Light enters eyes and is transmitted to SCN and PHb.

Light: A Happy Pill for Dark Days?

Have you ever had a day where you feel exceptionally good? As in take on the world kind of good? You feel so much better than the previous couple of days that you stop to wonder why.

Then it dawns on you.

The sun is out. It’s been cloudy for the past week but now—SUNSHINE.

You go out to lunch or for a walk just to take in those rays. Sure, it feels warmer than your darkened office space, but it’s the light rather than warmth that’s making a difference.

You purposely don’t wear sunglasses and it feels like the light is coming in through your eyes and massaging that part of your brain that is your happy zone. Are you imagining it or is the sun really affecting how you feel?

In a study reported in the September 2018 issue of Cell we learn that this is not a figment of your or my imagination (1). There is, in fact, a type of retinal cell that transports sunlight directly to the part of our brains that affects mood.

Eyes and the Body’s Master Clock

Circadian rhythms are innate time-keeping functions found in all multicellular organisms. This subject of the 2017 Nobel prize in Physiology or Medicine, circadian rhythms are fueled by daily light-dark cycles and are critical to the function of neurologic, immune, musculoskeletal and cardiac tissues (2). Nearly every mammalian cell is affected by circadian rhythms.

The human body has a circadian master clock, the suprachiasmatic nucleus or SCN. The SCN is a highly innervated tissue located in the hypothalamus (see image). It is connected directly to the retina by the optic nerve, and thus is influenced by external light and dark.

Light enters eyes and is transmitted to SCN and PHb.
Light enters the eyes and affects the SCN (physiologic effects), and as discussed in recent research, Fernandez et al. here, the perihabenular nucleus (behavioral effects). (Image in public domain.)

The retina of the eye is the light gathering instrument for this organ. Historically, it’s been understood that the retina is composed of two cell types, rods and cones, that function in transmitting light and images to the optic nerve, which sends those signals to the brain.

Drawing of the retina with rods and cones, some nervous tissues.
Some parts of the retina. Light enters the eye (from left) and passes through to the rods and cones. Here a chemical change converts the light to nerve signals. Image based on drawing by Ramón y Cajal, 1911 and licensed under Wikimedia commons.

Studies by Hattar et al. in the early 2000s identified that another cell found in the retina, the melanopsin-containing intrinsically photoactive retinal ganglion cells (ipRGCs) as the transmitter of circadian light signals (3). Through this direct connection to the SCN, the circadian master clock, the ipRGCs can influence a wide range of light-dependent functions independent of image processing (4).

Now Fernandez et al. have identified multiple types of ipRGCs. They showed that ipRGCs that mediate the effects of light on learning work via the SCN, while the pathway for light influencing emotions is different.

They discovered a new target of ipRGC cells, the perihabenular nucleus (PHb). The PHb is a newly recognized thalamic region of the brain. The authors showed that the connection between light and mood is regulated by ipRGCs through the PHb versus the SCN. They show that the PHb is integrated into other mood-regulating centers of the thalamic region.

You can see the details of their studies here.

In Conclusion

Daylight, and lack thereof, does affect both our mood and our ability to learn. In this 2018 report, we have learned that the pathways for these effects are distinct, and gain an understanding of a new thalamic region by which the light and mood actions occur. This information could influence development of better drugs and/or therapies for major depressive disorders.

For those of us with seasonal affective disorder, the evidence is undeniable—lack of light can cause issues, from sleep-wake problems, to mood and learning issues.

And while we can’t create sunshine, a special lamp or light box may help to gain some full spectrum light. To learn more about how to choose such a lamp and when to use it, see this Mayo clinic article for details.

References

  1. Fernandez, D.C. et al. (2018) Light affects mood and learning through distinct retinal pathways. Cell 175, 71–84.
  2. Ledford, H. and Callaway, E. (2017) Circadian clock scoops Nobel prize. Nature 550, 18.
  3. Hattar, S. et al. (2002) Melanopsin-containing retinal ganglion cells: architecture, projections, and intrinsic photosensitivity. Science 295, 1065–70.
  4. Hattar, S. et al. (2003) Melanopsin and rod-cone photoreceptive systems account for all major accessory visual functions in mice. Nature 424(6944)76–81.

4 Things We Recently Learned About Cats

We know a lot about cats. We know that they’re adorable, they make us happy and they can survive a fall from a 32-story building. But apparently, there’s still a lot we don’t know about them. Here are four things we only recently discovered about cats.

1. Sharp, tiny “papillae” on cat tongues help deep-clean their fur.

Cats spend much of their time licking themselves. On the surface of their tongue are hundreds of tiny claw-shaped spines called papillae, each the size of half a grain of rice. Recently, a study published in PNAS revealed the purpose of these structures. The authors found that the tips of the papillae create a U-shaped cavity (imagine a coffee straw cut in half). The cavity holds saliva and helps move it down through the fur to the cat’s skin, allowing deeper cleaning. “Why should I care,” you ask? With these results, the authors created a brush that mimics a cat’s tongue. It tugged less and was easier to clean than a normal brush. The new design could be used to distribute cleaning solutions into carpets. Or, remove allergens from cat fur.

2. Feral cats aren’t great at controlling city rat population.

Many people assume that feral cats hunt and kill rats, helping control city rat population. However, a recent study showed that they’re not doing a great job. The researchers set up cameras around a rat colony in New York City and recorded the behaviors of feral cats that came near. A lucky graduate student watched all 306 videos and tallied cat behaviors such as walking, stalking and chasing. Over 79 days, only three times did a cat actively hunt a rat; and of the two cases in which the hunt was a success, the rats were relatively small in size. The presence of the cats did, however, cause the rats to hide more. Bottom line, let’s not release cats to control rat population.

3. Male cats tend to be left-pawed, and females right-pawed.

Just like humans can be left- or right-handed, cats also prefer using one of their paws over the other. The scientific term for this is called laterality, and it has been examined in many animals including rats, frogs, primates and whales. In this recent study, the paw preference of 44 pet cats were examined in their own homes. They found that most cats showed laterality when reaching for food (73%), stepping down stairs (70%) or stepping over their litter box (66%). While 90% of humans are right-handed, laterality in cats is much more equal—roughly half are left-biased and half right-biased. Surprisingly, the researchers also discovered that male cats are much more likely to prefer their left paw, while females prefer their right paw. The reason is unclear, but it may hint at the underlying differences of the male and female brains.

4. Cats domesticated themselves over thousands of years without much genetic change.

Humans can’t tell cats what to do—they do what they want, when they want. If you’ve ever had a cat, you know it’s true. In fact, this statement also applies to how they were domesticated. In a comprehensive study, researchers examined ancient DNA from more than 200 cats spanning the last 9,000 years and found that the modern domestic cat comes from two main lineages: one from southeast Asian and the other from Egypt. Cats likely began hanging out with humans when our ancestors began farming. With an abundance of rodents that fed on crops, cats voluntarily stayed close and slowly domesticated on their own. The genetic makeup of domesticated cats hasn’t changed much over thousands of years, except the appearance of striped or blotched tabby coat markings. And why would they change? They’re perfect just the way they are.

5 of Our Favorite Blogs from 2018

We have published 130 blogs here at Promega this year (not including this one). I diligently reviewed every single one and compiled a list of the best 8.5%, then asked my coworkers to vote on the top 5 out of that subset. Here are their picks:

1. The Amazing, Indestructible—and Cuddly—Tardigrade

No surprises here, everyone loves water bears. Kelly Grooms knows what the people want.

The face of a creature that is nigh un-killable.

Continue reading “5 of Our Favorite Blogs from 2018”

RAIN Incubator Turns Students into Scientists

Judy Nguyen wasn’t looking for an adventure as the Head of Scientific Research at a fledgling incubator for students. She just finished her Ph.D. in molecular biology and neuroscience, and was looking for stable work in scientific research or biotechnology. However, when she arrived in Tacoma, Washington, she was disappointed by the opportunities available to her.

“With Puget Sound, in the Pacific Northwest, so outdoorsy…Most of Tacoma is environmental science, which is not my background,” Judy says. “I had a hard time finding anywhere to fit in.”

Judy finally found a position with an engineering company, but she didn’t feel quite at home. One day, her boss sent her out for an external meeting with a professor who had, she was told, “cool ideas.” She was instructed to establish a connection and return with ideas for how her company could collaborate with the “crazy professor.” As it turns out, that “crazy professor” had an idea for an organization to spark a revolution in the life science community around Tacoma.

Continue reading “RAIN Incubator Turns Students into Scientists”

A Healthier Kind of Blues

We are in the midst of a very intense time of the year, with holidays and seasonal celebrations like Thanksgiving (recently past), Hanukkah this week and Christmas a mere two-plus weeks away.

Wrap that up with a New Year’s celebration and “Wham”—more friends, family and food/alcohol than one normally enjoys in a three-month period.

Yet it can also be the season of SAD—seasonal affective disorder, when the amount of daylight decreases daily, and for those of us in the northern latitudes, cold weather intensifies. We’re eating more, getting less sunshine and quite probably less exercise. Hibernation is great for bears, not so good for humans.

It’s the wintertime blues. For myself and many, once the solstice passes and day length starts to increase, mood improves. But noticeable day-length increases don’t really occur here until mid-February. That’s a long time to feel blue. Continue reading “A Healthier Kind of Blues”

Learning New Things About mtDNA Inheritance from a Four-Year-Old Boy and a Tenacious Team of Scientists

We inherit our cells’ mitochondria from our mother. These energy-producing organelles are present in large numbers in most cells, meaning that cells can contain thousands of copies of the DNA associated with the mitochondria (mtDNA)—all passed on wholly from our mother. New evidence suggests, however, that this cannon principle of maternal-only inheritance of mtDNA might need to be refined. And it all started with a four-year-old boy.

Continue reading “Learning New Things About mtDNA Inheritance from a Four-Year-Old Boy and a Tenacious Team of Scientists”

Fun with Science for the Holidays: An “Actor’s” Perspective

This past weekend, I had the opportunity to be a part of “Once Upon a Christmas Cheery in the Lab of Shakhashiri”. Bassam Z. Shakhashiri is a professor of chemistry at the University of Wisconsin–Madison who is well-known for his fun science demonstrations and a fervent dedication to public science communication. Once Upon a Christmas Cheery started in 1970 as an end-of-semester treat for Dr. Shakhashiri’s freshman chemistry class; by 1973, the Christmas lecture had become so popular that Wisconsin Public Television offered to broadcast it during Christmas week, and this collaboration has continued uninterrupted ever since.

That’s 49 years of Christmas lectures, commemorated by making indium, the 49th element, the Sesame Street-esque “sponsor” of the show. It helps that indium burns bright violet, the name of Dr. Shakhashiri’s granddaughter and hence his favorite color. The color purple made a firm foundation for many aspects of the show: The chrysanthemums frozen in liquid nitrogen were purple, as was the balloon I inflated during my spiel on air movement. Most of the set was various shades of purple, too.

Bassam Shakhashiri and J. Nepper on the set of Once Upon a Christmas Cheery
The set was whimsical and very purple. Photo by Eric Baillies.

Continue reading “Fun with Science for the Holidays: An “Actor’s” Perspective”

How To Make Medicine on Mars

Today NASA’s InSight lander will touch down on Mars. InSight, which launched on May 5, is NASA’s first Mars landing since the Curiosity rover in 2012. The lander will begin a two-year mission to study Mars’ deep interior, gathering data that will help scientists understand the formation of rocky planets, including Earth.

NASA's InSight lander approaching Mars.
Image credit: NASA/JPL-Caltech

While every spacecraft that reaches Mars offers more knowledge of the Red Planet, a lot of the excitement is fueled by hopes that someday these missions will bring humans to Mars and enable us to start colonies there. While this goal seems very distant, tremendous progress is being made. Scientists around the globe are making incremental discoveries that will lead to the advances necessary to make colonization of Mars a reality.

I had the pleasure of meeting one team of scientists doing just this—eight high school students from iGEM Team Navarra BG. I met the team and their advisors at the 2018 iGEM Giant Jamboree, where they presented their synthetic biology project, BioGalaxy, as part of the iGEM competition. The problem they aimed to solve is key to helping humans stay on Mars for an extended period of time—how do you take everything you need when there isn’t enough room on the spacecraft? Continue reading “How To Make Medicine on Mars”

Dear Tech Serv, Thank You!

It’s that time of year again. Time to be thankful and show gratitude for those special people in your life. The undergrad who does the dishes, the labmate who shares their buffers when yours runs out, the collaborator that sends you data on a Saturday… Take a moment this week to say thank you, or send them an email to show your appreciation.

Today, we want to thank our Technical Services team. They work hard to help researchers choose the right assay for their needs, understand results and troubleshoot technical problems. They strive to provide the best service for those in need. Many on the receiving end have sent thankful messages:

“I deeply appreciate the help you have been and the email you just sent. I think with the information here, I may have sorted out an issue that has plagued our lab for the past few months.”

“Cannot tell you how grateful I am–you’ve been a tremendous help.”

“You are super sharp and caught critical errors in my protocol (the calculation and dilution errors you referenced below). While few of my colleagues run kinase assays, I did consult 6 of them, and none caught the errors you did. You’re clearly an expert and I truly appreciate how you’ve tailored everything for my ‘beginner’ level.”

“Wow, I cannot thank you enough! You have NO idea how helpful this is! You guys are absolutely great.”

Here’s one heart-warming story we had to share in which Tech Serv helped a group of students turn frowns into smiles.

In April, Tech Serv received a message from a professor from a university in Michigan regarding an issue with the pGEM Vector System. He was teaching a cell and molecular biology course and his students were unable to generate any colonies. “I have a very disappointed group of seniors on my hands. Please see the photo attached. All those sad faces trying to exude how hard they’ve worked with nothing to show for it. Any insight would be greatly appreciated,” he wrote.

“I understand the frustation of a kit that is not working, the students look so sad!” replied the Tech Serv team. Turns out, the cells may have been past expiration or subjected to repeated freeze thaws that caused the cells to lose competence. Tech Serv sent them a replacement kit with a photo of the team for encouragement.

“We greatly appreciate you replacing what we have and aim to turn those frowns into happy faces before graduation,” the professor replied.

Two weeks later, they got their colonies and wrote back: “It worked very well! We were able to make the most of this and they experienced a very good exercise in troubleshooting. I would say the group would view all that happened as a success. Thank you, we will continue to order from Promega as you’ve always proven to be a very client-friendly company!”

Nothing brings more happiness to the Tech Serv team than your success, so don’t hesitate to contact them with any questions you may have. They’re here to help.

Thanks, Tech Serv!

The Five Steps to miRNA Profiling

MicroRNAs (miRNAs) are small, non-coding RNAs that play a role in regulating cancer by acting as both tumor suppressors and oncogenes. Ranging in size from 18–25 nucleotides, miRNAs function in feedback mechanisms to regulate many cellular processes including cell proliferation, apoptosis, cell signaling and tumorigenesis (1).

Not surprisingly, dysregulation of miRNA expression can have serious repercussions. For example, miRNAs are dysregulated in almost all human cancers (1). Because of the potential to influence cancer growth and development, there is growing interest in miRNA profiling to identify possible biomarkers for cancer diagnosis or prognosis, as well as potential therapeutic targets (1).

Growing interest in miRNAs as both biomarkers of disease and therapeutic targets drives the need for fast and effective methods for miRNA profiling. Profiling miRNA targets follows a relatively simple workflow: sample selection, RNA extraction, RNA QC and quantitation, RNA profiling and data analysis (2,3). So what happens at each step?

Five steps of miRNA profiling
The Five Steps of miRNA Profiling

Continue reading “The Five Steps to miRNA Profiling”