Signing

The speed at which sign language users understand what others are ‘saying’ to them depends on whether the conversation partners are left- or right-handed, a new study has found.

Researchers at the University of Birmingham worked with British Sign Language (BSL) signers to see how differences in sign production affect sign comprehension. In BSL a signer’s dominant hand produces all one-handed signs and ‘leads’ when producing two-handed signs.

They discovered that in general right- and left-handed signers respond faster when they were watching a right-handed signer.

However, left-handed signers responded more quickly to complex two-handed signs made by signers who ‘led’ with their left hand. Similarly, right-handed signers reacted more swiftly to two-handed signs from fellow right-handers.

PhD student Freya Watkins and Dr. Robin Thompson published their research in the journal Cognition.

Dr Robin Thompson commented: “Had all signers performed better to right-handed input, it would suggest that how signers produce their own signs is not important for understanding. This is because right-handed signers are most common and signers are most used to seeing right-handed signs.

“However, as left-handed signers are better at understanding fellow left-handers for two-handed signs, the findings suggest that how people produce their own signs plays a part in how quickly they can understand others’ signing.”

Forty-three Deaf fluent BSL signers took part in the experiment, which had both right and left-handed participants make judgements about signs produced by left or right-handed sign models.

Participants were shown a picture followed by the sign for common words such as ‘chocolate’, ‘guitar’ and ‘desk’, and then were asked to decide if the picture and sign matched. The question was whether or not handedness during sign production would influence sign comprehension.

The results are in line with a weak version of the motor theory of speech perception, that people perceive spoken words in part by checking in with their own production system, but only when comprehension becomes difficult, for example in a noisy environment.

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Nature’s Plough

The digging, stirring and overturning of soil by conventional ploughing in tillage farming is severely damaging earthworm populations around the world, say scientists.

The findings published in the scientific journal Global Change Biology show a systematic decline in earthworm populations in soils that are ploughed every year. The deeper the soil is disturbed the more harmful it is for the earthworms.

The scientists from the University of Vigo, Spain and University College Dublin, Ireland, analysed 215 field studies from across 40 countries dating back as far as 1950. Each of the studies investigated earthworm populations under conventional tillage and other forms of reduced tillage.

“What we see is a systematic decline in the earthworm population in the soil after continued ploughing and a significant increase in the abundance of earthworms in less disturbed soil, although some soils would need more than 10 years to show good signs of recovery” says Associate Professor Olaf Schmidt, from the UCD School of Agriculture and Food Science, University College Dublin.

According to the findings, the earthworm populations most vulnerable to tillage are larger earthworms that move between layers of soil and create permanent burrows between them (anecic earthworms). Small earthworms that live in the top layers of soil and convert debris to topsoil (epigeic earthworms) were also found to be highly susceptible.

Farming practices that involve no-tillage, Conservation Agriculture and shallow non-inversion tillage were shown to significantly increase earthworm populations. The scientists note that these reduced tillage practices are increasingly being adopted world-wide due to their environmental benefits in terms of erosion control and soil protection.

“Our study also identifies the conditions under which earthworms respond most to a reduction in tillage intensity. These findings can be translated into advice for farmers in different parts of the world,” explains Professor Maria Briones from the University of Vigo.

“For example, strong results are achieved in soils with higher clay contents (>35%) and low pH (<5.5), and retaining organic harvest residues amplifies the effects. The controversial herbicide glyphosate did not significantly affect earthworm population responses to reduced tillage.”

Earthworms are critical to the maintenance of soil functions and the ecosystem services we expect from them. The great evolutionary biologist, Charles Darwin called earthworms “nature’s plough” because they continually consume and defecate soil enhancing its fertility in the process.

In his experiments in England in the late 1800s, Darwin found about 54,000 earthworms inhabited each acre of land and that each of these populations turn over tens of tons of topsoil every year.

Recognizing the critical ecological value of earthworms, Darwin wrote: “It may be doubted whether there are any other animals which have played so important a part in the history of the world as have these lowly, organized creatures.”

Professor Maria Briones concludes “Switching to reduced tillage practices is a win-win situation for farmers because they save costs and in return larger earthworm populations help in soil structure maintenance and nutrient cycling.”

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Glucose Monitors

After a meal, beta cells in the pancreas sense rising blood glucose and release the hormone insulin, which helps the sugar enter cells, where it can be used by the body for energy.

Now researchers at the University of Michigan Life Sciences Institute have uncovered an unexpected mechanism of glucose sensing in skeletal muscles that contributes to the body’s overall regulation of blood sugar levels.

“We found that skeletal muscle cells have machinery to directly sense glucose;  in a certain sense it’s like the muscles can taste sugar too,” said senior study author Jiandie Lin, a faculty member at the LSI, where his lab is located.

This ability of muscles to sense blood glucose is a separate and parallel process that augments the insulin-driven response. Together they work as a rheostat to maintain steady glucose levels in the body, particularly after a meal, according to findings published in Molecular Cell.

Continuing to develop this in-depth understanding of how the body self-regulates blood sugar at the molecular level could shed new light on obesity and diabetes, as well as point toward new therapeutic targets, said Zhuoxian Meng, the study’s lead author and a research investigator in Lin’s lab.

The researchers were able to examine the contributions of the glucose-sensing pathway in skeletal muscle by silencing a key gene, BAF60C  in cell cultures and in laboratory mice.

“When we did that, the mice lacking BAF60C looked absolutely normal, but after we gave them a high-fat diet to induce obesity, they developed trouble disposing of the additional glucose after a meal,” Lin said. “The well-known insulin mechanism was not sufficient to process the glucose on its own.”

Elevated blood sugar following a meal is a key symptom of Type 2 diabetes. And chronic high blood sugar, also known hyperglycemia, can lead to serious health issues.

“We found that the molecular pathway that’s engaged by glucose in muscle cells, at least the initial steps, is very similar to what happens in the beta cells in the pancreas,” said Lin, who is also a professor of cell and developmental biology at the U-M Medical School. “This is very interesting because there’s a very important class of diabetes drugs known as sulfonylureas that act by closing a potassium channel and causing the beta cells to secrete more insulin.

“Our research shows that this glucose-sensing pathway in muscle cells likely also plays a role in the drugs’ overall glucose-lowering action. The extent of the pathway’s contribution will need to be studied further.”

Additionally, Lin said, there are two steps within the glucose-sensing pathway that could serve as potential targets for modulation with therapeutic compounds.

“It’s amazing how subtle changes in glucose can be detected throughout the body,” Lin said. “Beta cells respond, nerve cells respond, and now we know that muscle cells respond directly, too.”

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Rice Risks

In January 2016, the EU imposed a maximum limit of inorganic arsenic on manufacturers in a bid to mitigate associated health risks. Researchers at the Institute for Global Food Security at Queen’s have found that little has changed since this law was passed and that 50 per cent of baby rice food products still contain an illegal level of inorganic arsenic.

Professor Meharg, lead author of the study and Professor of Plant and Soil Sciences at Queen’s, said: “This research has shown direct evidence that babies are exposed to illegal levels of arsenic despite the EU regulation to specifically address this health challenge. Babies are particularly vulnerable to the damaging effects of arsenic that can prevent the healthy development of a baby’s growth, IQ and immune system to name but a few.”

Rice has typically, ten times more inorganic arsenic than other foods and chronic exposure can cause a range of health problems including developmental problems, heart disease, diabetes and nervous system damage.

As babies are rapidly growing they are at a sensitive stage of development and are known to be more susceptible to the damaging effects of arsenic, which can inhibit their development and cause long-term health problems. Babies and young children under the age of five also eat around three times more food on a body weight basis than adults, which means that relatively, they have three times greater exposures to inorganic arsenic from the same food item.

The research findings, published in the PLOS ONE journal today, compared the level of arsenic in urine samples among infants who were breast-fed or formula-fed before and after weaning. A higher concentration of arsenic was found in formula-fed infants, particularly among those who were fed non-dairy formulas which includes rice-fortified formulas favoured for infants with dietary requirements such as wheat or dairy intolerance. The weaning process further increased infants’ exposure to arsenic, with babies five times more exposed to arsenic after the weaning process, highlighting the clear link between rice-based baby products and exposure to arsenic.

In this new study, researchers at Queen’s also compared baby food products containing rice before and after the law was passed and discovered that higher levels of arsenic were in fact found in the products since the new regulations were implemented. Nearly 75 per cent of the rice-based products specifically marketed for infants and young children contained more than the standard level of arsenic stipulated by the EU law.

Rice and rice-based products are a popular choice for parents, widely used during weaning and to feed young children, due to its availability, nutritional value and relatively low allergic potential.

Professor Meharg explained: “Products such as rice-cakes and rice cereals are common in babies’ diets. This study found that almost three-quarters of baby crackers, specifically marketed for children exceeded the maximum amount of arsenic.”

Previous research led by Professor Meharg highlighted how a simple process of percolating rice could remove up to 85 per cent of arsenic. Professor Meharg adds: “Simple measures can be taken to dramatically reduce the arsenic in these products so there is no excuse for manufacturers to be selling baby food products with such harmful levels of this carcinogenic substance.

“Manufacturers should be held accountable for selling products that are not meeting the required EU standard. Companies should publish the levels of arsenic in their products to prevent those with illegal amounts from being sold. This will enable consumers to make an informed decision, aware of any risks associated before consuming products containing arsenic.”

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New Monitor Monicker

Scientists have recently found and re-described a monitor lizard species from the island of New Ireland in northern Papua New Guinea. It is the only large-growing animal endemic to the island that has survived until modern times. The lizard, Varanus douarrha, was already discovered in the early 19th century, but the type specimen never reached the museum where it was destined as it appears to have been lost in a shipwreck.

The discovery is particularly interesting as most of the endemic species to New Ireland disappeared thousands of years ago as humans colonised the island.

The monitor was discovered during fieldwork by Valter Weijola from the Biodiversity Unit of the University of Turku, Finland, who spent several months surveying the monitor lizards of the Bismarck Islands. It can grow to over 1.3 metres in length and according to current information, it is the only surviving large species endemic to the island. Based on bone discoveries, scientists now know that at least a large rat species and several flightless birds have lived in the area.

“In that way it can be considered a relic of the historically richer fauna that inhabited the Pacific islands. These medium-sized Pacific monitors are clearly much better at co-existing with humans than many of the birds and mammals have been,” says Weijola.

Scientists have known for a long time that there are monitor lizards on the island but it has been unclear which species they belong to. French naturalist René Lesson discovered the monitor lizard when visiting the island with the La Coquille exploration ship in 1823, and later named the species Varanus douarrha which, according to Lesson, means monitor lizard in the local Siar-Lak language.

However, it seems likely that Lesson’s specimen was destroyed on the way to France as the ship that was carrying it shipwrecked at the Cape of Good Hope in 1824. Therefore, biologists never had a chance to study the so called holotype or name-bearing specimen.

“Since then, it has been believed that the monitor lizards on New Ireland belong to the common mangrove monitor (Varanus indicus) that occurs widely in northern Australia, New Guinea and surrounding islands. However, new morphological and genetic studies confirmed that the monitor lizards of New Ireland have lived in isolation for a long time and developed into a separate species,” says Weijola.

The discovery was published in the Australian Journal of Zoology and where Varanus douarrha was re-described in detail, and given a new name bearing specimen.

Another monitor lizard, Varanus semotus, was described from Mussau Island last year by the same team of scientists.

“Together, these two species have doubled the number of monitor lizard species known to occur in the Bismarck Archipelago and proved that there are more endemic vertebrates on these islands than previously believed,” says Weijola.

Monitor lizards are important predators and altogether approximately 90 different species are known to live in Africa, Asia, Australia and the Pacific islands. Most monitor lizards occur in Australia and on the Pacific islands where there are few mammalian predators. Despite their large size, many of the species are poorly known and new ones are regularly discovered. Most of them stay out of sight and inhabit remote areas which are difficult to access.

Monitor Lizard