Partial structure of the phylloxin gene from the giant monkey frog, Phyllomedusa bicolor: parallel cloning of precursor cDNA and genomic DNA from lyophilized skin secretion.

Phylloxin is a novel prototype antimicrobial peptide from the skin of Phyllomedusa bicolor. Here, we describe parallel identification and sequencing of phylloxin precursor transcript (mRNA) and partial gene structure (genomic DNA) from the same sample of lyophilized skin secretion using our recently-described cloning technique. The open-reading frame of the phylloxin precursor was identical in nucleotide sequence to that previously reported and alignment with the nucleotide sequence derived from genomic DNA indicated the presence of a 175 bp intron located in a near identical position to that found in the dermaseptins. The highly-conserved structural organization of skin secretion peptide genes in P. bicolor can thus be extended to include that encoding phylloxin (plx). These data further reinforce our assertion that application of the described methodology can provide robust genomic/transcriptomic/peptidomic data without the need for specimen sacrifice.

Aug. 27, 2010 — Kissing a frog won't turn it into a prince -- except in fairy tales -- but frogs may be hopping toward a real-world transformation into princely allies in humanity's battle with antibiotic-resistant infections that threaten millions of people worldwide. Scientists have reported that frog skin contains natural substances that could be the basis for a powerful new genre of antibiotics.
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In a report at the 240th National Meeting of the American Chemical Society on August 26, the team of stalwart frog-fanciers described enlisting colleagues worldwide to ship secretions from hundreds of promising frog skins to their laboratory in the United Arab Emirates. Using that amphibious treasure trove, they identified more than 100 antibiotic substances in the skins of different frog species from around the world. One even fights "Iraqibacter," the bacterium responsible for drug-resistant infections in wounded soldiers returning from Iraq.

Michael Conlon, Ph.D., who reported on the research, noted that the emergence of drug-resistant bacteria, which have the ability to shrug off conventional antibiotics, is a growing problem worldwide. As a result, patients need new types of antibiotics to replace drugs that no longer work.

"Frog skin is an excellent potential source of such antibiotic agents," said Conlon, a biochemist at the United Arab Emirates University in Al-Ain, Abu Dhabi Emirate. "They've been around 300 million years, so they've had plenty of time to learn how to defend themselves against disease-causing microbes in the environment. Their own environment includes polluted waterways where strong defenses against pathogens are a must."

Scientists have known for years that the skin of frogs is a rich source of chemicals capable of killing bacteria, viruses, and fungi. Researchers have attempted to isolate those germ-fighting chemicals and make them suitable for development into new antibiotics. Success, however, has been elusive because froggy antibiotics tend to be toxic to human cells and certain chemicals in the bloodstream easily destroy them.

Conlon and colleagues described an approach to overcome these problems. They discovered a way to tweak the molecular structure of frog skin antibiotic substances, making them less toxic to human cells but more powerful germ killers. Similarly, the scientists also discovered other tweaks that enabled the frog skin secretions to shrug off attack by destructive enzymes in the blood. The result was antibiotics that last longer in the bloodstream and are more likely to be effective as infection fighters, Conlon noted.

The antibiotic substances work in an unusual way that makes it very difficult for disease-causing microbes to develop resistance, Conlon said.

The scientists are currently screening skin secretions from more than 6,000 species of frogs for antibiotic activity. So far, they have purified and determined the chemical structure of barely 200, leaving a potential bonanza of antibiotic substances awaiting discovery.

"Many people are working with me, giving me samples of frog skin secretions," said Conlon, who has a dozen research collaborators in Japan, France, the United States, and other countries. "We only actually use the frogs to get the chemical structure of the antibiotic, and then we make it in the lab. We take great care not to harm these delicate creatures, and scientists return them to the wild after swabbing their skin for the precious secretions."

One substance isolated from the skin secretions of the Foothill Yellow-legged Frog -- a species once common in California and Oregon but now facing extinction -- shows promise for killing methicillin-resistant Staphylococcus aureus (MRSA) bacteria. MRSA is a "superbug," infamous for causing deadly outbreaks of infection among hospitalized patients. Now it is occurring in settings outside hospitals, including schools, nursing homes, and day care centers.

The skin of the mink frog, likewise, contains secretions that show promise for fighting "Iraqibacter," caused by multidrug-resistant Acinetobacter baumanni.

Some of the substances could make their way into clinical trials within the next five years, Conlon predicted. He envisions that pharmaceutical companies could develop the chemicals as creams or ointments for treating skin infections or as injectable drugs for treating drug-resistant infections throughout the body. The United Arab Emirates University provided funding for the study.

"The research also is important because it underscores the importance of preserving biodiversity," Conlon pointed out. "Some frog species -- including those that may contain potentially valuable medicinal substances -- are in jeopardy worldwide due to loss of habitat, water pollution, and other problems."

Scientists at Queen's University Belfast have discovered proteins in frog skins which could be used to treat cancer, diabetes, stroke and transplant patients by regulating the growth of blood vessels.
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The award-winning research, led by Professor Chris Shaw at Queen's School of Pharmacy, has identified two proteins, or 'peptides', which can be used in a controlled and targeted way to regulate 'angiogenesis' -- the process by which blood vessels grow in the body. The discovery holds the potential to develop new treatments for more than seventy major diseases and conditions that affect more than one billion people worldwide.

The proteins are found in secretions on the skins of the Waxy Monkey Frog and the Giant Firebellied Toad. Scientists capture the frogs and gently extract the secretions, before releasing them back in to the wild. The frogs are not harmed in any way during this process.

Professor Shaw said: "The proteins that we have discovered have the ability to either stimulate or inhibit the growth of blood vessels. By 'switching off' angiogenesis and inhibiting blood vessel growth, a protein from the Waxy Monkey Frog has the potential to kill cancer tumours. Most cancer tumours can only grow to a certain size before they need blood vessels to grow into the tumour to supply it with vital oxygen and nutrients. Stopping the blood vessels from growing will make the tumour less likely to spread and may eventually kill it. This has the potential to transform cancer from a terminal illness into a chronic condition.

"On the other hand, a protein from the Giant Firebellied Toad has been found to 'switch on' angiogenesis and stimulate blood vessel growth. This has the potential to treat an array of diseases and conditions that require blood vessels to repair quickly, such as wound healing, organ transplants, diabetic ulcers, and damage caused by strokes or heart conditions."

Explaining how his research team looks to the natural world to solve problems where other methods of drug discovery have failed, Professor Shaw said: "Because of its huge potential, angiogenesis has been a prime target for drugs development research over the past forty years. But despite an investment of around $4-5 billion by scientists and drugs companies around the world, they have yet to develop a drug that can effectively target, control and regulate the growth of blood vessels.

"The aim of our work at Queen's is to unlock the potential of the natural world -- in this case the secretions found on frog and toad skins -- to alleviate human suffering. We are absolutely convinced that the natural world holds the solutions to many of our problems, we just need to pose the right questions to find them.

"It would be a great shame to have something in nature that is potentially the wonder drug to treat cancer and not aim to do everything in our power to make it work."

The Queen's researchers will receive the Commendation in the Cardiovasular Innovation Award at the Medical Futures Innovation Awards in London June 6, 2011. The Awards are one of Europe's most prestigious healthcare and business awards, rewarding innovative ideas from front line clinicians, scientists and entrepreneurs. Professor Shaw's team are the only entry from Northern Ireland to be successful at this year's awards.

Congratulating Professor Shaw and his colleagues, Professor Brian Walker and Dr Tianbao Chen, on their commendation award, Queen's Vice-Chancellor Professor Peter Gregson said: "This award is not only an honour for Professor Shaw and his team, it is recognition of the world-class research taking place at Queen's School of Pharmacy, and the life-changing potential of the University's work in drug discovery."

For more information on the Medical Futures Innovation Awards 2011 visit: www.medicalfutures.co.uk