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你的狗多大了?我是说换算成人生的话

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2019年11月20日

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No one knows how it started, or where it came from, but the idea that you can convert your dog's age to human years by multiplying by seven? Total myth. But we like to contextualise our animal companions' ageing against our own lives; if nothing else, it helps us to relate to them.

没有人知道它是怎么开始的,也不知道它是从哪里来的,但是你可以通过乘以7把狗的年龄换算成人类的年龄?完全是神话。但是,我们喜欢把动物同伴的衰老与我们自己的生活联系起来;如果没有别的东西,它会帮助我们与它们联系起来。

Finding an accurate way to do so isn't easy, but a team of researchers has developed a formula. And it's based not on some arbitrary metric, but on changes to DNA over time; they've described it in a paper published on the pre-print resource bioRxiv ahead of peer review.

找到一种精确的方法并不容易,但一组研究人员已经开发出一种公式。它不是基于任意的度量,而是基于DNA随时间的变化;他们在同行评审之前发表在pre-print resource bioRxiv上的一篇论文中对此进行了描述。

The team's method is based on an epigenetic mechanism called methylation. As both humans and domestic dogs (Canis lupus familiaris) age, methyl groups are added to our DNA molecules, which can change the activity of a DNA segment without altering the DNA itself.

研究小组的方法基于一种称为甲基化的表观遗传机制。随着人类和家犬(犬类狼疮)的衰老,甲基被添加到我们的DNA分子中,它可以改变DNA片段的活性而不改变DNA本身。

你的狗多大了?我是说换算成人生的话

This obviously has its own function, but one corollary is that DNA methylation can be used to measure age in humans. This is called the epigenetic clock.

这显然有它自己的功能,但一个推论是DNA甲基化可以用来测量人类的年龄。这被称为表观遗传钟。

So, led by geneticists Tina Wang and Trey Ideker of the University of California San Diego, the researchers set out to compare the epigenetic clock of humans to the epigenetic clock of dogs.

因此,由加州大学圣地亚哥分校的遗传学家蒂娜•王和特雷•艾德克领导,研究人员开始将人类的表观遗传时钟与狗的表观遗传时钟进行比较。

Dog lifespans can vary wildly: from 6-7 years for some large breeds such as mastiffs to as many as 17-18 years for dogs such as chihuahuas. Despite this variation, all dogs exhibit a similar developmental, physiological, and pathological trajectory.

狗的寿命可以有很大的差异:从一些大型犬种(如獒犬)的6-7岁到吉娃娃犬的17-18岁不等。除了这些变异,所有的狗都表现出相似的发育、生理和病理轨迹。

A single breed offers strong genome homogeneity, which increases the chance of identifying genetic factors associated with complex traits including ageing, the team said. So they used Labrador retriever dogs for this study.

研究小组称,单一品种具有很强的基因组同质性,这增加了识别与包括衰老在内的复杂性状相关的遗传因素的机会。所以他们用拉布拉多寻回犬做了这项研究。

They then compared their dog data to the published methylation profiles from the blood of 320 humans, aged between one and 103 years, and those of 133 mice.

然后,他们将狗的数据与320名年龄在1岁到103岁之间的人以及133只老鼠的血液甲基化谱进行了比较。

"Using targeted sequencing, we characterise the methylomes of 104 Labrador retrievers spanning a 16 year age range, achieving >150X coverage within mammalian syntenic blocks," they wrote in their paper.

他们在论文中写道:“通过靶向测序,我们对104只拉布拉多猎犬的甲基体进行了鉴定,它们的年龄跨度为16岁,在哺乳动物的共济区内覆盖率超过150倍。”。

"Comparison with human methylomes reveals a nonlinear relationship which translates dog to human years, aligns the timing of major physiological milestones between the two species, and extends to mice."

“与人类甲基体的比较揭示了一种非线性关系,这种关系将狗的年龄转化为人的年龄,将两个物种之间的主要生理里程碑的时间安排对齐,并延伸到老鼠身上。”

The similarities were the greatest when comparing young dogs to young humans, and elderly dogs to elderly humans.

当比较幼犬和幼犬,老年犬和老年人时,相似性最大。

This matching of the epigenetic clocks allowed the team to derive a formula for calculating the 'human' age of dogs: human_age = 16ln(dog_age) + 31.

这种表观遗传时钟的匹配使得研究小组可以推导出一个计算狗的“人类”年龄的公式:human_age = 16ln(dog_age) + 31。

你的狗多大了?我是说换算成人生的话

So, multiply the natural logarithm of your dog's age in years (here's a calculator you can use) by 16, then add 31. That will give you the dog's age in 'human years'.

所以,用你的狗的年龄的自然对数乘以16(这是一个你可以使用的计算器),然后加上31。这样你就能知道狗狗的年龄了。

Using this formula, certain milestones matched up really well. Seven weeks in dogs was found to correspond with nine months in humans - the time when baby teeth are erupting in puppies and infants. The two species' average lifespans also matched up - 12 years for the Labradors, and 70 for humans.

使用这个公式,某些里程碑匹配得非常好。研究发现,狗的7周相当于人类的9个月——幼犬和婴儿的乳牙长出的时间。这两个物种的平均寿命也相当——拉布拉多犬12岁,人类70岁。

That said, other milestones didn't match up quite so well. Dogs, for instance, go through puberty and reach sexual maturity faster than humans, so the period between adolescence and middle age doesn't match up - a five-year-old Labrador is calculated at around 56 in human years. But dog methylation slows down as they age, so humans can catch up.

也就是说,其他的里程碑并不匹配得那么好。例如,狗经历青春期和性成熟的速度比人类快,所以从青春期到中年这段时间是不匹配的——一只5岁的拉布拉多按人类年龄计算大约是56岁。但是随着年龄的增长,狗体内的甲基化作用会逐渐减缓,所以人类可以迎头赶上。

And, of course, there's that pesky problem with different breeds ageing differently. So we'll probably never have a one-size-fits-all approach - but a formula based on the epigenetic clock is considerably more useful than simply multiplying by seven.

当然,不同品种的狗衰老的方式也不一样。因此,我们可能永远不会有一种放之四海而皆准的方法,但基于表观遗传时钟的公式要比简单地乘以7有用得多。

The team's research has been published on bioRxiv.

该团队的研究已经发表在bioRxiv上。


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