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  • Now, this is a guess, because I wasn't there, and we don't have any clear records of this period of history, but at some point, in the early history of life on earth, it's very likely nothing could move.

    這只是猜的,畢竟我當時不在那,而且也沒有當時的歷史記錄,但在地球生物誕生初期,很可能沒有任何東西會移動。

  • Cells existed where they were, they got sloshed around through physical processes, and survived when they ended up, by chance, in some place that had the necessary chemicals for them to continue their lives and reproduce.

    細胞就處在他們所處的地方,透過物理過程四處遊蕩,要是剛好停留在一個有必要化學物質、足以供他們生存繁殖的地方,他們就會存活。

  • If that didn't happen they just died.

    若非如此,他們就會死亡。

  • But since food is never evenly distributed in our world, and also sometimes you are food, being able to move is fantastic, and so it has been selected for pretty intensely so that, now, in the microcosmos, almost everything moves.

    但由於食物並非平均散佈於各地,甚至有時候自己就是別人的食物,能夠移動其實是很棒的事,所以經過嚴格篩選後,現在在微觀世界裡,幾乎一切都會移動。

  • But before we get to how they do it, we have to confront a reality.

    但在探究他們如何移動前,我們必須先正視現實。

  • You need to forget everything you know about swimming.

    你必須先忘記你對游泳的所有認知。

  • Things do not work the same when you are tiny.

    如果你很迷你,事情運作的方式就會不同。

  • You and I are constantly moving through a fluid, it's just hard to feel it, air.

    你我不斷在一種液體中移動,雖然很難察覺到,也就是空氣。

  • It's barely there, until you stick your hand out of a car window on the highway.

    幾乎認知不到,直到你在高速公路上將手伸出車窗。

  • Then you feel that fluid.

    你就感覺到了。

  • But for a tiny grain of pollen, air is a thick fluid that can keep it airborne for days.

    但對一小顆花粉而言,空氣是一種濃厚的液體,有可能讓它困在空中好幾天。

  • Now sink that tiny grain of pollen into far more viscous water, and it's basically in a sticky, glue.

    現在將那一小顆花粉沉進相比起來稠密得多的水,它基本上等同進到了黏糊糊的漿糊裡。

  • Imagine being completely submerged in honey and you have a vague idea of what it's like swimming in the microcosmos.

    想像被完全浸泡在蜂蜜中,那你就能大略了解微觀世界中的「游泳」是怎麼回事。

  • Which is why, in that microscopic world, when something stops moving, it just stops.

    這也是為什麼在顯微鏡的世界中,當一個東西停止移動,就會瞬間停止。

  • You and I, if we push through the water, we'll coast for a bit as our momentum carries us forward, but for a single cell, the viscosity of the water overcomes that inertia instantly.

    我們如果在水中推行,我們會被動力帶得往前滑行一小段,但對一個細胞來說,水的稠密度瞬間克服慣性。

  • This can lead to organisms looking as if they are moving somewhat unnaturally to our eyes, which is we think why we've had several people have ask us if our footage is sped up.

    這使得微生物在我們看來移動得很奇怪,我想這也是為什麼有許多人問我們鏡頭是不是有加速。

  • But, no, unless it says so on-screen, all of our clips are in real time.

    不過並沒有,除非螢幕上有特別標示,我們所有的影片都是實時的。

  • These little folks can just move!

    這些小傢伙就是…直接移動!

  • And they need to move... to search for food, to avoid predators, to get into or out of sunlight, to move toward chemicals they need, or away from chemicals that poison them.

    他們也必須移動,才能尋找食物、躲避獵食者、進入或是躲避光照、靠近所需的化學物質,或是遠離有害的化學物質。

  • And the wild thing is, with all of the diversity of microscopic life single celled eukaryotes basically all move around in three or maybe four different ways.

    而且瘋狂的是,在微觀世界的多樣性中,單細胞真核生物基本上用三或四種不同的方式移動。

  • How organisms move is so important, and so obvious when they're observed, that protozoans, which is the general name for single-celled eukaryotes, are actually loosely classified by their style of movement.

    微生物移動的方式至關重要,而且觀察時這點也最為突出,一種稱為原生生物的單細胞真核生物因而依據移動方式來分類。

  • We've got ciliates, which move using cilia, flagellates, which move using flagella, and amoeboids, which move using pseudopodia.

    比如用纖毛移動的纖毛蟲、用鞭毛移動的鞭毛蟲、用偽足移動的變形蟲。

  • Oh... and then there's Sporozoawhich we can't show you a picture of, for reasons that will become clear.

    噢 … 還有孢子蟲,我們沒辦法給你看圖片,原因等會揭曉。

  • Sporozoa almost never move, and when they do it's in a very weird limited way.

    孢子蟲幾乎從不移動,當他們移動時,也是用一種非常怪異受限的方式。

  • And the reason we can't show you a picture of one is that they are, every one of them, parasites.

    我們無法給你看他的圖片是因為,他們每一種都是寄生蟲。

  • Many of them live inside of, and cause disease in animals so we choose to, you know, not keep them around.

    他們多數住在動物體內並造成疾病,所以我們決定,你瞭的,就不留在手邊了。

  • But, overall, among eukaryotes we've got cilia, flagella, and pseudopodia.

    但整體而言,在真核生物的世界裡,就有纖毛、鞭毛和偽足。

  • And we're going to start with the shapeshifters of the Microcosmos, amoeba!

    我們從微觀世界的變形者開始,阿米巴原蟲!

  • These cells can change their shape as they wish, allowing them to extend parts of themselves into features called pseudopodia.

    這些細胞可以任意改變身形,能夠伸出部分的身體形成偽足。

  • These extend in the direction they want to move, and then solidify as the cell moves into the newly occupied space.

    這些偽足往他們想移動的方向擴展,然後在細胞移進下一個空間時固態化。

  • is latin for, basically, false feet, and these extensions which are half reaching arm, half cell body are how these crawlers move and hunt.

    pseudopodia 是拉丁文,基本上就是指假的腳,這些一半是延展臂、一半是細胞身體的延伸物就是這些爬行動物移動和狩獵的方法。

  • The secret here is that the cytoplasm of an amoeba can be easily changed from a fluid state into a solid state and back again.

    秘訣在於阿米巴原蟲的細胞質可以在液態和固態之間來回變換。

  • When an amoeba moves, liquid cytoplasm flows through the center, up to the tip of the pseudopod and then gushes to the sides where it becomes more of a solid gel allowing the cell to lock into its new location.

    當阿米巴原蟲移動時,液態的細胞質會流經中心、到達偽足的頂端,然後湧向兩側成為偏固態的膠體,讓細胞得以固定在新的位置。

  • Predatory amoebae create these extensions in all directions to trap prey between them, once the prey organism is surrounded by the pseudopodia the amoeba simply swallows it.

    獵食性阿米巴原蟲往四周伸出延伸物、困住之間的獵物;微生物一旦被偽足包圍,阿米巴原蟲將其吞下。

  • The two other main mechanisms of eukaryotic movement, cilia and flagella, are more common, and they're actually really similar, both functionally and structurally at the molecular level.

    真核生物的另外兩種主要的移動方式——纖毛及鞭毛——則比較常見,而且其實相當類似,兩者在功能和結構上皆為分子程度。

  • Though they look like rods sticking through the surface, they're actually extensions of the cell membrane wrapped around rigid tubes called microtubules that are anchored in place.

    看起來雖然很像細胞表面伸出棍子,但其實是一種延伸物,由細胞膜包裹住一種稱為微管、有固定位置的固態管子所組成。

  • However, hydrodynamically they're very different.

    然而從流體動力學來看,他們非常不一樣。

  • There are usually an easily countable number of flagella per cell whereas ciliated organisms have huge numbers of cilia.

    每顆細胞的鞭毛數量通常很好計算,但纖毛類的微生物則有非常多的纖毛。

  • The word cilia actually comes from the latin word for eyelash, which makes sense as you can sometimes see them ringing a cell as our eyelashes ring our eyes.

    cilia 一字其實來自拉丁文的「睫毛」,這很有道理,他們圍繞細胞的方式就如同睫毛圍繞我們的雙眼。

  • But, in those cases, the cilia actually often cover the entire cell, they're just harder to spot against the background of all the stuff on the inside.

    但在這些例子中,纖毛其實覆蓋了整個細胞,只是因為背景裡一堆東西所以很難辨認。

  • Cilia move organisms by beating in waves over their surface.

    纖毛在細胞表面拍打出波浪來移動微生物。

  • A cilium, which is the singular of cilia because... latin... has only two possible positions.

    纖毛 (cilium),也就是拉丁文 cilia 的單數,只可能有兩種姿勢。

  • During the effective stroke, the cilium sticks out perpendicular to the cell, and during recovery it folds back towards the cell's surface.

    在有效的撫擺中,纖毛垂直於細胞伸出,而當收回時,它向細胞表層捲起。

  • In most ciliates the cilia are arranged in rows and the cilia of a row don't move all together at once; when some of the cilia are in the effective stroke some are in recovery stroke, and in some ciliates you can see the "wave" pattern this creates.

    大多數纖毛微生物的纖毛呈排狀,每一排纖毛不會同時移動;一些在伸展時,一些則在收回,有時可以看到他們組成的「波浪紋」。

  • These waves are basically grabbing on to the sticky viscous water, yanking the cell through.

    這些波浪基本上就是抓住黏稠的水,將細胞拉過。

  • One added complication here, some ciliates have dense bundles of cilia called cirri.

    更添複雜的是,一些纖毛類微生物還有密集團裝的纖毛,稱為 cirri。

  • Cirri are used to "walk" on a solid substrate rather than pulling the organism through the water.

    cirri 用於在固態的培養基上「行走」,而非在水中拉行微生物。

  • Though it's the same structure, it's a bit of a different system of movement.

    雖然構造一樣,但是在移動系統上有些微差異。

  • Now on to eukaryotic flagella.

    現在輪到鞭毛類真核生物。

  • The motion of most flagella is characterized by this long, wave-like beating pattern beginning from the base of the flagella and moving out to the tip.

    多數鞭毛類的動作特徵就是這條從根部伸到頂部的長條、波浪形拍打形態。

  • This is Phacus longicauda, we recorded this footage in phase contrast which makes the transparent parts of the cell more visible so you can see the beating flagellum better.

    這是長尾扁裸藻,這鏡頭使用相位差顯微鏡,使細胞透明的部分能見,拍打的鞭毛就更容易看見了。

  • Can you see it at the tip of the cell?

    你看到了嗎?就在細胞的頂部。

  • Phacus longicauda is a photosynthetic flagellate... it uses sunlight to produce sugar.

    長尾扁裸藻是一種光合作用型的鞭毛類生物,他利用日光製造糖類。

  • You can see the chloroplasts in the cell like green peas.

    細胞內的葉綠體看起來就像青豆。

  • And the round transparent part at the middle of the cell is a starch-like carbohydrate storage unit called paramylon.

    細胞中央的圓形透明部分則是一個澱粉似的光合作用儲存槽,稱為裸藻醣。

  • Now, of course, as always, the deeper you look the more confusing and amazing things get.

    當然啦,你看得越深,事情就越耐人尋味。

  • Diatoms are sometimes completely non-motile, but some species can also move by excreting mucus through their cell, slowly propelling themselves over a substrate.

    有些矽藻是完全不動的,有些則會藉由細胞表層分泌黏液、在培養基裡緩慢推進自己。

  • And finally, we said nothing in this entire video about the marvelous movements of prokaryotes like bacteria.

    最後說到,我們整部影片都沒有提及細菌等原核生物令人驚艷的移動方式。

  • And they have systems every bit, if not more ingenious than their more complex eukaryotic friends.

    他們也有自己的一套系統,巧妙程度和比他們還複雜的真核生物不相上下。

  • But they're also tiny... so tiny that these structures cannot be observed by microscopes like the ones we use.

    但他們實在是太迷你 … 構造小到我們使用的這台顯微鏡看不見。

  • So we just have to be content knowing that they use structures that function similarly to the structures eukaryotes use, but that are made of completely different stuff.

    所以我們只能滿足於知道他們也用功能類似於真核生物的構造,不過由完全不同的物質所組成。

  • And all of these chemical structures, eukaryotic and prokaryotic, so complex and marvelous, were selected for through billions of years of evolution.

    這些所有化學構造——真核生物和原核生物——複雜而令人驚艷,都是歷經了上百萬年的進化篩選而成。

  • And almost shockingly, just a few extremely effective systems of locomotion were uncovered.

    而且驚人的是,我們發現的還只是其中一小部分極其高效的運動系統。

  • The result... we can watch them, these little balls of chemicals working to get what they need... they are each a little soup that wants... look at them wanting.

    結果呢?我們可以觀看他們,這些小小球的化學物質努力取得所需,他們就好比一碗碗湯,饑渴地四處遊走。

  • Thank you for coming on this journey with us as we explore the unseen world that surrounds us.

    感謝你加入我們這趟旅程,一同探索我們周遭看不見的世界。

  • If you want to see more from our master of microscopes, James, check out Jam and Germs on Instagram.

    如果你想看顯微鏡大師 James 的更多作品,前往 Instagram 搜尋 Jam and Germs。

  • And if you want more from us, we've got a few videos over at youtube.com/microcosmos and we put out a new one every week.

    如果你想看更多我們的影片,歡迎前往 youtube.com/microcosmos,每個禮拜更新一次。

  • We've been doing a pretty good job of keeping on top of it.

    我們的表現一直都不錯。

  • So, thanks for liking what we do.

    感謝你喜歡我們的作品。

Now, this is a guess, because I wasn't there, and we don't have any clear records of this period of history, but at some point, in the early history of life on earth, it's very likely nothing could move.

這只是猜的,畢竟我當時不在那,而且也沒有當時的歷史記錄,但在地球生物誕生初期,很可能沒有任何東西會移動。

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B1 中級 中文 美國腔 纖毛 細胞 真核 偽足 生物 微生物

原生動物如何在環境中移動呢? (How Do Protozoa Get Around?)

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    Susan   發佈於 2020 年 03 月 26 日
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