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Web Date: August 20, 2012

Proteins Revealed In Fire Ant Venom

Proteomics: Mass spectrometry detects 46 venom proteins that shed light on fire ants’ behavior
Department: Science & Technology | Collection: Critter Chemistry, Life Sciences
News Channels: Analytical SCENE, Biological SCENE
Keywords: venom, proteomic analysis, mass spectrometry, fire ant, Solenopsis invicta
Pleased to Envenomate You
Proteins in the venom of Solenopsis invicta tell a story of the invasive fire ant species.
Credit: Luis Augusto Martelli Filho
Photograph of fire ant.
Pleased to Envenomate You
Proteins in the venom of Solenopsis invicta tell a story of the invasive fire ant species.
Credit: Luis Augusto Martelli Filho

The painful sting of the fire ant may be familiar to many Americans, but the proteins that make up the potent venom have remained largely unknown. Researchers have now used mass spectrometry to identify 46 proteins in the venom of Solenopsis invicta, an invasive species of fire ant (J. Proteome Res., DOI: 10.1021/pr300451g). They say the proteins could inspire drug discovery.

S. invicta is native to South America but now lives in the southern U.S., China, Australia, and elsewhere. Each ant produces very little venom, less than 1 µg. Proteins make up only a small portion of the venom, adding up to just a few nanograms per ant, with the rest consisting of basic compounds called alkaloids. The scarcity of venom proteins, and the difficulty of separating them from the alkaloids, has made them hard to study.

Mario Palma of the University of São Paulo State, in Brazil, special ordered a few milligrams of fire-ant venom protein that was free from alkaloids from Vespa Labs, a company that collects and purifies venoms, and analyzed the sample with two-dimensional gel electrophoresis. “We were surprised,” says Palma. “Compared to other ants, the number of proteins in the gel was small.”

They figured that some of the proteins in the venom must be too low in abundance to appear on the gel, so they decided to study the venom protein directly with mass spectrometry. The researchers added a protease to the sample. Then, they separated the fragments with a chromatography column that fed the protein pieces directly into a high-resolution mass spectrometer. Based on the masses from the fragments, they could work out the sequence of the parent proteins. Using an online protein database called Matrix Science, they identified 46 proteins based on their similarity to proteins from other ant species, snakes, spiders, wasps, and bees.

“We found a series of neurotoxins,” says Palma. “These aren’t common in social insects.” This finding may explain why some victims of the ants’ stings experience hallucinations, he says. The discovery also provides doctors with potentially useful information when treating the victims. Some scientists also think neurotoxins could find use as treatments for neurodegenerative diseases, Palma says.

Besides finding other types of harmful proteins, the researchers also spotted proteins that seem to have nothing to do with venom function, such as muscle proteins. These nonvenomous proteins may be artifacts of the method that the supplier had used to extract venom from the ant, and may not actually belong in the venom, Palma says.

The researchers also discovered proteins that likely function to benefit ant society. A few of the proteins kill bacteria, Palma says, which may explain a puzzling behavior that scientists have observed: The ants spray their venom around their nests. Other venom proteins bind pheromones and may help the fire ant lay down a chemical trail to communicate alarm or aggression to other colony members.

“It’s an excellent paper,” says Donald Hoffman, who recently retired from East Carolina University. It should provide fodder for entomological and medical research, he says. Palma plans to synthesize some of the proteins in his laboratory to study their biological function and pharmaceutical potential in more detail.

Chemical & Engineering News
ISSN 0009-2347
Copyright © American Chemical Society
Nathan (September 13, 2012 10:13 PM)
Interesting! However I would differ in several aspects: “Compared to other ants, the number of proteins in the gel was small.” -- I really do not think that many ant venoms were analyzed to date, and in fact many seem to completely lack proteins! Carpenter ants, devil-garden ants, most Dolichoderinae... instances abound! "A few of the proteins kill bacteria, Palma says, which may explain a puzzling behavior that scientists have observed: The ants spray their venom around their nests." -- Errrr, actually I am puzzled that this study did not test the antibacterial properties of any proteins, did it? I wonder which these would be, from the *tentative* protein list given. Moreover, I do think this "puzzling" behavior, known as "gaster-flagging", is in fact not any mystery, given that fire ant venom is over 95% volatile antifungal venom alkaloids, and was observed in other ant groups as well. "Other venom proteins bind pheromones..." -- I should remark that many venom allergens are part of the odorant-binding class of proteins, and that this is no novelty, and does not necessarily mean they are truly chemical cues. Maybe this study would have greatly benefitted from a tougher review prior to publication..? Maybe some colleagues will feel the same way.
Dr. OW (December 19, 2012 9:45 PM)
Eerrr, a better question, still: where are the raw sequences? Any respectable bioinformatics study deposits all obtained sequences in open databases for public view. This, in addition to help colleagues, adds reliability to the study, as anyone can check the results.

I suspect any study lacking raw data and transparency. Also I find it remarkable that the responsible editor is geographically close to authors... nothing meant by this.
thomas maurer (April 30, 2013 10:35 PM)
I received 450 stings & then in @ 10 min was in anaphylactic shock. I've had 20-30 before w/o incident. Now the ER wants me to determine if I'm allergic. Personally I think that much venom will bring anyone down!
Joan Senyk (July 21, 2013 9:56 AM)
How do you treat the bites? Lydocaine gel and 2.5% cortisone cream had no effect. Only baking soda had a mild effect.
Connie (September 9, 2015 11:35 AM)
I am anaphylactic to fire ant stings, my blood pressure drops and I pass out, the question I have is the other day, I was stung 6 times by a fire ant, my husband gave me the eipen shot and I really had no reaction, can you tell me are there different fire ants that may carry more of something else that I might be allergic too, is a fire ant all the same, or am I getting to were I am not allergic anymore. Thank you
sylvia (January 7, 2016 6:28 PM)
hello I was in Honolulu in December 2015 and I was stung by a fire/and or a scorpion. The sting was very painful for about 10minutes. But I could not see any puncture in my toe. So I thought that my bone in my foot splintered. do to the awful pain. The next day my little toe was blue and red and very swollen. It looked like a huge opaque blister on my toe. I used hydrogen peroxide to clean it and Neosporin. It was sore but I could walk. Several days later I had awful pain in my lower part of my body and I noticed that my right leg with the sting toe was red and blue in color and twice the size of my other leg. I went to see a doctor and he was not sure if it was a fire/ant or a scorpion sting. He gave me some anti/cream for my toe and suggested to return home. I did and I saw a doctor he took some blood tests and it showed an infection like UTI. but I knew that it was not a UTI because the symptoms were not there. He suggested to wait for an antibiotic for 2 months...I don't know what planet he came from. I have been sick since with high blood pressure/high pulse rate and shortness of breath, pain in my chest and constant nose bleeds.
I am finally going to the clinic again because it makes no sense to me to wait 2 months for an antibiotic.
I wish someone could tell me how long it takes for the venom to work itself out of the system of the body...
Bea (September 23, 2016 10:14 AM)
I realize that this is a 4 year old paper. That being said, I wonder if anyone has had any progress in the study of the fire ant proteins and specifically if they have, for the benefit of all that will be stung, developed an antivenin. At first I thought that it would be extremely helpful if an antivenin that could be dispersed in water could be developed. I believe but do not know for certain just a guess based on personal experience that most of the time people get stung on either their feet or hands. It would be beneficial if something could be developed in which to soak said extremities. However, I have since consider that a drawing agent such as a salve might also be helpful and easier for the sting victim to manage. In the "olden days" there used to be an either coal or tree tar based salve that was thought to draw out toxins when applied. Whether this was actually the case or a placebo effect is unknown to me. Nevertheless, it seems a good place to start trying to find something that will help those that suffer from the stings of these little devils as they are not going to disappear. I am relatively certain that there is money to be made in the development of something that will alleviate fire ant venom symptoms.
bruce franc (January 7, 2017 4:22 PM)
I loved all the comments and the initial article. Knowing that the solenopsin is a toxic alkaloid should suggest some relief. I used white vinegar. But I must admit insect bites rarely bother me for long. I will check this compound out and see what in the cupboard maybe more effective.
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