多不饱和脂肪酸对机体脂肪代谢基因表达调控研究进展

随着生物技术的发展，人们逐渐认识到多不饱和脂肪酸除了作为生物机体必要营养素外，还对机体内某些基因的表达起着重要调控作用。因此日粮添加多不饱和脂肪酸的目的不仅仅局限于改变生物机体细胞膜成分、细胞内钙离子浓度、类前列腺素等活性物质，更重要的是多不饱和脂肪酸和其代谢物能在细胞水平上通过与核受体和转录因子结合来对不同的基因表达进行调控。所以作者仅就现阶段多不饱和脂肪酸对生物机体基因表达调控研究现状作一简要综述。     

lncRNA作为竞争性内源分子的作用机制及研究进展

竞争性内源RNA （competing endogenous RNA,ceRNA）假说提出具有相同短序列非编码微小（microRNA,miRNA）应答元件（microRNA response element,MRE）的转录物通过竞争的方式结合miRNA,从而影响转录物的表达水平。ceRNA假说颠覆了miRNA与靶基因单向调控的传统观念,在RNA调控网络中具有重要的生物学意义。在众多转录物中,长链非编码RNA （long non-coding RNA,lncRNA）是一类序列长度超过200个核苷酸的非编码RNA,对lncRNA的研究涉及到遗传、分子生物、基因调控、疾病（癌症、神经系统疾病等）等领域。miRNA与lncRNA形成了一个相互作用的调控网络,lncRNA可作为ceRNA抑制miRNA的功能,从而影响后续基因的表达。近年来,随着生物信息学技术的发展,科研人员发现ceRNA作用机制不仅涉及到人类癌症疾病,而且在各种复杂动物的肌细胞分化、脂肪细胞分化和颗粒细胞凋亡等生物过程中也发挥重要的调控作用。作者追溯了ceRNA调控机制,分析了ceRNA网络调控的影响因素,综述了ceRNA在不同动物中调控miRNA的研究进展,为进一步研究lncRNA与miRNA的调控网络提供参考,为畜牧业发展及复杂动物疾病治疗提供新的思路。     

植物microRNA的生物学功能及其在砧穗互作中的研究进展

microRNAs 在调控植物生长发育、胁迫应答和信号转导等方面发挥重要作用,是目前生物科学的研究热点。本文论述了植物miRNA的产生机理、特征、对靶基因的作用机制,及miRNA的生物学功能,对植物miRNA可通过嫁接进行长距离运输方面的研究进展进行了论述和讨论,并对开展嫁接对柑橘miRNA表达的影响,挖掘在砧穗间可转移的miRNA方面的研究进行了展望。     

miRNA调控鹿茸生长发育的研究进展

鹿茸是雄性鹿科动物(除驯鹿外)特有的能够周期性再生的器官,其生长发育受到多种因素的共同调控。miRNA(microRNA)是一类在真核生物中发现的内源性的具有调控功能的非编码RNA,在基因表达调控、细胞周期、生物体发育等方面发挥着重要的调控作用。本文从miRNA的相关技术、鹿茸组织中miRNA的鉴定、miRNA对生长因子的调控作用、miRNA对鹿茸细胞增殖的作用以及miRNA对鹿茸再生调控的研究几个方面就现有miRNA对鹿茸生长发育的研究进行总结和展望,为今后鹿茸生长发育机理的诠释具有一定的意义。     

microRNA let-7调控动物个体发育的研究进展

microRNA(miRNA)是一类广泛存在于多细胞动物中的进化保守的大小为18~25nt的非编码小分子RNA,可以通过与靶基因mRNA的非编码区(3′UTR)结合导致mRNA降解,或阻断mRNA翻译而调节基因表达。let-7是在线虫中发现的具有转录后调节功能的小分子RNA,具有高度的保守性,研究发现,let-7参与动物个体多个器官组织的发育过程。作者综述了近年来let-7参与调控脑、神经系统、心肺系统和肌肉发育等组织器官的研究成果,初步阐述了let-7调控组织器官发育的作用机制,以期为进一步探索let-7在动物体内的功能奠定基础。     

传染性法氏囊病病毒感染细胞内源性microRNA表达差异分析

细胞内源性microRNA（miRNA）在宿主与病原相互作用过程中发挥着重要的调节功能。为了分析细胞内源性miRNA与传染性法氏囊病病毒（IBDV）的相互作用,用IBDV弱毒和强毒分别感染鸡胚成纤维细胞（CEF）和SPF鸡,24h后,取感染CEF和法氏囊组织,提取细胞总RNA,用Hy3/Hy5双色荧光标记,与miRNA芯片杂交,进行芯片内标准化、芯片间标准化、表达差异比较以及聚类分析。结果显示：在IBDV弱毒感染的CEF中,有17个细胞内源性miRNA表达上调,17个miRNA表达下调;在IBDV强毒感染的鸡法氏囊组织细胞中,有30个细胞内源性miRNA表达上调,18个miRNA表达下调。根据表达差异显著的miRNA序列设计引物,用荧光定量RT-PCR方法验证芯片检测结果,2种方法的检测结果一致。结果表明,IBDV感染可诱导细胞内源性miRNA表达变化,这些上调或下调的miRNA能调控细胞内多种代谢和信号传导途径发生异常,引起细胞及组织器官发生病理学变化。     

Characterization of microRNA profile in mammary tissue of dairy and beef breed heifers

MicroRNAs (miRNAs) are small non‐coding RNAs that participate in the regulation of gene expression. Their role during mammary gland development is still largely unknown. In this study, we performed a microarray analysis to identify miRNAs associated with high mammogenic potential of the bovine mammary gland. We identified 54 significantly differentially expressed miRNAs between the mammary tissue of dairy (Holstein‐Friesian, HF) and beef (Limousin, LM) postpubertal heifers. Fifty‐two miRNAs had higher expression in the mammary tissue of LM heifers. The expression of the top candidate miRNAs (bta‐miR‐10b, bta‐miR‐29b, bta‐miR‐101, bta‐miR‐375, bta‐miR‐2285t, bta‐miR‐146b, bta‐let7b, bta‐miR‐107, bta‐miR‐1434‐3p) identified in the microarray experiment was additionally evaluated by qPCR. Enrichment analyses for targeted genes revealed that the major differences between miRNA expression in the mammary gland of HF versus LM were associated with the regulation of signalling pathways that are crucial for mammary gland development, such as TGF‐beta, insulin, WNT and inflammatory pathways. Moreover, a number of genes potentially targeted by significantly differentially expressed miRNAs were associated with the activity of mammary stem cells. These data indicate that the high developmental potential of the mammary gland in dairy cattle, leading to high milk productivity, depends also on a specific miRNA expression pattern.     

miRNA在哺乳动物配子发生中的作用研究进展

哺乳动物配子发生的基因表达调控包括编码基因的阶段特异性表达调控及非编码基因的转录和转录后水平调控。微小RNA(microRNA, miRNA)作为一类小的非编码RNA, 通过识别靶基因非翻译区的结合位点, 导致mRNA降解或者蛋白质翻译抑制, 从而在转录后水平发挥调控作用。近年来, miRNA在哺乳动物生殖活动中的作用逐渐被揭示, 越来越多的研究表明, miRNA在哺乳动物精子发生、精子成熟、卵母细胞成熟、卵泡发育及早期胚胎发育等过程中都发挥着重要的调节作用, 其可通过调节支持细胞的增殖和凋亡或精原细胞、精母细胞及精细胞的细胞周期进程, 在精子发生的不同阶段发挥间接或直接调控作用, 也可通过调节卵母细胞、卵丘细胞以及颗粒细胞的增殖、凋亡、激素合成和细胞间作用, 对卵母细胞的发育和成熟过程进行调控。作者主要介绍了在哺乳动物配子发生过程中, miRNA的细胞和阶段特异性表达及其对靶基因的调节作用, 以期为深入研究哺乳动物配子发生的调控机制提供参考。     

鸭茅响应水淹胁迫的miRNA差异表达分析

水淹胁迫是限制我国西南地区鸭茅产量和品质提升的主要环境因子,已经成为一种不容忽视的非生物胁迫。鉴定鸭茅耐涝相关的功能基因,并探究其调控机制是鸭茅种质创新,提高鸭茅耐涝能力的必要途径。以鸭茅耐涝品种“滇北”为试验材料,分别经水淹胁迫处理0、8和24 h后,利用Illumina Hiseq测序平台对鸭茅叶片进行小RNA测序。结果表明,在水淹胁迫处理下共鉴定得到208个差异表达基因（DEGs）,经过筛选后有38个基因上调表达,34个基因下调表达,共占差异表达基因的34.62%。“滇北”鸭茅在水淹胁迫下差异表达基因主要属于miR166、miR167、miR159、miR396和miR156这5个miRNA基因家族。基于对差异miRNA进行靶基因预测及靶基因的GO和KEGG功能分析,发现这些靶基因主要参与细胞生理过程、代谢过程、IL-17信号通路、Th17细胞分化等植物逆境响应过程,为进一步揭示鸭茅在水淹胁迫下的分子调控机制提供了研究线索。     

Macronutrient intake of dogs,self‐selecting diets varying in composition offered ad libitum

The diet of the domestic dog has changed significantly from that of its wolf ancestor, with to date only two studies having examined macronutrient self‐selection in dogs. Whilst the first focused solely on protein intake, determining an intake of 30% metabolisable energy (ME ), the second investigated dietary protein, fat and carbohydrate (PFC ), indicating an intake ratio of 30:63:7% by energy. This study's aim was to further elucidate macronutrient intake by providing greater macronutrient range, energy content, and to investigate over a longer duration than previous studies. Fifteen adult dogs were given access to three wet diets providing 500% of daily ME , twice daily over 10 days. The diets were nutritionally complete and formulated using the same four ingredients in different proportions to supply high levels of protein (58% ME ), fat (86% ME ) or carbohydrate (54% ME ). Overall fat and carbohydrate consumption significantly declined from 6,382 to 917 kcals per day (p  < 0.001) and 553 to 214 kcals day^?1 (p  < .01) respectively. Protein intake, however, remained constant over the study and ranged from 4,786 to 4,156 kcals day^?1. Such results impacted on percentage total energy intake, with fat decreasing from 68% to 52% (p  < .001) and protein increasing from 29% to 44% (p  < .01). Our findings suggest that dogs still possess a “feast or famine” mentality, wherein energy dense fat is prioritised over protein initially. With continued feeding over 10 days, a transition to a more balanced energy contribution from both macronutrients is evident. The study also shows that given the option, dogs do not select carbohydrate to be a significant portion of the diet. The health implications of such dietary selection are of interest.     

Comparative rna-seq analysis of region-specific miRNA expression in the epididymis of cattleyak

The epididymis is the site of post-testicular sperm maturation, which constitutes the acquisition of sperm motility and the ability to recognize and fertilize oocytes. The role of miRNA in male reproductive system, including the control of different steps leading to proper fertilization such as gametogenesis, sperm maturation and maintenance of male fertility where the deletion of Dicer in mouse germ cells led to infertility, has been demonstrated. The identification of miRNA expression in a region-specific manner will therefore provide valuable insight into the functional differences between the regions of the epididymis. In this study, we employed RNA-seq technology to explore the expression pattern of miRNAs and establish some miRNAs of significant interest with regard to epididymal sperm maturation in the CY epididymis. We identified a total of 431 DE known miRNAs; 119, 185 and 127 DE miRNAs were detected for caput versus corpus, corpus versus cauda and caput versus cauda region pairs, respectively. Our results demonstrate region-specific miRNA expression in the CY epididymis. The GO and KEGG enrichment for the predicted target genes indicated the functional values of miRNAs. Furthermore, we observed that the expression of miR-200a was downregulated in the caput, compared with cauda. Since the family of miR-200 has previously been suggested to contribute to the distinct physiological function of sperm maturation in epididymis of adult rat, we speculate that the downregulation of miR-200a in CY caput epididymis may play an important role of sperm maturation in the epididymis of CY. Therefore, our findings may not only increase our understanding of the molecular mechanisms regulated by the miRNA functions in region-specific miRNA expression in the CY epididymis, it could provide a valuable information to understand the mechanism of male infertility of CY.     

An approach to assessment of the efficiency of dietary energy utilization by horses and ponies kept at riding schools.

The ratio of calculated net energy intake (NEi) to calculate net energy requirement (NEr) might serve as an indicator of the efficiency of dietary energy utilization. The ratio was determined for 93 horses and ponies from 10 riding schools. For each animal with an assumed constant body weight, energy intake and energy requirements were assessed. On average, the estimated NEi was 14% greater than NEr. There was a significant, negative association between crude fibre intake and the NEi: NEr ratio. Earlier work indicated that extra fat intake may lead to over estimation of the calculated energy value of the ration due to changes in macronutrient digestibility. Dietary fat concentration was found to range from 32 to 52 g/kg dry matter (5 to 6 g/MJ net energy), but on the basis of digestibility trials this range in fat concentration is too small to significantly influence the NEi: NEr ratio. This study shows that assessment of the efficiency of dietary energy utilization under normal conditions, on the basis of the NEi: NEr ratio is fraught with uncertainty.     

Dietary management of diabetes mellitus

Dietary therapy should be designed to enhance insulin therapy and improve glycaemic regulation of the diabetic dog and cat. Dietary therapy will not alleviate the necessity for insulin therapy in dogs and cats with insulin-dependent diabetes mellitus. Preliminary work suggests that dietary therapy may ultimately be the only therapy necessary to maintain glycaemic control in cats with suspected non-insulin-dependent diabetes mellitus. Currently, the feeding of a high fibre, high complex carbohydrate diet is recommended at a caloric intake designed to correct obesity and maintain ideal bodyweight. Several small meals should be fed during the period of insulin activity, to help minimise post prandial fluctuations in the blood glucose concentration.     

MicroRNA fingerprints in serum and whole blood of sarcoid‐affected horses as potential non‐invasive diagnostic biomarkers

Serum and whole blood microRNA (miRNA) fingerprints have been proposed as a new class of non‐invasive human cancer biomarkers. In this study, we compared equine sarcoid (ES) disease‐specific serum and whole blood miRNA fingerprints and correlated them to miRNA expression in sarcoid tissue. After high throughput sequencing, miRNA differential expression analysis between six ES‐affected and five control horses was carried out in serum and whole blood using a DESeq algorithm, accounting for the influence of hemolysis and the white blood cell count. Target gene, pathway prediction and enrichment analyses were conducted using TarBase, mirPath and GeneCodis. After exclusion of 4 hemolyzed out of a total of 11 serum samples, 9 miRNAs were found to be differentially expressed in serum of ES vs control horses. In whole blood, all 11 samples showed normal white blood cell counts and 19 miRNAs were found to be differentially expressed. A total of 2/9 serum and 7/19 whole blood differentially expressed miRNAs were also highly expressed at the tissue level and their predicted target genes were associated with cancer pathways. Serum and whole blood miRNA expression allowed discrimination between ES and control horses and merits further validation in a larger study cohort. The use of whole blood might be superior because it has higher miRNA content and is less influenced by pre‐analytical variables compared to serum. Concurrent dysregulation of single miRNAs in tissue and blood suggests a possible biological function of circulating miRNAs.     

Virulence gene regulation in pathogenic Escherichia coli.

The ability to regulate gene expression throughout the course of an infection is important for the survival of a pathogen in the host. Thus, virulence gene expression responds to environmental signals in many complex ways. Frequently, global regulatory factors associated with specific regulators co-ordinate expression of virulence genes. In this review, we present well-described regulatory mechanisms used to co-ordinate the expression of virulence factors by pathogenic Escherichia coli with a relative emphasis on diseases caused by E. coli in animals. Many of the virulence-associated genes of pathogenic E. coli respond to environmental conditions. The involvement of global regulators, including housekeeping regulons and virulence regulons, specific regulators and then sensor regulatory systems involved in virulence, is described. Specific regulation mechanisms are illustrated using the regulation of genes encoding for fimbriae, curli, haemolysin and capsules as examples.