Stability of the personal relationship networks in a longitudinal study of middle school students

The personal network of relationships is structured in circles of friendships, that go from the most intense relationships to the least intense ones. While this is a well established result, little is known about the stability of those circles and their evolution in time. To shed light on this issue, we study the temporal evolution of friendships among teenagers during two consecutive academic years by means of a survey administered on five occasions. We show that the first two circles, best friends and friends, can be clearly observed in the survey but also that being in one or the other leads to more or less stable relationships. We find that being in the same class is one of the key drivers of friendship evolution. We also observe an almost constant degree of reciprocity in the relationships, around 60%, a percentage influenced both by being in the same class and by gender homophily. Not only do our results confirm the mounting evidence supporting the circle structure of human social networks, but they also show that these structures persist in time despite the turnover of individual relationships-a fact that may prove particularly useful for understanding the social environment in middle schools.

Enhanced recombinant protein capture, purity and yield from crude bacterial cell extracts by N-Lauroylsarcosine-assisted affinity chromatography

BACKGROUND

Recombinant proteins cover a wide range of biomedical, biotechnological, and industrial needs. Although there are diverse available protocols for their purification from cell extracts or from culture media, many proteins of interest such as those containing cationic domains are difficult to purify, a fact that results in low yields of the final functional product. Unfortunately, this issue prevents the further development and industrial or clinical application of these otherwise interesting products.

RESULTS

Aiming at improving the purification of such difficult proteins, a novel procedure has been developed based on supplementing crude cell extracts with non-denaturing concentrations of the anionic detergent N-Lauroylsarcosine. The incorporation of this simple step in the downstream pipeline results in a substantial improvement of the protein capture by affinity chromatography, an increase of protein purity and an enhancement of the overall process yield, being the detergent not detectable in the final product.

CONCLUSION

By taking this approach, which represents a smart repurposing of N-Lauroylsarcosine applied to protein downstream, the biological activity of the protein is not affected. Being technologically simple, the N-Lauroylsarcosine-assisted protein purification might represent a critical improvement in recombinant protein production with wide applicability, thus smothering the incorporation of promising proteins into the protein market.