Ad Zone

Share |

Tuesday, September 13, 2011

Are sharks color blind?

Sharks are unable to distinguish colors, even though their close relatives rays and chimaeras have some color vision, according to new research by Dr. Nathan Scott Hart and colleagues from the University of Western Australia and the University of Queensland in Australia. Their study shows that although the eyes of sharks function over a wide range of light levels, they only have a single long-wavelength-sensitive cone* type in the retina and therefore are potentially totally color blind. Hart and team's findings are published online in Springer's journal Naturwissenschaften – The Science of Nature.

"This new research on how sharks see may help to prevent attacks on humans and assist in the development of fishing gear that may reduce shark bycatch in long-line fisheries. Our study shows that contrast against the background, rather than colour per se, may be more important for object detection by sharks. This may help us to design long-line fishing lures that are less attractive to sharks as well as to design swimming attire and surf craft that have a lower visual contrast to sharks and, therefore, are less 'attractive' to them," said Prof. Hart.

Sharks are efficient predators and their evolutionary success is thought to be due in part to an impressive range of sensory systems, including vision. To date, it is unclear whether sharks have color vision, despite well-developed eyes and a large sensory brain area dedicated to the processing of visual information. In an attempt to demonstrate whether or not sharks have color vision, Hart and colleagues used a different technique - microspectrophotometry - to identify cone visual pigments in shark retinas and measure their spectral absorbance.

They looked at the retinas of 17 shark species caught in a variety of waters in both Queensland and Western Australia. Rod cells were the most common type of photoreceptor in all species. In ten of the 17 species, no cone cells were observed. However, cones were found in the retinae of 7 species of shark from three different families and in each case only a single type of long-wavelength-sensitive cone photoreceptor was present. Hart and team's results provide strong evidence that sharks possess only a single cone type, suggesting that sharks may be cone monochromats, and therefore potentially totally color blind.

The authors conclude : "While cone monochromacy on land is rare, it may be a common strategy in the marine environment. Many aquatic mammals − whales, dolphins and seals − also possess only a single, green-sensitive cone type. It appears that both sharks and marine mammals may have arrived at the same visual design by convergent evolution, in other words, they acquired the same biological trait in unrelated lineages."

Source : Springer


--
Thanks&Regards
Mahantesh.I.B
www.biotrack.yolasite.com
www.sitbiotech.blogspot.com
+91 9611558989
+91 9037652343



New TB vaccine enters proof-of-concept trial in people living with HIV

Aeras and the Oxford-Emergent Tuberculosis Consortium (OETC) announce today the start of a Phase IIb proof-of-concept efficacy trial of a new investigational tuberculosis (TB) vaccine that involves people living with the human immunodeficiency virus (HIV). The trial will be conducted at research sites in Senegal and South Africa with primary funding support from the European and Developing Countries Clinical Trials Partnership (EDCTP). TB is a leading cause of death for people infected with HIV and the second leading infectious disease killer in the world. This is the first proof-of-concept efficacy trial in people infected with HIV using MVA85A, which is being developed by OETC (a joint venture between the University of Oxford and Emergent BioSolutions) and Aeras. It is expected that the trial will generate important safety, immunogenicity and efficacy data about this vaccine.

The trial will test the vaccine candidate in approximately 1,400 adults ages 18-50 who are infected with HIV. The study will be led by the UK Medical Research Council in The Gambia, Aeras, and the University of Oxford, and conducted at two sites by the University of Cape Town (UCT) Institute of Infectious Disease and Molecular Medicine in Khayelitsha, South Africa and Laboratoire de Bacteriologie-Virologie du Centre Hospitalier Universitaire Aristide Le Dantec in Dakar, Senegal. This follows the first proof-of-concept clinical trial of the same candidate TB vaccine, which recently reached full enrollment with almost 3,000 infant participants in South Africa. "Clinical trials of new vaccines against tuberculosis must be an urgent priority on our agenda, as too many lives are lost to TB, especially among people living with HIV," said Member of the European Parliament Michael Cashman. "I recently visited a clinical trial site of this vaccine candidate in infants in South Africa, and I was impressed with the progress. I am anxious to see a new TB vaccine licensed, and I am proud that European Union Member States are investing in this critically-important work."

Professor Charles Mgone, Executive Director of EDCTP, said, "The TB and HIV co-epidemic is devastating, requiring a concerted global response. EDCTP in partnership with Aeras, Oxford-Emergent Tuberculosis Consortium and others is committed to accelerate research and development of this promising vaccine against tuberculosis by co-financing the clinical trial as an essential part in its evaluation."

Tuberculosis kills 1.7 million people per year, and more than two billion people worldwide are infected with TB – approximately one out of every three people on the planet. People infected with HIV living in countries with high TB prevalence are 20 times more likely to develop TB than those who are HIV-negative. In 2008, there were an estimated 1.4 million new cases of TB among persons with HIV infection, and TB accounted for 23 percent of AIDS-related deaths, according to the World Health Organization (WHO). The Bacille Calmette-Guérin (BCG) vaccine, the only currently-licensed vaccine against TB, is not effective in preventing adult pulmonary TB, the most common form of the disease. "A new, more effective TB vaccine would be game-changing in international efforts to eliminate TB globally by 2050," said Jim Connolly, President and Chief Executive Officer of Aeras. "Studies have already shown that this promising vaccine has an acceptable safety profile and stimulates strong immune responses in HIV-infected individuals."

Aeras is the trial sponsor, and significant funding is provided by EDCTP, a pan-European body that supports multicenter projects which combine clinical trials, capacity building and networking. This study has been approved by the Medicines Control Council of South Africa, the South African Department of Health, and the Comité National d'Ethique pour la Recherche en Santé (CNERS) in Senegal. The Scientific Institute of Public Health (WIV-ISP) in Belgium, which first identified the antigen 85A for possible use in a vaccine candidate, is providing in-kind laboratory services for the study. "Together with our partners, Emergent BioSolutions is proud to be leading the development of a new vaccine to defeat TB, one of the world's deadliest infectious diseases. This trial is particularly critical because of its focus on adults living with HIV. If we are successful, MVA85A will help make the dream of a world free from TB a reality," said Fuad El-Hibri, Chairman and Chief Executive Officer of Emergent BioSolutions. 

"It is great to see the vaccine candidate we initially developed at Oxford University reach this stage of clinical trials," said Dr. Helen McShane, a Wellcome Trust Senior Clinical Research Fellow at the University of Oxford. "In the next few years we should begin to get results on how effective the vaccine is in protecting those who are most at risk of TB. It's our hope that this vaccine will turn out to be a powerful new weapon to combat TB in the parts of the world that need it most."


--
Thanks&Regards
Mahantesh.I.B
www.biotrack.yolasite.com
www.sitbiotech.blogspot.com
+91 9611558989
+91 9037652343



Like humans, amoebae pack a lunch before they travel

Some amoebae do what many people do. Before they travel, they pack a lunch.

In results of a study reported today in the journal Nature, evolutionary biologists Joan Strassmann and David Queller of Rice University show that long-studied social amoebae Dictyostellum discoideum (commonly known as slime molds) increase their odds of survival through a rudimentary form of agriculture. Research by lead author Debra Brock, a graduate student at Rice, found that some amoebae sequester their food--particular strains of bacteria--for later use.

"We now know that primitively social slime molds have genetic variation in their ability to farm beneficial bacteria as a food source," says George Gilchrist, program director in the National Science Foundation's Division of Environmental Biology, which funded the research. "But the catch is that with the benefits of a portable food source, comes the cost of harboring harmful bacteria." After these "farmer" amoebae aggregate into a slug, they migrate in search of nourishment--and form a fruiting body, or a stalk of dead amoebae topped by a sorus, a structure containing fertile spores. Then they release the bacteria-containing spores to the environment as feedstock for continued growth.

The findings run counter to the presumption that all "Dicty" eat everything in sight before they enter the social spore-forming stage. Non-farmer amoebae do eat everything, but farmers were found to leave food uneaten, and their slugs don't travel as far. Perhaps because they don't have to. The advantages of going hungry now to ensure a good food supply later are clear, as farmers are able to thrive in environments in which non-farmers find little food. The researchers found that about a third of wild-collected Dicty are farmers. Instead of consuming all the bacteria they encounter, these amoebae eat less and incorporate bacteria into their migratory systems.

Brock showed that carrying bacteria is a genetic trait by eliminating all living bacteria from four farmers and four non-farmers--the control group--by treating them with antibiotics. All amoebae were grown on dead bacteria; tests confirmed that they were free of live bacteria. When the eight clones were then fed live bacteria, the farmers all regained their abilities to seed bacteria colonies, while the non-farmers did not. Dicty farmers are always farmers; non-farmers never learn.

Rice graduate student Tracy Douglas co-authored the paper with Brock, Queller and Strassmann. She confirmed that farmers and non-farmers belong to the same species and do not form a distinct evolved group. Still, mysteries remain.

The researchers want to know what genetic differences separate farmers from non-farmers. They also wonder why farmer clones don't migrate as far as their counterparts.

It might be a consequence of bacterial interference, they say, or an evolved response, since farmers carry the seeds of their own food supply and don't need to go as far. Also, some seemingly useless or even harmful bacteria are not consumed as food, but may serve an as-yet-undetermined function, Brock says.

That has implications for treating disease as it may, for instance, provide clues to the way tuberculosis bacteria invade cells, says Strassmann, infecting the host while resisting attempts to break them down. The results demonstrate the importance of working in natural environments with wild organisms whose complex ties to their living environment have not been broken.

Source : National Science Foundation


--
Thanks&Regards
Mahantesh.I.B
www.biotrack.yolasite.com
www.sitbiotech.blogspot.com
+91 9611558989
+91 9037652343



Your genome in minutes: New technology could slash sequencing time

Scientists from Imperial College London are developing technology that could ultimately sequence a person's genome in mere minutes, at a fraction of the cost of current commercial techniques.

The researchers have patented an early prototype technology that they believe could lead to an ultrafast commercial DNA sequencing tool within ten years. Their work is described in a study published this month in the journal 'Nano Letters' and it is supported by the Wellcome Trust Translational Award and the Corrigan Foundation.

The research suggests that scientists could eventually sequence an entire genome in a single lab procedure, whereas at present it can only be sequenced after being broken into pieces in a highly complex and time-consuming process. Fast and inexpensive genome sequencing could allow ordinary people to unlock the secrets of their own DNA, revealing their personal susceptibility to diseases such as Alzheimer's, diabetes and cancer. Medical professionals are already using genome sequencing to understand population-wide health issues and research ways to tailor individualised treatments or preventions.

Dr Joshua Edel, one of the authors on the study from the Department of Chemistry at Imperial College London, said: "Compared with current technology, this device could lead to much cheaper sequencing: just a few dollars, compared with $1m to sequence an entire genome in 2007. We haven't tried it on a whole genome yet but our initial experiments suggest that you could theoretically do a complete scan of the 3,165 million bases in the human genome within minutes, providing huge benefits for medical tests, or DNA profiles for police and security work. It should be significantly faster and more reliable, and would be easy to scale up to create a device with the capacity to read up to 10 million bases per second, versus the typical 10 bases per second you get with the present day single molecule real-time techniques."


--
Thanks&Regards
Mahantesh.I.B
www.biotrack.yolasite.com
www.sitbiotech.blogspot.com
+91 9611558989
+91 9037652343



Learning the language of bacteria

Bacteria are among the simplest organisms in nature, but many of them can still talk to each other, using a chemical "language" that is critical to the process of infection. Sending and receiving chemical signals allows bacteria to mind their own business when they are scarce and vulnerable, and then mount an attack after they become numerous enough to overwhelm the host's immune system.

This system, called "quorum sensing," is an interesting example of sophistication among microbes, says Helen Blackwell, an associate professor of chemistry at the University of Wisconsin-Madison. In practical terms, she adds, quorum sensing may provide an alternative therapeutic target as bacteria continue to evolve resistance to antibiotics.

Theoretically, blocking quorum sensing would prevent the bacteria from turning pathogenic and producing the toxins that are an immediate cause of disease in bacterial infections.

Bacteria use simple chemical signals to control quorum sensing, and Blackwell is interested in how these compounds work and in developing new ways to intercept them. In a study just published online in the journal ChemBioChem, Blackwell and colleagues Andrew Palmer, Evan Streng and Kelsea Jewell showed that several species of bacteria can respond to identical signals, suggesting that one drug could battle quorum sensing in several types of bacteria. Many bacteria use a class of molecules called lactones for quorum sensing, and Blackwell's lab has synthesized many non-native lactones, and then tested them in two species of bacteria that use identical native lactone signals. Overall, the organisms responded similarly to the same synthetic molecules, despite the dramatic differences between the species. These results suggest that the same basic chemical sensing mechanism could be common among microbes, Blackwell says. "That tells us that we can use these classes of chemicals to study — and perhaps eventually fight — a much broader range of bacteria."

Finding a broad-spectrum activity for the synthetic lactones is good news, Blackwell adds. "Bacteria come in countless varieties, and the ability to target multiple organisms with one compound could streamline the search for drugs. At the same time, we also have found differences in signal selectivity that may allow us to target some bacteria while ignoring others." That could provide the best of both worlds, Blackwell says. One drug might halt multiple infections, but related drugs might affect only one microbe in a mixture. "The data indicate that it should be possible to design and use compounds that are either selective or broad-spectrum."


--
Thanks&Regards
Mahantesh.I.B
www.biotrack.yolasite.com
www.sitbiotech.blogspot.com
+91 9611558989
+91 9037652343