蜜蜂非编码RNA研究进展

非编码RNA(Non-coding RNA,ncRNA)是指不编码蛋白质的功能性RNA的统称,主要包括微小RNA(MicroRNA,miRNA)、长链非编码RNA(Long non-coding RNA,lncRNA)和环状RNA(Circular RNA,circRNA)等,它们在各种生命活动中发挥着重要的调控作用.蜜蜂不仅是重要经济授粉昆虫,还是人类研究动物复杂社会行为的最佳模式生物.近年来,蜜蜂ncRNA亦是该领域研究热点,成果不断涌现,本文在介绍ncRNA的特征、分类及其主要作用机制的基础上,主要针对ncRNA在蜜蜂劳动分工、级型分化、繁殖性能和免疫防御等方面调控作用的最新研究进展进行综述,以期为深入探究ncRNA提供借鉴和参考.     

蜜蜂级型分化机理

蜜蜂Apis spp.能有效地为多种植物及农作物授粉, 具有重要的经济和生态价值; 蜜蜂作为高度真社会性昆虫, 已成为社会生物学研究的模式生物。社会性昆虫的生殖劳动分工具有重要的进化意义, 而级型分化是形成生殖劳动分工的基础。近年来, 关于蜜蜂级型分化的研究已取得诸多重要成果, 其机理也得到了较为深入的阐释。营养差异引发蜜蜂幼虫的级型分化。蜂王浆中的主要蛋白组分之一--Royalactin是诱导蜂王发育的关键营养因子, 而脂肪体细胞的表皮生长因子受体介导了Royalactin的这种蜂王诱导作用。DNA甲基化是重要的表观遗传机制之一, 且与个体发育和疾病发生紧密相关, 近来的研究表明DNA甲基化在蜜蜂级型分化过程中发挥重要的调控作用。此外, 越来越多的研究进一步深化了人们对内分泌系统调节级型分化作用的认识。本文从关键营养因子调控、 表观遗传调控和内分泌调节3方面综述蜜蜂级型分化的机理, 并对未来的研究提出可能的方向。     

蜜蜂卵巢激活研究进展

蜜蜂Apis作为典型的社会性昆虫,最重要的特征就是生殖劳动分工。卵巢激活是蜜蜂发挥生殖能力的重要影响因素。本文对蜜蜂卵巢激活的影响因素、蜜蜂卵巢激活相关的基因表达及microRNA在蜜蜂卵巢激活过程中的可能作用进行了介绍,为研究蜜蜂级型分化和生殖劳动分工的分子机制提供依据。     

熊蜂级型分化研究进展

熊蜂是众多野生植物及农作物的有效授粉昆虫,具有重要的经济和生态价值。熊蜂复杂的生长发育过程及社会性使其成为社会生物学研究的最佳模式生物之一。社会性昆虫的生殖劳动分工具有重要的进化意义,而级型分化是形成生殖劳动分工的基础。蜜蜂级型分化的研究已取得诸多重要成果,其机理也得到了较为深入的阐释,而熊蜂的社会性研究尚未形成系统,与蜜蜂研究相差甚远。近来的研究表明,饲喂频率或者饲喂总量的差异能够引起熊蜂级型分化的发生。保幼激素和蜕皮激素与熊蜂幼虫的发育紧密联系,在熊蜂级型分化的过程中发挥重要作用。一些参与蜜蜂级型分化的基因,在熊蜂级型间也存在差异表达。此外,群体间的相互作用以及蜂王和工蜂间的竞争也是促进熊蜂级型分化发生的重要因素。本文从营养、激素调控、群体发展及相互作用等方面综述熊蜂级型分化机制,并对未来的研究提出可能方向。     

蜜蜂级型分化机理

蜜蜂是整个大自然生态系统中不可或缺的一部分,能有效地为多种植物和农作物授粉。蜜蜂是典型的真社会性昆虫,其生殖劳动分工现象有重要进化意义。而级型分化是导致劳动分工的一个重要因素,蜜蜂级型分化现象的机理研究已成为目前重要的研究热点之一。本文对近年来蜜蜂级型分化机理方面的研究进展进行了综述。国内外很多学者从营养、激素、基因表达、蛋白质和表观遗传等方面对蜜蜂级型分化机理进行了研究。蜂王浆中富含的57 kDa、蜂王幼虫期充足的食物量以及蜂王幼虫期高滴度的保幼激素(JH)和蜕皮激素(MA)等都可促进蜂王卵巢的发育以及诱导蜂王表型产生;而工蜂浆中富含的双香豆酸可诱使工蜂表型的产生。近年研究表明,表皮生长因子受体(Egfr)、胰岛素受体底物基因(Irs)、雷帕霉素基因(Tor)和甲基转移酶3(Dnmt3)等基因均可影响蜂王和工蜂的分化;蛋白质表达谱分析表明,不同时间点的蜂王幼虫和工蜂幼虫表达的差异蛋白质很多;表观遗传分析表明,DNA甲基化、microRNAs以及组蛋白乙酰化均是导致蜂王和工蜂级型分化的因素。此外,发育空间和蜂王浆均可通过调控基因的DNA甲基化水平影响蜜蜂幼虫的级型分化。     

蜜蜂蜂王与工蜂级型分化研究进展

蜜蜂ApismekiferaL .是典型的社会性昆虫 ,蜂王和工蜂都是由受精卵发育而来的二倍体成蜂 ,但是在形态、生理、行为等方面有明显的差异 ,属于不同的级型。蜂王和工蜂的级型分化的关键时期发生在幼虫的 4龄末至 5龄止。分化是由分化基因调控的 ,幼虫期食物的质和量是分化的外部决定因子。JH对两级型中卵巢的分化有非常重要的调控作用。蜜蜂脑或其它组织中可能有分泌调控CA的咽侧体调节激素 ,它们通过对CA中JH的合成和分泌的调控而参与了分化的调控。章鱼胺等生物胺也参与了分化调控过程。     

蜜蜂——新兴的模式生物

蜜蜂作为具有重要经济价值和生态价值的社会性昆虫, 在诸如神经生物学和社会生物学等研究领域也具有很高的模型价值。蜜蜂基因组工程为深入认识蜜蜂的生物学特点,进一步发挥其在多个研究领域的模型价值奠定了分子基础。本文基于蜜蜂的生物学特点,介绍了蜜蜂作为模式生物所具备的优势,及其在学习和记忆、劳动分工、级型分化、免疫等热点领域的研究价值。通过总结和展望国内外蜜蜂生物学研究形势,呼吁国内相关各学科开展合作研究。     

ame-let-7调节蜜蜂劳动分工行为的研究进展

意大利蜜蜂是典型的社会性昆虫,存在与年龄相关的劳动分工行为,一直是人类研究动物行为的最佳模式生物。蜜蜂行为可塑性是劳动分工的重要特点,与其自身脑部神经结构变化、脑部基因表达变化及体内激素水平等有关。miRNAs与靶基因特异性结合,发挥多种生物调节功能。miR-let-7介导靶基因在动物发育及病理方面的研究较深,但对动物行为可塑性的调控机理尚未明确。本文就ame-let-7影响蜜蜂哺育蜂与采集蜂的劳动分工行为研究进行总结,主要从ame-let-7的表达模式、其对蜜蜂行为可塑性调节作用、对蜜蜂糖反应及学习记忆能力的影响及其相关靶基因的研究等方面进行归纳,为深入研究ame-let-7对蜜蜂行为可塑性的调控机制提供理论依据。     

MicroRNA在鱼类胚胎发育中的调控作用

MicroRNA(miRNA)是一类长度为21~23个核苷酸的调控性小分子RNA,它们通过抑制蛋白质翻译或降解mRNA的方式负调控基因表达,在胚胎发育、细胞凋亡、细胞增殖分化和肿瘤发生中发挥重要作用。近年来,越来越多的研究证实miRNA在鱼类胚胎发育过程中具有重要的调控作用。本文就近年来miRNA在鱼类胚胎发育中的作用研究作一综述,以期为进一步探索miRNA在鱼类生长发育、生理过程及疾病防御中的作用提供理论基础。     

昆虫microRNA的研究进展

MicroRNA (miRNA)是20世纪90年代发现的一类由内源基因编码的长度约21~24 nt的非编码单链RNA分子, 广泛存在于真核生物中, 对基因的转录后调控起着非常重要的作用。本文简要介绍了miRNA的产生与调控机制, 同时从昆虫miRNA的发现鉴定、 靶基因预测与功能验证, 昆虫miRNA的序列特征与进化, 果蝇和非果蝇类昆虫miRNA生物学功能以及供昆虫miRNA研究的网络平台等方面对昆虫miRNA的最新进展进行了综述, 旨在为进一步研究昆虫miRNA提供借鉴和参考。对昆虫miRNA的研究表明其参与调控细胞分化、 增殖及凋亡、 胚胎发育、 器官发生、 形态构建、 生理代谢、 环境协调、 行为认知、 免疫防御等几乎所有的生物过程。因此, 深入研究其生物功能、 调控网络和开发应用等可能成为今后一段时间昆虫miRNA研究的重要内容。     

Sucrose response thresholds of honey bee (Apis mellifera) foragers are not modulated by brood ester pheromone

Division of labor is a hallmark of eusocial insects and their ecological success can be attributed to it. Honey bee division of labor proceeds along a stereotypical ontogenetic path based on age, modulated by various internal and external stimuli. Brood pheromone is a major social pheromone of the honey bee that has been shown to affect honey bee division of labor. It elicits several physiological and behavioral responses; notably, regulating the timing of the switch from performing in-hive tasks to the initiation of foraging. Additionally, brood pheromone affects future foraging choice. In honey bees, sucrose response threshold is a physiological correlate of age of first foraging and foraging choice. Brood pheromone has been shown to modulate sucrose response threshold in young bees, but its effects on sucrose response thresholds of bees in advanced behavioral states (foragers) are not known. In this study we examined the sucrose response thresholds of two different task groups, foragers (pollen and non-pollen) and non-foraging bees, in response to honey bee brood pheromone. Sucrose response thresholds were not significantly different between brood pheromone treatment and controls among both non-pollen and pollen foragers. However, the sucrose response threshold of non-foraging bees was significantly higher in the brood pheromone treatment group than in the control group. The switch to foraging task is considered a terminal one, with honey bee lifespan being determined at least partially by risks and stress accompanying foraging. Our results indicate that foragers are physiologically resistant to brood pheromone priming of sucrose response thresholds.     

The microRNA ame-miR-279a regulates sucrose responsiveness of forager honey bees (Apis mellifera)

Increasing evidence demonstrates that microRNAs (miRNA) play an important role in the regulation of animal behaviours. Honey bees (Apis mellifera) are eusocial insects, with honey bee workers displaying age-dependent behavioural maturation. Many different miRNAs have been implicated in the change of behaviours in honey bees and ame-miR-279a was previously shown to be more highly expressed in nurse bee heads than in those of foragers. However, it was not clear whether this difference in expression was associated with age or task performance. Here we show that ame-miR-279a shows significantly higher expression in the brains of nurse bees relative to forager bees regardless of their ages, and that ame-miR-279a is primarily localized in the Kenyon cells of the mushroom body in both foragers and nurses. Overexpression of ame-miR-279a attenuates the sucrose responsiveness of foragers, while its absence enhances their sucrose responsiveness. Lastly, we determined that ame-miR-279a directly target the mRNA of Mblk-1. These findings suggest that ame-miR-279a plays important roles in regulating honey bee division of labour.     

Caste-specific gene expression in the stingless bee <Emphasis Type="Italic">Melipona quadrifasciata</Emphasis> – Are there common patterns in highly eusocial bees?

Summary. Caste polyphenism is a multifaceted phenomenon, most evident in the marked differences in reproductive capacity and longevity between queens and workers. The mechanisms underlying caste differentiation and division of labor are mainly addressed in the honey bee, and recently have been studied at the molecular level. Yet, generalizations drawn from studies on this model organism require validation by comparative studies. We choose Melipona quadrifasciata, a sister-group species to honey bees, to investigate differences in gene expression between newly emerged adult queens and workers. RNA extracts were subjected to a differential display protocol (DDRT-PCR). The putative differentially expressed genes, for which annotation was available, were validated by RT-PCR and hybridization. Differential expression was observed for myosin, projectin, kettin, cytochrome P450, Rab11 and Sas10. Except for kettin, all of these were overexpressed in the worker caste. Projectin and kettin could play roles in caste-specific flight muscle organization. The putative Rab11 and Sas10 homolog genes could be involved in fertility-related cell signaling and in longevity-related gene silencing, respectively. Cytochrome P450 overexpression in Melipona workers corroborates similar findings in the honey bee, thus indicating a common function in the social insect caste syndrome.Received 9 January 2003; revised 10 March 2004; accepted 2 April 2004.     

period expression in the honey bee brain is developmentally regulated and not affected by light, flight experience, or colony type

Changes in circadian rhythms of behavior are related to age-based division of labor in honey bee colonies. The expression of the clock gene period (per) in the bee brain is associated with age-related changes in circadian rhythms of behavior, but previous efforts to firmly associate per brain expression with division of labor or age have produced variable results. We explored whether this variability was due to differences in light and flight experience, which vary with division of labor, or differences in colony environment, which are known to affect honey bee behavioral development. Our results support the hypothesis that per mRNA expression in the bee brain is developmentally regulated. One-day-old bees had the lowest levels of expression and rarely showed evidence of diurnal fluctuation, while foragers and forager-age bees (> 21 days of age) always had high levels of brain per and strong and consistent diurnal patterns. Results from laboratory and field experiments do not support the hypothesis that light, flight experience, and colony type influence per expression. Our results suggest that the rate of developmental elevation in per expression is influenced by factors other than the ones studied in our experiments, and that young bees are more sensitive to these factors than foragers.     

Division of Labor Associated with Brood Rearing in the Honey Bee: How Does It Translate to Colony Fitness?

Division of labor is a striking feature observed in honey bees and many other social insects. Division of labor has been claimed to benefit fitness. In honey bees, the adult work force may be viewed as divided between non-foraging hive bees that rear brood and maintain the nest, and foragers that collect food outside the nest. Honey bee brood pheromone is a larval pheromone that serves as an excellent empirical tool to manipulate foraging behaviors and thus division of labor in the honey bee. Here we use two different doses of brood pheromone to alter the foraging stimulus environment, thus changing demographics of colony division of labor, to demonstrate how division of labor associated with brood rearing affects colony growth rate. We examine the effects of these different doses of brood pheromone on individual foraging ontogeny and specialization, colony level foraging behavior, and individual glandular protein synthesis. Low brood pheromone treatment colonies exhibited significantly higher foraging population, decreased age of first foraging and greater foraging effort, resulting in greater colony growth compared to other treatments. This study demonstrates how division of labor associated with brood rearing affects honey bee colony growth rate, a token of fitness.     

Molecular underpinnings of the early brain developmental response to differential feeding in the honey bee Apis mellifera

Brain differential morphogenesis in females is one of the major phenotypic manifestations of caste development in honey bees. Brain diphenism appears at the fourth larval phase as a result of the differential feeding regime developing females are submitted during early phases of larval development. Here, we used a forward genetics approach to test the early brain molecular response to differential feeding leading to the brain diphenism observed at later developmental phases. Using RNA sequencing analysis, we identified 53 differentially expressed genes (DEGs) between the brains of queens and workers at the third larval phase. Since miRNAs have been suggested to play a role in caste differentiation after horizontal and vertical transmission, we tested their potential participation in regulating the DEGs. The miRNA-mRNA interaction network, including the DEGs and the royal- and worker-jelly enriched miRNA populations, revealed a subset of miRNAs potentially involved in regulating the expression of DEGs. The interaction of miR-34, miR-210, and miR-317 with Takeout, Neurotrophin-1, Forked, and Masquerade genes was experimentally confirmed using a luciferase reporter system. Taken together, our results reconstruct the regulatory network that governs the development of the early brain diphenism in honey bees.     

Methionine as a methyl donor regulates caste differentiation in the European honey bee (Apis mellifera)

Nutrition contributes to honey bee caste differentiation, but the role of individual nutrients is still unclear. Most essential amino acid contents, except that of methionine (Met), are greater in royal jelly than worker jelly. After ∼3.5 d, the Met content in the latter was slightly greater than in the former. Met is the major raw material used in the synthesis of S-adenosyl-L-methionine, an active methyl donor for DNA methylation, which is an epigenetic driver of caste differentiation. Here, we tested whether Met regulates caste differentiation in honey bees by determining its effects on the caste development of bees receiving four diets: the basic, basic + 0.2% Met, basic + 0.2% Met + 20 mg/kg 5-azacytidine, and basic + 20 mg/kg 5-azacytidine. The presence of Met decreased the adult bee body length and the numbers of ovarioles, indicating that Met may direct the development of female larvae toward worker bees. The upregulated expression of SAMS, Dnmt1, and Dnmt3 caused by Met exposure in 4-d-old larvae indicated that the worker-inductive effects of Met may occur through the promotion of DNA methylation. We investigated the co-effects of Met and glucose on bee development, and found that the effects of an increased glucose level on the number of ovarioles and body length did not strengthen the worker-inductive effects caused by Met. Our results contribute to caste development theory and suggest that Met—as a methyl donor—plays a regulatory, but not decisive, role in caste differentiation.