Monday, January 18, 2021

444 - Strange Sequence Stops Cell Subjugation

T4 Bacteriophage
By Victoramuse,
CC BY-SA 4.0
This episode: An interesting bacterial genetic element protects against viruses in a unique way!

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Show notes:
Microbe of the episode: Mongoose associated gemykibivirus 1


Takeaways
Even single-celled, microscopic organisms such as bacteria have to deal with deadly viruses infecting them. And while they don't have an immune system with antibodies and macrophages like we do, they still have defenses against infection, mostly based on sensing and destroying viral genomes. Restriction enzymes cut viral genomes at specific places, and CRISPR/Cas targets and destroys specific viral sequences. Knowing this, when microbiologists contemplate a strange genetic element of unknown function in bacteria, it's worth considering that it may be relevant to defense against phages.

The strange element in this case is retrons: a special reverse transcriptase enzyme takes a short non-coding RNA transcript and transcribes it into DNA, then links the RNA and DNA sequences together. These retrons are found in a variety of forms in a variety of microbes, and their function has been unknown up till now. In this study, one specific retron was found to defend bacteria against a number of phages. By comparing viruses, they discovered that this retron functions by sensing viruses' attempts to defeat another bacterial defense, a sort of second level of defenses. How common such a system is, what variants may exist, and how we may be able to use it for research or biotech purposes remain to be determined.

Journal Paper:
>Millman A, Bernheim A, Stokar-Avihail A, Fedorenko T, Voichek M, Leavitt A, Oppenheimer-Shaanan Y, Sorek R. 2020. Bacterial Retrons Function In Anti-Phage Defense. Cell 183:1551-1561.e12.

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Monday, January 11, 2021

443 - Gut Group Gives Gamma Guard

Lachnospiraceae
By Public Health Image Library
Attribution
This episode: Certain gut microbes protect mice from harmful effects of high-energy radiation!

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Show notes:
Microbe of the episode: Solenopsis invicta virus-1


Takeaways
High-energy radiation can be very dangerous. Besides a long-term increased risk of cancer due to DNA damage, a high enough dose of radiation can cause lethal damage to multiple systems in the body, especially the gastrointestinal tract and the immune system. Finding new ways to treat or prevent damage from radiation would be very helpful for improving the safety of space travel, nuclear energy, and radiotherapy for cancer.

In this study, some mice exposed to a typically lethal dose of radiation survived without ill effects, thanks to certain microbes in their gut. Transferring these microbes to other mice helped those mice survive radiation as well, and even just the metabolites that the bacteria produced were helpful for protecting the cells in the body most affected by radiation.

Journal Paper:
Guo H, Chou W-C, Lai Y, Liang K, Tam JW, Brickey WJ, Chen L, Montgomery ND, Li X, Bohannon LM, Sung AD, Chao NJ, Peled JU, Gomes ALC, van den Brink MRM, French MJ, Macintyre AN, Sempowski GD, Tan X, Sartor RB, Lu K, Ting JPY. 2020. Multi-omics analyses of radiation survivors identify radioprotective microbes and metabolites. Science 370:eaay9097.

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Monday, December 28, 2020

442 - Fossil Phototroph Phagocytosis

Fossilized coccolithophores
By Gibbs et al. 2020
Sci Adv 6:eabc9123
CC BY-NC 4.0
This episode: Algae surviving impact that killed the dinosaurs seem to have consumed other organisms to make it through the dark times!

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Show notes:
Microbe of the episode: Chaetoceros tenuissimus RNA virus 01


Takeaways
Being able to look through time and learn about what might have happened to creatures throughout Earth's history is what makes paleontology great. Everyone knows about dinosaurs and what happened to them at the end of the Cretaceous period thanks to science. But what we can learn is not limited just to large organisms; there are ways to learn about microorganisms of the past as well, including by looking at fossils!

In this study, fossils of hard-shelled algae from around the end of the dinosaurs show that many of these microbes in the oceans went extinct at the same time due to the massive space impact. Debris blocked out sunlight for years, making it difficult for photosynthetic organisms to survive. So some of these algae appear to have survived by preying on smaller organisms, pulling them in through a hole in their shell.

Journal Paper:
Gibbs SJ, Bown PR, Ward BA, Alvarez SA, Kim H, Archontikis OA, Sauterey B, Poulton AJ, Wilson J, Ridgwell A. 2020. Algal plankton turn to hunting to survive and recover from end-Cretaceous impact darkness. Sci Adv 6:eabc9123.
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Monday, December 21, 2020

441 - Hyphal Hijacker Helps Harvests

Fungus growing in root
By Zhang et al. 2020
Molec Plant 13:1420-1433
CC BY-NC-ND 4.0
This episode: A fungus-infecting virus transforms the fungal foe into a friend of its host plant!

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Show notes:
Microbe of the episode: Hepacivirus J


Takeaways
Viruses can be useful for treating various diseases, especially bacterial infections and cancer. Their ability to target certain cell types specifically makes them great at hunting down and killing disease-causing cells without harming the body's healthy tissue. And just as bacteriophages can work to treat bacterial disease in us, fungal viruses could help to treat serious fungal infections in crop plants.

In this study, a fungus-infecting virus goes beyond treating a deadly fungal disease in rapeseed plants. Fungus infected with this virus no longer causes disease, but lives in harmony with the host plant, protects it from other fungal diseases, and even helps it to grow better.

Journal Paper:
Zhang H, Xie J, Fu Y, Cheng J, Qu Z, Zhao Z, Cheng S, Chen T, Li B, Wang Q, Liu X, Tian B, Collinge DB, Jiang D. 2020. A 2-kb Mycovirus Converts a Pathogenic Fungus into a Beneficial Endophyte for Brassica Protection and Yield Enhancement. Mol Plant 13:1420–1433.

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Monday, December 14, 2020

440 - Prokaryotes Pay for Passage

Bacteria along fungal hyphae
By Abeysinghe et al. 2020,
Life Sci Alliance 3:e202000878
CC BY 4.0
This episode: Bacteria pay for the privilege of cruising around soil on fungus filaments!

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Show notes:
Microbe of the episode: Clostridium acetobutylicum


Takeaways
In the complex environment of soil, many different kinds of organisms coexist. Some compete with each other, while others cooperate in fascinating interactions. One example is how bacteria can swim through a film of water surrounding the filaments of fungi, allowing them to traverse more quickly and reach new locations.

In this study, an interaction between fungus and bacterium is discovered in which the bacteria benefit from the fungus in enhanced ability to travel, and the fungus benefits by absorbing vitamins that the bacteria produce.

Journal Paper:
Abeysinghe G, Kuchira M, Kudo G, Masuo S, Ninomiya A, Takahashi K, Utada AS, Hagiwara D, Nomura N, Takaya N, Obana N, Takeshita N. 2020. Fungal mycelia and bacterial thiamine establish a mutualistic growth mechanism. Life Sci Alliance 3(12):202000878.

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Monday, November 30, 2020

439 - Microbes Mitigate Mushroom Morbidity

Button mushrooms
By chris_73, CC BY-SA 3.0
This episode: Bacteria protect farmed mushrooms from damage by other bacteria by breaking down their toxins!

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Show notes:
Microbe of the episode: Tomato mosaic virus

Takeaways
Almost all organisms are vulnerable to pathogenic microbes that make them sick or cause damage. Most also have other microbes that help them grow better or protect them from pathogens. This includes animals, plants, and also fungi.

In this study, bacterial pathogens produce a toxin that causes button mushrooms to turn brown and rot. However, other bacteria can degrade this toxin and protect the fungus, and can also degrade molecules the pathogens produce to help them swarm to new places, restricting their movement.

Journal Paper:
Hermenau R, Kugel S, Komor AJ, Hertweck C. 2020. Helper bacteria halt and disarm mushroom pathogens by linearizing structurally diverse cyclolipopeptides. Proc Natl Acad Sci 117:23802–23806.

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Monday, November 16, 2020

438 - Bacteria Bait Bug Babies

Drosophila fruit fly
By André Karwath
CC BY-SA 2.5
This episode: Actinomycete bacteria are often helpful to insects, but some can be deadly yet still attractive!

Download Episode (5.7 MB, 8.3 minutes)

Show notes:
Microbe of the episode: Streptomyces corchorusii


Takeaways
Actinomycete bacteria do a lot of interesting things. They grow like fungi, with mycelia and spores, and produce many interesting compounds, including antibiotics and other useful pharmaceuticals. They often team up with insects, producing such compounds to assist them in competing with other organisms or resisting disease.

But such amazingly helpful powers of chemistry can also be amazingly harmful. In this study, multiple strains of these bacteria were able to kill fruit fly larvae that ingested their spores. The toxin the bacteria produced was a chemical that interferes with cells' DNA-protein interactions. The bacteria also produced an odor that, in certain concentrations, lured the larvae to their doom.

Journal Paper:
Ho LK, Daniel-Ivad M, Jeedigunta SP, Li J, Iliadi KG, Boulianne GL, Hurd TR, Smibert CA, Nodwell JR. 2020. Chemical entrapment and killing of insects by bacteria. Nat Commun 11:4608.

Other interesting stories:
Also news, Feedspot ranked BacterioFiles in the top 5 virology podcasts! Check out the list for other good shows about viruses.

Post questions or comments here or email to bacteriofiles@gmail.com. Thanks for listening!

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