Tag Archives: Kiel University

Similarities between a moth’s eye and snakeskin

Finding patterns in nature that are repeated seems to be the order of the day although there is a twist to this particular story. This time, researchers at Kiel University (also known as, University of Kiel or Christian-Albrechts University of  Kiel [Germany]) have found superficial similarities between a moth’s eye and snakeskin according to a May 4, 2016 news item on Nanowerk,

One thing is obvious: moth’s eyes and snake’s skin are entirely different. Researchers at Kiel University have taken a closer look, however, and have now brought the supposed ‘apples and oranges’ to a common denominator. They have opened up a completely new, comparative view of biological surfaces using a newly developed method, and have thus come closer to the solution of how these surfaces work. Dr. Alexander Kovalev, Dr. Alexander Filippov and Professor Stanislav Gorb from the Zoological Institute at Kiel University have published their findings in the current edition of the scientific journal Applied Physics A (“Correlation analysis of symmetry breaking in the surface nanostructure ordering: case study of the ventral scale of the snake Morelia viridis”).

A May 3, 2016 Kiel University press release, which originated the news item, describes the scientists’ first approach to the research,

One surface demonstrates reduced light reflection, the other is water repellent and resistant to abrasion. Surfaces in the animal world are evolved to adapt to their environments and give the animal they cover the greatest possible evolutionary advantage. Scientists are today still puzzled by exactly how and why these different structures develop in detail.

Current research looks right into the surface nano-structures using the latest research techniques. Normally, we would limit ourselves to comparisons within closely related species and just look thoroughly at small areas of the surface, says Gorb: “That is why we asked ourselves which structural differences can be found between completely different species. To do so, we changed biology’s typical perspective and addressed larger surface areas from various species.” These types of cross-species or cross-material studies of nanostructures are common in other technical or inorganic fields. In Biology, however, this method is completely new, Gorb continues.

They got the idea from the decorations in the hallway of their own institute, where scanning electron microscope images of moth’s eyes and snake’s skin are displayed. At some point, theoretical physicist Filippov noticed similarities between the images, which showed the surfaces at a resolution of a few millionths of a millimetre. Nipples and dimples could be seen which seemed to the human eye to follow a certain pattern. Using methods that are normally used in crystallography, the scientists were finally able to recognise the particular patterns that distinguish the two species. “The structure of moth’s eyes is perfectly organised. Nipples are highly ordered, and preferred directions are exhibited in the structural organisation”, explains Kovalev, biophysicist and main author of the study. The scientists were already aware of the eye structure’s strict symmetry. However, the fact that this goes right through to the nano-level and is repeated across the entire surface in so-called domains, is an important new finding.

So which symmetry does snake’s skin have, which at first glance appears similar, perhaps even more perfectly organised? “Compared to the structure of the moth’s eye, the structure of the snake’s skin is unorganised”, explains Kovalev. He continued: “If we concentrate on one dimple in the skin, like one nipple in the eye, we only see a diffuse cloud of further dimples in the close surroundings. Neither particular directions nor the regular arrangement can be defined. This unorganised structure continues across the entire surface.”

On concluding there were significant differences as well as similarities, the scientists took a closer look,

On their own, these findings about the organised eye structure on the one hand and the unorganised skin structure on the other hand are not especially significant. But by taking the common denominator, i.e. investigating both structures with the same degree of resolution, it is possible for the first time to compare fundamentally different structures, explains Gorb: “However, the ‘coincidental’ degree of organisation is not coincidental, but a result of evolution. That would mean that the perfect organisation gives the moth its incredible night vision, while the imperfect organisation in snake’s skin ensures the best friction properties.” That sounds logical, when you consider the laws of physics, that a symmetrical structure is necessary for good vision and good friction properties require the surface ordering in the contact with the ground to be as low as possible.

If the Kiel-based researchers had followed the usual approaches and compared snakes to snakes and moths to moths, the organisation of the elements at nano-level would have hardly been considered significant. “By comparing evolutionary distant species, we now see that the key to understanding surface functions must be right at the smallest level. Every biological surface is adapted to its environment, and these adaptations are reflected in the organisation of their smallest elements in a certain perfect or imperfect degree”, Gorb concludes.

This is the snakeskin,

Scanning electron microscopy image of the tail ventral scale in the snake Morelia viridis. The black shadowed gray circle marks a typical hexagonal arrangement of dimples, whereas both white and black circles mark five- and sevenfold symmetrical arrangement of dimples, respectively. Credit: research group Gorb

Scanning electron microscopy image of the tail ventral scale in the snake Morelia viridis. The black shadowed gray circle marks a typical hexagonal arrangement of dimples, whereas both white and black circles mark five- and sevenfold symmetrical arrangement of dimples, respectively. Credit: research group Gorb

This is the moth’s eye,

 

Scanning electronmicroscopy image of a single ommatidium surface of an eye in the moth Manduca sexta. Credit: research group Gorb

Scanning electronmicroscopy image of a single ommatidium surface of an eye in the moth Manduca sexta.
Credit: research group Gorb

Here’s a link to and a citation for the paper,

Correlation analysis of symmetry breaking in the surface nanostructure ordering: case study of the ventral scale of the snake Morelia viridis by A. Kovalev, A. Filippov, S. N. Gorb. Applied Physics A March 2016, 122:253 DOI:  10.1007/s00339-016-9795-2 First online: 03 March 2016

This paper is behind a paywall.

Possible nanoparticle-based vaccine/microbiocide for herpes simplex virus-2

An April 27, 2016 news item on ScienceDaily describes a new therapeutic and preventative technology for herpes,

An effective vaccine against the virus that causes genital herpes has evaded researchers for decades. But now, researchers from the University of Illinois at Chicago [UIC] working with scientists from Germany have shown that zinc-oxide nanoparticles shaped like jacks can prevent the virus from entering cells, and help natural immunity to develop.

“We call the virus-trapping nanoparticle a microbivac, because it possesses both microbicidal and vaccine-like properties,” says corresponding author Deepak Shukla, professor of ophthalmology and microbiology & immunology in the UIC College of Medicine. “It is a totally novel approach to developing a vaccine against herpes, and it could potentially also work for HIV and other viruses,” he said.

The particles could serve as a powerful active ingredient in a topically-applied vaginal cream that provides immediate protection against herpes virus infection while simultaneously helping stimulate immunity to the virus for long-term protection, explained Shukla.

An April 27, 2016 UIC news release (also on EurekAlert), which originated the news item, provides more context for the work,

Herpes simplex virus-2, which causes serious eye infections in newborns and immunocompromised patients as well as genital herpes, is one of the most common human viruses. According to the Centers for Disease Control and Prevention, about 15 percent of people from ages 14-49 carry HSV-2, which can hide out for long periods of time in the nervous system. The genital lesions caused by the virus increase the risk for acquiring human immunodeficiency virus, or HIV.

“Your chances of getting HIV are three to four times higher if you already have genital herpes, which is a very strong motivation for developing new ways of preventing herpes infection,” Shukla said.

Treatments for HSV-2 include daily topical medications to suppress the virus and shorten the duration of outbreaks, when the virus is active and genital lesions are present. However, drug resistance is common, and little protection is provided against further infections. Efforts to develop a vaccine have been unsuccessful because the virus does not spend much time in the bloodstream, where most traditional vaccines do their work.

The news release goes on to provide technical details,

The tetrapod-shaped zinc-oxide nanoparticles, called ZOTEN, have negatively charged surfaces that attract the HSV-2 virus, which has positively charged proteins on its outer envelope. ZOTEN nanoparticles were synthesized using technology developed by material scientists at Germany’s Kiel University and protected under a joint patent with UIC.

When bound to the nanoparticles, HSV-2 cannot infect cells. But the bound virus remains susceptible to processing by immune cells called dendritic cells that patrol the vaginal lining. The dendritic cells “present” the virus to other immune cells that produce antibodies. The antibodies cripple the virus and trigger the production of customized killer cells that identify infected cells and destroy them before the virus can take over and spread.

The researchers showed that female mice swabbed with HSV-2 and an ointment containing ZOTEN had significantly fewer genital lesions than mice treated with a cream lacking ZOTEN. Mice treated with ZOTEN also had less inflammation in the central nervous system, where the virus can hide out.

The researchers were able to watch immune cells pry the virus off the nanoparticles for immune processing, using high-resolution fluorescence microscopy.

“It’s very clear that ZOTEN facilitates the development of immunity by holding the virus and letting the dendritic cells get to it,” Shukla said.

If found safe and effective in humans, a ZOTEN-containing cream ideally would be applied vaginally just prior to intercourse, Shukla said. But if a woman who had been using it regularly missed an application, he said, she may have already developed some immunity and still have some protection. Shukla hopes to further develop the nanoparticles to work against HIV, which like HSV-2 also has positively charged proteins embedded in its outer envelope.

ZOTEN particles are uniform in size and shape, making them attractive for use in other biomedical applications. The novel flame transport synthesis technology used to make them allows large-scale production, said Rainer Adelung, professor of nanomaterials at Kiel University. And, because no chemicals are used, the production process is green.

Adelung hopes to begin commercial production of ZOTEN through a startup company that will be run jointly with his colleagues at UIC.

Here’s an image of the particles, courtesy of UIC,

Zinc oxide tetrapod nanoparticles. Credit: Deepak Shukla

Zinc oxide tetrapod nanoparticles. Credit: Deepak Shukla

Here’s a link to and a citation for the paper,

Intravaginal Zinc Oxide Tetrapod Nanoparticles as Novel Immunoprotective Agents against Genital Herpes by Thessicar E. Antoine, Satvik R. Hadigal, Abraam M. Yakoub, Yogendra Kumar Mishra, Palash Bhattacharya, Christine Haddad, Tibor Valyi-Nagy, Rainer Adelung, Bellur S. Prabhakar, and Deepak Shukla. The Journal of Immunology April 27, 2016 1502373  doi: 10.4049/jimmunol.1502373 Published online before print April 27, 2016

This paper is behind a paywall.

One final comment, it’s a long from a mouse vagina in this study to a human one.