mouse-biology

Scientists are one step closer to understanding the genetic difference between human and chimpanzee brain development. They isolated a stretch of DNA, once thought to be “junk”, near a gene that regulates brain development. Then they added that DNA – either the human or the chimp version – to mouse embryos. Lo and behold, the mouse brains with human DNA were 12% bigger than mouse brains with chimpanzee DNA.

Eventually, work like this could generate a list of DNA sequences that give a brain some capabilities that are characteristically human. That could be important for understanding what goes wrong in diseases of the brain.

As for the ethics of such experiments:

An experiment like this recent one is not going to create mice that talk and think like people. But it could be more ethically worrisome to try to genetically enhance the brains of nonhuman primates or other reasonably intelligent animals — like pigs.

Full story, from Nell Greenfieldboyce, here.

Image: Silver Lab/Duke University

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Our DNA is 99.9% the same as the person sitting next to us.

Physicist Riccardo Sabatini recently demonstrated a printed version of your genetic code would fill 262,000 pages, or 175 big books.

Large amounts of genetic code are used for similar biological mechanisms that are the same across many species. Here’s other genetically similar species.

(Business Insider)

Peripheral nerves of a mouse embryo

Unlike the brain and spinal cord that are housed in protective bone, peripheral nerves connect regions of the body to the central nervous system like telephone cables. Peripheral nerves relay movement information from the brain to the muscles, for example, or sensory information from the skin to the brain. Remarkably, and also different from the brain and spinal cord, peripheral nerves have a tremendous capacity to regenerate when injured. Severed peripheral nerves grow about 1 mm per day (about an inch per month) until the two severed ends reconnect and innervate a once paralyzed muscle.

Image by Zhong Hua, Johns Hopkins University School of Medicine.

Multiphoton Microscopy of Mouse Motor Neurons

Motor neurons in the sternomastoid muscle of a postnatal day 9 mouse which constitutively express cytoplasmic CFP and YFP in varying proportions under the thy1 promoter. Acetylcholine receptors are labeled with alpha-bungarotoxin-Alexa-647. Imaged with ZEISS LSM 780 NLO. 

Image Courtesy: Stephen Turney, MCB, Harvard University.

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Expression of combinations of three different fluorescent proteins in a mouse brain produced ten different colored neurons. Individual neurons in a mouse brain appear in different colors in a fluorescence microscope. This “Brainbow” method enables many distinct cells within a brain circuit to be viewed at one time. 

How exciting for them!

First rodent found with a human-like menstrual cycle

Mice are a mainstay of biomedical research laboratories. But the rodents are poor models for studying women’s reproductive health, because they don’t menstruate.

Now researchers at Monash University in Clayton, Australia, say that they have found a rodent that defies this conventional wisdom: the spiny mouse (Acomys cahirinus). If the finding holds up, the animal could one day be used to research women’s menstruation-related health conditions.

“When you do science you’re not surprised at anything — but wow, this was a really interesting finding,” says Francesco DeMayo, a reproductive biologist at the US National Institute of Environmental Health Sciences in Research Triangle Park, North Carolina, who was not involved in the work.

The study, which was posted to bioRxiv preprint server on 3 June1, involved 14 female spiny mice. The researchers found that the animals averaged a 9-day menstrual cycle and spent 3 days — or 20–40% of their cycle — bleeding. This ratio is similar to that in women, who typically bleed for 15–35% of their 28-day cycle.

Bellofiore, N. et al. Preprint at bioRxiv http://dx.doi.org/10.1101/056895 (2016).

The spiny mouse averages a 9-day menstrual cycle. fotandy/Getty

A section through a mouse vertebra at 200x magnification

The vertebrae that make up our spine have the critical task of housing and protecting the spinal cord, a thin bundle of nervous tissue hooked up directly to the brain. The spinal cord in part transmits movement information from the brain to the muscles. In fact, the function of the spinal cord can be divided into segments based on the muscles they control: Nerves from the lower vertebrae in the neck help extend the elbows and flex the wrists, while nerves from the lower back vertebrae assist in extending the legs and toes. Spinal cord injury can result in different degrees of paralysis depending on which segment was affected.

Image by  Dr. Michael Nelson and Samantha Smith, University of Alabama at Birmingham.

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Confocal microscopy of a mouse brain cortex

Depth coded projection (color) image of mouse hippocampus sections of thy1-GFP line. Stained with GFP and imaged with ZEISS ELYRA PS.1 with LSM 780 confocal option. Tiling & stitching with ZEN software generates hi-res confocal maps, make sure to download in full resolution and zoom in.

Sample courtesy of Yi Zuo, Molecular, Cell and Developmental Biology (MCDB) department, University of California Santa Cruz.

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Oculomotor nerve

WHAT’S THAT?
The oculomotor nerve controls the eye muscles that allow our pupils to focus light, eyelids to blink, and eyes to track moving objects. The bundle of oculomotor nerves in this image is from a Brainbow mouse, which was genetically engineered to randomly color neurons different hues.

WHAT’S THE LATEST?
Some brain injuries like concussions can be difficult to diagnose quickly in an emergency room or on the sidelines of sports. Recently, researchers at NYU Langone Medical Center developed a new technology that uses eye tracking as a readout for brain injury. They tracked the eye movements of healthy and brain-injured patients as they watched music videos (including “Under the Sea” from The Little Mermaid and Shakira’s “Waka Waka”) and could accurately diagnose brain injury and severity. While the study was small, they hope larger studies will make the technology more sensitive and will help validate other brain injury tests.

Image by Dr. Katie Matho, Dr. Jean Livet, and Raphaëlle Barry/Nikon Small World.

03 March 2014

Blue Gene Baby

Like all life, this mouse embryo is a result of the blueprint that lies in its DNA. But unlike normal mice, it’s also a literal print in blue of one part of this genetic building plan: the dark spots show where a specific ‘regulatory element’ of the DNA was active. These elements turn gene activity up or down, influencing how much protein is made. This way all the right parts of the body are built in all the right places. You can’t normally see regulatory elements at work, so scientists have done something special here to make the blue spots appear. They hooked up the regulatory element to a bacterial gene whose product turns an added chemical blue. Armed with this technique researchers are delving further into how DNA blueprints build bodies, and where things go wrong in developmental diseases.

Written by Emma Bornebroek

Image courtesy of Vahan Indjeian and colleagues
MRC Clinical Sciences Centre
Copyright held by original authors

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Stem cell technique makes sperm in a dish

Scientists in China have finally succeeded in creating functioning sperm from mice in the laboratory. To accomplish this feat, the researchers coaxed mouse embryonic stem cells to turn into functional sperm-like cells, which were then injected into egg cells to produce fertile mouse offspring. The work, reported February 25 in Cell Stem Cell, provides a platform for generating sperm cells that could one day be used to treat male infertility in humans.

Quan Zhou, Mei Wang, Yan Yuan, Xuepeng Wang, Rui Fu, Haifeng Wan, Mingming Xie, Mingxi Liu, Xuejiang Guo, Ying Zheng, Guihai Feng, Qinghua Shi, Xiao-Yang Zhao, Jiahao Sha, Qi Zhou. Complete Meiosis from Embryonic Stem Cell-Derived Germ Cells In Vitro. Cell Stem Cell, 2016; DOI: 10.1016/j.stem.2016.01.017

This graphical abstract shows how Zhou et al. generated haploid male gametes from mouse embryonic stem cells that can produce viable and fertile offspring, demonstrating functional reproduction of meiosis in vitro. Credit: Zhou, Wang, and Yuan et al./Cell Stem Cell 2016

Inner ear of a mouse

One of the most common genetic defects in human deafness is the disappearance of an important family of proteins: the claudins. Claudins are the most critical component of tight junctions (shown here in blue), the place where two adjacent cells meet. Imagine a tight circle of people linking arms to protect what’s inside; tight junctions are what protect a tissue from unwanted molecules or cells trying to pass through. When mice cannot make claudin, the tight junctions in the cochlea (the spiral-shaped portion of the inner ear) are disrupted, robbing them of their hearing sensitivity.

Image by Dr. Alexander Gow and Cherie Southwood, Wayne State University.

A group called The Turning Point Project took out this full-page ad in the New York Times in 1999 after the publication of a paper including the image of Joseph Vacanti’s “earmouse.” The ad falsely claims that the mouse is a result of genetic engineering and includes the following criticisms of biotechnology:

“Does anyone think that it’s shocking, therefore, that this infant biotechnology industry feels it’s okay to capture the evolutionary process and to reshape the life on earth to suit its balance sheets?”

“Biotech companies are blithely removing components of human beings (and other creatures) and treating us all like auto parts at a swap meet.”

“Someday when one of these companies finally decides the public mood is receptive, will they make a human-gorilla combo to take care of heavy labor?”

“Have we lost our sanity?” 

So far, there exist no half-human, half-animal “chimeras” (like mermaids or centaurs) but we may soon have them”

Sometimes scientists are so focused on results that they forget about ethics, and it’s great that public groups are out there to focus on holding the labs accountable.

But, as you can see, in a lot of cases the accusers come off as rather phobic of change and science-illiterate. 

From ZEISS Microscopy’s flickr, “Confocal microscopy of mouse brain, cortex, detail”

“Depth coded projection (colour) image of mouse hippocampus sections of thy1-GFP line. Stained with GFP and imaged with ZEISS ELYRA PS.1 with LSM 780 confocal option. Tiling & stitching with ZEN software generates hi-res confocal maps, make sure to download in full resolution and zoom in. Sample courtesy of Yi Zuo, Molecular, Cell and Developmental Biology (MCDB) department, University of California Santa Cruz. www.zeiss.com/elyra”