Microbiology

A team of researchers at Harvard University have modeled in the laboratory a primitive cell, or protocell, that is capable of building, copying and containing DNA. Since there are no physical records of what the first primitive cells on Earth looked like, or how they grew and divided, the research team's protocell project offers a useful way to learn about how Earth's earliest cells may have interacted with their environment approximately 3.5 billion years ago. The protocell's fatty acid membrane allows chemical compounds, including the building blocks of DNA, to enter into the cell without…

Would you like a side of food poisoning with that salad? Salmonella can infect plant cells and successfully evade all the defense mechanisms of plants so cleaning the surfaces of raw fruits and vegetables, e.g. by washing, is not sufficient to protect against food poisoning, according to a study published today. The results of the project are based on a model plant, which also represents the ideal basis for future development work on treatment and testing systems in the area of food safety. 1.5 billion (!) cases of food poisoning are caused by Salmonella bacteria each year (World Health…

When patches of red, flaky and itchy skin on newborn mice led rapidly to their deaths, researchers at Washington University School of Medicine in St. Louis looked for the reason why. What they found was a molecular alarm system that serves as a sentinel to monitor the integrity of skin — the body's essential protective barrier. The fatal effects of raising this alarm in the lab mice suggests generally that certain kinds of impairments to the skin's structure can potentially trigger harmful effects in other areas of the body, according to the researchers. The research team found that the…

By adding an enzyme to adult stem cells 'in vitro', remarkable results can be booked 'in vivo', say scientists of the University of Twente in The Netherlands. Up to now, so-called mesenchymal stem cells could not succesfully be used to create new bone tissue, e.g. for repair. By adding PKA enzyme to the stem cells beforehand, a substantial amount of bone is grown after implanting the cells. Hitherto it has been difficult to induce adult human stem cells to produce bone, e.g. in order to repair bone tissue. Researchers at the University of Twente have shown that if the enzyme PKA is previously…

With improved resolution, tissue-specific molecular markers and precise timing, a group of scientists say they have possibly overturned a long-standing assumption about the origin of embryonic cells that give rise to connective and skeletal tissues that form the base of the skull and facial structures in back-boned creatures from fish to humans. University of Oregon biologist James A. Weston and co-authors from the Max Planck Institute of Immunology in Germany and the French National Scientific Research Centre at the Curie Institute document their potentially textbook-changing case in an…

In the contentious political debate over embryo stem (ES) cell research, both proponents and opponents begin with the premise that "embryos are destroyed for their cells," as President Bush claims and non-partisan journalists repeat frequently in stem cell news stories. It's only when partisans get beyond this premise that opinions diverge. Proponents of ES cell research argue that embryo destruction is justified based on the promise of extraordinary medical advances. In contrast, the President and his supporters describe ES cell derivation as "the taking of innocent human life," which is "…

How does a stem cell decide what specialized identity to adopt – or simply to remain a stem cell? A new study suggests that the conventional view, which assumes that cells are “instructed” to progress along prescribed signaling pathways, is too simplistic. Instead, it supports the idea that cells differentiate through the collective behavior of multiple genes in a network that ultimately leads to just a few endpoints – just as a marble on a hilltop can travel a nearly infinite number of downward paths, only to arrive in the same valley. The findings, published in the May 22 issue of Nature,…

600 million years of evolution has taken two unlikely distant cousins, turkeys and scallops, down very different physical paths from their common ancestor but a motor protein, myosin 2, remains structurally identical in both creatures. Myosin molecules generate tension in smooth muscle by adhering to form a filament, which grabs hold of a neighbouring filament, and relaxes by letting go. When the muscle is in a relaxed state, myosin molecule folds itself up into a compact structure. The discovery suggests that the tiny motor protein is much more important than previously thought – and for…

A team of scientists has provided, for the first time, a detailed map of how the building blocks of chromosomes, the cellular structures that contain genes, are organized in the fruit fly Drosophila melanogaster. The work identifies a critical stop sign for transcription, the first step in gene expression, and has implications for understanding how the AIDS virus regulates its genes. The scientists found that nucleosomes--chromosomal building blocks made up of proteins around which DNA is coiled--occur at precise locations along genes that are actively undergoing transcription. They also…

It has long been known that type 2 diabetes is linked to obesity, particularly fat inside the belly. Now, researchers at the Joslin Diabetes Center have found that fat from other areas of the body can actually reduce insulin resistance and improve insulin sensitivity. In a study published in the May issue of Cell Metabolism, a team lead by C. Ronald Kahn, M.D. found that subcutaneous fat -- fat found below the skin, usually in the hips and thighs -- is associated with reduced insulin levels and improved insulin sensitivity. “This points to a new opportunity to find substances made by…