For most mammals, the oocyte cells begin as round, egg-like masses. And after fertilization, it begins to develop the body axis of the object from head to tail, front to back, and left to right.
A guess is made as to what determines these body-direction directions but have never been seen before. And now, scientists at the Marine Biological Laboratory (MBL) have filmed the beginning of this cellular rearrangement, whose results will help answer important biological questions.
“The most interesting and mysterious part of evolutionary biology is the origin of the body axis in animals,” said Tomomi Tani, a scientist at the Marine Biological Laboratory, at the Eugene Bell Center when conducting the research and now at Japan’s National Institute of Advanced Industrial Science and Technology.
And work by Tani and his colleague Hirokazu Ishii, published this week in the journal Molecular Biology of the Cell, shows that both parents help direct the body to their offspring. For the animal species studied in the research (sea fountains), the input from the mother determines the posterior axis of the abdomen, while the father determines the axis of the head and tail.
“Both maternal and paternal signals are required to establish the body’s plan for a developing animal fetus,” Tani said.
This research addresses fundamental questions in evolutionary biology and may also provide clues about why errors sometimes occur. Such knowledge could benefit fields as diverse as medicine and agriculture.
read more
The prevailing theory of how to adjust the body axis was that actin filaments (essential elements in the eukaryotic cytoskeleton) inside the egg, which participate in cell movement and contractions, work to rearrange the cytoplasmic substance in the egg after fertilization.
But seeing this happen is challenging because the onset of the process occurs quickly and at very small distances within living cells.
To overcome these hurdles, Tanni and Ishii used a fluorescent polarization microscope, a technique developed a few years ago in the marine biological laboratory by Tani and Shalin Mehta of the Chan Zuckerberg Biohub research center, and chief scientist of the Marine Biological Laboratory Rudolf Oldenburg, along with scientists at other institutions.
This technology enables the visualization of events that occur at distances measured in nanometers, or thousands of times smaller than the diameter of a human hair.
Tani pointed out that “the use of polarized light to consider the dynamics of molecular arrangement is a tradition for imaging a marine biological laboratory,” a tradition that began with pioneering living cell studies by the Japanese-American scientist Shinya Inoue (a biophysicist whose field of research was to visualize dynamic processes within living cells Using an optical microscope) in the 1950s.
When polarized, the light waves oscillate either partially or completely in only one direction: up / down, left / right, clockwise / counterclockwise, and so on. It is for this reason that the filter will allow polarized light to pass in one direction, but prevent it when rotating.
read more
Tani and Ishii linked fluorescent probe particles that glow when illuminated with the right light, to actin in sea jet oocytes (Ciona), a marine species that researchers often studied as a model for animal development.
Tani said the probe-actin link was very tough, allowing the microscope to detect the orientation of the actin molecules by working with polarized light.
Therefore, if actin points in one direction, researchers have discovered it. And if the actin is mixed, they can see that, too.
When Tani and Ishii looked at the unfertilized oocytes, they saw a mostly random arrangement of actin. After fertilization, the calcium ion wave passed through the egg and lined up the actin filaments and contracted along the direction that was at a right angle, or 90 ° to the future back / abdomen axis. Then move the cytoplasm. This process of body skeletal formation began right after fertilization.
Research to direct the fertilized egg is continued with further investigations. One of the long-term goals of such imaging is to discover and understand the force in a developing fetus that shapes its morphology, shape and structure.
Source: phys.org
Source link