Crazy ants’ strange genomes are a biological first

黃瘋蟻奇特的基因組是生物學(xué)上的首次（發(fā)現(xiàn)）

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

臭名昭著的雄性黃瘋蟻攜帶混合基因組，這是一種在其他動(dòng)物中前所未見(jiàn)的現(xiàn)象。

Ewen Callaway（作者）

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

黃瘋蟻因它們?cè)隍}亂后做出雜亂無(wú)章的動(dòng)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.

但還有另一種原因能稱這些入侵的螞蟻瘋狂：研究人員在4月6日發(fā)表在《科學(xué)》雜志上的一項(xiàng)研究報(bào)告稱，該物種的雄性是兩個(gè)敵對(duì)細(xì)胞系的混合物。其他動(dòng)物有時(shí)會(huì)形成這樣的嵌合體——通常是一種進(jìn)化意外——但黃瘋蟻是已知的首個(gè)將這種性質(zhì)作為生命中必不可少的動(dòng)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.

紐約市洛克菲勒大學(xué)的生物學(xué)家Daniel Kronauer說(shuō)：“據(jù)我們所知，這是一種前所未有的生理現(xiàn)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.

黃瘋蟻（細(xì)足捷蟻）是一種臭名昭著的入侵物種，主要分布在東南亞和大洋洲，對(duì)無(wú)脊椎動(dòng)物甚至一些小型哺乳動(dòng)物構(gòu)成威脅。這種螞蟻大量捕殺了在爪哇島以南的澳大利亞領(lǐng)土圣誕島上特有的紅蟹。

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.

黃瘋蟻不同尋常的生理現(xiàn)象的第一條線索來(lái)自于對(duì)遍布其基因組的基因標(biāo)記的研究。雄性似乎攜帶有許多基因標(biāo)記的兩種變體。這是一個(gè)令人困惑的特征，因?yàn)樵诖蠖鄶?shù)螞蟻中，雄蟻是從未受精的卵中發(fā)育而來(lái)的，因此只有單拷貝基因。

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.”

一些螞蟻偶爾會(huì)有兩個(gè)基因組拷貝的“二倍體”雄性，但這些雄性通常是不育的。德國(guó)美因茨約翰尼斯古騰堡大學(xué)的進(jìn)化生物學(xué)家Hugo Darras說(shuō)：“這個(gè)物種中所有的雄性都是二倍體，這真的很奇怪，這完全沒(méi)有道理?！?/span>

Genome copies

基因組拷貝

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.

為了查明究竟發(fā)生了什么，Darras和他的同事分析了東南亞各地采集的黃瘋蟻的獨(dú)立細(xì)胞。這表明，每個(gè)雄性細(xì)胞只包含這種螞蟻基因組的一個(gè)變種。但是細(xì)胞間的基因組不同。一些細(xì)胞攜帶有蟻后中存在的（細(xì)胞）譜系，定義為“R”染色體，而其他細(xì)胞攜帶不同的基因組單獨(dú)拷貝，定義為“W”染色體。

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.

蟻后的細(xì)胞有兩個(gè)W基因組拷貝，而不孕的雌性工蟻在每個(gè)細(xì)胞的每個(gè)譜系中都有單拷貝基因。Darras的團(tuán)隊(duì)發(fā)現(xiàn)，雄性的嵌合現(xiàn)象在螞蟻的社會(huì)等級(jí)制度中起著至關(guān)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.

所有蟻后的卵子都攜帶一個(gè)R基因組拷貝。如果這個(gè)卵子被一個(gè)具有R基因組的精子細(xì)胞受精，就會(huì)發(fā)育出一個(gè)蟻后。然而，如果這個(gè)卵子被攜帶有W基因組的精子受精，會(huì)出現(xiàn)兩種可能的結(jié)果。如果含有兩個(gè)基因組的細(xì)胞核融合，就會(huì)發(fā)育成一只二倍體工蟻。如果細(xì)胞核沒(méi)有融合，卵子就會(huì)發(fā)育成嵌合雄性，一些細(xì)胞攜帶R基因組，另一些細(xì)胞攜帶W基因組。

“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.”

“這太棒了，” Monica Gruber說(shuō)，這是一位新西蘭惠靈頓聯(lián)合風(fēng)險(xiǎn)投資公司的應(yīng)用生態(tài)學(xué)家，他與人合作了2013年的一項(xiàng)研究，該研究提出了男性嵌合癥的可能性?！八麄兘K于解開(kāi)了令我在博士學(xué)位的大部分時(shí)間里夜不能寐的謎團(tuán)?！?/span>

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說(shuō)，黃瘋蟻的嵌合現(xiàn)象可能賦予該物種逃避生態(tài)系統(tǒng)的能力。蟻后有專門的器官來(lái)儲(chǔ)存多個(gè)雄性的精子。那意味著一只儲(chǔ)存有R和W基因組精子的蟻后能夠創(chuàng)建一個(gè)新的蟻群。澳大利亞凱恩斯市的詹姆斯·庫(kù)克大學(xué)的生態(tài)學(xué)家Lori Lach想知道研究人員是否可以利用它們奇特的生物學(xué)特性，防止小螞蟻種群變成大螞蟻種群。

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.”

但這一發(fā)現(xiàn)提出的問(wèn)題和它回答的問(wèn)題一樣多。目前尚不清楚為什么一些精子的細(xì)胞核不能與卵子的細(xì)胞核融合，從而導(dǎo)致雄性嵌合。Durras說(shuō)，W細(xì)胞譜系中的基因——在精子中過(guò)度表達(dá)——可能起到了一定作用。“我們有太多不知道的了?！?/span>

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

（本翻譯僅用于本人學(xué)習(xí)英語(yǔ)，關(guān)于生物學(xué)術(shù)語(yǔ)可能翻譯不準(zhǔn)確，請(qǐng)諒解）