Genetics

The DNA in our cells is constantly under assault from oxygen, the sun's radiation and environmental stresses. Most of the time, our cells can repair the damage before it gets copied into a permanent mutation that could lead to cancer. Adding a wrinkle to our understanding of how cancers begin, scientists have found that cells can turn on tumor-promoting growth circuits as a result of misreading damaged DNA without copying it: a process called "transcriptional mutagenesis.

Aging - we are all doing it. It is relentless and terminal. Auguries and alchemists, mendicants and magicians, philosophers and science fiction writers, researchers and plastic surgeons have employed all their various arts in the pursuits of "turning back the clock." Yet, we stand in modern times with a span of a century to our name, at most.

Scientists have new insight into the response of human skin to radiation and what drives the most aggressive and deadly form of skin cancer. The research, published by Cell Press in the November 21st issue of the journal Molecular Cell, may be useful in the design of new strategies for prevention of malignant melanoma. The process of tanning involves synthesis of the pigment melanin by skin cells known as melanocytes.

We analyse endangered Asian elephants (Elephas maximus) across their range to explain the unusual coexistence of ancient maternal genetic lineages. Such coexistence could result from hybridization between ancestral species, or population isolation and subsequent contact naturally or through trade. Estimating ages of lineages, inferring areas of origin, and examining fossil records, we find that both lineages probably originated in the ancestral species Elephas hysudricus, 1.6-2.

One of the most reliable indicators to predict that a person will develop type 2 diabetes is the presence of insulin resistance. Insulin is produced in the pancreas and is the hormone responsible for ensuring that glucose reaches several tissues and organs in the body, such as muscles. Insulin resistance is characterized by the lack of tissue response to insulin and is counteracted by a greater production of insulin by the pancreas.

Olivier Delattre's team (Inserm Unit 830 "Genetics and Biology of Cancer") of the Institut Curie reveal in an article in the 16 October issue of Nature that alteration of the ALK gene is closely associated with the most frequent solid extracerebral tumor in children neuroblastoma. By studying the familial forms of this tumor, the researchers also conclude that ALK is a gene that predisposes to neuroblastoma. This discovery may allow the development of new treatments in neuroblastomas.

Background: Alteration in epigenetic methylation can affect gene expression and other processes. In Prokaryota, DNA methyltransferase genes frequently move between genomes and present a potential threat. A methyl-specific deoxyribonuclease, McrBC, of Escherichia coli cuts invading methylated DNAs. Here we examined whether McrBC competes with genome methylation systems through host killing by chromosome cleavage. Results: McrBC inhibited the establishment of a plasmid carrying a PvuII methyltransferase gene but lacking its recognition sites, likely through the lethal cleavage of chromosomes that become methylated. Indeed, its phage-mediated transfer caused McrBC-dependent chromosome cleavage. Its induction led to cell death accompanied by chromosome methylation, cleavage and degradation. RecA/RecBCD functions affect the chromosome processing and, together with SOS response, reduce the lethality. Our evolutionary/genomic analyses of mcrBC homologs revealed (i) wide distribution in Prokaryota, (ii) frequent distant horizontal transfer and linkage with mobility-related genes, (iii) diversification in the DNA binding domain. In these features, McrBCs resemble Type II restriction-modification systems, which behave as selfish mobile elements maintaining their frequency by host killing. McrBCs are frequently found linked with a methyltransferase homolog, which suggests a functional association. Conclusions: Our experiments indicate McrBC can respond to genome methylation systems by host killing. Combined with our evolutionary/genomic analyses, they support our hypothesis McrBCs have evolved as mobile elements competing with specific genome methylation systems through host killing. To our knowledge, this represents the first report of a defense system against epigenetic systems through cell death.

Women with a strong family history of breast cancer have a four times greater risk for the disease than women in the general population, even if they do not carry a mutation of the BRCA gene, according to a study presented Monday at the American Association for Cancer Research's annual

Invitrogen Corporation (NASDAQ:IVGN), a provider of essential life science technologies for research, production and diagnostics, today announced the introduction of its Invivofectamine™ delivery reagent which enables short interference ribonucleic acid (siRNA) experiments in vivo. The study of RNA interference (RNAi) has revolutionized biology by allowing researchers to directly observe the effects of the loss of function of specific genes in mammalian systems.

TaconicArtemis GmbH, a subsidiary of Taconic today announced the publication of a scientific breakthrough achieved in a collaboration with the Universities Goettingen and Wuerzburg (Germany). For the first time it is now possible to inactivate disease-related genes in an inducible and reversible fashion in transgenic rats as rodent model organisms.

BRISBANE'S National Centre for Adult Stem Cell Research will commence a pilot study into a devastating genetic disease in which active young people progressively develop paraplegia. The little-known disease, Hereditary Spastic Paraplegia, has about 1000 diagnosed sufferers in Australia, but the mutations responsible may lurk in the genes of an unknown percentage of the population.

Genetic science's potential to save lives may be compromised by anachronistic patent laws, according to a leading genetic cancer specialist and a patents lawyer who will make their case at a groundbreaking debate in Sydney today (20/11).

Scientists at the Buck Institute for Age Research have identified for the first time biomarkers of aging which are highly predictive of both chronological and physiological age. Biomarkers are biochemical features that can be used to measure the progress of disease or the effects of treatment. The research involves nematode worms, microarrays which measure changes in gene expression, and complex computer algorithms.

The UK National Stem Cell Network (UKNSCN) has announced that Professor Janet Rossant, one of the world's foremost developmental biologists from The Hospital for Sick Children in Toronto, will deliver the second annual Dame Anne McLaren Memorial Lecture. The Lecture is the principal keynote address of the UKNSCN's annual research conference, being next year in Oxford, 6-8 April.

Biotech scientists increasingly are applying genomics technologies to toxicology research to better understand the effects of novel drug candidates on a variety of organ systems, reports Genetic Engineering & Biotechnology News (GEN). They are especially interested in figuring out a new compound's mechanism of action and eventually developing a predictive toxicology technique, according to the November 15 issue of GEN.

In contrast to recent findings, two of the most common medications used to treat attention deficit hyperactivity disorder (ADHD) do not appear to cause genetic damage in children who take them as prescribed, according to a new study by researchers at the National Institutes of Health (NIH) and Duke University Medical Center.

Genetic testing for type 2 diabetes is still in its infancy, said researchers who did a US study that compared risk assessment based on screening for gene variants with more traditional risk factors like weight, blood pressure and blood sugar.

Research paper publishing today in the Journal of Pathology. The generation of new mouse models of human disease is accelerating rapidly due to the completion of whole-genome sequencing efforts and technological advances in the manipulation of the mouse genome.

Over the years, hunting for cancer-related genes and understanding how they work has been an important, although time-consuming, exercise. At Cold Spring Harbor Laboratory (CSHL), five different research groups have now combined their expertise to speed up the rate of discovering cancer-related genes and validating their function in living animals.

Researchers from Lombardi Comprehensive Cancer Center/Georgetown University Medical Center are presenting numerous scientific findings at the Seventh Annual AACR International Conference on Frontiers in Cancer Prevention Research in Washington, Nov. 16-19, 2008.