A 50-cent microscope that folds together from a sheet of paper will make diagnosing diseases and citizen science disruptively accessible.
"Foldscope is an origami-based print-and-fold optical microscope that can be assembled from a flat sheet of paper. Although it costs less than a dollar in parts, it can provide over 2,000X magnification with sub-micron resolution (800nm), weighs less than two nickels (8.8 g), is small enough to fit in a pocket (70 × 20 × 2 mm3), requires no external power, and can survive being dropped from a 3-story building or stepped on by a person. Its minimalistic, scalable design is inherently application-specific instead of general-purpose gearing towards applications in global health, field based citizen science and K12-science education."
Somehow, these Giant microbes manage to make sexually transmitted infections cute. My personal favorites are actually the aquatic microbes, especially the Anabaena, which is a nitrogen fixer. They have a heterocyst and everything!
Take home message for me: it’s good to let your children eat dirt - it’s one of the ways we get good microbes into our guts!
|—||Felix d’Herelle, 1915, describing his first observation of the action of viruses that infect bacteria. d’Herelle coined the term bacteriophages for these viruses and began the field of phage therapy.|
Pathogenic bacteria have some wicked tricks, and this is one of them. M cells are a type of cell lining the intestine that allow the body to transport antigens in the gastrointestinal system to the immune system so that a response may be mounted. Salmonella cells (and Shigella cells) can trick the M cell into taking them inside, where they multiply and cause disease. The pink rods in the image above are the Salmonella; the ruffling of the M cell ( in yellow) is induced by the Salmonella.
Photo: Rocky Mountain Laboratories, NIAID, NIH
Researchers have found a fossil site in Chile with multiple layers of what appear to be mass strandings of marine animals, suggesting that these events were common even before humans tainted the environment.
So what do they think caused these die-offs? Microbes of course! Specifically, large blooms of dinoflagellates that produce toxins.
Parasitic Amoeba Chomps on Human Cells to Kill Them
Amoebae — a group of amorphous, single-celled organisms that live in the human body — can kill human cells by biting off chunks of intestinal cells until they die, a new study finds.
This is the first time scientists have seen this method of cell killing, and the new findings could one day help treat parasitic infections that kill children across the globe, the researchers said.
Investigators analyzed the amoeba (Entamoeba histolytica) This parasite causes amoebiasis, a sometimes-fatal diarrheal disease seen in the developing world. Amoebiasis is also a problem in the developed world — for instance, among travelers and immigrants.
"Diarrhea is more important as a cause of child death than malaria, tuberculosis or HIV," said study author William Petri, chief of the division of infectious diseases and international health at the University of Virginia. In the slums of Dhaka, Bangladesh, for instance, one-third of all children are infected with the parasite by their first birthday, he said.
This amoeba “can slice through the gut, causing colitis, or inflammation of the colon, and spread to the liver to cause liver abscesses,” Petri said. “However, it was a mystery for 111 years, since Entamoeba histolyticawas first named, as to how it kills cells,” he added.
Scientists had suggested the amoebae kill cells before devouring them. However, the researchers now show the reverse happens: The amoebae nibble on cells to kill them.
The discovery was made by the study’s lead author, Katherine Ralston, a cell biologist at the University of Virginia.
"It was completely surprising," Petri told Live Science. "It was an observation Katy [Ralston] made that I had missed, and I’ve studied this parasite for my entire professional career — 25 years on the faculty."
Through microscopic observations, Ralston had seen hints that these amoebae were nibbling cells to death. She confirmed these findings by labeling human cells with fluorescent tags and seeing tiny, glowing bits of those cells end up within the parasites.
Single bites did not kill cells. Rather, it took many bites for cells to die, the researchers said.
This nibbling is similar to a process called trogocytosis, which is nibbling that has previously been seen by cells of the immune system. However, immune trogocytosis does not kill its targets, whereas amoebic trogocytosis does.
"This is a completely novel mechanism of cell killing," Petri said. "It remains to be seen what other organisms and what other biological processes might involve this as well."
Because trogocytosis is seen in both amoebae and humans, this might be evolutionarily ancient, “dating back well before multicellular organisms evolved,” Petri said.
Intriguingly, the amoebae likely derive little sustenance from the cells they nibble to death, the researchers said. Moreover, the amoebae do not feed on the corpses of the cells they kill — once the cells are dead, the parasites detach, effectively spitting out the corpses. The amoebae probably live mostly off the hordes of bacteria that normally live in the human gut, the researchers said.
If the amoebae aren’t getting significant nutritional value from the cells they bite to death, then why kill them? They could be doing so to evade the human immune system, the researchers suspect.
"Normally, many human cells die in the body every day, and cells known as macrophages eat these dead cells," Petri said. When macrophages eat cells, they usually release chemicals that dampen inflammation. "Maybe, by leaving dead cells around, the amoebae suppress inflammation that might otherwise hurt them," Petri said.
A better understanding of how this amoeba kills cells might lead to ways to prevent or treat amoebiasis, Petri said. For instance, this amoeba uses a unique sugar-binding protein to latch onto cells, and developing vaccines against this protein could help suppress the disease. The scientists also found that drugs that suppressed a protein unique to the amoeba stopped them from munching on the human cells.
"By targeting molecules unique to the parasite, we have a better chance of therapies that combat the amoeba without affecting humans," Petri said.
The scientists detail their findings in the April 10 issue of the journal Nature.
Frontline has put out another great episode related to microbiology - this one on the tuberculosis pandemic. In the US we may think of tuberculosis as a disease of the past, but nearly 9 million people worldwide contract TB each year and more than 1 million people die. Because it is caused by a mycobacterium, there are few drugs that can treat it, and drug resistance is emerging.
More information: WHO
They’re Microbial Condominiums
Stromatolites. These are mineralized microbial communities, formed from blue-green algae (also called cyanobacteria). Over the last 4000 years, algae growing in this area have trapped detritus and sediment, forming large, living rafts known as microbial mats. The secretion of calcium carbonate by the algae has caused the mats to mineralize, forming the rock-like structures seen here. The stromatolites are known as living fossils, because the process of mat formation and mineralization continues today. They are a major constituent of the fossil record for about the first 3.5 billion years of life on earth. Modern stromatolites are mostly found in hypersaline lakes and marine lagoons where extreme conditions due to high saline levels exclude animal grazing. One such location is Hamelin Pool Marine Nature Reserve, Shark Bay in Western Australia where excellent specimens are observed today.
© Frans Lanting / MINT Images / Science Source
30-40% of people carry Staph aureus in their noses, a bacterium that can cause skin infections, surgical infections, and, in rare cases, toxic shock syndrome and food poisoning. Turns out that the presence of triclosan in nasal secretions (which happens because of triclosan is soaps and other products people use) leads to increased chance of colonization by Staph aureus in the nose. More evidence that triclosan in everyday products is not just useless, but potentially dangerous!
Article in mBio