-
aamukherjee A Slice of Entropie -
alchymista Alchymista -
crownedrose Fading Like A Dead Star -
expose-the-light Quarks to Quasars -
ikenbot CWL -
abluegirl A Blue Girl -
perscientiamlibertas A Matter of the Most Pleasant Fraternal Confidence
The Strange Beauty of Diatoms and Phytoplankton - Full Gallery
abluegirl
The EDGE of Existence - a web mapping application that allows users to explore the world’s most unique and endangered mammals and amphibians. This map was developed by the Evolutionarily Distinct and Globally Endangered (EDGE) project of the Zoological Society of London (ZSL), and it highlights regions of the world which should be priorities for conservation efforts. Read more at BBC, or try the application yourself.
Colorful phytoplankton blooms off the coast of France. Nasa writes:
Blooms can be a blessing to other marine species, as these tiny floating plants often feed everything from zooplankton to fish to whales. But some algae and plankton blooms can turn dangerous, either through the production of chemical toxins or by severely depleting the oxygen supply in the ocean and creating “dead zones” that suffocate marine creatures.
Influenza Virus | kat m research
This negative-stained transmission electron micrograph (TEM) depicts the ultrastructural details of an influenza virus particle, or “virion”. A member of the taxonomic family Orthomyxoviridae, the influenza virus is a single-stranded RNA organism
The Biological Clock by i-heart-histo
The ovaries at birth contain every oocyte/egg cell (and some extra) that a woman will ovulate during her entire reproductive lifetime. She literally carries all her eggs in two baskets. The older she gets, the longer those eggs have been hanging around in a type of stasis/partial division (Prophase I of meiosis). After the age of 30, every passing year brings with it a slightly increased risk of a chromosomal defect occurring in the ovulated oocyte, in particular Down’s syndrome.
And so…with the first ovulation at puberty, the biological clock starts ticking with amazing regularity until the eggs run dry at menopause.
During a typical 28 day cycle, fluctuating levels of pituitary hormones awake a number of oocytes from their lengthy hibernation and trigger the follicle in which they reside to commence maturation (folliculogenesis). Ultimately, on Day 14 of the cycle one of these oocyes is selected for ovulation and can be fertilized in the female reproductive tract where it will form a blastocyst.
The biological clock image, like the Seamless Gut, blends together the stages of folliculogenesis as if it they were occurring simultaneously in a single region of the ovary.
1. Primordial follicles
These cells contain a primary oocyte halted in Prophase I of meiosis. A rise in Follicle Stimulating Hormone levels from the anterior pituitary trigger a number of these to commence folliculogenesis. Histologically this type of follicle is surrounded by a layer of simple squamous follicular cells.
2. Primary follicles (unilaminar)These cells are growing follicles. The oocyte remains in Prophase I of meiosis. in the unilaminar stage the follicular cells form a ring of simple cuboidal cells.
3. Primary follicles (multilaminar)
The oocyte remains in Prophase I of meiosis but the follicular cells have proliferated to form a stratified layer of cells surrounding thee oocyte. This is called the stratum granulosum.
4. Secondary follicles
The oocyte remains in Prophase I of meiosis. However, the follicle continues growing and eventually the stratum granulosum cells begin to separate to form a fluid filled cyst called an antrum. The connective tissue surrounding the follicle thickens to form a theca interna and theca externa. These cells will eventually form a temporary endocrine organ after ovulation.
5. Tertiary/Graafian follicle
On Day 13 of the menstrual cycle, a surge in the pituitary hormones Leutinizing Hormone (LH) and Follicle Stimulating Hormone (FSH) trigger the oocyte in the dominant secondary follicle to complete the first meiotic division forming a secondary oocyte. This cell sits within a large tertiary follicle. The secondary oocyte is arrested in Metaphase II of the second meiotic division.
Ov = Ovulation
On Day 14 of the menstrual cycle, the tertiary follicle fuses with the surface of the ovary and the secondary oocyte is released into the uterine tube. The secondary oocyte will only complete meiosis if it is fertilized by a spermatozoon (sperm cell).
Don’t let those oocytes egg-spire!…tick, tock, tick, tock, tick, tock…
Cue an influx of as many egg based puns as you can possibly think of - so get cracking!
i-heart-histo
x
NIH: National Heart, Lung, and Blood Institute
neuromorphogenesisPulsing corals. Scientists hypothesize that the movement of the coral keeps oxygen from building up near by, improving the availability of carbon dioxide for the photosynthetic algae that the coral rely on. The pulsation also stirs the water to improve nutrient supplies. Only corals of the Xeniidae pulsate.
Read more about the study at Science News.
Cancer detection equipment shows us why some corals resist bleaching
Coral bleaching is a huge problem made worse by global warming. It threatens extremely productive ecosystems that are home to countless marine species. Yet some corals do better than others wen exposed to the same hostile environment. Why is that? Scientists at Northwestern University and the Field Museum of Natural History asked themselves that very question, and they think they found the answer using optical technology designed for early cancer detection.
The researchers discovered that reef-building corals scatter light in different ways to the symbiotic algae that feed the corals. Corals that are less efficient at light scattering retain algae better under stressful conditions and are more likely to survive. Corals whose skeletons scatter light most efficiently have an advantage under normal conditions, but they suffer the most damage when stressed.
The findings could help predict the response of coral reefs to the stress of increasing seawater temperatures and acidity, helping conservation scientists preserve coral reef health and high biodiversity. (source)
So the corals that were the “fittest” (in the natural selection meaning of the word) in the past are turning out to be disadvantaged compared to their less efficient cousins under today’s environment. This is the first research to show that light-scattering properties are a risk factor for corals. Hopefully this will help us devise ways to better protect coral reefs, as they are the most fertile biodiversity hotspots in our planet’s oceans.
The whole study was published under an open access license, so you can read it here.
Ricin: What is it?
Government officials in Washington have shut down mail delivery to the US Senate after detecting ricin in a letter addressed to Mississippi senator Roger Wicker, a Republican, on 16 April. Here are some facts about the toxin.
What is ricin?
According to the US Centers for Disease Control and Prevention (CDC), ricin is a poison found naturally in castor beans, and can be derived from the waste product, called ‘mash’, left over when castor beans are processed to make castor oil.
How deadly is ricin?
According to the CDC, ricin is “very toxic.” Data from tests in monkeys suggest that just 3 milligrams of inhaled ricin can kill an adult.
How does it work?
Ricin inactivates ribosomes, components responsible for manufacturing proteins within human cells. Cells stop making proteins essential to life and die.
What are the symptoms of ricing poisoning?
That depends on how ricin enters the body. Inhaled ricin can cause breathing difficulties, fever, cough and nausea. Ingested ricin can cause vomiting, diarrhea, dehydration, and seizures. Symptoms can appear as early as 4 hours and as late as 24 hours after exposure. Death can occur between three and six days after exposure.
How does one become exposed?
It’s possible to become poisoned with ricin by eating large quantities of castor beans or by ingesting the poison itself, but ricin is a more potent and deadly bioterror agent when inhaled as aerosol particles. Simply touching ricin is not likely to kill a person unless he or she ingests it from the skin.
Has ricin been used as an agent of warfare and bioterrorism?
Ricin has a long history as an agent of biological warfare1. The US War Department first considered using ricin in 1918 and worked with British scientists to develop a ricin bomb that appears never to have been used in combat. The US military experimented with inhalable ricin powders in the 1940s and the Iraqi military packed it into artillery shells in the 1980s. Ricin was most likely used to kill Bulgarian journalist Georgi Markov in Great Britain in 1978. Ricin was also detected in 2003 and 2004 in a South Carolina postal facility, in a mailroom serving the office of the US Senate’s then-majority leader Bill Frist, and in a letter sent to the White House, though it did not cause any illnesses or deaths in those cases. In the mid-1990s, members of a militia group, the Minnesota Patriots Council, were convicted of conspiring to kill law enforcement officials using ricin. It has also been found in the possession of suspected terrorist groups such as al Qaeda.
How is ricin detected?
Sensors at locations around the country, such as mail sorting facilities, check routinely for the presence of ricin and other pathogens. If a sample tests positive, it is transferred to a lab that performs follow-up tests using antibodies targeted to ricin proteins or DNA from the castor bean plant. In this instance,ricin was initially detectedat a Washington DC mail sorting facility and its presence was confirmed by a laboratory in Maryland.
Can ricin poisoning be treated?
There is no antidote to ricin toxin. One company, Soligenix of Princeton, New Jersey, is developing a vaccine against ricin, but it has only progressed through very early-stage clinical trials and has not been approved by the US Food and Drug Administration. It could theoretically be given to poisoning victims under an “emergency use authorization” that permits the use of unapproved treatments and vaccines if no alternative exists. However, the vaccine works by stimulating the body in advance of an attack to produce protective antibodies against ricin. Since the symptoms of ricin poisoning are irreversible four hours after exposure, the vaccine is not likely to help soon enough to save lives after the discovery of a ricin release. The US National Institute of Allergy and Infectious Diseases is funding research into drugs to treat ricin poisoning.
Giant snails on advance in Florida
Snails as large as rats are invading South Florida. Sure, they look adorable with their wiggling eye stalks, but like all destructive invasive species, they’re causing havoc not only in the Florida ecosystem, but in the lives of the people who live there. They can eat through plaster walls, consume vast quantities of the native vegetation, and the shells can puncture car tires. The snails have an unfortunate habit of leaving slime everywhere they go.
This problem is growing. An individual snail can produce 1200 eggs a year. They also carry a parasite that can cause illness in humans. Recently, experts gathered to determine the best way to eradicate the snails, including using bait designed to kill the snails, however that method could kill indigenous snails also.
You can read more about the snails at BBC news, and at gawker.com.
Lab-grown kidney’s transplanted into rats
In the past, scientists have been able to successfully grow simpler tissues, such as windpipes, but now, scientists at Massachusetts General Hospital in Boston have developed a procedure to grow a more complex organ in the lab: rat kidneys. They have done this by stripping away native cells for a donor kidney, leaving behind a scaffolding comprised of collagen, which is then repopulated with a recipient animal’s own stem cells.
Though testing hasn’t yet progressed to human-scale versions, the potential benefit of this is significant. if this approach can be used for humans, it would reduce the risk of organ rejection, and it would also provide a greater availability of organs for those patients in need.
You can read more about the technique used to engineer the kidney at this article on Nature.com by Ed Yong, and at New Scientist.
Thanks to Stanford University’s aptly named Clarity, scientists are now able to scan the brain for unobstructed views of neurons and their connections. In this scan, aided by a green fluorescent protein, one is able to see the axonal and dendritic branches of neurons within the hippocampus.
alchymista
Why Humidity Makes Your Hair Curl
If you have long hair, you probably don’t need to look up a weather report to get an idea of how much humidity’s in the air: You can simply grab a fistful of hair and see how it feels. Human hair is extremely sensitive to humidity—so much that some hygrometers (devices that indicate humidity) use a hair as the measuring mechanism, because it changes in length based on the amount of moisture in the air.
Straight hair goes wavy. If you have curly hair, humidity turns it frizzy or even curlier. Taming the frizz has become a mega industry, with different hair smoothing serums promising to “transform” and nourish hair “without weighing hair down.” But just why does humidity have this strange effect on human hair?
Hair’s chemical structure, it turns out, makes it unusually susceptible to changes in the amount of hydrogen present in the air, which is directly linked to humidity. Most of a hair’s bulk is made up of bundles of long keratin proteins, represented as the middle layer of black dotstightly packed together in the cross-section at right.
These keratin proteins can be chemically bonded together in two different ways. Molecules on neighboring keratin strands can form a disulfide bond, in which two sulfur atoms are covalently bonded together. This type of bond is permanent—it’s responsible for the hair’s strength—and isn’t affected by the level of humidity in the air.
But the other type of connection that can form between adjacent keratin proteins, a hydrogen bond, is much weaker and temporary, with hydrogen bonds breaking and new ones forming each time your hair gets wet and dries again. (This is the reason why, if your hair dries in one shape, it tends to remain in roughly that same shape over time.)
Hydrogen bonds occur when molecules on neighboring keratin strands each form a weak attraction with the same water molecule, thereby indirectly bonding the two keratin proteins together. Because humid air has much higher numbers of water molecules than dry air, a given strand of hair can form much higher numbers of hydrogen bonds on a humid day. When many such bonds are formed between the keratin proteins in a strand of hair, it causes the hair to fold back on itself at the molecular level at a greater rate.
On the macro level, this means that naturally curly hair as a whole becomes curlier or frizzier due to humidity. As an analogy, imagine the metal coil of a spring. If you straighten and dry your hair, it’ll be like the metal spring, completely straightened out into a rod. But if it’s a humid day, and your hair is prone to curling, water molecules will steadily be absorbed and incorporated into hydrogen bonds, inevitably pulling the metal rod back into a coiled shape.
Scientists can now turn brains invisible
Say hello to the stunning results of CLARITY — a new technique that enables scientists to turn brain matter and other tissues completely transparent. It’s already being hailed as one of the most important advances for neuroanatomy in decades, and it’s not hard to see why.
Cut off a mouse’s head. Carefully remove its brain, wash it gently, and you’ll wind up with something resembling the sample pictured above, on the left. Grey matter, it so happens, lives up to its name. Due in large part to molecules known as lipids, organs like the brain are usually opaque. Lipids comprise cell membranes and provide structural support to a variety of organs and tissues throughout the body – but they also scatter light. As a result, most microscopes are lucky if they can peer even a millimeter into biological matter before images in the viewfinder get blurry.
One of the more popular techniques scientists use to get around this hangup is called “sectioning.” It’s brutally straightforward in practice: a researcher will freeze a chunk of tissue (a mouse brain, for example) in liquid nitrogen, and then slice it into scores of little sheets, each one just a fraction of a millimeter thick. This turns a single 3-dimensional problem (otherwise inscrutable, due to its non-transparent nature) into a series of 2-dimensional ones. Go through a brain layer by layer, and you can cobble together a volumetric picture of everything from cellular structure, to the spatial distribution of proteins, to the various connections that form between neurons. But the tradeoff is substantial. You’re literally cutting your sample into a bunch of tiny little pieces. With every slice, tissue is deformed, connections are severed, information is lost.
CLARITY does away with the slicing and dicing entirely. The technique, described in the latest issue of Nature by a team led by Stanford researchers Kwanghun Chung and Karl Deisseroth, works by stripping away all of a tissue’s light-scattering lipids, while leaving everything else right where it belongs. You’ll recall, however, that lipids play an important structural role in organs like the brain; if you remove them, everything else falls apart — a fact that has plagued past attempts at making tissues see-through. But that’s where CLARITY is different.
CLARITY works by virtue of a bait and switch. In their study, Chung and Deisseroth submerge a mouse brain in a mixture of formaldehyde and acrylamide. The former attaches important cellular structures and components to the latter, which solidifies into a gel when heated. An electrical current is then coursed through the gel, stripping it of anything not hanging on. The lipids go bye-bye, and the brain goes clear as Jell-O. More importantly: all of its significant structures remain intact and in place. Neurons, synapses, proteins, DNA. Every last component is exactly where it should be.
The ability to strip a brain of its lipids and nothing else gives rise to remarkable research possibilities. In the image above, a mouse brain turned transparent with CLARITY has been made visible again by labeling specific neurons with a fluorescent marker that glows green. Researchers have been using this technique (called “immunolabeling”) to highlight certain molecular and structural features for years, but with CLARITY, labeled cells can be seen in three dimensions, all at once.
In fact, the process of removing the brain’s lipids actually makes the tissues more permeable, making it easier to not only tag them with fluorescent markers in the first place, but untagthem and then tag them again with an entirely different label. What’s more, the fact that you don’t have to cut a brain up to see how it was stained means that you can add more tags to the same brain. The picture below shows a region of the brain known as the hippocampus that has had its different neurons labeled in a variety of fluorescent colors. A brain that was once impermeable to light has been made invisible, only to be made visible again – but this time with remarkable specificity.
There’s nothing that says this technique couldn’t be used on human brains, so long as you have the time. Coloring-in a clarified brain like the one above requires soaking it in solution with the fluorescent labels you want to tag it with. For a mouse brain, that can take a month or more. For a brain as voluminous as a human’s, it would take much longer. (While Chung and Deisseroth did demonstrate their technique could be used on human brains, they did so with a small block of tissue, not an entire brain.)
Likewise, there’s nothing that says CLARITY could not be used on tissues besides the brain, though the organ certainly shows the most immediate promise. The ability to visualize the neuronal connections throughout a transparent brain, for example, could spur incredible growth in the field of connectomics, which seeks to map the brain’s neuronal wiring. In neuroscience, few tools are as coveted as those that enable you to see the part and the whole simultaneously – CLARITY could enable researchers to study the structure and distribution of individual neurons in the context of the whole brain. “This is the kind of innovation that will slingshot neuroscience far beyond today,” said Henry Markram, leader of Europe’s recently unveiled Human Brain Project, in an interview with NatGeo’s Ed Yong. “This new method of whole-brain imaging across all levels of the brain provides a way to acquire much of the key data we will need.”
(via abluegirl)
