MIT researchers unravel bacteria communication pathways
MIT researchers have figured out how bacteria ensure that they respond correctly to hundreds of incoming signals from their environment.
The researchers also successfully rewired the cellular communications pathways that control those responses, raising the possibility of engineering bacteria that can serve as biosensors to detect chemical pollutants. The work is reported in the June 13 issue of Cell.
Led by MIT biology professor Michael Laub, the team studied genomes of nearly 200 bacteria, which can have hundreds of different pathways that respond to different types of external stimuli. Nutrients, antibiotics, temperature or light can evoke a variety of responses, including transcription of particular genes.
In most cases, the pathways involve two proteins. The first protein, an enzyme known as a histidine kinase, receives the external signal and then activates the second protein, known as a response regulator.
It’s critical that each histidine kinase activate only the appropriate response regulator. Different histidine kinases are often very structurally similar, as are the response regulator proteins, so scientists have wondered how cells prevent signals from getting crossed.
“If an organism has tons of this class of signaling pathway, why do we not get a lot of crosstalk?” said Laub. “How does the kinase pick out the right target?”
Based on earlier studies, the MIT researchers theorized that the specificity of the interaction is determined by a subset of amino acids on the histidine kinase and a corresponding subset of amino acids on the response regulator.
To confirm their theory, they looked for patterns of amino acid co-evolution in pairs of histidine kinases and their target response regulators.
Co-evolution occurs when a mutation in one of the two proteins is followed by a secondary mutation in the corresponding amino acid on the other protein, allowing the protein pair to maintain their interaction.
After searching a vast database of nearly 1,300 protein pairs, they identified a small set of co-evolved amino acids. They then confirmed that these amino acids govern signaling specificity by successfully rewiring five of the pathways by mutating the target amino acids.
Such manipulation could allow scientists to engineer bacteria that exhibit novel behavior such as glowing when they detect the presence of a pollutant such as toluene, said Laub.
‘Chatter Box’ computer will unravel the science of language
Psychologists at The University of Manchester have teamed up with colleagues in the School of Computer Science to develop the speech and language model using a computer system that will be up to 1,000 times more powerful than a standard PC.
Dubbed ‘Chatter Box’, the £940K, five-year study is linked to the £1 million ‘Brain Box’ project that aims to build this new breed of computer based on biological principles that will enable it to carry out highly complex functions like those performed by the human brain.
“The human brain contains about one hundred billion nerve cells or neurons that each have to make a simple decision as to whether to ‘fire’ or not,” said Professor Steve Furber, in the School of Computer Science.
“Each neuron’s decision is based on how many other connecting neurons have fired recently. When this simple computation is distributed over billions of neurons, it is capable of supporting all the highly complex behavioural characteristics exhibited by humans.
“The Brain Box computer is being built using simple microprocessors that are designed to interact like the networks of neurons in the brain allowing it to replicate sophisticated functions such as speech.”
Once the team have successfully produced the machine they will use it to build a model of normal human language capable of reading, comprehending, speaking, naming and repeating basic words in English.
“To train such a model using existing computer simulators would take far too long – possibly more than a lifetime,” said Dr Stephen Welbourne, in the School of Psychological Sciences.
“We will validate this model by showing that damaging it can lead to the same patterns of behaviour as those found in brain-damaged individuals.
“We will then use the model to predict the results of different speech therapy strategies and will test these predictions in a population of stroke patients who have linguistic problems.
“Our goal is to understand how the brain supports language function, how this breaks down after brain damage and the mechanisms that support recovery and rehabilitation.”
The Chatter Box study has been funded by the Engineering and Physical Sciences Research Council, the Medical Research Council and the Biotechnology and Biological Sciences Research Council under the Cognitive Foresight Programme.
New CDC Study Finds Gaps in Breastfeeding Support in U.S. Hospitals and Birth Centers
Many birth facilities in the United States are not providing maternity care that is fully supportive of breastfeeding, according to a study in today′s Morbidity and Mortality Weekly Reports (MMWR), a publication of the Centers for Disease Control and Prevention.
Research has shown that what happens in the hospital or birth center plays a crucial role in establishing breastfeeding and helping mothers to continue breastfeeding after leaving the birth facility.
The study, “Breastfeeding-Related Maternity Care Practices among Hospitals and Birth Centers – United States, 2007,” analyzed responses from nearly 2,700 birth facilities in all 50 states, the District of Columbia, and Puerto Rico. It asked birth facilities about their practices and policies in caring for women who choose to breastfeed their newborns. The practices were scored on a scale from 0 to 100 points.
The study found that hospitals and birth centers in many southern states scored lower in practices supportive of breastfeeding compared to other regions of the nation, with average total maternity practice scores ranging from 48 to 58. Seven southern states – Alabama, Arkansas, Kentucky, Louisiana, Mississippi, Oklahoma and West Virginia – also had the lowest percentages (less than 30 percent) of children who were breastfed for 6 months, according to the 2006 National Immunization Survey.
Read the rest here.
Newly Compiled Online Bee Checklist Allows Biologists To Link Important Information About All Bee Species
In time for National Pollinator Week, June 22 through June 28, biologists have completed an online effort to compile a world checklist of bees. They have identified nearly 19,500 bee species worldwide, about 2,000 more than previously estimated. There is a current crisis known as “colony collapse disorder,” an unexplained phenomenon that is wiping out colonies of honey bees throughout the United States. This has highlighted the need for more information about bee species and their interactions with the plants they pollinate.
“At a time when biological diversity is suspected to be declining at an alarming rate, it is important to have a solid baseline from which to measure future trends,” said Michael Ruggiero, senior scientist for the Integrated Taxonomic Information System at the National Museum of Natural History, who led the recently completed project. “This is very exciting because bees are critical for pollinating flowering plants, including most non-cereal food crops.”
“Honey bees are the most economically important pollinators and are currently in the news because of colony collapse disorder,” said John S. Ascher, a collaborator on the project from the American Museum of Natural History in New York. “Only about 500 bee species produce honey. Most species, however, do not produce honey or live in hives, yet they are crucial pollinators of crops and native plants.”
CDC Finds Some Bird Flu Strains have Acquired Properties that Might Enhance Potential to Infect Humans
The Centers for Disease Control and Prevention (CDC) recently released results of a study suggesting that some North American avian influenza A H7 virus strains have properties that might enhance their potential to infect humans as well as their potential to spread from human to human.
The study was recently published in the Proceedings of the National Academy of Sciences USA. Avian influenza A H7 viruses are fairly common in birds, but rarely infect humans. Most cases of avian influenza infection in humans have resulted from contact with infected poultry or contaminated surfaces.
“We know that influenza viruses are constantly changing and that is why it′s so important to watch them carefully. In this study, we discovered that some recently identified avian influenza A H7 viruses have some properties that could enhance their potential to infect people and possibly spread among people,” explained Dr. Jessica Belser, CDC lead author on the project.
Influenza viruses infect humans by attaching to certain sugar receptor molecules found on cells in the respiratory tract in humans. Influenza viruses can have differing degrees of ability to bind to these receptors. The greater an influenza virus′s ability to bind to these receptors, the greater the likelihood that the virus can cause illness in humans and possibly be passed from human to human. Three recent H7N2 strains and two H7N3 strains from North America were tested and found to bind to varying degrees to both avian and human receptors. One virus, an H7N2 virus strain isolated from an immune compromised man in New York in 2003, was found to have the greatest binding to the human sugar receptors. This study′s findings suggest that these North American avian influenza A H7 viruses are partially adapted to recognize sugar receptors preferred by human influenza viruses which are found in the human upper respiratory tract.
“The results of this study underscore the importance of continued influenza virus surveillance,” said Dr. Belser.
Health officials have also been closely monitoring a different avian influenza virus, H5N1, which began spreading among birds and poultry in Asia in 2003 and has spread to birds in other countries in Europe, the Near East, and Africa. Nearly 400 human cases of H5N1 have been reported world-wide though none of these have occurred in the United States or even the Northern Hemisphere. Most of these cases have occurred from direct or close contact with infected poultry or contaminated surfaces; however, a few cases of human-to-human spread of H5N1 virus have occurred.