美國科研人員捕捉到一種極不尋常的生物：一種以海藻為食并將海藻色素吸收到自身細(xì)胞中的海蝸牛。更令人驚訝的是，這種蝸牛不僅能借此進(jìn)行很好的偽裝,，還能像植物一樣進(jìn)行光合作用以獲取能量。
美國緬因州大學(xué)的蝸牛研究者發(fā)現(xiàn),，這種海蝸牛在生命初期以海藻為食,，但卻并不完全消化海藻，而是將其中的綠色素吸收進(jìn)自己的細(xì)胞,。它們吃的海藻越多,，其顏色就變得越綠。
讓研究者感到驚訝的是,，這種蝸牛不僅能借此進(jìn)行偽裝,，甚至還會從一種活性生命狀態(tài)過渡到一種大體上的植物狀態(tài)。因?yàn)橐坏┧鼈冞M(jìn)食海藻變綠后,，就能在沒有任何食物的情況下生存數(shù)月之久,。它們只靠水和自身體內(nèi)綠色素通過光合作用制造的能量生存。
以詹姆斯·曼哈特為首的科研人員在《國家科學(xué)院學(xué)報(bào)》上撰文描述了這種名為Elysia chlorotica的海蝸牛,。曼哈特說：“Elysia的生長需要海藻,，沒有海藻它們無法活下來,。不過，一旦它們偷到充足的綠色素就會立即變成一種帶有太陽能動力裝置的動物,。”
科學(xué)家認(rèn)為,，在遙遠(yuǎn)的未來，這種蝸牛甚至有可能將綠色素遺傳給后代,。到那時,，它們就不必在生命的初始階段進(jìn)食海藻了，而且將成為第一種通過光合作用獲取能量的動物,。（生物谷Bioon.com）
生物谷推薦原始出處：
PNAS 2008 105:17867-17871;doi:10.1073/pnas.0804968105
Horizontal gene transfer of the algal nuclear gene psbO to the photosynthetic sea slug Elysia chlorotica
Mary E. Rumpho, Jared M. Worful, Jungho Lee, Krishna Kannan, Mary S. Tyler, Debashish Bhattacharya, Ahmed Moustafa, and James R. Manhart
The sea slug Elysia chlorotica acquires plastids by ingestion of its algal food source Vaucheria litorea. Organelles are sequestered in the mollusc's digestive epithelium, where they photosynthesize for months in the absence of algal nucleocytoplasm. This is perplexing because plastid metabolism depends on the nuclear genome for >90% of the needed proteins. Two possible explanations for the persistence of photosynthesis in the sea slug are (i) the ability of V. litoreaplastids to retain genetic autonomy and/or (ii) more likely, the mollusc provides the essential plastid proteins. Under the latter scenario, genes supporting photosynthesis have been acquired by the animal via horizontal gene transfer and the encoded proteins are retargeted to the plastid. We sequenced the plastid genome and confirmed that it lacks the full complement of genes required for photosynthesis. In support of the second scenario, we demonstrated that a nuclear gene of oxygenic photosynthesis, psbO, is expressed in the sea slug and has integrated into the germline. The source of psbO in the sea slug is V. litoreabecause this sequence is identical from the predator and prey genomes. Evidence that the transferred gene has integrated into sea slug nuclear DNA comes from the finding of a highly diverged psbO 3′ flanking sequence in the algal and mollusc nuclear homologues and gene absence from the mitochondrial genome of E. chlorotica.We demonstrate that foreign organelle retention generates metabolic novelty (“green animals”) and is explained by anastomosis of distinct branches of the tree of life driven by predation and horizontal gene transfer.
