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这种鱼的眼睛就像实时的Photoshop – 译学馆
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这种鱼的眼睛就像实时的Photoshop

Baby Zebrafish Eyes Work Kind of like Real-Time Photoshop

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斑马鱼基本上像是水生实验室的老鼠
Zebrafish are basically aquatic lab rats.
它们是科学家用于研究的典型生物体
They’re a model organism that scientists use to study everything
从发育到疾病
from development to disease,
放置在仔细控制环境的鱼塘中
in the carefully controlled environment ofa fish tank.
现在 研究人员也在调查这些小的
Now, researchers are also looking into how these small,
有条纹的鲦鱼是如何视物的
stripy minnows see,
他们上周在《当代生物学》杂志上发表了一篇相关论文
and they published a paper about it last week in the journal Current Biology.
这个研究第一次详细描述
This study is the first detailed description of
有四种感光细胞的脊椎动物
how vision works in a vertebrate
的视力如何工作
that has 4 kinds of color photoreceptors,
不像人只有极少的三种
not a measly 3 like humans.
他们发现
And they found that,
这些小鱼像婴儿一样 有相当精确的视力
as babies, these tiny fish have really precise vision that’s
不光是我们的肉眼所见
more than meets the eye.
事实上 它把环境裁剪成不同的部分
In fact, it’s tailored to the differentparts of their environment.
斑马鱼通常发现于亚洲清澈的缓流中
See, zebrafish are naturally found in clear,slow-moving water in Asia.
他们依靠眼睛在周围找路
They rely on their eyes to find their way around,
捕食 并避免被吃掉
hunt, and avoid getting eaten.
斑马鱼宝宝好像身上全是眼睛
And baby zebrafish are like all eyes
它们的眼球占据了整个身体的四分之一
their eyeballs make up a quarter of the total volume of their bodies
包含中枢神经系统一半的神经元
and contain half of the neurons in their central nervous system.
如果婴儿有相同比例
If our babies had similar proportions,
他们的眼睛会有柚子那么大
their eyes would be like grapefruit sized.
研究重点在视网膜
This research focused on the retina,
在眼球的后面
which is in the back of the eyeball
光敏感的感光细胞在的地方
where light-sensitive photoreceptors are found.
有两种主要的感光细胞
There are two main types of photoreceptor cells:
视杆细胞能在弱光下视物
rods detect low levels of light
但不能辨别颜色
but don’t really detect color
视锥细胞在强光中工作更好
and cones work better at bright levels of light
但是可以辨别颜色
but can detect color.
人类视网膜中 视杆细胞和视锥细胞均匀分布
In human retinas, rods and cones are pretty evenly distributed,
除了一个叫做中央凹的区域
except for a region called the fovea
有更多视锥细胞并且视觉更敏感
where there are more cones and our vision is a little sharper.
斑马鱼宝宝的视网膜更加复杂
But baby zebrafish retinas are more complicated.
人类视网膜有三种视锥细胞
While human retinas have 3 types of cones
一种对光的红波长敏感
one sensitive to red wavelengths of light,
一种对光的绿波长敏感 还有一种对蓝波长敏感
one to green, and one to blue
斑马鱼有第四种细胞对紫外光敏感
zebrafish have a fourth that’s sensitive to UV light.
在它们的眼睛里 不同的感光细胞
And in their eyes, different photoreceptors are concentrated
会在最需要它们的时侯集中
where they’re needed most.
斑马鱼宝宝在浅水域活动时
Baby zebrafish hang out in shallow water
死亡经常来自水面之上
where death typically comes from above,
无论是苍鹭还是其他掠食者的轮廓映衬在明亮的天空中
whether it’s a heron or other predator silhouettedagainst the bright sky.
所以从上方获得光线的视网膜部分
So the part of the retina that gets light from above
有更多视杆细胞
has more rods,
因为它们只需观察是否有物体靠近
because they just need to see if anything is coming
而不需要看到颜色
not what color it is.
大多数彩色的东西 比如礁石 植物
where light-sensitive photoreceptors are found.
都在斑马鱼宝宝的前面或者下方
are in front of or below baby zebrafish.
因此这些视网膜区域有更多视锥细胞
So those areas of the retina have more cones,
尤其对红光 绿光 蓝光敏感
especially the ones sensitive to red, green, and blue light
但斑马鱼宝宝吃的单细胞微生物是透明的
But the single-celled microorganisms thatbaby zebrafish eat are translucent,
视锥细胞很难发现它们
which makes them hard to see with those cones.
除非微生物反射大量紫外线
Except they do reflect a good amount of UV light.
从冲击区获得光线的部分视网膜
So the parts of the retina getting light from the strike zone,
只是研究者为研究鱼视野使用的一个名词
which is just a cool term researchers use for the horizon of the fish’s vision,
它有更多对紫外光敏感的视锥细胞
have more cones sensitive to UV light.,
这些视网膜主要收集世界信息
Basically all these retinal regions chunk up the world,
影像的不同部分
so different parts of the image
增加颜色或者形成对照
have boosted color or contrast
像对世界的实时的图像处理
like Photoshop manipulation of the world in real time.
这在帮助它们存活上起很大作用
And this probably plays a big role in helping them survive,
否则它们不会进化至此
otherwise they wouldn ’ t have evolved to be this way.
当斑马鱼宝宝成熟
When baby zebrafish mature, though,
它们眼睛成长 向更深的水域运动
they grow into their eyes, move into deeper water, and
丢失一些视觉的超能力
kind of lose their vision superpowers.
它们的视网膜变的更接近人类
Their retinas change to be more like ours,
不同的视锥细胞重新均衡分布
where different cones are redistributed in a more even pattern.
不是所有的鱼都有好视力
But not all fish have good eyesight!
小鲸鱼听起来像一个浴缸玩具
The baby whale fish sounds like a poorly named bathtub toy,
我猜应该是短粗的 可爱的 鲸鱼样的
and I guess it’s kind of stubby and cute and whale-like.
但是不像斑马鱼 它在非洲中部
But unlike zebrafish, it lives in muddy rivers
能见度低的泥泞的河流生活
in Central Africa where visibility isn’t so great.
不需依靠眼睛 它使用电力来感知周围
So instead of relying on its eyes, it uses electricity to get around.
根据上周发表在
And according to new research published
《当代生物学》杂志的新文章
in the journal Current Biology last week,
我们知道这些鱼如何使用电力
knowing how these fish use electricity
可能会让我们洞悉一些严重的人类疾病
may give us some insight into some serious human diseases.
数个品种的鱼用电力来交流
Several species of fish use electricity to communicate
感知周围 像回声定位
and sense what’s nearby, kind of like echolocation.
为了做到这点
And to do that,
他们有特殊的发电细胞组成的电力器官
they have electric organs with specialized cells called electrocytes,
像肌肉细胞和神经细胞可以产生动作电位
which can generate action potentials likemuscle cells and nerve cells.
动作电位发生在
Action potentials occur
离子快速通过细胞膜 改变电荷
when ions rapidly cross some membranes and alter the electrical charge and
一群发电细胞同时作用时
when a whole bunch of electrocytes do this simultaneously,
他们可以放电
they can emit an electrical discharge.
但离子不是能够穿越所有细胞膜
But ions can’t cross the cell membrane just anywhere.
它们需要穿过特殊蛋白离子通道
They have to pass through special proteins called ion channels,
像是仔细控制的门
which are like carefully controlled doors.
小鲸鱼可以产生
Now, baby whale fish can generate
极快的电子脉冲
extremely quick electric pulses
只有万分之二秒长
that are only 2 ten thousandths of a second long.
它们须保持脉冲在短时间内完成
They have to keep it short
才能躲避鲶鱼
so they can stay hidden from catfish,
鲶鱼可以感受到电力 并吃掉小鲸鱼
which can also sense electricity and will totally eat them.
研究者想知道
So these researchers wanted to know
小鲸鱼如何产生这些极短的动作电位
how baby whale fish make these extremely short action potentials,
所以他们仔细观察KCNA7钾离子通道
so they took a closer look at the KCNA7 potassium ion channel.
人类在心脏和肌肉组织有相似的蛋白
Humans have this same protein in our heart and muscle tissues,
但小鲸鱼有轻微的不同
but the baby whale fish has a slightly different version.
研究者在鱼的离子通道发现一种
The researchers discovered a negatively charged patch of amino acids
带负电荷的氨基酸
in the fish’s ion channel
这使它变得更敏感 并且更快地开放
that makes it more sensitive and able to open more quickly.
明白离子通道的不同如何影响工作
Understanding how slight differences in these ion channels affect how they work
可能帮助科学家治疗像癫痫
might someday help scientists treat diseases like epilepsy,
心律失常 和肌肉紊乱之类的疾病
and certain heart rhythm and muscle disorders.
这些情况联合基因突变
These conditions are linked with genetic mutations
也可以改变钾离子通道的工作
that also change how potassium ion channels work.
因此了解这种奇怪的小鱼能帮助科学家找到方向
So maybe understanding this odd little fish will help scientists find a fix.
感谢观看这集充满鱼的科普新闻
Thanks for watching this fish-filled episode of SciShow News!
如果你喜欢关注
If you’d like to stay up to date
最新的科学研究
on the latest research in all fields of science,
从水生脊椎动物到人类医学 我们每周五出新的新闻剧集
from aquatic vertebrates to human medicine, we post these News episodes every Friday!
或者你想随便看看
Or you can stick around
我们已经上传的上百个视频
for all of our videos including the hundreds we’ve already uploaded
可以在youtube网或SciShow上订阅
at youtube.com/SciShow where you can subscribe.
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斑马鱼有着特殊的眼睛,像是实时的Photoshop,它们视物的原理可以帮助人们解决许多科学问题

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