Science News Digest 9th August 2010
In the science news this week, we look at the agility of male spiders, find out that it may not be simply a poor diet that increases the risk of heart disease, learn how cloned meat has entered the UK food chain, take a look at an ancient crocodile ancestor... and finally, hear news that spicy food may be good for our health.
Spider Men
Scientists from the Spanish National Research Council have been trying to answer the question as to why in many species of spider, the male is much smaller than the female.
It appears that over time evolution has favoured larger females as they are able to reproduce more efficiently. The same is not true for male spiders, and the researchers suggest that by remaining small, the male spiders are able to maintain a higher level of mobility. The large difference in size between the male and female spiders is an example of extreme sexual size dimorphism.
Spiders are able to move between plants by producing a strand of silk and allowing the wind to attach it to a distant leaf. The spider then secures the other end and uses this strand to traverse the gap, moving on the underside of the silk. This movement is known in the study as “bridging”.
The team of scientists tested 204 spiders from 13 different species, each showing extreme dimorphism, and found that the smaller male spiders were most successful at bridging due to their reduced size and weight, and are therefore likely to enjoy more mating opportunities than heavier spiders.
This research sheds new light on the evolutionary pressure that keeps some male spiders small. Previously it was speculated that males remained small to aid their escape from predators, or allow them better access to mates. This is the first research that looked at ability of male spiders to traverse gaps.
"A selective pressure against large male body size has been searched for by researchers since Darwin; the constraint on bridging seems to be such a selective pressure," said Dr. Guadalupe Corcobado, who lead the research.
Full story at the BBC
--------------------
Working towards healthy hearts
Scientists from the USA have revealed a number of genetic markers which may help to explain why some individuals are predisposed to heart disease, whilst others are able to eat unhealthily with no increased risk.
Blood samples from 100,000 people worldwide were taken, with the amount of fat in their blood stream tested, and their DNA scanned to look for areas that affect blood fat levels.
95 individual locations of DNA were identified that were involved with the increase or decrease of blood fats, 59 of which were unknown before the study.
Fats in blood can take the form of cholesterol or triglycerides. These are very important in the formation of cell membranes, but an incorrect balance in either can cause serious medical conditions.
Cholesterol comes in two varieties, low density lipoprotein (LDL) and high density lipoprotein (HDL). LDL can build up in arteries, causing blockages, whilst HDL can remove fatty deposits.
13 of the identified DNA regions appear to be directly involved with increasing the risk of heart disease, most by raising the level of LDL. One area, carried by about 20 of the population, leads to a small but significant lowering of LDL. This may allow those who carry it to eat higher fat foods without an increased risk of heart disease.
Full story at the Independent
--------------------
Making a meal out of it?
Meat from a cloned cow has entered the British food chain, the Food Standards Agency (FSA) has revealed.
Whilst researching allegations that milk from the offspring of a cloned cow had been sold in the UK, the FSA identified two bulls, named Dundee Paratrooper and Dundee Perfect, which were born in the UK from cloned embryos imported from the US. The first bull was born in 2006 and was slaughtered in 2009. Meat from this animal is likely to have been consumed. The second bull was slaughtered in July 2010, but the meat was intercepted before entering the food chain.
Meat and milk from cloned animals is considered a ‘novel food’ in the UK, and cannot be sold without authorisation. There is no such requirement in the US where the sale of cloned meat is legal, and has been described in 2008 by the Food and Drug Administration (FDA) as indistinguishable from non-cloned meat.
A 2005 study performed by scientists in Japan and the US showed that whilst meat from cloned cows contained slightly higher fat and fatty acids than meat from non-cloned cows, the levels were well within accepted standards.
The research concluded that cloned meat and milk were safe for human consumption. Opponents of the consumption of cloned animal produce say that not enough research exists to definitively prove that it is safe.
It is not known how many descendants of cloned cows are in the UK, as there are no restrictions on the importing of cloned cow semen.
Cloning an animal uses a process known as ‘somatic nuclear transfer’. This involves taking an animal egg, removing the nucleus and replacing it with the nucleus from a cell of the animal that is to be cloned. This cloned cell then begins to divide into an embryo which can be implanted into a surrogate.
Full story at the BBC
--------------------
The smile of an ancient crocodile
Palaeontologists from Ohio University have uncovered the remains of an ancient crocodile with a very interesting jaw structure.
The fossil, found in an ancient river bed, in what is now the Mbeya region of Tanzania, is believed to be 105 million years old. This species is very unlike modern crocodiles, with a small head, and fewer bony plates, suggesting it was a more agile creature. The species has been named Pakasuchus kapilimai. 'Paka' is Swahili for cat, whilst the Greek for crocodile is 'Suchus'. This name gives an idea as to the size of the animal, whose head would have fit in the palm of your hand.
What is interesting about this particular fossil is the composition of its teeth. Unlike modern crocodiles, which have cone shaped teeth used for tearing flesh, this ancient animal had a jaw structure closer to a mammal than a reptile, with primitive canines, premolars and molars. The skull of the fossil was completely encased with rock, with its jaws firmly shut, so the team had to use X-ray computed tomography to reveal the details of the teeth and jaws.
"Once we were able to get a close look at the teeth, we knew we had something new and very exciting," said Patrick O'Connor who led the study.
The animal also appears to have had a very flexible backbone, and probably had a diet of insects and other small animals.
Full story at the Guardian
--------------------
Hot Stuff
Capsaicin, the active ingredient in chilies that gives spicy food its bite, reduces blood pressure in rats, say Chinese scientists.
The scientists tested long term exposure of rats, genetically predisposed to hypertension, to capsaicin. This exposure appeared to lower blood pressure by activating chemical “channels” found in the lining of blood vessels. These activated channels led to an increase in levels of nitric oxide (NO) in the blood vessels. NO is believed to be involved with protection against vascular inflammation.
Previous studies have been inconclusive in proving whether chilies can reduce blood pressure, but these studies have been much shorter in length than the current study.
Epidemiological studies in humans need to be undertaken to look for links between human capsaicin consumption and blood pressure problems. Dr. Zhiming Zhu of Third Military Medical University in Chongqing, who lead the study, says there may be evidence from China to support the case. Rates of hypertension are approximately 20% in north-eastern areas of China, whilst in south-western regions, where spicy foods are more common, the rates of hypertension are lower, between 10 and 14%.
Thankfully, Dr. Zhu indicates that those of us who don’t enjoy spicy food may still be able to enjoy the benefits of chilies. Limited studies show that the compound capsinoid, found in milder chilies, and related to capsaicin, may also have a similar effect on blood pressure.
Full story at the Independent
--------------------
Spider Men
Scientists from the Spanish National Research Council have been trying to answer the question as to why in many species of spider, the male is much smaller than the female.
It appears that over time evolution has favoured larger females as they are able to reproduce more efficiently. The same is not true for male spiders, and the researchers suggest that by remaining small, the male spiders are able to maintain a higher level of mobility. The large difference in size between the male and female spiders is an example of extreme sexual size dimorphism.
Spiders are able to move between plants by producing a strand of silk and allowing the wind to attach it to a distant leaf. The spider then secures the other end and uses this strand to traverse the gap, moving on the underside of the silk. This movement is known in the study as “bridging”.
The team of scientists tested 204 spiders from 13 different species, each showing extreme dimorphism, and found that the smaller male spiders were most successful at bridging due to their reduced size and weight, and are therefore likely to enjoy more mating opportunities than heavier spiders.
This research sheds new light on the evolutionary pressure that keeps some male spiders small. Previously it was speculated that males remained small to aid their escape from predators, or allow them better access to mates. This is the first research that looked at ability of male spiders to traverse gaps.
"A selective pressure against large male body size has been searched for by researchers since Darwin; the constraint on bridging seems to be such a selective pressure," said Dr. Guadalupe Corcobado, who lead the research.
Full story at the BBC
--------------------
Working towards healthy hearts
Scientists from the USA have revealed a number of genetic markers which may help to explain why some individuals are predisposed to heart disease, whilst others are able to eat unhealthily with no increased risk.
Blood samples from 100,000 people worldwide were taken, with the amount of fat in their blood stream tested, and their DNA scanned to look for areas that affect blood fat levels.
95 individual locations of DNA were identified that were involved with the increase or decrease of blood fats, 59 of which were unknown before the study.
Fats in blood can take the form of cholesterol or triglycerides. These are very important in the formation of cell membranes, but an incorrect balance in either can cause serious medical conditions.
Cholesterol comes in two varieties, low density lipoprotein (LDL) and high density lipoprotein (HDL). LDL can build up in arteries, causing blockages, whilst HDL can remove fatty deposits.
13 of the identified DNA regions appear to be directly involved with increasing the risk of heart disease, most by raising the level of LDL. One area, carried by about 20 of the population, leads to a small but significant lowering of LDL. This may allow those who carry it to eat higher fat foods without an increased risk of heart disease.
Full story at the Independent
--------------------
Making a meal out of it?
Meat from a cloned cow has entered the British food chain, the Food Standards Agency (FSA) has revealed.
Whilst researching allegations that milk from the offspring of a cloned cow had been sold in the UK, the FSA identified two bulls, named Dundee Paratrooper and Dundee Perfect, which were born in the UK from cloned embryos imported from the US. The first bull was born in 2006 and was slaughtered in 2009. Meat from this animal is likely to have been consumed. The second bull was slaughtered in July 2010, but the meat was intercepted before entering the food chain.
Meat and milk from cloned animals is considered a ‘novel food’ in the UK, and cannot be sold without authorisation. There is no such requirement in the US where the sale of cloned meat is legal, and has been described in 2008 by the Food and Drug Administration (FDA) as indistinguishable from non-cloned meat.
A 2005 study performed by scientists in Japan and the US showed that whilst meat from cloned cows contained slightly higher fat and fatty acids than meat from non-cloned cows, the levels were well within accepted standards.
The research concluded that cloned meat and milk were safe for human consumption. Opponents of the consumption of cloned animal produce say that not enough research exists to definitively prove that it is safe.
It is not known how many descendants of cloned cows are in the UK, as there are no restrictions on the importing of cloned cow semen.
Cloning an animal uses a process known as ‘somatic nuclear transfer’. This involves taking an animal egg, removing the nucleus and replacing it with the nucleus from a cell of the animal that is to be cloned. This cloned cell then begins to divide into an embryo which can be implanted into a surrogate.
Full story at the BBC
--------------------
The smile of an ancient crocodile
Palaeontologists from Ohio University have uncovered the remains of an ancient crocodile with a very interesting jaw structure.
The fossil, found in an ancient river bed, in what is now the Mbeya region of Tanzania, is believed to be 105 million years old. This species is very unlike modern crocodiles, with a small head, and fewer bony plates, suggesting it was a more agile creature. The species has been named Pakasuchus kapilimai. 'Paka' is Swahili for cat, whilst the Greek for crocodile is 'Suchus'. This name gives an idea as to the size of the animal, whose head would have fit in the palm of your hand.
What is interesting about this particular fossil is the composition of its teeth. Unlike modern crocodiles, which have cone shaped teeth used for tearing flesh, this ancient animal had a jaw structure closer to a mammal than a reptile, with primitive canines, premolars and molars. The skull of the fossil was completely encased with rock, with its jaws firmly shut, so the team had to use X-ray computed tomography to reveal the details of the teeth and jaws.
"Once we were able to get a close look at the teeth, we knew we had something new and very exciting," said Patrick O'Connor who led the study.
The animal also appears to have had a very flexible backbone, and probably had a diet of insects and other small animals.
Full story at the Guardian
--------------------
Hot Stuff
Capsaicin, the active ingredient in chilies that gives spicy food its bite, reduces blood pressure in rats, say Chinese scientists.
The scientists tested long term exposure of rats, genetically predisposed to hypertension, to capsaicin. This exposure appeared to lower blood pressure by activating chemical “channels” found in the lining of blood vessels. These activated channels led to an increase in levels of nitric oxide (NO) in the blood vessels. NO is believed to be involved with protection against vascular inflammation.
Previous studies have been inconclusive in proving whether chilies can reduce blood pressure, but these studies have been much shorter in length than the current study.
Epidemiological studies in humans need to be undertaken to look for links between human capsaicin consumption and blood pressure problems. Dr. Zhiming Zhu of Third Military Medical University in Chongqing, who lead the study, says there may be evidence from China to support the case. Rates of hypertension are approximately 20% in north-eastern areas of China, whilst in south-western regions, where spicy foods are more common, the rates of hypertension are lower, between 10 and 14%.
Thankfully, Dr. Zhu indicates that those of us who don’t enjoy spicy food may still be able to enjoy the benefits of chilies. Limited studies show that the compound capsinoid, found in milder chilies, and related to capsaicin, may also have a similar effect on blood pressure.
Full story at the Independent
--------------------
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