GOLLYGEE!

Theme by Anders Norén

Category: Genetics (page 8 of 8)

10.06.2012

stem cells yield eggs

Mouse stem cells yield viable eggs that produce fertile offspring

This week brought big news on the stem cell front. A research group in Japan, under the leadership of  Mitntori Saitou, has produced viable eggs from mouse stem cells, producing a healthy set of baby mice. Stem cells have produced eggs and sperm before, but this is the first report of viable cells yielding fertile offspring. The breakthrough is in the October 4 issue of Science magazine. A summary from Science News:

In the new study, Saitou and colleagues started with stem cells from very early mouse embryos as well as stem cells reprogrammed from fetal cells, known as induced pluripotent stem cells. Saitou’s team manipulated the activity of a few genes in the stem cells to turn them into cells that resemble precursors of gametes, as eggs and sperm are sometimes known.

These primordial germ cell–like cells, as they are called, were mixed with support cells from an embryonic ovary and then transplanted into adult mice. Once the precursor cells had developed into oocytes, the researchers pulled them out and fertilized them in the lab before implanting the resulting embryos in female mice.

The oocytes made from either type of stem cell produced mouse pups 3.9 percent of the time. That rate is lower than for primordial germ cells taken directly from mouse embryos, which the researchers found produced pups 17.3 percent of the time. Oocytes taken from the ovaries of 3-week-old mice generated offspring 12.7 percent of the time. Female pups resulting from stem cell–derived eggs grew up to become fertile adults, the researchers report.

About half of the stem–cell derived oocytes had an extra set of chromosomes, the researchers discovered. That indicates a breakdown in meiosis, the process of halving the genetic material doled out to eggs and sperm. Saitou acknowledges there is room for improvement in his group’s technique.

09.28.2012

sars-like virus has bat origins

Genomic sequencing  of a SARS-like virus suggests retlation to a virus that is known to infect bats. From NPR news:

Dutch virologists have just published the whole genome of the new coronavirus — all 30,118 letters of its code. And, the sequence reveals that the mystery virus is most closely related to coronaviruses that infect bats in Southeast Asia.

In fact, the pathogen is more similar to two bat viruses than it is to the human SARS virus that sent the world into a panic when it infected nearly 8,000 people in 2003.

Virologist Ron Fouchier, who has done controversial work on bird flu viruses, led the sequencing effort of the SARS-like virus. He tells Shots the results suggest that the new coronavirus virus came from bats. “Bats harbor many coronaviruses, so it’s logical to assume that bats are the natural reservoir” of the new pathogen, he says.

“But this doesn’t mean the Saudi man contracted the virus from bats,” says Fouchier.

When viruses jump from animals to humans, there’s usually a second animal that connects the natural carrier with humans. This species is called the amplifier because it increases the number of viral particles that can hop over into people.

09.15.2012

patented genes

I’m late with this update, but last month BRCA genes, which are linked to increased risk for breast and ovarian cancers, were ruled patentable for the second time. The decision will likely be appealed. From Science:

In today’s opinion, CAFC rules that Myriad’s patents on the genes themselves are valid “because each of the claimed molecules represents a nonnaturally occurring composition of matter.” This reasoning assumes that the patents are based on “nonnatural” segments of DNA extracted from cells, not DNA as it occurs in the nucleus. The court also rules that a method of screening for potential cancer therapeutics by tracking their effects on cell growth rates is patentable, contrary to the view of a lower court. But CAFC finds invalid the company’s claims on testing for cancer risk by comparing or analyzing DNA sequences because these methods are based on “abstract, mental steps” of logic that are not “transformative.”

One of the three deciding judges, William Bryson, dissents in part from the majority opinion, arguing that Myriad’s claims to the BRCA gene and gene fragments are not valid. He writes that he feared that if the majority opinion stands, it “will likely have broad consequences, such as preempting methods for whole-genome sequencing.”

The decision is not likely to fully satisfy either of the battling parties, although some biotech companies may be relieved to learn that the court did not wipe out any gene patents.

Myriad has not responded to an e-mail query about what it planned to do next. Attorney Daniel Ravicher of PUBPAT, who has led the legal battle against the BRCA patents, responds that his group has not “made any final decisions about what we’ll do. … But we are not satisfied with this result, and think the dissenting judge in the Court of Appeals decision today is correct that isolated human genes are not patentable.”

Newer posts »
//weshooship.net/4/4535925