Category Archives: Biology
All cancer is man-made, say scientists
Emma Woollacott
Cancer is a modern disease caused by factors such as pollution and diet, a study of ancient human remains has indicated.
The study of remains and literature from ancient Egypt, ancient Greece and earlier periods shows almost no evidence of the disease, says Professor Rosalie David of the University of Manchester.
Only one case has been discovered during the investigation of hundreds of Egyptian mummies, and there are few references to cancer in historical records. Cancer, and particularly child cancer, has become vastly more prevalent since the Industrial Revolution.
“In industrialised societies, cancer is second only to cardiovascular disease as a cause of death. But in ancient times, it was extremely rare,” says David. “It has to be a man-made disease, down to pollution and changes to our diet and lifestyle.”
The data includes the first ever histological diagnosis of cancer in an Egyptian mummy by Professor Michael Zimmerman of Villanova University, who found rectal cancer in an unnamed mummy from the Ptolemaic period.
“In an ancient society lacking surgical intervention, evidence of cancer should remain in all cases,” says Zimmerman. “The virtual absence of malignancies in mummies must be interpreted as indicating their rarity in antiquity, indicating that cancer causing factors are limited to societies affected by modern industrialization”.
It”s not just that people didn”t live long enough to get cancer, says the team, as individuals in ancient Egypt and Greece did still develop such diseases as atherosclerosis, Paget”s disease of bone, and osteoporosis.
Nor do tumors simply fail to last. Zimmerman”s experiments indicate that mummification preserves the features of malignancy, and that tumours should actually be better preserved than normal tissues.
The first reports in scientific literature of distinctive tumours have only occurred in the past 200 years, such as scrotal cancer in chimney sweeps in 1775, nasal cancer in snuff users in 1761 and Hodgkin’s disease in 1832.
“Extensive ancient Egyptian data, along with other data from across the millennia, has given modern society a clear message – cancer is man-made and something that we can and should address,” says David.
http://www.tgdaily.com/general-sciences-features/52036-all-cancer-is-man-made-say-scientists
Gene''s Location on Chromosome Plays Big Role in Shaping How an Organism''s Traits Evolve
New research shows that a gene”s location on a chromosome plays a significant role in shaping how an organism”s traits vary and evolve. (Credit: iStockphoto/Liang Zhang)
gene”s location on a chromosome plays a significant role in shaping how an organism”s traits vary and evolve, according to findings by genome biologists at New York University”s Center for Genomic and Systems Biology and Princeton University”s Lewis-Sigler Institute for Integrative Genomics. Their research, which appears in the latest issue of the journal Science, suggests that evolution is less a function of what a physical trait is and more a result of where the genes that affect that trait reside in the genome.
Physical traits found in nature, such as height or eye color, vary genetically among individuals. While these traits may differ significantly across a population, only a few processes can explain what causes this variation — namely, mutation, natural selection, and chance.
In the Science study, the NYU and Princeton researchers sought to understand, in greater detail, why traits differ in their amount of variation. But they also wanted to determine the parts of the genome that vary and how this affects expression of these physical traits. To do this, they analyzed the genome of the worm Caenorhabditis elegans (C. elegans). C. elegans is the first animal species whose genome was completely sequenced. It is therefore a model organism for studying genetics. In their analysis, the researchers measured approximately 16,000 traits in C. elegans. The traits were measures of how actively each gene was being expressed in the worms” cells.
The researchers began by asking if some traits were more likely than others to be susceptible to mutation, with some physical features thus more likely than others to vary. Different levels of mutation indeed explained some of their results. Their findings also revealed significant differences in the range of variation due to natural selection — those traits that are vital to the health of the organism, such as the activity of genes required for the embryo to develop, were much less likely to vary than were those of less significance to its survival, such as the activity of genes required to smell specific odors.
However, these results left most of the pattern of variation in physical traits unexplained — some important factor was missing.
To search for the missing explanation, the researchers considered the make-up of C. elegans” chromosomes — specifically, where along its chromosomes its various genes resided.
Chromosomes hold thousands of genes, with some situated in the middle of their linear structure and others at either end. In their analysis, the NYU and Princeton researchers found that genes located in the middle of a chromosome were less likely to contribute to genetic variation of traits than were genes found at the ends. In other words, a gene”s location on a chromosome influenced the range of physical differences among different traits.
The biologists also considered why location was a factor in the variation of physical traits. Using a mathematical model, they were able to show that genes located near lots of other genes are evolutionarily tied to their genomic neighbors. Specifically, natural selection, in which variation among vital genes is eliminated, also removes the differences in neighboring genes, regardless of their significance. In C. elegans, genes in the centers of chromosomes are tied to more neighbors than are genes near the ends of the chromosomes. As a result, the genes in the center are less able to harbor genetic variation.
The research was conducted by Matthew V. Rockman, an assistant professor at New York University”s Department of Biology and Center for Genomics and Systems Biology as well as Sonja S. Skrovanek and Leonid Kruglyak, researchers at Princeton University”s Lewis-Sigler Institute for Integrative Genomics, Department of Ecology and Evolutionary Biology, and Howard Hughes Medical Institute.
The study was supported by grants from the National Institutes of Health.
Story Source:
The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by New York University.
Journal Reference:
- M. V. Rockman, S. S. Skrovanek, L. Kruglyak. Selection at Linked Sites Shapes Heritable Phenotypic Variation in C. elegans. Science, 2010; 330 (6002): 372 DOI: 10.1126/science.1194208
http://www.sciencedaily.com/releases/2010/10/101014144312.htm
The platypus knows 80 different ways to poison you
Genome analysis shows that the monotremes and snakes have similar venoms.
By Ewen Callaway
Don””t be fooled by the playful-looking duck””s bill — platypuses deliver a venom containing more than 80 different toxins.
The finding, from an analysis of the genes encoding the dangerous mixture, also reveals the striking similarities between the poisons of different animals. The genes resemble those of other venomous animals, such as snakes, lizards, starfish and sea anemones.
Like eyes, fins and wings, which have evolved independently in a number of different lineages, platypus venom looks to be an example of convergent evolution, says Wesley Warren, a genomicist at Washington University in St Louis, Missouri, who led the study, published in the journal Genome Biology.1
The platypus — a semi-aquatic egg-laying mammal found in Australia — is one of few mammals to make venom, which males produce in abdominal venom glands and deliver through spurs on their hind legs. They only make the poison during breeding season, and Warren thinks that males probably deploy it to defend their turf against other males.
By some accounts, being poisoned by a platypus could qualify as punishment in one of Dante””s circles of hell. In one case report2, Australian doctors described their treatment of a 57-year-old man a few hours after he grabbed one of the small mammals while fishing. The pain was “so bad I started to become incoherent” the man said, and far worse than the shrapnel wounds he took as a soldier. Ibuprofen and morphine provided no relief, and one finger was swollen and ached more than 4 months after the run-in.
Efforts to find the molecules capable of inflicting such anguish have focused on separating and characterizing proteins in venom extracts. This approach identified three of the most abundant ingredients of platypus venom, but Warren””s team suspected that more molecules were present at lower levels.
What””s your poison?
His team sequenced messenger RNA transcripts from the venom gland of a male platypus, killed by a dog in breeding season. To identify venom ingredients they looked for genes that were not produced in other tissues and which resembled venom genes from other animals. This scan turned up 83 genes in 13 different families of toxins, linked to effects including inflammation, nerve damage, muscle contraction and blood coagulation. For instance, platypuses make 26 different kinds of serine protease enzymes, which are also found in the venom of most snakes, and seven of their venom genes resemble a neurotoxin produced by spiders called α-latrotoxin.
Additional tests will be needed to determine what each venom ingredient does, says Warren. He also thinks that his team””s study undercounted the number of toxin-encoding genes in the platypus ””venome””, because the method used overlooks genes that bear little resemblance to other animal toxins. To find these, his team plans to look for genes switched on during the seasonal development of the platypus venom gland.
Nonetheless, the platypus venome supports work in other animals showing widespread convergence in venom gene evolution. Warren says that this probably happens when genes that perform normal chores, such as blood coagulation, become duplicated independently in different lineages, where they evolve the capacity to carry out other jobs.
Animals end up using the same genes as building blocks for venom because only a subset of the proteins the genes encode have the structural and functional properties to become venoms, he adds.
Despite such convergence, closely related animals tend to produce similar venoms, says Bryan Fry, head of the venomics laboratory at the University of Melbourne, Australia.
An evolutionary outlier such as the platypus is likely to produce a venom with new components, says Fry. “If you want to find something potentially useful in drug design and development from a venom, you””re much likelier to find it in a novel venom such as platypus venom than if you are looking at, say, rattlesnakes.”
Corrected:
An earlier version of this story stated incorrectly that platypuses were marsupials. They are monotremes.
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References
http://www.nature.com/news/2010/101012/full/news.2010.534.html?s=news_rss
http://io9.com/5663979/the-platypus-knows-80-different-ways-to-poison-you
Genetically Engineered Silkworms Spin Like Spiders
The new silk alone could shake up the textile industry by creating a softer and stronger fabric that still looks like silk. Click to enlarge this image. Hemera
Silkworms have been modified to produce spider silk, creating a fabric that could be used in everything from bulletproof clothing to artificial tendons.
By Eric Bland
- Silkworms have been genetically engineered to spin spider silk.
- The new hybrid silk is finer and tougher than ordinary silk.
- The development could lead to wound-healing, lighter body armor as well as artificial tissue.
If Spider-Man ever ran out of webs, he could now enlist an army of silkworms to spin extra high-tensile spider silk.
Scientists have created a genetically modified silkworm that spins a new kind of silk: a hybrid of silkworm silk and spider silk.
The new material alone could shake up the textile industry, while future silk hybrids could be used in everything from bulletproof clothing to artificial tendons.
“Compared to normal spider silk, it””s not as strong,” said Malcolm Fraser, a scientist from the University of Notre Dame. “But we are confident that, this being our first attempt, that we will be able to tweak the system to bring the system closer to the strength of true spider silk.”
Fraser, along with professor Randy Lewis from the University of Wyoming, developed the spider-silk-spinning silkworms.
Silkworms have helped clothe people for thousands of years by reliably producing large quantities of a soft, supple and luxurious material.
Spider dragline silk is significantly stronger than silkworm silk — so strong that it can best steel wire — but it is hard to make.
“They just don””t produce enough silk,” said Fraser, who notes that a golden cloth on display at the American Museum of Natural History in New York City required more than one million spiders to produce. “One million silkworms can produce considerably more silk than one million spiders.”
The new silk is a hybrid of spider silk and silkworm silk. It is stronger and finer than silkworm silk, but not quite as strong as spider silk. “It would definitely be stronger (than a normal silk shirt),” said Lewis. “But it wouldn””t flow like silkworm silk does.”
“It””s a fabulous accomplishment,” said Cheryl Hayashi, a spider silk expert and a professor at the University of California, Riverside.
Other groups have produced spider silk protein in plants, in bacteria and even in goat””s milk. But spider silk protein is not the same as spun spider silk. The silkworms have the necessary body parts to spin the protein into silk threads — and to produce it in large quantities.
The new silk alone could shake up the textile industry by creating a softer, stronger fabric that still looks like silk.
Fraser and his team, however, have bigger plans in mind.
In this work the Notre Dame and University of Wyoming scientists replaced only one of multiple silk-producing genes in silkworms with spider silk genes. Eventually they want to replace multiple silkworm silk-producing genes with spider silk genes.
In particular, they hope to insert genes from the newly discovered Darwin””s Bark Spider (Caerostris darwini), which produced silk twice as strong as any other. That””s more than 10 times stronger than Kevlar, a fabric commonly found in bulletproof vests.
Mass produced, stronger-than-steel spider silk will also have a range of biomedical applications, said Fraser and Lewis. Hybrid silk could be speed wound-healing, eliminate or reduce the need for cadaver-derived tendons and ligaments.
http://news.discovery.com/tech/spider-silk-silkworms-genetic-engineering.html
Surprising Ant "Mixing Bowl" Found in Manhattan
Photograph by Mark Lennihan, AP – People bustle around the intersection of Broadway and 43rd Street in New York City (file photo).Christine Dell””Amore
Published October 13, 2010
An unexpected cast of characters has found a home on Broadway: At least 13 species of ants mingle along the famous thoroughfare and other Manhattan streets, a new study says.
This insect diversity surprised scientists, who discovered the many ants living on street medians in New York City, the United States”” largest metropolis.
Just like human New Yorkers, the ants are a jumble of personalities, from the tiny thief ant—which, as the name suggests, feeds its colonies with stolen food—to the street-smart pavement ant, a fiercely territorial insect that nests under cement. (See ant pictures in National Geographic magazine.)
Though most of the species are native to North America, the team also found a few foreign species living peacefully among the locals, likely having hitched a ride to the Big Apple in soil from potted plants or wood mulch.
For instance, the poisonous Asian needle ant had never before been found north of Virginia. (Also see “Brain-Controlling Flies to Triumph Over Alien Ants?“)
Not all alien species are detrimental to native species. “Quite the opposite,” study leader Marko Pećarević, a Columbia University ecologist, said in an email. “Given enough time—centuries or millennia—they tend to complement the native richness.
“The problem is that one in a hundred will be an invasive, and cause great damage to the environment, usually by altering habitats and/or directly killing other species,” he added.
Despite this rich diversity, for ants Manhattan is more a mixing bowl than a melting pot, the study authors noted.
“While we humans all belong to the same species and hence can reproduce and ””melt”” our ancestral differences into a beautiful amalgam that is New York, the ants that make up the diversity found on the medians in NYC are truly different species and cannot reproduce, but merely mix and coexist,” Pećarević said.
(Related: “Ants Practice Nepotism, Study Finds.”)
Ants Adapting to City Life
In the summer of 2006, Pećarević and colleagues trapped ants on 44 medians along Broadway, Park Avenue, and the West Side Highway on Manhattan Island. (See pictures of what Manhattan may have looked like in 1609.)
All the medians supported some type of vegetation, from the well-manicured lawns of Park Avenue to the tree-lined patches on Broadway, he said by email.
Since past studies of urban wildlife have focused mostly on areas that more closely mimic nature, such as gardens, observing medians or other built elements could reveal unknown animal habitats, the study said.
Predictably, the larger medians host more species, he said. Some species, such as the pavement ant, prefer medians with more concrete.
Others, such as the Asian Nylanderia flavipes, like areas with more trees, according to the study, which appeared October 5 in the journal PLoS One.
Still other ants live underground, including the cornfield ant, which “herds” aphids like people care for cattle.
Future studies that collect ants from trees may reveal additional species in New York City, for a total of about 30, Pećarević predicted.
Eric Lonsdorf, director of the Urban Wildlife Institute at Chicago””s Lincoln Park Zoo, said he was surprised by how many species were discovered in such small strips of land.
Lonsdorf was also intrigued by the idea of ants adapting to life in the city. For instance, past research has shown that odorous house ants living in cities set up larger colonies with multiple queens, according to the study.
Seeing “urban as a particular kind of habitat for animals, rather than universally unsuitable, is a shift in thinking,” Lonsdorf added.
City Critters Poorly Understood
The new research is a reminder that the pockets of nature urbanites encounter each day remain poorly understood—even as more people move into New York and other cities, the study says.
Indeed, finding such an assortment of ants in a city of eight million humans is “more evidence that we know little about how animals perceive urban areas as habitat,” Lonsdorf said.
According to study leader Pećarević, urban wildlife does a “lot of work that makes life more pleasant for us, such as waste removal, seed dispersal, [and] pollination of flowers, to mention but a few.”
So the next time you””re downtown, “take a few minutes to sit on a bench and look at ants go about their business,” he suggested.
“There is a whole new world to discover out there.”
Microchip Technology Rapidly Identifies Compounds for Regrowing Nerves in Live Animals
MIT engineers have developed a way to rapidly perform surgery on single nerve cells in the worm C. elegans. The white lines represent axons — long extensions of nerve cells that carry messages to other cells. (Credit: Craig Millman and Yanik Lab)
Scientists have long sought the ability to regenerate nerve cells, or neurons, which could offer a new way to treat spinal-cord damage as well as neurological diseases such as Alzheimer”s or Parkinson”s. Many chemicals can regenerate neurons grown in Petri dishes in the lab, but it”s difficult and time-consuming to identify those chemicals that work in live animals, which is critical for developing drugs for humans.
Engineers at MIT have now used a new microchip technology to rapidly test potential drugs on tiny worms called C. elegans, which are often used in studies of the nervous system. Using the new technology, associate professor Mehmet Fatih Yanik and his colleagues rapidly performed laser surgery, delivered drugs and imaged the resulting neuron regrowth in thousands of live animals.
“Our technology helps researchers rapidly identify promising chemicals that can then be tested in mammals and perhaps even in humans,” says Yanik. Using this technique, the researchers have already identified one promising class of neuronal regenerators.
Article Continues -> http://www.sciencedaily.com/releases/2010/10/101011173253.htm
Promising Drug Candidate Reverses Age-Related Memory Loss in Mice
A new experimental compound that can improve memory and cognitive function in aging mice, researchers report. (Credit: iStockphoto)
Researchers at the University of Edinburgh report a new experimental compound that can improve memory and cognitive function in aging mice. The compound is being investigated with a view to developing a drug that could slow the natural decline in memory associated with aging.
With support from a Wellcome Trust Seeding Drug Discovery award, the team has identified a preclinical candidate that they hope to take into human trials within a year.
Many people find they become more forgetful as they get older and we generally accept it as a natural part of the aging process. Absent mindedness and a difficulty to concentrate are not uncommon, it takes longer to recall a person”s name, and we can”t remember where we left the car keys. These can all be early signs of the onset of dementia, but for most of us it”s just part of getting old.
Such memory loss has been linked with high levels of ”stress” steroid hormones known as glucocorticoids which have a deleterious effect on the part of the brain that helps us to remember. An enzyme called 11beta-HSD1 is involved in making these hormones and has been shown to be more active in the brain during aging.
In a study published in the Journal of Neuroscience, the team reports the effects of a new synthetic compound that selectively blocks 11beta-HSD1 on the ability of mice to complete a memory task, called the Y maze.
Professor Jonathan Seckl from the University of Edinburgh, who discovered the role of 11beta-HSD1 in the brain, described the findings: “Normal old mice often have marked deficits in learning and memory just like some elderly people. We found that life-long partial deficiency of 11beta-HSD1 prevented memory decline with aging. But we were very surprised to find that the blocking compound works quickly over a few days to improve memory in old mice suggesting it might be a good treatment for the already elderly.”
The effects were seen after only 10 days of treatment.
Article Continues -> http://www.sciencedaily.com/releases/2010/10/101012173222.htm
Plants Kick-Started Evolutionary Drama of Earth''''s Oxygenation
A panser shark (predatory fish greater than 30 feet long) is a consequence of the Earth””s oxygenation event of 400 million years ago. (Credit: Staffan Waerndt / Swedish Museum of Natural History)
An international team of scientists, exploiting pioneering techniques at Arizona State University, has taken a significant step toward unlocking the secrets of oxygenation of the Earth””s oceans and atmosphere.
Evolution of the Earth””s multitude of organisms is intimately linked to the rise of oxygen in the oceans and atmosphere. The new research indicates that the appearance of large predatory fish as well as vascular plants approximately 400 million years ago coincided with an increase in oxygen, to levels comparable to those we experience today. If so, then animals from before that time appeared and evolved under markedly lower oxygen conditions than previously thought.
The researchers, including collaborators from Harvard, Denmark, Sweden and the United Kingdom, made use of a method developed at ASU by Ariel Anbar, a professor in the department of chemistry and biochemistry and the School of Earth and Space Exploration in the College of Liberal Arts and Sciences, and his research group. The method can be used to estimate global oxygen levels in ancient oceans from the chemical composition of ancient seafloor sediments.
Their important findings are presented in a paper published in the Proceedings of the National Academy of Sciences (PNAS), titled “Devonian rise in atmospheric oxygen correlated to radiations of terrestrial plants and large predatory fish.”
“There has been a lot of speculation over the years about whether or not oxygen in the atmosphere was steady or variable over the last 500 million years,” explained Anbar, who leads ASU””s Astrobiology Program. “This is the era during which animals and land plants emerged and flourished. So it””s a profound question in understanding the history of life. These new findings not only suggest that oxygen levels varied, but also that the variation had direct consequences for the evolution of complex life.”
The Earth is 4,500 million years old. Microbial life has probably thrived in the oceans for most of that time. However, until about 2,300 million years ago, the atmosphere contained only traces of oxygen. During that time, some microbes in the oceans likely produced oxygen as a byproduct of photosynthesis. But the quantities they produced were insufficient to accumulate much in the atmosphere and oceans. The situation changed with the “Great Oxidation Event,” 2,300 million years ago. Oxygen levels rose again around 550 million years ago. The first animals appear in the fossil record at this time, marking the beginning of an era that geologists call the “Phanerozoic” — a Greek word meaning “evident animals.” This new work explores how oxygen levels changed during the Phanerozoic.
Article Continues -> http://www.sciencedaily.com/releases/2010/10/101008121348.htm
How the Deaf Have Super Vision: Cat Study Points to Brain Reorganization
Using congenitally deaf cats and hearing cats, researchers showed that only two specific visual abilities are enhanced in the deaf: visual localization in the peripheral field and visual motion detection. (Credit: iStockphoto)
Deaf or blind people often report enhanced abilities in their remaining senses, but up until now, no one has explained how and why that could be. Researchers at The University of Western Ontario, led by Stephen Lomber of The Centre for Brain and Mind have discovered there is a causal link between enhanced visual abilities and reorganization of the part of the brain that usually handles auditory input in congenitally deaf cats.
The findings, published online in Nature Neuroscience, provide insight into the plasticity that may occur in the brains of deaf people.
Cats are the only animal besides humans that can be born deaf. Using congenitally deaf cats and hearing cats, Lomber and his team showed that only two specific visual abilities are enhanced in the deaf: visual localization in the peripheral field and visual motion detection. They found the part of the auditory cortex that would normally pick up peripheral sound enhanced peripheral vision, leading the researchers to conclude the function stays the same but switches from auditory to visual.
“The brain is very efficient, and doesn”t let unused space go to waste,” says Lomber, an associate professor in the Department of Physiology and Pharmacology at the Schulich School of Medicine & Dentistry, and Department of Psychology in the Faculty of Social Science. “The brain wants to compensate for the lost sense with enhancements that are beneficial. For example, if you”re deaf, you would benefit by seeing a car coming far off in your peripheral vision, because you can”t hear that car approaching from the side; the same with being able to more accurately detect how fast something is moving.”
Lomber and his team are trying to discover how a deaf brain differs from a hearing brain to better understand how the brain handles cochlear implants. If the brain has rewired itself to compensate for the loss of hearing, what happens when hearing is restored? “The analogy I use is, if you weren”t using your cottage and lent it to a friend. That friend gets comfortable, maybe rearranges the furniture, and settles in. They may not want to leave just because you”ve come back,” explains Lomber.
Article Continues -> http://www.sciencedaily.com/releases/2010/10/101010133604.htm
Butterflies Cure Themselves with Plants
Analysis by Jennifer Viegas
(Images: Jaap de Roode and Lisa Sharling)
Monarch butterflies can cure themselves and their offspring of disease by using medicinal plants, according to a new paper in the journal Ecology Letters.
The disease is caused by a protozoan parasite called Ophryocystis elektroscirrha. The parasite invades the gut of the caterpillars and then persists when the caterpillars become adult monarchs.
Project leader Jaap de Roode in eScience Commons today said, “We have shown that some species of milkweed, the larva’s food plants, can reduce parasite infection in the monarchs. And we have also found that infected female butterflies prefer to lay their eggs on plants that will make their offspring less sick, suggesting that monarchs have evolved the ability to medicate their offspring.”
De Roode, assistant professor of biology at Emory University, said, ““We believe that our experiments provide the best evidence to date that animals use medication.”
Jaap de Roode, who discusses his latest findings in this video
At Discovery News, we”ve touched on the topic before for other species. Spider monkeys, for example, are thought to have discovered a medicated body scratcher. But there are relatively few such studies on self-medication by animals.
In this case, there”s added interest because the behavior is enacted by a creature that, despite its beauty, is fairly low on the food chain. Plus, the behavior is trans-generational, says Thierry Lefevre, a post-doctoral fellow in de Roode’s lab. “While the mother is expressing the behavior, only her offspring benefit.”
Health-related decisions made by non-human species could also potentially benefit us in future. For example, researchers like chemical ecologist Mark Hunter have been studying milkweed plants to determine their medicinal properties.
