Tag: genetics (page 1 of 5)

the problem with cancer cells

HeLa cells cancer research

HeLa cells, cancer cells originally isolated from Henerietta Lacks, are among the most widely used cell lines for scientific research

Cell lines are frequently used in cancer research studies. They are pretty easy to maintain and they grow fast. The cell lines give us insight into some of the cellular pathways involved in tumor biology. They are often used as early-stage screens for potential cancer therapeutics, even though scientists know that they do not exactly share the same biology as an actual tumor. Cancer cells grow rapidly and they generate many mutations in the process. In a few cycles, the cells that you have in culture are different genomically than the cells that you started with. But still, having some information on what cells maybe doing in a tumor is better than no information at all.

Now Derek Lowe calls attention to a new study in Nature, which points out a potential problem with these cell lines in culture. In this new paper, the researchers found that not only are cancer cells different from the tumor that they started from, but there can be many differences within a strains of any given cell line.  When they observed 27 strains of the MCF7 breast cancer line, the discovered rapid genetic diversification. They then looked at 13 additional cell lines and saw similar results. The genetic differences changed activation of gene expression, cell morphology and cell proliferation.

Derek Lowe sums up what this means for compound screening in cancer cell lines:

At least 75% of the compounds that showed strong inhibition of one MCF7 line were totally inactive against others. That’s going to confound experiments big-time, and this paper is a loud warning for people to be aware of this problem and to do something about it.

bigfoot revealed

yeti, sasquatch, bigfoot

Hair samples from the elusive yeti have been analyzed.

Science Magazine brings news of a peer-reviewed analysis of purported Sasquatch hair samples. Genetic analysis reveals that bigfoot is probably not bigfoot.

In 2012, researchers at the University of Oxford in the United Kingdom and the Museum of Zoology in Lausanne, Switzerland, put out a call for hair samples thought to be from anomalous primates. They received 57 hairs from Bigfoot enthusiasts and museums around the world, including samples from Washington, Texas, Oregon, Russia, and India—a few as old as 50 years. Some “hairs” immediately turned out not to be hairs at all, but rather plant or glass fibers; others were too worn to study.

he researchers, led by Oxford geneticist Bryan Sykes, focused on the remaining 37 samples, isolating and cleaning a 2- to 4-centimeter segment of each hair, many of which have been extensively handled by people, contaminating them with foreign DNA. To identify the evolutionary source of each sample, the team determined the sequence of a gene—found inside the mitochondria of cells—that encodes the 12S RNA, which is often used for species identification. Unlike standard DNA, mitochondrial genes are passed only from mother to offspring.

Seven of the samples didn’t yield enough DNA for identification. Of the 30 that were sequenced, all matched the exact 12S RNA sequences for known species, the team reports online today in the Proceedings of the Royal Society B. Ten hairs belonged to various bear species; four were from horses; four were from wolves or dogs; one was a perfect match to a human hair; and the others came from cows, raccoons, deer, and even a porcupine. Two samples, from India and Bhutan, matched polar bear 12S RNA—a surprising finding that Sykes is following up on to determine whether some Himalayan bears are hybrid species with polar bears.

Read the full text of the study free at Proceedings of the Royal Society B.

bacterial profiles by ethnicity

A Venn diagram showing bacterial profiles by ethnicity.

A group of researchers can determine your ethnicity by sampling bacterial from your mouth. From Popular Science:

Almost 400 different species were thriving in the mouths of 100 people from four different ethnic backgrounds: African American, Caucasian, Latino and Chinese. Only 2 percent of bacterial species identified were present in every individual studied. Another 8 percent of species were shared by 90 percent of the participants. Each ethnic group displayed a distinct pattern of bacteria, especially under the gums. “This suggests that the host genotype influences the microbial community to a greater extent than shared environment,” the study’s authors write.”‘Nature’ appears to win over ‘nurture’ in shaping this community.”

The researchers were able to develop an algorithm that could predict an individual’s ethnicity based on bacteria from under their gums with 62 percent accuracy. The algorithm was able to classify the bacterial communities of African American participants 100 percent of the time, but wasn’t as accurate for other ethnicities.

Read the original research at PLOS One

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