Unexpected stem cell factories found inside teeth
by Sarah C. P. Williams || 30 July 2014 || Science/AAAS | News
Development is typically thought to be a one-way street. Stem cells produce cells that mature into specific types, such as the neurons and glia that compose nervous systems, but the reverse isn’t supposed to happen.
Yet researchers have now discovered nervous system cells transforming back into stem cells in a very surprising place: inside teeth. This unexpected source of stem cells potentially offers scientists a new starting point from which to grow human tissues for therapeutic or research purposes without using embryos.
01 August 2014
Gut Bugs Attack
Diarrhoea, sickness, cramps, fever – just some of the symptoms of food poisoning. Some of us will be unlucky enough to experience these as a result of infection by a nasty gut bug known as Campylobacter jejuni, found on raw poultry such as chicken. It’s one of the leading global causes of food-related illness, yet we know little about how it infects us. To find out more, researchers are studying mice carrying a faulty version of a gene called Sigirr that are particularly prone to Campylobacter infection. Pictured is a highly magnified section of gut from one of these animals showing the bacteria (highlighted in red) aggressively attacking and invading the gut tissue (blue and green). Figuring out how cells in the gut and the wider immune system respond to this onslaught reveals more about what’s going on, and opens new approaches for more effective prevention and treatment.
Written by Kat Arney
Adapted from an image by Bruce Vallance and colleagues
Child and Family Research Institute, Canada
Originally published under a Creative Commons Licence (BY 4.0)
Research published in PLOS Pathogens, July 2014
Largest aquatic insect in the world found in China
By Bec Crew | July 22, 2014 | Scientific American Blog Network
Images have surfaced of a newly discovered insect reported to be the largest aquatic insect in the world. Found in the mountains of Chengdu in China’s Sichuan province, the specimen boasts a wingspan of 21 cm. While very little is known about the specimen at this point, it’s been identified as belonging to the order Megaloptera, which includes about 300 described species of winged alderflies, dobsonflies and fishflies.
Keeping Viral Load Low
Over the past 30 years, the combined efforts of scientists and clinicians have delivered remarkable successes in HIV therapeutics. Since 1987, the FDA has approved more than 30 antiviral drugs, including 12 HIV protease inhibitors and one integrase inhibitor. These drugs stop ~99% of viral replication, essentially transforming HIV infection from a deadly disease to a chronic one. What will the next 30 years bring?
Image: Here numerous HIV-1 particles leave a cultured HeLa cell. These viruses lack their vpu gene and thus can’t detach from the cell’s tethering factor, BST2. Each viron particle is ~120nm in diameter. The image was captured with a Zeiss Merlin ultra high-resolution scanning electron microscope. The cells were fixed, dehydrated, critical-point dried, and lightly sputter-coated with gold/palladium.
Spiny orb-weaver: the Long-winged Kite Spider - Gasteracantha versicolor
Spiny orb-weavers come in a wide variety of shapes and colors. These spiders belong to the genus Gasteracantha within the Araneidae family, and are remarkable for the hard, horny epidermis of their abdomen, which is also armed with two, four, or six prominent spines, varying in length, strength, and direction, and issuing from different points of the margin. The abdomen is also marked on the upperside, and occasionally underneath, with numerous symmetrically disposed cicatricose spots, varying a little in number, size, form, and position.
Gasteracantha versicolor is one of the about 170 species currently recognized into the genus. It is commonly named Long-winged kite spider and can be found in the tropics and sub-tropics, where it occurs in forests. It has an extensive range, from central, east and southern Africa to Madagascar.
The female of this species is 8 to 10 mm long, with a large, glossy and brightly colored abdomen. The hardened abdomen has six peripheral spines, with the lateral pair longer and slightly recurved. Males are much smaller, less colorful and lack the thorny abdominal projections.
Photo credit: ©Paul Bertner | Locality: Andasibe National Park, Madagascar
This graphic shows the life cycle of the ebolavirus. Bats are strongly implicated as both reservoirs and hosts for the ebolavirus. Of the five identified ebolavirus subtypes, four are capable of human-to-human transmission. Initial infections in humans result from contact with an infected bat or other wild animal. Strict isolation of infected patients is essential to reduce onward ebolavirus transmission.
Publication info London :Bell and Daldy,1872.
Twenty-plume Moth (Alucita hexadactyla)
…a species of many-plumed moth (Alucitidae) which is native to parts of Europe, but has been introduced into North America. Like other members of its family A. hexadactyla does not have the typical two pairs of scaled wings other moths have, instead it has ~20 thin plumes (which are also lined with small scales). Adult A. hexadactlya can be seen flying throughout most, if not all, of the year. A. hexadactlya caterpillars feed almost exclusively on honeysukle (Lonicera spp.) and are leaf miners, which means they will tunnel inside the leaf to feed whilst avoiding predators.
Global late Quaternary [132,000 to 1,000 years ago] Megafauna Extinctions linked to humans, not climate change
Christopher Sandom, Søren Faurby, Brody Sandel and Jens-Christian Svenning (Department of Bioscience, Aarhus University, Denmark)
— Proceedings of the Royal Society / Biological Sciences, 22 July 2014
Abstract The late Quaternary megafauna extinction was a severe global-scale event. Two factors, climate change and modern humans, have received broad support as the primary drivers, but their absolute and relative importance remains controversial. …
We present, to our knowledge, the first global analysis of this extinction based on comprehensive country-level data on the geographical distribution of all large mammal species (more than or equal to 10 kg) that have gone globally or continentally extinct between the beginning of the Last Interglacial at 132 000 years BP and the late Holocene 1000 years BP, testing the relative roles played by glacial–interglacial climate change and humans.
We show that the severity of extinction is strongly tied to hominin palaeobiogeography, with at most a weak, Eurasia-specific link to climate change. …
IMAGE Global maps of late Quaternary [a, b] large mammal extinction severity, [c] hominin palaeobiogeography, [d] temperature anomaly and [e] precipitation velocity. [More detail here …]
Global late Quaternary megafauna extinctions linked to humans, not climate change is an open access article.
STRUCTURE OF CHIKUNGUNYA VIRUS-LIKE PARTICLES
Modeled Using X-ray Crystallography and Electron Cryo-microscopy
Chikungunya, a mosquito-borne virus discovered in 1955 by two scientists in Tanzania, has been a health problem in Africa and southern Asia for decades. It made its way to the Caribbean in late 2013.
Research article: Siyang Sun et al: “Structural analyses at pseudo atomic resolution of Chikungunya virus and antibodies show mechanisms of neutralization” || April 2, 2013 || eLife 2013;2:e00435 [an open access peer reviewed journal]
The Chikungunya virus is carried by mosquitos and can cause a number of diseases in humans including encephalitis, which can be fatal in some cases, and severe arthritis.
Chikungunya virus has a single-stranded RNA genome that codes for four non-structural proteins and five structural proteins. …
A recent mutation in the E1 protein of the virus has allowed it to efficiently reproduce in a different species of mosquitos, leading to a Chikungunya epidemic in Réunion Island in 2005 and the subsequent infection of millions of individuals in Africa and Asia. The virus [has already spread to] the Americas.
[Recently, researchers from Purdue University and several other US institutions, led by Siyang Sun] used two techniques – X-ray crystallography and electron cryo-microscopy – to determine the structure of Chikungunya virus-like particles, and to obtain new insights into the interactions of these particles with four related antibodies.
Electron cryo-microscopy was used to figure out the structure of the particles at near atomic resolution, and X-ray crystallography was used to determine the atomic resolution structures of two of the four Fab [fragment antigen-binding] antibodies that neutralize the Chikungunya virus.
Electron cryo-microscopy was also used to probe the complex formed by the interactions between the virus-like particles and the antibodies.
Continue reading at eLife…
TOP: Structure of the Chikungunya virion ||| BOTTOM: (A) Surface-shaded figure of ectodomain (left) and surface-shaded figure of nucleocapsid (right), colored according to the radial distance from the center of the virus. White triangles indicate one icosahedral asymmetric unit. (B) Cross-section of the virus showing density above 1.5 σ also colored according to the radial distance from the center of the virus. (C) Resolution of β-strands in the E1 [protein] domain III. [DOI: http://dx.doi.org/10.7554/eLife.00435.003]