In other scientific fields, the term nucleus may generally refer to the core or the central part around which other parts are grouped or gathered. For instance, in Physics, a nucleus refers to the positively-charged center of an atom that usually contains the protons and neutrons . In Chemistry, a nucleus is a fundamental arrangement of atoms that occur in compounds through substitution of atoms without a change in structure . In Astronomy, a nucleus is the center of the head of a comet or the central or brightest part of a nebula or galaxy . In Meteorology, a nucleus is a particle on which water vapor molecules accumulate in free air to form water drops or ice crystals.
"Our study is the first to demonstrate that the ER is where miRNA-mediated translation repression occurs," said lead researcher Xuemei Chen, a professor of plant cell and molecular biology and a Howard Hughes Medical Institute-Gordon and Betty Moore Foundation Investigator. "To understand how microRNAs repress target gene expression, we first need to know where microRNAs act in the cell. Until now no one knew that membranes are essential for microRNA activity. Our work shows that an integral membrane protein, AMP1, is required for the miRNA-mediated target gene repression to be successful. As AMP1 has counterparts in animals, our findings in plants could have broader implications."