How elephant nose
fish switch between electrical, visual sense
Source: University of Bonn
Summary: The elephant nose fish explores objects in its surroundings
by using its eyes or its electrical sense -- sometimes both together.
Zoologists have now found out how complex the processing of these sensory
impressions is. With its tiny brain, the fish achieves performance
comparable to that of humans or mammals.
Gerhard von der
Emde and Sarah Schumacher are from the Institute of Zoology at University of
Bonn. Credit: Photo by Barbara Frommann/Uni Bonn
The elephant nose fish explores objects in its surroundings by using its
eyes or its electrical sense -- sometimes both together. Zoologists at the
University of Bonn and a colleague from Oxford have now found out how
complex the processing of these sensory impressions is. With its tiny brain,
the fish achieves performance comparable to that of humans or mammals. The
advance results have been published online in the Proceedings of the
National Academy of Sciences.
The elephant nose fish (Gnathonemus petersii) is widespread in the flowing
waters of West Africa and hunts insect larva at dawn and dusk. It is helped
by an electrical organ in its tail, which emits electrical impulses. The
skin contains numerous sensor organs that perceive objects in the water by
means of the changed electrical field. "This is a case of active
electrolocation, in principle the same as the active echolocation of bats,
which use ultrasound to perceive a three-dimensional image of their
environment," says Professor Dr. Gerhard von der Emde at the Institute of
Zoology at the University of Bonn. Furthermore, the elephant nose fish can
also orient using its eyes.
Professor von der Emde, along with his doctoral candidate Sarah Schumacher
and Dr. Theresa Burt de Perera of Oxford University, have now investigated
how the unusual fish processes the information from the various sensory
channels. Ms. Schumacher summarizes the results: "The animals normally use
both senses. If necessary, for example because one of the two senses
provides no information or the information of the two senses differs
greatly, however, the fish can switch back and forth between their visual
and electrical senses." The scientists were surprised by the manner in which
the fish use these two senses to get the best perception of their
environment: When the animals became familiar with an object in the
aquarium, for example with the visual sense, they were also able to
recognize it again using the electrical sense, although they had never
perceived it electrically before.
Fish give precedence to the most reliable sensory information.
In addition, the fish demonstrated a previously unexpected ability: Their
brain gave more weight to the information it thought was more reliable. When
the two senses delivered different information in the close range of up to
two centimeters, the fish trusted only the electrical information and were
then "blind" to the visual stimuli. In contrast, for more distant objects,
the animals relied above all on their eyes. They perceived the environment
best by using their visual and electrical senses in combination. "A transfer
between the different senses was previously known only for certain highly
developed mammals, such as monkeys, dolphins, rats, and humans," says
Professor von der Emde. An example: In a dark, unfamiliar apartment, people
feel their way forward to avoid stumbling. When the light goes on, the
obstacles felt are recognized by the eye without any problem. Mammals
process such information with their cerebral cortex. The elephant nose fish,
however, has just a relatively small brain and no cerebral cortex at all --
but nevertheless switches back and forth between the senses.
Clever experimental setup
The scientists came up with a very clever test setup: The elephant nose fish
was in an aquarium. Separated from it were two different chambers, between
which the animal could choose. Behind openings to the chambers there were
differently shaped objects: a sphere or a cuboid. The fish learned to steer
toward one of these objects by being rewarded with insect larvae.
Subsequently, it searched for this object again, to obtain the reward again.
When does the fish use a particular sense? In order to answer this question,
the researchers repeated the experiments in absolute darkness. Now the fish
could rely only on its electrical sense. As shown by images taken with an
infrared camera, it was able to recognize the object only at short
distances. With the light on the fish was most successful, because it was
able to use its eyes and the electrical sense for the different distances.
In order to find out when the fish used its eyes alone, the researchers made
the objects invisible to the electrical sense. Now, the sphere and cuboid to
be discriminated had the same electrical characteristics as the water.
Many repetitions of the individual experiments were necessary in order to
apply statistical analyses to reach conclusions about the sensory processing
of the elephant nose fish. The scientists worked with a total of ten
animals, working more or less in shifts. "The behavior of the different
individuals was nearly identical," says Professor von der Emde. For that
reason the scientists are certain that this enormous sensory performance is
achieved not only by a particularly talented specimen but by all elephant
The above post is reprinted from materials provided by University of Bonn.
Sarah Schumacher, Theresa Burt de Perera, Johanna Thenert, Gerhard von der
Emde. Cross-modal object recognition and dynamic weighting of sensory inputs
in a fish. Proceedings of the National Academy of Sciences, 2016; 201603120
Nano scientists develop the 'ultimate discovery tool'
Rapid discovery power is similar to what gene chips offer biology
Source: Northwestern University
Summary: The discovery power of the gene chip is coming to
nanotechnology. Researchers have figured out how to make combinatorial
libraries of nanoparticles in a very controlled way. Some of the
nanoparticle compositions have never been observed before on Earth. The tool
they are developing could be used to rapidly test millions to billions of
different nanoparticles at one time to zero in on the best particle for a
specific use. Applications include catalysts, light-harvesting materials,
pharmaceuticals and optoelectronic devices.
library of polyelemental nanoparticles was developed using Dip-Pen
Nanolithography. This novel nanoparticle library opens up a new field of
nanocombinatorics for rapid screening of nanomaterials for a multitude of
properties. Credit: Peng-Cheng Chen/James Hedrick
The discovery power of the gene chip is coming to nanotechnology. A
Northwestern University research team is developing a tool to rapidly test
millions and perhaps even billions or more different nanoparticles at one
time to zero in on the best particle for a specific use.
When materials are miniaturized, their properties -- optical, structural,
electrical, mechanical and chemical -- change, offering new possibilities.
But determining what nanoparticle size and composition are best for a given
application, such as catalysts, biodiagnostic labels, pharmaceuticals and
electronic devices, is a daunting task.
"As scientists, we've only just begun to investigate what materials can be
made on the nanoscale," said Northwestern's Chad A. Mirkin, a world leader
in nanotechnology research and its application, who led the study.
"Screening a million potentially useful nanoparticles, for example, could
take several lifetimes. Once optimized, our tool will enable researchers to
pick the winner much faster than conventional methods. We have the ultimate
Using a Northwestern technique that deposits materials on a surface, Mirkin
and his team figured out how to make combinatorial libraries of
nanoparticles in a very controlled way. (A combinatorial library is a
collection of systematically varied structures encoded at specific sites on
a surface.) Their study will be published June 24 by the journal Science.
The nanoparticle libraries are much like a gene chip, Mirkin says, where
thousands of different spots of DNA are used to identify the presence of a
disease or toxin. Thousands of reactions can be done simultaneously,
providing results in just a few hours. Similarly, Mirkin and his team's
libraries will enable scientists to rapidly make and screen millions to
billions of nanoparticles of different compositions and sizes for desirable
physical and chemical properties.
"The ability to make libraries of nanoparticles will open a new field of
nanocombinatorics, where size -- on a scale that matters -- and composition
become tunable parameters," Mirkin said. "This is a powerful approach to
Mirkin is the George B. Rathmann Professor of Chemistry in the Weinberg
College of Arts and Sciences and founding director of Northwestern's
International Institute for Nanotechnology.
"I liken our combinatorial nanopatterning approach to providing a broad
palette of bold colors to an artist who previously had been working with a
handful of dull and pale black, white and grey pastels," said co-author
Vinayak P. Dravid, the Abraham Harris Professor of Materials Science and
Engineering in the McCormick School of Engineering.
Using five metallic elements -- gold, silver, cobalt, copper and nickel --
Mirkin and his team developed an array of unique structures by varying every
elemental combination. In previous work, the researchers had shown that
particle diameter also can be varied deliberately on the 1- to 100-nanometer
Some of the compositions can be found in nature, but more than half of them
have never existed before on Earth. And when pictured using high-powered
imaging techniques, the nanoparticles appear like an array of colorful
Easter eggs, each compositional element contributing to the palette.
To build the combinatorial libraries, Mirkin and his team used Dip-Pen
Nanolithography, a technique developed at Northwestern in 1999, to deposit
onto a surface individual polymer "dots," each loaded with different metal
salts of interest. The researchers then heated the polymer dots, reducing
the salts to metal atoms and forming a single nanoparticle. The size of the
polymer dot can be varied to change the size of the final nanoparticle.
This control of both size and composition of nanoparticles is very
important, Mirkin stressed. Having demonstrated control, the researchers
used the tool to systematically generate a library of 31 nanostructures
using the five different metals.
To help analyze the complex elemental compositions and size/shape of the
nanoparticles down to the sub-nanometer scale, the team turned to Dravid,
Mirkin's longtime friend and collaborator. Dravid, founding director of
Northwestern's NUANCE Center, contributed his expertise and the advanced
electron microscopes of NUANCE to spatially map the compositional
trajectories of the combinatorial nanoparticles.
Now, scientists can begin to study these nanoparticles as well as build
other useful combinatorial libraries consisting of billions of structures
that subtly differ in size and composition. These structures may become the
next materials that power fuel cells, efficiently harvest solar energy and
convert it into useful fuels, and catalyze reactions that take low-value
feedstocks from the petroleum industry and turn them into high-value
products useful in the chemical and pharmaceutical industries.
The above post is reprinted from materials provided by Northwestern
University. The original item was written by Megan Fellman.
Peng-Cheng Chen, Xiaolong Liu, James L. Hedrick, Zhuang Xie, Shunzhi Wang,
Qing-Yuan Lin, Mark C. Hersam, Vinayak P. Dravid, Chad A. Mirkin.
Polyelemental nanoparticle libraries. Science, 2016 DOI:
Probing giant planets' dark hydrogen
Source: Carnegie Institution for Science
Summary: Hydrogen is the most-abundant element in the universe, but
there is still so much we have to learn about it. One of the biggest
unknowns is its transformation under the extreme pressures and temperatures
found in the interiors of giant planets, where it is squeezed until it
becomes liquid metal, capable of conducting electricity. New work measures
the conditions under which hydrogen undergoes this transition in the lab and
finds an intermediate 'dark hydrogen' state.
of the layer of dark hydrogen the team's lab mimicry indicates would be
found beneath the surface of gas giant planets like Jupiter, courtesy of
Stewart McWilliams. Credit: University of Edinburgh (graphics) and NASA
Hydrogen is the most-abundant element in the universe. It's also the
simplest--sporting only a single electron in each atom. But that simplicity
is deceptive, because there is still so much we have to learn about
One of the biggest unknowns is its transformation under the extreme
pressures and temperatures found in the interiors of giant planets, where it
is squeezed until it becomes liquid metal, capable of conducting
electricity. New work published in Physical Review Letters by Carnegie's
Alexander Goncharov and University of Edinburgh's Stewart McWilliams
measures the conditions under which hydrogen undergoes this transition in
the lab and finds an intermediate state between gas and metal, which they're
calling "dark hydrogen."
On the surface of giant planets like Jupiter, hydrogen is a gas. But between
this gaseous surface and the liquid metal hydrogen in the planet's core lies
a layer of dark hydrogen, according to findings gleaned from the team's lab
Using a laser-heated diamond anvil cell to create the conditions likely to
be found in gas giant planetary interiors, the team probed the physics of
hydrogen under a range of pressures from 10,000 to 1.5 million times normal
atmospheric pressure and up to 10,000 degrees Fahrenheit.
They discovered this unexpected intermediate phase, which does not reflect
or transmit visible light, but does transmit infrared radiation, or heat.
"This observation would explain how heat can easily escape from gas giant
planets like Saturn," explained Goncharov.
They also found that this intermediate dark hydrogen is somewhat metallic,
meaning it can conduct an electric current, albeit poorly. This means that
it could play a role in the process by which churning metallic hydrogen in
gas giant planetary cores produces a magnetic field around these bodies, in
the same way that the motion of liquid iron in Earth's core created and
sustains our own magnetic field.
"This dark hydrogen layer was unexpected and inconsistent with what modeling
research had led us to believe about the change from hydrogen gas to
metallic hydrogen inside of celestial objects," Goncharov added.
The above post is reprinted from materials provided by Carnegie Institution
R. Stewart McWilliams, D. Allen Dalton, Mohammad F. Mahmood, Alexander F.
Goncharov. Optical Properties of Fluid Hydrogen at the Transition to a
Conducting State. Physical Review Letters, 2016; 116 (25) DOI:
Fix for 3-billion-year-old genetic error could dramatically improve
Source: University of Texas at Austin
Summary: Researchers found a fix for a 3-billion-year-old glitch in
one of the major carriers of information needed for life, RNA, which until
now produced errors when making copies of genetic information. The discovery
will increase precision in genetic research and could dramatically improve
medicine based on a person's genetic makeup.
bioscientist Jared Ellefson of the University of Texas at Austin has created
a way for RNA to "proofread" copies of genetic information for the first
time. This artist's interpretation of the process shows RNA making DNA
copies in a droplet of water. Credit: Jared Ellefson, University of Texas at
For 3 billion years, one of the major carriers of information needed for
life, RNA, has had a glitch that creates errors when making copies of
genetic information. Researchers at The University of Texas at Austin have
developed a fix that allows RNA to accurately proofread for the first time.
The new discovery, published June 23 in the journal Science, will increase
precision in genetic research and could dramatically improve medicine based
on a person's genetic makeup.
Certain viruses called retroviruses can cause RNA to make copies of DNA, a
process called reverse transcription. This process is notoriously prone to
errors because an evolutionary ancestor of all viruses never had the ability
to accurately copy genetic material.
The new innovation engineered at UT Austin is an enzyme that performs
reverse transcription but can also "proofread," or check its work while
copying genetic code. The enzyme allows, for the first time, for large
amounts of RNA information to be copied with near perfect accuracy.
"We created a new group of enzymes that can read the genetic information
inside living cells with unprecedented accuracy," says Jared Ellefson, a
postdoctoral fellow in UT Austin's Center for Systems and Synthetic Biology.
"Overlooked by evolution, our enzyme can correct errors while copying RNA."
Reverse transcription is mainly associated with retroviruses such as HIV. In
nature, these viruses' inability to copy DNA accurately may have helped
create variety in species over time, contributing to the complexity of life
as we know it.
Since discovering reverse transcription, scientists have used it to better
understand genetic information related to inheritable diseases and other
aspects of human health. Still, the error-prone nature of existing RNA
sequencing is a problem for scientists.
"With proofreading, our new enzyme increases precision and fidelity of RNA
sequencing," says Ellefson. "Without the ability to faithfully read RNA, we
cannot accurately determine the inner workings of cells. These errors can
lead to misleading data in the research lab and potential misdiagnosis in
the clinical lab."
Ellefson and the team of researchers engineered the new enzyme using
directed evolution to train a high-fidelity (proofreading) DNA polymerase to
use RNA templates. The new enzyme, called RTX, retains the highly accurate
and efficient proofreading function, while copying RNA. Accuracy is improved
at least threefold, and it may be up to 10 times as accurate. This new
enzyme could enhance the methods used to read RNA from cells.
"As we move towards an age of personalized medicine where everyone's
transcripts will be read out almost as easily as taking a pulse, the
accuracy of the sequence information will become increasingly important,"
said Andy Ellington, a professor of molecular biosciences. "The significance
of this is that we can now also copy large amounts of RNA information found
in modern genomes, in the form of the RNA transcripts that encode almost
every aspect of our physiology. This means that diagnoses made based on
genomic information are far more likely to be accurate. "
In addition to Ellefson and Ellington, authors include Jimmy Gollihar,
Raghav Shroff, Haridha Shivram and Vishwanath Iyer. All are affiliated with
the Department of Molecular Biosciences at The University of Texas at
This research was supported by grants from the Defense Advanced Research
Projects Agency, National Security Science and Engineering Faculty Fellows,
NASA and the Welch Foundation. A provisional patent was filed on the new
sequence of the enzyme.
The above post is reprinted from materials provided by University of Texas
Jared W. Ellefson, Jimmy Gollihar, Raghav Shroff, Haridha Shivram,
Vishwanath R. Iyer, Andrew D. Ellington. Synthetic evolutionary origin of a
proofreading reverse transcriptase. Science, 2016; 352 (6293): 1590-1593 DOI:
Human brain houses diverse populations of neurons, new research shows
Source: University of California - San Diego
Summary: A team of researchers has developed the first scalable
method to identify different subtypes of neurons in the human brain. The
research lays the groundwork for 'mapping' the gene activity in the human
brain and could help provide a better understanding of brain functions and
disorders, including Alzheimer's, Parkinson's, schizophrenia and depression.
identified 16 neuronal subtypes by analyzing thousands of individual neurons
in six Brodmann areas of a post mortem human brain. (Stock image) Credit: ©
BillionPhotos.com / Fotolia
A team of researchers has developed the first scalable method to identify
different subtypes of neurons in the human brain. The research lays the
groundwork for "mapping" the gene activity in the human brain and could help
provide a better understanding of brain functions and disorders, including
Alzheimer's, Parkinson's, schizophrenia and depression.
By isolating and analyzing the nuclei of individual human brain cells,
researchers identified 16 neuronal subtypes in the cerebral cortex -- the
brain's outer layer of neural tissue responsible for cognitive functions
including memory, attention and decision making. The team, led by
researchers at the University of California San Diego, The Scripps Research
Institute (TSRI) and Illumina, published their findings in the June 24
online issue of the journal Science.
"We're providing a unified framework to look at and compare individual
neurons, which can help us find out how many unique types of neurons exist,"
said Kun Zhang, bioengineering professor at the University of California,
San Diego and a corresponding author of the study.
Researchers can use these different neuronal subtypes to build what Zhang
calls a "reference map" of the human brain -- a foundation to understand the
differences between a healthy brain and a diseased brain.
"In the future, patients with brain disorders or abnormalities could be
diagnosed and treated based on how they differ from the reference map. This
is analogous to what's being done with the reference human genome map,"
The new study reflects a growing understanding that individual brain cells
are unique: they express different types of genes and perform different
functions. To better understand this diversity, researchers analyzed more
than 3,200 single human neurons in six Brodmann areas, which are regions of
the cerebral cortex classified by their functions and arrangements of
Through an interdisciplinary collaborative effort, the team developed a new
method to isolate and sequence individual cell nuclei. TSRI researchers led
by neuroscience professor Jerold Chun obtained the samples from a post
mortem brain and focused on isolating the neuronal nuclei. Zhang's lab
worked with Fluidigm, a manufacturer of microfluidic chips for single-cell
studies, to develop a protocol to identify and quantify RNA molecules in
individual neuronal nuclei. Scientists at San Diego-based Illumina sequenced
the resulting RNA libraries. Researchers led by biochemistry professor Wei
Wang at UC San Diego developed algorithms to cluster and identify 16
neuronal subtypes from the sequenced datasets.
Researchers deciphered what types of genes were "turned on" within each
nucleus and revealed that various combinations of the 16 subtypes tended to
cluster in cortical layers and Brodmann areas, helping explain why these
regions look and function differently.
Neurons exhibited many differences in their transcriptomic profiles -- the
patterns of genes that are being actively expressed by these cells --
revealing single neurons with shared, as well as unique, characteristics
that likely lead to difference in cellular function.
"We're finding new ways to understand the basic building blocks of the
brain," said Blue Lake, a postdoctoral researcher in Zhang's lab and a
co-first author of the study. "Our study opens the door to look at global
gene expression patterns and how that defines cell types within a normal
tissue, which can also be used to see what's abnormal in terms of disease or
In future studies, researchers aim to analyze neurons in other Brodmann
areas of the brain and investigate what subtypes exist in other brain
regions. They also plan to study neurons from multiple post mortem human
brains (this study only involved one) to investigate neuronal diversity
The above post is reprinted from materials provided by University of
California - San Diego. Note: Materials may be edited for content and
Kun Zhang et al. Neuronal subtypes and diversity revealed by single-nucleus
RNA sequencing of the human brain. Science, June 2016 DOI:
'Flower Power': Photovoltaic cells replicate rose petals
Source: (Karlsruhe Institute of Technology
Summary: With a surface resembling that of plants, solar cells
improve light-harvesting and thus generate more power. Scientists reproduced
the epidermal cells of rose petals that have particularly good
antireflection properties and integrated the transparent replicas into an
organic solar cell. This resulted in a relative efficiency gain of twelve
the epidermis of a rose petal is replicated in a transparent layer which is
then integrated into the front of a solar cell. Credit: Illustration:
Guillaume Gomard, KIT
With a surface resembling that of plants, solar cells improve
light-harvesting and thus generate more power. Scientists of KIT (Karlsruhe
Institute of Technology) reproduced the epidermal cells of rose petals that
have particularly good antireflection properties and integrated the
transparent replicas into an organic solar cell. This resulted in a relative
efficiency gain of twelve percent. An article on this subject has been
published recently in the Advanced Optical Materials journal.
Photovoltaics works in a similar way as the photosynthesis of plants. Light
energy is absorbed and converted into a different form of energy. In this
process, it is important to use a possibly large portion of the sun's light
spectrum and to trap the light from various incidence angles as the angle
changes with the sun's position. Plants have this capability as a result of
a long evolution process -- reason enough for photovoltaics researchers to
look closely at nature when developing solar cells with a broad absorption
spectrum and a high incidence angle tolerance.
Scientists at the KIT and the ZSW (Center for Solar Energy and Hydrogen
Research Baden-Württemberg) now suggest in their article published in the
Advanced Optical Materials journal to replicate the outermost tissue of the
petals of higher plants, the so-called epidermis, in a transparent layer and
integrate that layer into the front of solar cells in order to increase
First, the researchers at the Light Technology Institute (LTI), the
Institute of Microstructure Technology (IMT), the Institute of Applied
Physics (APH), and the Zoological Institute (ZOO) of KIT as well as their
colleagues from the ZSW investigated the optical properties, and above all,
the antireflection effect of the epidermal cells of different plant species.
These properties are particularly pronounced in rose petals where they
provide stronger color contrasts and thus increase the chance of
pollination. As the scientists found out under the electron microscope, the
epidermis of rose petals consists of a disorganized arrangement of densely
packed microstructures, with additional ribs formed by randomly positioned
In order to exactly replicate the structure of these epidermal cells over a
larger area, the scientists transferred it to a mold made of
polydimethylsiloxane, a silicon-based polymer, pressed the resulting
negative structure into optical glue which was finally left to cure under UV
light. "This easy and cost-effective method creates microstructures of a
depth and density that are hardly achievable with artificial techniques,"
says Dr. Guillaume Gomard, Group Leader "Nanopothonics" at KIT's LTI.
The scientists then integrated the transparent replica of the rose petal
epidermis into an organic solar cell. This resulted in power conversion
efficiency gains of twelve percent for vertically incident light. At very
shallow incidence angles, the efficiency gain was even higher. The
scientists attribute this gain primarily to the excellent omnidirectional
antireflection properties of the replicated epidermis that is able to reduce
surface reflection to a value below five percent, even for a light incidence
angle of nearly 80 degrees. In addition, as examinations using a confocal
laser microscope showed, every single replicated epidermal cell works as a
microlense. The microlense effect extends the optical path within the solar
cell, enhances the light-matter-interaction, and increases the probability
that the photons will be absorbed.
"Our method is applicable to both other plant species and other PV
technologies," Guillaume Gomard explains. "Since the surfaces of plants have
multifunctional properties, it might be possible in the future to apply
multiple of these properties in a single step." The results of this research
lead to another basic question: What is the role of disorganization in
complex photonic structures? Further studies are now examining this issue
with the perspective that the next generation of solar cells might benefit
from their results.
The above post is reprinted from materials provided by (Karlsruhe Institute
Ruben Hünig, Adrian Mertens, Moritz Stephan, Alexander Schulz, Benjamin
Richter, Michael Hetterich, Michael Powalla, Uli Lemmer, Alexander Colsmann,
Guillaume Gomard. Flower Power: Exploiting Plants' Epidermal Structures for
Enhanced Light Harvesting in Thin-Film Solar Cells. Advanced Optical
Materials, 2016; DOI: 10.1002/adom.201600046.
Eating air, making fuel
Scientists engineer bacteria to create sugar from the greenhouse gas carbon
Source: Weizmann Institute of Science
Summary: Is it possible to "reprogram" an organism that is found
higher in the food chain, which consumes sugar and releases carbon dioxide,
so that it will consume carbon dioxide from the environment and produce the
sugars it needs to build its body mass? Scientists now report that they have
engineered bacteria to create sugar from the greenhouse gas carbon dioxide.
Institute scientists engineer bacteria to create sugar from the greenhouse
gas carbon dioxide. Credit: Weizmann Institute of Science
All life on the planet relies, in one way or another, on a process called
carbon fixation: the ability of plants, algae and certain bacteria to "pump"
carbon dioxide (CO2) from the environment, add solar or other energy and
turn it into the sugars that are the required starting point needed for life
processes. At the top of the food chain are different organisms (some of
which think, mistakenly, that they are "more advanced") that use the
opposite means of survival: they eat sugars (made by photosynthetic plants
and microorganisms) and then release carbon dioxide into the atmosphere.
This means of growth is called "heterotrophism." Humans are, of course,
heterotrophs in the biological sense because the food they consume
originates from the carbon fixation processes of nonhuman producers.
Is it possible to "reprogram" an organism that is found higher in the food
chain, which consumes sugar and releases carbon dioxide, so that it will
consume carbon dioxide from the environment and produce the sugars it needs
to build its body mass? That is just what a group of Weizmann Institute of
Science researchers recently did. Dr. Niv Antonovsky, who led this research
in Prof. Ron Milo's lab at the Institute's Plant and Environmental Sciences
Department, says that the ability to improve carbon fixation is crucial for
our ability to cope with future challenges, such as the need to supply food
to a growing population on shrinking land resources while using less fossil
The Institute scientists rose to this challenge by inserting the metabolic
pathway for carbon fixation and sugar production (the so called Calvin
cycle) into the bacterium E. coli, a known "consumer" organism that eats
sugar and releases carbon dioxide.
The metabolic pathway for carbon fixation is well known, and Milo and his
group reckoned that, with proper planning, they would be able to attach the
genes containing the information for building it into the bacterium's
genome. Yet the main enzyme used in plants to fix carbon, RuBisCO, utilizes
as a substrate for the CO2 fixation reaction a metabolite which is toxic for
the bacterial cells. Thus the design had to include precisely regulating the
expression levels of the various genes across this multistep pathway.
In one way the team's well-thought-out plan was a resounding success: The
bacteria did indeed produce the carbon fixation enzymes, and these were
functional. But the machinery, as a whole, did not "deliver the goods." Even
though the carbon fixation machinery was expressed, the bacteria failed to
use CO2 for sugar synthesis, relying instead on an external supply of sugar.
"Of course, we were dealing with an organism that has evolved over millions
of years to eat sugar, not CO2," says Antonovsky. "So we turned to evolution
to help us create the system we intended."
Antonovsky, Milo and the team, including Shmuel Gleizer, Arren Bar-Even,
Yehudit Zohar, Elad Herz and others, next designed tanks called "chemostats,"
in which they grew the bacteria, gradually nudging them into developing an
appetite for CO2. Initially, along with ample bubbles of CO2, the bacteria
in the tanks were offered a large amount of pyruvate, which is an energy
source, as well as barely enough sugar to survive. Thus, by changing the
conditions of their environment and stressing them, the scientists forced
the bacteria to learn, by adaptation and development, to use the more
abundant material in their environment. A month went by, and things remained
fairly static. The bacteria seemed to not "get the hint." But at around a
month and a half, some bacteria showed signs of doing more than "just
surviving." By the third month the scientists were able to wean the evolved
bacteria from the sugar and raise them on CO2 and pyruvate alone. Isotope
labeling of the carbon dioxide molecules revealed that the bacteria were
indeed using CO2 to create a significant portion of their body mass,
including all the sugars needed to make the cell.
When the scientists sequenced the genomes of the evolved bacteria, they
found many changes scattered throughout the bacterial chromosomes. "They
were completely different from what we had predicted," says Milo. "It took
us two years of hard work to understand which of these are essential and to
unravel the 'logic' involved in their evolution." Repeating the experiment
(and again waiting months) gave the scientists essential clues for
identifying the mutations necessary for changing the E. coli diet from one
based on sugar to one using carbon dioxide.
Milo said, "The ability to program or reengineer E. coli to fix carbon could
give researchers a new toolbox for studying and improving this basic
process." Although currently the bacteria release CO2 back into the
atmosphere, the team envisions that in the future their insights might be
applied to creating microorganisms that soak up atmospheric CO2 and convert
it into stored energy or to achieving crops with carbon fixing pathways,
resulting in higher yields and better adaption to feeding humanity.
The above post is reprinted from materials provided by Weizmann Institute of
Niv Antonovsky et al. Sugar Synthesis from CO2 in Escherichia coli. Cell,
June 2016 DOI: 10.1016/j.cell.2016.05.064.
Researchers offer new theory on how climate affects violence.
life strategies, time orientation, self-control
Source: Ohio State University
Summary: Researchers have long struggled to explain why some violent
crime rates are higher near the equator than other parts of the world. Now,
a team of researchers has developed a model that could help explain why.
Aggression Model suggests hot temperatures make people uncomfortable and
irritated, which makes them more aggressive.Credit: © malven / Fotolia
Researchers have long struggled to explain why some violent crime rates are
higher near the equator than other parts of the world. Now, a team of
researchers have developed a model that could help explain why.
This new model goes beyond the simple fact that hotter temperatures seem to
be linked to more aggressive behavior.
The researchers believe that hot climates and less variation in seasonal
temperatures leads to a faster life strategy, less focus on the future, and
less self-control -- all of which contribute to more aggression and
"Climate shapes how people live, it affects the culture in ways that we
don't think about in our daily lives," said Brad Bushman, co-author of the
study and professor of communication and psychology at The Ohio State
Paul van Lange, lead author of the study and a professor of psychology at
the Vrije Universiteit Amsterdam (VU) added, "We believe our model can help
explain the impact of climate on rates of violence in different parts of the
The researchers, which included Maria I. Rinderu of VU, call the new model
CLASH (CLimate Aggression, and Self-control in Humans). They describe the
CLASH model in an online article in the journal Behavioral and Brain
Many studies have shown that levels of violence and aggression are higher in
hot climates, according to the researchers.
"But the two leading explanations of why that is so aren't satisfactory,"
The General Aggression Model (which Bushman helped develop) suggests hot
temperatures make people uncomfortable and irritated, which makes them more
aggressive. "But that doesn't explain more extreme acts, such as murder," he
Another explanation (Routine Activity Theory) is that people are outdoors
and interacting more with others when the weather is warm, which leads to
more opportunities for conflict. But that doesn't explain why there's more
violence when the temperature is 95 degrees F (35 °C) than when it is 75
degrees F (24 °C) -- even though people might be outside under both
The CLASH model states that it is not just hotter temperatures that lead to
more violence -- it is also climates that have less seasonal variation in
"Less variation in temperature, combined with heat, brings some measure of
consistency to daily life," Rinderu said.
That means there is less need to plan for large swings between warm and cold
weather. The result is a faster life strategy that isn't as concerned about
the future and leads to less need for self-control.
"Strong seasonal variation in temperature affects culture in powerful ways.
Planning in agriculture, hoarding, or simply preparing for cold winters
shapes the culture in many ways, often with people not even noticing it. But
it does shape how much a culture values time and self-control," Van Lange
"If there is less variation, you're freer to do what you want now, because
you're not preparing foods or chopping firewood or making winter clothes to
get you through the winter. You also may be more concerned with the
immediate stress that comes along with parasites and other risks of hot
climates, such as venomous animals."
People living in these climates are oriented to the present rather than the
future and have a fast life strategy -- they do things now.
"We see evidence of a faster life strategy in hotter climates with less
temperature variation -- they are less strict about time, they have less use
of birth control, they have children earlier and more often," Bushman said.
With a faster life strategy and an orientation toward the present, people
have to practice less self-control, he said. That can lead people to react
more quickly with aggression and sometimes violence.
The theory is not deterministic and isn't meant to suggest that people in
hotter, consistent climates can't help themselves when it comes to violence
"How people approach life is a part of culture and culture is strongly
affected by climate," Van Lange said. "Climate doesn't make a person, but it
is one part of what influences each of us. We believe it shapes the culture
in important ways," he said.
Since CLASH is a new theory, studies have to be done to prove it is correct.
But Bushman said a lot of evidence already suggests that the theory may be
on to something.
"We believe CLASH can help account for differences in aggression and
violence both within and between countries around the world," he said. "We
think it provides a strong framework for understanding the violence
differences we see around the world."
The above post is reprinted from materials provided by Ohio State
University. The original item was written by Jeff Grabmeier.
Paul A. M. Van Lange, Maria I. Rinderu, and Brad J. Bushman. Aggression and
Violence Around the World: A Model of CLimate, Aggression, and Self-control
in Humans (CLASH). Behavioral and Brain Sciences, June 2016.