Author Archives: Bora Zivkovic

There are 12 new articles in PLoS ONE today. I guess picking all 12 would not really be ‘picking’? But all 12 are interesting to me! OK, here are six, and you go and look at the other six as well. As always, you should rate the articles, post notes and comments and send trackbacks when you blog about the papers.
Social Waves in Giant Honeybees Repel Hornets:

Giant honeybees (Apis dorsata) nest in the open and have evolved a plethora of defence behaviors. Against predatory wasps, including hornets, they display highly coordinated Mexican wave-like cascades termed ‘shimmering’. Shimmering starts at distinct spots on the nest surface and then spreads across the nest within a split second whereby hundreds of individual bees flip their abdomens upwards. However, so far it is not known whether prey and predator interact and if shimmering has anti-predatory significance. This article reports on the complex spatial and temporal patterns of interaction between Giant honeybee and hornet exemplified in 450 filmed episodes of two A. dorsata colonies and hornets (Vespa sp.). Detailed frame-by-frame analysis showed that shimmering elicits an avoidance response from the hornets showing a strong temporal correlation with the time course of shimmering. In turn, the strength and the rate of the bees’ shimmering are modulated by the hornets’ flight speed and proximity. The findings suggest that shimmering creates a ‘shelter zone’ of around 50 cm that prevents predatory wasps from foraging bees directly from the nest surface. Thus shimmering appears to be a key defence strategy that supports the Giant honeybees’ open-nesting life-style.

Functional MRI of Auditory Responses in the Zebra Finch Forebrain Reveals a Hierarchical Organisation Based on Signal Strength but Not Selectivity:

Male songbirds learn their songs from an adult tutor when they are young. A network of brain nuclei known as the ‘song system’ is the likely neural substrate for sensorimotor learning and production of song, but the neural networks involved in processing the auditory feedback signals necessary for song learning and maintenance remain unknown. Determining which regions show preferential responsiveness to the bird’s own song (BOS) is of great importance because neurons sensitive to self-generated vocalisations could mediate this auditory feedback process. Neurons in the song nuclei and in a secondary auditory area, the caudal medial mesopallium (CMM), show selective responses to the BOS. The aim of the present study is to investigate the emergence of BOS selectivity within the network of primary auditory sub-regions in the avian pallium. Using blood oxygen level-dependent (BOLD) fMRI, we investigated neural responsiveness to natural and manipulated self-generated vocalisations and compared the selectivity for BOS and conspecific song in different sub-regions of the thalamo-recipient area Field L. Zebra finch males were exposed to conspecific song, BOS and to synthetic variations on BOS that differed in spectro-temporal and/or modulation phase structure. We found significant differences in the strength of BOLD responses between regions L2a, L2b and CMM, but no inter-stimuli differences within regions. In particular, we have shown that the overall signal strength to song and synthetic variations thereof was different within two sub-regions of Field L2: zone L2a was significantly more activated compared to the adjacent sub-region L2b. Based on our results we suggest that unlike nuclei in the song system, sub-regions in the primary auditory pallium do not show selectivity for the BOS, but appear to show different levels of activity with exposure to any sound according to their place in the auditory processing stream.

Valuing Insect Pollination Services with Cost of Replacement:

Value estimates of ecosystem goods and services are useful to justify the allocation of resources towards conservation, but inconclusive estimates risk unsustainable resource allocations. Here we present replacement costs as a more accurate value estimate of insect pollination as an ecosystem service, although this method could also be applied to other services. The importance of insect pollination to agriculture is unequivocal. However, whether this service is largely provided by wild pollinators (genuine ecosystem service) or managed pollinators (commercial service), and which of these requires immediate action amidst reports of pollinator decline, remains contested. If crop pollination is used to argue for biodiversity conservation, clear distinction should be made between values of managed- and wild pollination services. Current methods either under-estimate or over-estimate the pollination service value, and make use of criticised general insect and managed pollinator dependence factors. We apply the theoretical concept of ascribing a value to a service by calculating the cost to replace it, as a novel way of valuing wild and managed pollination services. Adjusted insect and managed pollinator dependence factors were used to estimate the cost of replacing insect- and managed pollination services for the Western Cape deciduous fruit industry of South Africa. Using pollen dusting and hand pollination as suitable replacements, we value pollination services significantly higher than current market prices for commercial pollination, although lower than traditional proportional estimates. The complexity associated with inclusive value estimation of pollination services required several defendable assumptions, but made estimates more inclusive than previous attempts. Consequently this study provides the basis for continued improvement in context specific pollination service value estimates.

Genome-Wide Analysis of Natural Selection on Human Cis-Elements:

It has been speculated that the polymorphisms in the non-coding portion of the human genome underlie much of the phenotypic variability among humans and between humans and other primates. If so, these genomic regions may be undergoing rapid evolutionary change, due in part to natural selection. However, the non-coding region is a heterogeneous mix of functional and non-functional regions. Furthermore, the functional regions are comprised of a variety of different types of elements, each under potentially different selection regimes. Using the HapMap and Perlegen polymorphism data that map to a stringent set of putative binding sites in human proximal promoters, we apply the Derived Allele Frequency distribution test of neutrality to provide evidence that many human-specific and primate-specific binding sites are likely evolving under positive selection. We also discuss inherent limitations of publicly available human SNP datasets that complicate the inference of selection pressures. Finally, we show that the genes whose proximal binding sites contain high frequency derived alleles are enriched for positive regulation of protein metabolism and developmental processes. Thus our genome-scale investigation provides evidence for positive selection on putative transcription factor binding sites in human proximal promoters.

Fast Inhibition of Glutamate-Activated Currents by Caffeine:

Caffeine stimulates calcium-induced calcium release (CICR) in many cell types. In neurons, caffeine stimulates CICR presynaptically and thus modulates neurotransmitter release. Using the whole-cell patch-clamp technique we found that caffeine (20 mM) reversibly increased the frequency and decreased the amplitude of miniature excitatory postsynaptic currents (mEPSCs) in neocortical neurons. The increase in mEPSC frequency is consistent with a presynaptic mechanism. Caffeine also reduced exogenously applied glutamate-activated currents, confirming a separate postsynaptic action. This inhibition developed in tens of milliseconds, consistent with block of channel currents. Caffeine (20 mM) did not reduce currents activated by exogenous NMDA, indicating that caffeine block is specific to non-NMDA type glutamate receptors. Caffeine-induced inhibition of mEPSC amplitude occurs through postsynaptic block of non-NMDA type ionotropic glutamate receptors. Caffeine thus has both pre and postsynaptic sites of action at excitatory synapses.

Effect of Pictorial Depth Cues, Binocular Disparity Cues and Motion Parallax Depth Cues on Lightness Perception in Three-Dimensional Virtual Scenes:

Surface lightness perception is affected by scene interpretation. There is some experimental evidence that perceived lightness under bi-ocular viewing conditions is different from perceived lightness in actual scenes but there are also reports that viewing conditions have little or no effect on perceived color. We investigated how mixes of depth cues affect perception of lightness in three-dimensional rendered scenes containing strong gradients of illumination in depth. Observers viewed a virtual room (4 m width×5 m height×17.5 m depth) with checkerboard walls and floor. In four conditions, the room was presented with or without binocular disparity (BD) depth cues and with or without motion parallax (MP) depth cues. In all conditions, observers were asked to adjust the luminance of a comparison surface to match the lightness of test surfaces placed at seven different depths (8.5-17.5 m) in the scene. We estimated lightness versus depth profiles in all four depth cue conditions. Even when observers had only pictorial depth cues (no MP, no BD), they partially but significantly discounted the illumination gradient in judging lightness. Adding either MP or BD led to significantly greater discounting and both cues together produced the greatest discounting. The effects of MP and BD were approximately additive. BD had greater influence at near distances than far. These results suggest the surface lightness perception is modulated by three-dimensional perception/interpretation using pictorial, binocular-disparity, and motion-parallax cues additively. We propose a two-stage (2D and 3D) processing model for lightness perception.

Fake News Shows Don’t Teach Viewers Much About Political Issues, Study Finds:

A new study suggests that entertainment news shows such as The Daily Show or The Colbert Report may not be as influential in teaching voters about political issues and candidates as was previously thought.

Discovery Challenges Fundamental Tenet Of Cancer Biology:

Yale researchers have identified an unusual molecular process in normal tissues that causes RNA molecules produced from separate genes to be clipped and stitched together.

Memory Enhanced By Sports-cheat Drug:

A drug used to increase blood production in both medical treatments and athletic doping scandals seems also to improve memory in those using it. New research shows that the memory enhancing effects of erythropoietin (EPO) are not related to its effects on blood production but due to direct influences on neurons in the brain.

‘Water Bears’ Able To Survive Exposure To Vacuum Of Space:

Of all environments, space must be the most hostile: It is freezing cold, close to absolute zero, there is a vacuum, so no oxygen, and the amount of lethal radiation from stars is very high. This is why humans need to be carefully protected when they enter this environment.

Childbirth Was Already Difficult For Neanderthals:

Neanderthals had a brain at birth of a similar size to that of modern-day babies. However, after birth, their brain grew more quickly than it does for Homo sapiens and became larger too. Nevertheless, the individual lifespan ran just as slowly as it does for modern human beings.

Fluctuations In Serotonin Transport May Explain Winter Blues:

Why do many Canadians get the winter blues? In the first study of its kind in the living human brain, Dr. Jeffrey Meyer and colleagues at the Centre for Addiction and Mental Health (CAMH) have discovered greater levels of serotonin transporter in the brain in winter than in summer.

Dogs And Cats Can Live In Perfect Harmony In The Home, If Introduced The Right Way:

Thinking about adopting a perky little puppy as a friend for your fluffy cat, but worried that they’ll fight — well, like cats and dogs? Think again. New research at Tel Aviv University, the first of its kind in the world, has found a new recipe for success. According to the study, if the cat is adopted before the dog and if they are introduced when still young (less than 6 months for kittens, a year for dogs), there is a high probability that your two pets will get along swimmingly.

Marijuana Ingredients Show Promise In Battling Superbugs:

Substances in marijuana show promise for fighting deadly drug-resistant bacterial infections, including so-called “superbugs,” without causing the drug’s mood-altering effects, scientists in Italy and the United Kingdom are reporting.

Can Science Improve Man’s Best Friend?:

If you could design the perfect dog, what would it look like? Tall, short, fluffy, wiry, black, white, tan or brindle? While animal buyers often look closely at physical characteristics, behavioural traits can make the difference between a dog becoming a much loved and pampered family member, or a mistreated or neglected unwanted animal.

Lightweight And Long-legged Males Go The Distance For Sex:

Finding a mate can take considerable legwork as recently illustrated by the flightless and nocturnal Cook Strait giant weta Deinacrida rugosa. This cricket relative is found in New Zealand and is one of the world’s heaviest insects with females weighing in at 20 g, averaging twice the size of males.

Tracking The Reasons Many Girls Avoid Science And Math:

Most parents and many teachers believe that if middle-school and high-school girls show no interest in science or math, there’s little anyone can do about it. New research by a team that includes vocational psychologists at the University of Wisconsin-Milwaukee (UWM) indicates that the self-confidence instilled by parents and teachers is more important for young girls learning math and science than their initial interest.

The Beatles Show Link Between Positive Experiences And How Memories Are Shaped:

Results have just been announced for the Magical Memory Tour, the largest ever international online survey which asked people to blog their memories of the Beatles to create the biggest database of autobiographical memories ever attempted. The survey aimed to enhance our understanding of human memory by uncovering the role The Beatles and their music play in our personal histories. It was devised by psychologists Professor Martin Conway and Dr Catriona Morrison from the Institute of Psychological Sciences at the University of Leeds, who will be discussing their findings as part of the BA Festival of Science in Liverpool.

Ecologists Search For Invasive Ladybird’s Weak Spot:

Ecologists have discovered that — as well as being larger, hungrier and more aggressive than most British native ladybirds — the invasive alien harlequin ladybird is also more resistant to fungal disease and a parasitic wasp, two common natural enemies of native ladybirds.

Birds’ Harmonious Duets Can Be ‘Aggressive Audio Warfare,’ Study Finds:

Researchers reporting in the September 4th Current Biology, have new insight into the motivating factors that drive breeding pairs of some tropical bird species to sing duets. Those duets can be so closely matched that human listeners often mistake them for solos.

There are 11 new articles in PLoS ONE today. As always, you should rate the articles, post notes and comments and send trackbacks when you blog about the papers. Here are my own picks for the week – you go and look for your own favourites:

Continue reading →

Long-held Assumptions Of Flightless Bird Evolution Challenged By New Research:

Large flightless birds of the southern continents – African ostriches, Australian emus and cassowaries, South American rheas and the New Zealand kiwi – do not share a common flightless ancestor as once believed. Instead, each species individually lost its flight after diverging from ancestors that did have the ability to fly, according to new research conducted in part by University of Florida zoology professor Edward Braun.

Artificial Meadows And Robot Spiders Reveal Secret Life Of Bees:

Many animals learn to avoid being eaten by predators. Now ecologists have discovered that bumblebees can even learn to outwit colour-changing crab spiders. Bumblebees learn to avoid camouflaged predators by sacrificing foraging speed for predator detection, according to scientists from Queen Mary, University of London.

Sexologists Can Infer A Woman’s History of Orgasms By The Way She Walks:

A new study found that trained sexologists could infer a woman’s history of vaginal orgasm by observing the way she walks. The study is published in The Journal of Sexual Medicine.

What A Sleep Study Can Reveal About Fibromyalgia:

Research engineers and sleep medicine specialists from two Michigan universities have joined technical and clinical hands to put innovative quantitative analysis, signal-processing technology and computer algorithms to work in the sleep lab. One of their recent findings is that a new approach to analyzing sleep fragmentation appears to distinguish fibromyalgia patients from healthy controls.

Social Psychology Can Be Used To Understand Nuclear Restraint:

Social psychology is the study of how people and groups interact. A new study shows how social psychology can help us better understand the puzzle of nuclear restraint and uses the case of Japan to illustrate social psychology on nuclear decision-making.

No Connection Between Measles, Mumps, Rubella (MMR) Vaccine And Autism, Study Suggests:

In a case-control study, the presence of measles virus RNA was no more likely in children with autism and GI disturbances than in children with only GI disturbances. Furthermore, GI symptom and autism onset were unrelated to MMR vaccine timing.

A Virtuous Cycle: Safety In Numbers For Bicycle Riders:

It seems paradoxical but the more people ride bicycles on our city streets, the less likely they are to be injured in traffic accidents.

Rattlesnake-type Poisons Used By Superbug Bacteria To Beat Our Defenses:

Colonies of hospital superbugs can make poisons similar to those found in rattlesnake venom to attack our bodies’ natural defences, scientists heard September 8, 2008) at the Society for General Microbiology’s Autumn meeting being held at Trinity College, Dublin.