大鼠和家兔生后发育各阶段比目鱼肌纤维的比较

为研究大鼠与家兔骨骼肌各类型肌纤维的数量和二维分布以及生后发育对其影响,取生后2d和2、4、6、8、10周龄(体重10g和32、95、190、280、320g)大鼠及生后2d和2、4、8、12、16、20、24周龄(体重100g和220、400、750、1200、1600、2100、2500g)家兔的比目鱼肌做琥珀酸脱氢酶染色。实验结果表明,大鼠和家兔比目鱼肌纤维被分成Ⅰ型(SO),ⅡX型(FO)和ⅡA型(FOG)3型。使用图像分析系统分析每型肌纤维在生后发育各阶段的相关变化,大鼠和家兔比目鱼肌中：Ⅰ型纤维分布于整块肌肉,其数量随着生后发育而增加。幼体ⅡX型纤维分布在整块肌肉中,其数量随生后发育而减少;ⅡA型分布在肌肉中深层,数量几乎无变化;至成体时只有少量的ⅡX和ⅡA分布在肌表层。整个发育期间未见ⅡB型纤维。ⅡA型纤维直径最大,Ⅰ型中等,而ⅡX型最小。家兔3型肌纤维的平均横切面积比大鼠的大。这些结果表明大鼠和家兔后肢肌各种类型肌纤维的数量比例和分布随生长过程发生改变。     

家兔与大鼠腓肠肌的生后发育比较

研究分析了家兔、大鼠腓肠肌在生后各年龄阶段的内侧头、外侧头的内侧亚体、中间亚体或外侧浅亚体、外侧亚体或外侧深亚体内快慢肌纤维的发育情况，应用大体解剖结合组织化学方法确定了其肌亚体，并进行琥珀酸脱氢酶染色、图像分析两型肌纤维的直径特征，以及肌构筑学与肌诱发电位的测量。结果表明：家兔在生后1个月时，内侧亚体从其深面凸现于内侧头与外侧亚体之间，中间亚体居于内侧亚体远端；大鼠内侧头未能区分肌亚体，其外侧头分为内侧亚体、外侧浅亚体，而外侧深亚体居于外侧浅亚体的深面呈重叠状：生后2、3天均未能分出Ⅰ、Ⅱ型肌纤维，也未见有原始肌束；Ⅰ、Ⅱ型肌纤维比例随年龄增长而变化，内侧亚体的Ⅱ型肌纤维比例在家兔与大鼠的生后发育中始终占优，而在其它各肌亚体内，Ⅱ型肌纤维的比例在发育中不恒定，直至成年后Ⅱ型肌纤维才趋于稳定并占优。在生长发育过程中，各肌亚体内Ⅱ型肌纤维的直径在各年龄段均大于Ⅰ型肌纤维。生后6个月家兔外侧头内侧亚体(FL／CSA)比值越大，倾向于速度型构筑；内侧头、中间亚体和外侧亚体(CSA／MW)比值越大，倾向于力量型构筑。大鼠腓肠肌外侧头内侧亚体乙酰胆碱酯酶染色显示葡萄状运动神经末梢支配慢肌纤维，斑点状运动终板位于快肌纤维。     

大鼠生后发育期间胰腺IAPP免疫组织化学定位研究

本文应用免疫组织化学ＰＡＰ法对正常雄性Ｗｉｓｔａｒ大鼠生后发育期间胰腺ＩＡＰＰ－ＩＲ阳性细胞进行了定位研究。结果表明;生后１天的大鼠胰岛内即已存在ＩＡＰＰ－ＩＲ阳性细胞,双染法证实ＩＡＰＰ与胰岛素共存于胰岛Ｂ细胞的胞质内。ＩＡＰＰ细胞免疫反应强度随生后发育而变化,２８天以后趋于稳定。胰腺外分泌部也有散在的ＩＡＰＰ－ＩＲ细胞。本文初步探讨了上述结果的生物学意义。     

小鼠胚胎及生后发育的肾上腺皮质的组织学与组织化学研究

胚龄１３日小鼠肾上腺结构尚未形成,在肾附近可见两群细胞。１５日两群细胞融合,呈一新月形小体,外包被膜,内含两类细胞,一类胞体较大,染色较深,另一类胞体较小,染色浅。１７日,胞体大染色深的细胞形成团索状,发育成皮质细胞;另一类细胞则迁移至中央,形成髓质。组织化学研究显示,胎龄１５日及以后的肾上腺皮质细胞３β－羟甾体脱氢酶（３β－ＨＳＤＨ）、脂类、酸性磷酸酶（ＡＣＰ）、亮氨酸氨基肽酶（ＬＮＡｓｅ）均为阳性。以上一些酶活性的出现提示１５日及其后胚鼠,生后１～６０天小鼠的肾上腺皮质都有分泌甾体激素之功能。     

生后发育过程中大鼠下丘脑NMDA受体各亚单位mRNA基因表达

中枢NMDA受体通道具有一种独特的门控方式,既受配基门控又受电压门控,而这种独特的门控通道又必须由各种亚单位形成的多样化的异寡聚体才具有一定的活性和功能.从胚胎形成到生后发育,中枢NMDA受体各亚单位及其所组成的异寡聚体具有各自不同的时空特性,其功能以及药理学特性也随发育过程而变化.本研究应用RT-PCR技术,研究在生后发育过程中听觉中枢神经系统下丘NMDA受体NR1、NR2A、NR2B和NR2CmRNA基因的表达,以期为在分子水平上揭示其在生后发育过程中的规律.     

大鼠脑干听觉诱发电位和中潜伏期反应的生后发育

目的：探讨大鼠脑干听觉诱发电位（BAEP）和听觉中潜伏期反应(MLR)生后发育模式的异同。方法：在同一批新生SD纯种大鼠连续10周同时观察BAEP和MLR生后发育的变化。结果：BAEP和MLR分别在生后14d和17d出现;BAEP各波峰潜伏期（PL）随鼠龄增长而递减,生后3－4周是PL缩短的主要时期,I波PL在生后29d达成年值,其余各波PL在生后70d全部达成年值;首次出现的MLR,其Po和Na两波PL已达成年值,而Pa、Nb和Pb和PL也随鼠龄增长而缩短,但生后20－23d很快就达成年值;BAEP的Ⅰ、Ⅲ、Ⅳ波和MLR的Nb、Pb波波幅在生后3－4周期间迅速递增,且峰值明显大于成年值,然后逐渐回降。结论：大鼠MLR和BAEP生后发育的模式基本相同,但MLR各波PL较早达成年值。     

大鼠生后发育过程中听皮层神经元特征频率的可塑性

应用常规电生理学技术,以神经元的特征频率和频率调谐曲线为指标,分别在生后2、3、4、5、6和8周龄SD大鼠上,研究生后发育过程中,听皮层神经元特征频率的可塑性.结果表明,在给予条件刺激频率和神经元特征频率相差1.0kHz范围内,条件刺激都可诱导各年龄组神经元特征频率向频率调谐曲线的低频端、高频端或调谐曲线的两端相应的偏移.特征频率偏移的概率与年龄相关.随着年龄的增长,特征频率偏移的比例下降,而不偏移的比例则上升.随着年龄增长,那些Q10-dB值大和频率调谐曲线对称指数大于零的神经元,特征频率偏移到频率调谐曲线高频端的比例增加更为明显(P<0.01).诱导特征频率完全偏移的时程和特征频率恢复的时程也与动物的年龄相关,随着年龄增长,诱导和恢复时程都明显延长(P<0.05).结果提示,大鼠听皮层神经元特征频率的可塑性与生后年龄相关,为深入研究中枢神经元功能活动可塑性的机制提供了重要实验资料.     

大鼠生后不同时期心肌NGF mRNA水平的变化

神经生长因子 (ｎｅｒｖｅｇｒｏｗｔｈｆａｃｔｏｒ,ＮＧＦ)是最早发现的神经营养因子 ,对于神经元的发育、分化、维持正常功能具有极重要的作用。研究表明 ,ＮＧＦ也参与免疫、造血、生殖、心血管等功能的调节。以往的研究证实 ,心肌细胞可以分泌ＮＧＦ。多年来 ,人们对ＮＧＦ在心脏方面的作用进行了较为深入的研究 ,但迄今为止 ,尚未见有关生后发育过程中正常心肌ＮＧＦｍＲＮＡ表达方面的报道。本研究采用ＲＴ ＰＣＲ(ｒｅｖｅｒｓｅｔｒａｎｓｃｒｉｐｔｉｏｎ ｐｏｌｙｍｅｒａｓｅｃｈａｉｎｒｅａｃｔｉｏｎ)方法 ,半定量分析大鼠生…     

胚胎及生后不同发育时期大鼠睾丸生殖细胞的凋亡

目的 探索雄性生殖细胞在发育过程中凋亡的特征和规律。方法 利用改进的石蜡切片原位末端标记法（TUNEL法）观察SD大鼠睾丸生殖细胞,对胚胎及生后不同阶段生殖细胞凋亡进行研究。结果 胚胎第13.5天原始生殖细胞即有较高的凋亡率,胚胎第19.5天到出生后第1天,未检测到凋亡生殖细胞,出生后第7天精原细胞分裂增生,伴有较高的凋亡率,与其他各年龄组有显著性差异。出生后第14天精母细胞凋亡率最高,与其他日龄组有显著性差异。结论 SD大鼠雄性生殖细胞发生,发育,成熟过程中都存在凋亡,主要发生在处于细胞增殖过程中的原始生殖细胞,精原细胞和初级精母细胞。     

大鼠生后视上核加压素分泌的发育

血管加压素是下丘脑加压素能神经元分泌的九肽激素,我们应用光镜,免疫细胞化学和图像分析技术,对大鼠生后视大核加压素能神经元分泌加压素的发育变化进行了跟踪研究,结果表明,新生仔鼠已开始分泌加压素,数据经统计学处理,表明新生组与1周,3周与4周组存在显著性差异。     

Measurement of Maximum Isometric Force Generated by Permeabilized Skeletal Muscle Fibers

Analysis of the contractile properties of chemically skinned, or permeabilized, skeletal muscle fibers offers a powerful means by which to assess muscle function at the level of the single muscle cell. Single muscle fiber studies are useful in both basic science and clinical studies. For basic studies, single muscle fiber contractility measurements allow investigation of fundamental mechanisms of force production, and analysis of muscle function in the context of genetic manipulations. Clinically, single muscle fiber studies provide useful insight into the impact of injury and disease on muscle function, and may be used to guide the understanding of muscular pathologies. In this video article we outline the steps required to prepare and isolate an individual skeletal muscle fiber segment, attach it to force-measuring apparatus, activate it to produce maximum isometric force, and estimate its cross-sectional area for the purpose of normalizing the force produced.     

Postexercise Muscle Triacylglycerol and Glycogen Metabolism in Obese Insulin‐Resistant Zucker Rats

Objective: To determine the impact of insulin resistance and obesity on muscle triacylglycerol (IMTG) and glycogen metabolism during and after prolonged exercise. Research Methods and Procedures: Female lean (fa/?; N = 40, ZL) and obese insulin-resistant (fa/fa; N = 40, ZO) Zucker rats performed an acute bout of swimming exercise (8 times for 30 minutes) followed by 6 hours of carbohydrate supplementation (CHO) or fasting (FAST). IMTG and glycogen were measured in the extensor digitorum longus (EDL) and red vastus lateralis (RVL) muscles. Results: Despite resting IMTG content being 4-fold higher in ZO compared with ZL rats, IMTG levels were unchanged in either EDL or RVL muscles immediately after exercise. Resting glycogen concentration in EDL and RVL muscles was similar between genotypes, with exercise resulting in glycogen use in both muscles from ZL rats (∼85%, p < 0.05). However, in ZO rats, there was a much smaller decrease in postexercise glycogen content in both EDL and RVL muscles (∼30%). During postexercise recovery, there was a decrease in EDL muscle levels of IMTG in ZL rats supplemented with CHO after 30 and 360 minutes (p < 0.05). In contrast, IMTG content was increased above resting levels in RVL muscles of ZO rats fasted for 360 minutes. Six hours of CHO refeeding restored glycogen content to resting levels in both muscles in ZL rats. However, after 6 hours of FAST in ZO animals, RVL muscle glycogen content was still lower than resting levels (p < 0.05). At this time, IMTG levels were elevated above basal (p < 0.05). Discussion: In both healthy and insulin-resistant skeletal muscle, there was negligible net IMTG degradation after a single bout of prolonged exercise. However, during postexercise recovery, there was differential metabolism of IMTG between phenotypes.     

Calibration of Quantitative Histochemical Methods: Estimation of Glycogen Content of Muscle Fibers Using the PAS Reaction

A fairly simple method for calibrating microdensitometric histochemical assays is described. The method is based on paired biochemical and histochemical assays on single freeze-dried skeletal muscle fibers which differ widely in their properties. As an example, the method is applied to investigate the validity of the periodic acid-Schiff (PAS) reaction for the microdensitometric estimation of glycogen content. Some problems that may interfere with the calibration are discussed.     

CNN3 Is Regulated by microRNA-1 during Muscle Development in Pigs

The calponin 3 (CNN3) gene has important functions involved in skeletal muscle development. MicroRNAs (miRNAs) play critical role in myogenesis by influencing the mRNA stability or protein translation of target gene. Based on paired microRNA and mRNA profiling in the prenatal skeletal muscle of pigs, our previous study suggested that CNN3 was differentially expressed and a potential target for miR-1. To further understand the biological function and regulation mechanism of CNN3, we performed co-expression analysis of CNN3 and miR-1 in developmental skeletal muscle tissues (16 stages) from Tongcheng (a Chinese domestic breed, obese-type) and Landrace (a Western, lean-type) pigs, respectively. Subsequently, dual luciferase and western blot assays were carried out. During skeletal muscle development, we observe a significantly negative expression correlation between the miR-1 and CNN3 at mRNA level. Our dual luciferase and western blot results suggested that the CNN3 gene was regulated by miR-1. We identified four single nucleotide polymorphisms (SNPs) contained within the CNN3 gene. Association analysis indicated that these CNN3 SNPs are significantly associated with birth weight (BW) and the 21-day weaning weight of the piglets examined. These facts indicate that CNN3 is a candidate gene associated with growth traits and regulated by miR-1 during skeletal muscle development in pigs.     

Molecular Profiling of DNA Methylation and Alternative Splicing of Genes in Skeletal Muscle of Obese Rabbits

DNA methylation and the alternative splicing of precursor messenger RNAs (pre-mRNAs) are two important genetic modification mechanisms. However, both are currently uncharacterized in the muscle metabolism of rabbits. Thus, we constructed the Tianfu black rabbit obesity model (obese rabbits fed with a 10% high-fat diet and control rabbits from 35 days to 70 days) and collected the skeletal muscle samples from the two groups for Genome methylation sequencing and RNA sequencing. DNA methylation data showed that the promoter regions of 599 genes and gene body region of 2522 genes had significantly differential methylation rates between the two groups, of which 288 genes had differential methylation rates in promoter and gene body regions. Analysis of alternative splicing showed 555 genes involved in exon skipping (ES) patterns, and 15 genes existed in differential methylation regions. Network analysis showed that 20 hub genes were associated with ubiquitinated protein degradation, muscle development pathways, and skeletal muscle energy metabolism. Our findings suggest that the two types of genetic modification have potential regulatory effects on skeletal muscle development and provide a basis for further mechanistic studies in the rabbit.     

Hedgehog信号通路与动物骨骼肌发育调控

Hedgehog信号通路在动物胚胎期及出生后骨骼肌的生长发育过程中发挥着重要作用。本文综述了Hedgehog信号通路对骨骼肌细胞增殖分化及肌纤维特性的调控作用及其在骨骼肌发育过程中与其它信号通路交互作用最新研究进展,为畜禽肉品质改良和肌肉相关疾病治疗提供理论基础。     

Isozyme Patterns of Lactate Dehydrogenase from Tissues of Mink and Arctic Fox during Postnatal Development

Isozymes of lactate dehydrogenase extracted from heart, kidney, and liver of mink (Mustela vison Briss.) and Arctic fox (Alopex lagopus L.) during postnatal development were separated by agarose gel electrophoresis. Tissue-specific isozyme pattern of lactate dehydrogenase can be revealed at the age of one month, while the definitive pattern is formed at the age of four months. The isozyme patterns of lactate dehydrogenase in the studied tissues of mink and Arctic fox share the properties specific for animal species of various ecogenesis.     

The JAK2/STAT3 Signal Pathway Regulates the Expression of Genes Related to Skeletal Muscle Development and Energy Metabolism in Mice and Mouse Skeletal Muscle Cells

The gene encoding a β-galactosidase from Entevobacter cloacae GAO was cloned and expressed in Escherichia coli. The nucleotide sequence of the insert of a positive clone had an open reading frame of 3084 bp that encoded a polypeptide of 1028 amino acid residues with a calculated molecular mass of 116,677 daltons. The amino acid sequence of β-galactosidase deduced from the nucleotide sequence, especially the sequence around the putative active site and of the fourteen regions, showed significant homology to β-galactosidases of other microorganisms, E. coli, Klebsiella pneumoniae, Lactobacillus bulgaricus, and Clostridium acetobutylicum.