It used to be that being buried under a pile of large, sweaty men was the worst thing that could happen to you playing Rugby - but then it turned out a herpes virus can cause a skin disease called "scrumpox" and it spreads through physical contact.

Researchers have discovered that a new strain could be even more pathogenic - and it's now also found among sumo wrestlers in Japan.

"Scrumpox", or herpes gladiatorum, is a skin infection caused by the herpes virus, which can cause coldsores. It is spread through direct skin-to-skin contact so it is common among rugby players. Symptoms can start with a sore throat and swollen glands and the telltale blisters appear on the face, neck, arms or legs. The disease is highly infectious, so players who are infected are often taken out of competition to stop the virus from spreading.

A team of scientists has identified a gene in rice that controls the size and weight of rice grains. The gene may prove to be useful for breeding high-yield rice and, thus, may benefit the vast number of people who rely on this staple food for survival.

The researchers first searched for and identified mutant strains of rice that exhibited underweight grains. "We found a particular mutant that is defective in its ability to produce normal-sized grains," said Zuhua He, a biology professor at the Chinese Academy of Sciences and the leader of the team. The group then examined the mutant and found that it carried a mutation within the GIF1 gene. "The GIF1 gene is responsible for controlling the activity of the enzyme invertase, which is located in the cell wall and converts sucrose to substances that then are used to create starch," said He. "Invertase is important in the formation of starch within developing grains of rice. If invertase is not active, the rice plant cannot produce edible grains."

Instead of using a flat microchip as the light sensor for their new camera, a team of engineers has developed a sensor that is a flexible mesh of wire-connected pixels. The mesh is made from many of the same materials as a standard digital-camera sensor, but has the unique ability to conform to convoluted, irregular surfaces.

The technology breakthrough is a novel approach that bypasses a traditional planar sensor of adjacent pixels and instead relies upon an array of pixels interconnected by small wires. Using a flexible, temporary backing, the researchers can form the array into a curved shape and then transfer the array to its permanent location affixed to a glass lens.

Over the last 20 years, many researchers have tried to manufacture such electronic eye systems, but until now, none were able to create a working camera.

A protein required for the earliest steps in embryonic development also plays a key role in solidifying fear memories in the brains of adult animals, scientists have revealed. An apparent "hub" for changes in the connections between brain cells, beta-catenin could be a potential target for drugs to enhance or interfere with memory formation.

The protein beta-catenin acts like a Velcro strap, fastening cells' internal skeletons to proteins on their external membranes that connect them with other cells. In species ranging from flies to frogs to mice, it also can transmit early signals that separate an embryo into front and back or top and bottom.

University of Utah engineers have devised a new way to slice thin wafers of germanium for use in efficient solar power cells. They say the new method should lower the cost of such cells by reducing the waste and breakage of the brittle semiconductor.

Germanium solar cells are expensive and so are only now used mainly on spacecraft but with the improved wafer-slicing method, "the idea is to make germanium-based, high-efficiency solar cells for uses where cost now is a factor," particularly for solar power on Earth, says Eberhard "Ebbe" Bamberg, an assistant professor of mechanical engineering. "You want to do it on your roof."

Dinesh Rakwal, a doctoral student in mechanical engineering, adds: "We're coming up with a more efficient way of making germanium wafers for solar cells – to reduce the cost and weight of these solar cells and make them defect-free."

Natural grass fires are evidently more important for the ecology of savannahs than has previously been assumed, according to the findings of a study carried out in Etosha National Park in the north of Namibia.

Writing in the Journal of Ecology, researchers from the Helmholtz Centre for Environmental Research (UFZ), the University of Frankfurt am Main and the University of Cologne say that fire plays an important role in regeneration.

It is the first study to have investigated the complex interplay of the factors fire, competition, moisture and seed availability in relation to a grass species. Periodic fires in semi-arid regions can lead to older tufts of grass disappearing, thereby making room for younger grasses. The findings are particularly significant for the management of semi-arid nature reserves, in which, in the absence of natural plant eaters, fires are the only practical means of renewing the grass canopy.