With the discovery of Mimivirus ten years ago and, more recently, Megavirus chilensis , researchers thought they had reached the farthest corners of the viral world in terms of size and genetic complexity. With a diameter in the region of a micrometer and a genome incorporating more than 1,100 genes, these giant viruses, which infect amoebas of the Acanthamoeba genus, had already largely encroached on areas previously thought to be the exclusive domain of bacteria.
For the sake of comparison, common viruses such as the influenza or AIDS viruses, only contain around ten genes each.In the article published in Science, the researchers announced they had discovered two new giant viruses: •Pandoravirus salinus, on the coast of Chile;•Pandoravirus dulcis, in a freshwater pond in Melbourne, Australia.Detailed analysis has shown that these first two Pandoraviruses have virtually nothing in common with previously characterized giant viruses. What's more, only a very small percentage (6%) of proteins encoded by Pandoravirus salinus are similar to those already identified in other viruses or cellular organisms. With a genome of this size, Pandoravirus salinus has just demonstrated that viruses can be more complex than some eukaryotic cells . Another unusual feature of Pandoraviruses is that they have no gene allowing them to build a protein like the capsid protein, which is the basic building block of traditional viruses.
Despite all these novel properties, Pandoraviruses display the essential characteristics of other viruses in that they contain no ribosome, produce no energy and do not divide.This groundbreaking research included an analysis of the Pandoravirus salinus proteome, which proved that the proteins making it up are consistent with those predicted by the virus’ genome sequence. Pandoraviruses thus use the universal genetic code shared by all living organisms on the planet. This shows just how much more there is to learn regarding microscopic biodiversity as soon as new environments are considered. The simultaneous discovery of two specimens of this new virus family in sediments located 15,000 km apart indicates that Pandoraviruses, which were completely unknown until now, are very likely not rare. It definitively bridges the gap between viruses and cells – a gap that was proclaimed as dogma at the very outset of modern virology back in the 1950s. It also suggests that cell life could have emerged with a far greater variety of pre-cellular forms than those conventionally considered, as the new giant virus has almost no equivalent among the three recognized domains of cellular life, namely eukaryota (or eukaryotes), eubacteria, and archaea.
The famed psychologist explains why one is not the other though they are often confused.
1. Individualize your teaching as much as possible. Instead of “one size fits all,” learn as much as you can about each student, and teach each person in ways that they find comfortable and learn effectively. Of course this is easier to accomplish with smaller classes. But ‘apps’ make it possible to individualize for everyone.
Middle schoolers soak up marine biology while aboard ship (video) Victoria Advocate A $25,000 Alcoa Foundation grant also funds a High School Robotics Program, Travis Middle School Water Watchers, Texas Scholars and new equipment to enhance campus...
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Researchers recently announced the successful use of a new type of antibacterial agent called a PPMO, which appears to function as well or better than an antibiotic, but may be more precise and also solve problems with antibiotic resistance.
"The mechanism that PPMOs use to kill bacteria is revolutionary," said Bruce Geller, a professor of microbiology in the OSU College of Science and lead author on the study. "They can be synthesized to target almost any gene, and in that way avoid the development of antibiotic resistance and the negative impacts sometimes associated with broad-spectrum antibiotics. "Molecular medicine," Geller said, "is the way of the future."
PPMO stands for a peptide-conjugated phosphorodiamidate morpholino oligomer -- a synthetic analog of DNA or RNA that has the ability to silence the expression of specific genes. Compared to conventional antibiotics, which are often found in nature, PPMOs are completely synthesized in the laboratory with a specific genetic target in mind.
In animal laboratory tests against A. baumannii, one of the most dangerous Acinetobacter strains, PPMOs were far more powerful than some conventional antibiotics like ampicillin, and comparable to the strongest antibiotics available today. They were also effective in cases where the bacteria were resistant to antibiotics.
PPMOs have not yet been tested in humans. However, their basic chemical structure, the PMO, has been extensively tested in humans and found safe. Although the addition of the peptide to the PPMO poses an uncertain risk of toxicity, the potency of PPMOs reduces the risk while greatly improving delivery of the PMOs into bacterial cells, Geller said.
Geller said research is being done with Acinetobacter in part because this pathogen has become a huge global problem, and is often spread in hospitals. It can cause respiratory infection, sepsis, and is a special concern to anyone whose immune system is compromised. Wounds in military battle conditions have led to numerous cases in veterans, and A. baumannii is now resistant to many antibiotics. "Urgent new approaches to therapeutics are needed," the scientists said in their report.
Scientists are investigating this rare evolutionary trait, thought to have evolved to improve offspring's chances of survival Just like humans, killer whales experience menopause – and the rare evolutionary trait improves their offspring's chances...
Advoctes of MOOCs claim they have the potential to transform higher education by expanding academic access.But it remains to be seen whether this promise can be realized. We asked the WSJ Experts to weigh in.
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