An integrated assessment of vascular plants species of the Americas

Tropical forest.

Missouri Botanical Garden researcher Dr. Carmen Ulloa is the lead author of "An Integrated Assessment of Vascular Plant Species of the Americas," published today in Science. Ulloa along with 23 co-authors compiled a comprehensive, searchable checklist of 124,993 species, 6,227 genera and 355 families of vascular plants of the Americas. This represents one third of all known vascular plants worldwide.

Establishing a checklist like this one has long been a goal of the Garden. In 2015, Ulloa started to research what already existed among existing Garden projects and other botanical institutions across the Americas. She then contacted the editors of the 12 major projects in the last 25 years that served as the basis for this larger checklist including the checklists of Bolivia, Brazil, Colombia, Ecuador, the Guianas, Mexico, Peru, the Southern Cone (Argentina, Chile, Paraguay, Uruguay), Venezuela, and the West Indies. Two partially published datasets of the Flora of North America North of Mexico and the Flora Mesoamericana were also used.

The Garden's plant database, Tropicos® was used as the projects data repository for the project. In the process, more than 25,000 names were added to Tropicos before a final list was compiled.

"This is the first time we have a complete overview of the plants of the Americas," said Ulloa. "It represents not only hundreds of years of plant collecting, and botanical research, but 6,164 botanists who described species that appear on this list. It is vital we have this information so that we know what each species is for conservation purposes."

Co-author Dr. Robert Magill first developed Tropicos in the early 1980s on tiny Osborne 01 microcomputer. Today, it is the world's largest botanical database. It is accessed more 70 million times each year by researchers around the world. It is a link to the past, a digital version of 4.4 million specimens in the Garden's expansive Herbarium. It is also a link to the future, the basis of a larger project, the World Flora Online. The Missouri Botanical Garden and more than 40 other institutions are working to develop the World Flora Online with the goal of documenting all known plant life by 2020.

A number of co-authors are current or former members of the Missouri Botanical Garden research staff including Dr. Gerrit Davidse, Heather Stimmel, Dr. James Zarucchi, Dr. Peter Jørgensen, Magill and Garden President Emeritus Dr. Peter Raven. In addition to this, Dr. Tom Croat and Dr. Charlotte Taylor are both acknowledged in the study's supplemental material for having more than 400 described plant species on the Americas list.

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How odors are turned into long-term memories

Neuroscientists from Bochum have investigated why the brain stores some odours in a special way.

The neuroscientists Dr Christina Strauch and Prof Dr Denise Manahan-Vaughan from the Ruhr-Universität Bochum have investigated which brain area is responsible for storing odours as long-term memories. Some odours can trigger memories of experiences from years back. The current study shows that the piriform cortex, a part of the olfactory brain, is involved in the process of saving those memories; the mechanism, however, only works in interaction with other brain areas. The findings have been published in the journal Cerebral Cortex.

"It is known that the piriform cortex is able to temporarily store olfactory memories. We wanted to know, if that applies to long-term memories as well," says Christina Strauch.

Artificial sensation through stimulation

Synaptic plasticity is responsible for the storing of memories in the memory structures of the brain: During that process the communication between neurons is altered by means of a process called synaptic plasticity, so that a memory is created. Strauch and Manahan-Vaughan examined if the piriform cortex of rats is capable of expressing synaptic plasticity and if this change lasts for more than four hours; indicating that long-term memory may have been established.

The scientists used electrical impulses in the brain to emulate processes that trigger the encoding of an olfactory sensation as a memory. They used different stimulation protocols which varied in the frequency and intensity of the pulses. It is known that these protocols can induce long-term effects in another brain area that is responsible for long term memories: the hippocampus. Strikingly, the same protocols did not induce long-term information storage in the form of synaptic plasticity in the piriform cortex.

Signal from a higher brain area needed

The scientists wondered whether the piriform cortex needs to be instructed to create a long-term memory. They then stimulated a higher brain area called the orbitofrontal cortex, which is responsible for the discrimination of sensory experiences. This time the stimulation of the brain area generated the desired change in the piriform cortex. "Our study shows that the piriform cortex is indeed able to serve as an archive for long-term memories. But it needs instruction from the orbitofrontal cortex -- a higher brain area -- indicating that an event is to be stored as a long-term memory," says Strauch.

From Science Daily

Plants reveal decision-making abilities under competition

The plant Potentilla reptans growing under simulated sparse vegetation.

Biologists from the University of Tübingen have demonstrated that plants can choose between alternative competitive responses according to the stature and densities of their opponents. A new study by researchers from the Institute of Evolution and Ecology reveals that plants can evaluate the competitive ability of their neighbors and optimally match their responses to them. The results were published in Nature Communications.

Animals facing competition have been shown to optimally choose between different behaviors, including confrontation, avoidance and tolerance, depending on the competitive ability of their opponents relative to their own. For example, if their competitors are bigger or stronger, animals are expected to "give up the fight" and choose avoidance or tolerance over confrontation.

Plants can detect the presence of other competing plants through various cues, such as the reduction in light quantity or in the ratio of red to far-red wavelengths (R:FR), which occurs when light is filtered through leaves. Such competition cues are known to induce two types of responses: confrontational vertical elongation, by which plants try to outgrow and shade their neighbors, and shade tolerance, which promotes performance under limited light conditions. Some plants, such as clonal plants, can exhibit avoidance behavior as a third response type: they grow away from their neighbors. "These three alternative responses of plants to light competition have been well-documented in the literature," says Michal Gruntman, lead author of the paper. "In our study we wanted to learn, if plants can choose between these responses and match them to the relative size and density of their opponents."

To answer this question, the researchers used the clonal plant Potentilla reptans in an experimental setup that simulated different light-competition settings. They used vertical stripes of transparent green filters that reduce both light quantity and R:FR and could therefore provide a realistic simulation of light competition. By changing both the height and density of this simulated vegetation, the researchers could present different light-competition scenarios to the plants.

The results demonstrated that Potentilla reptans can indeed choose its response to competition in an optimal way. When the plants were under treatments simulating short-dense neighbors, which presented competitors that where too dense to avoid laterally but could be outgrown vertically, Potentilla reptans showed the highest confrontational vertical growth. However, under simulated tall-dense neighbors, which could not be outgrown either vertically or laterally, plants displayed the highest shade tolerance behavior. Lastly, under tall-sparse neighbors, which could only be avoided laterally, plants exhibited the highest lateral-avoidance behaviors.

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A 508-million-year-old sea predator with a 'jackknife' head

Fossil specimen of Habelia optata from the Royal Ontario Museum. This specimen spectacularly shows some of the very large jaws under the head shield. Note also the long dorsal spines on the thorax.

Paleontologists at the University of Toronto (U of T) and the Royal Ontario Museum (ROM) in Toronto have entirely revisited a tiny yet exceptionally fierce ancient sea creature called Habelia optata that has confounded scientists since it was first discovered more than a century ago.

The research by lead author Cédric Aria, recent graduate of the PhD program in the department of ecology & evolutionary biology in the Faculty of Arts & Science at U of T, and co-author Jean-Bernard Caron, senior curator of invertebrate palaeontology at the ROM and an associate professor in the departments of ecology & evolutionary biology and Earth sciences at U of T, is published today in BMC Evolutionary Biology.

Approximately 2 cm in length with a tail as long as the rest of its body, the long-extinct Habelia optata belongs to the group of invertebrate animals called arthropods, which also includes such familiar creatures as spiders, insects, lobsters and crabs. It lived during the middle Cambrian period approximately 508 million years ago and comes from the renowned Burgess Shale fossil deposit in British Columbia. Habelia optata was part of the "Cambrian explosion," a period of rapid evolutionary change when most major animal groups first emerged in the fossil record.

Like all arthropods, Habelia optata features a segmented body with external skeleton and jointed limbs. What remained unclear for decades, however, was the main sub-group of arthropods to which Habelia belonged. Early studies had mentioned mandibulates -- a hyperdiverse lineage whose members possess antennae and a pair of specialized appendages known as mandibles, usually used to grasp, squeeze and crush their food. But Habelia was later left as one of the typically unresolved arthropods of the Burgess Shale.

The new analysis by the U of T-ROM researchers suggests that Habelia optata was instead a close relative of the ancestor of all chelicerates, the other sub-group of arthropods living today, named for the presence of appendages called chelicerae in front of the mouth and used to cut food. This is mostly due to the overall anatomy of the head in Habelia, and the presence of two small chelicerae-like appendages revealed in these fossils.

"Habelia now shows in great detail the body architecture from which chelicerates emerged, which allows us to solve some long-standing questions," said Aria, who is now a post-doctoral researcher at the Nanjing Institute of Geology and Palaeontology, in China. "We can now explain why, for instance, horseshoe crabs have a reduced pair of limbs -- the chilaria -- at the back of their heads. Those are relics of fully-formed appendages, as chelicerates seem to originally have had heads with no less than seven pairs of limbs."

Aria and Caron analyzed 41 specimens in total, the majority of which are new specimens acquired by ROM-led fieldwork parties to the Burgess Shale.

The research illustrates that the well-armoured body of Habelia optata, covered in a multitude of different spines, was divided into head, thorax and post-thorax, all bearing different types of appendages. The thorax displays five pairs of walking legs, while the post-thorax houses rounded appendages likely used in respiration.

"Scorpions and the now-extinct sea scorpions are also chelicerates with bodies divided into three distinct regions," Aria explained. "We think that these regions broadly correspond to those of Habelia. But a major difference is that scorpions and sea scorpions, like all chelicerates, literally 'walk on their heads,' while Habelia still had walking appendages in its thorax."

The researchers argue that this difference in anatomy allowed Habelia to evolve an especially complex head that makes this fossil species even more peculiar compared to known chelicerates. The head of Habelia contained a series of five appendages made of a large plate with teeth for mastication, a leg-like branch with stiff bristle-like spines for grasping, and an elongate, slender branch modified as a sensory or tactile appendage.

"This complex apparatus of appendages and jaws made Habelia an exceptionally fierce predator for its size," said Aria. "It was likely both very mobile and efficient in tearing apart its preys."

The surprising outcome of this study, despite the evolutionary relationship of Habelia with chelicerates, is that these unusual characteristics led instead the researchers to compare the head of Habelia with that of mandibulates from a functional perspective. Thus, the peculiar sensory branches may have been used in a similar fashion as mandibulates use antennae. Also, the overlapping plate-like appendages in the middle series of five are shown to open and close parallel to the underside of the head -- much as they do in mandibulates, especially those that feed on animals with hardened carapaces.

Lastly, a seventh pair of appendages at the back of the head seems to have fulfilled a function similar to that of "maxillipeds" -- appendages in mandibulates that assist with the other head limbs in the processing of food. This broad correspondence in function rather than in evolutionary origin is called "convergence."

"From an evolutionary point of view, Habelia is close to the point of divergence between chelicerates and mandibulates," Aria said. "But its similarities with mandibulates are secondary modifications of features that were in part already chelicerate in nature. This suggests that chelicerates originated from species with a high structural variability."

The researchers conclude from the outstanding head structure, as well as from well-developed walking legs, that Habelia optata and its relatives were active predators of the Cambrian sea floors, hunting for small shelly sea creatures, such as small trilobites -- arthropods with hard, mineralized exoskeletons that were already very diverse and abundant during Cambrian times.

"This builds onto the importance of carapaces and shells for evolutionary change during the Cambrian explosion, and expands our understanding of ecosystems at this time, showing another level of predator-prey relationship and its determining impact on the rise of arthropods as we know them today," said Caron, who was Aria's PhD supervisor when the bulk of this research was completed.

Read more at Science Daily

Star in the constellation Pisces is 'eating' planets

This illustration shows a "disrupted planet" slowly broken up into a cloud of gas and dust as it orbits the star RZ Piscium about 550 light years from Earth.

Like the ancient Greek god Cronus who devoured his children, a star 550 light years from Earth has been discovered to be slowly consuming its "offspring" -- crushing one or more planets in its orbit into vast clouds of gas and dust.

The discovery that RZ Piscium -- located in the constellation Pisces -- is an insatiable "eater of worlds" was reported today in The Astronomical Journal. Indiana University astronomer Catherine Pilachowski is co-author on the study, titled "Is the Young Star RZ Piscium Consuming Its Own (Planetary) Offspring?"

The discovery may shed light on a brief but volatile period in the history of many solar systems, including our own.

"We know it's not uncommon for planets to migrate inward in young solar systems since we've found so many solar systems with 'hot Jupiters' -- gaseous planets similar in size to Jupiter but orbiting very close to their stars," said Pilachowski, who is the Daniel Kirkwood Chair in the IU Bloomington College of Arts and Sciences' Department of Astronomy. "This is a very interesting phase in the evolution of planetary systems, and we're lucky to catch a solar system in the middle of the process since it happens so quickly compared to the lifetimes of stars."

Doomed worlds that fly too close to their sun -- only to be ripped apart by its tidal forces -- are officially known as "disrupted planets." In the case of RZ Piscium, the material near the sun-like star is being slowly pulled apart to create a small circle of debris about the same distance from the star as the planet Mercury's orbit is from our sun.

"Based on our observations, it seems either that we're seeing a fairly massive, gaseous planet being pulled apart by the star, or perhaps two gas-rich planets that have collided and been torn apart," Pilachowski said of RZ Piscium.

Even solar systems whose planets are not lost to their sun are unstable in their early history, since newly born planets interact strongly with one another -- as well as their sun -- through gravity, she added. In our solar system, for example, some astronomers speculate that Uranus and Neptune swapped orbits about 4 billion years ago. But erratic orbits tend to stabilize over time, falling into regular patterns.

An expert on the analysis of light spectrum from distant stars to determine their temperature, gravity and elemental composition, Pilachowski was responsible in the new study for determining the gravitational strength near RZ Piscium's surface. The observation helped shed light on the star's radius and brightness, both of which suggest a young star in the midst of a freewheeling solar system with unstable planets.

This is significant because RZ Piscium's age was uncertain. The debris field around a star can result from either the erratic orbits in young solar systems or the destruction of planets that occurs as an old star grows before collapsing and dying.

Pilachowski's analysis of the star's light also helped determine the amount of lithium in the star, marking the star as a relatively young 30 million to 50 million years. Astronomers can use lithium levels to estimate a star's age because the element declines over time.

The study's authors also found the star's temperature to be about 9,600 degrees Fahrenheit (5,330 degrees Celsius) -- only slightly cooler than our sun's. Another sign of the star's relative youth: It produces X-rays at a rate roughly 1,000 times greater than our sun.

Read more at Science Daily

The origin of water's unusual properties found

Illustration showing fluctuations between regions of two different local structures (high density as red and low density liquid as blue) of water that depend on the temperature. Maxima in the thermodynamic response and correlation functions are observed as a function of temperature, when the numbers of molecules in the two structures become equal, resulting in strong enhancement in the anomalous properties of water in the deeply supercooled regime.

Using x-ray lasers, researchers at Stockholm University have been able to map out how water fluctuates between two different states when it is cooled. At -44°C these fluctuations reach a maximum pointing to the fact that water can exist as two different distinct liquids. The findings will be published in the journal Science.

Water, both common and necessary for life on earth, behaves very strangely in comparison with other substances. How water's density, specific heat, viscosity and compressibility respond to changes in pressure and temperature is completely opposite to other liquids that we know.

We all are aware that all matter shrinks when it is cooled resulting in an increase in the density. We would therefore expect that water would have high density at the freezing point. However, if we look at a glass of ice water, everything is upside down, since we expect that water at 0°C being surrounded by ice should be at the bottom of the glass, but of course as we know ice cubes float. Strangely enough for the liquid state, water is the densest at 4 degrees C, and therefore it stays on the bottom whether it's in a glass or in an ocean.

If you chill water below 4 degrees, it starts to expand again. If you continue to cool pure water (where the rate of crystallization is low) to below 0, it continues to expand -- the expansion even speeds up when it gets colder. Many more properties such as compressibility and heat capacity become increasingly strange as water is cooled. Now researchers at Stockholm University, with the help of ultra-short x-ray pulses at x-ray lasers in Japan and South Korea, have succeeded in determining that water reaches the peak of its strange behaviour at -44°C.

Water is unique, as it can exist in two liquid states that have different ways of bonding the water molecules together. The water fluctuates between these states as if it can't make up its mind and these fluctuations reach a maximum at -44°C. It is this ability to shift from one liquid state into another that gives water its unusual properties and since the fluctuations increase upon cooling also the strangeness increases.

"What was special was that we were able to X-ray unimaginably fast before the ice froze and could observe how it fluctuated between the two states," says Anders Nilsson, Professor of Chemical Physics at Stockholm University. "For decades there has been speculations and different theories to explain these remarkable properties and why they got stronger when water becomes colder. Now we have found such a maximum, which means that there should also be a critical point at higher pressures."

Another remarkable finding of the study is that the unusual properties are different between normal and heavy water and more enhanced for the lighter one. "The differences between the two isotopes, H2O and D2O, given here shows the importance of nuclear quantum effects," says Kyung Hwan Kim, postdoc in Chemical Physics at Stockholm University. "The possibility to make new discoveries in a much studied topic such as water is totally fascinating and a great inspiration for my further studies," says Alexander Späh, PhD student in Chemical Physics at Stockholm University.

"It was a dream come true to be able to measure water under such low temperature condition without freezing" says Harshad Pathak, postdoc in Chemical Physics at Stockholm University. "Many attempts over the world have been made to look for this maximum."

Read more at Science Daily

An Opioid Vaccine Developed by the US Military Could Combat Addiction

A heroin user prepares to shoot up on the street in a South Bronx neighborhood which has the highest rate of heroin-involved overdose deaths in the city on October 7, 2017 in New York City.

For the first time in a half a century, life expectancy in the United States declined for the second year in a row — and America’s opioid epidemic is to blame. A child born in 2016 is expected to live 78.6 years, down from 78.7 years in 2015 and 78.9 in 2014, according to statistics released by the US Centers for Disease Control and Prevention.

"Two years in a row is quite shocking," Robert Anderson, chief of the mortality statistics branch at the National Center for Health Statistics, told AFP. "The key factor in all this is the increase in drug overdose deaths."

Yet amid the overdose epidemic, another opioid vaccine has shown promising — albeit early — results in the laboratory.

Scientists at the US Military HIV Research Program at the Walter Reed Army Institute of Research (WRAIR) recently developed a vaccine that blocks the opioids in heroin from reaching the brain in mice and rats, offering a potential breakthrough in treating opioid addiction.

When injected, the heroine vaccine releases antibodies into the blood that prohibit the drug from breaking through the blood-brain barrier. This means that even if a heroin addict shoots up, they won’t experience a high. The vaccine includes a potent adjuvant, a substance that boosts the body’s immune response to a toxin, called the Army Liposome Formulation, also developed by researchers at WRAIR.

“All vaccines to substances of abuse function through causing the body to make antibodies that bind the drug of interest and prevent it from entering the brain,” Dr. Gary Matyas, chief of adjuvants and formulations for the US Military Research Program and one of the study authors, told Seeker.

While Matyas and his team have not directly tested their vaccine against vaccines from other research facilities, they have tested it against an older vaccine developed by WRAIR and found that the new one is more effective and very stable. “[Its stability] should increase its shelf-life and keep it from degrading during vaccine manufacturing and storage,” Matyas said.

Their study, published in the Journal of Medicinal Chemistry, found that this new vaccine was not only effective in preventing heroin from reaching the brain but worked with other commonly abused opioids as well, including hydrocodone, oxycodone, hydromorphone, oxymorphone, and codeine. It also lowered the toxic effect of very high doses of heroin, which could be key in preventing overdoses.

The antibodies in the vaccine did not bind to several other opioids like methadone, tramadol, sufentanil, nalbuphine, buprenorphine, and fentanyl. Fentanyl is one of the most widely abused synthetic forms of heroin and 100 times more powerful, which makes it extremely deadly. Due to the high risk of overdose, some researchers have prioritized the development of a treatment method specifically for fentanyl abuse. Along with their heroin vaccine, the Scripps Institute tested a fentanyl vaccine in mice and found it to be similarly effective, but clinical trials are still needed.

The discovery that the WRAIR vaccine does not interfere with opioids like methadone and buprenorphine turned out to be a positive development, as these drugs are often used in current treatment methods for opioid addiction. Because the vaccine’s antibodies do not bind with methadone, buprenorphine, or naltrexone, it can potentially be used in combination with these therapies.

Most importantly, the vaccine did not react with naloxone, which is used in emergency overdose rescue treatments to reverse respiratory complications. And it did not react to non-opioid pain relievers like ibuprofen or aspirin.

While this research is an important advancement in treating opioid addiction, it could be several years before the vaccine is commercially available. “Vaccines typically take many years to develop, test, and manufacture, and we are still in the early stages,” Matyas said. “We are currently pursuing funding for a clinical trial [and] we have licensed the product to Opiant Pharmaceuticals to continue development and manufacture at the appropriate point.”

Administering methadone or buprenorphine is the most common treatment option for heroin addicts, but these methods are often expensive and require inconvenient daily trips to a clinic. What’s more, the chance of relapse afterwards is very high. 91 people die every day from an opioid overdose in the US, according to the CDC. By addressing the issue of relapse due to intense cravings, this new vaccine offers one additional solution for treatment.

The US military’s vaccine, funded by the National Institute of Health, the Henry M. Jackson Foundation for the Advancement of Military Medicine, and the US Army, is not the only one in development. In June, the Scripps Research Institute published their work on a similar vaccine that was found to be effective in mice, as well as rhesus monkeys, and other opioid vaccines are also being developed and tested in order to address the growing epidemic.

Read more at Seeker

Beauty is in the eye of the beer holder

Men under the influence of alcohol are more likely to see women as sexual objects. This is according to a study which moves beyond the mere anecdotal to investigate some of the circumstances and factors that influence why men objectify women. The research is published in Springer's journal Sex Roles and is led by Abigail Riemer of the University of Nebraska-Lincoln in the US.

The study involved 49 men in their twenties and was conducted in the safe space of a college laboratory. Of the 49 subjects, 29 received two alcoholic drinks to mildly intoxicate them, and the rest received placebo drinks. All were shown photographs of 80 undergraduate women dressed to go out, and were asked to rate the women's appearances and personality. The women's photos were previously rated by an independent panel on how much warmth, good-naturedness, friendliness, competence, intelligence, confidence, and attractiveness they exuded. Eye-tracking technology noted which part of the women's bodies men were looking at when they were shown the images.

When the men assessed a photographed woman based on her appearance, the instruction most often triggered objectifying gazes from them. They spent less time looking at faces and focused far longer on chests and waists. This was particularly true when viewing women who had been rated high in attractiveness. It happened to a lesser degree when viewing women who exuded warmth and competence, especially when men were slightly drunk. The findings suggest that whether a man will sexually objectify a woman depends on the alcohol intoxication of the man, as well as how attractive, warm and competent a woman is perceived to be.

"The sum of these results supports the notion that being perceived as high in humanizing attributes, such as warmth and competence, or being average in attractiveness provides a buffer that protects women from sexual objectification," says Riemer.

"Environments in which alcohol is present are ripe with opportunities for objectifying gazes," adds Riemer, who says that the only other study previously done on the link between alcohol and objectification by men relied on self-reports from women. "Adopting objectifying gazes toward women leads perceivers to dehumanize women, potentially laying the foundation for many negative consequences such as sexual violence and workplace gender discrimination."

She hopes findings from the study will help to challenge specific maladaptive beliefs held by some men that it is OK and acceptable to direct objectifying gazes toward women, especially those who are not typically considered to be attractive or who are not perceived as being competent or to have a warm personality.

Read more at Science Daily

North Atlantic Oscillation synchronizes tree reproduction across Europe

Research by the University of Liverpool has found a strong correlation between the North Atlantic Oscillation and synchronised tree reproduction across Europe, supporting the idea that this phenomenon plays a greater role in large scale masting, the process whereby forest trees produce large numbers of seeds in the same year.

The North Atlantic Oscillation (NAO) refers to the large scale changes in pressure that occur naturally in the North Atlantic region. It has been shown to have a strong effect on atmospheric circulation and European climate.

It is known that tree reproduction tends to be strongly synchronised within local populations, so that if one tree is producing a very heavy seed or fruit crop, it is very likely that a neighbouring tree will also be heavily fruiting.

However, in a study, published in Nature Communications researchers analysed tree masting observational data taken over a 190-year period for two key tree species in Europe, European beech and Norway spruce, and compared this to data on the Northern Atlantic Oscillation.

They found that in 1976, 1995 and 2011, both of these species across all of Europe simultaneously produced heavy seed crops.

The researchers found that for the last sixty years continent-wide masting in beech and spruce coincided with high-frequency summer- and spring-NAO and low-frequency winter-NAO. It also reveals a weaker relationship between NAO and masting for the first part of the twentieth century.

Dr Andrew Hacket-Pain, Lecturer in Biogeography and Ecology at the University's Department of Geography and Planning, said: "Our work shows that the remarkable synchronisation of behaviour across such vast distances is linked to the North Atlantic Oscillation.

"We think this is because a strong NAO synchronises climate across large parts of Europe, especially during key phases of the tree reproduction cycle. This helps to synchronise seed crops across such large areas, but future work will be required to firmly establish this mechanism.

"The synchronisation of seed production is important, as it has knock-on effects on forest ecosystems. For example, heavy seed crops increase food availability for woodland-based birds and small animals, and consequently tend to increase the size of such animal populations in the short-term. Additionally, it has implications for human health, as the increase in animal hosts has a positive effect on tick numbers."

Read more at Science Daily

How plants form their seeds

Pollen tubes with internalized, fluorescence-labelled signal substances (RALF peptides).

Around 80 to 85 percent of our calorie needs is covered through seeds, either directly as food or indirectly through use as feed. Seeds are the result of plant reproduction. During the flowering period, the male and female tissues interact with each other in a number of ways. When pollen lands on the flower's stigma, it germinates and forms a pollen tube, which then quickly grows towards the plant's ovary. Once it finds an ovule, the pollen tube bursts to release sperm cells, which fertilize the ovule and initiate seed formation.

Pollen tube interacts with female plant tissue

Led by Ueli Grossniklaus, professor at the Department of Plant and Microbial Biology at the University of Zurich, an international research team has now demonstrated how the pollen tube interacts with, and responds to, female plant tissue. The pollen tube does so by secreting extracellular signals (RALF peptides) which it uses to explore its cellular environment and regulate its growth. Two receptors on the cell's surface enable it to perceive the secreted signals and transmit them to the inside of the cell.

Intracellular signals regulate growth

Working together with the teams of Christoph Ringli from UZH and Jorge Muschietti from the University of Buenos Aires, the team around Grossniklaus was able to determine that further proteins had to be active for the pollen tube to recognize the signals -- LRX proteins. These proteins were identified at UZH 15 years ago by Beat Keller and his research group, but their function had previously not been clear. LRX proteins are localized in the cell wall surrounding plant cells, where the signals can dock. "We suspect that the pollen tube explores changes in the cell wall by sending out signals and responding accordingly, for example by realigning its growth," says Ueli Grossniklaus. It is rare for plants to produce and perceive signals with the same cells. The researchers suspect that this allows the pollen tube, which grows extremely quickly, to faster respond to changes in its environment rather than being dependent on signals from other neighboring cells.

Molecular insights open up wide range of potential applications

The signaling pathways described by the researchers are involved in many other basic processes, and knowledge of how they work opens up numerous possible applications for plant breeding. "By better understanding how these proteins work, we can not only influence pollination and seed formation, but also the development and growth of plants or their defense against pests," concludes Ueli Grossniklaus.

From Science Daily