Contradictiontonature - Sapere Aude

Leopard shark makes world-first switch from sexual to asexual reproduction

A leopard shark in an Australian aquarium has reproduced asexually after being separated from her mate.

It is the first reported case of a shark switching from sexual to asexual or parthenogenetic reproduction and only the third reported case among all vertebrate species.

The leopard shark, Leonie, was captured in the wild in 1999 and introduced to a male shark at the Reef HQ aquarium in Townsville, Queensland, in 2006. Leopard sharks are also known as zebra sharks.

One of the baby sharks born to leopard sharks at Reef HQ aquarium in Townsville, who have produced live young through asexual reproduction. Photograph: Tourism and Events Queensland

Leonie, the world’s first shark known to have switched from sexual to asexual reproduction, at Reef HQ aquarium in Townsville. Photograph: Tourism and Events Queensland

Quote from #JaneGoodall primatologist and anthropologist. More quotes like this to inspire you in my new journal I Love Science, in stores March but ready for preorder now! #womeninscience #ilovescience #anthropology #scientificliteracy

Scientists discover new arsenic-based broad-spectrum antibiotic

"We are running out of tools to fight these diseases. We need a new potent antibiotic to solve this problem," says Yoshinaga, the other co-senior author. "We showed that this new novel arsenic compound can be a potent antibiotic,"

Antibiotic resistance has been called one of the biggest public health threats of our time. There is a pressing need for new and novel antibiotics to combat the rise in antibiotic-resistant bacteria worldwide.

Researchers from Florida International University’s Herbert Wertheim College of Medicine are part of an international team that has discovered a new broad-spectrum antibiotic that contains arsenic. The study, published in Nature’s Communication Biology, is a collaboration between Barry P. Rosen, Masafumi Yoshinaga, Venkadesh Sarkarai Nadar and others from the Department of Cellular Biology and Pharmacology, and Satoru Ishikawa and Masato Kuramata from the Institute for Agro-Environmental Sciences, NARO in Japan.

“The antibiotic, arsinothricin or AST, is a natural product made by soil bacteria and is effective against many types of bacteria, which is what broad-spectrum means,” said Rosen, co-senior author of the study published in the Nature journal, Communications Biology. “Arsinothricin is the first and only known natural arsenic-containing antibiotic, and we have great hopes for it.”

Although it contains arsenic, researchers say they tested AST toxicity on human blood cells and reported that “it doesn’t kill human cells in tissue culture.”

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I gotta split! Image of the Week - June 22, 2015

CIL:41466 - http://www.cellimagelibrary.org/images/41466

Description: Confocal image of a mitotic spindle in a dividing cell. The spindle is shown in yellow and the surrounding actin cytoskeleton is in blue. Sixth Prize, 2007 Olympus BioScapes Digital Imaging Competition.

Authors: Patricia Wadsworth and the 2007 Olympus Bioscapes Digital Imaging Competition®.

Licensing: Attribution Non-Commercial No Derivatives: This image is licensed under a Creative Commons Attribution, Non-Commercial, No Derivatives License

Original illustrations from the 1851 edition of the Iconographic Encyclopedia of Science, Literature and Art by J.G. Heck.

This illustrator’s new book is a clever introduction to women scientists through history.

During a dinnertime discussion two years ago, illustrator Rachel Ignotofsky and her friend started chewing on the subject of what’s become a meaty conversation in America: women’s representation in STEM fields.

Ignotofsky, who lives in Kansas City, Missouri, lamented that kids don’t seem to hear much about women scientists. “I just kept saying over and over and over again that we’re not taught the stories of these women when we’re in school,” she recalls. Eventually, it dawned on her: “I was saying it enough that I was like, you know, I’m just talking a lot about this; I should draw some of the women in science that I feel really excited about.”

Learn more here.

[Reprinted with permission from Women in Science Copyright ©2016 by Rachel Ignotofsky. Published by Ten Speed Press, an imprint of Penguin Random House LLC.]

Next week I’ll give a presentation on the Researchers Night at Eötvös Loránd University, Hungary with the title: “Chemistry of light and the light of chemistry”.

During this presentation one of my favorite dyes will be also presented: Nile Red. However, just as usual, the 1000 USD/gram price was a bit over our budget, so I had to make it.

The raw product was contaminated with a few impurities, but a fast purification, by simple filtering the mixture through a short column helped a lot and ended up with a +95% pure product.

At first I concentrated the product from a dilute solution on the column as seen on the first pics. It’s interesting to see, that it has a different fluorescence in solution (faint orange fluorescent)  and while it’s absorbed on the solid phase (pink, highly fluorescent).

After all the product was on the solid phase, I added another solvent and washed down the pure, HIGHLY FLUORESCENT product. Everything else, what was mainly products of side reactions, stuck at the top of the column as seen on the second pics and the gifs.

Also here is a video from the whole process in HD: https://youtu.be/W0Lk5jkd_B0

Image of the Week – February 13, 2017

CIL:40984 - http://www.cellimagelibrary.org/images/40984

Description: Montage image of a brain stem from a Brainbow transgenic mouse. In Brainbow mice, neurons randomly choose combinations of red, yellow and cyan fluorescent proteins, so that they each glow a particular color. This provides a way to distinguish neighboring neurons and visualize brain circuits. These are large caliber axons of the auditory pathway. First Prize, 2007 Olympus BioScapes Digital Imaging Competition. For additional details see: Livet J, Weissman TA, Kang H, Draft RW, Lu J, Bennis RA, Sanes JR, Lichtman JW. Nature. 2007 Nov 1;450(7166):56-62.

Authors: Jean Livet and the 2007 Olympus BioScapes Digital Imaging Competition®

Licensing: Attribution Non-Commercial No Derivatives: This image is licensed under a Creative Commons Attribution, Non-Commercial, No Derivatives License

Building blocks of memories seen in brains for the first time

Observations of hundreds of neurons in mice suggest that we may divide our memories of where we’ve been into small chunks of experience

At last, we’ve seen what might be the primary building blocks of memories lighting up in the brains of mice.

We have cells in our brains – and so do rodents – that keep track of our location and the distances we’ve travelled. These neurons are also known to fire in sequence when a rat is resting, as if the animal is mentally retracing its path – a process that probably helps memories form, says Rosa Cossart at the Institut de Neurobiologie de la Méditerranée in Marseille, France.

But without a way of mapping the activity of a large number of these individual neurons, the pattern that these replaying neurons form in the brain has been unclear. Researchers have suspected for decades that the cells might fire together in small groups, but nobody could really look at them, says Cossart.

To get a look, Cossart and her team added a fluorescent protein to the neurons of four mice. This protein fluoresces the most when calcium ions flood into a cell – a sign that a neuron is actively firing. The team used this fluorescence to map neuron activity much more widely than previous techniques, using implanted electrodes, have been able to do.

Observing the activity of more than 1000 neurons per mouse, the team watched what happened when mice walked on a treadmill or stood still.

As expected, when the mice were running, the neurons that trace how far the animal has travelled fired in a sequential pattern, keeping track.

These same cells also lit up while the mice were resting, but in a strange pattern. As they reflected on their memories, the neurons fired in the same sequence as they had when the animals were running, but much faster. And rather than firing in turn individually, they fired together in sequential blocks that corresponded to particular fragments of a mouse’s run.

“We’ve been able to image the individual building-blocks of memory,” Cossart says, each one reflecting a chunk of the original episode that the mouse experienced.

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