Microbiology

Researchers at the University of Delaware have discovered that when the leaf of a plant is under attack by a pathogen, it can send out an S.O.S. to the roots for help, and the roots will respond by secreting an acid that brings beneficial bacteria to the rescue. The finding quashes the misperception that plants are "sitting ducks"--at the mercy of passing pathogens--and sheds new light on a sophisticated signaling system inside plants that rivals the nervous system in humans and animals. The green represents the beneficial bacterium Bacillus subtilis, which has formed a biofilm on the…

The DNA's double helix--the sub-microscopic core of our life--has been the subject of intense study and scrutiny for decades. Observations and measurements at the scale of DNA are tricky. The distance between the rungs in DNA's ladder (or base pairs), for example, was thought to be barely over 3 millionths of a millimeter, or 3.4 Å (angstroms). And this ladder has been typically assumed to be very rigid. But now a team of Stanford scientists, supported in part by the National Science Foundation, have used a novel molecular ruler to cast doubts on this picture. Using this molecular ruler, they…

Scientists from the Universities of Bath and Exeter have developed a rapid new way of checking for toxic genes in disease-causing bacteria which infect insects and humans. Their findings could in the future lead to new vaccines and anti-bacterial drugs. They studied a bacterium called Photorhabdus asymbiotica, which normally infects and kills insects, but which can also cause an unpleasant infection in humans. By testing groups of genes from the bacteria against three types of invertebrates (insects, worms and amoebae) and mammalian cells, the scientists were able to identify toxins and…

Proteins found in sperm are central to understanding male infertility and could be used to determine new diagnostic methods and fertility treatments according to a paper published by the journal Molecular and Cellular Proteomics (MCP). The article demonstrates how proteomics, a relatively new field focusing on the function of proteins in a cell, can be successfully applied to infertility, helping identify which proteins in sperm cells are dysfunctional. "Up to 50 percent of male-factor infertility cases in the clinic have no known cause, and therefore no direct treatment. In-depth study of…

A gene contained in laboratory yeast has helped an international team of researchers uncover new findings about the process by which protein molecules bind to control sequences in genes in order to initiate gene expression, says a new study. Previously thought to be inert carriers of the genetic instructions from DNA, so-called non-coding RNAs turn out to reveal a novel mechanism for creating access to DNA required by transcriptional activation proteins for successful gene expression, according to Boston College Biology Professor Charles Hoffman, a co-author of the study in Nature with…

Obesity is a health problem in western countries in part from an increase in the mass and number of white fat cells. Because white fat cells are post-mitotic, meaning that they cannot divide, scientists have hypothesized that a population of fat precursor cells must exist in the fat depot in order to produce new fat cells. But identifying these fat precursor cells has been difficult. Scientists at the Howard Hughes Medical Institute and Rockefeller University have discovered an important fat precursor cell that may in time explain how changes in the numbers of fat cells might increase and…

Bacteria are everywhere and can survive in almost anything. Finding out exactly how bacteria respond and adapt to stresses and dangers will further our understanding of the basic survival mechanisms of some of the most resilient, hardy organisms on Earth. Toward that goal, a bacteria cell's 'crisis command center' has been observed for the first time swinging into action to protect the cell from external stress and danger, according to new research out today. It's like Team America: World Police, except there are no animatronic puppets or Alec Baldwin impressions. The crisis command…

Small stretches of DNA with unknown utility harbor a big secret, say researchers at the Stanford University School of Medicine, but they don't know what it is. Those secrets are always the biggest. Individual laboratory animals appear to live happily when these genetic ciphers are deleted so why these snippets have been highly conserved throughout evolution is the real mystery. Small stretches of seemingly useless DNA harbor a big secret, say researchers at the Stanford University School of Medicine. There's one problem: We don't know what it is. Although individual laboratory animals appear…

A team of scientists has identified a gene in rice that controls the size and weight of rice grains. The gene may prove to be useful for breeding high-yield rice and, thus, may benefit the vast number of people who rely on this staple food for survival. The researchers first searched for and identified mutant strains of rice that exhibited underweight grains. "We found a particular mutant that is defective in its ability to produce normal-sized grains," said Zuhua He, a biology professor at the Chinese Academy of Sciences and the leader of the team. The group then examined the mutant and…

Who wouldn't want a map of all the known yeast metabolic pathways on the wall? Download your copy here (PDF). The catch is you have to print it out yourself. This poster offers a birds-eye glance at some of the complexity that goes on inside just a single cell. All of these pathways have to be coordinated with environmental cues, like changing sugar sources, and major cell processes like division. Most of these pathways happen in our cells too, and many of the key the enzyme players in yeast are conserved in humans as well. By figuring all of this out in yeast, we learn about the complexity…