影响宿主脂肪沉积的肠道微生物类别及其作用机理研究

猪体内脂肪沉积受遗传、饲粮、饲养管理和肠道微生物等多种因素的影响。脂肪沉积性状是重要的经济性状，过多的脂肪沉积影响胴体品质和饲料利用率。越来越多的研究表明，肠道微生物在宿主脂肪沉积中起重要作用。本文概述了猪肠道微生物的组成情况，在此基础上系统综述了已鉴别的影响猪脂肪沉积的肠道微生物种类，归纳了肠道菌群影响宿主脂肪沉积的可能机理，并根据国内外研究进展，总结了通过调控肠道微生物组成改善宿主脂肪沉积的方法，并展望将来的研究方向，旨在为将来通过调控肠道微生物来减少猪体内脂肪沉积、提高瘦肉率等提供参考。     

猪13号染色体上脂肪沉积相关QTL定位与候选基因研究进展

目前已有多个影响脂肪沉积的QTL定位于猪13号染色体上。作者综述了猪13号染色体脂肪沉积相关QTL的定位情况，并对该染色体上影响脂肪沉积的基因进行了介绍，以希望通过比较基因组学和位置候选克隆的方法，寻找猪脂肪沉积相关的候选基因，进而进行连锁分析或关联研究，找到适合在育种实践中进行应用的标记。     

猪肌内脂肪沉积的营养调控及候选基因的研究进展

营养调控和基因调控方法相结合是改善猪肌内脂肪沉积的根本途径,已经发现多种不同的营养素(如能量蛋白水平、甜菜碱、矿物质、维生素、共轭亚油酸等)对猪肌内脂肪沉积有重要的调控作用,但目前影响猪肌内脂肪沉积的主效基因并未确定。本文主要综述了不同营养素对猪肌内脂肪沉积的调控作用以及主要的候选基因对猪肌内脂肪沉积作用的研究进展。     

猪肌纤维性状形成和肌内脂肪沉积的遗传机制

近年来,通过改变肌纤维性状和肌内脂肪含量改善猪肌肉品质成为科学家们研究的热点。肌纤维性状形成和肌内脂肪沉积是内因与外因共同作用的结果。作者对猪肌纤维性状形成和和肌内脂肪沉积的遗传机制进行了综述,以期寻求调控及改善猪肌肉品质的方法。猪肌纤维性状形成和肌内脂肪沉积的遗传机制非常复杂,受基因、转录因子及信号通路的复杂网络调控。猪肌纤维的生长发育主要受生肌决定因子（myogenic determinant,MyoD）基因家族和肌肉生长抑制素（myostatin,MSTN）基因一正一负协同调控。能量感应网络AMPK/SIRT1/PGC-1α在猪肌纤维类型转化中起重要作用。脂肪沉积相关基因的表达量与猪肌内脂肪沉积有密切关系。随着分子生物技术的不断发展,许多与肌纤维性状形成和肌内脂肪沉积的相关基因已被鉴定出来,有助于进一步揭示猪肌纤维性状形成和肌内脂肪沉积的遗传机制。     

非编码RNA调控猪肌间脂肪沉积的研究进展

肌间脂肪含量与肉品质密切相关,决定着猪肉的风味、多汁性和嫩度等感官指标,因此,提高肌间脂肪沉积量对改善肉品质有重要作用。肌间脂肪沉积是一个复杂的生物学过程,受多种调控因子和成脂相关信号通路的影响,其中非编码RNA(non-coding RNA,ncRNA)对猪肌间脂肪沉积的调控作用引起了研究者的广泛关注。ncRNA是一类不编码蛋白质的RNA分子,在细胞增殖、分化、凋亡等多种生物学过程中发挥着调控作用。近年来研究表明,ncRNA中微小RNA(microRNA,miRNA)、长链非编码RNA(long non-coding RNA,lncRNA)和环状RNA(circular RNA,circRNA)均是肌间脂肪沉积的潜在调节因子,参与调控动物脂肪沉积过程。作者概述了ncRNA的生物学特性,介绍了肌间脂肪细胞的来源,总结了现阶段ncRNA在猪肌间脂肪沉积中的研究进展,以期为猪肉品质改良提供基础数据。     

陆川猪H-FABP基因克隆与序列分析

为了研究心型脂肪酸结合蛋白(H-FABP)基因与陆川猪肌内脂肪沉积的相关性,寻找猪脂肪沉积的主要候选基因,试验对陆川猪H-FABP基因进行了克隆与序列分析,参照Gen Bank已经公布的猪H-FABP基因序列(EF619344)设计引物,扩增克隆了陆川猪H-FABP基因的编码区序列,并应用DNAStar、Prot Scale等生物软件对其进行了序列分析和蛋白质二级结构预测。结果表明:陆川猪H-FABP基因编码区全长402 bp,编码133个氨基酸,碱基序列在235位点由A突变为G,并引起相应氨基酸由精氨酸转变为甘氨酸。其与野猪的亲缘关系最近,碱基同源性为99.3%;与人类、绵羊和家牛的碱基同源性也在90%以上。陆川猪H-FABP成熟肽包含有25.56%的α螺旋、12.03%的β转角、25.56%的无规卷曲和36.84%的延长线。说明H-FABP基因可作为研究陆川猪脂肪沉积的候选基因之一。     

联合多组学数据鉴定猪脂肪沉积的候选基因

脂肪沉积是猪生产及育种中最为重要的经济性状指标之一,其调控机制一直是研究热点,单一组学的研究方法不足以推测与还原出猪脂肪沉积复杂的调控过程。因此本研究联合多组学数据共同进行分析以鉴定猪脂肪沉积的候选基因。首先对同一猪场相同日龄和体重的461头大白猪进行基因分型,并将芯片数据填充至测序水平,然后对其中132个个体进行背最长肌mRNA测序,根据基因表达水平和包含15389322个SNP的测序数据进行eQTL分析鉴定到33756个cis-eQTL,且多为正向调控。之后基于猪的背膘厚度表型利用测序数据进行GWAS确定了312个显著SNP。最后通过GWAS与eQTL的共定位分析定位到一个显著信号位点SSC9:15828911,对应的调控基因为RAB30,且有研究表明其会参与脂肪的合成和代谢,可以作为影响猪脂肪沉积的候选基因。研究结果为猪脂肪沉积的遗传解析和猪肉质改良的分子育种提供理论依据和重要参考。     

RNA甲基化调控猪肉品质的研究进展

随着生活水平的提高，消费者对猪肉品质要求越来越高，如何提升猪肉品质是畜牧业生产中面临的重大课题。RNA甲基化修饰是真核生物中最丰富的一种表观遗传修饰，在多种生命过程中发挥重要的调控作用。越来越多的研究发现，脂肪沉积与猪肉品质密切相关，RNA甲基化对猪脂肪沉积具有一定的调控作用。因此，本文在概述了猪肉品质的影响因素和RNA甲基化生物学功能的基础上，阐述了RNA甲基化介导的转录后修饰对猪脂肪沉积的影响及调控机制等方面的研究进展，以期为调控猪肉品质、促进我国畜牧业高质量发展提供新思路。     

microRNA调控猪肌内脂肪沉积的研究进展

肌内脂肪（intramuscular fat,IMF）含量是评判猪肉品质的关键指标,其可影响猪肉的嫩度、剪切力、多汁性和风味等。微小RNA （microRNA,miRNA）是一类长度约为22 nt的短链非编码RNA,在胚胎发育、成脂分化、肌纤维形成、神经调节、免疫应答等多种生理过程中发挥重要作用。越来越多的研究表明,miRNA在猪肌内脂肪沉积过程中发挥重要调控作用,是脂质代谢的重要调控因子。作者通过归纳国内外关于miRNA调控猪肌内脂肪沉积的相关研究发现,miR-34a、miR-125a-5p、miR-32-5p等通过靶向作用转录因子Krüppel样因子（Krüppel-like factors,KLF）家族成员调控猪肌内脂肪沉积,miR-130a通过靶向作用过氧化物酶体增殖物激活受体（peroxisome proliferator activated receptor,PPAR）家族成员调控猪肌内脂肪沉积,miR-34a、miR-17-5p和miR-125a-5p等通过靶向作用其他家族成员,如长链酯酰辅酶A合成酶4（acyl-CoA synthetase long chain family member 4,ACSL4）、核受体共激活因子3（nuclear receptor coactivator 3,NCOA3）等来调控猪肌内脂肪沉积。然而miRNA调控猪肌内脂肪的具体作用机制尚不完全清楚,还需要进一步探究。作者通过梳理目前已经证实的与猪肌内脂肪沉积相关的miRNA,整理相关miRNA的靶基因以及主要作用通路,以期为筛选肌内脂肪相关miRNA提供参考,为改善肉质提供新的思路和策略,为阐明miRNA在猪脂质代谢中的作用机制提供参考。     

猪肌内脂肪沉积的影响因素及其研究进展

猪肌内脂肪的含量是影响猪肉品质的重要因素,它影响着肉的嫩度、风味和多汁性。猪肌内脂肪的调控机制很复杂．主要受营养、环境和基因等多方面影响。本文主要综述了影响猪肌内脂肪沉积的相关因素及其研究进展,为深入研究猪肌内脂肪沉积提供参考。     

The influence of urine and dung deposition on patch grazing patterns of cattle and sheep in the Southern Tall Grassveld

Abstract

The effect of urine and dung deposition on the patch grazing patterns of cattle and sheep in the Southern Tall Grassveld was investigated using an experiment with four treatments, viz. artificial urine, fresh cattle dung, fresh sheep dung, and a control. Cattle and sheep preferentially grazed the sward surrounding and within urine deposits for six months after deposition. Cattle rejected herbage from both cattle and sheep dung patches for six months after deposition. Sheep initially rejected the herbage from cattle dung patches, but their grazing patterns were no longer affected at six months after deposition. Sheep grazing tended not to be influenced by sheep dung. Urine deposition may consequently be an important factor in patch initiation and patch development.     

血管内皮生长因子A和B对动物脂肪沉积的调控作用研究进展

脂肪组织是构成动物胴体及肉品的重要组分,动物不同部位的脂肪沉积直接影响其胴体品质和肉品质。脂肪沉积的增加有两种途径:一是脂肪细胞数量的增加,即脂肪生成(adipogenesis);二是脂肪细胞体积增大,即肥大(hypertrophy)。血管内皮生长因子(vascular endothelial growth factor, VEGF)是调控血管和淋巴管生成的最重要因子之一。近年的研究发现,VEGF-A/B与机体脂肪沉积密切相关。因此,本文综述了VEGF-A/B及其受体对脂肪生成、代谢和沉积的调控作用研究进展,并对其在动物生产上的应用进行了展望,为研发调控动物不同部位脂肪沉积、提高动物胴体品质和肉品质的营养调控技术提供新的思路和科学依据。     

Amino acid and energy interrelationships in pigs weighing 20 to 50 kilograms: II. Rate and efficiency of protein and fat deposition

Two experiments were conducted to investigate the relationships between amino acids and DE for pigs weighing 20 to 50 kg. In Exp. 1, there were three dietary lysine levels that were either adjusted (1.50, 2.35 and 3.20 g/Mcal DE) for five DE levels (3.00 to 4.00 Mcal/kg) or unadjusted (.45, .71 and .96% of the diet) for three DE levels (3.50 to 4.00 Mcal/kg). In Exp. 2, diets containing six lysine:DE ratios (1.90 to 3.90 g/Mcal) at two DE levels (3.25 and 3.75 Mcal/kg) were fed. Pigs were housed individually, and could eat and drink ad libitum. When pigs weighed 50 kg, their empty body composition was determined by the urea dilution technique in Exp. 1 and by prediction equations based on backfat in Exp. 2. For the adjusted diets in Exp. 1, protein deposition and protein deposition:DE intake increased (P less than .01) slightly as DE levels increased. These criteria decreased linearly (P less than .001), and fat deposition increased (P = .11) as DE increased when lysine:DE ratios were not maintained. As lysine levels increased, protein deposition and protein deposition: DE intake increased (P less than .001) in both the adjusted and unadjusted diets. In Exp. 2, there was no effect of DE on either the rate or efficiency of protein deposition. Both protein deposition and protein deposition:DE intake increased (P less than .001) and fat deposition decreased as lysine:DE ratios increased up to 3.00 g lysine/Mcal DE. Protein deposition: lysine intake decreased (P less than .01) progressively as the lysine:DE ratio increased. Regression analyses indicated the protein deposition increased up to 3.00 g lysine/Mcal DE. The results demonstrate the need to adjust lysine according to energy levels and indicate that the optimum ratio for protein deposition was approximately 3.00 g lysine/Mcal DE (or 49 g of balanced protein/Mcal DE).     

家禽脂肪酸代谢及其在禽蛋中的沉积和营养调控

在肝脏中载脂蛋白作用下,内源合成或外源获取的脂肪酸以甘油三酯的形式同胆固醇及其他脂类组装形成极低密度脂蛋白(VLDL)。VLDL经血液循环到达卵巢,穿过卵母细胞外层屏障后,经卵母细胞受体介导的内吞作用进入卵母细胞发生沉积。而机体的营养状况或饲粮中营养成分的改变可通过影响脂肪酸的从头合成或VLDL结构直接或间接影响禽蛋中脂肪酸的最终沉积。本文阐述了家禽体内脂肪酸的来源、转运与沉积过程,并探讨了脂肪酸代谢及其在禽蛋中沉积的营养调控。     

模拟氮沉降对高寒湿地土壤理化性质和酶活性的影响

为研究氮沉降对土壤酶和土壤理化性质的影响,本研究在青海湖东岸开展野外控制试验,设计4个施氮水平0 g·m^-2,2 g·m^-2,5 g·m^-2和10 g·m^-2(分别为N0,N2,N5和N10),测定土壤养分和土壤酶活性。结果表明：氮沉降对土壤pH值和全磷含量无显著影响,硝态氮在浅层土中含量随施氮量的增加而逐渐下降,铵态氮在10 g·m^-2浅层土中含量显著高于其它处理,有机碳含量在2 g·m^-2处理下显著高于其它处理;酸性磷酸酶和脲酶随施氮量的增加活性显著升高,氮沉降抑制过氧化氢酶活性,碱性蛋白酶对氮沉降不敏感;相关分析表明,酸性磷酸酶、脲酶活性与铵态氮含量呈显著正相关关系,过氧化氢酶活性与硝态氮含量呈显著正相关关系,碱性蛋白酶活性与有机碳含量呈极显著正相关关系。本研究表明氮沉降影响高寒湿地碳、氮含量及其计量比,进而影响土壤酶活性。     

Histopathological Features of Cultured Japanese Amberjack Seriola quinqueradiata with Ascites Occurring in the Winter

A winter outbreak of ascites in cultured Japanese amberjack Seriola quinqueradiata was examined. Affected fish displayed bloody ascitic fluid in the peritoneal cavity, their hearts were covered with a white membrane, their livers were congested and their kidneys were swollen. Renal tubular epithelia displayed extensive necrosis and often contained hyaline droplets, while some glomeruli showed atrophy and necrosis. Hematopoietic tissue in the kidney contained some swollen reticular cells. In the heart, an inflammatory reaction accompanied by edema, hemorrhage and fibrin deposition occurred in the epicardium of the atrium and ventricle and in the pericardial cavity. The epicardium and pericardium were partially adhered to each other. Hepatic lesions included dilatation of sinusoids accompanied by severe edema and congestion. Edema and fibrin deposition were often observed in the hepatic serosa and perivascular tissue. Splenic tissues with atrophied pulp showed definite increases in trabecula thickness. These findings suggest that the examined fish might have a systemic circulatory disturbance due to cardiac lesions associated with renal failure.     

Validation of the periodicity of growth zone formation in the otoliths of four fish species from the Upper Zambezi ecoregion,southern Africa

In the Upper Zambezi and Okavango ecoregions, Brycinus lateralis, Hepsetus cuvieri, Schilbe intermedius and Serranochromis macrocephalus are important in subsistence fisheries, while S. intermedius and S. macrocephalus are often caught in commercial catches. Despite their importance, there is little information on their age and growth and age validation. Growth zone deposition rate in otoliths of B. lateralis, H. cuvieri, S. intermedius and S. macrocephalus was validated as annual using edge analysis in this study. Annual deposition of growth zones was corroborated by a fluorochrome marking experiment. Both methods demonstrated that one growth zone was deposited annually. Edge analysis demonstrated that the highest proportion of opaque zones was detected between August and December, most likely as a result of slow growth during lower temperature water during the preceding winter. With growth zone deposition validated as annual, future research should focus on determining the growth, maturity and mortality rates of these species, parameters which are important for their management.     

高温对家蚕蛾粘液腺生长发育及产附性的影响

试验了高温(五龄蚕31℃,蛹期34℃)对家蚕蛾粘液腺生长发育及产附性的影响。结果表明,高温导致粘腺长度缩短、干重减轻、腺体畸形;支部(分泌部)脆质中粗面内质网和线粒体数量减少,形态被破坏。粘液中的蛋白质及其氨基酸组成改变、含量减少是导致粘着力下降及产附性劣化的直接原因。二化性品种比多化性品种更易受高温影响。     

草地生态系统中家畜尿N转化研究

系统总结了放牧家畜尿N转化过程中,尿N矿化和NH3挥发,尿N硝化和反硝化作用,及其影响因素和相互关系。家畜尿N矿化作用快、持续时间短,尿沉积加速N矿化;NH3挥发速度为裸地>草地,单播草地>混播草地;NH3挥发对尿N损失起主导作用。硝化作用在尿沉积1周后才开始明显,存在明显时滞特性;NO3--N淋洗主要发生于畜尿沉积当年,草地植物对春施尿N的利用率比秋施尿N高;NO3--N淋洗为奶牛>绵羊,三叶草草地>混播草地>禾草草地。尿斑构成草地尿N反硝化作用的主体,反硝化作用产生N2O和N2,是尿N损失的另一主要因素。尿N损失随排泄尿N量的增加而增加。     

牦牛粪沉积下高寒草甸植物群落种间关联研究

植物群落构成和种间关联,反映物种在空间上的分布及相互依存和制约关系。为探究牦牛粪沉积和植被斑块互作下草地植物群落演变趋势及稳定性机制,以青藏高原东北缘高寒草甸禾草/杂类草斑块和嵩草/杂类草斑块为对象,分析牦牛粪沉积下两种斑块中主要植物种的重要值(IV)、Jaccard种间关联指数和Spearman秩相关系数的变化规律。结果表明,1)粪沉积使禾草/杂类草斑块的建群种扁穗冰草的IV增加和西北针茅的IV降低,嵩草/杂类草斑块的建群种线叶嵩草的IV降低;2)禾草/杂类草斑块中,粪沉积(DP)和对照(CK)的正负关联种对比为0.61和0.63,显著联结种对为6.6%和6.4%;嵩草/杂类草斑块中,DP和CK的正负关联种对比为0.90和0.72,显著联结种对为2.8%和14.5%;且二者显著联结的种对多存在于优势种或亚优势种与伴生种之间;3)两种斑块中多数种对间联结性弱,群落处于不稳定阶段;粪沉积使嵩草/杂类草斑块的稳定性增强,利于禾草/杂类草斑块的演变;4)依据优势种对环境的适应方式和主导生态因子,将两种斑块的群落植物种划分为喜阳耐旱植物、喜阴喜湿植物和喜阳喜湿植物三大生态种组。