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Posts tagged "biology"


Calm Down: Ancient Environmental Viruses Aren’t a Threat

You may have seen recently that scientists recovered and “revived” a giant virus from Siberian permafrost (frozen soil) that dates back 30,000 years.

The researchers raised concerns that drilling in the permafrost may expose us to many more pathogenic viruses. Should we be worried about being infected from the past? Can human viruses survive in this permafrost environment and come back to wreak havoc?

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The human body is utterly wild, isn’t it? So many things go into our health and even the timing of bad health. 

How T Cells Work


Sharks don’t just swim. Some walk. See what a walking shark looks like and watch the story of its surprise 2012 discovery in this new video short, the first in a new series by The Pew Charitable Trusts.

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The Worm Wagon

The top image in this trio shows a close up of an adult Trichuris muris, a whipworm parasite. Here the worm is seen under an electron microscope but more commonly this type of worm is seen taking residence in the large intestine of its host. 

In the second image you can see illustrations of Schistosoma mansoni by Paul Evans © 2012. This parasite lives in the blood and lays thousands of eggs which result in tissue damage and even death.

BBSRC-funded Sheena Cruickshank (centre of picture) and Professor Kathryn Else (right), are lecturers at The University of Manchester who specialise in studying parasites. Both are co-founders, with Dr Jo Pennock (left), of the outreach activity called The Worm Wagon: an exhibition that is part of the BBSRC’s 20th Anniversary Festival. This exhibit will focus on explaining how people catch infections and the global significance of these infections.

When not on the Worm Wagon their day to day research tries to understand the biology and immunology of parasite infection. Part of Sheena’s research is finding markers we can use to help diagnose patients who respond badly to infection and those who don’t. Professor Else concentrates more on vaccine research and how the damage caused by infection is regulated.

This research is vital considering the biggest killer of people under 50 is infection.

Images of Trichuris muris from Uta Rossler, Richard Grencis and Toby Starborg FLS, UoM.

Image of researchers by Mark Waugh, UoM.

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Segenet Kelemu, 2014 L’Oréal-UNESCO Awards Laureate for Africa and the Arab States

Dr. Segenet KELEMU, Director General, International Center for Insect Physiology and Ecology, (ICIPE), Nairobi, Kenya, Honored for improving the resistance and productivity of tropical and sub-tropical forage grasses via the use of microorganisms

The main food source for much of the world’s livestock, forage grasses are vitally important to meeting the increasing demand for meat and milk. Dr. Segenet Kelemu has been recognized for her research on how microbes living in symbiosis with these grasses influence their health, their capacity to adapt to environmental stress and their ability to resist disease. By enabling small-scale farmers in tropical and sub-tropical regions to choose the most productive, most pathogen-resistant forage grasses, her work has both helped them improve their lives and increase supplies of much-needed animal proteins.

In particular, Dr. Kelemu’s research on Brachiaria grasses has shown that their capacity to thrive in diverse environments is related to an endophyte fungus which lives within these plants, protects them and exists in symbiosis with them. Her work has led to solutions for disruptions in food supplies caused by pathogenic organisms and extreme climatic conditions and may help to determine which microbes allow crops to survive environmental alterations.

via For Women in Science.

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Viruses Reconsidered

"The discovery of more and more viruses of record-breaking size calls for a reclassification of life on Earth."

The theory of evolution was first proposed based on visual observations of animals and plants. Then, in the latter half of the 19th century, the invention of the modern optical microscope helped scientists begin to systematically explore the vast world of previously invisible organisms, dubbed “microbes” by the late, great Louis Pasteur, and led to a rethinking of the classification of living things.

In the mid-1970s, based on the analysis of the ribosomal genes of these organisms, Carl Woese and others proposed a classification that divided living organisms into three domains: eukaryotes, bacteria, and archaea. (See “Discovering Archaea, 1977,” The Scientist, March 2014) Even though viruses were by that time visible using electron microscopes, they were left off the tree of life because they did not possess the ribosomal genes typically used in phylogenetic analyses. And viruses are still largely considered to be nonliving biomolecules—a characterization spurred, in part, by the work of 1946 Nobel laureate Wendell Meredith Stanley, who in 1935 succeeded in crystallizing the tobacco mosaic virus. Even after crystallization, the virus maintained its biological properties, such as its ability to infect cells, suggesting to Stanley that the virus could not be truly alive.

Recently, however, the discovery of numerous giant virus species—with dimensions and genome sizes that rival those of many microbes—has challenged these views. In 2003, my colleagues and I announced the discovery of Mimivirus, a parasite of amoebae that researchers had for years considered a bacterium. With a diameter of 0.4 micrometers (μm) and a 1.2-megabase-pair DNA genome, the virus defied the predominant notion that viruses could never exceed 0.2 μm. Since then, a number of other startlingly large viruses have been discovered, most recently two Pandoraviruses in July 2013, also inside amoebas. Those viruses harbor genomes of 1.9 million and 2.5 million bases, and for more than 15 years had been considered parasitic eukaryotes that infected amoebas.

Now, with the advent of whole-genome sequencing, researchers are beginning to realize that most organisms are in fact chimeras containing genes from many different sources—eukaryotic, prokaryotic, and viral alike—leading us to rethink evolution, especially the extent of gene flow between the visible and microscopic worlds. Genomic analysis has, for example, suggested that eukaryotes are the result of ancient interactions between bacteria and archaea. In this context, viruses are becoming more widely recognized as shuttles of genetic material, with metagenomic studies suggesting that the billions of viruses on Earth harbor more genetic information than the rest of the living world combined. These studies point to viruses being at least as critical in the evolution of life as all the other organisms on Earth.

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Teleost Fishes (Teleostei) is one of three infraclasses in class Actinopterygii, the ray-finned fishes. This diverse group, which arose in theTriassic period, includes 26,840 extant species in about 40 orders and 448 families; most living fishes are members of this group. The other two infraclasses, Holostei and Chondrostei, may be paraphyletic.

Some teleost fish have also developed jet propulsion, passing water through the gills to supplement fin-driven motion.

The oldest teleost fossils date back to early Triassic, possibly evolving from fish related to the bowfin in the clade Holostei. During the Mesozoic and Cenozoic they diversified and as a result, 96% of all known fish species are teleosts. Teleosts are here divided into twelve superorders, but this system is unlikely to be entirely correct and is in the process of being studied.



  1. Mexichromis mariei
    Size: 1.2 in (3 cm)
  2. Pteraeolidia ianthina
    Size: 5.9 in (15 cm)
  3. Phyllidia ocellata
    Size: 2.4 in (6 cm)
  4. Phyllidiella pustulosa
    Size: 2.4 in (6 cm)
  5. Godiva sp.
    Size: 1.6 in (4 cm)
  6. Hypselodoris sp.
    Size: 2 in (5 cm)
  7. A quartet of Risbecia tryoni nudibranchs show the beginnings of trailing behavior, in which the animals follow one another’s slime trails, each hot on the tail of the next. (It often occurs in pairs.) Scientists once thought trailing was related to mating, but evidence is thin; its true purpose remains unknown.

Photography by David Doubilet


Sea peach fluorescence

Sea peaches (Halocynthia aurantium) are of the order Stolidobranchia, making them a sub-classification of Tunicates. Sea peaches are commonly found in the northern Pacific ocean, ranging from the Arctic Sea south to Puget Sound, and most common in the Bering Sea at a depth of 40 to 100 metres. The sea peach is typically barrel shaped, growing to a height of 18 centimeters, and its body is attached directly to the substrate. It is usually red or orange with a smooth or wrinkled tunic. There are two siphons at the top. The sea peach is preyed upon by crabs and sea stars.

Image Credit: Alexander Semenov



What is Leprosy?

Leprosy has afflicted humankind for thousands of years, being recognised and recorded in many ancient civilisations, but the disease isn’t a thing of the past. Every year, up to 300,000 people are diagnosed with leprosy, and up to 3 million people are currently disabled because of it.

Also known as Hansen’s Disease, leprosy is a chronic infection caused by a bacterium called Mycobacterium leprae, which is a slow-growing pathogen that can only live inside its host. This makes research difficult, as animals must be used to grow them and it may take twenty years for symptoms to appear. Leprosy mainly affects the periphery nerves (those outside of the brain and spinal cord), and it’s characterised by skin lesions and sensory loss—eventually, if untreated, sufferers will lose sensation in hands and feet.

Contrary to popular belief, it can’t be caught by touch. Although researchers aren’t 100% sure, they believe it’s caught through broken skin or droplets of moisture passed through the air by untreated sufferers. Because symptoms are so slow to appear, people may not realise they’re infected until they’re five or ten years into the disease, but the good news is it’s thought to be partially genetic—so 95% of people are naturally immune.

Today, it’s most common in places of poverty where low standards of living weakens people’s immune systems. Myth and superstition still perpetuate crippling stigma, and those diagnosed with leprosy can be rejected by their families and communities, but quarantine and segregeation are unnecessary. Leprosy isn’t as contagious as superstition dictates—those who are treated can lose their infectiousness after as little as two weeks.

The Leprosy Mission International


How Breast Milk Engineers a Baby’s Gut (and Gut Microbes)

Raising an infant is an act of ecosystem engineering. You’re not just caring for a baby, but an entire world.

Right from birth, babies are colonized by legions of microbes that set up shop in their guts, skin, and more. These are vital. They help the growing human to digest its food, and to keep harmful microbes away. They are so important that newborns temporarily suppress their own immune system to give their microbial partners a chance to establish themselves.

Mom helps too. Her vaginal secretions provide her child with a starter pack of microbes. And her breast milk contains special sugars that seem to selectively nourish the gut bacteria that infants need.

Now, Eric Rogier from the University of Kentucky has found a milk antibody called SIgA also helps to set up the right community of gut microbes. Without it, young mice face long-lasting consequences, including several signs of inflammatory bowel diseases (IBD).  This antibody sets up a healthier environment in an infant’s intestinal tract, so they’re better prepared to withstand environmental problems later in life,” says Charlotte Kaetzel, who led the study.

Although the team only looked at mice, Kaetzel notes that several studies have found that breastfed babies are less likely to develop IBD later in life. “We’re not talking about black and white: you’re protected if you’re breastfed and not protected if you aren’t,” she says. “But I’d certainly argue that there’s a clear benefit.”

“We now recognize more and more that factors in breast milk influence the gut microbiota, which in turn sets up the immune system to have fewer chronic illnesses later in life,” says Allan Walker from Massachusetts General Hospital.

Milk contains a vast cocktail of molecules, and immunoglobin A (IgA or SIgA) is one of them. It’s an antibody found in our bodily secretions. We manufacture it in ridiculous amounts: around a teaspoon every day. It’s in milk, mucus, tears, saliva—anywhere where our cells shunt fluid into the outside world. Run a finger along any surface of your body and if it ends up wet, it probably has SIgA on it.

Mice and humans eventually make SIgA for themselves but in our earliest days of life, mother’s milk is the only source of the antibody. When Rogier engineered mutant mice that couldn’t produce SIgA in their milk, he found that their pups grew up with peculiar guts. They harboured with different communities of gut bacteria, and had more of certain groups that are seen in the guts of IBD patients. And some of these microbes ended up in unexpected places.

As a mouse grows up, its gut microbes interact with its own gut cells to create a sealed barrier that keeps foreign material out of the deeper intestinal tissue. The barrier is a good fence that makes for good neighbours. But if newborn mice can’t get SIgA from their mothers, their intestinal barriers are porous and bacteria pass into the underlying lymph nodes.

“These lymph nodes should be absolutely sterile,” says Kaetzel. “When you take them out of an adult mouse and culture them, you’ll find no bacteria. When we took lymph nodes from offspring who didn’t get SIgA in their milk, they were loaded with bacteria.”

The most abundant species was Ochrobactrum anthropi—an opportunistic bacterium that’s been linked to a growing number of infections in hospital patients. It also depends on oxygen, which is odd since most gut bacteria shun the stuff or, at most, tolerate it. “You typically see overgrowth of aerobic bacteria when you have inflammation,” says Kaetzel.

“Beneficial bacteria in the intestinal tract are crucial, but you don’t necessarily want them around too much, like overgrowing in the lymph nodes,” says Katie Hinde from Harvard University. “This study shows that ingested SIgA is instrumental for limiting bacterial invasion beyond the gut wall.”

These early changes persisted into adulthood and left the mice permanently susceptible to inflammation, even if they could eventually make SIgA for themselves. When the team added an inflammatory chemical called DSS into their drinking water, those that didn’t get the antibody from their mothers reacted more vigorously.Theystrongly activated several genes that have been linked to IBD in humans.

When it comes to such diseases, scientists often talk about a triad of contributing factors: the host’s own biology, their microbes, and environmental factors like food-borne illnesses that can trigger inflammation. “These mice had altered two sides of this triangle,” says Kaetzel. They didn’t get enough SIgA (a host factor), and they ended up with strange microbiota. The DSS closed the triangle and led to severe inflammation.

The team now wants to see if it’s possible to boost the intestinal health of a formula-fed infant by supplementing them with SIgA, or even if the purified antibody could help older children or adults with intestinal problems.

And, of course, their study highlights yet another benefit to breastfeeding. It’s unique in isolating the effect of a single (major) ingredient of milk, but Kaetzel notes that breastfed infants also get a wide spectrum of other helpful substances.

For example, it contains its own microbes. Lisa Funkhouser and Seth Bordenstein have speculated that the lymphatic system conveys bacteria from a mother’s guts into her mammary glands, where they can be taken up by suckling infants.

If pups that don’t get SIgA from their mothers have weird bacteria in their lymph nodes, could they then pass on different microbes to their own offspring, when the time comes for them to produce milk? “There could be some really exciting transgenerational consequences from not ingesting sIgA in mother’s milk,” says Hinde.



Mouse Large Intestine

Dr. Paul Appleton

Blairgowrie, UK

Technique: Multiphoton

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