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。     

LncRNA在蜜蜂级型分化中的功能研究

蜜蜂的级型分化被证实是由蜂王浆中的Royalactin决定,工蜂和蜂王幼虫在级型分化时编码基因的表达差异也被广泛研究.我们发现,在蜜蜂幼虫的级型分化过程中,lncRNA也有着显著的表达差异,因此认为,lncRNA也参与了蜜蜂的级型分化过程.进一步的分析显示,lncRNA可能通过影响上下游基因的转录和功能执行的方式,在蜜蜂早期发育的多细胞组织发育、神经系统发育和转录调控的过程中起到重要的调控作用.     

蜜蜂级型分化相关生理因子研究进展

蜜蜂Apis melliferaL.是典型的社会性昆虫,蜂群内蜂王和工蜂的级型分化现象吸引了众多研究者的高度关注。蜜蜂级型分化是一个极为复杂的生长发育调节过程,许多重要生理因子参与其中,包括保幼激素、蜕皮激素、胰岛素/胰岛素类似物信号通路等。本文概述了蜜蜂级型分化相关生理因子研究进展:保幼激素决定着蜜蜂级型发育的轨迹并能阻止卵巢发育过程中细胞的程序性死亡;蜕皮激素协同保幼激素发挥调节作用;蜜蜂蜂王与工蜂的躯体大小及相关器官大小的级型特异性差异与胰岛素/胰岛素类似物信号通路密切相关。此外,本文还介绍了蜜蜂级型分化模型,该模型系统描述了上述各生理因子对级型分化的综合作用。     

少突胶质细胞发育分化的表观遗传学调控研究进展

少突胶质细胞的发育分化是由遗传的和后生的机制共同参与调控的一系列动态过程,其中,对于后生调控机制的研究称为表观遗传学。既往对少突胶质细胞的研究主要集中在相关基因本身的特性研究。近年来,关于寻址组蛋白修饰的研究使我们对少突胶质细胞发育和衰老过程中基因表达的后生调控有了新的认识。这些理论将有助于我们更好地理解脱髓鞘及衰老后髓鞘修复障碍的原因和防治途径。     

蜜蜂microRNA的研究进展

MicroRNA (miRNA)是一类长度为18~24 nt的内源性非编码小RNA分子,它能通过与靶标mRNA 分子互补结合抑制蛋白质翻译或导致 mRNA 降解,从而调控靶基因表达。蜜蜂是重要的社会性经济昆虫,一直是国际上热门的研究对象。迄今为止,通过各种生物技术在蜜蜂中发现已鉴定注册的miRNA共有218个,对蜜蜂miRNA的研究表明其在蜜蜂的胚胎发育、级型分化、劳动分工和免疫防御等方面可能具有重要的调控作用。本文就miRNA对蜜蜂蜂王和工蜂级型分化、哺育蜂和采集蜂劳动分工、舞蹈行为、脑部神经功能及免疫防御等方面调控作用的最新研究进展进行了综述,以期为进一步研究miRNA提供借鉴和参考。     

中华蜜蜂种群遗传分化与环境适应机制研究进展

中华蜜蜂Apis cerana cerana是我国十分关键和重要的传粉媒介昆虫,在不同栖息地中广泛分布,表现出飞行敏捷、采蜜期长和适应性强等优点。但近些年中华蜜蜂正面临前所未有的种群多样性下降,为保护这些特定的中华蜜蜂种群的遗传资源,研究人员基于几何形态学、分子生物学和基因组学等技术手段对中华蜜蜂遗传分化和环境适应机制进行了研究,而在我国这些多样化的中华蜜蜂种群为揭示其种群适应性进化规律提供了绝佳材料。本文从中华蜜蜂种群遗传分化与环境变化的相关性、形态变异与环境适应、环境适应性生理和行为改变及这些表型变化的遗传机制4个方面综述了相关研究进展。研究发现,物理屏障和生态环境的变化,特别是海拔和纬度相关环境变化是造成中华蜜蜂种群分化的主要原因。气候因子中,温度、氧气、辐射和湿度等对中华蜜蜂环境适应性的形态发育和生理生态特征产生重要影响。形态特征的变化主要体现在体型大小和体色上,代谢生理和行为改变是其环境适应的重要策略。基于现代基因组学和分子生物学技术的种群遗传学和种群基因组学研究发现,与社会分工行为、学习感知行为、信息感知、生长发育、温度适应和代谢等相关的基因或通路受到自然选择作用,这为中华...     

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。     

肝纤维化的表观遗传学研究进展

肝纤维化是常见的慢性进行性肝病,是慢性肝病发展到肝硬化阶段的必经阶段,却有逆转的可能性。肝纤维化的中心环节是肝星状细胞的激活。关于肝星状细胞的激活,除了经典的肝纤维化通路,不断有新的通路和机制出现,包括自噬、内质网应激、氧化应激、胆固醇代谢和表观遗传,这些都揭示了肝星状细胞的活化机制。表观遗传包括DNA甲基化、组蛋白修饰和调节性非编码RNAs,这些机制也参与调节肝星状细胞活化和肝纤维化发生,对表观遗传和肝纤维化治疗之间的关系研究具有重要意义。     

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.     

蜜蜂肠道菌群的培养方法及特性研究进展

肠道菌群在蜜蜂的消化、营养和抗病性等方面发挥了很多潜在的益生作用。为了加深对以蜜蜂为主的传粉昆虫肠道菌群的了解,本文综述了蜜蜂肠道菌群的人工厌氧培养方法及特性,重点综述了Snodgrassella属、Gilliamella属、Frischella属、Lactobacillus属、Bifidobacterium属和Alpha-1,Alpha-2厌氧细菌类群。旨在通过特定的培养方法获取纯培养的细菌,以供进一步研究特定肠道菌群与特定功能的直接联系。希望这些培养技术能帮助大家提升对蜜蜂肠道共生菌在蜜蜂营养和健康方面所起的作用有所了解。     

Differential expression of odorant-binding proteins in the mandibular glands of the honey bee according to caste and age

Odorant-binding proteins (OBPs) and chemosensory proteins (CSPs) mediate both perception and release of chemical stimuli in insects. The genome of the honey bee contains 21 genes encoding OBPs and 6 encoding CSPs. Using a proteomic approach, we have investigated the expression of OBPs and CSPs in the mandibular glands of adult honey bees in relation to caste and age. OBP13 is mostly expressed in young individuals and in virgin queens, while OBP21 is abundant in older bees and is prevalent in mated queens. OBP14, which had been found in larvae, is produced in hive workers' glands. Quite unexpectedly, the mandibular glands of drones also contain OBPs, mainly OBP18 and OBP21. We have expressed three of the most represented OBPs and studied their binding properties. OBP13 binds with good specificity oleic acid and some structurally related compounds, OBP14 is better tuned to monoterpenoid structures, while OBP21 binds the main components of queen mandibular pheromone as well as farnesol, a compound used as a trail pheromone in the honey bee and other hymenopterans. The high expression of different OBPs in the mandibular glands suggests that such proteins could be involved in solubilization and release of semiochemicals.     

蜜蜂寄生螨—狄斯瓦螨的研究进展

狄斯瓦螨Varroa destructor是对世界养蜂业危害最大的蜜蜂寄生虫,严重危害蜜蜂封盖幼虫、蛹和成蜂,并携带和传播蜜蜂病毒,造成蜂群生产力严重下降乃至全群毁灭。狄斯瓦螨的有效防治措施的研发有赖于对其研究进展的了解,本文综述了以下3方面的研究概况:1)狄斯瓦螨的繁殖特性;2)对蜜蜂的危害;3)主要防治方法。以期为蜂螨相关的研究和应用奠定基础。     

Mitochondrial structure and dynamics as critical factors in honey bee (Apis mellifera L.) caste development

The relationship between nutrition and phenotype is an especially challenging question in cases of facultative polyphenism, like the castes of social insects. In the honey bee, Apis mellifera, unexpected modifications in conserved signaling pathways revealed the hypoxia response as a possible mechanism underlying the regulation of body size and organ growth. Hence, the current study was designed to investigate possible causes of why the three hypoxia core genes are overexpressed in worker larvae. Parting from the hypothesis that this has an endogenous cause and is not due to differences in external oxygen levels we investigated mitochondrial numbers and distribution, as well as mitochondrial oxygen consumption rates in fat body cells of queen and worker larvae during the caste fate-critical larval stages. By immunofluorescence and electron microscopy we found higher densities of mitochondria in queen larval fat body, a finding further confirmed by a citrate synthase assay quantifying mitochondrial functional units. Oxygen consumption measurements by high-resolution respirometry revealed that queen larvae have higher maximum capacities of ATP production at lower physiological demand. Finally, the expression analysis of mitogenesis-related factors showed that the honey bee TFB1 and TFB2 homologs, and a nutritional regulator, ERR, are overexpressed in queen larvae. These results are strong evidence that the differential nutrition of queen and worker larvae by nurse bees affects mitochondrial dynamics and functionality in the fat body of these larvae, hence explaining their differential hypoxia response.     

Multiple virus infections in the honey bee and genome divergence of honey bee viruses

Using uniplex RT-PCR we screened honey bee colonies for the presence of several bee viruses, including black queen cell virus (BQCV), deformed wing virus (DWV), Kashmir bee virus (KBV), and sacbrood virus (SBV), and described the detection of mixed virus infections in bees from these colonies. We report for the first time that individual bees can harbor four viruses simultaneously. We also developed a multiplex RT-PCR assay for the simultaneous detection of multiple bee viruses. The feasibility and specificity of the multiplex RT-PCR assay suggests that this assay is an effective tool for simultaneous examination of mixed virus infections in bee colonies and would be useful for the diagnosis and surveillance of honey bee viral diseases in the field and laboratory. Phylogenetic analysis of putative helicase and RNA-dependent RNA polymerase (RdRp) encoded by viruses reveal that DWV and SBV fall into a same clade, whereas KBV and BQCV belong to a distinct lineage with other picorna-like viruses that infect plants, insects and vertebrates. Results from field surveys of these viruses indicate that mixed infections of BQCV, DWV, KBV, and SBV in the honey bee probably arise due to broad geographic distribution of viruses.