SPLASH! milk science update: MAY 2013 Issue

This month’s newsletter tells the story of DNA-protein nets found in cow’s milk that trap and kill bacteria, the immense task of cataloging all bacterial species found in milk, how milk letdown evolved and the hormones responsible for this critical physiological response, and a review of Mary Roach’s new book.

We hope you enjoy this action-packed issue of SPLASH! milk science update!

Milk Cells Cast NETs to Snare Pathogens

Milk Cells Cast NETs to Snare Pathogens

The list of proteins in cow’s milk just keeps getting longer. Tim Reinhardt and colleagues have now discovered nearly 3000 unique proteins in cow’s milk (1). While that would be a story by itself, they also reveal evidence for web-like nets that immune cells secrete into milk when pathogens are present. Yes, milk is cooler than fiction. Read More...

Bacterial Count

Bacterial Count

A new study scans breast milk for the different bacterial species found in it. Species that can grow whether or not there is air around them colonize a baby’s intestine first, but are then overrun by other species that flourish in the absence of oxygen, like Bifidobacterium infantis. The class Clostridia can be found in breast milk, and probably travels there from mom’s gut.   Milk enthusiasts probably all share a favorite bacterium: Bifidobacterium infantis, the species that coevolved with humans and promotes a healthy infant gut. Breast milk contains many other kinds of bacteria, but recording the full species register is a surprisingly tricky task. Recently, a team of Swiss researchers did the most complete job yet.   Ted Jost and others1 in the Zurich-based group took milk samples from seven women at three intervals after giving birth, cultured the milk in various ways, and then sequenced the DNA in the milk using multiple techniques. That should cover all the bases. Their culture methods, numbering nine, catered for bacteria of every lifestyle choice. They laced agar jelly with all manner of nutrient mixtures and provided airy compartments for species that like to grow in oxygen. Meanwhile species that flourish despite an absence of oxygen (facultative anaerobes) or can’t handle life in its presence (obligate anaerobes) were given the chance to grow in an anaerobic chamber. Usually, the first kinds of bacteria to set up camp in a baby’s intestine are facultative anaerobes like Escherichia coli species. As expected, Streptococci, another facultative anaerobe, was one of the most common categories identified in Jost et al.’s study. Then, after a few days, when the facultative anaerobes have used up the oxygen in a baby’s gut lumen, populations of obligate anaerobes, like Bifido species, start to take off2. And Bifidobacterium infantis, by far […] Read More...

The Evolutionary Origins of Milk Letdown

The Evolutionary Origins of Milk Letdown

The production of milk by the mammary gland is a key adaptation of mammals. But simply producing the milk is not enough; that milk needs to get from the mammary gland to the nipple to be ingested by the infant. But how is this movement of milk accomplished? An amazing hormone called oxytocin. How did oxytocin, and therefore milk letdown, it evolve? Read More...

A Delectable Gobble

A Delectable Gobble

The last time I read Mary Roach was on holiday, in the evenings that followed long hikes up, along, and down tabletop mountains in southern Venezuela. I read aloud from Stiff: The Curious Lives of Human Cadavers because my tent buddy was too careful a packer to have allowed himself the additional mass of a book. As he sensibly tended to sore blisters and swollen bites, I enriched the moment by, for example, loudly vocalizing Roach’s prose about the precise details of how and when death occurs in people who are unlucky enough find themselves inside planes that explode in the sky. This time I’m digesting Gulp: Adventures on the Alimentary Canal in the tearoom of the University Library in Cambridge, England. Read More...