Continued findings on bacterial growth, resistance


Scientists at The Scripps Research Institute (TSRI) have unraveled a complex chemical pathway that enables bacteria to form clusters known as “biofilms.” Biofilm formation occurs when bacterial cells adhere to each other and to surfaces as part of their growth cycle or to set up a defense against attack: Cells on the outside of a biofilm are susceptible to antibiotics but protected interior cells are more difficult to kill.

Biofilms play key roles in conditions ranging from gum disease to cholera, and from cystic fibrosis to Legionnaires’ disease. When biofilms form on medical devices, such as heart valves or catheters, deadly infections can follow.

The TSRI findings build on past research on the role of nitric oxide in initiating a chemical cascade that leads to a number of physiological functions in the body. In sufficient quantity nitric oxide is toxic to bacteria, so it was logical that nitric oxide would trigger bacteria to huddle into a biofilm. But nobody knew precisely how. In this study, TSRI researchers detailed the signaling pathway from nitric oxide through cellular regulators and on to biofilm formation.

The study appears in the journal Molecular Cell. News release at

Gene duplication helped our brains become ‘human’

A team led by scientists at The Scripps Research Institute (TSRI) has shown that an extra copy of a brain-development gene, which appeared in our ancestors’ genomes about 2.4 million years ago, allowed maturing neurons to migrate farther and develop more connections.

Surprisingly, the added copy doesn’t augment the function of the original gene, which makes neurons sprout connections to neighboring cells. Instead it interferes with that original function, effectively giving neurons more time to wire themselves into a bigger brain.

The study of human-specific gene duplications could lead to a better understanding of human developmental disorders and also suggests a new way to think about how evolution occurs.

The findings appear in the journal Cell. News release at

Overweight teens satisfied with body shape less prone to depression

A study of the relationships between body satisfaction and healthy psychological functioning in overweight adolescents has found that young women who are happy with the size and shape of their bodies report higher levels of self-esteem. This positive outlook suggests that improving body satisfaction could be a key component of interventions for overweight youth.

The findings suggest the girls in the study may also be protected against the negative behavioral and psychological factors sometimes associated with being overweight such as fasting, skipping meals, or induced vomiting.

The study, conducted by the UC San Diego School of Medicine, appears in the Journal of Adolescent Health. More information at

— Lynne Friedmann is a science writer based in Solana Beach.