干扰lnc23后牛骨骼肌卫星细胞转录组测序的生物信息学分析

试验旨在分析lnc23在调控牛骨骼肌卫星细胞分化过程中转录组水平的变化,筛选出可能参与调节骨骼肌卫星细胞生长的调控通路及相关mRNAs。采用第二代测序技术（next-generation sequencing,NGS）基于Illumia hiSeq测序平台对成功构建的lnc23抑制模型及相应对照组的牛骨骼肌卫星细胞进行转录组测序,将数据整理、过滤及评估后,通过生物信息学方法分析样品间基因转录差异表达,对这些差异基因进行GO和KEGG富集分析,并应用实时荧光定量PCR技术对转录组数据结果进行验证。结果显示,转录组测序共鉴定到19 358个基因,筛选到1 297个差异表达基因,其中上调856个,下调441个。差异基因的GO功能分析共包括细胞组分、分子功能和生物学过程3大类222个分支,其中有大量的差异基因与催化活性、分子功能调节、信号转导、生物黏附、新陈代谢相关。KEGG分析显示,差异基因共涉及190个通路,显著富集在PI3K-Akt、P53、TNF、RIG-Ⅰ样受体、神经活性配体受体互作、细胞因子互作等信号通路上,进一步从中筛选出可能参与细胞生长、肌肉发育过程的差异基因,如CCNA2、RRM2、IL-6、MYL2等。实时荧光定量PCR结果显示,所选的11个差异基因中有9个与转录组测序结果变化一致,表明了测序结果的可靠性。本试验完成了干扰lnc23及其对照后牛骨骼肌卫星细胞的转录组测序分析,获取差异基因的功能注释信息,初步揭示lnc23调控牛骨骼肌卫星细胞分化的潜在基因和通路,为深入探究lnc23调控牛骨骼肌卫星细胞的分化机制打下良好的基础。     

白斑狗鱼(Esox lucius Linnaeus)的骨骼结构

采用传统烧煮法及软骨和硬骨双染色法,对白斑狗鱼骨骼结构进行观察。结果显示其骨骼结构有如下特点:(1)白斑狗鱼的中轴骨骼和附肢骨骼未完全骨化。(2)脑颅骨骼中除背面和腹面的膜骨如副筛骨、鼻骨、额骨、顶骨、犁骨、副蝶骨外,中间为未完全骨化的脑箱,有数个骨化中心,分别分布在中筛骨、蝶耳骨、翼耳骨、上枕骨、基枕骨、外枕骨,前耳骨区域,骨化程度不一。(3)咽颅中,包括完全骨化的颌弓和不完全骨化的舌弓及鳃弓,其中,舌弓中续骨呈宽扁三角形,并以其较宽的侧、下边将舌颌骨与后翼骨、翼骨和方骨紧密连接;有5对鳃弓,第5对鳃弓为一对棒状骨,与表面密布细齿的长条状骨片以结缔组织相贴。(4)白斑狗鱼共有62节椎骨,其中尾椎19节,为双凹型椎体。具有背肋和腹肋,前10个躯椎的髓棘呈片状;躯椎无真正的髓弓,所谓椎管只是由致密结缔组织将髓棘基部包裹而成,保护脊髓;每个尾椎的左右髓弓闭合成椎管,左右髓棘愈合为一;椎体无前后关节突,但每个椎体间具有发达的结缔组织粘附。(5)附肢骨骼中背鳍、臀鳍的支鳍骨分别为19、16个;尾鳍介于正型尾与歪型尾之间,最后3枚尾椎渐上翘,最后1枚尾椎具1个尾上骨,5个尾下骨,第2个尾下骨分叉;倒数第2个脉棘宽扁呈扇状。尾鳍由后8个椎骨的髓棘和脉棘参与尾鳍支鳍骨的构成。肩带骨骼有膜骨的匙骨、上匙骨及未完全骨化的乌喙骨和肩胛骨构成,肩带的支鳍骨4个,较宽扁;腰带具有前后支鳍骨,形宽扃。观察结果表明白斑狗鱼的骨骼不仅有着与高等硬骨鱼相似的结构,也有着其自身特有的结构如副筛骨以及不完全骨化的脑颅、最后几枚尾椎上翘形成的半歪型尾、躯椎的椎管是由结缔组织构成等。这些结果对于研究狗鱼的演化及分类地位有一定的意义。     

MSTN基因对牛肌动蛋白细胞骨架调节通路的影响

为探究肌肉生长抑制素（myostatin,MSTN）对牛骨骼肌生长发育的作用机制,本研究前期利用定量蛋白质组学与磷酸化蛋白质组学分析野生型蒙古牛（MG.WT）和MSTN^+/-蒙古牛（MG.MSTN^+/-）腿臀肌肌肉组织中蛋白质水平和磷酸化修饰水平的差异变化,使用已建立的牛骨骼肌卫星细胞体外诱导成肌分化模型,检测设计合成的MSTN siRNA （si-MSTN）干扰效果;采用实时荧光定量PCR和Western blotting方法检测转染si-MSTN的增殖期（GM）和分化第3天（DM3）牛骨骼肌卫星细胞中肌动蛋白细胞骨架调节通路相关基因的mRNA和蛋白水平的表达变化,研究敲低MSTN表达对肌动蛋白细胞骨架调节通路的影响。结果显示,在MSTN^+/-蒙古牛肌肉组织中共鉴定到16个肌动蛋白细胞骨架调节通路相关基因表达丰度上调;转染si-MSTN细胞中的MSTN表达水平极显著降低（P<0.01）;在转染si-MSTN的GM期牛骨骼肌卫星细胞中,肌动蛋白细胞骨架调节通路相关基因ENAH、ACTN4和Cdc42的mRNA水平均显著升高（P<0.05）,PFN1、RhoA和ACTN4的蛋白水平均显著或极显著升高（P<0.05;P<0.01）;在转染si-MSTN的DM3牛骨骼肌卫星细胞中,ENAH、CFL1、SCIN和Cdc42基因mRNA水平均显著升高（P<0.05）,RhoA基因mRNA水平极显著升高（P<0.01）,PFN1和ACTN4的蛋白水平均显著升高（P<0.05）。结果表明,干扰MSTN可以促进肌动蛋白细胞骨架调节通路相关基因的表达,探明了MSTN可能通过介导肌动蛋白细胞骨架调节通路影响牛骨骼肌卫星细胞增殖和成肌分化的分子机制,为进一步研究MSTN对牛成肌分化的调控机制提供参考。     

运输应激猪骨骼肌中热应激蛋白HSP70和HSP90家族的表达

利用Western blot技术，检测长途运输试验猪骨骼肌（背最长肌和臀长肌）中分属于HSP70家族和HSP90家族的4种应激蛋白（HSP70，HSP72，HSP86和HSP90）的表达，所有运输应激猪和对照猪肌肉组织 中均检测到了上述4种HSP，对照猪组织中HSP的表达说明HSP除了在受应激 的细胞内行使生理功能外，还具有独立于应激刺激应答以外的其它作用，6h长途运输后，HSP的表达量明显不同，HSP70和HSP72在肌肉组织中的表达虽然有一定的增加，但统计学分析差异不显（P＞0．05），而HSP86和HSP90在骨髓肌中的表达明显下降，尤以HSP90下降最显（P＜0．01），提示HSP90家族成员与肉品品质相关，可能作为判应激损伤的的指征。     

秦川牛胎儿骨骼肌卫星细胞的分离培养

【目的】探索胎牛骨骼肌卫星细胞分离、培养、鉴定及基因转染的方法。【方法】分别采用Ⅰ型胶原酶消化、Ⅰ型胶原酶与胰蛋白酶二步消化及链霉蛋白酶消化法对胎牛骨骼肌卫星细胞进行培养,比较了3种不同分离方法所得细胞数及其存活率的差异;利用差速贴壁法和Percoll密度梯度离心相结合的方法纯化骨骼肌卫星细胞,对纯化后的细胞进行myostatin基因RT-PCR以及结蛋白(Desmin)免疫细胞化学染色鉴定,最后通过电转染法对纯化的骨骼肌卫星细胞进行EGFP基因转染研究。【结果】3种消化培养方法中,以链霉蛋白酶消化法分离得到的胎牛骨骼肌卫星细胞数显著高于其它2种方法(P0.05),但细胞存活率较低(P0.05);而采用Ⅰ型胶原酶与胰蛋白酶二步消化法可以得到相对较高的细胞数及存活率。利用差速贴壁和Percoll密度梯度离心相结合的方法可以得到纯化的骨骼肌卫星细胞;电转染法适用于骨骼肌卫星细胞的基因转染。【结论】建立了胎牛骨骼肌卫星细胞分离、培养、纯化、鉴定及基因转染的方法,为通过转基因方法改良秦川牛产肉性能研究奠定了基础。     

Effects of DHRS3 in C2C12 Myoblast Differentiation and Mouse Skeletal Muscle Injury

Myoblast differentiation is an essential process during skeletal muscle development. C2 C12 myoblast is a commonly used experimental model to study muscle cell differentiation in vitro. Dehydrogenase/reductase(SDR family) member 3(DHRS3) is a highly conserved member in short-chain alcohol dehydrogenase/reductase superfamily and has been shown to be involved in the metabolism of retinol. Previous experimental results showed that the expression of DHRS3 increased significantly during the differentiation of myoblasts differentiation. However, the effect of DHRS3 on mouse muscle cell differentiation was unclear. The objective of current study was to determine if DHRS3 affected muscle cell differentiation, and if DHRS3 was involved in muscle regeneration. Protein expression was determined by western blot and immunofluorescence analysis. The activation and inhibition of DHRS3 increased and decreased C2 C12 myoblast differentiation respectively, which indicated that DHRS3 could affect C2 C12 myoblast differentiation. DHRS3 expression was significantly changed during muscle regeneration, with the regeneration of muscle injury, the expression of DHRS3 tended to increase first and then decrease. It suggested that DHRS3 might be involved in muscle regeneration. In summary, this study confirmed the involvement of DHRS3 in C2 C12 myoblast differentiation and mouse skeletal muscle regeneration and provided a theoretical basis for further elucidating the molecular mechanism of muscle development.     

Sequential expression of myogenic regulatory factors in bovine skeletal muscle and the satellite cell culture

Myogenic regulatory factors (MRFs) are important in the control of skeletal muscle development. To understand myogenic regulation by MRFs in bovine adult muscle cells, their expressions, namely that of Myf5, MyoD, myogenin, and MRF4 in the biceps femoris muscle (BF) and in the satellite cell culture, were analyzed by RT-PCR. In the BF, all four MRFs were expressed and in particular, myogenin and MRF4 were strongly expressed, whereas Myf5 was faintly expressed. The satellite cells prepared from the BF expressed Myf5, but only a trace of MyoD, at day 9 of culture. During the growth of the cells to day 14, the MyoD and myogenin expressions gradually increased, and that of MyoD expression reached its maximum at the confluence of the culture. After induction of myogenic differentiation by a serum-free medium at day 14, Myf5 expression gradually decreased, and the up-regulated expression of MyoD was suppressed, whereas myogenin expression continued to increase sharply. Following the myogenin expression, MRF4 also drastically increased toward the myotube formation of the cells. When huge myotubes were formed at day 18, Myf5 was expressed at a low level, whereas the MyoD expression remained at a moderate level.     

Symmorphosis and livestock bioenergetics: production animal muscle has low mitochondrial volume fractions

A comparative analysis of skeletal muscle structure reveals that production species (nine species, representing three mammalian families and an avian family) have mitochondrial volume fractions (MVF) 37% lower than the non‐production species at equivalent size (17 species, with representatives from 10 mammalian families) ( Fig. 1 ; F_1,25 = 4.79; p = 0.039). As MVF provides evidence of oxidative capacity, this comparative analysis indicates that production animals share an exceptionally low oxidative capacity muscle phenotype. A possible bioenergetic reason for this observation, relating to a reduction in the cost of maintaining trans‐membrane ion gradients is briefly discussed. This discussion is framed within a biological economic design theory called symmorphosis and makes predictions about avenues for improvements in livestock bioenergetics.

Figure 1 Open in figure viewer PowerPoint The scaling of log skeletal muscle mitochondrial volume density (MVF) with log endotherm size. Production species (PS) (red circles, red line) have a 37% lower MVF than non‐production species (NPS) (blue circles, blue line). NPS log MVF = ?0.11 log M_b + 0.88 (r² = 0.48, n = 17). PS log MVF = ?0.11 log M_b + 0.74 (r² = 0.69, n = 9).