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Kaguya the Mouse, High school

A white lab mouse held in a scientist’s gloved hand

A baby mouse usually comes from one egg and one sperm. Scientists in Tokyo tried to grow a mouse from the DNA of two mouse eggs and no sperm.

Could two eggs and no sperm ever make a living mouse?

2 eggs can make a mouse, with some help

In 2004, scientists in Japan reported a mouse named Kaguya, made from two eggs and no sperm. Some genes carry a tag that says which parent they came from, so two eggs alone cannot make a mouse. One egg came from a newborn mouse whose tags weren’t on yet. That mouse came from a line of mice born missing the piece of DNA that holds the switch for a growth gene.

The head and face of a 13-day-old mouse embryo under a microscope
A printing press presses inked letters onto paper. Print comes from an Old French word meaning “to press.”

Your word of the day is

im-PRIN-ting

im-in, into, onfrom Latin in-
printto pressfrom Latin premere
-ingthe action or processfrom Old English -ing

In genetics, a tag on a gene that marks which parent the gene came from. The tag controls whether that copy of the gene switches on.

A scientist in a lab coat looks through a microscope

Eggs and sperm carry the same genes, yet embryos made from two ordinary eggs stop growing.

Which chain of events explains why a two-egg embryo stops growing?

A model of the twisted DNA double helix

Kaguya’s DNA came from the eggs of two different female mice, a newborn and an adult.

Each of the two eggs gave Kaguya ____ of a full set of chromosomes.

A scientist holds up a glass jar with a lab mouse inside

What would a clone of the adult mouse carry?

Black-and-white video of a small house mouse sniffing around in the corner of a wall

About 70% of Prader-Willi cases come from a missing piece of dad’s chromosome 15, and about 25% from two copies of mom’s chromosome 15.

How can two different causes both lead to Prader-Willi syndrome?

Close-up video of a brown mouse with big ears sitting in a ceramic dish, nibbling sunflower seeds

Kaguya’s team made about 460 tries, which gave 10 live pups and one adult mouse.

Out of about 460 tries to make Kaguya, ____ gave a live pup.

Video of a scientist in a lab placing and studying a specimen slide under a microscope

Out of about 460 tries to make Kaguya, ____ gave an adult mouse.

Video of a scientist's gloved hand using a pipette to load samples into a gel for a DNA experiment

About 460 tries gave 10 live pups and one adult mouse, Kaguya.

What do Kaguya’s success rates say about using the two-egg method in people in 2004?

Animation of a glowing golden DNA double helix slowly turning against a dark blue background

Kaguya’s embryo needed an egg from a newborn mouse, and that egg was missing the growth gene switch.

Why would Kaguya’s two changes block the two-egg method in people?

Several white mice in a cage, one sitting inside a round metal food dish

Claim, evidence, reasoning

Coquita’s baby had no father and lost most of Coquita’s mixed gene pairs. Kaguya had no father either.

Which claim about Kaguya’s gene versions has the best support?

Two lab mice on a purple-gloved hand: a brown gene-knockout mouse beside a normal black lab mouse

Claim, evidence, reasoning

Which evidence backs the claim that Kaguya got a new mix of gene versions?

Black-and-white photo of a woman scientist in a lab coat looking at a white mouse inside a labeled glass jar

Claim, evidence, reasoning

Which reasoning connects Kaguya’s DNA from two different mice to a new mix of gene versions?

A white mother mouse curled over her nursing babies inside a small wooden house lined with straw

A switch blocks the growth gene unless it carries a dad tag from sperm. In 1995, Princeton mice that got a missing growth gene switch from their mother were 27% heavier than mice that got the missing switch from their father.

Why were the Princeton mice heavier when the missing growth gene switch came from their mother?

A big litter of pink newborn baby mice piled together in a straw nest

The Princeton mice and Kaguya both come from experiments on gene tags in mice.

Which question about gene tags do the Princeton and Kaguya mouse studies leave open?

A brown wild mother mouse with several young mice gathered under her among fallen leaves

Eggs and sperm carry the same genes. Only sperm add the dad tag that lets the growth gene switch on.

How does imprinting of the growth gene show why a mouse needs DNA from both an egg and a sperm?

Several sandy-brown mice with big ears huddled together in a nest of dry leaves

Lesson complete

Today’s word

imprinting

im-PRIN-ting

In genetics, a tag on a gene that marks which parent the gene came from. The tag controls whether that copy of the gene switches on.

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Up nextadenosineCoffee and Your Brain
Sources
  1. Tomohiro Kono and colleagues, Tokyo University of Agriculture, Nature, 2004
  2. Philip Leighton, Shirley Tilghman and colleagues, Princeton University, Nature, 1995
  3. Andrew Keniry, Wolf Reik and colleagues, Nature Cell Biology, 2012
  4. Yayoi Obata, Tomohiro Kono and colleagues, Development, 1998
  5. Manabu Kawahara, Tomohiro Kono and colleagues, Nature Biotechnology, 2007
  6. Yanchang Wei, Cai-Rong Yang and Zhen-Ao Zhao, Shanghai Jiao Tong University and UC San Francisco, PNAS, 2022
  7. Review by Denise Barlow and Marisa Bartolomei, Cold Spring Harbor Perspectives in Biology, 2014
  8. MedlinePlus Genetics, US National Library of Medicine, Prader-Willi, Angelman, Beckwith-Wiedemann
  9. Helen Pearson, “Mouse created without father”, Nature News, April 22, 2004
  10. John Travis, “Two egg cells make fatherless mouse”, Science News, May 2004
  11. Vision and Change core concepts and competencies, as summarized in Brownell and others, CBE Life Sciences Education, 2014
  12. Word origins from Dictionary.com: imprinting, imprint, in-, print, -ing, genome, press, pressure, impression, impressionism, espresso
  13. Spanish and French words from Wiktionary: imprimir, imprimer