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Archive - Oct 7, 2015

Stem-Cell-Derived Cone Cells Growing to Confluence Form Organized Retinal Tissue 150 Microns Thick; Never Achieved Before; Might Enable Transplants to Treat Age-Related Macular Degeneration (ARMD)

Age-related macular degeneration (ARMD) could be treated by transplanting photoreceptors produced by the directed differentiation of stem cells, thanks to findings published online on October 6, 2015 in the journal Development by Professor Gilbert Bernier of the University of Montreal and its affiliated Maisonneuve-Rosemont Hospital, together with colleagues. The article is titled “Differentiation of Human Embryonic Stem Cells into Cone Photoreceptors through Simultaneous Inhibition of BMP, TGFβ, and Wnt Signaling.” Dr. Bernier is Director of the Stem Cell and Developmental Biology Laboratory at Maisonneuve-Rosemont Hospital and a Professor with the Department of Neuroscience and the Department of Opthalmology at the University of Montreal. ARMD is a common eye problem caused by the loss of cone cells. Dr. Bernier's team has developed a highly effective in vitro technique for producing light-sensitive retina cells from human embryonic stem cells. "Our method has the capacity to differentiate 80% of the stem cells into pure cones," Dr. Gilbert explained. "Within 45 days, the cones that we allowed to grow towards confluence spontaneously formed organized retinal tissue that was 150 microns thick. This has never been achieved before." In order to verify the technique, Dr. Bernier injected clusters of retinal cells into the eyes of healthy mice. The transplanted photoreceptors migrated naturally within the retina of their host. "Cone transplant represents a therapeutic solution for retinal pathologies caused by the degeneration of photoreceptor cells," Dr. Bernier explained.

48-Million-Year-Old Fossil of Horse-Like Fetus Analyzed; Material Included Preserved Soft Tissue Like the Uteroplacenta and One Broad Uterine Ligament; May Be Earliest Fossil Record of Uterine System of Placental Mammal

Analysis of a 48-million-year-old fossil of a horse-like equoid fetus discovered, together with the fossil of its mother, in 2000 at the Messel pit near Frankfurt, Germany, is reported in a study published online on October 7, 2015 in the open-access journal PLOS ONE. The report was authored by Jens Lorenz Franzen, Ph.D., from Senckenberg Research Institute in Frankfurt, Germany, and also from the Naturhistorisches Museum in Basel, Switzerland, together with colleagues. The article is titled “Description of a Well Preserved Fetus of the European Eocene Equoid Eurohippus messelensis.” The authors of this study completed their investigation of the fetus from a 48-million-year-old horse-like equoid uncovered near Frankfurt, Germany, in 2000. They evaluated the bones and anatomy and used scanning electronic microscopy (SEM) and high-resolution micro-x-ray technologies to describe the ~12.5 cm fetus. The fetus appears to be well-preserved, with almost all bones present and connected, except for the skull, which appears to have been crushed. The well-preserved condition of the fossil allowed the researchers to reconstruct the original appearance and position of the fetus. They estimate that the mare may have died shortly before birth, but they don't believe the death was related to birth. The authors also found preserved soft tissue, like the uteroplacenta and one broad uterine ligament, which may represent the earliest fossil record of the uterine system of a placental mammal. Applying SEM, the authors discovered a bacterial lawn replacing the soft tissues, as is common with other specimens found in that area. The observable details correspond largely with living mares, which lead the authors to posit that the reproductive system was already highly developed during the Paleocene era, and possibly even earlier.

Fluid on Feet of Insects May Enhance Ability to Quickly Release the Foot, Rather Than Enhancing Adhesion; Understanding How Insects Control Adhesion & Release May Have Broader Implications

Geckos, tree frogs, spiders, and insects all share a special skill - they can walk up vertical surfaces and even upside down using adhesive pads on their feet. But geckos have “dry” feet, while insects have “wet” feet. Scientists have assumed that the two groups use different mechanisms to keep their feet firmly attached to a surface, but new research from David Labonte and Walter Federle, Ph.D., in the University of Cambridge's Department of Zoology provides evidence that this is not actually the case. "It has generally been assumed that the fluid on their feet must be involved in helping insects like stick insects adhere to a surface by capillary and viscous forces, in the same way that a beer glass will stick to a glass table if it's wet on the bottom," explains Labonte, lead author of the study published online on September 10, 2015 in Soft Matter, from the Royal Society of Chemistry, "but our research shows that the fluid is likely used for something else entirely; it may even help insects unstick their feet." The Soft Matter article is titled “'Rate-Dependence of 'Wet' Biological Adhesives and the Function of the Pad Secretion in Insects.” By measuring how much force was required to detach the foot of a stick insect from a glass plate at different speeds and applying the theory of fracture mechanics, Labonte and Dr. Federle found that only a “dry” contact model could explain the data. They also carried out a comparison of the sticking performance of wet and dry adhesive pads, which revealed that there is a striking lack of differences between the two, contrary to previous opinion.Insects and geckos need to walk up vertical surfaces and even upside down in order to get to the places where they feed and to escape from predators.

High-Arctic Butterflies Shrink with Rising Temperatures; Metabolic Rate Increases, Outstripping Feeding Capacity and Leading to Smaller Body Size

New research shows that butterflies in Greenland have become smaller in response to increasing temperatures due to climate change. It has often been demonstrated that the ongoing rapid climate change in the Arctic region is causing substantial change to Arctic ecosystems. Now, Danish researchers demonstrate that a warmer Greenland could be bad for its butterflies, which are becoming smaller under warmer summers. Researchers from Aarhus University in Denmark have measured wing length of nearly 4,500 individuals collected annually between 1996 and 2013 from Zackenberg Research Station in Northeast Greenland, and found that wing length has decreased significantly in response to warmer summers and at the same rate for both species investigated. "Our studies show that males and females follow the same pattern and it is similar in two different species, which suggests that climate plays an important role in determining the body size of butterflies in Northeast Greenland," says Senior Scientist Toke T. Hoye, Ph.D., Aarhus Institute of Advanced Studies, Aarhus University. Only very few field studies have been able to follow changes in the body size of the same species over a period during which the climate has changed and this is the longest-known time series on body size variation in butterflies, of which the scientists are aware. Body size change in response to rising temperature is an anticipated response to climate change, but few studies have actually demonstrated it in the field. The response can go both ways; for some animal species, a longer feeding season results in increased body size, and for others, the changes in metabolism cause a net loss of energy which reduces the body size.

Mad Cow Disease Changed Diet of Spain’s Galician Wolf; Following Disease-Related EU Carcass Disposal Regulations, Wolves Moved from Primarily Feeding on Carrion to Preying More on Live Animals

The Creutzfeldt-Jakob prion-caused disease crisis in Europe was a turning point for the diet of the Galician wolf in Spain, which, until the year 2000, had primarily fed on the carrion of domestic animals. A new study shows that, after European health regulations made it illegal to abandon dead livestock, wolves started to consume more wild boars, roe deer, and wild ponies, and also began to attack more cattle ranches when faced with food shortages in certain areas. With the arrival of bovine spongiform encephalopathy - commonly known as mad cow disease - in Europe, the European Community had to enforce a number of laws in the year 2000 in order to prevent the disease from spreading. Among other things, it became illegal to abandon the carcasses of ruminants that had died on farms; up until then, this had been an important food source for wolves. From then on, having been adopted by every European country, this measure began to affect a number of scavenger species, especially the vultures that lived on the Iberian Peninsula. But they weren't the only victims; the Iberian wolf (Canis lupus signatus) was also affected. A team of researchers has analyzed the dietary evolution of Galician canines by examining two time periods: before the European law was established (from the '70s up to the year 2000) and afterwards (from 2003 to 2008). Besides this legislation, a combination of other changes also affected the wolves, such as reductions in the quantity of livestock, rural depopulation, and the reforestation of agricultural land, which boosted the number of wild ungulates. The new study, published in the October 2015 issue of Environmental Management, indicates two very different dietary patterns for the two time periods.

2015 Nobel Prize in Chemistry Awarded for Mechanistic Studies of DNA Repair; Tomas Lindahl, Paul Modrich, & Aziz Sancar Share Award

On Wednesday, October 7, the Royal Swedish Academy of Sciences announced that it had decided to award the Nobel Prize in Chemistry for 2015 to Tomas Lindahl (Sweden, UK), Paul Modrich (USA) and Aziz Sancar (Turkey, USA) for having mapped, at a molecular level, how cells repair damaged DNA and safeguard the genetic information. Their work has provided fundamental knowledge of how a living cell functions and is, for instance, used for the development of new cancer treatments. The monetary prize of $970,000 will be shared equally amongst the three new Nobel Laureates. Each day our DNA is damaged by UV radiation, free radicals, and other carcinogenic substances, but even without such external attacks, a DNA molecule is inherently unstable. Thousands of spontaneous changes to a cell’s genome occur on a daily basis. Furthermore, defects can also arise when DNA is copied during cell division, a process that occurs several million times every day in the human body. The reason our genetic material does not disintegrate into complete chemical chaos is that a host of molecular systems continuously monitor and repair DNA. The Nobel Prize in Chemistry 2015 awards three pioneering scientists who have mapped how several of these repair systems function at a detailed molecular level. In the early 1970s, scientists believed that DNA was an extremely stable molecule, but Tomas Lindahl, Ph.D., demonstrated that DNA decays at a rate that ought to have made the development of life on Earth impossible. This insight led him to discover a molecular machinery, base excision repair, which constantly counteracts the collapse of our DNA. Aziz Sancar, Ph.D., has mapped nucleotide excision repair, the mechanism that cells use to repair UV damage to DNA. People born with defects in this repair system will develop skin cancer if they are exposed to sunlight.