Crazy ants’ strange genomes are a biological first

黄疯蚁奇特的基因组是生物学上的首次（发现）

Males of the notorious yellow crazy ant carry a mixture of genomes, a phenomenon unseen in other animals.

臭名昭著的雄性黄疯蚁携带混合基因组，这是一种在其他动物中前所未见的现象。

Ewen Callaway（作者）

Yellow crazy ants get their name from the helter-skelter movements they make after a disturbance.

黄疯蚁因它们在骚乱后做出杂乱无章的动作而得名。

But there’s another reason to call these invasive ants crazy: males of the species are a mixture of two warring cell lineages, researchers report in a study published on 6 April in Science. Other creatures sometimes form such chimaeras — usually a developmental accident — but yellow crazy ants are the first known animal for which this property is an essential aspect of life.

但还有另一种原因能称这些入侵的蚂蚁疯狂：研究人员在4月6日发表在《科学》杂志上的一项研究报告称，该物种的雄性是两个敌对细胞系的混合物。其他动物有时会形成这样的嵌合体——通常是一种进化意外——但黄疯蚁是已知的首个将这种性质作为生命中必不可少的动物。

“It’s a piece of biology that’s unparalleled as far as we know,” says Daniel Kronauer, a biologist at the Rockefeller University in New York City.

纽约市洛克菲勒大学的生物学家Daniel Kronauer说：“据我们所知，这是一种前所未有的生理现象。”

Yellow crazy ants (Anoplolepis gracilipes) are a notorious invasive species mainly distributed across southeast Asia and Oceania, threatening invertebrates and even some small mammals. On Christmas Island, an Australian territory south of Java, the ants have decimated populations of red crabs, which are endemic to the region.

黄疯蚁（细足捷蚁）是一种臭名昭著的入侵物种，主要分布在东南亚和大洋洲，对无脊椎动物甚至一些小型哺乳动物构成威胁。这种蚂蚁大量捕杀了在爪哇岛以南的澳大利亚领土圣诞岛上特有的红蟹。

The first clues to the ants’ weird biology came from studies of genetic markers peppered across their genomes. Males seemed to carry two versions of many genetic markers. This was a perplexing feature, because in most ant species, the males develop from unfertilized eggs and therefore have just one genome copy.

黄疯蚁不同寻常的生理现象的第一条线索来自于对遍布其基因组的基因标记的研究。雄性似乎携带有许多基因标记的两种变体。这是一个令人困惑的特征，因为在大多数蚂蚁中，雄蚁是从未受精的卵中发育而来的，因此只有单拷贝基因。

Some ant species occasionally have ‘diploid’ males with two genome copies, but these males are usually sterile. “It was really weird that all the males in this species would be diploid,” says Hugo Darras, an evolutionary biologist at the Johannes Gutenberg University Mainz in Germany. “It didn’t make sense at all.”

一些蚂蚁偶尔会有两个基因组拷贝的“二倍体”雄性，但这些雄性通常是不育的。德国美因茨约翰尼斯古腾堡大学的进化生物学家Hugo Darras说：“这个物种中所有的雄性都是二倍体，这真的很奇怪，这完全没有道理。”

Genome copies

基因组拷贝

To determine what was going on, Darras and his colleagues analysed individual cells from yellow crazy ants collected across southeast Asia. This showed that each male cell contained just one version of the ant’s genome. But this genome differed between cells. Some harboured a lineage present in queens, and defined by an ‘R’ chromosome, whereas other cells carried a lone copy of a different genome, with a ‘W’ chromosome.

为了查明究竟发生了什么，Darras和他的同事分析了东南亚各地采集的黄疯蚁的独立细胞。这表明，每个雄性细胞只包含这种蚂蚁基因组的一个变种。但是细胞间的基因组不同。一些细胞携带有蚁后中存在的（细胞）谱系，定义为“R”染色体，而其他细胞携带不同的基因组单独拷贝，定义为“W”染色体。

The cells of queen ants have two copies of the W genome, whereas sterile female worker ants have one copy of each lineage in every cell. Darras’s team found that males’ chimaerism has a crucial role in the ants’ caste system.

蚁后的细胞有两个W基因组拷贝，而不孕的雌性工蚁在每个细胞的每个谱系中都有单拷贝基因。Darras的团队发现，雄性的嵌合现象在蚂蚁的社会等级制度中起着至关重要的作用。

All the queen’s eggs carry one copy of the R genome. If this egg is fertilized by a sperm cell with an R genome, a queen develops. However, if the egg is inseminated with a W sperm, there are two possible outcomes. If the two genome-containing cell nuclei fuse, a diploid worker ant develops. If the nuclei do not fuse, the egg develops as a chimaeric male, some cells carrying an R and others carrying a W genome.

所有蚁后的卵子都携带一个R基因组拷贝。如果这个卵子被一个具有R基因组的精子细胞受精，就会发育出一个蚁后。然而，如果这个卵子被携带有W基因组的精子受精，会出现两种可能的结果。如果含有两个基因组的细胞核融合，就会发育成一只二倍体工蚁。如果细胞核没有融合，卵子就会发育成嵌合雄性，一些细胞携带R基因组，另一些细胞携带W基因组。

“This is great,” says Monica Gruber, an applied ecologist at Wellington UniVentures in New Zealand, who co-authored a 2013 study that raised the possibility of chimaerism in males. “They finally cracked the enigma that kept me awake at night for much of my PhD.”

“这太棒了，” Monica Gruber说，这是一位新西兰惠灵顿联合风险投资公司的应用生态学家，他与人合作了2013年的一项研究，该研究提出了男性嵌合症的可能性。“他们终于解开了令我在博士学位的大部分时间里夜不能寐的谜团。”

Crazy yellow ants’ chimaerism could contribute to the species ability to evade ecosystems, says Kronauer. Queens have specialized organs that store sperm from multiple males. That means a lone queen storing R and W sperm can start a new ant colony. Lori Lach, an ecologist at James Cook University in Cairns, Australia, wonders if researchers could take advantage of their quirky biology to keep small ant populations from turning into big ones.

Kronauer说，黄疯蚁的嵌合现象可能赋予该物种逃避生态系统的能力。蚁后有专门的器官来储存多个雄性的精子。那意味着一只储存有R和W基因组精子的蚁后能够创建一个新的蚁群。澳大利亚凯恩斯市的詹姆斯·库克大学的生态学家Lori Lach想知道研究人员是否可以利用它们奇特的生物学特性，防止小蚂蚁种群变成大蚂蚁种群。

But the discovery raises as many questions as it answers. It’s not clear why the nuclei of some sperm fail to fuse with the egg nucleus, resulting in chimaeric males. Genes in W lineage cells — which are over-represented in sperm — might play a part, says Durras. “There’s so much we don’t know.”

但这一发现提出的问题和它回答的问题一样多。目前尚不清楚为什么一些精子的细胞核不能与卵子的细胞核融合，从而导致雄性嵌合。Durras说，W细胞谱系中的基因——在精子中过度表达——可能起到了一定作用。“我们有太多不知道的了。”

doi: https://doi.org/10.1038/d41586-023-01002-3

（本翻译仅用于本人学习英语，关于生物学术语可能翻译不准确，请谅解）