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.◼
Over at the collaborative science blog Nothing in Biology Makes Sense!, guest contributor Levi Morran examines the processes by which bacteria can lose genes over generations of evolution.
In a recent paper, Lee and Marx (2012) test both how and why they observe large-scale patterns of gene loss in their experimentally evolved populations of Methylobacterium extorquens. They evolved these bacterial populations under different treatments of resource availability (realms of specialization) and found that all replicate populations adapted to their specific treatment over 1,500 generations. During experimental evolution, 80% of the bacterial populations exhibited nearly a 10% reduction in genome size, and many of the gene losses occurred in similar regions of the genome, some even across treatments.
To learn how and why those genes disappeared, go read the whole thing.◼