thereby hangs a tale

Solar system has a tail, just like comets: US space agency

AP | Jul 11, 2013, 03.18 AM IST

Scientists revealed images showing the tail emanating from the bullet-shaped region of space under the grip of the sun, including the solar system and beyond.

CAPE CANAVERAL (Florida): Our solar system has a tail, just like comets. Now the US space agency can prove it.

Scientists revealed images on Wednesday showing the tail emanating from the bullet-shaped region of space under the grip of the sun, including the solar system and beyond. The region is known as the heliosphere, and the tail is called the heliotail.

The findings are based on data from Nasa's Interstellar Boundary Explorer, or IBEX.

Scientists always presumed the heliosphere had a tail, but this provides the first real data on its shape.

Chief IBEX investigator David McComas says it's difficult to calculate the length of the heliotail. But the evaporating end of the tail could stretch 100 billion miles.

pilocytic astrocytomas found defects in genes

BERLIN: Scientists have found that an overactive signalling pathway is a common cause in cases of pilocytic astrocytoma, the most frequent type of brain cancer in children.

Scientists coordinated by the German Cancer Research Center (as part of the International Cancer Genome Consortium, ICGC) in 96 gemone analyses of pilocytic astrocytomas found defects in genes involved in a particular pathway.

They believe that drugs can be used to help affected children by blocking components of the signalling cascade.

Pilocytic astrocytomas are the most common childhood brain tumours. These tumours usually grow very slowly. However, they are often difficult to access by surgery and cannot be completely removed, which means that they can recur.

In previous work, researchers led by Professor Dr Stefan Pfister and Dr David Jones had already discovered characteristic mutations in a major proportion of pilocytic astrocytomas.

All of the changes involved a key cellular signalling pathway known as the MAPK signalling cascade. MAPK is an abbreviation for 'mitogen-activated protein kinase'.

This signalling pathway comprises a cascade of phosphate group additions (phosphorylation) from one protein to the next - a universal method used by cells to transfer messages to the nucleus.

MAPK signalling regulates numerous basic biological processes such as embryonic development and differentiation and the growth and death of cells.

"A couple of years ago, we had already hypothesised that pilocytic astrocytomas generally arise from a defective activation of MAPK signalling," said Jones, first author of the study in journal Nature Genetics.

"However, in about one fifth of the cases we had not initially discovered these mutations. In a whole-genome analysis of 96 tumours we have now discovered activating defects in three other genes involved in the MAPK signalling pathway that have not previously been described in astrocytoma," he said.

"Aside from MAPK mutations, we do not find any other frequent mutations that could promote cancer growth in the tumours. This is a very clear indication that overactive MAPK signals are necessary for a pilocytic astrocytoma to develop," said study director Pfister.

"The most important conclusion from our results is that targeted agents for all pilocytic astrocytomas are potentially available to block an overactive MAPK signalling cascade at various points," said Pfister.

"We might thus in the future be able to also help children whose tumours are difficult to access by surgery," he said.

Brain's 'switch' for long-term memory identified

PTI | Jul 9, 2013, 01.45 PM IST

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BERLIN: Scientists have identified calcium in the cell nucleus to be a cellular "switch" responsible for the formation of long-term memory.

Neurobiologists at Heidelberg University in Germany used the fruit fly Drosophila melanogaster as a model to investigate how the brain learns.

The team led by Professor Dr Christoph Schuster and Professor Dr Hilmar Bading wanted to know which signals in the brain were responsible for building long-term memory and for forming the special proteins involved.

The team from the Interdisciplinary Center for Neurosciences (IZN) measured nuclear calcium levels with a fluorescent protein in the association and learning centres of the insect's brain to investigate any changes that might occur during the learning process.

Their work on the fruit fly revealed brief surges in calcium levels in the cell nuclei of certain neurons during learning. It was this calcium signal that researchers identified as the trigger of a genetic programme that controls the production of "memory proteins."

If this nuclear calcium switch is blocked, the flies are unable to form long-term memory.

Schuster explained that insects and mammals separated evolutionary paths approximately 600 million years ago. In spite of this sizable gap, certain vitally important processes such as memory formation use similar cellular mechanisms in humans, mice and flies, as the researchers' experiments were able to prove.

"These commonalities indicate that the formation of long-term memory is an ancient phenomenon already present in the shared ancestors of insects and vertebrates. Both species probably use similar cellular mechanisms for forming long-term memory, including the nuclear calcium switch," Schuster said.

The researchers assume that similar switches based on nuclear calcium signals may have applications in other areas - presumably whenever organisms need to adapt to new conditions over the long term.

"Pain memory, for example, or certain protective and survival functions of neurons use this nuclear calcium switch, too," said Bading.

"This cellular switch may no longer work as well in the elderly, which Bading believes may explain the decline in memory typically observed in old age.

"Thus, the discoveries by the Heidelberg neurobiologists open up new perspectives for the treatment of age- and illness-related changes in brain functions," Bading said.

The study was published in the journal Science Signaling.