Ancient cities arose not by decree from a centralized political power, as was previously widely believed, but as the outgrowth of decisions made by smaller groups or individuals, according to a new study.

The research was led by Jason Ur, assistant professor of anthropology in the Faculty of Arts and Sciences at Harvard University, with Philip Karsgaard of the University of Edinburgh, and Joan Oates of the McDonald Institute for Archaeological Research of the University of Cambridge.

“The results of our work show that the existing models for the origins of ancient cities may in fact be flawed,” says Ur. “Urbanism does not appear to have originated with a single, powerful ruler or political entity. Instead, it was the organic outgrowth of many groups coming together.”

For bees, anyway. People are out of luck.

A research team led by the University of Illinois has identified an odorant receptor that allows male drones to find a queen in flight. The receptor, on the male antennae, can detect an available queen up to 60 meters away. This is the first time an odorant receptor has been linked to a specific pheromone in honey bees.

The “queen substance,” or “queen retinue pheromone,” was first identified decades ago, but scientists have only recently begun to understand its structure and role in the hive. The pheromone is a primary source of the queen’s authority. It is made up of eight components, one of which, 9-oxo-2-decenoic acid (9-ODA), attracts the drones during mating flights.

Only about a fifth of the genes in a cell are switched on at any given time but environmental changes such as smoking lead to changes in that genetic activity.

According to a Canadian team led by Wan L. Lam and Stephen Lam from the British Columbia Cancer Research Centre, smoking introduces some changes that are irreversible. Reversible changes were in xenobiotic functions( managing chemicals not produced in the body ), nucleotide metabolism and mucus secretion but some genes, such as GSK3B that are important in cell survival, are irreversibly damaged by smoking, and smoking also switched off genes that help combat lung cancer development.

The researchers took samples from the lungs of 24 current and former smoker, as well as from non-smokers who have never smoked.

Ivermectin, the standard drug for treating river blindness (onchocerciasis), is causing genetic changes in the parasite that causes the disease, according to a new study by Roger Prichard (McGill University, Canada) and colleagues, published on August 30, 2007 in the open-access journal PLoS Neglected Tropical Diseases. These genetic changes have previously been linked with parasites becoming resistant to ivermectin.

In studying how neurotransmitters travel between cells -- by analysis of events in the dimensions of nanometers -- Cornell researchers have discovered that an electrical current thought to be present during that process does not, in fact, exist.

These results were reported July 22 in the online edition of the journal Nature Cell Biology by Cornell researchers Liang-Wei Gong and Manfred Lindau, applied and engineering physics, as well as their colleague Guillermo Alvarez de Toledo at the University of Seville, Spain.

Researchers have made synthetic lipids called pseudoceramides that are involved in skin cell growth and could be used in treating skin diseases in which skin cells grow abnormally.

Ceramides are lipids found in the outermost skin layer called the stratum corneum, which is made of dead skin cells and mainly serves as a physical barrier. Ceramides' main biological function is to control how skin cells grow and differentiate - a process through which skin cells become specialized.