Nothing in Biology Makes Sense: Making sense of maternal mammary metagenomics

Breastfeeding symbol Breastfeeding. Image via Topinambour.

This week at Nothing in Biology Makes Sense!, Sarah Hird digs into a new study of the bacterial diversity in human breast milk.

Cabrera-Rubio et al. (2012) analyzed the bacterial composition of HBM [human breast milk] from 18 women at three time points over 6 months. The mothers in the study varied in weight and delivery method. The researchers were basically exploring what factors influence the microbial composition in breast milk, with an emphasis on weight of the mother. They used next-generation sequencing to produce a library of sequences that were analyzed for what specific bacteria were found in each sample and how the samples relate to one another as whole communities.

Some of the factors that turned out to influence bacterial diversity in HBM are pretty surprising — to find out what they are, go read the whole thing.◼

Nothing in Biology Makes Sense: Making sense of “stinkbird” gut microbes

A hoatzin. Photo by Carine06.

I was off the grid last week, so I missed Sarah Hird’s latest post at the group blog Nothing in Biology Makes Sense!, discussing a cool new study of the microbes in the guts of hoatzins, a species of wonderfully weird birds.

The hoatzin has an enlarged crop for the purpose of fermentation (see figure below). A “crop” is an anatomical structure in throat of some animals (including most birds) that primarily stores food. In the hoatzin, however, it does much, much more. Foregut fermentation is a digestive strategy where microbes living in or before the stomach break down vegetation for their host. Microbes are required by foregut fermenters because only the microbes are capable of breaking down the cell wall of plants, a barrier that confines most of the nutrients found in plant cells. The hoatzin is the only bird to use foregut fermentation and is the smallest known foregut fermenter.

To learn what the new study reveals about the diversity of microbes in hoatzin foreguts, go read the whole thing, including the evolving plans for follow-up experiments in the comments. ◼