[ppi] [ppiindia] Hukum Mendel ada kemungkinan keliru

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Mendel's Law May Be Flawed 
Associated Press

Story location:
http://www.wired.com/news/technology/0,1282,66995,00.html

11:22 AM Mar. 23, 2005 PT

Challenging a scientific law of inheritance that has
stood for 150 years, scientists say plants sometimes
select better bits of DNA in order to develop normally
even when their predecessors carried genetic flaws.

The conclusion by Purdue University molecular
biologists contradicts at least some basic rules of
plant evolution that were believed to be absolute
since the mid-1800s, when Austrian monk Gregor Mendel
experimented with peas and saw that traits are passed
on from one generation to the next. Mendelian genetics
has been the foundation of both crop hybridization and
the understanding of basic cell mutations and trait
inheritance.

In the Purdue experiment, researchers found that a
watercress plant sometimes corrects the genetic code
it inherited from its flawed parents and grows
normally like its grandparents and other ancestors.

Scientists said the discovery raises questions of
whether humans also have the potential for avoiding
genetic flaws or even repairing them, although they
said the actual proteins responsible for making these
fixes probably would be different in plants.

Details of the experiments appear in Thursday's issue
of the journal Nature.

"This means that inheritance can happen more flexibly
than we thought," said Robert Pruitt, the paper's
senior author.

In the experiment, the Purdue researchers found that
10 percent of watercress plants with two copies of a
mutant gene called "hothead" didn't always blossom
with deformed flowers like their parents, which
carried the mutant genes. Instead, those plants had
normal white flowers like their grandparents, which
didn't carry the hothead gene and the deformity
appeared only for a single generation.

The normal watercress plants with hothead genes appear
to have kept a copy of the genetic coding from the
grandparent plants and used it as a template to grow
normally.

However, Pruitt's team didn't find the template in the
plants' DNA or chromosomes where genetic information
is stored and they did not determine whether a
particular gene is encoded to carry out the recovery
of the normal DNA.

Where the normal genetic template is stored and how it
is triggered will take additional research and
probably involve more genes, Pruitt said.

Humans and other animals do not carry the hothead
gene, so if this process occurs in higher organisms it
must use a different trigger, he said.

Other scientists described the results as
"spectacular."

Detlef Weigel and Gerds Jurgen of the Max Planck
Institute for Developmental Biology in Germany wrote
in an accompanying commentary in Nature that the
mechanism for recovering the normal DNA in the
watercress plants might be lurking in the plant's RNA,
which carries out genetic orders in cells.

End of story




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