ممكن معلومات عن الليزر وتأثيرها على الصفات الوراثية للانسان ضروووري

**bint uae** · 03-23-2009 10:33 PM

السلا م عليكم ورحمة الله وبركاته
لو سمحتوا بغيت معلومات بحث عن الليزر والتأثير على الصفات الوراثية بسرررعه

**سمادنيتي** · 04-13-2009 02:55 PM

والله تعذرني مو تخصصي اليزر ولكن اتوقع كتب الفيزياء الطبية تنفعك

**NADER** · 04-13-2009 09:37 PM

حياكم الله جميعا

اتمنى هذا الموضوع يفيدك :

Laser technology cuts down on corn and soybean breeding time

By ANDREA JOHNSON, Assistant Editor
Thursday, September 11, 2008 4:22 PM CDT

Scientists at DuPont have found ways to speed up the delivery of new hybrids and varieties using laser technologies.

The laser creates and amplifies a narrow, intense beam of coherent light that precisely slices seed.

At the labs of DuPont business Pioneer Hi-Bred, scientists wondered if the preciseness of laser technology could keep the germ alive while testing the seed.

They found that a laser could slice off a very specific piece of a corn kernel or soybean seed. Using laser technology plus precision alignment with magnets, scientists can take a slice so specific that the kernel or seed can still germinate and grow.

Previously, the germ was too easily clipped or snipped off. Processing the seed took longer, and contamination from other seed was possible.

“The lasers we are using are a step ahead, because it’s going to allow us to efficiently sample millions of seed before they are ever planted in the field,” said Pat Arthur, spokesperson for Pioneer out of Johnston, Iowa.

Laser-Assisted Seed Selection is one tool in Pioneer’s Accelerated Yield Technology (AYT) toolbox. It was adopted to meet the company’s goal of increasing their corn hybrid and soybean variety yields by 40 percent in 10 years.

Now Pioneer has several patents pending for the laser technology.

How it works

For corn - ears of corn from research plots are sent to the lab.

Ears of corn - not just kernels - are brought into the lab.

The ear is painted with ****llic paint.

“The very end cap of the kernel is painted,” said Arthur.

The ear is then ****led, and the kernels are put into a magnetized plate. The painted kernels line up perfectly over the plate that is divided to hold one kernel per cell.

Several plates are placed in a 120-watt carbon dioxide laser machine, about the size of a large copy machine and weighing about 250 pounds.

The laser comes across and scores or cuts a slice out of each individual seed. The seed drops down, and the test slice stays on the magnet.

“We can divide the laser into as many beams as we want,” said Arthur. “We can cut multiple seeds at a time.”

The seed is captured, packaged and identified in a blister pack - the same way some pills are packaged.

Then, the magnetic force is released on the small slices of seed. Captured in another collection plate, the slices are sent off to the molecular breeding lab.

With the adoption of molecular breeding, so much has changed within corn and soybean breeding programs.

Yet all of the years of physical analysis and observation play an important role in the success of the program today.

“The millions of phenotypic points of data Pioneer researchers have collected over the years have made AYT a reality,” said William S. Niebur, vice president - DuPont Crop Genetics Research and Development.

The information from 82 years of analysis is stored in a supercomputer that has decoded much of Pioneer’s germplasm.

The supercomputer helps researchers analyze the DNA or genetic identity of the seed and determine if the seed carries the specific traits wanted in Pioneer corn.

“We can go back to that specific kernel and plant it the next growing season,” Arthur said.

In soybeans, scientists may be looking for seed that has molecular markers for diseases such as frogeye leaf spot, brown stem rot, Asian soybean rust and yield.

Trying to stack all of those markers on one seed required breeders to grow out hundreds of thousands of seed in the past. The result of all that seed would be just a handful of seed with the specific characteristics the breeder wanted.

Now, almost all of the planted seed will already have the molecular markers for the desired traits.

Pioneer expects millions of corn and soybean seeds will be tested with the procedure by the end of 2009.

Laser-Assisted Seed Selection allows Pioneer to better use their resources. In the past, between 75-90 percent of the field space used for seed development had to be planted to corn and soybean seed that wasn’t likely to move forward.

With the new technology, Pioneer developers will advance only superior genetics through their research programs.

“Laser-Assisted Seed Selection transforms our research program, because it intensifies the impact of other AYT technologies such as molecular breeding,” said Niebur. “It enables the rapid selection of the best genetics for advancement before they ever leave the lab.

“Our engineers and scientists have come up with a truly unique technology that will have a significant impact on the rate we bring higher yielding products to Pioneer customers.”