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Monday, February 16, 2009

Wasps can sting because of an ancient virus


"The wasps' stings pack a punch partly due to paralyzing particles stripped out of an ancient virus, suggests a team led by Annie Bezier of France's Université François Rabelais."Many species of parasitoid wasps inject polydnavirus (virus-like) particles in order to manipulate host defenses and development," begins the study in the current Science magazine. Wasps use caterpillars for food, and inject their eggs into them so their growing young have a food source. The wasps also inject polydnavirus particles which paralyze the caterpillars, which allows the wasp embryos to eat from them until they kill the caterpillar and leave the caress to live out their predatory lives .Unlike real viruses, the particles don't reproduce after invading their host, and lack any genetic machinery to spawn. So, how did they get into wasps?

Bezier and colleagues opened up wasp ovaries (the calyx) of distantly-related parasitic wasps (specifically the cotesia congregata wasps), which prey particularly on young tobacco hookworms. The calyx is the only place the wasp makes the viral particles, before the particles are injecting into the caterpillar. Bezier and her associates found within the genes of the wasps the tools for reproducing the particles. And then these scientists compared those genes to known viruses, looking for a match, which they found within a family of viruses known to afflict moths, beetles, crickets and shrimp.

The researchers found that 22 calyx genes matched those from the moth virus family, with small differences suggesting they are remnants of an infection of an ancestral wasp about 100 million years ago. The researchers have "convincingly demonstrated" that this ancient virus inserted its genes into the DNA of the wasps, finds immunologist Donald Stoltz of Canada's Dalhousie University and entomologist James Whitfield of the University of Illinois, in a commentary accompanying the study.

"The authors solve a long-standing mystery, and at the same time establish a new paradigm in virology," add Stoltz and Whitfield, in a more congratulatory vein. Episodes of "horizontal" transfer of genes, wholesale borrowing of useful ones, are common among microbes, and genome researchers have long shown that animal genomes, including ours, are riddled with remnants of viral DNA that blundered their way into our genes and sometimes play useful roles, for example in the development of the placenta in pregnant women. But the wasp-virus incorporations "represent the only example, so far," say the study authors, of a creature lifting gene machinery that allows it to inject and fire off genes into another creature. The finding, they suggest, opens a new avenue for gene therapy.

More broadly, the virus finding reveals a new way for viruses and the hosts to make a living off each other, suggest Stoltz and Whitfield. The original virus doesn't seem to be around any more, but its genes live on in the belly of the wasp. "Were the (virus-like) polydnaviruses really viruses?" they ask? It all depends on how virologists define viruses, they conclude, something neglected in the most recent 1,259-page Virus Taxonomy: VIIIth Report, the bible of virology.

The more interesting lesson here for virologists and for evolutionary biologists may be that there is now reason to start thinking about virus-host relationships in much broader terms," adds the commentary. The wasp polydnavirus-style mutual back-scratching among viruses and their victims may be more common than previously supposed. "How did this kind of relationship arise?" they ask.

Sources:http://www.sciencemag.org/cgi/content/abstract/323/5916/926 and

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Thoughts worth thinking about

"Our subconscious minds have no sense of humor, play no jokes and cannot tell the difference between reality and an imagined thought or image. What we continually think about eventually will manifest in our lives."-Sidney Madwed



Laws alone can not secure freedom of expression; in order that every woman and man present their views without penalty, there must be spirit of tolerance in the entire population.- Albert Einstein Too often we underestimate the power of a touch, a smile, a kind word, a listening ear, an honest compliment, or the smallest act of caring, all of which have the potential to turn a life around. - Leo Buscaglia



A person's true wealth is the good he or she does in the world. - Mohammed



Our task must be to free ourselves... by widening our circle of compassion to embrace all living creatures and the whole of nature and its beauty. -Albert Einstein



The best way to find yourself, is to lose yourself in the service of others. - Ghandi



The unselfish effort to bring cheer to others will be the beginning of a happier life for ourselves. - Helen Keller



Aim for success, not perfection. Never give up your right to be wrong, because then you will lose the ability to learn new things and move forward with your life. Remember that fear always lurks behind perfectionism. Confronting your fears and allowing yourself the right to be human can, paradoxically, make yourself a happier and more productive person. - Dr. David M. Burns



Life is as dear to a mute creature as it is to man. Just as one wants happiness and fears pain, just as one wants to live and not die, so do other creatures. -His Holiness The Dalai Lama



Mankind's true moral test, its fundamental test (which lies deeply buried from view), consists of its attitude towards those who are at its mercy: animals. And in this respect mankind has suffered a fundamental debacle, a debacle so fundamental that all others stem from it. -



Milan Kundera, The Unbearable Lightness of Being



The worst sin towards our fellow creatures is not to hate them, but to be indifferent to them. That's the essence of inhumanity. -George Bernard Shaw

Ego's trick is to make us lose sight of our interdependence. That kind of ego-thought gives us a perfect justification to look out only for ourselves. But that is far from the truth. In reality we all depend on each other and we have to help each other. The husband has to help his wife, the wife has to help the husband, the mother has to help her children, and the children are supposed to help the parents too, whether they want to or not.-Gehlek Rinpoche Source: "The Best Buddhist Writing 2005 pg. 165

The hostile attitude of conquering nature ignores the basic interdependence of all things and events---that the world beyond the skin is actually an extension of our own bodies---and will end in destroying the very environment from which we emerge and upon which our whole life depends.