Supernova 2007ck (left) is a Type II event, and Supernova 2007co (right) is a Type Ia event.

In just the past six weeks, two supernovae have flared up in an obscure galaxy in the constellation Hercules. Never before have astronomers observed two of these powerful stellar explosions occurring in the same galaxy so close together in time.
The galaxy, known as MCG +05-43-16, is 380 million light-years from Earth. Until this year, astronomers had never sighted a supernova popping off in this stellar congregation. A supernova is an extremely energetic and life-ending explosion of a star.
Making the event even more unusual is the fact that the two supernovae belong to different types. Supernova 2007ck is a Type II event--which is triggered when the core of a massive star runs out of nuclear fuel and collapses gravitationally, producing a shock wave that blows the star to smithereens. Supernova 2007ck was first observed on May 19, Science Daily said.
In contrast, Supernova 2007co is a Type Ia event, which occurs when a white dwarf star accretes so much material from a binary companion star that it blows up like a giant thermonuclear bomb. It was discovered on June 4, 2007. A white dwarf is the exposed core of a star after it has ejected its atmosphere; it’s approximately the size of Earth but with the mass of our Sun.
“Most galaxies have a supernova every 25 to 100 years, so it’s remarkable to have a galaxy with two supernovae discovered just 16 days apart,“ says Stefan Immler of NASA’s Goddard Space Flight Center. In 2006 Immler used NASA’s Swift satellite to image two supernovae in the elliptical galaxy NGC 1316, but both of those explosions were Type Ia events, and they were discovered six months apart.
The simultaneous appearance of two supernovae in one galaxy is an extremely rare occurrence, but it’s merely a coincidence and does not imply anything unusual about MCG +05-43-16. Because the two supernovae are tens of thousands of light-years from each other, and because light travels at a finite speed, astronomers in the galaxy itself, or in a different galaxy, might record the two supernovae exploding thousands of years apart.

People with depression commonly process folate less efficiently.

A unique study by researchers at the University of York and Hull York Medical School has confirmed a link between depression and low levels of folate, a vitamin which comes from vegetables.
In research published in the July edition of the Journal of Epidemiology and Community Health, the York team led by Dr Simon Gilbody, concluded that there was a link between depression and low folate levels, following a review of 11 previous studies involving 15,315 participants, Science Daily reported.
Last month, the Food Standards Agency recommended to UK Health Ministers the introduction of mandatory fortification of either bread or flour with folic acid to prevent neural tube defects, which can result in miscarriage, neonatal death or lifelong disability. The York study suggests that the measure may also help in the fight against depression.
Dr Gilbody said: “Our study is unique in that for the first time all the relevant evidence in this controversial area has been brought together. Although the research does not prove that low folate causes depression, we can now be sure that the two are linked. Interestingly, there is also some trial evidence that suggests folic acid supplements can benefit people with depression. We recommend that large trials should be carried out to further test this suggestion.“
Recent research from the same team published in the American Journal of Epidemiology has also proved that people with depression commonly have a gene that means that they process folate less efficiently. Folate is linked to the production of some of the ’feel good’ chemicals in the brain, such as serotonin. The identification of this gene provides a plausible explanation as to why folic acid supplements may help people with depression.
Depression may soon become the second leading cause of disability worldwide. It affects between 5% and 10% of individuals and is the third most common reason for consultation in primary care.

Flowers of higher plants are built in a similar pattern: their outermost whorl is composed of sepals, which protect the young bud, thereafter comes a whorl of often colorful petals attracting insect pollinators, followed by a whorl of stamens with pollen sacks and the innermost whorl holds carpels, which later give rise to the fruit and seeds. This basic architecture is comparable in higher plants prompting the question after common components of a genetic ’masterplan’.
During flowering four different types of floral organs need to be formed: sepals, which protect the inner organs; the frequently ornamental petals; stamens, which produce pollen and the carpels. This process is orchestrated by a large number of genes. Scientists have now found that a small molecule, a so-called microRNA, is crucial for the control of floral organs identity, UPI says.
Scientists in the group of Zsuzsanna Schwarz-Sommer investigated a mutant of snapdragon where stamens form instead of petals (see image). Interestingly, a strikingly similar mutant occurs in another plant species, in Petunia.
’We already suspected some ten years ago when we first looked at these mutants that in the two species a similar defect might disturb the genetic control resulting in the ’wrong organ at the wrong place’ explains Mrs. Schwarz-Sommer. A similar example is well known in the fruit fly where a mutant carries a pair of legs at the head instead of the two antennae.
Indeed, experiments performed by the German and Dutch scientists showed that in the two plant species mutation in the same gene conferred altered identity to the floral organs. This gene turned out to code for a microRNA, a small ribonucleic acid consisting of little more than 20 nucleotides.
MicroRNAs can recognize and bind to complementary sequences present in messenger RNAs (mRNA) and prevent thereby translation of the mRNA into a protein: the respective gene falls silent. By this interaction microRNAs can influence whole chains of control events.
Mutations in microRNAs are rare, so this is the first example for the functional similarity of a plant microRNA in two species. Schwarz-Sommer underlines the significance of the work as follows. ’Our novel insights into control mechanisms governing floral organ identity will need to be built into future attempts to model this biological process mathematically.’
The complex control of floral organ identity has been described by the simple ABC model in textbooks.
A, B and C are three developmental functions: A alone is responsible for sepals, combined function of A and B results in petals and combined B and C in stamens.
The identity of the central carpel is solely controlled by C. The new results are in conflict with an important mechanistic prediction of this model and replace a static spatial control by a temporal dynamic one.

How long can you hold your breath? For even highly trained humans, it’s a few minutes, tops. Compare that with the killifish, which can survive without oxygen for more than 60 days, by far the longest of any vertebrate.
Annual killifish, Austrofundulus limnaeus, live in temporary ponds in arid regions of Venezuela. Their embryos ride out seasonal droughts buried in mud, where microbial action often uses up all the oxygen, NewScientist.com
Jason Podrabsky, a comparative physiologist at Portland State University in Oregon, and his colleagues tested killifish embryos by sealing them in oxygen-free vials. After 62 days, half the embryos recovered when given oxygen (The Journal of Experimental Biology, vol 210, p 2253). The next best vertebrates--turtles and a species of goldfish-- can survive for only a few days.
Podrabsky found that longer-lived killifish embryos accumulated lactate--the end product of anaerobic metabolism--very slowly, suggesting that their anaerobic ability comes from being able to cut their metabolic rate to extremely low levels.
Podrabsky is now studying which genes are responsible for the metabolic slowing. Learning how the fish do this may help explain how human tissues respond to anoxia during, say, a heart attack, Podrabsky says.
From issue 2609 of New Scientist magazine, 27 June 2007, page 15

Investigators from the Institute of Research in Biomedicine (IRB Barcelona) have identified a new signalling mechanism among cells in the fruit fly, Drosophila melanogaster. The researchers found that two independent groups of cells generate the same signal by different pathways and that these cells subsequently act together to send the signal to the target cell. In this manner, the receptor cell receives the signal from two distinct sources.
Jordi Casanova (IRB Barcelona/CSIC) explains that different types of cells working together to send a message can be regarded as a “security measure designed to ensure that the signal reaches the receptor cell in the proper fashion, neither too weakly nor too strongly“. Using RNA interference techniques (RNAi), the researchers observed that it was necessary to disactivate the signal in both groups of cells in order to prevent the message from being sent. They also observed that overstimulating signal production (producing more of the signalling molecule) created problems in the receptor cell, causing it to develop incorrectly, eurekalert says.
Researchers made the discovery by studying the behaviour of a gene called torso-like during the early stages of embryonic development of the Drosophila fly. Two groups of cells activated the same torso-like gene separately and by different mechanisms when they were still in separate compartments inside the Drosophila ovary. Subsequently, the cells migrated until they met and jointly signalled the target cell.
Marc Furriols, lead author of the study, explains that the torso-like gene activates a membrane receptor molecule that is specific to Drosophila, but that the molecule belongs to a receptor family (that includes, for example, the human growth factor), which also reacts when it receives an external signal. “This research describes a very signalling mechanism in the fly which is very basic. It gives us good insight into how these mechanisms work so that we can later manipulate and control them.
Many of these pathways and signalling systems have been observed throughout evolution and hence, studies with models such as the fruit fly, can provide further insight into how these signalling mechanisms work in humans.

Northern leopard frog

A synthetic version of a molecule found in the egg cells of the Northern Leopard frog (Rana pipiens) could provide the world with the first drug treatment for brain tumours.
Known as Amphinase, the molecule recognises the sugary coating found on a tumour cell and binds to its surface before invading the cell and inactivating the RNA it contains, causing the tumour to die.
In new research scientists from the University of Bath (UK) and Alfacell Corporation (USA) describe the first complete analysis of the structural and chemical properties of the molecule, Science Daily reported.
Although it could potentially be used as a treatment for many forms of cancer, Amphinase offers greatest hope in the treatment of brain tumours, for which complex surgery and chemotherapy are the only current treatments.
“This is a very exciting molecule,“ said Professor Ravi Acharya, from the Department of Biology & Biochemistry at the University of Bath.
“It is rather like Mother Nature’s very own magic bullet for recognising and destroying cancer cells.
“It is highly specific at hunting and destroying tumour cells, is easily synthesised in the laboratory and offers great hope as a therapeutic treatment of the future.“
Amphinase is a version of a ribonuclease enzyme that has been isolated from the oocytes (egg cells) of the Northern Leopard frog.
Ribonucleases are a common type of enzyme found in all organisms. They are responsible for tidying up free-floating strands of RNA cells by latching on to the molecule and cutting it into smaller sections.
In areas of the cell where the RNA is needed for essential functions, ribonucleases are prevented from working by inhibitor molecules. But because Amphinase is an amphibian ribonuclease, it can evade the mammalian inhibitor molecules to attack the cancer cells.
As a treatment, it is most likely to be injected into the area where it is needed. It will have no effect on other cells because it is only capable of recognising and binding to the sugar coating of tumour cells.
“Amphinase is in the very early stages of development, so it is likely to be several years and many trials before it could be developed into a treatment for patients,“ said Professor Acharya and his colleagues Drs Umesh Singh and Daniel Holloway.
Amphinase is the second anti-tumour ribonuclease to be isolated by Alfacell Corporation from Rana pipiens oocytes.
The other, ONCONASE(R) (ranpirnase), is currently in late-stage clinical trials as a treatment for unresectable malignant mesothelioma, a rare and fatal form of lung cancer, and in Phase I/II clinical trials in non-small cell lung cancer and other solid tumours.

A carabid beetle inserting its head into a snail shell.

Large jaws are efficient in crushing hard prey, whereas small jaws are functional in capturing elusive prey. Researchers have suggested that such trade-offs between “force“ and “velocity“ could cause evolutionary diversification of morphology in animals such as birds, fish, and salamanders.
Junji Konuma and Satoshi Chiba of Tohoku University found that a new trade-off exists in animal feeding behavior. The team suggests that diversification of carabid beetles could be caused by a “force“ and “fit“ trade-off, Science Daily said.
There are both elongate, small-headed and stout, large-headed carabid beetles that feed upon land snails. Large-headed beetles can readily crush snail shells with their powerful jaws, but cannot insert their oversized heads into the shells. In contrast, small-headed beetles can insert their heads into the shells for direct predation on snail bodies, but poorly crush the shells because of their frugal jaws.
“Crushing and inserting are alternatively effective in feeding on snails,“ said Konuma. Carabid beetles that feed on snails tend to have an extremely slender or stout forebody compared with beetles that eat insects and earthworms. Phylogenetic studies show that adaptations for snail feeding led to the diversification of beetle heads.
Interestingly, it has been demonstrated that the same trade-off diversifies shell morphology in studies of freshwater snails, where elongate shells are adaptive in protecting against entry attacks and rounded shells are adaptive in protecting against crushing attacks. “Trade-offs between force and fit have a significant, important role in both morphologies of snails and snail predators in evolution,“ said Konuma.