Uncovering the functional basis of the reversal of the fecundity/longevity trade-off in a termite

生育能力/寿命权衡的反转随着社会性独立地演化了几次。这为社会性、繁殖力和寿命在进化过程中相互影响的假设提供了强有力的支持。我们从第一个资助阶段的分子结果表明，在途径水平上的趋同进化。对于所有被研究的物种，我们确定了TOR(雷帕霉素的靶标)/IIS(胰岛素/胰岛素样生长因子1信号)-保幼激素(JH)轴上的种姓特定的、与年龄相关的网络变化，该网络影响与寿命和繁殖力相关的途径(TOR/IIS-JH-LIFE网络的TOR/IIS-JH-寿命生殖力)。然而，细节似乎在不同物种之间有所不同。此外，我们在白蚁身上发现了与年龄相关的转座元件(TE)活性的强烈信号，而我们在社会性膜翅目中没有检测到这一信号。长期以来，人们一直假设这些“跳跃基因”在动物衰老过程中起作用，最近证实了两者之间的因果联系。在第二个资助阶段，我们的目标是通过在白蚁身上进行功能实验来更详细地分析已确定的机制，以揭示衰老和生殖/寿命权衡的明显逆转的途径和网络。通过在白蚁身上做这项工作，我们将研究最古老的群居昆虫和膜翅目以外进化出共生社会的最大谱系。我们有三个目标：在焦点B“调节器”所有项目的共同努力中，我们将在目标1中调查蛋白质供应对女王繁殖力的作用。在此过程中，我们将重点关注TI-J-LIFE网络的TOR部分。我们将检验这样一种假设，即额外的蛋白质会增加蜂王的繁殖力。通过进行食物补充实验，我们将分析额外的蛋白质来源如何影响蜂王和工蚁的寿命。根据第一个资助阶段的结果，我们将在目标2中测试这样一个假设，即Akt在皇后区改变对FOXO的调控可以解释IIS信号的上调，而不会对FOXO及其下游途径产生负面影响。这里，我们将集中讨论TI-J-LIFE网络中的IIS-JH-卵黄蛋白原部分。目标3将验证TE活动和种姓特有的TE沉默机制有助于解释蜂王和工蚁之间的长寿差异以及生殖力/长寿权衡的逆转的假设。我们的研究将对衰老的机制和生育/寿命权衡的逆转提供见解，这将有助于揭示分子制约和谱系特有的特性。

Reversal of the fecundity/longevity trade-off evolved several times independently with sociality. This provides strong support for the hypothesis that sociality, fecundity and lifespan influence each other during evolution. Our molecular results from the first funding phase indicate convergent evolution at the pathway level. For all studied species, we identified caste-specific, age-related changes in the network along the TOR (target of rapamycin)/IIS (insulin/insulin-like growth factor1 signalling) - juvenile hormone (JH) axis that affects pathways linked to lifespan and fecundity (the TI-J-LiFe network for TOR/IIS-JH-Lifespan Fecundity). Yet details seem to differ between species. In addition, we found for termites a strong signal of age-related transposable element (TE) activity, which we did not detect in the social Hymenoptera. These ‘jumping genes’ have long been hypothesized to play a role in ageing in animals and recently a causal link has been demonstrated. During the second funding phase, we aim to analyse the identified mechanisms in more detail by performing functional experiments in a termite to reveal pathways and networks underlying ageing and the apparent reversal of the fecundity/longevity trade-off. By doing this in termites, we will study the oldest social insects and the largest lineage outside the Hymenoptera that evolved eusociality. We have three Objectives:In a common effort shared across all projects in Focus B ‘Regulators’, we will investigate in Objective 1 the role of protein availability for queen fecundity. In doing so, we will focus on the TOR part of the TI-J-LiFe network. We will test the hypothesis that additional protein increases the fecundity of queens. By undertaking a food-supplement experiment, we will analyse how queen and worker longevity are affected by additional protein sources. Based on results from the first funding phase, we will test in Objective 2 the hypothesis that a change in the regulation of FOXO by Akt in queens can account for an upregulation of IIS signalling without negative consequences on FOXO and its downstream pathways. Here we will concentrate on the IIS-JH-Vitellogenin part of the TI-J-LiFe network. Objective 3 will test the hypothesis that TE activity and caste-specific TE silencing mechanisms contribute to explain longevity differences between queens and workers and the reversal of the fecundity/longevity trade-off. Our studies we will offer insights into mechanisms of ageing and the reversal of the fecundity/longevity trade-off that will help to reveal molecular constraints and lineage specific idiosyncrasies.