Genetics & Molecular Biology
During pregnancy, many women experience remission of autoimmune diseases like multiple sclerosis and uveitis and scientists have described a biological mechanism they say is responsible for changes in the immune system that helps explain that remission.
The expression of an enzyme known as pyruvate kinase is reduced in immune cells in pregnant women compared to non-pregnant women, says biophysicist Howard R. Petty from the University of Michigan Kellogg Eye Center, and Roberto Romero, M.D., of the National Institutes for Health. Their study coming in the August issue of the American Journal of Reproductive Immunology also reports that expression of the enzyme is lower in pregnant women compared to those with pre-eclampsia, a condition with inflammatory components.
Regarding the recent Nature News article (Transcription: Enhancer makes non-coding RNA. Nature 465, 173-174; 2010) about the discovery of enhancer RNAs (eRNAs) and their apparent link with neuronal activity, an initial question that arises is whether these eRNAs are really a new class of small RNAs. The question stems from the striking similarities between eRNAs and microRNAs.
Researchers have come a long way from initially cracking the DNA code since the time of Watson and Crick, to now unveiling the complex layers of molecular codes that make up the cell’s molecular fingerprint.
These codes are no longer restricted to the 4 nucleotide codes of the DNA sequence, but rather a complex web of coding systems that regulate every stage of gene expression, including the epigenetic codes (transcriptional), microRNA codes (translational), as well as codes derived from alternative splicing of RNA transcripts (post-translational). While the existence of these codes are now dogma to most cell biologists, precisely how these codes dictate the identity of cells in a multicellular organism still remains elusive.
Hummingbirds require an enormous amount of energy to beat their wings fast enough to hover and maneuver. In many ways they appear to retain some of the flight patters of insects, but they have an enormous amount of mass in comparison. Many changes in cell structure must occur to allow this high metabolism rate, and most specifically in mitochondria to be able to provide such large quantities of energy.
Quite a few changes in cell morphology and physiology might be expected to help deal with these large metabolism rates. Greater oxygen and carbon dioxide diffusion rates in the lungs would speed the movement of these gasses, as well as increased cardiac output and increase in capillary density.
A new study published in Genome Research has identified intrinsic properties of DNA that influence mutation rate, shedding light on an area of biology that still needs to be investigated - the mechanisms involved in genome maintenance .
Some DNA mutations are subject to natural selection, either conferring a biological advantage that is selected for, or a negative effect that is selected against. Mutations not under selection are said to be neutral, and the rate at which neutral mutations accumulate is reflective of the true DNA mutation rate. Researchers can estimate this mutation rate by comparing neutrally evolving sequences in species that share a common ancestor.
Scientists have long wondered what is happening at the cellular and molecular level to bring about the amazing coordination that occurs when birds migrate or fish gather in schools.
A team of researchers writing in Science has found evidence that this collective behavior can arise in cells that initially may not be moving at all, but are prodded into action by an external agent such as a chemical. Their study has shown that food-deprived amoebae are prodded into their coordinated clumping by the chemical cyclic adenosine monophosphate (cAMP), effectively changing the parameters of the cell environment.
Multiple sclerosis (MS) is a devastating autoimmune disease, where the immune system attacks the white matter throughout the nervous system. While the cause for MS is currently unknown, epidemiological data so far suggests that the disease is likely triggered by both environmental and genetic factors. To pinpoint the molecular mechanism for MS, Sergio Baranzini and colleagues at UCSF conducted a recent twin study on multiple sclerosis using advanced tools such as genomic deep sequencing analysis. In their study published recently in Nature, Baranzini analyzed immune cells from identical twins where one of the twins has developed MS (Barazini et al., 2010). Much to their surprise, the study found no significant genomic differences between the twins.
Researchers from the University of Barcelona and the University of California, San Francisco have captured the first high resolution images of DNA unfolding.
The team studied a small DNA fragment consisting of 12 base pairs (the human genomes has about 3,000 million base pairs) and obtained 10 million structural snapshots of how DNA unfolds. In this process they revealed the two main ways by which the natural folded structure move to an unfolded state. The results of the research were published in Angewandte Chemie.
Scientists have developed the first cell controlled by a synthetic genome which may allow them to probe the basic machinery of life and engineer bacteria specially designed to solve environmental or energy problems.
The research team, led by Craig Venter, has already chemically synthesized a bacterial genome, and transplanted the genome of one bacterium to another. Now, the scientists have put both methods together, to create what they call a "synthetic cell," although only its genome is synthetic.
Researchers have programmed an autonomous molecular "robot" made out of DNA to start, move, turn, and stop while following a DNA track.
The development could ultimately lead to molecular systems that might one day be used for medical therapeutic devices and molecular-scale reconfigurable robots---robots made of many simple units that can reposition or even rebuild themselves to accomplish different tasks.
Results of the research have been published in Nature.
The traditional view of a robot is that it is "a machine that senses its environment, makes a decision, and then does something---it acts," said Erik Winfree, associate professor of computer science, computation and neural systems, and bioengineering at Caltech.