人類目前測序完畢的第二大基因組屬于一種神奇的小生物。它叫做美洲大蠊，在中國被稱為“小強”，其基因組比人類的還要龐大。

這種昆蟲如何以各色食物維生，如何在惡劣環境下生存，又是如何在沒有頭的情況下存活一周并長出新的肢體？這一切奧秘都隱藏在其遺傳密碼之中。

廣州華南師范大學的研究人員對這種頑強昆蟲的基因組進行了測序，并把研究成果發表在了上周的《自然通訊》（Nature Communications）上。

他們發現，蟑螂有關免疫系統、感官知覺、解毒、生長和繁殖的基因組十分龐大，這解釋了它們為何可以存活于各種各樣的環境中——以及為何難以被殺死。

昆蟲學家、論文的第一作者李勝在接受《紐約時報》（New York Times）采訪時表示：“這種昆蟲很小，卻有很強的生命力。”

自花費十余年時間、耗資近27億美元對人類基因組首次測序以來，醫學研究人員就找到了賦予生物體抗病能力的途徑。此外，CRISPR（規律成簇的間隔短回文重復）技術也推動著醫療領域向廉價和簡便的DNA編輯方面發展。

科學家正在研究美洲大蠊等物種，探究那些讓它們適應性和生命力如此強大的性狀在DNA中的編碼方式。除了蝗蟲以外，美洲大蠊的基因組比其他任何已知昆蟲的基因組都要龐大。

蟑螂的基因信息可以從以下幾個方面幫助人類：

安全

研究人員發現，美洲大蠊擁有超過1,000個基因幫助它們辨識環境中的化學物質。

其中超過300個基因都與苦味感受相關，蟑螂可以借此獲取大量有關食物是否安全的信息。還有一些基因可以幫助它們抵御有毒環境，產生大量分解毒素的酶類，并強化免疫系統。

害蟲防治

這些基因在體現蟑螂頑強生命力的同時，也可以讓人類找出擺脫它們的方式。

科學家修改了這些昆蟲有關免疫系統、生殖和發育系統的超過20個基因，給它們帶來了毀滅性的影響。這為害蟲防治開辟了新的道路，類似于孟山都（Monsanto）開發的基因嵌入式殺蟲劑。

自愈特性

美洲大蠊可以再生失去的肢體。科學家在試驗中切掉了它們的肢體，觀察了再生過程，發現蟑螂的DNA會促進愈合和再生。

在傳統中藥里，蟑螂一直被用于治療割傷和燒傷，但研究人員將進一步探索這些昆蟲如何產生新的組織，希望借此開辟人類醫療上的新未來。

李勝表示：“我們知道了它得名‘小強’的秘密，現在我們希望發掘中藥里的秘密。”

社會行為

科學家希望通過研究蟑螂和白蟻，發掘昆蟲社會性——即它們進行分工合作——的遺傳來源。

通過最近的研究，人們發現白蟻與蟑螂的關系較以往所認為的更近，它們比蜜蜂和螞蟻等昆蟲更早演化出了這一特性。（財富中文網）

譯者：嚴匡正

The second-largest genome ever sequenced belongs to a small but fascinating creature. Called “xiao qiang” or “little mighty” in China, the American cockroach has a genome larger than that of humans.

It’s genetic code holds the secrets to how these insects can survive on so many different types of food and in such unfriendly habitats, or even how it can survive for a week without a head and grow replacement limbs.

Researchers at South China Normal University in Guangzhou sequenced the genome of the hardy insect and published their findings in Nature Communications last week.

They found that the groups of genes related to the immune system, sensory perception, detoxification, and growth and reproduction were all enlarged, helping to explain how cockroaches are able to live in so many different environments — and why it’s so hard to kill them.

“It’s a tiny pest, but has very strong vitality,” Sheng Li, the lead author of the paper and entomology professor, told the New York Times.

Since sequencing the first human genome, which took more than a decade and nearly $2.7 billion, medical researchers have found ways to make organisms resistant to disease. Also, CRISPR technology has moved the medical field toward cheap and and easy DNA editing.

Scientists are looking to species like the American cockroach to learn about how traits that make them incredible adapters and stubborn survivalists are encoded in their DNA. Compared to other insects, the American cockroach genome is larger than any known genome sequence except locusts.

Here are a variety of ways this information about roaches can help humans:

Safety

The researchers found that American cockroaches have more than 1,000 genes that help them read chemical cues in their environment.

More than 300 of these genes relate to sensing bitter tastes, giving cockroaches plenty of information about which foods are and are not safe to eat. The bugs also have genes that allow them to withstand toxic environments and a higher number of enzymes that break down toxins in addition to their stronger immune systems.

Pest Control

The genes that show why cockroaches are so hardy also give clues about how to get rid of them.

Scientists manipulated more than 20 genes related to the immune system, reproductive system, and development, revealing damaging effects on the insects. This could show a path toward creating new pest control methods, similar to the genetically embedded insecticides Monsanto has developed.

Healing Properties

The American cockroach will regenerate lost limbs. By amputating limbs during their research and monitoring their regrowth, scientists found that genes in the cockroach’s DNA prompt healing and regeneration.

Cockroaches have long been used in traditional Chinese medicine for treating cuts and burns, but researchers will study how the insects generate new tissue in hopes of unlocking future medical applications for humans.

“We’ve uncovered the secret of why people call it ‘xiao qiang,’ ” Li said. “Now we want to know the secrets of Chinese medicine.”

Social Behaviors

By studying cockroaches and termites, scientists hope to uncover the genetic origins of eusociality, which causes organisms to work together and cooperate in dividing labor.

Termites, which recent research shows are more closely related to cockroaches than originally thought, developed this trait much earlier than insects like bees and ants.