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I found this strange bur on a stray cat in my neighborhood. I've never seen anything like it, and Google reverse image search thinks it's an earring. Found in in northern California, just south of Clearlake. (38.90 N, 122.60 W)
The spike structure is almost exactly one inch long.
A friend has informed me this is from the redstem Filaree, and there are some cool time-lapse videos on Youtube of their spinning behavior when they are exposed to water, which is thought to help them burrow into the soil. (I'm just glad it didn't get a chance to burrow into the kitty!)
Scientists identify protein that activates plant response to nitrogen deficiency
Nitrates are critical for the growth of plants, so plants have evolved sophisticated mechanisms to ensure sufficient nitrate uptake from their environments. In a new study published in Nature Plants, researchers at Nagoya University, Japan, have identified a plant enzyme that is key to activating a nitrate uptake mechanism in response to nitrogen starvation. This finding explains how plants meet their needs in challenging environments, opening doors to improving agriculture in such environments.
When nitrate levels are plentiful in a plant's environment, a plant can achieve adequate nitrate uptake levels by relying on what plant biologists call a "low-affinity transport system." But when nitrates become scarce in a plant's local environment, it may need to switch to a more powerful nitrate uptake mechanism known as a "high-affinity transport system." In Arabidopsis plants, which frequently serve as model organisms for plant biology research, the NRT2.1 protein plays an important role in the high-affinity transport system. Interestingly, when Arabidopsis plants synthesize the NRT2.1 protein, they initially produce an inactive protein that can later be activated when the high-affinity transport system is needed.
This synthesis of a nonfunctioning protein that can later be activated intrigued Dr. Yoshikatsu Matsubayashi of Nagoya University, but he sees a certain logic in this preparatory protein synthesis he notes, "Proteins cannot be synthesized when the nitrogen deficiency occurs." In other words, plants need to synthesize the proteins in a high-affinity transport system before a nitrogen deficiency necessitates the use of those proteins, because nitrogen deficiency itself makes it difficult to synthesize new proteins. In order to better understand this remarkable system, Dr. Matsubayashi and his colleagues set out to identify the protein that activates NRT2.1 in response to nitrogen starvation.
Previous studies had shown that a peptide called CEP found in plant roots plays an important role in activating biochemical pathways that respond to nitrogen starvation, so the researchers focused their investigation on the CEP and its downstream CEPD pathway. Their experiments soon drew their attention to a protein called At4g32950. The researchers found that this protein responds to nitrogen starvation by activating the NRT2.1 protein. It achieves this activation by removing a phosphate group from a specific location on the NRT2.1 protein, so the investigators decided to give the At4g32950 protein a new name: CEPD-induced phosphatase, or "CEPH" for short.
CEPH is found mainly in the cells close to the surface of the Arabidopsis plant's roots, which is an optimal location for activating a system that evolved for rapid nitrate uptake from the environment. As expected, using laboratory methods to inactivate the gene that encodes CEPH impaired the ability of Arabidopsis plants to use the high-affinity transport system for rapid nitrate uptake, and this meant that the modified plants had lower internal nitrate levels and grew to smaller sizes.
Collectively, these results indicate that CEPH plays a critical role in responding to nitrogen starvation through its activation of the NRT2.1 protein. Dr. Matsubayashi sees considerable potential utility in CEPH as a genetic engineering tool, as he notes, "Artificially enhancing CEPH activity could enable scientists to create plants that grow even in soils with low nutrient levels." Such findings could change the way agriculture and food security are handled.
Astronauts Identify Mystery Microbes in Space for the 1st Time
NASA astronauts successfully sequenced the DNA of microbes found aboard the International Space Station, marking the first time unknown organisms were sequenced and identified entirely in space. The astronauts found the mystery microbes were two commonly associated with the human microbiome.
Previously, microbes had to be sent to Earth for analysis, and this new sequencing marks an important step in diagnosing astronaut illnesses and, someday, identifying any DNA-based life found on other planets, NASA officials said in a statement. Researchers back on Earth have now verified the microbe identifications are correct, marking the experiment a success.
As a part of the Genes in Space-3 mission, astronauts on the space station last year touched a petri plate to surfaces on the space station and grew the bacteria found there into colonies, which NASA astronaut Peggy Whitson used to amplify and then sequence their DNA. In July 2016, NASA astronaut Kate Rubins became the first to sequence DNA in space, but this latest experiment was both the first time cells were transferred for analysis and the first time unknown organisms were identified in space. (Rubins used mouse DNA sent from Earth.) [In Photos: Record-Breaking NASA Astronaut Peggy Whitson]
As Whitson led the space station experiment, she was guided by NASA microbiologist Sarah Wallace and her team at Johnson Space Center in Houston. But at a critical time, as Whitson prepared to sequence the DNA, Hurricane Harvey intervened.
"We started hearing the reports of Hurricane Harvey the week in between Peggy performing the first part of collecting the sample and gearing up for the actual sequencing," Wallace said in the statement. Ultimately, the Payload Operations Integration Center at NASA's Marshall Space Flight Center in Huntsville, Alabama, helped to connect Whitson and Wallace through Wallace's personal phone, and she guided Whitson to sequence the DNA before sending the data back to Houston.
During analysis, "Right away, we saw one microorganism pop up, and then a second one, and they were things that we find all the time on the space station," Wallace said. "The validation of these results would be when we got the sample back to test on Earth."
Whitson and the samples traveled back to Earth in September 2017, when the next phase of the Genes in Space-3 mission began. Scientists sequenced the microbes again on Earth and verified that each had been identified correctly.
NASA spokesperson Dan Huot told Space.com that of the three colonies grown and then sequenced on the space station, one ended up being Staphylococcus capitis and two were Staphylococcus hominis.
Before this experiment, astronauts had amplified DNA for analysis on the space station using a device called the miniPCR thermal cycler, and they had sequenced a DNA sample with the so-called MinION device. But at last, they had successfully combined the two, NASA officials said.
"It was a natural collaboration to put these two pieces of technology together, because individually, they're both great," Wallace said, "but together, they enable extremely powerful molecular biology applications."
Editor's Note: This article was updated Jan. 3 with further information on the microbes.
One of the best ways to learn is to play. We have a collection of activities that let you learn biology by playing. You can try a biology experiment or test your knowledge with one of the biology puzzles based on our stories. There are printable and online coloring pages and worksheets that you can use to practice your coloring skills.
Wait, there's more. The Bird Finder tool can help you identify that mystery bird in your backyard. You can also venture into Body Depot where you can learn about your body and the biology that keeps it going. With so many activities you might find it hard to choose, so don't. You can try them all.
The Flashlight Mystery.
Like a crime detective, you can use the elements of the scientific method to find the answer to everyday problems. For example you pick up a flashlight and turn it on, but the light does not work. You have observed that the light does not work. You ask the question, Why doesn't it work? With what you already know about flashlights, you might guess (hypothesize) that the batteries are dead. You say to yourself, if I buy new batteries and replace the old ones in the flashlight, the light should work. To test this prediction you replace the old batteries with new ones from the store. You click the switch on. Does the flashlight work? No?
What else could be the answer? You go back and hypothesize that it might be a broken light bulb. Your new prediction is if you replace the broken light bulb the flashlight will work. It’s time to go back to the store and buy a new light bulb. Now you test this new hypothesis and prediction by replacing the bulb in the flashlight. You flip the switch again. The flashlight lights up. Success!
If this were a scientific project, you would also have written down the results of your tests and a conclusion of your experiments. The results of only the light bulb hypothesis stood up to the test, and we had to reject the battery hypothesis. You would also communicate what you learned to others with a published report, article, or scientific paper.
Re: Week 5
1 - TTAA, TTAa, TtAA, TtAa. - Izzie (pickles) is right because the question doesn't specify whether or not the plant is homozygous/heterozygous for either of the alleles.
2 - I would cross it with a homozygous recessive plant, because if any recessive traits (terminal or short) are expressed in the offspring of the cross then that would mean the mystery plant also had the recessive allele for that trait.
3 - i)TTAAxttaa ii)TTAaxttaa iii)TtAAxttaa iv)TtAaxttaa
i - TtAa
ii - TtAa, Ttaa
iii - TtAa, ttAa
iv - TtAa, ttAa, Ttaa, ttaa
This is not 'performing a cross' because more than one gene is involved.
4 - Because people are having children later and later, late-acting dominant lethal alleles in the population as a whole may start to be more commonly expressed. However, because the allele IS lethal, that would mean the children born with it would end up dying earlier - which would have a negative impact on the population.
Scientists identify properties that allow proteins to strengthen under pressure
In a simulated actin network, actin filaments are randomly oriented before pressure application (left) but align after pressure application (right), altering the network's material properties. Credit: Scheff et al
A new rubber band stretches, but then snaps back into its original shape and size. Stretched again, it does the same. But what if the rubber band was made of a material that remembered how it had been stretched? Just as our bones strengthen in response to impact, medical implants or prosthetics composed of such a material could adjust to environmental pressures such as those encountered in strenuous exercise.
A research team at the University of Chicago is now exploring the properties of a material found in cells that allows cells to remember and respond to environmental pressure. In a paper published on May 14, 2021 in Soft Matter, they teased out secrets for how it works—and how it could someday form the basis for making useful materials.
Protein strands, called actin filaments, act as bones within a cell, and a separate family of proteins called cross-linkers hold these bones together into a cellular skeleton. The study found that an optimal concentration of cross-linkers, which bind and unbind to permit the actin to rearrange under pressure, allows this skeletal scaffolding to remember and respond to past experience. This material memory is called hysteresis.
"Our findings show that the properties of actin networks can be changed by how filaments are aligned," said Danielle Scheff, a graduate student in the Department of Physics who conducted the research in the lab of Margaret Gardel, Horace B. Horton Professor of Physics and Molecular Engineering, the James Franck Institute, and the Institute of Biophysical Dynamics. "The material adapts to stress by becoming stronger."
To understand how the composition of this cellular scaffolding determines its hysteresis, Scheff mixed up a buffer containing actin, isolated from rabbit muscle, and cross-linkers, isolated from bacteria. She then applied pressure to the solution, using an instrument called a rheometer. If stretched in one direction, the cross-linkers allowed the actin filaments to rearrange, strengthening against subsequent pressure in the same direction.
To see how hysteresis depended on the solution's consistency, she mixed different concentrations of cross-linkers into the buffer.
Surprisingly, these experiments indicated that hysteresis was most pronounced at an optimal cross-linker concentration solutions exhibited increased hysteresis as she added more cross-linkers, but past this optimal point, the effect again became less pronounced.
"I remember being in lab the first time I plotted that relationship and thinking something must be wrong, running down to the rheometer to do more experiments to double-check," Scheff said.
To better understand the structural changes, Steven Redford, a graduate student in Biophysical Sciences in the labs of Gardel and Aaron Dinner, Professor of Chemistry, the James Franck Institute, and the Institute for Biophysical Dynamics, created a computational simulation of the protein mixture Scheff produced in the lab. In this computational rendition, Redford wielded a more systematic control over variables than possible in the lab. By varying the stability of bonds between actin and its cross-linkers, Redford showed that unbinding allows actin filaments to rearrange under pressure, aligning with the applied strain, while binding stabilizes the new alignment, providing the tissue a "memory" of this pressure. Together, these simulations demonstrated that impermanent connections between the proteins enable hysteresis.
"People think of cells as very complicated, with a lot of chemical feedback. But this is a stripped-down system where you can really understand what is possible," said Gardel.
The team expects these findings, established in a material isolated from biological systems, to generalize to other materials. For example, using impermanent cross-linkers to bind polymer filaments could allow them to rearrange as actin filaments do, and thus produce synthetic materials capable of hysteresis.
"If you understand how natural materials adapt, you can carry it over to synthetic materials," said Dinner.
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To Solve 3 Cold Cases, This Small County Got a DNA Crash Course
Forensic genealogy helped nab the Golden State Killer in 2018. Now investigators across the country are using it to revisit hundreds of unsolved crimes.
Watch the video below for more information on the resolution of a cold case nearly 40 years in the making.
Major funding is provided by a generous donation from audiochuck
What pH Tells You
A solution's pH will be a number between 0 and 14. A solution with a pH of 7 is classified as neutral. If the pH is lower than 7, the solution is acidic. When pH is higher than 7, the solution is basic. These numbers describe the concentration of hydrogen ions in the solution and increase on a negative logarithmic scale. For example, If Solution A has a pH of 3 and Solution B has a pH of 1, then Solution B has 100 times as many hydrogen ions than A and is therefore 100 times more acidic.
Researchers identify role of interneurons in food-seeking behavior of worms
Credit: Pixabay/CC0 Public Domain
As anyone who has ever procrastinated knows, remembering that you need to do something and acting on that knowledge are two different things. To understand how learning changes nerve cells and leads to different behaviors, researchers studied the much simpler nervous system of worms.
"In this study, we can now translate neuronal activity to behavioral response," said project researcher Hirofumi Sato, a neuroscientist at the University of Tokyo and first author of the research paper recently published in Cell Reports.
The discovery was made possible using technology that researchers describe as a "robot microscope," first developed in 2019 by researchers at Tohoku University in Miyagi Prefecture, northeastern Japan.
The technique involves genetically modifying the worms to add fluorescent tags onto specific molecules. The microscope then detects and tracks the fluorescent light as a worm crawls around, meaning researchers can watch chemical signals travel through and between individual neurons in awake, unrestrained animals.
The worms used in research studies, C. elegans, don't eat pure salt, but researchers can train worms to associate high or low salt levels in their environment with food. When transferred to any new environment, trained worms will begin searching for food using salt levels as a clue about which direction they should go. For example, if worms learned to expect food in high-salt areas but they notice that salt levels are decreasing as they travel, the worms will stop and change directions to try to find a higher salt level. With additional training, worms can also learn the opposite food-salt level association.
Neuroplasticity, or the brain's ability to change and "rewire" neurons, is essential for any learned behavior. The mystery for the scientific community is how different environmental clues (high or low salt) can lead to the same physical behavior (stop and change direction).
Researchers at the University of Tokyo studied worms to understand the neuroplasticity of learning. Three views of the same recording show a worm starting in an area of higher salt concentration, moving towards a lower salt concentration, stopping, and then changing directions to go back towards the higher-salt area. The dark circles are pillars in the container that act like speed bumps, slowing down the worm so the microscope can track its movements. Note how the GcaMP6s signal (middle) becomes brighter when the worm reverses direction. Left: C. elegans viewed under normal white light with a square drawn around the neurons examined in the research. Middle: Fluorescent light view of genetically encoded GCaMP6s, an indicator that a neuron is sending a signal to another neuron. Right: Fluorescent light view of mCherry, a fluorescent tag added to the same neuron as GcaMP6s. Credit: Project Researcher Hirofumi Sato, CC BY 4.0
"Many animals show this flexible learned behavior pattern, so we want to understand the mechanism," said Sato.
This type of behavior requires a sensory neuron (which detects salt), motor neurons (which control movement) and interneurons (which communicate between the other two types). Although C. elegans only have 302 neurons in their entire 1-centimeter-long bodies, these same types of neurons exist in humans and communicate using the same signal molecule.
Specifically, that signal molecule is glutamate, widely recognized as one of the brain's most important signaling molecules.
"We know that if there is a defect in glutamate signaling, that might cause Alzheimer's disease or other neuronal diseases," said Sato.
The UTokyo team's new data found two different types of glutamate receptors on the same interneuron are involved in the worms' behavior. Both inhibitory and excitatory glutamate receptors responded in the same pattern, but at different intensities based on whether the worms had learned to seek high or low salt concentrations.
The exact mechanism controlling the motor neuron's signals to the interneuron's glutamate receptors remains unclear. However, this is one of the first documentations of glutamate signaling between sensory and interneurons showing experience-dependent plasticity.
Future research will continue to investigate exactly how the sensory neuron and interneuron communicate.