Cultural hitchhiking: How social behavior can affect genetic makeup in dolphins

A UNSW-led team of researchers studying bottlenose dolphins that use sponges as tools has shown that social behaviour can shape the genetic makeup of an animal population in the wild.Some of the dolphins in Shark Bay in Western Australia put conical marine sponges on their rostrums (beaks) when they forage on the sea floor — a non-genetic skill that calves apparently learn from their mother.Lead author, Dr Anna Kopps, says sponging dolphins end up with some genetic similarities because the calves also inherit DNA from their mothers. As well, it is likely that sponging dolphins are descendants of a “sponging Eve,” a female dolphin that first developed the innovation.”Our research shows that social learning should be considered as a possible factor that shapes the genetic structure of a wild animal population,” says Dr Kopps.”It is one of the first studies to show this effect — which is called cultural hitchhiking — in animals other than people.”The study is published in the journal Proceedings of the Royal Society B.Dr Kopps and her colleagues identified individual dolphins in western Shark Bay about 850 kilometres north of Perth. They observed them from a boat as they foraged for food, travelled around the bay, rested, and played with other dolphins.Genetic samples were also taken, and analysed for mitochondrial DNA type, which is only inherited from the mother.It was found that the dolphins that lived in shallow waters, where sponges do not grow, mainly fell into a genetic group called Haplotype H.The dolphins living in deep waters, where sponges do grow, were predominantly Haplotype E or Haplotype F.”This striking geographic distribution of a genetic sequence cannot be explained by chance,” says Dr Kopps, who carried out the research while at UNSW and is now at the University of Groningen.As well, the DNA results from 22 dolphins that both lived in deep water and used sponges as tools showed they were all Haplotype E.”For humans we have known for a long time that culture is an important factor in shaping our genetics. Now we have shown for the first time that a socially transmitted behaviour like tool use can also lead to different genetic characteristics within a single animal population, depending on which habitat they live in,” she says.The team includes UNSW’s Professor Bill Sherwin and researchers from the University of Zurich and Murdoch University.Story Source:The above story is based on materials provided by University of New South Wales. Note: Materials may be edited for content and length.

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Why do young people fail to find stable jobs and thrive?

Around the world, more and more young people are failing to find stable jobs and live independently. A new study from IIASA population researchers explains why.The numbers of young people who fail to transition from childhood to independent adulthood is growing — more and more young people find themselves without full-time jobs, relying on their parents, or staying longer in school. These changes can be traced changes in the global labor force and education according to a new study published today in the Finnish Yearbook of Population Research.”Young adults are doing increasingly worse economically, in spite of living in wealthy regions of the world,” says IIASA population expert Vegard Skirbekk. “At the same time, older adult age groups have been doing increasingly better.”Skirbekk, along with IIASA researchers Warren Sanderson and Marcin Stonawski conducted the study in order to examine the common factors that help young people transition to adulthood. They call the problem, “Young Adult Failure to Thrive Syndrome.”While the phenomenon had been recognized in individual countries, including Italy, France, Spain, and Japan, explanations have often focused on recent causes such as government fiscal difficulties. But the new study shows that failure to thrive can be traced to global economic and demographic shifts beginning in the 1980’s.The study finds that failure to thrive can be tied to three major economic factors worldwide. First, an increasingly globalized labor force means that workers can move more easily between countries. Second, education levels have soared around the world, meaning many more workers are available for skilled positions. Third, more women have joined the labor force. All these factors mean more competition for jobs, particularly for young people who have little practical experience.In addition to changes in labor supply, technological changes have both created and destroyed jobs, with a trend towards fewer industrial jobs and more service sector jobs.”These changes mean that even as economic conditions have improved for some in the population, young people are worse off today than they were 20 years ago,” says Sanderson.The researchers say that such economic disadvantages also have an effect on demographic questions such as fertility rates and family formation, as many young people cannot afford to start families until later in life.Story Source:The above story is based on materials provided by International Institute for Applied Systems Analysis. …

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Nine steps to save waterways and fisheries identified by researchers

The key to clean water and sustainable fisheries is to follow nine guiding principles of water management, says a team of Canadian biologists.Fish habitats need ecosystems that are rich in food with places to hide from predators and lay eggs, according to the framework published today in the journal Environmental Reviews.Humans have put key freshwater ecosystems at risk because of land development and the loss of the vegetation along rivers and streams, says John Richardson, a professor in the Dept. of Forest and Conservation Sciences at the University of British Columbia, one of 15 freshwater biologists who created the framework to help protect fish and ecosystems into the future.”Fish are strongly impacted when nutrients, sediments or pollutants are added to their habitat. We cannot protect fish without maintaining a healthy freshwater ecosystem,” says Richardson, who led the policy section on protecting fish habitats. Other policy sections addressed areas such as climate change and biodiversity.Connecting waterways are also critical for healthy ecosystems, says Richardson. “If fish can’t get to breeding or rearing areas because of dams, culverts, water intakes or other changes to their habitats, then the population will not survive,” he says.With more pressure on Canada’s freshwater ecosystems, Richardson and his colleagues wanted to create a framework of evidence-based principles that managers, policy makers and others could easily use in their work. “It’s a made in Canada solution, but the principles could be applied anywhere in the world,” he says.BACKGROUNDERHealthy freshwater ecosystems are shrinking and reports suggest that the animals that depend on them are becoming endangered or extinct at higher rates than marine or terrestrial species, says Richardson. Humans also depend on these ecosystems for basic resources like clean drinking water and food as well as economic activity from the natural resource sector, tourism and more.The components of a successful management plan include:Protect and restore habitats for fisheries Protect biodiversity as it enhances resilience and productivity Identify threats to ecosystem productivity Identify all contributions made by aquatic ecosystems Implement ecosystem based-management of natural resources while acknowledging the impact of humans Adopt a precautionary approach to management as we face uncertainty Embrace adaptive management — environments continue to change so research needs to be ongoing for scientific evidence-based decision making Define metrics that will indicate whether management plans are successful or failing Engage and consult with stakeholders Ensure that decision-makers have the capacity, legislation and authority to implement policies and management plans. These recommendations are based on nine principles of ecology:Acknowledge the physical and chemical limits of an ecosystem Population dynamics are at work and there needs to be a minimum number of fish for the population to survive Habitat quantity and quality are needed for fish productivity Connecting habitats is essential for movement of fish and their resources The success of freshwater species is influenced by the watershed Biodiversity enhances ecosystem resilience and productivity Global climate change affects local populations of fish Human impacts to the habitat affect future generations of fish Evolution is important to species survival Story Source:The above story is based on materials provided by University of British Columbia. Note: Materials may be edited for content and length.

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Molecular beacons light path to cardiac muscle repair

Sep. 5, 2013 — Pure cardiac muscle cells, ready to transplant into a patient affected by heart disease.That’s a goal for many cardiology researchers working with stem cells. Having a pure population of cardiac muscle cells is essential for avoiding tumor formation after transplantation, but has been technically challenging.Researchers at Emory and Georgia Tech have developed a method for purifying cardiac muscle cells from stem cell cultures using molecular beacons.Molecular beacons are tiny “instruments” that become fluorescent only when they find cells that have turned on certain genes. In this case, they target instructions to make a type of myosin, a protein found in cardiac muscle cells.Doctors could use purified cardiac muscle cells to heal damaged areas of the heart in patients affected by heart attack and heart failure. In addition, the molecular beacons technique could have broad applications across regenerative medicine, because it could be used with other types of cells produced from stem cell cultures, such as brain cells or insulin-producing islet cells.The results are published in the journal Circulation.”Often, we want to generate a particular cell population from stem cells for introduction into patients,” says co-senior author Young-sup Yoon, MD, PhD, professor of medicine (cardiology) and director of stem cell biology at Emory University School of Medicine. “But the desired cells often lack a readily accessible surface marker, or that marker is not specific enough, as is the case for cardiac muscle cells. This technique could allow us to purify almost any type of cell.”Gang Bao, PhD, whose laboratory has pioneered the design and use of molecular beacons, is co-senior author. Bao is Robert A. Milton chair, Wallace H. Coulter Department of Biomedical Engineering at Georgia Tech and Emory University. …

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More than one-third of populations worldwide may have low levels of vitamin D, study shows

Sep. 4, 2013 — A new systematic review published in the British Journal of Nutrition, is one of the first to focus on patterns of vitamin D status worldwide and in key population subgroups, using continuous values for 25(OH)D to improve comparisons.Share This:Principal investigator, Dr. Kristina Hoffmann of the Mannheim Institute of Public Health (MIPH), Medical Faculty Mannheim, Heidelberg University stated, “The strength of our study is that we used strict inclusion criteria to filter and compare data, using consistent values for 25(OH)D. Although we found a high degree of variability between reports of vitamin D status at the population level, more than one-third of the studies reviewed reported mean serum 25(OH)D values below 50 nmol/l.”Low levels of vitamin D have a potentially serious impact on health, particularly on bone and muscle health. In children, vitamin D deficiency is a cause of rickets; while in adults low values are associated with osteomalacia, osteopenia, osteoporosis and risk of fracture. Emerging evidence also points to increased risk for cancer and cardiovascular diseases. Yet despite its importance to public health, data about vitamin D status at the population level are limited and studies are hampered by lack of consensus and consistency.The study’s key findings include:37.3% of the studies reviewed reported mean serum 25(OH)D values below 50 nmol/l, values considered inadequate by health authorities worldwide. Only a limited number of studies for Latin America were available. Vitamin D values were higher in North America than in Europe or the Middle-East. Age-related differences were observed for the Asia-Pacific and Middle East regions, but not elsewhere. …

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Report proposes microbiology’s grand challenge to help feed the world

Aug. 27, 2013 — A greater focus on the role of microbiology in agriculture combined with new technologies can help mitigate potential food shortages associated with world population increases according to a new report from the American Academy of Microbiology.”Microbes are essential partners in all aspects of plant physiology, but human efforts to improve plant productivity have focused solely on the plant,” says Ian Sanders of University of Lausanne, chair of the colloquium that produced the report. “Optimizing the microbial communities that live in, on and around plants, can substantially reduce the need for chemical fertilizers, pesticides and herbicides.”The report, How Microbes can Help Feed the World, is based on the deliberation of a group of scientific experts who gathered for two days in Washington DC in December 2012 to consider a series of questions regarding how plant-microbe interactions could be employed to boost agricultural productivity in an environmentally and economically responsible way.It starts with a startling statistic: In order to feed the estimated global population of 9 billion in the year 2050, agricultural yields will have to increase by 70-100% .Improved understanding of plant-microbe interactions has the potential to increase crop productivity by 20% while reducing fertilizer and pesticide requirements by 20%, within 20 years, according to the report. These estimates rest on the recognition that all plants rely on microbial partners to secure nutrients, deter pathogens and resist environmental stress.The report looks in depth at the intimate relationship between microbes and agriculture including why plants need microbes, what types of microbes they need, how they interact and the scientific challenges posed by the current state of knowledge. It then makes a series of recommendations, including greater investment in research, the taking on of one or more grand challenges such as characterization of the complete microbiome of one important crop plant, and the establishment of a formal process for moving scientific discoveries from the lab to the field.”New technologies are making plant-microbe ecosystems easier to study and investment in this area of research could have dramatic benefits,” says Marilynn Roossinck, Pennsylvania State University, who helped organize the colloquium.Report: http://academy.asm.org/index.php/browse-all-reports/800-how-microbes-can-help-feed-the-world?utm_source=newsletter&utm_medium=email&utm_campaign=FeedTheWorld

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Genetic evidence shows recent population mixture in India

Aug. 8, 2013 — Scientists from Harvard Medical School and the CSIR-Centre for Cellular and Molecular Biology in Hyderabad, India, provide evidence that modern-day India is the result of recent population mixture among divergent demographic groups.The findings, published August 8 in the American Journal of Human Genetics, describe how India transformed from a country where mixture between different populations was rampant to one where endogamy — that is, marrying within the local community and a key attribute of the caste system — became the norm.”Only a few thousand years ago, the Indian population structure was vastly different from today,” said co-senior author David Reich, professor of genetics at Harvard Medical School. “The caste system has been around for a long time, but not forever.”In 2009, Reich and colleagues published a paper based on an analysis of 25 different Indian population groups. The paper described how all populations in India show evidence of a genetic mixture of two ancestral groups: Ancestral North Indians (ANI), who are related to Central Asians, Middle Easterners, Caucasians, and Europeans; and Ancestral South Indians (ASI), who are primarily from the subcontinent.However, the researchers wanted to glean clearer data as to when in history such admixture occurred. For this, the international research team broadened their study pool from 25 to 73 Indian groups.The researchers took advantage of the fact that the genomes of Indian people are a mosaic of chromosomal segments of ANI and ASI descent. Originally when the ANI and ASI populations mixed, these segments would have been extremely long, extending the entire lengths of chromosomes. However, after mixture these segments would have broken up at one or two places per chromosome, per generation, recombining the maternal and paternal genetic material that occurs during the production of egg and sperm.By measuring the lengths of the segments of ANI and ASI ancestry in Indian genomes, the authors were thus able to obtain precise estimates of the age of population mixture, which they infer varied about 1,900 to 4,200 years, depending on the population analyzed.While the findings show that no groups in India are free of such mixture, the researchers did identify a geographic element. “Groups in the north tend to have more recent dates and southern groups have older dates,” said co-first author Priya Moorjani, a graduate student in Reich’s lab at Harvard Medical School. “This is likely because the northern groups have multiple mixtures.””This genetic datatells us a three-part cultural and historical story,” said Reich, who is also an associate member of the Broad Institute. “Prior to about 4000 years ago there was no mixture. …

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Evolution on the inside track: How viruses in gut bacteria change over time

July 26, 2013 — Humans are far more than merely the sum total of all the cells that form the organs and tissues. The digestive tract is also home to a vast colony of bacteria of all varieties, as well as the myriad viruses that prey upon them. Because the types of bacteria carried inside the body vary from person to person, so does this viral population, known as the virome.By closely following and analyzing the virome of one individual over two-and-a-half years, researchers from the Perelman School of Medicine at the University of Pennsylvania, led by professor of Microbiology Frederic D. Bushman, Ph.D., have uncovered some important new insights on how a viral population can change and evolve — and why the virome of one person can vary so greatly from that of another. The evolution and variety of the virome can affect susceptibility and resistance to disease among individuals, along with variable effectiveness of drugs.Their work was published in the Proceedings of the National Academy of Sciences.Most of the virome consists of bacteriophages, viruses that infect bacteria rather than directly attacking their human hosts. However, the changes that bacteriophages wreak upon bacteria can also ultimately affect humans.”Bacterial viruses are predators on bacteria, so they mold their populations,” says Bushman. “Bacterial viruses also transport genes for toxins, virulence factors that modify the phenotype of their bacterial host.” In this way, an innocent, benign bacterium living inside the body can be transformed by an invading virus into a dangerous threat.At 16 time points over 884 days, Bushman and his team collected stool samples from a healthy male subject and extracted viral particles using several methods. They then isolated and analyzed DNA contigs (contiguous sequences) using ultra-deep genome sequencing .”We assembled raw sequence data to yield complete and partial genomes and analyzed how they changed over two and a half years,” Bushman explains. The result was the longest, most extensive picture of the workings of the human virome yet obtained.The researchers found that while approximately 80 percent of the viral types identified remained mostly unchanged over the course of the study, certain viral species changed so substantially over time that, as Bushman notes, “You could say we observed speciation events.”This was particularly true in the Microviridae group, which are bacteriophages with single-stranded circular DNA genomes. Several genetic mechanisms drove the changes, including substitution of base chemicals; diversity-generating retroelements, in which reverse transcriptase enzymes introduce mutations into the genome; and CRISPRs (Clustered Regularly Interspaced Short Palindromic Repeats), in which pieces of the DNA sequences of bacteriophages are incorporated as spacers in the genomes of bacteria.Such rapid evolution of the virome was perhaps the most surprising finding for the research team. …

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Gene mutation linked to obesity: Mice gain weight even when fed normal amounts of food

July 18, 2013 — Researchers at Boston Children’s Hospital have identified a genetic cause of severe obesity that, though rare, raises new questions about weight gain and energy use in the general obese population. The research, published in the journal Science on July 19, involved genetic surveys of several groups of obese humans and experiments in mice.Mice with the genetic mutation gained weight even while eating the same amount of food as their normal counterparts; the affected gene, Mrap2, has a human counterpart (MRAP2) and appears to be involved in regulating metabolism and food consumption.”These mice aren’t burning the fat, they’re somehow holding onto it,” says the study’s lead investigator Joseph Majzoub, MD, chief of endocrinology at Boston Children’s. “Mice with the genetic mutation gained more weight, and we found similar mutations in a cohort of obese humans.”The protein created by the Mrap2 gene appears to facilitate signaling to a receptor in the brain called Mc4r, which helps increase metabolism and decrease appetite as part of a larger signaling chain involved in energy regulation. Fat cells produce the hormone leptin, prompting receptors in the brain to instigate production of a second hormone, αMSH. Mc4r detects this hormone with the aid of Mrap2, leading to a decrease in appetite and weight. Mutations in this signaling chain, including mutations in Mc4r, are known to increase the likelihood of obesity.Majzoub, first author Masato Asai, MD, PhD, now at Nagoya University in Japan, and colleagues studied mice with the Mrap2 gene knocked out both overall and just in the brain. In both cases, the mice grew to about twice their normal size. Weight gain was greatest when both copies of Mrap2 were knocked out, but the mice still showed weight gain and appetite increase with one working copy of the gene. The weight gain was more pronounced in males than females. In addition, the mice without Mrap2 had more exaggerated weight gain when fed a high-fat diet than normal mice.Surprisingly, while the mice without Mrap2 didn’t eat more at first, they still gained weight faster than the controls. …

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DNA flaws may contribute to cancer risk in people with type 2 diabetes

July 14, 2013 — A type of genetic abnormality linked to cancer is more common in people with type 2 diabetes than the rest of the population, a new study has found.People with type 2 diabetes are already known to have a higher risk of cancers, especially blood cancers like lymphoma and leukaemia. The new study, led by scientists at Imperial College London and CNRS in France, suggests that mutations called clonal mosaic events (CMEs) may partly explain why this is.CMEs are defects that result in some cells having extra copies or missing copies of large chunks of DNA. They are very rare in young people but more common as we get older. Among those aged over 70, around one in 50 people have some of these mutations. Research published last year found that people with CMEs have a 10-fold higher risk of blood cancers.In the new study, published in Nature Genetics, researchers looked for CMEs in blood samples from 7,437 participants in genetic studies in Europe, including 2,208 people with type 2 diabetes. They found that CMEs were four times more common in people with type 2 diabetes.“Type 2 diabetes is a disease that accelerates ageing, so we wondered if it would make people more likely to have these genetic defects that are associated with ageing,” said Professor Philippe Froguel, from the School of Public Health at Imperial College London, who led the study.“This finding may partly explain why people with type 2 diabetes are more likely to get blood cancers. It could have profound clinical implications. It may be useful for doctors to test for CMEs in patients with type 2 diabetes to identify those who have the highest risk of cancers. These patients would be followed up closely to watch for early signs of leukaemia and could start having mild chemotherapy.”They also found that diabetes patients with CMEs had a much higher rate of complications such as kidney failure, eye disease or heart disease.The study was supported by the Contrat de Projets Etat–Région Nord-Pas-De-Calais, the Délégation Régionale à la Recherche et à la Technologie de la Région Nord-Pas-De-Calais, the European Union and the Centre National de la Recherche Scientifique (CNRS).

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Vaccinated children: A powerful protection for older adults

July 10, 2013 — Children who receive a vaccine to prevent blood and ear infections, appear to be reducing the spread of pneumonia to the rest of the population, especially their grandparents and other older adults. Results of a new Vanderbilt study, funded by the Centers for Disease Control and Prevention (CDC), and published in the July 11 issue of the New England Journal of Medicine show infant vaccination against pneumococcal bacteria since 2000 has reduced pneumonia hospitalization by more than 10 percent across the board, with the most significant reductions at the extreme ends of the age spectrum.”Pneumonia is a leading cause of hospitalization in the United States. The protective effect we saw in older adults, who do not receive the vaccine but benefit from vaccination of infants, is quite remarkable. It is one of the most dramatic examples of indirect protection or herd immunity we have seen in recent years,” said the study’s first author, Marie Griffin, M.D., MPH, professor of Preventive Medicine and Medicine.James Powers, M.D., associate professor of Medicine in Geriatrics, said the study suggests this herd immunity is an even more effective prevention for elders than the vaccine currently recommended to prevent pneumonia in older adults.”The reduction in pneumonia hospitalizations among older adults appears to be related to long-term effects following introduction of PCV7 immunization for children. We have not seen a similar response to the pneumovax 23 vaccine (recommended for older adults) introduced in 1983,” Powers said.Griffin, along with co-author Carlos Grijalva, M.D., MPH, assistant professor of Preventive Medicine, and their colleagues, examined a large national database for hospitalization from pneumonia from 1997 through 2009. The result is a long-term snapshot of how pneumococcal conjugate vaccine (PCV7 or Prevnar) has impacted pneumonia rates since it was added to the childhood vaccine list in 2000.Results show children under age 2 experienced a 40 percent reduction in pneumonia hospitalizations. Reduction in hospitalizations of older children and adults — who did not receive the vaccine — while less dramatic, was still impressive. But researchers said what began as a slow decline in 2000 in the rate of pneumonia hospitalizations for adults over the age of 65, appeared to accelerate over the last decade. By 2009, more than half the nationwide decline in pneumonia hospitalizations could be attributed to older adults, with some 70,000 fewer annual hospitalizations for those age 85 and older.”Humans are the only reservoir for the pneumococcus. This group of bacteria can live in the nose and throat of healthy people, especially children. …

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Language intervention levels playing field for English language learners

June 25, 2013 — A new approach to teaching pre-kindergarten could take a bite out of the achievement gap and level the playing field for America’s growing population of English language learners, according to a recently published study by researchers at Vanderbilt’s Peabody College of education and human development.”We are excited that we have helped teachers develop ways of teaching that result in such remarkable gains among children,” David K. Dickinson, professor of education and one of the project’s leaders, said. “Our teachers are committed to continuing using the approaches that are working, which means that many more children will benefit from being in their classrooms.”The Enhanced Language and Literacy Success Project, a four-year intervention and research effort performed in collaboration with Metropolitan Nashville Public Schools, proved that a language-rich pre-K curriculum paired with coaching, feedback and professional development for teachers, can improve student outcomes significantly.An article about the research was recently published by the journal Early Childhood Research Quarterly.”Research shows that children from low income families are behind when they start kindergarten and it’s really difficult for them to catch up,” said Sandra Jo Wilson, associate director of the Peabody Research Institute.Wilson, one of the project leaders, managed the analysis of data for the study.”Our study demonstrates that it is possible for children from diverse languages and backgrounds to enter kindergarten with literacy skills at or near national norms,” she said.The researchers evaluated the outcomes of 700 students and 13 teachers in seven Nashville pre-K programs. About half of the students were English language learners and nearly all came from low-income households.”The element of providing feedback to teachers turned out to be a key to the curriculum’s success,” Dickinson said. Dickinson co-authored the curriculum, helped guide the delivery of the intervention and did some of the teacher professional development. “Teachers were asking for their reports and wanted to see how they were doing — they were very responsive to what the coaches had to say.”Deborah Wells Rowe, associate professor of education at Peabody and an expert on early childhood writing, worked with the teachers to incorporate writing into their lessons.The Enhanced Language and Literacy Success Project is supported by U.S. Department of Education grant No. S359B080078.

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Cities are a new kind of complex system: Part social reactor, part network

June 20, 2013 — Cities have long been likened to organisms, ant colonies, and river networks. But these and other analogies fail to capture the essence of how cities really function.New research by Santa Fe Institute Professor Luis Bettencourt suggests a city is something new in nature — a sort of social reactor that is part star and part network, he says.”It’s an entirely new kind of complex system that we humans have created,” he says. “We have intuitively invented the best way to create vast social networks embedded in space and time, and keep them growing and evolving without having to stop. When that is possible, a social species can sustain ways of being incredibly inventive and productive.”In a paper published this week in Science, Bettencourt derives a series of mathematical formulas that describe how cities’ properties vary in relation to their population size, and then posits a novel unified, quantitative framework for understanding how cities function and grow.His resulting theoretical framework predicts very closely dozens of statistical relationships observed in thousands of real cities around the world for which reliable data are available.”As more people lead urban lives and the number and size of cities expand everywhere, understanding more quantitatively how cities function is increasingly important,” Bettencourt says. “Only with a much better understanding of what cities are will we be able to seize the opportunities that cities create and try to avoid some of the immense problems they present. This framework is a step toward a better grasp of the functioning of cities everywhere.”What has made this new view of cities possible is the growing opportunities in recent years to collect and share data on many aspects of urban life. With so much new data, says Bettencourt, it’s easier than ever to study the basic properties of cities in terms of general statistical patterns of such variables as land use, urban infrastructure, and rates of socioeconomic activity.For more than a decade, Bettencourt and members of SFI’s Cities & Urbanization research team have used this data to painstakingly lay the foundation for a quantitative theory of cities. Its bricks and mortar are the statistical “scaling” relationships that seem to predict, based on a city’s size, the average numerical characteristics of a city, from the number of patents it produces to the total length of its roads or the number of social interactions its inhabitants enjoy.Those relationships and the related equations, models, network analyses, and methods provide the basis for Bettencourt’s theoretical framework.So what is a city? Bettencourt thinks the only metaphor that comes close to capturing a city’s function is from stellar physics: “A city is first and foremost a social reactor,” Bettencourt explains. “It works like a star, attracting people and accelerating social interaction and social outputs in a way that is analogous to how stars compress matter and burn brighter and faster the bigger they are.”This, too, is an analogy though, because the math of cities is very different from that of stars, he says.Cities are also massive social networks, made not so much of people but more precisely of their contacts and interactions. …

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Oysters could rebound more quickly with limited fishing and improved habitat

June 13, 2013 — A new study shows that combining improved oyster restoration methods with limits on fishing in the upper Chesapeake could bring the oyster population back to the Bay in a much shorter period of time. The study led by Michael Wilberg of the University of Maryland Center for Environmental Science’s Chesapeake Biological Laboratory assessed a range of management and restoration options to see which ones would have the most likelihood success.”This new model we developed suggests that oysters should be able to come back if we help them out by reducing fishing pressure and improving their habitat,” said Wilberg.Eastern oysters in the Chesapeake Bay have undergone a drastic decrease in abundance over the past century due to overfishing and disease. The population is currently estimated to be less than one percent of its historic high, making substantial restoration efforts necessary if the population is to recover.The team’s study shows that if oysters were allowed to reproduce naturally and fishing were halted, it would take between 50 to 100 years for oyster abundance to reach as high a level as could be supported by the Bay. If fishing were reduced to about half its current level, it would take as many as 200 to 500 years to see a healthy population restored to the Bay.”The fishery as it has been practiced hasn’t been sustainable, and our model helps explain why,” said Wilberg. “Oysters just can’t replace the shell that has been removed fast enough to keep up.”Oysters are called ecosystem engineers because they build habitat for themselves and other creatures. Oyster harvesting methods, such as dredging and tonging, chip away at the oyster reef and knock it down, spreading the shells over the bottom and making the remaining oysters prone to being covered by silt or moving them to a soft surface where oysters cannot grow.Since reefs are the place where oysters are born and reproduce, fishing not only removes adults from the population, but also removes habitat essential to their survival.”Oysters should be able to rebuild their reefs if we leave them alone,” said Wilberg. “It’s an experiment that hasn’t been tried yet.”

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Difference in arterial health seen in highly active college-age people compared to inactive peers

May 31, 2013 — Indiana University researchers found that people in their 20s already began to demonstrate arterial stiffening — when arteries become less compliant as blood pumps through the body — but their highly active peers did not.The researchers made a similar discovery with middle-age men and women, finding that highly active study participants did not show the arterial stiffening that typically comes with aging, regardless of their gender or age. A reduction in compliance of the body’s arteries is considered a risk factor, predictive of future cardiovascular disease, such as high blood pressure and stroke. This new study is the first to examine arterial stiffening in a young, healthy population.”It was surprising,” said Joel Stager, professor in the Department of Kinesiology in the IU School of Public Health-Bloomington. “The college-age group, which reflected the general population, already showed a difference in the health of their small arteries. Compliance of the small arteries, in particular, is seen as an effective predictor of future cardiovascular disease.”The researchers looked at compliance of large and small arteries. For the middle-aged study participants, typical stiffening was seen in both types of arteries for those who were inactive and moderately active, but not for the highly active. In the younger groups, the stiffening was seen only in the smaller arteries for the less active group.”This indicates that the effect of exercise reported for aging populations seems to exist in young populations as well,” the researchers wrote in their report. “That small artery compliance is low in the less active young population should be of general concern, as low small arterial compliance is recognized as an index of cardiovascular risk.”Findings from “Arterial Compliance in a Young Population” were discussed during a poster presentation at the annual meeting of the American College of Sports Medicine in Indianapolis on May 28 to June 1. Co-authors are Christopher Mattson, Maleah Holland and Eric Ress, researchers at the IU School of Public Health-Bloomington. Findings from “Small and Large Arterial Stiffness and Aging in Highly Active People” also were discussed during a poster presentation on Wednesday. …

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Decoding the genome of the camel

May 28, 2013 — By sequencing the genome of a Bactrian camel, researchers at the Vetmeduni Vienna have made a significant contribution to population genetic research on camels. The study has laid the foundation for future scientific work on these enigmatic desert animals. A blood sample from a single Bactrian camel with the evocative name of “Mozart” provided the genetic raw material for the work, which was undertaken by Pamela Burger at the Institute of Population Genetics.

Camels are divided into two species, the one-humped dromedary and the two-humped Bactrian camel. Whether equipped with one or two humps, camels are precious in desert regions throughout the world. Their ability to carry heavy loads over long distances makes them ideally suited for transportation. In addition, camels are able to survive for weeks in hostile environments without food and water. Despite the extremely arid conditions, camels still provide enough milk for human consumption and also have an important role as a source of meat. Camels are specialists when it comes to adapting to the environment and have been characterized as sustainable food producers.

Focusing on camel domestication

Pamela Burger heads one of the few research groups in Europe that study camel genetics. Burger and her colleagues are primarily interested in the domestication of camels, which took place around 3,000 to 6,000 years ago. Genetic data provide important clues on the breeding strategies and selection processes that were applied by humans at that time. The DNA code also represents a rich resource for addressing questions on phylogenetic relationships between animals. Burger is one of the first scientists to sequence large parts of the genome of a Bactrian camel and make it available to the public.

Milestone in camel genetics

Until recently, the genetic code of the Camel had not been fully analysed. Genetic research on these animals was therefore difficult or even impossible. In contrast, the entire genetic information of the human genome was available as long ago as 2003 and the genetic code of various animals and plants is publicly available, giving researchers access to an enormous set of data. To date, the lack of basic genetic data has severely hampered studies of camel genetics. Pamela Burger and her team are pioneers in presenting this essential dataset.

Relationship among the one- and the two-humped

The scientists were able to find 116,000 so-called SNPs (single nucleotide polymorphisms) in the genetic sequence of the Bactrian camel. SNPs are single base-pair changes within a DNA strand that provide the basis for studying relationships among species and between single animals. The genetic relationship between the Bactrian camel (Camelus bactrianus) and the dromedary (Camelus dromedarius) is close. 85 per cent of the genomic sequences expressed in the dromedary can be found in the Bactrian camel. Burger explains, “Mozart’s genome provides us with the basis for further comparative research on other camelids such as dromedary, lama and alpaca.”

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New plant protein discoveries could ease global food and fuel demands

May 1, 2013 — New discoveries of the way plants transport important substances across their biological membranes to resist toxic metals and pests, increase salt and drought tolerance, control water loss and store sugar can have profound implications for increasing the supply of food and energy for our rapidly growing global population.

That’s the conclusion of 12 leading plant biologists from around the world whose laboratories recently discovered important properties of plant transport proteins that, collectively, could have a profound impact on global agriculture. They report in the May 2nd issue of the journal Nature that the application of their findings could help the world meet its increasing demand for food and fuel as the global population grows from seven billion people to an estimated nine billion by 2050.

“These membrane transporters are a class of specialized proteins that plants use to take up nutrients from the soil, transport sugar and resist toxic substances like salt and aluminum,” said Julian Schroeder, a professor of biology at UC San Diego who brought together 11 other scientists from Australia, Japan, Mexico, Taiwan, the U.S. and the U.K. to collaborate on a paper describing how their discoveries collectively could be used to enhance sustainable food and fuel production.

Schroeder, who is also co-director of a new research entity at UC San Diego called Food and Fuel for the 21st Century, which is designed to apply basic research on plants to sustainable food and biofuel production, said many of the recent discoveries in his and other laboratories around the world had previously been “under the radar” — known only to a small group of plant biologists — but that by disseminating these findings widely, the biologists hoped to educate policy makers and speed the eventual application of their discoveries to global agriculture.

“Of the present global population of seven billion people, almost one billion are undernourished and lack sufficient protein and carbohydrates in their diets,” the biologists write in their paper. “An additional billion people are malnourished because their diets lack required micronutrients such as iron, zinc and vitamin A. These dietary deficiencies have an enormous negative impact on global health resulting in increased susceptibility to infection and diseases, as well as increasing the risk of significant mental impairment. During the next four decades, an expected additional two billion humans will require nutritious food. Along with growing urbanization, increased demand for protein in developing countries coupled with impending climate change and population growth will impose further pressures on agricultural production.”

“Simply increasing inorganic fertilizer use and water supply or applying organic farming systems to agriculture will be unable to satisfy the joint requirements of increased yield and environmental sustainability,” the scientists added. “Increasing food production on limited land resources will rely on innovative agronomic practices coupled to the genetic improvement of crops.”

One of Schroeder’s research advances led to the discovery of a sodium transporter that plays a key role in protecting plants from salt stress, which causes major crop losses in irrigated fields, such as those in the California central valley. Agricultural scientists in Australia, headed by co-author Rana Munns and her colleagues, have now utilized this type of sodium transporter in breeding research to engineer wheat plants that are more tolerant to salt in the soil, boosting wheat yields by a whopping 25 percent in field trials. This recent development could be used to improve the salt tolerance of crops, so they can be grown on previously productive farmland with soil that now lies fallow.

Another recent discovery, headed by co-authors Emanuel Delhaize in Australia and Leon Kochian at Cornell University, opens up the potential to grow crops on the 30 percent of Earth’s acidic soils that are now unusable for agricultural production, but that otherwise could be ideal for agriculture.

“When soils are acidic, aluminum ions are freed in the soil, resulting in toxicity to the plant,” the scientists write. “Once in the soil solution, aluminum damages the root tips of susceptible plants and inhibits root growth, which impairs the uptake of water and nutrients.”

From their recent findings, the plant biologists now understand how transport proteins control processes that allow roots to tolerate toxic aluminum. By engineering crops to convert aluminum ions into a non-toxic form, they said, agricultural scientists can now turn these unusable or low-yielding acidic soils into astonishingly productive farmland to grow crops for food and biofuels.

Other recent transport protein developments described by the biologists have been shown to increase the storage of iron and zinc in food crops to improve their nutritive qualities. “Over two billion people suffer from iron and zinc deficiencies because their plant-based diets are not a sufficiently rich source of these essential elements,” the biologists write.

The scientists also discovered transporters in plants and symbiotic soil fungi that allow crops to acquire phosphate — an element essential for plant growth and crop yield — more efficiently and to increase the uptake of nitrogen fertilizers, which are costly to produce. “Nitrogen fertilizer production consumes one percent of global energy usage and poses the highest input cost for many crops,” the scientists write. “Nevertheless, only 20 to 30 of the phosphate and 30 to 50 percent of the nitrogen fertilizer applied are utilized by plants. The remainder can lead to production of the greenhouse gas nitrous oxide, or to eutrophication of aquatic ecosystems through water run-off.”

The biologists said crops could be made more efficient in using water through discoveries in plant transport proteins that regulate the “stomatal pores” in the epidermis of leaves, where plants lose more than 90 percent of their water through transpiration. Two other major goals in agriculture are increasing the carbohydrate content and pest-resistance of crops. A recent discovery of protein transporters that move sugar throughout the plant has been used to develop rice plants that confer pest resistance to crops, the biologists said, providing a novel way to simplify the engineering of crops with high yields and pest resistance, which could lead to reduced use of pesticides in the field.

“Just as our cell phones will need more advanced technology to carry more information, plants need better or new transporters to make them work harder on existing agricultural land,” said Dale Sanders, director of the John Innes Centre in the U.K. and a corresponding co-author of the paper. “Synthetic fertilizers and pesticides are the current solution, but we can make plants better at finding and carrying their own chemical elements.”

These recent developments in understanding the biology of plant transporters are leading to improved varieties less susceptible to adverse environments and for improving human health. Says Schroeder, “More fundamental knowledge and basic discovery research is needed and would enable us to further and fully exploit these advances and pursue new promising avenues of plant improvement in light of food and energy demands and the need for sustainable yield gains.”

In addition to Schroeder and Sanders, the co-authors of the paper are Emmanuel Delhaize of CSIRO in Canberra, Australia; Wolf Frommer of the Carnegie Institution of Science; Mary Lou Guerinot of Dartmouth College; Maria Harrison of the Boyce Thompson Institute for Plant Research in Ithaca, NY; Luis Herrera-Estrella of the Center for Research and Advanced Studies of the National Polytechnic Institute in Iraputo, Mexico; Tomoaki Horie of Shinshu University in Nagano, Japan; Leon Kochian of Cornell University; Rana Munns of the University of Western Australia in Perth; Naoko Nishizawa of Ishikawa Prefectural University in Japan; and Yi-Fang Tsay of the National Academy of Science of Taiwan.

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