There have only been 8 transits of Venus between the Sun and the Earth since the invention of the modern telescope, and the next one won’t be until December 2117. The journey lasted just under seven hours, with some of the best images being produced by NASA’s Solar Dynamics Observatory (SDO), which is positioned 36km above the Earth and takes a photograph once every 10 seconds
This is one of the rarest astronomical events in our solar system and occurs in pairs 8 years apart that are either 105 or 121 years apart. The reason for this unusual rate is because the orbits of Earth and Venus orbits are not on the same plane (“angle”). The last transit happened in 2004.
Such an event was important in the 17th and 18th centuries when astronomers wanted to understand the scale of our solar system, and used triangulation to estimate the distance to Venus, which have since been proved to be fairly accurate.
Nowadays, scientists still learn from the transits and use their findings in researching exoplanets. When a planet passes between the instrument “looking” for planets that could harbour life, and a star, they detect a decrease in the light emitted from that star. If the same decrease in light is seen at regular intervals in the future, this indicates an orbit and that planet is considered as a possible source of life beyond our planet, depending on its size, atmosphere properties and its distance from its sun. This technique is how Kepler 22B was identified as an exoplanet last year.
Male fruit flies that have been snubbed by females turn to drink for a reward stimulus to compensate for the lack of sex.
The research, published in Science, highlights neuropeptide F, which has a homolog in humans and is thought to regulate behaviour in a similar way. In humans it is known as neuropeptide Y and has comparisons have already been shown between it and alcohol in mice.
“It is thought that reward systems evolved to reinforce behaviours that are important for the survival of both individuals and species, like food consumption and mating,” said Dr Shohat-Ophir, who led the study.
“Drugs of abuse kind of hijack the same neural pathways used by natural rewards, so we wanted to use alcohol - which is an extreme example of a compound that can affect the reward system - to get into the mechanism of what makes social interaction rewarding for animals.”
The team set up a number of experiments, in one box one male was with five virgin females and were receptive to the male’s advances. In a separate box, a male was placed with females who had already mated and snubbed the approaches of males. The food available to the flies was a choice of their normal food or a substitute that had 15% alcohol. The males who had mated went for the normal food, and the males that had not managed to woo the females tried to drown their sorrows in the 15% alcohol containing food.
Males that had mated were found to have elevated levels of neuropeptide F and therefore didn’t need a “reward” stimulus, compared to the rejected males which had lower levels.
Dr Shohat-Ophir believes the link goes beyond fruit flies and can apply to other animal.
Howevere, Dr Zars wrote an accompanying article in Science, writing:“anthropomorphising the results from flies is difficult to suppress, but the relevance to human behaviour is obviously not yet established”.
Despite the uncertain link to human social behaviour, it could perhaps lead the way in understanding drug abuse in humans and ways to combat it.
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A new species of chameleon has been discovered in Madagascar.
The tiny species grow to a maximum of 2.9cm and infants can stand on the head of a match. The team, headed by Dr. Glaw, discovered Brookesia micra on the North Island of Madagascar, along with three other species. They say that there could be a “two island effect”, in which the main island has produced a group of dwarf chameleons and a very small island has produced the tiny species. This phenomenon is not unusual and causes species to diverge over evolutionary time and the population on the small island become smaller due to limited habitat on an island.
Genetic analysis was conducted on the four species and it was determined that they diverge from each other millions of years ago.
They also found that each species occupies a habitat of only one square kilometre for the smallest species, meaning that these are particularly vulnerable to environmental changes and habitat disturbances. The animals live in the leaf litter during the day and climb the trees at night to sleep.
The researchers chose thought provoking names for the new species including B. Tristis (named after the French word “triste” meaning sad, was found near the edge of an expanding city) and Brookesia desperata (named for the “desperate” loss of habitat the species has suffered) as an expression of the concern for Madagascar’s fragile habitats.
Cancer is caused by an accumulation of mutations in one cell. No one mutation is sufficient to cause cancer on its own. There are six hallmarks of cancer, each of which must be present in order for a fully-fledged cancer to develop. Below they are described and explained in a way (hopefully) anyone can understand.
A mutation in a gene causes cancer cells must be self-sufficient in growth signals. Growth Factors that are produced by tumour cells act back on the tumour cells, causing proliferative growth and the establishment of a positive feedback loop. This is where the Growth Factors cause the cell to grow, which produces more Growth Factors, which act back on the tumour cell again, causing a vicious cycle.
Cancer cells must also be insensitivity to growth inhibitory signals. If DNA damage is sensed during replication, the cell cycle is arrested until the damage is repaired or the cell dies. In cancer cells, this regulation is absent, causing genetically aberrant cells to pass through the cell cycle without the damage being repaired. This causes an accumulation of mutant cells.
Cancer cells are able to evade apoptosis (controlled cell death). When cells become damaged there is usually a gene that causes such cells to either be repaired or undergo controlled suicide. Tumour cells cannot sense DNA damage and as such cannot repair the damage or send the cell for destruction. This causes mutant cells to accumulate. The mutation rate in mutated cells is higher than that of normal cells, meaning there is a rapid accumulation of tumour cells, contributing to the development of cancer.
Normal cells can divide about sixty times before they die. The ends of the DNA are protected by repetitive regions called telomeres. When DNA is damages, telomeres degrade to a threshold of about 3,000 bases long, the cells enter crisis and die if the telomere length is not restored. Cancer cells can produce telomerase, an enzyme that forms telomeres and maintains them just above the crisis point. This means that despite having DNA damage, the telomeres will not degrade to the crisis point and the cells are immortal, allowing the accumulation of mutant cells.
Without their own blood vessels, tumours reach a max of 1mm3, at which point they send out signals which recruit blood vessel building machinery to create their own blood supply through the process of angiogenesis. This allows the tumour to grow, and as it does, more of its centre becomes hypoxic (without oxygen), which drives the perpetuation of angiogenesis.
Parts of the primary tumour (the original site of mutant cells) can break off and travel through the circulation to a distant site. If this attaches and becomes established here, it can begin to grow and form a metastatic tumour. Tumours often become established in sites that have a good blood and nutrient supply, e.g. the liver, and are in direct contact (through the circulation) with the primary site (e.g. prostate cancers often metastasise to bones).
This is a fully-fledged cancer now as all six hallmarks are present:
1) Self sufficiency in growth signals
2) Insensitivity to growth inhibitory signals
3) Limitless replicative potential (immortality)
4) Evading apoptosis (not undergoing suicide when damaged)
5) Sustained angiogenesis (the tumour having its own blood supply)
6) Metastasis (part of the primary tumour established in a distant second site).
Image: Breast cancer cell http://tinyurl.com/7tpka7a
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Image: Print screen from the same website.
Advances in the area of genetic testing need to be utilised in the NHS, says a report by Prof Sir John Bell.
Genetic testing for certain bowel and breast cancers is currently used, but the rapid fall in the prices of decoding a patient’s genome has meant that it is looking more and more like an option for regular use in hospitals.
For example, breast cancer has always been defined because of a tumour in the breast. But, at a molecular level, it can closer resemble other cancers (like ovarian cancer) meaning that a different treatment regime would be more effective than the standard breast cancer treatment. A few years ago, the “million dollar genome” was thought to be cheap, now a whole human genome can be screened for $1,000. Prof Sir John Bell said that this rapid drop in price means that soon, the cost will “essentially be nothing”. It is with this that the report is urging the British government to prepare the NHS for the “revolution” in technology and embrace the technological advances for the good of patients, healthcare and financial interests in hospitals.
He also calls for current staff to be trained in Genetics so they can be prepared for the changes expected to sweep across the NHS.
The government is yet to respond formally to the report, but the health secretary Andrew Lansely said “We want to make sure that all patients can benefit from these tests - as soon as the tests are recommended by NICE”. He later added that the potential in the field was “immense”.
Stem cell technology could provide the answer to solve the world’s hunger problem.
For example, pig stem cells would be taken and stimulated to for muscle cells, which are grown on a scaffold with the needed nutrients and “exercised” through electrical stimulation or mechanical stretchers. These cells could then be shaped and seasoned into sausages, burgers, etc.
Meat production is one of the main contributors to global warming, deforestation, and a lack of fresh water and biodiversity. Twenty percent of the greenhouse gases produced is as a result of meat production and farming animals for food takes up one third of total land area in the world.
So engineered food would have more than one benefit of feeding the hungry, it would reduce overcrowding as less area would be needed by animals, and it would reduce the effects of global warming. Cultured meat has 80-95% lower greenhouse gas emissions, 99% lower land use and 80-90% lower water use compared to conventionally produced meat in Europe, a recent study found.
The land freed up by growing engineered meat could be used to grow new forests and thus increase the reversal of global warming. It would also prevent illegal poaching for rare meat as these animals could also be used to create engineered meat and would remove the unethical treatment of animals kept in captivity for the production of food, such as battery hens.
The meat could be engineered to have a controlled amount of fat in, so fat-free meat, or meat that contains “good” fats could be grown. The risk of zoonotic diseases spread from animals to humans would also be eradicated.
The ability to screen a person’s entire genome has taken a step closer to being affordable for routine use after an American Biotechnology company announced they have built an instrument that can decode the entire genome for around £650.
Such technology will allow patients to be screened to determine their predisposition to certain diseases, such as Alzheimer’s, Cancers, Heart Disease and Diabetes. It originally cost £1.9billion to sequence the human genome and hundreds of scientists years. Then, in 2009, the “$1 million genome” was announced and quickly undercut by another scientist who had mapped his own genome for $50,000, in 2010.
Life Technologies, the company behind the latest technology, say that their instrument can decipher a patient’s entire genome in one day, bringing it closer to the timescale needed for diagnostic medicine.
Being aware of and understanding such genetic risks is vital in lifestyle changes, regular screening and early treatment therapy, thus saving lives through preventative measures, rather than curative ones.
But unlocking the mysteries of the genome will have its problems. Who should have access to these results? Clearly, insurance companies and employers have an interest in the long term health of a person, but should the information gained from breakthrough technology be undermined by the economic interests of others? Also, for the patient involved, it may have adverse affects if they are aware of what they are probably going to die of, and possibly what they have unknowingly passed onto their children.