Discovery
sheds light on the way cells pass information between generations.
Biologists
at Cornell University in Ithaca, N.Y., have shown how tiny molecular
motors carrying target proteins help orient the spindle-like apparatus
that transfers genetic material from the nucleus of a mother cell
to the daughter.
Immunofluorescence
microscope photograph of yeast cells with mutant molecular motors,
left, and normal motor, right.
The research
explains an essential mechanism in the birth of a new cell, and
how failures of molecular motors can have dire consequences for
new cell formation.
Molecular
motors are tiny specialized structures that are fueled by cellular
energy in the form of adenosine triphosphate. They perform a variety
of tasks within cells. Mitosis is the process by which a mother
cell's nucleus divides to provide a duplicate set of genetic instructions
to the developing daughter cell, in the form of chromosomes. This
transfer of genetic material is absolutely essential for all organisms
because without genetic instructions, new cells cannot develop.
Even minor problems in mitosis can cause serious defects, such
as the development of cancerous cells. The new model for mitotic
mechanics, reported in the journal Nature,was worked out in budding
yeast cells, shown here. But the study is expected to prompt further
research into whether similar processes occur in the formation
of cells of all higher organisms, including humans.
“The
process of properly orienting the spindle with the axis of cell
division has to be incredibly accurate, otherwise cells run the
risk of not transferring their genetic material into newly formed
daughter cells,” says Anthony Bretscher, professor of molecular
biology and genetics at Cornell and one of four authors of the
report. “This is the first time anyone could draw a molecular
mechanism for spindle orientation in yeast. The big question is
does this also happen in human cells?”
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