How the tiny parasite Toxoplasma alters its host’s behavior

Scanning electron micrograph of a Toxoplasma gondii tissue cyst in the brain of an infected mouse. Credit: David Ferguson /

Scanning electron micrograph of a Toxoplasma gondii tissue cyst in the brain of an infected mouse. Credit: David Ferguson /

It’s been a while since I received my PhD, but I finally got around to writing an article about the parasite I spent so many years studying in graduate school. That would be Toxoplasma gondii, a tiny intracellular parasite that infects just about any warm-blooded animal, including humans.

My PhD thesis focused on how Toxo invades human cells and makes itself at home, but this parasite is probably more famous for its ability to make rats and mice lose their instinctive fear of cats. That’s a pretty handy trick, as that could in theory make Toxo-infected rodents easy prey for cats. And cats are the only host where Toxo reproduces sexually, so getting into felines allows the parasite to complete its life cycle.

How exactly does a tiny intracellular parasite influence its host’s behavior? Figuring that out has been a challenge. Every time researchers think they have the answer, Toxo seems to confound their expectations.

What makes this particularly interesting is that Toxo is estimated to infect about a third of all humans, and has been associated with various disorders in humans as well, from schizophrenia and suicide attempts to traffic accidents and cultural differences. To be fair, a lot of the human data isn’t particularly robust or convincing…part of my motivation to finally write about Toxo is the fact that there are a lot of misleading or overly speculative articles about what Toxo does in humans, and the evidence for a lot of those effects is pretty weak.

Still, in theory if we understand what Toxo does in rodents, that might help us figure out how it affects us.

We may finally be getting closer to understanding how exactly Toxo manipulates mammalian behavior, and there are some pretty compelling new theories. You can check out my new feature in Ars Technica for more details.

There were definitely pros and cons to writing about a parasite I know so well, and spent so much time thinking about and working on for so many years. On the one hand, I was excited to finally write about Toxo, and I knew a lot about the parasite before I even started my reporting. On the other hand, I maybe knew too many details… I had to work pretty hard to keep the article interesting for a general audience, rather than delving into minutiae that only Toxo researchers would care about.

I also initially included a lot more details about the research in humans, but as I mentioned, that research is pretty messy and inconclusive, and doesn’t really relate very well to the research in rodents, so I decided it was better left to a future article.

Anyway, check out the feature here for a deep dive into how Toxo manipulates rodent behavior.

How the gut “tastes” parasites, blood vessels “see,” and kidneys “smell” fatty acids and regulate blood pressure in response

Tuft Cells in the gut "taste" parasites

Tuft Cells in the gut “taste” parasites

In my latest feature for The Scientist Magazine, I wrote about how sensory receptors — the light, taste, and odor receptors that are primarily present in our eyes, tongues, and nose — are present all over the body, and have all kinds of functions. 

It turns out taste receptors in the gut and airway influence some of the earliest immune responses to bacteria and parasites, and your ability to taste bitter substances could influence how prone you are to respiratory infections. 

Also, blood vessels relax in response to light, and odor receptors in the kidney regulate blood pressure in response to fatty acids produced by gut bacteria, providing a means by which diet could directly affect blood pressure. Other odor receptors could affect how prone muscles are to injuries, how quickly skin wounds heal, and how sperm find their way to the egg.

Check out the full article here, and here are some illustrations for it.

An online feature about deep life for Smithsonian

Nematodes (blue) wiggle inside a stalactite from a South African gold mine in this image taken with an electron microscope. (Credit: Gaetan Borgonie)

Nematodes (blue) wiggle inside a stalactite from a South African gold mine in this image taken with an electron microscope. (Credit: Gaetan Borgonie)

I just got done with a Smithsonian feature on microbes that live in extremely inhospitable environments deep beneath the Earth’s surface, and the researchers who venture 2 kms or more underground in South African gold mines to study them.

It’s hard work, but they’ve found a surprising diversity of life living in these deep environments, and it turns out studying these microbes can give us clues about life on other planets. Check out the story here.

Really enjoyed reporting and writing this one, especially since it’s about microbiology, something that I spent so many years studying both as an undergrad and during my PhD…

How scientists can get credit for peer review: Science Careers article

Thanks to all the time I spent getting my PhD, I’ve maintained an interest in writing about careers in science, especially articles that might be helpful for graduate students and postdocs.

I wrote this article for Science Careers about different platforms (such as Publons, Elsevier’s Reviewer Recognition Platform) that allow scientists to get credit for peer review. It was very interesting to learn about these services, and I hope the article is helpful for early career researchers. You can check it out here.

Keeping busy, writing about molecular biology for BioTechniques

Developing Drosophila Embryo (Credit: Credit: Raghav Chhetri, Fernando Amat, Yinan Wan, Burkhard Höckendorf, William Lemon & Philipp Keller, Janelia Research Campus.)

Developing Drosophila Embryo (Credit: Credit: Raghav Chhetri, Fernando Amat, Yinan Wan, Burkhard Höckendorf, William Lemon & Philipp Keller, Janelia Research Campus.)

I’ve been meaning to update this website for a while, unfortunately I’ve been too busy writing articles to do so.

Among other things, I’ve been writing regular articles for the journal BioTechniques. It’s been a nice way for me to keep in touch with the latest in molecular biology, a field that I haven’t extensively written about for a few years.

I’ve written a bunch of articles for them so far, including short articles on a new way to study membrane receptors and a drug that helps worms stay young longer.

I also wrote some longer articles on the hottest topic in molecular biology right now, CRISPR-Cas9, as well as advances in how researchers photograph developing embryos and in synthetic biology, where researchers engineer cells to perform basic computational tasks.

I have several more articles on a wide variety of topics coming up. It’s just amazing to see the rate at which research techniques in the life sciences are advancing!

You can check out any future BioTechniques articles here

When it rains, it pours: my article about the monsoons and floods in India

Indian floods

Indian floods

This article on flooding in India and Pakistan has been a long time coming. I did the bulk of the reporting last year right after the devastating September 2014 floods in Kashmir, only for the article to get delayed until now.

Floods occur every year in South Asia, causing widespread damage and loss of life. Unfortunately it turns out that floods in both India and Pakistan are likely to get more frequent and more devastating, due to a combination of climate change and poorly-planned development. More will have to be done on both fronts to try to prevent flood disasters in the future. Check out my article for more details.

This was an interesting one to write and report, on what I think is an important topic, I hope to do more such stories. Obviously the long delay necessitated some revisions and compromises, and also resulted in a broader focus, mostly I’m just happy to see the article published at last.

This Software Makes You Forget You’re Wearing Headphones — My article about 3D audio

View story at

I got a chance to write another longer piece, this one about 3D audio and how it can make headphones sound more like real life, particularly important for virtual reality and augmented reality. It’s been a while since I last wrote a tech-focused article, and this was also my first piece for Medium’s Backchannel publication.

It was a fun one to report–I got to visit a local startup called VisiSonics based out of the University of Maryland and try out their 3D audio tech demos. This included my first experience of the new Oculus virtual reality headsets, which was exciting.

The last time I tried any VR was back in the early 90s, when I played some Virtuality arcade games (What I like to call the “Lawnmower Man” era of VR…). Needless to say, VR has definitely come a long way since then.

One of the nice parts of writing this piece was getting to know DC’s virtual reality startup scene. There are a lot of interesting startups and developers working on some exciting ideas (of course, there are far more in Silicon Valley and other large tech hubs). It’s one of the reasons I think it’s an exciting time for VR, there’s so much innovation happening around both hardware and software and so many smart people excited about it that I figure it will make some sort of an impact, even if no one’s quite sure what the consumer market will actually look like. But with the first consumer VR headsets expected within the next year, I guess we’ll find out soon.

A foggy feature

Coastal fog along California's Pacific Coast Highway. Credit: Sandeep Ravindran

Coastal fog along California’s Pacific Coast Highway. Credit: Sandeep Ravindran

Here’s a longer feature article that I wrote for The Verge, a science and technology site that I read fairly regularly.

The article is about researchers who are developing more efficient methods to harvest water from fog. In particular I focused on a new fog collector based on the beaks of shorebirds, but I also provided a broad overview of existing techniques to collect fog water, where they can be useful, and whether such techniques could help supplement our water supply. Check it out here, I like how it’s laid out with nice images and videos.