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Archive - Mar 2015

March 27th

Color of Bird Plumage Based on More Than Sexual Selection

In the world of bird fashion, the guys seem to have all the fun: brighter feathers, sharper accessories, more pizzazz. Researchers going back to Charles Darwin have focused on the contrast between the sexes, attributing the males' brighter colors to their need to attract mates. A group of researchers at University of Wisconsin-Milwaukee took a different approach, testing a hypothesis that evolution has actually resulted in similarities among the sexes as much as differences. Looking at nearly 1,000 species of birds, they found that while males often have brighter feathers than females, the two sexes have come closer together in color over time to blend into their surroundings and hide from predators. Natural selection - during migration, breeding in subtropical locales, and care of young - is as powerful as sexual selection. "Although most studies of bird plumage focus on dichromatism, evolutionary change has most often led to similar, rather than different, plumage in males and females," the authors write. Dr. Peter Dunn and Dr. Linda Whittingham, Professors of Biological Sciences at UW-Milwaukee, wrote the paper with Jessica Armenta, a former UW-Milwaukee graduate student who now teaches at Austin Community College in Texas. "Our study shows that ecology and behavior are driving the color of both sexes, and it is not due to sexual selection," they write. The open-access article, "Natural and Sexual Selection Act on Different Axes of Variation in Avian Plumage Color," was published online on March 27, 2015 in Science Advances. Ms. Armenta spent four years collecting data from 977 species of birds from six museums in the U.S. and Australia. She looked at six birds of each species, three males and three females. Dr. Dunn and Dr. Whittingham analyzed the data, assigning each bird a color score based on scales of brightness and hue.

March 27th

Hopkins Study Suggests Non-Dye-Based MRI Analysis of Cell-Surface Sugar Molecules Can Differentiate Cancer and Non-Cancer Cells

Imaging tests like mammograms or CT scans can detect tumors, but figuring out whether a growth is or isn't cancer usually requires a biopsy to study cells directly. Now results of a Johns Hopkins study suggest that MRI could one day make biopsies more effective or even replace them altogether by noninvasively detecting telltale sugar molecules shed by the outer membranes of cancerous cells. The MRI technique, so far tested only in test-tube-grown cells and mice, is described in a report published online on March 27, 2015 in an open-access article in Nature Communications. The article is titled “Label-Free in vivo Molecular Imaging of Underglycosylated Mucin-1 Expression in Tumor Cells.” "We think this is the first time scientists have found a use in imaging cellular slime," says Jeff Bulte, Ph.D., a Professor of Radiology and Radiological Science in the Institute for Cell Engineering at the Johns Hopkins University School of Medicine. "As cells become cancerous, some proteins on their outer membranes shed sugar molecules and become less slimy, perhaps because they're crowded closer together. If we tune the MRI to detect sugars attached to a particular protein, we can see the difference between normal and cancerous cells." Dr. Bulte's research builds on recent findings by others that indicate glucose can be detected by a fine-tuned MRI technique based on the unique way it interacts with surrounding water molecules without administering dyes. Other researchers have used MRI, but needed injectable dyes to image proteins on the outside of cells that lost their sugar. In this study, Dr. Bulte's research team compared MRI readings from proteins known as mucins, with and without sugars attached, to see how the signal changed.

New Immune-System-Based Biomarker Set from Europe May Be Used in Blood Test for Early Detection of Colon Cancer

Colorectal cancer is the third most common form of cancer globally and the second most common cause of cancer deaths. The chance of a cure is high if the cancer is detected early enough, but early detection is not a given. Researchers from VIB and KU Leuven - together with various European oncology centers, including UZ Leuven - have identified bio-markers that can be incorporated in a new diagnostic test. This should make it possible to detect colorectal cancer at an early stage using a simple blood test. The results were published online on March xx, 2015 in Gut in an article titled “Tumour-Educated Circulating Monocytes Are Powerful Candidate Biomarkers for Diagnosis and Disease Follow-Up of Colorectal Cancer.” Dr. Max Mazzone (VIB/KU Leuven) commented: “This research demonstrates how important it is to gain a thorough understanding of the role of our immune system in cancer. In this case, this knowledge will hopefully result in a new, more sensitive test to detect colorectal cancer at an early stage, so that more patients can be cured. I hope that we can soon find an industrial partner to help us achieve the following step, which is the development of the test.” In 2012, a total of 1.4 million people worldwide were diagnosed with colorectal cancer, this figure is expected to increase to 2.4 million by 2035. This is a condition that affects a growing number of people each year. Colorectal cancer is very treatable if it is detected at an early stage, with approximately 95% chance of a cure. If detected at a late stage, however, the chance of surviving 5 years after diagnosis is less than 10 %. Therefore, it is very important to be able to detect the disease in an early stage. And therein lies the rub.

Differently Colored Lettuces Have Antioxidants That Act at Different Speeds

Lettuce, one of the indispensable vegetables in the Mediterranean diet, is a food that greatly benefits health, mainly because it is rich in antioxidants. But not all lettuce varieties have the same antioxidant effect. According to a study led by the researcher Dr. Usue Pérez-López of the Department of Plant Biology and Ecology of the UPV/EHU's Faculty of Science and Technology (Universidad del Pais Vasco/Euskal Herriko Unibertsitatea or University of the Basque Country), the color of the leaves of these vegetables is an indicator of the speed at which their antioxidants act. So Lettuces with green leaves have antioxidants that react more slowly, while red-leaf lettuces have a faster effect. The results of this study have been set out in a paper titled "Phenolic Composition and Related Antioxidant Properties in Differently Colored Lettuces: A Study by Electron Paramagnetic Resonance (EPR) Kinetics" published online on November 11, 2014 in the Journal of Agricultural and Food Chemistry. Antioxidants provide long-term protection against the chain reactions of free radical processes, in other words, of the electron-charged highly reactive oxidizing molecules that are capable of causing cell damage and generating various diseases. Lettuce is rich in antioxidants, as it contains compounds like phenolic acids, flavonoids, anthocyanins, and vitamins A and C, among other antioxidants. To conduct this research, which began in 2011 and in which researchers of the UPV/EHU and the University of Pisa (Italy) have been participating, the compounds of three lettuce varieties were analyzed: the green-leaf “Batavia,” the semi-red-leaf “Marvel of Four Seasons,” and the red-leaf “Oak Leaf” (photo).

Gene Duplication Played Key Role in Evolution of Vertebrate Eye

A new study from SciLifeLab at Uppsala University in Sweden shows that genes crucial for vision were multiplied in the early stages of vertebrate evolution and acquired distinct functions leading to the sophisticated mechanisms of vertebrate eyes. One striking feature of vertebrates is the prominent role that vision plays in almost all major animal groups. The vertebrate eye has a unique organization and is known to have arisen at the time of the first vertebrates over 500 million years ago. A new study by the research team led by Dr. Xesús Abalo and Dr. Dan Larhammar explains how ancient gene duplications have played decisive roles in the evolution of novel functions. The first step in vision is the response to light by the cone and rod cells in the retina at the back of the eye. Twenty years ago, the first studies of the light receptors, proteins called opsins, in birds indicated that color vision arose before the dim light black-and-white vision provided by rods. This hypothesis was recently confirmed by detailed studies of opsin genes in a broad range of vertebrate species (David Lagman and Daniel Ocampo Daza in the team of Abalo & Larhammar, open-access, http://www.biomedcentral.com/1471-2148/13/238). The authors found that new opsin genes were generated when the genome of the vertebrate ancestor was doubled twice at the dawn of the vertebrates. These massive gene duplication events resulted in many novel functions, not only for vision, but also for many other characteristic vertebrate features. In the new study, Dr. Lagman and co-workers describe evolutionary changes in the first relay step in the vision cascade, mediated by a family of G-proteins called transducins. These trigger the cellular response by activating a critical enzyme.

March 26th

Rockefeller Scientists Use “Amazing” CRISPR-Cas9 Technique to Modify and Study Key Genes of Aedes aegypti Mosquito, Carrier of Chikungunya, Yellow Fever, and Dengue; Technique Is “Revolutionizing Biology,” Group Leader Vosshall Says

Traditionally, to understand how a gene functions, a scientist would breed an organism that lacks that gene - "knocking it out" - then ask how the organism has changed. Are its senses affected? Its behavior? Can it even survive? Thanks to the recent advance of gene editing technology, this gold standard genetic experiment has become much more accessible in a wide variety of organisms. Now, researchers at Rockefeller University have harnessed an increasingly popular molecular technique known as CRISPR-Cas9 editing (originally identified in bacteria as a natural defense mechanism that bacteria possess to recognize and disable viruses and plasmids by cutting up their genetic material) in an important and understudied species: the mosquito, Aedes aegypti (photo), which infects hundreds of millions of people annually with the viral diseases chikungunya, yellow fever, and dengue. Rockefeller researchers led by postdoctoral fellow Dr. Benjamin J. Matthews adapted the CRISPR-Cas9 system to Ae. aegypti and were able to efficiently generate targeted mutations and insertions in a number of genes. The immediate goal of this project, says Dr. Matthews, is to learn more about how different genes help the species operate so efficiently as a disease vector, and create new ways to control it. "To understand how the female mosquito actually transmits disease," says Dr. Matthews, "you have to learn how she finds humans to bite, and how she chooses a source of water to lay her eggs. Once you have that information, techniques for intervention will come."

Honey Bees Appear to Use Independent RNAi and Methylation Pathways in Anti-Viral Defense

Honey bees use different sets of genes, regulated by two distinct mechanisms, to fight off viruses, bacteria, and gut parasites, according to researchers at Penn State, the Georgia Institute of Technology, and the University of California, Davis. The findings may help scientists develop honey bee treatments that are tailored to specific types of infections. "Our results indicate that different sets of genes are used in immune responses to viruses versus other pathogens, and these anti-viral genes are regulated by two very distinct processes -- expression and DNA methylation," said David Galbraith, a graduate student in entomology at Penn State. The results were published online on March 26, 2015 in the open-access journal PLOS Pathogens. The article is titled “Parallel Epigenomic and Transcriptomic Responses to Viral Infection in Honey Bees (Apis mellifera).” According to Dr. Christina Grozinger, Director of the Penn State Center for Pollinator Research, beekeepers lose an average of 30 percent of their colonies every winter and an average of 25 percent in the summer. "Honey bees have more than 20 types of viruses, and several of them have been linked to losses of honey bee colonies," she said. "Yet, beekeepers currently do not have any commercially available methods to reduce viral infections." With a goal of uncovering which genes increase or decrease their activity in response to the presence of viruses, the researchers measured expression levels of all genes in the honey bee genome in both infected and uninfected bees. They found that the RNAi pathway had increased activity and, therefore, is likely an important anti-viral immune pathway in bees.

Young Girl Nearly Dies from Flu Infection Because of Mutations in Both Homologous Copies of IRF7 Gene for Interferon Amplification

Nobody likes getting the flu, but for some people, fluids and rest aren't enough. A small number of children who catch the influenza virus fall so ill they end up in the hospital -- perhaps needing ventilators to breathe -- even while their family and friends recover easily. New research by Rockefeller University scientists, published online on March 26, 2015 in Science, helps explain why: rare genetic mutations. The article is titled “Life-Threatening influenza and Impaired Interferon Amplification in Human IRF7 Deficiency.” The researchers scrutinized blood and tissue samples from a young girl who, at the age of two-and-a-half, developed acute respiratory distress syndrome after catching the flu, and ended up fighting for her life in the hospital. Years after her ordeal, which she survived, scientists led by Rockefeller’s Dr. Jean-Laurent Casanova discovered that it could be explained by rare mutations she carries that prevented her from producing a protein, interferon, that helps fight off the virus. "This is the first example of a common, isolated, and life-threatening infection of childhood that is shown to be also a genetic disease," says Dr. Casanova. The good news from these results, however, is that clinicians have a new treatment option for children who mysteriously develop severe cases of the flu. "This finding suggests that one could treat severe flu of childhood with interferon, which is commercially available," says Dr. Casanova, who is Professor and Head of the St. Giles Laboratory of Human Genetics of Infectious Disease at Rockefeller, as well as a Howard Hughes Medical Institute (HHMI) investigator. The fact that a child's genes could affect the severity of her illness wasn't a surprise to the members of Casanova's lab, who have been studying this phenomenon for decades.

Nanoparticle Delivery of FL2 Inactivator (siRNA) Cuts Wound-Healing Time in Half

An experimental therapy developed by researchers at Albert Einstein College of Medicine of Yeshiva University in New York City cut in half the time it takes to heal wounds compared to no treatment at all. Details of the therapy, which was successfully tested in mice, were published on March 10, 2015, online in the Journal of Investigative Dermatology. The title of the article is “Fidgetin-like 2: A Novel Microtubule-Based Regulator of Wound Healing." "We envision that our nanoparticle therapy could be used to speed the healing of all sorts of wounds, including everyday cuts and burns, surgical incisions, and chronic skin ulcers, which are a particular problem in the elderly and people with diabetes," said study co-leader David J. Sharp, Ph.D., Professor of Physiology & Biophysics at Einstein. Dr. Sharp and his colleagues had earlier discovered that an enzyme called fidgetin-like 2 (FL2) puts the brakes on skin cells as they migrate towards wounds to heal them. They reasoned that the healing cells could reach their destination faster if their levels of FL2 could be reduced. So the scientists developed a drug that inactivates the gene that makes FL2 and then put the drug in tiny gel capsules called nanoparticles and applied the nanoparticles to wounds on mice. The treated wounds healed much faster than untreated wounds. FL2 belongs to the fidgetin family of enzymes, which play varying roles in cellular development and function. To learn more about FL2's role in humans, Dr. Sharp suppressed FL2's activity in human cells in tissue culture. When those cells were placed on a standard wound assay (for measuring properties like cell migration and proliferation), they moved unusually fast. "This suggested that if we could find a way to target FL2 in humans, we might have a new way to promote wound healing," said Dr. Sharp.

Skin Microbiome May Offer Answers to Protecting Threatened Frogs from Lethal Fungus

A team of scientists including Virginia Tech researchers is one step closer to understanding how bacteria on a frog's skin affects the frog’s likelihood of contracting disease. A frog-killing fungus known as Batrachochytrium dendrobatidis, or Bd, has already led to the decline of more than 200 amphibian species, including the now-extinct-in-the-wild Panamanian golden frog. In a recent study, the research team attempted to apply beneficial bacteria found on the skin of various Bd-resistant wild Panamanian frog species to Panamanian golden frogs in captivity, to see if this would stimulate a defense against the disease. They found that, while the treatment with beneficial bacteria was not successful due to its inability to stick to the skin, there were some frogs that survived exposure to the fungus. These survivors actually had unique bacterial communities on their skin before the experiments started. The results were published online on March 18, 2015 in an open-access article in the Proceedings of the Royal Society B. The title of the article is “Composition of Symbiotic Bacteria Predicts Survival in Panamanian Golden Frogs Infected with a Lethal Fungus.” The next step is to explore these new bacterial communities. "We were disappointed that the treatment didn't work, but glad to have discovered new information about the relationship between these symbiotic microbial communities and amphibian disease resistance," said Dr. Lisa Belden, an Associate Professor of Biological Sciences in the College of Science, a Fralin Life Science Institute affiliate, and a faculty member with the new Global Change Center at Virginia Tech. "Every bit of information gets us closer to getting these frogs back into nature."