Scientists at the Instituto Gulbenkian de Ciência (IGC), in Portugal, are to date the only research group in the world capable of isolating the sperm cells in the pollen grain of the model plant Arabidopsis thaliana.
This technique was crucial in a study to be published in the latest issue of the journal Cell, which describes how mobile sequences of DNA (called transposable elements) are silenced in the sperm cells, thus ensuring suppression of the mutagenic effects of these DNA elements.
Jörg Becker, José Feijó and their team, at the IGC, and Robert Martienssen and colleagues, at the Cold Spring Harbor Laboratory, CSHL,in the USA, have unveiled a mechanism for controlling transposable elements that appears to be extensible to other eukaryotes, such as the fruit fly, amoebae and algae.
Transposable elements are very common in all known genomes. In the human genome, for example, they make up 45% of the total genome. They are involved in the evolution of genomes, since when integrated back into the genome they can affect the function and organisation of other genes. However, transposable elements are mutagens, and, therefore, their activation needs to be under tight control, as it may be harmful to the cell and the organism. If such harmful mutations occur in sexual cells, they will be transmitted to the progeny and spread in the population.
Keith Slotkin of the Martienssen lab made the surprising observation that, unlike other cells in the adult plant, transposable elements are highly active in the pollen grain of Arabidopsis thaliana. Pollen grains contain two sperm cells (the sexual cells) and an accompanying vegetative nucleus, whose DNA is not passed on to the next generation. Thanks to the technique developed by Jörg Becker's team, the researchers were able to pinpoint the location of the transposable elements' activity to the vegetative nucleus.
The researchers wanted to understand why the transposable elements weren't activated in the sperm cells. Using the sperm cell sorting technique developed at the IGC, they found that small interfering RNA's (siRNAs) accumulate in the neighbouring sperm cells, where they supposedly target the transposable elements and lead to their silencing, thus preventing the deleterious effects that their activation could have in ensuing plant development.
Says Jörg Becker, 'Overcoming the hurdles in optimising the technique was only possible because at the IGC groups researching pollen development work side-by-side with others developing cell-sorter techniques for lymphocytes. We are now able to look at the activation pattern of genes in sperm cells and are gathering surprising findings that these cells are genetically more active than previously thought. This pattern is now gradually being dissected to try to unravel the role of the genes activated in sperm cell in development of the sperm cells themselves and potentially even in the development of the embryo after fertilization.
This study suggests that also in other eukaryotic organisms which have companion cells to the sexual cells, this mechanism of silencing of transposable elements via siRNA synthesis in adjacent nuclei to the ones that carry hereditary genetic information may be acting.
Ana Godinho | EurekAlert!
First time-lapse footage of cell activity during limb regeneration
25.10.2016 | eLife
Phenotype at the push of a button
25.10.2016 | Institut für Pflanzenbiochemie
Ultrafast lasers have introduced new possibilities in engraving ultrafine structures, and scientists are now also investigating how to use them to etch microstructures into thin glass. There are possible applications in analytics (lab on a chip) and especially in electronics and the consumer sector, where great interest has been shown.
This new method was born of a surprising phenomenon: irradiating glass in a particular way with an ultrafast laser has the effect of making the glass up to a...
Terahertz excitation of selected crystal vibrations leads to an effective magnetic field that drives coherent spin motion
Controlling functional properties by light is one of the grand goals in modern condensed matter physics and materials science. A new study now demonstrates how...
Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.
"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...
In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.
A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...
By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.
"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...
14.10.2016 | Event News
14.10.2016 | Event News
12.10.2016 | Event News
25.10.2016 | Earth Sciences
25.10.2016 | Power and Electrical Engineering
25.10.2016 | Process Engineering