60秒科学:多细胞生物不需要氧气
As scientists delve 1 deeper beneath the ocean’s surface, they find bizarre creatures that have adapted to harsh and extreme environments. Now comes a new one—the discovery of the first multicellular animals that survive and reproduce entirely 2 without oxygen. Researchers had thought that only single-celled organisms such as prokaryotes and protozoa could live in the oxygen-deprived environments of the deepest ocean. When scientists did find multicellular organisms, they assumed that they’d sunk from oxygen-enriched waters.
But over the past decade, scientists in Italy and Denmark sent three expeditions to fetch samples from sediment 3 in what’s known as a deep hypersaline anoxic basin in the Mediterranean 4. And in these sediments 5, from almost two miles below the ocean’s surface, they found three distinct species of a tiny multicellular animal phylum called Loricifera.
They don’t have mitochondria. Instead, they seem to have organelles that resemble hydrogenosomes—similar to mitochondria, but that use anaerobic 6 chemistry. Scientists don’t yet fully 7 understand the biochemistry—but the discovery opens the possibility of complex life forms on oxygen-free planets.
—Cynthia Graber
- We should not delve too deeply into this painful matter.我们不应该过分深究这件痛苦的事。
- We need to delve more deeply into these questions.这些是我们想进一步了解的。
- The fire was entirely caused by their neglect of duty. 那场火灾完全是由于他们失职而引起的。
- His life was entirely given up to the educational work. 他的一生统统献给了教育工作。
- The sediment settled and the water was clear.杂质沉淀后，水变清了。
- Sediment begins to choke the channel's opening.沉积物开始淤塞河道口。
- The houses are Mediterranean in character.这些房子都属地中海风格。
- Gibraltar is the key to the Mediterranean.直布罗陀是地中海的要冲。
- When deposited, 70-80% of the volume of muddy sediments may be water. 泥质沉积物沉积后，体积的70-80％是水。
- Oligocene erosion had truncated the sediments draped over the dome. 覆盖于穹丘上的沉积岩为渐新世侵蚀所截削。
- Anaerobic respiration occurs only in particularly active tissues such as muscles during severe exercise. 厌氧呼吸只有在处于剧烈运动状态的肌肉等特别活跃的组织中才会发生。
- Infection,especially anaerobic infection, is much more apt to occur.感染，特别是厌氧感染很容易发生。