Engineered spider toxin could be the future of anti-venom vaccines.


New engineered spider protein could be the start of a new generation of anti-venom vaccines, potentially saving thousands of lives worldwide. The new protein, created from parts of a toxin from the reaper spider, is described today in the journal Vaccine.

The researchers behind the study, from the Universidade Federal de Minas Gerais in Brazil, say that the engineered protein may be a promising candidate for developing therapeutic serums or vaccines against other venoms.

Reaper spiders, or brown spiders, are a family of species found all over the world that produce harmful venoms. The toxic bite of these spiders causes skin around the bite to die, and can lead to more serious effects likekidney failure and haemorrhaging. TheseLoxosceles spiders are most prevalent in Brazil, where they cause almost 7,000 human accidents every year.

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The new study describes an engineered protein made of three pieces of a venom toxinfrom the Loxosceles intermedia spider. The engineered protein is not itself toxic, and gives effective protection against the effects of the pure spider venom in animal models.

“In Brazil we see thousands of cases of people being bitten by Loxosceles spiders, and the bites can have very serious side-effects,” said Dr. Chávez-Olortegui, corresponding author of the study. “Existing anti-venoms are made of the pure toxins and can be harmful to people who take them. We wanted to develop a new way of protecting people from the effects of these spider bites, without having to suffer from side-effects.”

Current approaches to protecting against venom involve giving the venom to animals, and taking the resulting antibodies for the serum. These antibodies enable the human immune system to prepare to neutralize venom from bites. Although they are somewhat effective, the production of anti-venoms like these is problematic because animals are required to produce them, and these animals suffer from the effects of the venom.

The new protein is engineered in the lab, without the need for the venomous animals. It is made up of three proteins, so it can protect against more than one kind of toxin at a time. The protein is not harmful to the immunized animal that produces the antibodies. It is also more effective than existing approaches, and easier to produce than preparing crude venom from spiders.

“It’s not easy taking venom from a spider, a snake or any other kind of venomous animal,” said Chávez-Olortegui. “With our new method, we would be able to engineer the proteins in the lab without having to isolate whole toxins from venom. This makes the whole process much safer.”

The researchers tested their new protein on rabbits: all immunized animals showed an immune response similar to the way they respond to the whole toxin. The engineered protein was effective for venom of the L. intermedia and L. gaucho sub-species, which have similar toxins. Immunized rabbits were protected from skin damage at the site of venom injection, and from haemorrhaging.

This engineered protein may be a promising candidate for therapeutic serum development or vaccination in the future.

 

Source: http://medicalxpress.com

Captured in silken netting and sticky hairs.


The great ecological success of spiders is often substantiated by the evolution of silk and webs. Biologists of the Kiel University and the University of Bern now found an alternative adaptation to hunting prey: hairy adhesive pads, so called scopulae. The scientists published their results in the May issue of the scientific journal PLoS One.
“More than half of all described spider species have abandoned building webs. They seize their prey directly and have to be able to hold and control the struggling prey without getting hurt themselves”, explains Jonas Wolff, PhD student in the working group ‘Functional Morphology and Biomechanics’. But how do these spiders manage to capture their prey, Wolff and his coworkers Professor Stanislav Gorb, Kiel, and Professor Wolfgang Nentwig, Bern, wondered. In order to find out, they turned their attention to the hairy pads, that grow on the legs of hunting spiders. These pads consist of specialized hairs (setae), which split into numerous branches. With these the setae can cling to surfaces very closely, which is necessary to exploit intermolecular adhesive forces.

„Until now, scientists assumed that the spiders mainly use those sticky pads for climbing on smooth surfaces. The earlier hypothesis that the adhesive pads are important for prey retention received scant attention. Our results show, that abandon web building occurred independently for several times. Interestingly, it was often accompanied by the evolution of similar adhesive pads. Specialized foot pads, which enable the spider to climb steep smooth surfaces such as window panes, are further developments derived from the prey capture apparatus”, Wolff explains. “These results give us entirely new insights on the evolution of spiders.”

Original publication:
Wolff, J. O., Nentwig, W. and Gorb, S. N. The great silk alternative: Multiple co-evolution of web loss and sticky hairs in spiders. PLoS ONE, In Press.
http://dx.plos.org/10.1371/journal.pone.00626

For Spiders, It’s Cruel to Be Kind.


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It turns out nice guys do finish last, at least among arachnids. A 6-year study of a New World spider reveals that although colonies composed of docile individuals fare better in the short term, their passive behavior ultimately does them in. A species may need a mean personality to keep from going extinct, the results suggest.

Not all spiders earn their frightening reputations. Even within a single species, some individuals are much mellower than others. Take the social spider Anelosimus studiosus, a native of North and South American forests that builds collective webs that house 40 to 100 individuals. In 2005, ecologists discovered that not all A. studiosus had the same disposition. When two spiders shared a container overnight, docile animals remained beside each other the whole time, whereas aggressive ones attacked each other and then moved to opposite corners. Jonathan Pruitt, an ecologist at the University of Pittsburgh in Pennsylvania, wondered which personality was more successful in the wild.

To find out, Pruitt performed personality tests on dozens of A. studiosus spiders and then arranged them into 90 couples consisting of an aggressive pair, a docile pair, or an aggressive spider matched with a docile one. The arachnids’ personalities are heritable, so a docile pair produces almost exclusively docile offspring, aggressive mates mainly make aggressive offspring, and mixed pairs produce a combination of docile and aggressive babies. After 1 week in the lab, each of the pairs had created small webs, or nests, on chicken wire within separate containers.

Pruitt returned to the Tennessee woods where he originally collected the spiders and wired each of the 90 nests onto trees and shrubs. For the next 5 years, he removed other species of spiders from the territory surrounding half of the webs. These 45 webs served as a control to test the hypothesis that disposition matters when hungry, solitary spiders abound in nature. The colonies in these well-maintained territories faired roughly the same as one another between 2007 and 2012, no matter the personality of their founders.

In contrast, colonies in the areas that were open to invaders differed from one another over time as solitary spiders began to infest the webs. Colonies founded by aggressive spiders successfully fought the intruders off, but produced fewer offspring because of the continuous conflict. In contrast, the predominantly docile colonies ignored intruders and continued to reproduce. In 2009, the docile colonies were flourishing, and their offspring had begun three times as many new colonies on nearby trees and shrubs compared with offspring from aggressive communities. Yet by 2010, the docile spiders’ apparent advantage began to wane as invaders increasingly ate them and stole the insects snagged by the colonies’ webs. By 2012, not a thread remained from the webs established by docile pairs, and only a quarter of those started by mixed pairs were left. Meanwhile,three-quarters of the original 15 nests founded by aggressive pairs stood strong, the team reports today inEcology Letters.

In nature, A. studiosus colonies consist of a mix of docile and aggressive individuals. In short-term studies, Pruitt says, aggressive spiders appear to be troublemakers because they often brawl with members of their own group. However, this study showed their importance when it comes to defense. “Originally, I thought aggressive spiders exploited docile ones, but now I see that the aggressive ones catch most of the food and take care of the society,” he says. Without aggressive spiders to care for them, docile spiders would go extinct whenever other spiders abound. Pruitt speculates that docile behavior still exists because it is useful to the colony in small doses. Perhaps docile individuals provide better care to hatchlings, he says.

For these spiders, passivity represents an “evolutionary dead end” because it comes with quick payoffs but dooms the lineage over time, Pruitt says. Much of the evidence for dead-end strategies comes from mathematical models that predict extinction after a tipping point, but this study documents such a strategy in action and defines the conditions that lead to a lineage’s demise. “The tipping point occurs when invaders are abundant,” Pruitt says. “Without them, colonies founded by docile individuals would flourish, but with them, they succumb to extinction.” The results from this study suggest something about aggression in general, Pruitt adds. “Species without defense might be driven to extinction by enemies”.

“This is a great, robust study that takes the study of animal temperament—which is kind of narrow—and puts it into a broad evolutionary framework,” says James Traniello, a behavioral ecologist at Boston University. “The whole idea of evolutionary dead-end strategies is poorly understood,” he says. A number of studies, such as those on Darwin’s finches, document how species diversify in real time, Traniello says, “and here we have a study that shows what goes on at the opposite side, how lineages decline.”

Source: sciencemag.org

Cold-tolerant wasp spiders spread to northern Europe.


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Temperature tolerance is key to the spread of wasp spiders into northern Europe, according to scientists.

Since the 1930s the distinctive spiders have expanded their range from the Mediterranean coast to Norway.

Researchers in Germany traced the population boom to breeding between the native European spiders and an isolated colony living near the Black Sea.

Molecular Ecology reports the genetic mixing resulted in generations rapidly adapting to living in colder climates.

Wasp spiders (Argiope bruennichi) are commonly named for their bright, striped abdomens and were recently recorded by the Woodland Trust in Usk, south Wales for the first time.

The first official records of this conspicuous species in the UK were made in the 1920s.

Henrik Krehenwinkel from the Max Planck Institute for Evolutionary Biology, Germany, analysed the DNA of spiders caught across their current range, and museum specimens to understand more about their evolutionary history.

Piecing together the genetic puzzle, he found that the spiders diverged after the last ice age: part of the population stayed on the Mediterranean while a colony headed east to Central Asia.

While these eastern populations adapted to live in climates as diverse as the tropical south of Japan and cold south-eastern Siberia, the spiders in the Mediterranean remained limited to warm areas.

But, according to the research, rising temperatures across the continent in the last century allowed the Mediterranean spiders to join up and breed with a previously isolated Black Sea population.

“This possibly restored genetic variation within a few generations and allowed for rapid adaptation,” said Mr Krehenwinkel.

He theorised that the novel combination of genes resulted in new physical characteristics that helped spiders to survive in different environments.

Out in the cold

To test the whether these more northerly spiders adapted a different temperature tolerance than Mediterranean populations, the PhD student analysed how they reacted when moved into one another’s habitats.

Southern spiders could not survive the freezing temperatures in the north, and their counterparts suffered from heat stress in the south.

Mr Krehenwinkel explained that the eastern population had adapted to cooler temperatures and this was passed on to European spiders in the population boom.

The result was the rapid adaptation of hardier offspring that could settle further north than their predecessors.

The spiders found in northern Europe have smaller bodies and are not seen in the coldest months of the year.

Scientists attribute both traits to seasonal changes which do not affect southern species. Spiders found in northern Europe “overwinter”, meaning their young are buried during the coldest months; emerging in spring.

The spiders then have limited warm months in which they can mature, which restricts how large they can grow before they reproduce in the autumn and the cycle begins again.

Mr Krehenwinkel described the hatchlings as “highly dispersive”, commenting that they can cover huge distances via a method known as “ballooning”: riding the breeze on a special parachute made of gossamer silk threads.

“By aerial dispersal, little spiders can cover distances of several hundred kilometres,” he told BBC Nature.

“Members of different genetic lineages can thus quickly track warming climate, which increases the likelihood of contact.”

Source:BBC