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Lipid droplets as endogenous intracellular microlenses – newsconcerns

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An optically trapped lipid droplet inside an adipose cell focuses the excitation light and collects the fluorescent signals from the cytoskeleton to form a magnified fluorescence image. Credit: Xixi Chen, Tianli Wu, Zhiyong Gong, Jinghui Guo, Xiaoshuai Liu, Yao Zhang, Yuchao Li, Pietro Ferraro, and Baojun Li

With the demand in real-time monitoring of endoplasmic variations and rapid detection of extracellular signals, a great number of approaches to bioimaging have been developed. The past few decades have witnessed a dramatic progress in optical imaging, especially with the emerging of microsphere-assisted techniques that have the excellent ability of signal collection and enable real-time and super-resolution imaging with conventional optical microscopic systems. However, as most of the microspheres in current strategies are in solid and artificially synthetic materials, they are of very low biocompatibility. Fortunately, lessons from nature have shown that some bio-components and already-existing objects can interact with light and are able to take the same functions as the real optical elements.

In a paper newly published in Light Science & Application, a team of researchers, led by Professors Baojun Li, Yao Zhang and Yuchao Li from Institute of Nanophotonics, Jinan University, China and Dr. Pietro Ferraro from CNR-ISASI, Institute of Applied Sciences and Intelligent Systems, Italy, demonstrate that lipid droplets, dynamic structures that naturally exist in cells, can act as intracellular microlenses for real-time monitoring of subcellular structures and detection of extracellular signals. With a spherical shape and a refractive index higher than cytoplasm and periplasm, the lipid droplets exhibit the lensing effect to efficiently converge both the excitation light and the fluorescence signals.

Lipid droplets as endogenous intracellular microlenses
(a) Fluorescence images of the microfilaments (F-actin filaments) of a living adipose cell. The weak fluorescent signals (a1) were efficiently enhanced by the lipid droplet (diameter: 7.7 μm) (a2). (b) Fluorescence images of the microfilaments in a fixed adipose cell with an 18.6-μm lipid droplet. (c) Fluorescence and bright-field images of the lysosomes in a living adipose cell with an 11.3-μm lipid droplet. (d) Fluorescence and bright-field images of the adenoviruses in a living adipose cell with an 8.1-μm lipid droplet, the blue lines represent the movement trajectory of the adenoviruses in 10 min. The fluorescence images were focused on the surfaces of the cells (b1) and the virtual image planes (b2, c1 and d1) formed by the lipid droplets. The bright-field image was focused on the virtual image plane formed by the lipid droplet (c2 and d2). Credit: Xixi Chen, Tianli Wu, Zhiyong Gong, Jinghui Guo, Xiaoshuai Liu, Yao Zhang, Yuchao Li, Pietro Ferraro, and Baojun Li

To achieve intracellular imaging of subcellular structures, the lipidic microlenses work in a contact mode in which the collection efficiency of the emitted fluorescent signals is greatly increased by the lipid droplets. As a result, the required excitation power in fluorescence imaging can be reduced by up to 73%. Driven by scanning optical tweezers, the lipid droplets can be moved inside the cell to perform an enhanced intracellular fluorescence imaging of the microfilaments, lysosomes and adenoviruses in living cells. Moreover, due to the refractive index contrast of the lipid droplets to cytoplasm, the long focal length of the lipid droplets can extend the fluorescence enhancement strategies to a non-contact mode that increases the working distance of imaging and detection by the lipidic microlenses. In the non-contact mode, the excitation light is highly converged by the lipid droplets to enhance the fluorescence intensity from the extracellular environment surrounding the cells. In the experiments, an efficient detecting of fluorescent signals of cancer cells in extracellular fluid was accomplished by the lipidic microlenses.

Lipid droplets as endogenous intracellular microlenses
(a) Schematic (side view) of the enhanced detection of cancer cells in fluid by a lipid droplet inside the adipose cell: the lipid droplet acts as a biolens by focusing excitation light into the cancer cell and improving the collection of fluorescent signals at same time. (b) Fluorescence images (top view) of the detecting process. The yellow and red dotted circles indicate the lipid droplet (diameter: 20 μm) and the cancer cell, respectively. The mitochondria of the cancer cell were marked by Mito-Tracker (green). The red arrow indicates the direction of fluid flow in the capillary. Credit: Xixi Chen, Tianli Wu, Zhiyong Gong, Jinghui Guo, Xiaoshuai Liu, Yao Zhang, Yuchao Li, Pietro Ferraro, and Baojun Li

The presented lensing effect of the lipid droplets is expected to find applications with fully biocompatible miniaturized tools for biosensing, endoscopic analysis and single-cell diagnosis. The use of the lipid droplets as intracellular microlenses also provides opportunities to design and construct diverse endogenous photonic devices.


Biophotonic probes for bio-detection and imaging


More information:
Xixi Chen et al, Lipid droplets as endogenous intracellular microlenses, Light: Science & Applications (2021). DOI: 10.1038/s41377-021-00687-3
Provided by
Chinese Academy of Sciences

Citation:
Lipid droplets as endogenous intracellular microlenses (2021, December 27)
retrieved 27 December 2021
from https://phys.org/news/2021-12-lipid-droplets-endogenous-intracellular-microlenses.html

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Consistent Asteroid Collisions Rock Previous Thinking on Mars Impact Craters – SciTechDaily

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This image provides a perspective view of a triple crater in the ancient Martian highlands. Credit: ESA/DLR/FU Berlin

New Curtin University research has confirmed the frequency of asteroid collisions that formed impact craters on <span aria-describedby="tt" class="glossaryLink" data-cmtooltip="

Mars
Mars is the second smallest planet in our solar system and the fourth planet from the sun. Iron oxide is prevalent in Mars’ surface resulting in its reddish color and its nickname "The Red Planet." Mars’ name comes from the Roman god of war.

“>Mars has been consistent over the past 600 million years.

New Curtin University research has confirmed the frequency of asteroid collisions that formed impact craters on Mars has been consistent over the past 600 million years.

The study, published in Earth and Planetary Science Letters, analyzed the formation of more than 500 large Martian craters using a crater detection algorithm previously developed at Curtin, which automatically counts the visible impact craters from a high-resolution image.

Despite previous studies suggesting spikes in the frequency of asteroid collisions, lead researcher Dr. Anthony Lagain, from Curtin’s School of Earth and Planetary Sciences, said his research had found they did not vary much at all for many millions of years.

Impact Craters on Mars

One of the 521 large craters that has been dated in the study. The formation age of this 40km crater has been estimated using the number of small craters accumulated around it since the impact occurred. A portion of these small craters are shown on the right panel and all of them have been detected using the algorithm. In total, more than 1.2 million craters were used to date the Martian craters. Credit: Curtin University

Dr. Lagain said counting impact craters on a planetary surface was the only way to accurately date geological events, such as canyons, rivers, and volcanoes, and to predict when, and how big, future collisions would be.

“On Earth, the erosion of plate tectonics erases the history of our planet. Studying planetary bodies of our Solar System that still conserve their early geological history, such as Mars, helps us to understand the evolution of our planet,” Dr. Lagain said.

“The crater detection algorithm provides us with a thorough understanding of the formation of impact craters including their size and quantity, and the timing and frequency of the asteroid collisions that made them.”

Past studies had suggested that there was a spike in the timing and frequency of asteroid collisions due to the production of debris, Dr. Lagain said.

“When big bodies smash into each other, they break into pieces or debris, which is thought to have an effect on the creation of impact craters,” Dr. Lagain said.

“Our study shows it is unlikely that debris resulted in any changes to the formation of impact craters on planetary surfaces.”

Co-author and leader of the team that created the algorithm, Professor Gretchen Benedix, said the algorithm could also be adapted to work on other planetary surfaces, including the Moon.

“The formation of thousands of lunar craters can now be dated automatically, and their formation frequency analyzed at a higher resolution to investigate their evolution,” Professor Benedix said.

“This will provide us with valuable information that could have future practical applications in nature preservation and agriculture, such as the detection of bushfires and classifying land use.”

Reference: “Has the impact flux of small and large asteroids varied through time on Mars, the Earth and the Moon?” by Anthony Lagain, Mikhail Kreslavsky, David Baratoux, Yebo Liu, Hadrien Devillepoix, Philip Bland, Gretchen K. Benedix, Luc S. Doucet and Konstantinos Servis, 7 January 2022, Earth and Planetary Science Letters.
DOI: 10.1016/j.epsl.2021.117362

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B.C. researchers uncover mechanism that keeps large whales from drowning while feeding on krill – CTV News Vancouver

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Vancouver –

New research from the University of British Columbia is shedding light on the ways that whales feed underwater without flooding their airways with seawater.

The research, published this month in Current Biology, shows that lunge-feeding whales – the type that lunge and gulp at large schools of krill – have a special mechanism in the back of their mouths that stops water from entering their lungs when eating.

“It’s kind of like when a human’s uvula moves backwards to block our nasal passages, and our windpipe closes up while swallowing food,” says lead author Dr. Kelsey Gil, a postdoctoral researcher in the department of zoology, in a statement.

Specifically, a fleshy bulb acts as a plug, to close off upper airways, while a larynx closes to block lower airways.

The humpback whale and the blue whale are both lunge-feeders, but the scientists’ research focused on fin whales, thanks in part to being able to travel to Iceland in 2018 and examine carcass remains at a commercial whaling station.

“We haven’t seen this protective mechanism in any other animals, or in the literature. A lot of our knowledge about whales and dolphins comes from toothed whales, which have completely separated respiratory tracts, so similar assumptions have been made about lunge-feeding whales,” Gil said.

Lunge-feeders are impressive, Gil said, because sometimes the amount of food and water they consume is larger than their bodies. After snapping at krill, and while blocking the water from their airways, the whales then drain the ocean water through their baleen, leaving behind the tasty fish.

The study’s senior author Dr. Robert Shadwick, a professor in the UBC department of zoology, says the efficiency of the whales’ feeding is a key factor in their evolution.

“Bulk filter-feeding on krill swarms is highly efficient and the only way to provide the massive amount of energy needed to support such a large body size. This would not be possible without the special anatomical features we have described,” he said in a statement. 

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Study confirmed the frequency of asteroid collisions that formed Mars craters – Tech Explorist

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Mapping and counting impact craters are the most commonly used technique to derive detailed insights on geological events and processes shaping the surface of terrestrial planets. Scientists from Curtin University have used a crater detection algorithm to analyze the formation of more than 500 large Martian craters.

The algorithm they used automatically counts the visible impact craters from a high-resolution image. Scientists found that the frequency of asteroid collisions that formed Mars craters has been consistent for over 600 million years.

Lead scientist Dr. Anthony Lagain from Curtin’s School of Earth and Planetary Sciences said, “Despite previous studies suggesting spikes in the frequency of asteroid collisions, this research had found they did not vary much at all for many millions of years.”

“Counting impact craters on a planetary surface was the only way to accurately date geological events, such as canyons, rivers, and volcanoes, and to predict when, and how big, future collisions would be.”

“On Earth, the erosion of plate tectonics erases the history of our planet. Studying planetary bodies of our Solar System that still conserve their early geological history, such as Mars, helps us to understand the evolution of our planet.”

“The crater detection algorithm provides us with a thorough understanding of the formation of impact craters, including their size and quantity, and the timing and frequency of the asteroid collisions that made them.”

“Past studies had suggested that there was a spike in the timing and frequency of asteroid collisions due to the production of debris.”

“When big bodies smash into each other, they break into pieces of debris, which is thought to affect the creation of impact craters.”

“Our study shows it is unlikely that debris resulted in any changes to the formation of impact craters on planetary surfaces.”

Co-author and leader of the team that created the algorithm, Professor Gretchen Benedix, said“the algorithm could also be adapted to work on other planetary surfaces, including the Moon.”

“The formation of thousands of lunar craters can now be dated automatically, and their formation frequency analyzed at a higher resolution to investigate their evolution.”

“This will provide us with valuable information that could have future practical applications in nature preservation and agriculture, such as the detection of bushfires and classifying land use.”

Journal Reference:

  1. Anthony Lagain et al. Has the impact flux of small and large asteroids varied through time on Mars, the Earth, and the Moon? DOI: 10.1016/j.epsl.2021.117362

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