, the IMF content in leg muscle was significantly higher than that in breast muscle whether in male or female chickens （P〈0.05）. The contents of IMF in breast muscle and leg muscle were 0.36%-0.75% and 1.84%-2.38%, respectively. The iMP content in breast muscle of chickens in Bx J group was extremely significantly higher than that in breast muscle of chickens in JxJ group （P〈0.01）, but the contents of IMPc and iMF of breast muscle and leg muscle of the chickens in the three groups had no significant difference （P〉0.05）. [Conclusion] To sum up, the freshness and flavor significantly differ between the breast muscle and leg muscle of chickens, but show no significant difference among the three groups.

Lysine 2-hydroxyisobutyrylation levels determined adipogenesis and fat accumulation in adipose tissue in pigs

Background Excessive backfat deposition lowering carcass grade is a major concern in the pig industry,especially in most breeds of obese type pigs.The mechanisms involved in adipogenesis and fat accumulation in pigs remain unclear.Lysine 2-hydroxyisobutyrylation(Khib),is a novel protein post-translational modification(PTM),which play an important role in transcription,energy metabolism and metastasis of cancer cells,but its role in adipogenesis and fat accumulation has not been shown.Results In this study,we first analyzed the modification levels of acetylation(Kac),Khib,crotonylation(Kcr)and succinylation(Ksu)of fibro-adipogenic progenitors(FAPs),myogenic precursors(Myo)and mesenchymal stem cells(MSCs)with varied differentiation potential,and found that only Khib modification in FAPs was significantly higher than that in MSCs.Consistently,in parallel with its regulatory enzymes lysine acetyltransferase 5(KAT5)and histone deacetylase 2(HDAC2)protein levels,the Khib levels increased quadratically(P<0.01)during adipogenic differentiation of FAPs.KAT5 knockdown in FAPs inhibited adipogenic differentiation,while HDAC2 knockdown enhanced adipogenic differentiation.We also demonstrated that Khib modification favored to adipogenic differentiation and fat accumulation by comparing Khib levels in FAPs and backfat tissues both derived from obese-type pigs(Laiwu pigs)and lean-type pigs(Duroc pigs),respectively.Accordingly,the expression patterns of KAT5 and HDAC2 matched well to the degree of backfat accumulation in obese-and lean-type pigs.Conclusions From the perspective of protein translational modification,we are the first to reveal the role of Khib in adipogenesis and fat deposition in pigs,and provided new clues for the improvement of fat accumulation and distribution as expected via genetic selection and nutritional strategy in obese-type pigs.

Developmental Changes of the FAS and HSL mRNA Expression and Their Effects on the Content of Intramuscular Fat in Kazak and Xinjiang Sheep

Twenty-four male Kazak sheep and 30 Xinjiang fine wool sheep at different ages were selected to investigate the development-dependent expression levels of fatty acid synthase （FAS） gene and hormone-sensitive lipase （HSL） gene in muscle and their effects on the contents of intramuscular fat （IMF）. Longissimus dorsal muscle was sampled to measure IMF and total RNA was extracted to determine FAS and HSL mRNA expression levels by real-time PCR. The results showed that： l） The IMF content increased continuously with growth and showed significant differences （P 〈 0.05） between different age groups in male Kazak sheep, but in Xinjiang fine wool sheep there was no such difference observed. Furthermore, the IMF contents in Kazak were much higher （P 〈 0.01） than that of the other breed from day 30 to 90. 2） FAS mRNA expression level was the highest （P 〈 0.05） on day 0 in Kazak sheep and then declined with growth, in the other breed the gene showed a d‘ecline-rise-decline-rise＇ expression manner as the animals grew. HSL mRNA expression level had a similar model in two breeds, in Kazak sheep it was the highest on day 0 （P 〈 0.05） and in Xinjiang fine wool sheep on day 30 （P 〈 0.01）, then both decreased after this term. 3） In male Kazak sheep, FAS and HSL mRNA expression level were both negatively related to IMF content （r= -0.485 （P = 0.02）, r= -0.423 （P = 0.05））, and the ratio of FAS/HSL expression exhibited significantly negatively related IMF contents. In male Xinjiang sheep, there were no obvious relationship between FAS and HSL expression and IMF content （P 〉 0.05）.

Linoleic acid metabolic pathway allows for an efficient increase of intramuscular fat content in pigs

Background: Intramuscular fat(IMF) content is a relevant trait for high-quality meat products such as dry-cured ham,but increasing IMF has the undesirable correlated effect of decreasing lean growth.Thus,there is a need to find selection criteria for IMF independent from lean growth.In pigs,the proportion of linoleic(C18:2) and arachidonic(C20:4) acids decline with fat deposition and therefore they can be considered as indicators of fatness.The aim of this research was to estimate the genetic variation for C18:2 and C20:4 in IMF and their genetic correlations with IMF and lean growth traits,with the objective to assess their potential as specific biomarkers of IMF.The analysis was conducted using a full-pedigreed Duroc resource line with 91,448 records of body weight and backfat thickness(BT) at 180 days of age and 1371 records of fatty acid composition in the muscle gluteus medius.Results: The heritability estimates for C18:2 and C20:4 in IMF,whether expressed in absolute(mg/g of muscle) or in relative(mg/g of fatty acid) terms,as well as for their ratio(C20:4/C18:2),were high(> 0.40),revealing that the C18:2 to C20:4 pathway is subjected to substantial genetic influence.Litter effects were not negligible,with values ranging from8% to 15% of the phenotypic variance.The genetic correlations of C18:2 and C20:4 with IMF and BT were negative(-0.75 to-0.66,for IMF,and-0.64 to-0.36,for BT),if expressed in relative values,but almost null(-0.04 to 0.07),if expressed in absolute values,except for C18:2 with IMF,which was highly positive(0.88).The ratio of C20:4 to C18:2 also displayed a stronger genetic correlation with IMF(-0.59) than with BT(-0.10).Conclusions: The amount of C18:2 in muscle can be used as an IMF-specific biomarker.Selection for the absolute amount of C18:2 is expected to deliver a similar response outcome as selection for IMF at restrained BT.Further genetic analysis of the C18:2 metabolic pathway may provide new insights into differential fat deposition among adipose tissues and on candidate genes for molecular markers targeting specifically for one of them.

Changes of Intramuscular Fat Composition,Lipid Oxidation and Lipase Activity in Biceps femoris and Semimembranosus of Xuanwei Ham During Controlled Salting Stages

Fatty acid composition of neutral lipids （NLs）, phospholipids （PLs） and free fatty acids （FFAs） from intramuscular fat （IMF）, lipid oxidation and lipase activity in muscle Semimembranosus （SM） and msucle Biceps femoris （BF） of dry-cured Xuanwei ham during the 90-d salting stages were analysed. The salt content increased from 0.34 to 3.52%in BF and from 0.10 to 5.42%in SM during the 90 d salting stage, respectively. PLs of IMF in both BF and SM decreased 54.70%（P〈0.001） and 34.64%（P〈0.05）, furthermore, the saturated fatty acids （SFA）, monounsaturated fatty acids （MUFA） and polyunsaturated fatty acids （PUFA） of PLs in both muscles were hydrolysed almost isochronously. FFAs were increased from 0.46 g 100 g-1 lipids to 2.92 g 100 g-1 lipids in BF at the end of salting, which was lower than SM （from 1.29 g 100 g-1 lipids to 9.70 g 100 g-1 lipids）. The activities of acid lipase, neutral lipase and acid phospholipase all remained active in the 90 d. The thiobarbituric acid reactive substances （TBARS） was slowly increased to 1.34 mg kg-1 muscle in BF and to 2.44 mg kg-1 muscle in SM during the salting stage. In conclusion, the controlled salting process prompted the hydrolysis of PLs of IMF notably and increased the lipid oxidation of muscles within some limits.

A Review of Factors Influencing Intramuscular Fat Content in Porcine Meat

Intramuscular fat （IMF）, an important flavor precursor of porcine meat, is closely related to pork quality traits such as pH, color, tenderness, water-holding capacity （WHC） and juiciness, and thus is one of the important factors affecting pork quality. Pork IMF content is not only associated with swine breed on heredity, but also influenced by the alteration of nutrients in diet. These may give a possibility for researchers to improve the IMF content and pork quality by their work on swine breed or heredity, and nutrition regulation in diet. Therefore, this article summarizes the effects of swine breed and nutrition regulation on IMF content briefly to provide some information for future researches.

A selected population study reveals the biochemical mechanism of intramuscular fat deposition in chicken meat

Background:Increasing intramuscular fat(IMF)is an important strategy to improve meat quality,but the regulation mechanism of IMF deposition needs to be systematically clarified.Results:A total of 520 chickens from a selected line with improved IMF content and a control line were used to investigate the biochemical mechanism of IMF deposition in chickens.The results showed that the increased IMF would improve the flavor and tenderness quality of chicken meat.IMF content was mainly determined both by measuring triglyceride(TG)and phospholipid(PLIP)in muscle tissue,but only TG content was found to be decisive for IMF deposition.Furthermore,the increase in major fatty acid(FA)components in IMF is mainly derived from TGs(including C16:0,C16:1,C18:1n9c,and C18:2n6c,etc.),and the inhibition of certain very-long-chain FAs would help to IMF/TG deposition.Conclusions:Our study elucidated the underlying biochemical mechanism of IMF deposition in chicken:Prevalent accumulation of long-chain FAs and inhibitions of medium-chain FAs and very long chain FA would jointly result in the increase of TGs with the FA biosynthesis and cellular uptake ways.Our findings will guide the production of high-quality chicken meat.

The relationship between body mass index, thickness of subcutaneous fat, and the gluteus muscle as the intramuscular injection site

An intramuscular injection (IMI) is an injection given directly into the central area of a specific muscle. Certain medicines need to be administered by the gluteal route for these to be effective. The aim of this study was to determine the influence of body mass index (BMI), subcutaneous fat, and muscular thickness of the dorsogluteal IMI site among healthy Japanese women. There were 39 healthy female subjects who volunteered and met the criteria. Their ages ranged from 40s to 60s (50.82 ± 6.04). With the data collected using the B-mode ultrasound images of the dorsogluteal site, it was found that the distance from the epidermis to the under-fascia (DEUF) of the gluteus maximus was dissimilar between the subject’s right and left buttocks. It was found that the distance from the epidermis to the iliac bone (DEI) was significantly more on the right than on the left buttocks. In the case of an adult Japanese woman with a BMI of 21 or more, the DEUF of the gluteus medius was found to be about 30 mm, and the DEI was approximately 50 mm or more. Based on these findings, it is recommended that a needle length of 38 mm (1.5 inches) can be safely used to administer IMIs to the gluteus medius muscle to effectively and efficiently deliver medications through the IMI route.

In vivo prediction of intramuscular fat in pigs using computed tomography

One hundred and four pure-bred Norwegian Duroc boars were CT (computed tomography) scanned to predict the in vivo intramuscular fat percentage in the loin. The animals were slaughtered and the loin was cut commercially. A muscle sample of the m. Longissimus dorsi was sampled and analyzed by the use of near-infrared spectroscopy. Data from CT images were collected using an in-house MATLAB script. Calibration models were made using PLS (partial least square) regression, containing independent data from CT images and dependent data from near-infrared spectroscopy. The data set used for calibration was a subset of 72 animals. The calibration models were validated using a subset of 32 animals. Scaling of independent data and filtering using median filtering were tested to improve predictions. The results showed that CT is not a feasible method for in vivo prediction of intramuscular content in swine.

Dietary calcium supplementation promotes the accumulation of intramuscular fat

Background:In the livestock industry,intramuscular fat content is a key factor affecting meat quality.Many studies have shown that dietary calcium supplementation is closely related to lipid metabolism.However,few studies have examined the relationship between dietary calcium supplementation and intramuscular fat accumulation.Methods:Here,we used C2C12 cells,C57BL/6 mice(n=8)and three-way cross-breeding pigs(Duroc×Landrace×Large white)(n=10)to study the effect of calcium addition on intramuscular fat accumulation.In vitro,we used calcium chloride to adjust the calcium levels in the medium(2 mmol/L or 3 mmol/L).Then we measured various indicators.In vivo,calcium carbonate was used to regulate calcium levels in feeds(Mice:0.5%calcium or 1.2%calcium)(Pigs:0.9%calcium or 1.5%calcium).Then we tested the mice gastrocnemius muscle triglyceride content,pig longissimus dorsi muscle meat quality and lipidomics.Results:In vitro,calcium addition(3 mmol/L)had no significant effect on cell proliferation,but promoted the differentiation of C2C12 cells into slow-twitch fibers.Calcium supplementation increased triglyceride accumulation in C2C12 cells.Calcium addition increased the number of mitochondria and also increased the calcium level in the mitochondria and reduced the of key enzymes activity involved inβ-oxidation such as acyl-coenzyme A dehydrogenase.Decreasing mitochondrial calcium level can alleviate lipid accumulation induced by calcium addition.In addition,calcium addition also reduced the glycolytic capacity and glycolytic conversion rate of C2C12 cells.In vivo,dietary calcium supplementation(1.2%)promoted the accumulation of triglycerides in the gastrocnemius muscle of mice.Dietary calcium supplementation(1.5%)had no effect on pig weight,but significantly improved the flesh color of the longissimus dorsi muscle,reduced the backfat thickness and increased intramuscular fat content in pigs.Besides,calcium addition had no effect on longissimus dorsi pH,electrical conductivity and shear force.Conclusions:These results suggest that calcium addition promotes intramuscular fat accumulation by inhibiting the oxidation of fatty acids.These findings provide a new tool for increasing intramuscular fat content and an economical strategy for improving meat quality.

调控肉牛肌内脂肪沉积的分子机制研究进展

肉牛肌内脂肪(intramuscular fat,IMF)是指存在于肌纤维内的脂肪组织,含量与牛肉的多汁性、嫩度和适口性呈正相关关系,是决定牛肉质量等级的重要因素之一。明确肉牛IMF沉积的产生和调控机制是提高牛肉IMF含量的有效途径。文章对肉牛IMF沉积过程及调控IMF沉积的候选基因、转录因子和非编码RNA(non-coding RNA,ncRNA)进行综述,旨在为进一步解析肉牛IMF沉积的分子机制和推动肉牛肉质性状选育进程提供参考。

影响肉牛肌内脂肪沉积的主要通路

决定大理石花纹水平的肌内脂肪含量被认为是影响牛肉嫩度、多汁性、风味和颜色等感官质量的重要因素之一。脂肪细胞的成熟须经历细胞增殖和细胞分化两个阶段。在此过程中,一些促进因子(包括PPARγ、IGF-l等)以及抑制因子(包括糖蛋白、转化生长因子β等)协同作用,通过不同通路影响肌内脂肪沉积。本文分析了脂肪生成的转录调控,阐述了信号通路在脂肪生成中的作用,以期为相关研究人员提高牛肉大理石花纹水平提供参考。

动物肌内脂肪沉积的影响因素及其分子机制

肌内脂肪(IMF)指在肌肉内、肌纤维间所沉积的脂肪,其含量与肌肉的多汁度、剪切力、嫩度以及肉质显著正相关,因此合理的IMF含量将有助于改善肉品的质量和提高其风味。IMF生成的过程涉及复杂且高度协调的基因表达调控程序,受多种因素影响。因此,本文综述了影响动物IMF沉积的转录因子、关键代谢酶、信号通路以及非编码RNA。研究显示,转录因子在调节脂肪细胞分化和脂肪合成的过程中起着重要作用;酶催化反应则介导了脂肪生成和降解的关键步骤;此外,通过调控特定信号通路和非编码RNA的表达,也能够对IMF沉积进行调控。深入了解和运用这些分子机制对于肉制品质量的提升和生产优质肉制品具有重要意义。本综述为进一步研究和运用这些分子机制提供了参考依据,以期改善肉制品的质量,满足消费者对优质肉制品的需求。

黄羽肉鸡IMF选择与遗传参数估计

利用家系选择的方法，对黄羽肉鸡90日龄胸肌肌内脂肪含量（IMF）进行了4个世代的选择；采用动物模型（样本数N=632～1084）和MTDFREML软件对部分肉质性状进行了遗传力（h^2）和遗传相关（r）估计。试验结果表明：经过4个世代的选择，G4代比G0代IMF含量提高了17．8％（P〈0．01），变异系数由29．59％降低到21．72％。胸肌IMF含量的估计遗传力h^2=0．220，4个世代的平均实现遗传力h^2=0．322，初步说明IMF含量为中等遗传力性状，可以通过选择提高。腹脂重、腹脂率、脂带宽、皮脂厚、冠高、冠厚、90日龄体重等性状的遗传力在0．08～0．54范围内，胸肌IMF、腿肌IMF与腹脂重等性状间呈遗传正相关。

去势对武定鸡胸肌组织脂质组成的影响

为揭示去势对鸡胸肌组织脂质组成的影响,试验采用索氏提取法和UHPLC/Q-TOF-MS检测技术对去势组和假手术组武定鸡肌肉组织进行肌内脂肪(IMF)含量测定和非靶向脂质组学研究。结果显示:去势组武定鸡胸肌组织IMF含量显著高于假手术组(P<0.05);脂质组学检测到21种脂质亚类和553个脂质分子,其中去势组胸肌组织单糖基神经酰胺(CerG1)、脂肪酸(FA)、溶血磷脂酰甘油(LPG)、溶血磷脂乙醇胺(LPE)、溶血磷脂酰丝氨酸(LPS)、辅酶(Co)、磷脂酰甘油(PG)、神经酰胺(Cer)、磷脂酰乙醇胺(PE)、鞘氨醇(So)、甘油二酯(DG)、心磷脂(CL)、磷脂酰胆碱(PC)、甘油三酯(TG)、酰基肉碱(AcCa)、磷脂酰肌醇(PI)和磷脂酰丝氨酸(PS)丰度上调,溶血磷脂酰胆碱(LPC)、鞘磷脂(SM)、溶血磷脂酰肌醇(LPI)、单半乳糖基二酰甘油酯(MGDG)丰度下调;筛选出16种差异脂质分子,其中去势组胸肌组织PE(18∶1p/20∶4)、PE(18∶0/18∶1)、PE(38∶2p)、PE(18∶0e/22∶6)、PC(38∶6)、PC(34∶1e)、PS(41∶4)、PS(18∶0/22∶4)、LPC(22∶5)、LPI(20∶4)、PI(16∶0/20∶4)、Cer(d18∶1/24∶1)、Cer(d18∶1/24∶1)、TG(16∶0/8∶0/16∶0)丰度上调,PC(39∶5)和PI(16∶0/20∶3)丰度下调(VIP>1,P<0.05)。结果表明,去势促进武定鸡胸肌组织IMF沉积,影响脂质组成,改善肉质特性。

不同年龄梅花鹿肌内脂肪沉积规律及其对风味品质影响

旨在揭示不同年龄段梅花鹿肌内脂肪沉积规律,研究肌内脂肪含量对风味品质的影响。分别选取2、3、4岁梅花鹿母鹿,检测不同年龄段梅花鹿肌肉组织特性,并根据肌内脂肪(intramuscular fat, IMF)含量将样品分为高IMF组(IMFH组)和低IMF组(IMFL组),分析其对肌苷酸、脂肪酸含量以及脂肪酸结合蛋白4(FABP4)、脂肪酸合成酶(FASN)、甾醇调节元件结合转录因子1(SREBF1)和乙酰辅酶A羧化酶(ACACA)4种基因表达量。结果表明,梅花鹿肌内脂肪含量随年龄增长逐渐增加(P<0.001),里脊肌内脂肪含量最高(P<0.001),前腱子含量最低(P<0.001);梅花鹿年龄越长,肌纤维密度显著降低(P<0.05),肌苷酸、棕榈油酸(C16:1)、C18脂肪酸、饱和脂肪酸和单不饱和脂肪酸含量显著增高(P<0.05);高肌内脂肪样本肌纤维面积显著高于低肌内脂肪样本(P<0.05),IMFH组4岁龄梅花鹿肌束内肌纤维根数和肌苷酸以及3岁龄梅花鹿C16:1、C18:1和C18:3含量高于IMFL组(P<0.05),肌纤维密度高于IMFL组。油酸(C18:1)和亚麻酸(C18:3)含量高于低肌内脂肪样本(P<0.05);FABP4和SREBF1基因表达量显著高于低肌内脂肪样本(P<0.05),肌内脂肪与多不饱和脂肪酸呈负相关(P<0.05),与单不饱和脂肪酸呈正相关(P<0.05)。综上所述,梅花鹿随年龄增长,肉质嫩度降低,风味物质含量增加,高肌内脂肪组肉质更嫩,FABP4、FASN、SREBF1和ACACA四种基因高效表达和单不饱和脂肪酸含量对肌内脂肪沉积有促进作用。

PPARA基因对绵羊肌内脂肪沉积的影响及其多态性

为研究PPARA对绵羊肌内脂肪(IMF)沉积的影响及作用机制,寻找绵羊肌内脂肪沉积相关分子标记,以小尾寒羊(STH)和萨寒杂交(STH×SFK)F1群体为研究对象,通过测定其肉品质,利用H&E染色和油红O染色比较2个绵羊群体背最长肌组织学结构及脂滴分布;利用qRT-PCR和WB技术检测PPARA mRNA水平和蛋白水平在不同群体间的表达差异,并分析PPARA基因与肌内脂肪的相关性;Sanger测序技术检测PPARA基因SNP位点以评估其作为绵羊肌内脂肪沉积相关遗传标记的可能性。结果表明:小尾寒羊剪切力和失水率极显著高于萨寒杂交,但是pH值极显著低于萨寒杂交,大理石花纹评分小尾寒羊低于萨寒杂交群体;组织学染色显示,小尾寒羊肌纤维较粗,排列紧密,肌内脂肪在肌纤维间隙集中分布;萨寒杂交肌纤维较细且结构松散,肌内脂肪在肌细胞间及肌纤维间隙均匀、广泛分布,含量更高;PPARA mRNA表达量小尾寒羊群体显著高于萨寒杂交群体,PPARA蛋白表达量小尾寒羊群体极显著高于萨寒杂交群体;相关性分析显示,PPARA基因表达量与绵羊脂滴面积比及pH值呈极显著负相关,与剪切力和失水率呈极显著正相关,与大理石花纹评分弱相关;Sanger测序结果分析显示,2个绵羊群体PPARA基因第2内含子T49885C、T50007C、G50013A、G50835A、G50942A及G51154C位置上发生碱基突变,但小尾寒羊群体未检测到C49885T突变。SNP遗传多样性分析显示,SNP位点群体纯合度均大于杂合度,在群体中处于中低度多态;除G50835A突变偏离了Hardy-Weinberg平衡,其余SNPs均符合Hardy-Weinberg平衡,遗传基础稳定。研究认为,PPARA基因对绵羊肌内脂肪沉积具有重要影响,可作为绵羊肌内脂肪性状选择的潜在分子遗传标记。

猪肌内脂肪沉积的影响因素及非编码RNA对其调控的研究进展

肌内脂肪(intramuscular fat,IMF)俗称“大理石纹”,是猪肉脂肪组织的重要组成部分,可以改善肉的嫩度、多汁性,提升肉的风味,是评价猪肉品质的重要指标。IMF主要分布在肌纤维或肌纤维束间,由三酰甘油、磷脂和胆固醇组成,受遗传、营养、环境等因素的影响。文章对影响猪IMF沉积的主要因素及非编码RNA(non-coding RNA,ncRNA),包括微小RNA(microRNA,miRNA)、长链非编码RNA(long non-coding RNA,lncRNA)和环状RNA(circular RNA,circRNA)]在猪IMF沉积中的作用进行综述,旨在为深入研究猪脂肪沉积的分子机制提供理论基础。

宁乡猪不同发育阶段肌内脂肪沉积差异表达基因及其调控通路分析

【目的】分析不同日龄宁乡猪背最长肌组织mRNA表达谱,筛选发育过程中与脂肪沉积相关的差异表达基因及其所参与的信号通路,并确定部分关键基因在肌内脂肪发育过程中的表达特征。【方法】选取30(D30)和250(D250)日龄宁乡猪各3头,采集背最长肌组织样品提取总RNA进行转录组测序,对测序数据进行比对和处理,筛选参与脂质代谢的差异表达基因进行GO功能、KEGG通路及蛋白互作分析,并随机选取6个差异表达基因进行实时荧光定量PCR验证。【结果】共筛选出30个与脂质代谢相关的差异表达基因,其中9个上调,21个下调。差异表达基因主要富集在脂肪酸氧化、长链脂肪酸代谢等生物过程,线粒体、细胞器膜等细胞组分,酰甘油O-酰基转移酶活性、氧化还原酶活性等分子功能;参与了脂肪酸降解、甘油酯代谢、PPAR等信号通路。蛋白互作分析筛选出ACSL 1、ACAA 2、HADHB、LIPG、GPCPD 1、ALDH 2等关键蛋白基因处于核心位置,通过其mRNA表达量不同参与脂肪沉积调控。ACSL 1、CPT 1 A等6个基因的实时荧光定量PCR验证结果与转录组测序结果一致。【结论】ACSL 1、ACAA 2、HADHB、LIPG、GPCPD 1、ALDH 2等作为核心基因参与宁乡猪肌内脂肪调控,并通过脂肪酸降解、甘油酯代谢等信号通路发挥调控作用。本研究结果为进一步研究猪肌内脂肪沉积相关基因的分子调控机制提供了理论参考。