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備註請放最後面 違者新聞文章刪除

1.媒體來源:

外媒    sciencealert

2.記者署名:

Jenny Graves, The Conversation

3.完整新聞標題:

The Y Chromosome Is Slowly Vanishing. A New Sex Gene May Be The Future of Men.

男性末日！哺乳動物有滅絕Y染色體的趨勢!

4.完整新聞內文:

The Y Chromosome Is Slowly Vanishing. A New Sex Gene May Be The Future of Men.
Humans
23 August 2024
By Jenny Graves, The Conversation
Mans Eye Staring Close Up
(Dmitry Bayer/Getty Images)

The sex of human and other mammal babies is decided by a male-determining
gene on the Y chromosome. But the human Y chromosome is degenerating and may
disappear in a few million years, leading to our extinction unless we evolve
a new sex gene.

The good news is two branches of rodents have already lost their Y chromosome
and have lived to tell the tale.

人類
2024 年 8 月 23 日
經過珍妮· 格雷夫斯《對話》
男人的眼睛凝視特寫
（德米特里· 拜爾/蓋蒂圖片社）



好消息是，囓齒類動物的兩個分支已經失去了 Y 染色體，並且還活著講述了這個故事。

A 2022 paper in Proceedings of the National Academy of Science shows how the
spiny rat has evolved a new male-determining gene.

How the Y chromosome determines human sex

In humans, as in other mammals, females have two X chromosomes and males have
a single X and a puny little chromosome called Y. The names have nothing to
do with their shape; the X stood for 'unknown'.

2022 年《美國國家科學院院刊》上的一篇論文展示了刺鼠如何演化出一種新的雄性決定
基因。

Y染色體如何決定人類性別

人類和其他哺乳動物一樣，雌性有兩條 X 染色體，雄性有一條 X 染色體和一條稱為 Y
的微小染色體。 X代表「未知」。

The X contains about 900 genes that do all sorts of jobs unrelated to sex.
But the Y contains few genes (about 55) and a lot of non-coding DNA – simple
repetitive DNA that doesn't seem to do anything.

But the Y chromosome packs a punch because it contains an all-important gene
that kick-starts male development in the embryo.

X 包含約 900 個基因，可以完成與性別無關的各種工作。但 Y 包含很少的基因（約 55
個）和大量非編碼 DNA—簡單的重複 DNA，似乎沒有任何作用。

但 Y 染色體卻具有強大的威力，因為它含有一個非常重要的基因，可以啟動胚胎中的男
性發育。

At about 12 weeks after conception, this master gene switches on others that
regulate the development of a testis. The embryonic testis makes male
hormones (testosterone and its derivatives), which ensures the baby develops
as a boy.

This master sex gene was identified as SRY (sex region on the Y) in 1990. It
works by triggering a genetic pathway starting with a gene called SOX9 which
is key for male determination in all vertebrates, although it does not lie on
sex chromosomes.

受孕後約 12 週，這個主基因會啟動其他調節睪丸發育的基因。胚胎睪丸會產生男性荷爾
蒙（睪固酮及其衍生物），確保嬰兒發育為男孩。

1990年，這個主性基因被鑑定為SRY（Y上的性別區域）。它的工作原理是觸發一條由
SOX9 基因開始的遺傳途徑，該基因是所有脊椎動物雄性決定的關鍵，儘管它並不位於性
染色體上。

The disappearing Y

Most mammals have an X and Y chromosome similar to ours; an X with lots of
genes, and a Y with SRY plus a few others. This system comes with problems
because of the unequal dosage of X genes in males and females.

How did such a weird system evolve? The surprising finding is that
Australia's platypus has completely different sex chromosomes, more like
those of birds.

消失的Y



這麼奇怪的系統是怎麼進化出來的呢？令人驚訝的發現是，澳洲的鴨嘴獸有著完全不同的

性染色體，更像鳥類的性染色體。

In platypus, the XY pair is just an ordinary chromosome, with two equal
members. This suggests the mammal X and Y were an ordinary pair of
chromosomes not that long ago.

In turn, this must mean the Y chromosome has lost 900–55 active genes over
the 166 million years that humans and platypus have been evolving separately.
That's a loss of about five genes per million years. At this rate, the last
55 genes will be gone in 11 million years.

在鴨嘴獸中，XY 對只是一條普通的染色體，有兩個相等的組成。這顯示不久前哺乳動物
的 X 和 Y 是一對普通的染色體。

反過來，這必然意味著在人類和鴨嘴獸單獨進化的 1.66 億年裡，Y 染色體失去了
900-55 個活躍基因。每百萬年大約損失五個基因。照這個速度，最後55個基因將在1100
萬年內消失。

Our claim of the imminent demise of the human Y created a furore, and to this
day there are claims and counterclaims about the expected lifetime of our Y
chromosome – estimates between infinity and a few thousand years.

Rodents with no Y chromosome

The good news is we know of two rodent lineages that have already lost their
Y chromosome – and are still surviving.

我們關於人類 Y 染色體即將滅亡的說法引起了軒然大波，直到今天，對於我們 Y 染色體
的預期壽命（估計在無窮到幾千年之間）存有支持和反對意見。

沒有Y染色體的囓齒類動物

好消息是我們知道有兩個囓齒動物譜系已經失去了 Y 染色體，但仍然存活下來。

The mole voles of eastern Europe and the spiny rats of Japan each boast some
species in which the Y chromosome, and SRY, have completely disappeared. The
X chromosome remains, in a single or double dose in both sexes.

Although it's not yet clear how the mole voles determine sex without the SRY
gene, a team led by Hokkaido University biologist Asato Kuroiwa has had more
luck with the spiny rat – a group of three species on different Japanese
islands, all endangered.

東歐的鼴鼠和日本的刺鼠都擁有一些 Y 染色體和 SRY 完全消失的物種。無論是單劑量還
是雙劑量，X 染色體都會保留。

儘管尚不清楚在沒有SRY基因的情況下鼴鼠如何決定性別，但由北海道大學生物學家
Asato Kuroiwa領導的研究小組在刺鼠身上取得了更多的運氣—刺鼠是分佈在日本不同
島嶼上的三個物種，全部瀕臨滅絕。

Kuroiwa's team discovered most of the genes on the Y of spiny rats had been
relocated to other chromosomes. But she found no sign of SRY, nor the gene
that substitutes for it.

In 2022 they published a successful identification in PNAS. The team found
sequences that were in the genomes of males but not females, then refined
these and tested for the sequence on every individual rat.

黑岩的研究團隊發現，多刺大鼠 Y 染色體上的大部分基因已被重新定位到其他染色體。
但她沒有發現 SRY 的跡象，也沒有發現替代它的基因。

2022年，他們在《PNAS》上發表了成功的鑑定結果。研究小組發現了雄性而非雌性基因組
中的序列，然後對這些序列進行了改進，並在每隻老鼠身上測試了該序列。

What they discovered was a tiny difference near the key sex gene SOX9, on
chromosome 3 of the spiny rat. A small duplication (only 17,000 base pairs
out of more than 3 billion) was present in all males and no females.

They suggest this small bit of duplicated DNA contains the switch that
normally turns on SOX9 in response to SRY. When they introduced this
duplication into mice, they found that it boosts SOX9 activity, so the change
could allow SOX9 to work without SRY.

他們發現，多刺大鼠第 3 號染色體上的關鍵性基因 SOX9 附近有微小差異。所有男性中
都存在少量重複（超過 30 億個鹼基對中只有 17,000 個鹼基對），而女性中沒有。



What this means for the future of men

The imminent – evolutionarily speaking – disappearance of the human Y
chromosome has elicited speculation about our future.

Some lizards and snakes are female-only species and can make eggs out of
their own genes via what's known as parthenogenesis. But this can't happen in
humans or other mammals because we have at least 30 crucial "imprinted" genes
that work only if they come from the father via sperm.

這對男性的未來意味著什麼

從演化的角度來說，人類 Y 染色體即將消失引發了人們對我們未來的猜測。



To reproduce, we need sperm and we need men, meaning that the end of the Y
chromosome could herald the extinction of the human race.

The new finding supports an alternative possibility – that humans can evolve
a new sex determining gene. Phew!

為了繁衍，我們需要精子，我們需要男人，這意味著Y染色體的末端可能預示著人類的滅
絕。


more than one new system evolves in different parts of the world?

A "war" of the sex genes could lead to the separation of new species, which
is exactly what has happened with mole voles and spiny rats.

然而，新的性別決定基因的演化也伴隨著風險。如果世界不同地區出現多個新系統怎麼辦
？

性基因的「戰爭」可能導致新物種的分離，這正是鼴鼠和刺鼠所發生的情況。

So, if someone visited Earth in 11 million years, they might find no humans
– or several different human species, kept apart by their different sex
determination systems.The Conversation

Jenny Graves, Distinguished Professor of Genetics and Vice Chancellor's
Fellow, La Trobe University

因此，如果有人在 1100 萬年後訪問地球，他們可能會發現沒有人類，或者發現幾個不同
的人類物種，由於不同的性別決定系統而被隔開。對話

Jenny Graves ，拉籌伯大學遺傳學傑出教授兼副校長研究員

5.完整新聞連結 (或短網址)不可用YAHOO、LINE、MSN等轉載媒體:

https://reurl.cc/XRLDlR

6.備註:

結束了，以後沒有男娘跟正太了。男生要好好保護自己。

https://youtu.be/VNl4J9b_xhE

只有百合的世界也不錯吧？

https://youtu.be/9gXh8VOfQT4

鴨嘴獸真的是很邪門的生物...


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※ 作者: STAV72 2024-08-23 18:37:41
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