Posts byAlex Padron

Digesting The Past

A few weeks ago, I was having coffee with a friend from the Hopkins molecular biology program; he left me somewhat dumbfounded with the story he told me. It involved a walking, talking experiment and an obsessed scientist (which one isn’t?) who revolutionized the concept of what makes humans…well, human; that is, it shifted the idea that the stomach contained the contents of humanity to the brain. This story is also inspired by my recent completion of a neuroscience boot camp at UC Berkeley. So without further adieu, here is the serendipitous and lucky story of Alexis St. Martin: the man with a hole in his stomach and his surgeon, William Beaumont.

On June 6, 1822 in Mackinac Island, Michigan, a French-Canadian fur trader, Alexis St Martin, was shot in the stomach when a shotgun was accidentally discharged (Fig 1). Luckily for Alexis, the fort’s doctor, William Beaumont, was nearby and quickly began to treat him. As if the damaging impact of a shotgun blast wasn’t enough, Beaumont’s treatment was unsterile and anesthetic-free. Mind you, this all happened before Louis Pasteur came up with his famous germ theory of disease. At the time it was generally accepted that God and miasmas caused plague and disease: people would resort to praying and burning tar to ‘cleanse the air’ of disease. I’m therefore sure Alexis relived the pain of his shotgun blast several times during his surgeries with Dr. Beaumont.

Fig 1. An artistic rendering of Alexis St Martin's fistula made by a gunshot wound.

Alexis had several wounds from the blast, but the most significant of all was a gaping hole that never fully sealed, which formed a fistula. Nonetheless, he lived, remarkably. And since Alexis was unable to work due to his circumstances, Beaumont hired him as a handyman. This gave Beaumont a fantastic opportunity, one he exploited to a great degree, once he realized what he had in front of him during one of their wound cleaning sessions. That is, a peek (literally) into human digestion: a process people had known little to nothing about prior to Beaumont’s reportings. Before long, Beaumont began performing experiments on Alexis (Fig 2). These involved dipping food into the fistula and measuring the amount of time it took to digest. Vegetables and chunks of meat were tied to a string and inserted into Alexis’ stomach. Beaumont made him fast for hours on end, then removed gastric juice from his stomach and watched it digest foods in vials. Things like corned beef took almost 5 times as long outside the stomach than inside to digest—neat, huh?

Bdelloid Rotifers: Sex,Take 2

Isaac Newton, one of the most famous physicists to have ever existed, lived to be 84 years old and did so under a celibate promise. Imagine a lifetime without sex. Now imagine tens of millions of years without sex: meet the Bdelloid rotifers (Fig 1). These tiny, female-only metazoans (0.5 mm in length) are well-known for their asexuality and resilience toward desiccation and ionizing radiation. And while other animals like komodo dragons, stick-insects (Timema stick-insects have reproduced asexually for over 1 million generations!), and some sharks can asexually reproduce in response to the lack of viable males (in most cases), it’s incredibly rare to see an animal that reproduces asexually exclusively. Bdelloid (pronounced del●loi●d) rotifers are an “evolutionary scandal“, completely challenging the sexual reproduction dogma—that is, introducing genetic variation to allow species to adapt to their dynamic environments in addition to mitigating genetic degradation for the benefit of the population.

Not having sex isn’t what necessarily makes rotifers scandalous (bacteria don’t have sex and look at how well they’re doing), it’s that they’re complex multicellular organisms who have speciated to a degree similar to that of sexually reproducing organisms and who have done so asexually.

The Poetry of Science: stick a fork in it.

star-clusters-74052_640It’s difficult not to be inspired by monumental scientific accomplishments. It speaks to the progress of the human species. Whether it’s the sequencing of the human genome or the realization that the fundamental components of the human body were manufactured in the core of stars throughout our galaxy, these seminal works give us a larger glimpse of the real world around us.

The human gene-what? My atoms were made where?

Okay, maybe you’re familiar with the sequencing of the human genome but you may be less familiar knowing that the same atomic particles fabricated in stars scattered throughout the depths of the cosmos constitutes your very existence. How about the reprogramming of differentiated cells? ENCODE? Probably not. This to me isn’t surprising considering these important tour de force works included an array of authors, taking away from the poetic nature of the lone scientist “burning the midnight oil”.

Quorum sensing, microbes, and squids

Bobtail SquidAll microbes communicate with members of their own species and between species. This type of communication, called quorum sensing, allows bacteria to form rich social networks with their neighbors. Bacteria use quorum sensing to keep tabs on the density of members of their species in relation to the density of other species in order to perform fantastically synchronous events that they could never accomplish working in isolation–like the successful invasion of a host. And while pathogen-host interactions are incredibly intricate, beautifully structured, and close to my heart (figuratively) I’ll be focusing on a wonderfully evolved symbiotic relationship between a microbe and a squid: Vibrio fischeri and its life partner, the Hawaiian bobtail squid.