XENO-NUCLEIC ACIDS – alternatives to DNA / RNA

Genetic information storage and processing rely on just two polymers, DNA and RNA, yet whether their role reflects evolutionary history or fundamental functional constraints is currently unknown. With the use of polymerase evolution and design, a Group of Scientists have shown that genetic information can be stored in and recovered from six alternative genetic polymers based on simple nucleic acid architectures not found in nature [xeno-nucleic acids (XNAs)]. They also select XNA aptamers, which bind their targets with high affinity and specificity, demonstrating that beyond heredity, specific XNAs have the capacity for Darwinian evolution and folding into defined structures. Thus, heredity and evolution,

CENSORSHIP OF SCIENTIFIC ARTICLE CREATES CONTROVERSY

Scientists have created an H5N1 avian influenza strain that has been genetically altered and is now easily transmissible between ferrets, the animals that most closely mimic the human response to flu. Flu researchers believe it's likely that the pathogen, if it emerged in nature or were released, would trigger an influenza pandemic, quite possibly with many millions of deaths. The virus's creators say the research, which has been submitted for publication, promises major public health benefits. Knowing exactly what makes H5N1 a virus with pandemic potential is useful because scientists can look out for such

Global warming ended ice age on earth

Rising levels of carbon dioxide really did bring about the end of the most recent ice age, say researchers. By compiling a global climate record, a team has shown that regions in which concentrations of greenhouse gases increased after the warming were exceptions to the big picture. There are many ideas about what caused the end of the last ice age 10,000 years ago, but a lack of data has hindered testing of hypotheses. It has been known that changes in temperature and CO2 levels were closely correlated during this time, but no one has been able to prove that CO2 caused the warming. Atmospheric CO2 levels increased by around 100 parts per

Genome analysis reveals malarial genomic region responsible for drug resistance

Researchers have identified a region of the malaria-parasite genome that underlies resistance to the most effective current treatment. The finding comes as drug resistance seems to be spreading in Southeast Asia.
Artemisinin has become the go-to treatment nearly everywhere that malaria is endemic. Resistance to it was first identified in 2005 in western Cambodia. Resistance does not necessarily cause artemisinin treatment to fail completely, but it does slow the clearance of the malaria-causing parasite Plasmodium falciparum from patients' blood.
To find the causes of artemisinin resistance, Ian Cheeseman, a geneticist at the Texas Biomedical Research Institute in San Antonio, and his colleagues compared Cambodian, Thai and Laotian P. falciparumpopulations that had differing clearance rates after artemisinin treatment. Their results are published inScience today1.Researchers are concerned that artemisinin-resistant strains of P. falciparum

Two Human Ancestor Species Co-Existed

A fossil discovered in Ethiopia suggests that humans' prehistoric relatives may have lived in the trees for a million years longer than was previously thought.
The find may be our first glimpse of a separate, extinct, branch of the human family, collectively called hominins. It also hints that there may have been several evolutionary paths leading to feet adapted for walking upright.
The fossil, a partial foot, was found in 3.4-million-year-old rocks at Woranso-Mille in the Afar region of Ethiopia. Bones of the hominin Australopithecus afarensis — the species to which the famous 'Lucy' skeleton belongs — have also been found in this location and from the same period.

Au. afarensis has a big toe that is more closely aligned with the other digits on the foot, an adaptation that provides support during upright walking. Au. afarensis “was fully bipedal and had already abandoned life in the trees”, says study author Yohannes Haile-Selassie of the Cleveland Museum of Natural History in Ohio, whereas the newly discovered creature had not seemingly committed to life on the ground.But unlike Au. afarensis, the latest find has an opposable big toe — rather like a thumb
 on the foot — that would have allowed the species to grasp branches while climbing. Modern apes have similar toes, but the youngest hominin previously known to have them is Ardipithecus ramidus, which lived about 4.4 million years ago. The details of the discovery are published today in Nature1.
Other features of the fossil foot show that it did not belong to an ape, but that it is truly a member of the hominins, says Haile-Selassie. The latest specimen is “very much like the Ardipithecus foot, which I believe had many hominin features, so it’s likely to be a hominin”, agrees Daniel Lieberman, an anthropologist at Harvard University in Cambridge, Massachusetts, who was not involved in the study.
Good grasp of history
The discovery shows that one hominin lineage had grasping feet for at least a million years after Ar. ramidus. The creature was probably more agile in the trees than Au. afarensis but less nimble on two feet, says William Harcourt-Smith, an anthropologist at the City University of New York’s Lehman College. “We can only get a tantalizing glimpse at this, but its bipedal gait is likely to have been very different from Lucy’s and was probably a lot less efficient,” he says.
The finding will force a rethink regarding the course of early hominin evolution, Harcourt-Smith adds. The addition of a mystery hominin species at this crucial time period suggests that the new species' lineage split from that leading to Lucy earlier in hominin history, and provides further evidence against the idea that modern humans evolved via a linear progression of species from apes. “This [finding] is fascinating, and makes the evolution of this defining behaviour not a single, linear evolutionary event, but a far more complex affair,” Harcourt-Smith says.

Link to Nature Paper  

doi:10.1038/nature.2012.10342

 

The Burtele partial foot (BRT-VP-2/73). A laboratory photo after cleaning and preparation. It is shown here in its anatomically articulated form.
© The Cleveland Museum of Natural History