共生表皮葡萄球菌促进果蝇胚后发育

【背景】动物体定殖有多种共生微生物,这些共生微生物严重影响着宿主生理和病理,日益成为研究热点之一。【目的】分离与鉴定黑腹果蝇共生菌,探究表皮葡萄球菌对黑腹果蝇的发育影响和潜在作用机制。【方法】用CEM培养基(Carotenoid expression medium)从果蝇肠道内分离细菌,通过16SrRNA基因序列比对鉴定菌株;以发育时间和幼虫表面积检测果蝇的发育时期和生长速率;利用实时定量PCR检测果蝇促前胸腺激素与胰岛素通路的激活。【结果】从果蝇体内分离到的菌株为表皮葡萄球菌,该菌可以有效定殖于果蝇的肠道。表皮葡萄球菌通过提高果蝇生长速率而显著促进其发育。在分子水平上,表皮葡萄球菌激活PTTH和胰岛素信号以刺激宿主的生长发育。【结论】表皮葡萄球菌是果蝇的一种共生菌,可以通过调控PTTH和胰岛素信号而刺激果蝇生长发育。     

家蚕蜕皮与变态的内分泌调控

家蚕的蜕皮与变态是由前胸腺分泌的脱皮素（ｍｏｌｔｉｎｇ ｈｏｒｍｏｎｅ或 ｅｃｄｙｓｔｅｒｏｉｄ简称 ＭＨ）及由咽侧体分泌的保幼激素（ｊｕｖｅｎｉｌｅ ｈｏｒｍｏｎｅ）控制的,而促有前胸腺激素（ｐｒｏｔｈｏｒａｃｉｃｏｔｒｏｐｉｃ ｈｏｒｍｏｎｅ,以下简称ＰＴＴＨ）的功能为刺激前胸腺分泌蜕皮素。笔者近１０年来从家蚕内分泌体系的一系列研究中发现,蜕皮素浓度的变化可以通过控制咽侧体的保幼激素的生物合成来影响幼虫发育,而ＰＴＴＨ的信息传递可通过调控前胸腺的功能,进而影响血淋巴中蜕皮素浓度。     

C-型咽侧体抑制素(AST-C)和促前胸腺激素释放激素(PTTH)基因在家蚕脑组织中的时空表达分析

【目的】咽侧体抑制素在昆虫体内具有重要的调控功能。本研究比较了家蚕Bombyx mori C-型咽侧体抑制素(allatostatin C,AST-C)与促前胸腺激素释放激素(prothoracicotropic hormone,PTTH)基因在不同发育阶段家蚕脑组织中转录表达的模式及其在脑组织的表达定位,以期为家蚕AST-C的功能研究提供重要的线索。【方法】利用脑组织芯片数据分析比较AST-C和PTTH基因在家蚕脑组织中的发育表达特征,RT-PCR验证其芯片数据,分析AST-C在不同发育阶段家蚕中枢神经系统中的表达模式,并用全组织包埋原位杂交技术对AST-C和PTTH在脑组织的表达进行定位。【结果】AST-C和PTTH在不同发育阶段家蚕脑组织中有相似的转录表达模式,且都在脑组织外侧一对神经分泌细胞中表达。【结论】AST-C可能与PTTH以相同的转录表达模式共同参与家蚕的变态发育调控。     

昆虫激素和抗激素类在蚕业上的应用研究进展

控制家蚕幼虫蜕变和变态的内分泌系统是脑一咽侧体一前胸腺。咽侧体分泌的保幼激素（JH）和前胸腺分泌的蜕皮激素（MH）调节着家蚕的幼虫蜕皮、变态等生命现象,而脑分泌的促咽侧体激素和促前胸腺激素又控制着这两种腺体的分泌活动。家蚕的MH和JH的化学结构早在60年代中期被先后阐明,70年代后对这两种主要激素在血淋巴中的浓度已能精确定量,从而阐明了发生幼虫蜕皮和变态的激素环境。与此同时,发现了一些天然化合物能影响家蚕正常的内分泌活动,导致早熟变态和其他生理变化（如体色变化、生有障碍等）,称之为抗激素类物质。家蚕内分…     

Insect ecdysteroids biosynthesis and its regulation by neuropeptides

蜕皮激素是对节肢动物体内类固醇激素的统称,昆虫的蜕皮激素主要由内分泌器官前胸腺合成,具有诱发幼虫周期性蜕皮以及最终变态蜕皮的生理功能.近期的研究工作阐明了前胸腺中原先被称为“黑箱”的一系列酶促反应步骤,此外促前胸腺激素受体的成功鉴定使人们对PTTH信号转导通路调控前胸腺蜕皮激素合成有了更深入的理解.     

昆虫蜕皮激素生物合成及其神经肽调控

蜕皮激素是对节肢动物体内类固醇激素的统称,昆虫的蜕皮激素主要由内分泌器官前胸腺合成,具有诱发幼虫周期性蜕皮以及最终变态蜕皮的生理功能。近期的研究工作阐明了前胸腺中原先被称为"黑箱"的一系列酶促反应步骤,此外促前胸腺激素受体的成功鉴定使人们对PTTH信号转导通路调控前胸腺蜕皮激素合成有了更深入的理解。     

共生大肠杆菌促进黑腹果蝇生长发育

【背景】共生菌对宿主的很多生理功能有着重要影响,但微生物菌群的多样性和复杂性使得探索其潜在的机制存在困难。黑腹果蝇的无菌和悉菌模型可以被用来研究细菌和宿主的相互作用。【目的】分离和鉴定果蝇肠道大肠杆菌,并研究其对宿主生长发育的影响。【方法】利用大肠杆菌选择性培养基分离果蝇肠道大肠杆菌,通过16S rRNA基因序列比对鉴定菌株。利用体外和体内定殖实验验证共生关系。通过果蝇的发育历期和生长速率实验检测该细菌对宿主生长发育的影响。利用RT-qPCR技术对促胸腺激素及胰岛素信号通路相关基因的表达水平进行检测。【结果】从实验室饲养和野生果蝇肠道体内分离并鉴定得到大肠杆菌。体内和体外定殖试验中大肠杆菌可以和果蝇肠道共生菌共存,说明大肠杆菌是果蝇肠道共生菌。另外,大肠杆菌通过提高果蝇生长速率促进其发育。在分子水平上,大肠杆菌可以激活果蝇体内脑促胸腺激素和胰岛素信号通路相关基因的表达。【结论】大肠杆菌是果蝇肠道共生菌并能促进果蝇生长发育。     

共生大肠杆菌促进黑腹果蝇生长发育（英文）

【背景】共生菌对宿主的很多生理功能有着重要影响,但微生物菌群的多样性和复杂性使得探索其潜在的机制存在困难。黑腹果蝇的无菌和悉菌模型可以被用来研究细菌和宿主的相互作用。【目的】分离和鉴定果蝇肠道大肠杆菌,并研究其对宿主生长发育的影响。【方法】利用大肠杆菌选择性培养基分离果蝇肠道大肠杆菌,通过16S rRNA基因序列比对鉴定菌株。利用体外和体内定殖实验验证共生关系。通过果蝇的发育历期和生长速率实验检测该细菌对宿主生长发育的影响。利用RT-qPCR技术对促胸腺激素及胰岛素信号通路相关基因的表达水平进行检测。【结果】从实验室饲养和野生果蝇肠道体内分离并鉴定得到大肠杆菌。体内和体外定殖试验中大肠杆菌可以和果蝇肠道共生菌共存,说明大肠杆菌是果蝇肠道共生菌。另外,大肠杆菌通过提高果蝇生长速率促进其发育。在分子水平上,大肠杆菌可以激活果蝇体内脑促胸腺激素和胰岛素信号通路相关基因的表达。【结论】大肠杆菌是果蝇肠道共生菌并能促进果蝇生长发育。     

共生乳酸乳球菌加速黑腹果蝇发育（英文）

为了从果蝇肠道内分离乳酸乳球菌,并研究它对宿主发育历期的影响,用MRS培养基从果蝇肠道内分离细菌,并经16S rRNA基因序列比对确定菌种;随后,检测果蝇的发育历期和生长速率。其中,免疫荧光染色和实时定量PCR分别用于检测肠道细胞增殖和促胸腺激素与胰岛素通路的激活;葡萄糖氧化酶法用于检测葡萄糖浓度。结果显示,从果蝇体内分离到一株乳酸乳球菌,该菌可以在果蝇肠道内有效定植,并通过生长速率促进果蝇的发育历期。在细胞水平上,乳酸乳球菌相关果蝇肠道内有丝分裂细胞约是无菌果蝇的6倍。在分子水平上,乳酸乳球菌激活荷尔蒙和胰岛素信号以刺激机体全身性增长。综上所述,乳酸乳球菌是果蝇的共生菌,可以通过荷尔蒙和胰岛素信号刺激果蝇的生长和发育。     

植物乳杆菌促进黑腹果蝇生长发育

【目的】检测乳酸菌对果蝇发育历期的影响,进一步探讨其对果蝇促生长的分子机制。【方法】利用选择性培养基MRS从黑腹果蝇Drosophila melanogaster体内分离乳酸菌,利用革兰氏染色、生化方法及16S rRNA基因进行鉴定;通过体内定植和世代传递实验验证该菌是黑腹果蝇的共生菌;采用悉生模型检测乳酸菌对黑腹果蝇发育的促生长作用;利用实时定量PCR技术检测黑腹果蝇体内促前胸腺激素基因PTTH和胰岛素通路相关基因InR的表达水平;利用葡萄糖试剂盒检测血淋巴液葡萄糖浓度。【结果】从黑腹果蝇中分离到的菌株鉴定为植物乳杆菌Lactobacillus plantarum FY1菌株(Gen Bank登录号:KY038178),可在黑腹果蝇肠道内定植,每个肠道定植量约为104CFU,并能在世代间稳定传递。FY1菌株体外发酵可降低p H值至5.2,可诱导无菌果蝇卵至蛹发育时间由20.0 d缩短至6.9 d,卵至成虫发育时间由30.0 d缩短至10.7 d,其生长速率是无菌果蝇的约2倍。实时定量PCR结果表明,FY1菌株显著地提前了PTTH表达高峰期,同时降低果蝇中InR表达水平,血淋巴液葡萄糖浓度从5.1 mg/mL降低至2.7 mg/mL。【结论】植物乳杆菌是黑腹果蝇的一种益生菌,推测能通过胰岛素信号通路促进宿主黑腹果蝇的生长和发育。     

The soma-germline communication: implications for somatic and reproductive aging

Aging is characterized by a functional decline in most physiological processes, including alterations in cellular metabolism and defense mechanisms. Increasing evidence suggests that caloric restriction extends longevity and retards age-related diseases at least in part by reducing metabolic rate and oxidative stress in a variety of species, including yeast, worms, flies, and mice. Moreover, recent studies in invertebrates – worms and flies, highlight the intricate interrelation between reproductive longevity and somatic aging (known as disposable soma theory of aging), which appears to be conserved in vertebrates. This review is specifically focused on how the reproductive system modulates somatic aging and vice versa in genetic model systems. Since many signaling pathways governing the aging process are evolutionarily conserved, similar mechanisms may be involved in controlling soma and reproductive aging in vertebrates.     

Ageing and the regulation of protein synthesis: a balancing act?

Ageing in diverse species ranging from yeast to humans is associated with extensive changes in both general and specific protein synthesis. Accumulating evidence now indicates that these alterations are not simply a corollary of the ageing process but, rather, they have a causative role in senescent decline. Indeed, interfering with mRNA translation significantly influences longevity. Interestingly, the mechanisms that control mRNA translation interface with intricate, conserved signalling pathways and specific conditions that regulate ageing, such as the insulin-insulin growth factor 1 signalling pathway and caloric restriction. This emerging relationship reveals that protein synthesis is a novel determinant of ageing in diverse organisms such as yeast, worms, flies and mice and can thus be considered as a universal component of the ageing process.     

Role of the growth hormone-insulin-like growth factor-1-insulin system signaling in aging and longevity: evolutional aspect

Growth hormone (GH)/ insulin-like growth factor 1 (IGF-1)/ insulin signaling molecules linked to longevity include DAF-2 and insulin-receptor and their homologues in mammals, and to inactivation of corresponding genes followed by increased life span in nematodes, fruit flies, and mice. It is possible that the life-prolonging effect of calorie restriction is due to decreasing IGF-1 levels. A search of pharmacological modulators of life-span-extending mutations in the GH/IGF-1/insulin signaling pathway and mimetic effects of caloric restriction is a priority directions in the regulation of longevity. Some literature and our own observations suggest that antidiabetic drugs could be promising candidates for both life span extension and prevention of cancer.     

Deletion of the mammalian INDY homolog mimics aspects of dietary restriction and protects against adiposity and insulin resistance in mice

Reduced expression of the Indy (I'm Not Dead, Yet) gene in D.?melanogaster and its homolog in C.?elegans prolongs life span and in D.?melanogaster augments mitochondrial biogenesis in a manner akin to caloric restriction. However, the cellular mechanism by which Indy does this is unknown. Here, we report on the knockout mouse model of the mammalian Indy (mIndy) homolog, SLC13A5. Deletion of mIndy in mice (mINDY(-/-) mice) reduces hepatocellular ATP/ADP ratio, activates hepatic AMPK, induces PGC-1α, inhibits ACC-2, and reduces SREBP-1c levels. This signaling network promotes hepatic mitochondrial biogenesis, lipid oxidation, and energy expenditure and attenuates hepatic de novo lipogenesis. Together, these traits protect mINDY(-/-) mice from the adiposity and insulin resistance that evolve with high-fat feeding and aging. Our studies demonstrate a profound effect of mIndy on mammalian energy metabolism and suggest that mINDY might be a therapeutic target for the treatment of obesity and type 2 diabetes.     

Triggering signaling cascades by receptor tyrosine kinases.

Growth factor receptors that are tyrosine kinases (RTKs) regulate growth and differentiation of cells in many organisms, including flies, worms, frogs, mice and humans. There has been recent progress in understanding the mechanism by which these receptors transduce signals. Worm and insect studies on RTKs have relied primarily on genetics, while the mammalian studies have employed a combination of molecular genetics and biochemistry. While many RTKs seem to have unique features, there are also many general signal transduction principles that emerge from these studies. In this review, we will focus on common signaling molecules, using RTKs from both vertebrates and invertebrates as examples.     

Identification of a novel prothoracicostatic hormone and its receptor in the silkworm Bombyx mori

The insect brain regulates the activity of the prothoracic glands to secrete ecdysteroids, which affect growth, molting, and metamorphosis. Here we report the identification of a novel prothoracicostatic factor and its receptor in the silkworm Bombyx mori. The prothoracicostatic factor purified from pupal brains of B. mori is a decapeptide with the conserved structure of an insect myosuppressin and thus named Bommo-myosuppressin. Bommo-myosuppressin dose dependently suppressed the cAMP level and inhibited ecdysteroidogenesis in the larval prothoracic glands at much lower concentrations than the prothoracicostatic peptide, the other prothoracicostatic factor reported previously. In vitro analyses using a prothoracic gland incubation method revealed that Bommo-myosuppressin and prothoracicostatic peptide regulate the prothoracic gland activity via different receptors. In situ hybridization and immunohistochemistry revealed the existence of Bommo-myosuppressin in the brain neurosecretory cells projecting to neurohemal organs in which it is stored. We also identified and functionally characterized a specific receptor for Bommo-myosuppressin and showed its high expression in the prothoracic glands. All these results suggest that Bommo-myosuppressin functions as a prothoracicostatic hormone and plays an important role in controlling insect development.     

Autophagy in neuronal cell loss: a road to death

The regulation of ageing has been extensively studied in divergent animal model systems including worms, flies and mice. However, little is known about the cellular pathways that mediate the death of these organisms. Analysing major cellular changes in the ageing nematode Caenorhabditis elegans has revealed a gradual, progressive deterioration of different tissues except for the nervous system, which remarkably preserves its integrity even in advanced old age. In addition, genetic data have shown that, in C. elegans and in the fruit fly Drosophila melanogaster, lifespan is controlled by signals derived from neurons and acting throughout adulthood. Organismal death thus seems to be a consequence of the decline of specific neurons. Accumulating evidence demonstrates that late onset of neuronal cell loss generally occurs via autophagy, a process in which eukaryotic cells self-digest parts of their contents during development or to survive starvation. Here we suggest that overactivation of autophagy in the cells of the nervous system is the eventual cause of "physiological" death.     

Dietary composition specifies consumption, obesity, and lifespan in Drosophila melanogaster

The inability to properly balance energy intake and expenditure with nutrient supply forms the basis for some of today's most pressing health issues, including diabetes and obesity. Mechanisms of nutrient homeostasis may also lie at the root of dietary restriction, a manipulation whereby reduced nutrient availability extends lifespan and ameliorates age-related deteriorations in many species. The traditional belief that the most important aspect of the diet is its energetic (i.e. caloric) content is currently under scrutiny. Hypotheses that focus on diet composition and highlight more subtle characteristics are beginning to emerge. Using Drosophila melanogaster , we asked whether diet composition alone, independent of its caloric content, was sufficient to impact behavior, physiology, and lifespan. We found that providing flies with a yeast-rich diet produced lean, reproductively competent animals with reduced feeding rates. Excess dietary sugar, on the other hand, promoted obesity, which was magnified during aging. Addition of dietary yeast often limited or reversed the phenotypic changes associated with increased dietary sugar and vice versa, and dietary imbalance was associated with reduced lifespan. Our data reveal that diet composition, alone and in combination with overall caloric intake, modulates lifespan, consumption, and fat deposition in flies, and they provide a useful foundation for dissecting the underlying genetic mechanisms that link specific nutrients with important aspects of general health and longevity.     

Development of diet-induced insulin resistance in adult Drosophila melanogaster

The fruit fly Drosophila melanogaster is increasingly utilized as an alternative to costly rodent models to study human diseases. Fly models exist for a wide variety of human conditions, such as Alzheimer's and Parkinson's Disease, or cardiac function. Advantages of the fly system are its rapid generation time and its low cost. However, the greatest strength of the fly system are the powerful genetic tools that allow for rapid dissection of molecular disease mechanisms. Here, we describe the diet-dependent development of metabolic phenotypes in adult fruit flies. Depending on the specific type of nutrient, as well as its relative quantity in the diet, flies show weight gain and changes in the levels of storage macromolecules. Furthermore, the activity of insulin-signaling in the major metabolic organ of the fly, the fat body, decreases upon overfeeding. This decrease in insulin-signaling activity in overfed flies is moreover observed when flies are challenged with an acute food stimulus, suggesting that overfeeding leads to insulin resistance. Similar changes were observed in aging flies, with the development of the insulin resistance-like phenotype beginning at early middle ages. Taken together, these data demonstrate that imbalanced diet disrupts metabolic homeostasis in adult D. melanogaster and promotes insulin-resistant phenotypes. Therefore, the fly system may be a useful alternative tool in the investigation of molecular mechanisms of insulin resistance and the development of pharmacologic treatment options.