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This is Scientific American — 60-Second Science. I'm Karen Hopkin.
"Lichens are really cool successful organisms that are composed of at least two symbiotic partners: a fungal partner that provides structure and protection and a photosynthetic partner that likely provides energy in the form of sugar."
Cloe Pogoda, a graduate researcher at the University of Colorado. She led research that found that this partnership extends to the genetic level. The fungal partner in many lichen jettison a gene that's critical for energy production—making them completely dependent on their algal associates.
Although scientists have long appreciated that general division of labor, what's been less clear is whether the relationship was entirely obligatory. In other words, are the cohorts changed by their evolutionary association in such a way that they can no longer make it alone?
To find out, the team sequenced the genomes of 22 lichen species collected in the southern Appalachian Mountains. And they concentrated on the participants' mitochondria, which contain genomes of their own.
"Because there are so many copies of these genomes in each cell, and because they're so conserved across all domains of life, the mitochondrial genomes were the focus of our study." Kyle Keepers, also at the University of Colorado.

What the researchers found is that a key mitochondrial gene was missing from the fungal partner in 10 of the lichen species they examined. These species hailed from three different evolutionary lineages.
CP: "This is a really cool result because it demonstrates that this lichen relationship is obligate. And that the same strategy for genome streamlining was employed three different times over evolution." The findings appear in the journal Molecular Ecology.
Genome streamlining makes sense because it reduces redundancy on a molecular level.
"Think of it like two partners moving in together. And they each have their own printer. Who needs two printers?" Erin Tripp, the study's principal investigator, is the curator of botany at the university's Museum of Natural History.
Letting the algae provide the cellular energy likely makes the fungal partner more efficient, perhaps allowing it to focus on building a stable structure and reproducing. Tripp wonders whether some of the bacteria living in our guts might have developed similar molecular co-dependencies.
ET: "What this data analysis pipeline, moreover, creates is motivation to look for similar forms of gene loss in other types of symbioses, such as that between humans and their gut microbiomes. It may very well be that some bacteria are completely dependent on their human hosts and thus coevolving with us, whereas others can come and go."
Thanks for listening for Scientific American — 60-Second Science. I'm Karen Hopkin.

参考译文

这里是科学美国人——60秒科学jJGC)|,|[7u)。我是凯伦·霍普金KC0Q!xr&YYorluUqOZ。
有一分钟时间吗？
“地衣是非常成功的生物体，它由至少两个共生伙伴组成：一个提供结构和保护的真菌伙伴，以及一个很可能以糖形式提供能量的光合作用伙伴.UcvMIMoB]9P。”
科罗拉多大学的研究生研究员克罗伊·波哥达说到J]H7tszWN0w。她领导的一项研究发现，这种伙伴关系延伸到了基因层面Rq59vifYNqdjXl]。许多地衣中的真菌伙伴会抛弃产生能量的关键基因，这使它们完全依赖于藻类伙伴2rV8Vj[K9!f。
虽然科学家长期以来一直欣赏这种普遍分工关系，但是他们还不太清楚这种关系是否是完全专性的q,7-zM(k^k^AM。换句话说，这些真菌群是否会被进化的伙伴所改变，以致于无法再独自生存？
为了找到答案，该团队对从阿巴拉契亚山脉南部地区收集的22种地衣进行了基因组排序i*Q(slysB*-1[。他们专注于研究包含地衣基因组的线粒体_ig7^XuTUkg#。
“因为每个细胞内有很多线粒体基因组，而且因为它们存在于所有生物域中，因此线粒体基因组是我们的研究重点s#ud|vk6neO。”科罗拉多大学的凯尔·基伯斯说;Uo^~dD&%DgX。
研究人员发现，在他们检测的地衣中，有10种地衣的真菌伙伴缺失了关键线粒体基因m7P)JFr8U4-K^4AF#d。这10种地衣来自三支不同的进化谱系JL9L7j,79AVnLQ~PL^=。
克罗伊·波哥达：“这结果非常美妙，因为它证明了这种地衣伙伴关系是专性的5,oU3fO*CIbL,ZW9IHV。而且，同样的基因组精简策略在进化过程中出现了三次m_qyRlPi2q。”这项研究结果发表在《分子生态学》期刊上=)4jw~Fa4gRaaTe。
基因组精简具有意义，因为这可以减少分子层级的冗余_%u[g,0RWE^(9v。
“就好像两个搬到一起住的伙伴hCgeibUgIzYk-kLn9h。他们两个人都有自己的打印机33nzV3wS+=0ue6=W。谁会需要两台打印机呢？”该研究的首席研究员艾琳·特里普说到，她是科罗拉多大学自然历史博物馆的植物学馆长-gn0L7axT*c[U*BP。
让藻类提供细胞能量很可能会提高真菌伙伴的效率，或许可以让它专注于建立稳定的结构并进行繁殖9uVJtZ5PljeYJarp,JF~。特里普想知道，这些生活在我们肠道中的细菌是否也发展出了类似的分子共依存性E5X2zhYqlj@S5Kbbs。
艾琳·特里普：“此外，这一数据分析流程还产生了动力，在其他共生类型中寻找类似形式的基因缺失现象，比如人类及体内肠道微生物之间的共生关系+VYSTbgCL442tP=6。有些细菌很可能完全依赖于人类宿主，继而与我们共同进化，而其他细菌则可以来去自如.=[M%X^^0ndC=a|cZg。”
谢谢大家收听科学美国人——60秒科学deV[kb@VC=Rg!eZ-waRi。我是凯伦·霍普金~vZ1QZk_[B^h%Ay9bw。

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重点讲解

重点讲解：
1. be composed of 组成；构成；
All animals and plants are composed of cells.
一切动植物均由细胞组成-q%b=8D%8Y。
2. concentrate on 全神贯注;集中（心思）；
I am leaving to concentrate on writing fiction.
我辞职是为了专心写小说jE6i.,X-R6W)uR)l!h8。
3. hail from （人或物）来自；
They hail from all parts of the country.
他们来自全国各地[v9QB^Cjtt!gIlRf|Bux。
4. be dependent on 取决（于…）的；有赖（于…）的；
Up to two million people there are dependent on food aid.
那里有多达200万人口依靠食品援助@3sd7@4O-fkH。