HOUSTON, July 8 (UPI) -- The U.S. space agency says it's selected target launch dates for the remaining eight space shuttle missions for 2009 and 2010.

The National Aeronautics and Space Administration missions include one flight to the Hubble Space Telescope, seven assembly flights to the International Space Station and two station contingency flights, planned to be completed before the end of fiscal year 2010.

The agency previously selected Oct. 8 and Nov. 10 as launch dates for Atlantis' STS-125 mission to service Hubble and Endeavour's STS-126 mission to supply the space station and service truss supports that hold equipment and solar arrays.

NASA said the target dates -- subject to change -- reflect its commitment to complete assembly of the station and to retire the shuttle fleet as transition continues to the new launch vehicles, including Ares and Orion.

The final space shuttle mission is to be launched May 31, 2010.

The updated shuttle launch manifest is available at http://www.nasa.gov/mission_pages/station/structure/iss_manifest.html.

Mouse embryonic stem cells build a heart

ST. LOUIS, July 8 (UPI) -- U.S. researchers have shown mouse embryonic stem cells can build the heart, thereby moving science closer to heart disease treatments using human stem cells.

Washington University School of Medicine in St. Louis researchers discovered the Mesp1 gene locks mouse embryonic stem cells into becoming heart parts and moves them to the area where the heart forms. The researchers are now testing if stem cells exposed to Mesp1 can help fix damaged mouse hearts.

"This isn't the only gene we'll need to get stem cells to repair damaged hearts but it's a key piece of the puzzle," said Dr. Kenneth Murphy, a professor of pathology and immunology and senior author of the study. "This gene is like the first domino in a chain: the Mesp1 protein activates genes that make other important proteins, and these in turn activate other genes and so on. The end result of these falling genetic dominoes is your whole cardiovascular system."

The study is reported in the journal Cell Stem Cell.

New use possible for ethanol plant wastes

WASHINGTON, July 8 (UPI) -- U.S. scientists say a byproduct of corn ethanol fuel production might become useful as a way of controlling weeds in potted ornamental plants.

Researchers said the potential herbicide -- dried distillers grains with solubles, or DDGS -- is a byproduct of converting corn to fuel ethanol.

DDGS is typically used as livestock feed but U.S. Department of Agriculture researchers Rick Boydston, Harold Collins and Steve Vaughn undertook a study to evaluate the use of DDGS as a weed deterrent on potted ornamentals.

They applied DDGS two ways: to the soil surface and mixed into the potting media of transplanted ornamentals.

Applied to the soil surface after transplanting, the researchers found DDGS caused no injury to plants and reduced the amount of common chickweed and annual bluegrass. Weed control was not perfect, Boydston said, but could reduce hand-weeding.

When mixed into the potting media, however, DDDS was toxic to transplanted rose, coreopsis and phlox plants.

The scientists noted additional research is needed to identify and confirm the safety of using DDGS on other ornamentals and its effectiveness of controlling other types of weeds.

The study results appeared in the February issue of HortScience.

Microchip to aid lung cancer treatments

BOSTON, July 8 (UPI) -- U.S. medical scientists say they've found circulating tumor cells reveal genetic signatures of dangerous lung cancers, possibly leading to targeted therapy.

Massachusetts General Hospital investigators say a microchip-based device they developed -- called the CTC chip -- can detect and analyze tumor cells in the bloodstream to determine the genetic signature of lung tumors.

"When the device is ready for larger clinical trials, it should give us new options for measuring treatment response, defining prognostic and predictive measures and studying the biology of blood-borne metastasis, which is the primary method by which cancer spreads and becomes lethal," said Dr. Daniel Haber, the study's senior author.

CTCs -- circulating tumor cells -- are living solid-tumor cells found at extremely low levels in the bloodstream. Until the development of the chip it wasn't possible to get information from CTCs that would be useful for clinical decision-making.

The current study was designed to determine whether the device could go beyond detecting CTCs to helping analyze the genetic mutations that can make a tumor sensitive to treatment with targeted therapy drugs.

A pilot study of the device is to appear in the July 24 issue of the New England Journal of Medicine.