Price et al. [(1999). J. Bacteriol. 181:2358–2362] conducted a genetic study of the toxin transport protein (PA) of Bacillus anthracis, the bacterium that causes anthrax in humans. Within the 2294-nucleotide gene in 26 strains they identified five point mutations—two missense and three synonyms—among different isolates. Necropsy samples from an anthrax outbreak in 1979 revealed a novel missense mutation and five unique nucleotide changes among ten victims. The authors concluded that these data indicate little or no horizontal transfer between different B. anthracis strains.

Which types of nucleotide changes (missense or synonyms) cause amino acid changes?

Video transcript

Hi, everybody. Let's look at our next question. It says the B anthracis genome is tripartite and comprised of a singular circular chromosome and two circular variance plasma. It's The PX 01 plasma has P A G A protective antigen and an intra membrane toxin transporter L E F lethal factor, which is a zinc dependent endo proteus and C Y A M A factor, which is a cow module and sensitive ventilate cyclists. The P X 02 plasmid carries the capsule bio synthesis genes found in a cluster and is essential for full anthrax disease, which strain is commonly used as a live veterinarian vaccine and which strain was investigated during the anthrax letter attack respectively. When we look at our answer choices, we have different strains of things but not all of them are anthrax strains. So we're looking for a choice of two different anthrax strains. And the only one here is choice, see the stern strain and the Ames strain. So we don't even need to at first figure out which is which because only one of our answers has to anthrax strains. Um When we look at choice A um E I E C strain and EEC strain. These strains of E coli and Taro invasive equal I and Taro aggregated E coli both our food pathogens and cause various serious diarrheal symptoms. So they're not anthrax at all, which is so they're not our answer. Choice. Choice. B W S one A strain and the Ames strain while Ames strain is anthrax, but W S A one is a strain of B sub Tillis, which was a benign organism is a bacteria that can existence for form like anthrax. But it doesn't generally cause disease and can actually be used as a probiotic as a beneficial probiotic. It can also be used to produce different enzymes and chemical products in genetic engineering. Um This particular strain is one that's seen as a fish probiotic promise. So that's not anthrax. There we go. Even though the Ames strain is an anthrax stream, that's why choice B is not our correct answer. And then finally choice D the stern strain and the YB S stream YB S 29 is another strain of B Sub Tillis that is a probiotic. So not anthrax and therefore not our answer. Um Just to be more thorough, we can look at our answer of stern strain and aim stream. The stern stream is missing this P X 02 plasma. And as we saw on our answer, choice, the P X 02 plasma carries the capsule genes that are needed for full anthrax disease. So as you can imagine a version of the anthrax bacteria that cannot cause the full version of the disease is a very good candidate for a live veterinary vaccine as it helps build immunity to the anthrax disease um without causing that disease itself. So that's the stern strain, the live veterinary vaccine and then the Ames strain um was used in the anthrax letter attacks. It does cause a full blown anthrax disease and killed a number of people in those attacks. And in the course of that investigation, the criminal investigation, that strain was fully sequenced, very thoroughly investigated. And that led to um greater knowledge about anthrax and the ability to trace and categorize different strains of anthrax. So the Ames strain is the strain investigated during the letter attacks. So again, which strain is commonly used as a live veterinarian vaccine and which strain was investigated during the anthrax letter attack respectively. Choice see the stern strain and the Ames strain. See you in the next video.